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\n \n \n\n \n \n \n \n \n \n Wilder rangelands as a natural climate opportunity: Linking climate action to biodiversity conservation and social transformation.\n \n \n \n \n\n\n \n Simba, L. D.; te Beest, M.; Hawkins, H.; Larson, K. W.; Palmer, A. R.; Sandström, C.; Smart, K. G.; Kerley, G. I. H.; and Cromsigt, J. P. G. M.\n\n\n \n\n\n\n Ambio, 1: s13280–023–01976–4. January 2024.\n \n\n\n\n
\n\n\n\n \n \n![\"Wilder](\"//bibbase.org/img/filetypes/link.svg\"\n\t "\\"Paper\\"\n\t")
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\n\n\n@article{simba_wilder_2024,\n\ttitle = {Wilder rangelands as a natural climate opportunity: {Linking} climate action to biodiversity conservation and social transformation},\n\tvolume = {1},\n\tissn = {1654-7209},\n\tshorttitle = {Wilder rangelands as a natural climate opportunity},\n\turl = {https://doi.org/10.1007/s13280-023-01976-4},\n\tdoi = {10.1007/s13280-023-01976-4},\n\tabstract = {Rangelands face threats from climate and land-use change, including inappropriate climate change mitigation initiatives such as tree planting in grassy ecosystems. The marginalization and impoverishment of rangeland communities and their indigenous knowledge systems, and the loss of biodiversity and ecosystem services, are additional major challenges. To address these issues, we propose the wilder rangelands integrated framework, co-developed by South African and European scientists from diverse disciplines, as an opportunity to address the climate, livelihood, and biodiversity challenges in the world’s rangelands. More specifically, we present a Theory of Change to guide the design, monitoring, and evaluation of wilder rangelands. Through this, we aim to promote rangeland restoration, where local communities collaborate with regional and international actors to co-create new rangeland use models that simultaneously mitigate the impacts of climate change, restore biodiversity, and improve both ecosystem functioning and livelihoods.},\n\tlanguage = {en},\n\turldate = {2024-03-27},\n\tjournal = {Ambio},\n\tauthor = {Simba, Lavhelesani D. and te Beest, Mariska and Hawkins, Heidi-Jayne and Larson, Keith W. and Palmer, Anthony R. and Sandström, Camilla and Smart, Kathleen G. and Kerley, Graham I. H. and Cromsigt, Joris P. G. M.},\n\tmonth = jan,\n\tyear = {2024},\n\tkeywords = {Albedo, Biodiversity, Carbon sequestration, Methane, Natural disturbance, Nature-based solutions},\n\tpages = {s13280--023--01976--4},\n}\n\n\n\n\n\n Rangelands face threats from climate and land-use change, including inappropriate climate change mitigation initiatives such as tree planting in grassy ecosystems. The marginalization and impoverishment of rangeland communities and their indigenous knowledge systems, and the loss of biodiversity and ecosystem services, are additional major challenges. To address these issues, we propose the wilder rangelands integrated framework, co-developed by South African and European scientists from diverse disciplines, as an opportunity to address the climate, livelihood, and biodiversity challenges in the world’s rangelands. More specifically, we present a Theory of Change to guide the design, monitoring, and evaluation of wilder rangelands. Through this, we aim to promote rangeland restoration, where local communities collaborate with regional and international actors to co-create new rangeland use models that simultaneously mitigate the impacts of climate change, restore biodiversity, and improve both ecosystem functioning and livelihoods.\n
\n\n\n\n \n\n \n \n \n \n \n \n Frost damage measured by electrolyte leakage in subarctic bryophytes increases with climate warming.\n \n \n \n \n\n\n \n van Zuijlen, K.; Kassel, M.; Dorrepaal, E.; and Lett, S.\n\n\n \n\n\n\n Journal of Ecology, 112(2): 220–232. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.14236\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{van_zuijlen_frost_2024,\n\ttitle = {Frost damage measured by electrolyte leakage in subarctic bryophytes increases with climate warming},\n\tvolume = {112},\n\tcopyright = {© 2023 The Authors. Journal of Ecology published by John Wiley \\& Sons Ltd on behalf of British Ecological Society.},\n\tissn = {1365-2745},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.14236},\n\tdoi = {10.1111/1365-2745.14236},\n\tabstract = {Observed climate change in northern high latitudes is strongest in winter, but still relatively little is known about the effects of winter climate change on tundra ecosystems. Ongoing changes in winter climate and snow cover will change the intensity, duration and frequency of frost events. Bryophytes form a major component of northern ecosystems but their responses to winter climate changes are largely unknown. Here, we studied how changes in overall winter climate and snow regime affect frost damage in three common bryophyte taxa that differ in desiccation tolerance in a subarctic tundra ecosystem. We used a snow manipulation experiment where bryophyte cores were transplanted from just above the tree line to similar elevation (i.e. current cold climate) and lower elevation (i.e. near-future warmer climate scenario) in Abisko, Sweden. Here, we measured frost damage in shoots of Ptilidium ciliare, Hylocomium splendens and Sphagnum fuscum with the relative electrolyte leakage (REL) method, during late winter and spring in two consecutive years. We hypothesized that frost damage would be lower in a milder climate (low site) and higher under reduced snow cover and that taxa from moister habitats with assumed low desiccation tolerance would be more sensitive to lower temperature and thinner snow cover than those from drier and more exposed habitats. Contrary to our expectations, frost damage was highest at low elevation, while the effect of snow treatment differed across sites and taxa. At the high site, frost damage was reduced under snow addition in the taxon with the assumed lowest desiccation tolerance, S. fuscum. Surprisingly, frost damage increased with mean temperature in the bryophyte core of the preceding 14 days leading up to REL measurements and decreased with higher frost degree sums, that is, was highest in the milder climate at the low site. Synthesis Our results imply that climate warming in late winter and spring increases frost damage in bryophytes. Given the high abundance of bryophytes in tundra ecosystems, higher frost damage could alter the appearance and functioning of the tundra landscape, although the short and long-term effects on bryophyte fitness remain to be studied.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {van Zuijlen, Kristel and Kassel, Marlene and Dorrepaal, Ellen and Lett, Signe},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.14236},\n\tkeywords = {desiccation tolerance, frost sensitivity, mosses, relative electrolyte leakage (REL), snow manipulation experiment, tundra, winter ecology, ❓ Multiple DOI},\n\tpages = {220--232},\n}\n\n\n\n\n\n Observed climate change in northern high latitudes is strongest in winter, but still relatively little is known about the effects of winter climate change on tundra ecosystems. Ongoing changes in winter climate and snow cover will change the intensity, duration and frequency of frost events. Bryophytes form a major component of northern ecosystems but their responses to winter climate changes are largely unknown. Here, we studied how changes in overall winter climate and snow regime affect frost damage in three common bryophyte taxa that differ in desiccation tolerance in a subarctic tundra ecosystem. We used a snow manipulation experiment where bryophyte cores were transplanted from just above the tree line to similar elevation (i.e. current cold climate) and lower elevation (i.e. near-future warmer climate scenario) in Abisko, Sweden. Here, we measured frost damage in shoots of Ptilidium ciliare, Hylocomium splendens and Sphagnum fuscum with the relative electrolyte leakage (REL) method, during late winter and spring in two consecutive years. We hypothesized that frost damage would be lower in a milder climate (low site) and higher under reduced snow cover and that taxa from moister habitats with assumed low desiccation tolerance would be more sensitive to lower temperature and thinner snow cover than those from drier and more exposed habitats. Contrary to our expectations, frost damage was highest at low elevation, while the effect of snow treatment differed across sites and taxa. At the high site, frost damage was reduced under snow addition in the taxon with the assumed lowest desiccation tolerance, S. fuscum. Surprisingly, frost damage increased with mean temperature in the bryophyte core of the preceding 14 days leading up to REL measurements and decreased with higher frost degree sums, that is, was highest in the milder climate at the low site. Synthesis Our results imply that climate warming in late winter and spring increases frost damage in bryophytes. Given the high abundance of bryophytes in tundra ecosystems, higher frost damage could alter the appearance and functioning of the tundra landscape, although the short and long-term effects on bryophyte fitness remain to be studied.\n
\n\n\n\n \n\n \n \n \n \n \n \n Higher vascular plant abundance associated with decreased ecosystem respiration after 20 years of warming in the forest–tundra ecotone.\n \n \n \n \n\n\n \n Myrsky, E.; Mikola, J.; Kaarlejärvi, E.; Olofsson, J.; Sjögersten, S.; Tupek, B.; Männistö, M. K.; and Stark, S.\n\n\n \n\n\n\n Functional Ecology, 38(1): 219–232. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.14466\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{myrsky_higher_2024,\n\ttitle = {Higher vascular plant abundance associated with decreased ecosystem respiration after 20 years of warming in the forest–tundra ecotone},\n\tvolume = {38},\n\tcopyright = {© 2023 The Authors. Functional Ecology published by John Wiley \\& Sons Ltd on behalf of British Ecological Society.},\n\tissn = {1365-2435},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.14466},\n\tdoi = {10.1111/1365-2435.14466},\n\tabstract = {The on-going climate warming is promoting shrub abundance in high latitudes, but the effect of this phenomenon on ecosystem functioning is expected to depend on whether deciduous or evergreen species increase in response to warming. To explore effects of long-term warming on shrubs and further on ecosystem functioning, we analysed vegetation and ecosystem CO2 exchange after 20 years of warming in the forest–tundra ecotone in subarctic Sweden. A previous study conducted 9 years earlier had found increased evergreen Empetrum nigrum ssp. hermaphroditum in the forest and increased deciduous Betula nana in the tundra. Following current understanding, we expected continued increase in shrub abundance that would be stronger in tundra than in forest. We expected warming to increase ecosystem respiration (Re) and gross primary productivity (GPP), with a greater increase in Re in tundra due to increased deciduous shrub abundance, leading to a less negative net ecosystem exchange and reduced ecosystem C sink strength. As predicted, vascular plant abundances were higher in the warmed plots with a stronger response in tundra than in forest. However, whereas B. nana had increased in abundance since the last survey, E. hermaphroditum abundance had declined due to several moth and rodent outbreaks during the past decade. In contrast to predictions, Re was significantly lower in the warmed plots irrespective of habitat, and GPP increased marginally only in the forest. The lower Re and a higher GPP under warming in the forest together led to increased net C sink. Re was negatively associated with the total vascular plant abundance. Our results highlight the importance of disturbance regimes for vegetation responses to warming. Climate warming may promote species with both a high capacity to grow under warmer conditions and a resilience towards herbivore outbreaks. Negative correlation between Re and total vascular plant abundance further indicate that the indirect impacts of increased plants on soil microclimate may become increasingly important for ecosystem CO2 exchange in the long run, which adds to the different mechanisms that link warming and CO2 fluxes in northern ecosystems. Read the free Plain Language Summary for this article on the Journal blog.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Functional Ecology},\n\tauthor = {Myrsky, Eero and Mikola, Juha and Kaarlejärvi, Elina and Olofsson, Johan and Sjögersten, Sofie and Tupek, Boris and Männistö, Minna K. and Stark, Sari},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.14466},\n\tkeywords = {CO2 exchange, arctic greening, climate change, deciduous dwarf shrubs, evergreen dwarf shrubs, moth outbreaks, ⛔ No DOI found},\n\tpages = {219--232},\n}\n\n\n\n\n\n The on-going climate warming is promoting shrub abundance in high latitudes, but the effect of this phenomenon on ecosystem functioning is expected to depend on whether deciduous or evergreen species increase in response to warming. To explore effects of long-term warming on shrubs and further on ecosystem functioning, we analysed vegetation and ecosystem CO2 exchange after 20 years of warming in the forest–tundra ecotone in subarctic Sweden. A previous study conducted 9 years earlier had found increased evergreen Empetrum nigrum ssp. hermaphroditum in the forest and increased deciduous Betula nana in the tundra. Following current understanding, we expected continued increase in shrub abundance that would be stronger in tundra than in forest. We expected warming to increase ecosystem respiration (Re) and gross primary productivity (GPP), with a greater increase in Re in tundra due to increased deciduous shrub abundance, leading to a less negative net ecosystem exchange and reduced ecosystem C sink strength. As predicted, vascular plant abundances were higher in the warmed plots with a stronger response in tundra than in forest. However, whereas B. nana had increased in abundance since the last survey, E. hermaphroditum abundance had declined due to several moth and rodent outbreaks during the past decade. In contrast to predictions, Re was significantly lower in the warmed plots irrespective of habitat, and GPP increased marginally only in the forest. The lower Re and a higher GPP under warming in the forest together led to increased net C sink. Re was negatively associated with the total vascular plant abundance. Our results highlight the importance of disturbance regimes for vegetation responses to warming. Climate warming may promote species with both a high capacity to grow under warmer conditions and a resilience towards herbivore outbreaks. Negative correlation between Re and total vascular plant abundance further indicate that the indirect impacts of increased plants on soil microclimate may become increasingly important for ecosystem CO2 exchange in the long run, which adds to the different mechanisms that link warming and CO2 fluxes in northern ecosystems. Read the free Plain Language Summary for this article on the Journal blog.\n
\n\n\n\n \n\n \n \n \n \n \n \n Quantifying earthworm soil ingestion from changes in vertical bulk density profiles.\n \n \n \n \n\n\n \n Larsbo, M.; Koestel, J.; Krab, E. J.; and Klaminder, J.\n\n\n \n\n\n\n European Journal of Soil Biology, 120: 103574. March 2024.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n\n\n\n
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\n\n\n@article{larsbo_quantifying_2024,\n\ttitle = {Quantifying earthworm soil ingestion from changes in vertical bulk density profiles},\n\tvolume = {120},\n\tissn = {1164-5563},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1164556323001103},\n\tdoi = {10.1016/j.ejsobi.2023.103574},\n\tabstract = {Soil mixing by earthworms can have a large impact on the fate of nutrients and pollutants and on the soil's ability to sequester carbon. Nevertheless, methods to quantify earthworm ingestion and egestion under field conditions are largely lacking. Soils of the Fennoscandian tundra offer a special possibility for such quantifications, as these soils commonly lack burrowing macrofauna and exhibit a well-defined O horizon with low bulk density on top of a mineral soil with higher density. Since ingestion-egestion mixes the two soil layers, the temporal changes in the bulk density profile of such soils may be useful for estimating field ingestion rates. In this study, we applied a model for earthworm burrowing through soil ingestion to observed changes in soil densities occurring in a mesocosm experiment carried out in the arctic during four summers with intact soil. The earthworms present in the mesocosms were Aporrectodea trapezoides, Aporrectodea tuberculata, Aporrectodea rosea, Lumbricus rubellus and Lumbricus Terrestris (fourth season only). We show that changes in soil density profiles can indeed be used to infer earthworm ingestion rates that are realistic in comparison to literature values. Although uncertainties in parameter values were sometimes large, the results from this study suggest that soil turnover rates and endogeic earthworm soil ingestion rates in tundra heath and meadow soils may be as high as those reported for temperate conditions. Such large ingestion rates can explain observed large morphological changes in arctic soils where dispersing earthworms have resulted in complete inmixing of the organic layer into the mineral soil. Our approach is applicable to soil profiles with marked vertical differences in bulk density such as the soils of the Fennoscandian tundra where earthworms are currently dispersing into new areas and to layered repacked soil samples that are incubated in the field.},\n\turldate = {2024-03-26},\n\tjournal = {European Journal of Soil Biology},\n\tauthor = {Larsbo, M. and Koestel, J. and Krab, E. J. and Klaminder, J.},\n\tmonth = mar,\n\tyear = {2024},\n\tpages = {103574},\n}\n\n\n\n\n\n Soil mixing by earthworms can have a large impact on the fate of nutrients and pollutants and on the soil's ability to sequester carbon. Nevertheless, methods to quantify earthworm ingestion and egestion under field conditions are largely lacking. Soils of the Fennoscandian tundra offer a special possibility for such quantifications, as these soils commonly lack burrowing macrofauna and exhibit a well-defined O horizon with low bulk density on top of a mineral soil with higher density. Since ingestion-egestion mixes the two soil layers, the temporal changes in the bulk density profile of such soils may be useful for estimating field ingestion rates. In this study, we applied a model for earthworm burrowing through soil ingestion to observed changes in soil densities occurring in a mesocosm experiment carried out in the arctic during four summers with intact soil. The earthworms present in the mesocosms were Aporrectodea trapezoides, Aporrectodea tuberculata, Aporrectodea rosea, Lumbricus rubellus and Lumbricus Terrestris (fourth season only). We show that changes in soil density profiles can indeed be used to infer earthworm ingestion rates that are realistic in comparison to literature values. Although uncertainties in parameter values were sometimes large, the results from this study suggest that soil turnover rates and endogeic earthworm soil ingestion rates in tundra heath and meadow soils may be as high as those reported for temperate conditions. Such large ingestion rates can explain observed large morphological changes in arctic soils where dispersing earthworms have resulted in complete inmixing of the organic layer into the mineral soil. Our approach is applicable to soil profiles with marked vertical differences in bulk density such as the soils of the Fennoscandian tundra where earthworms are currently dispersing into new areas and to layered repacked soil samples that are incubated in the field.\n
\n\n\n\n \n\n \n \n \n \n \n \n Cascading effects of earthworm invasion increase graminoid density and rodent grazing intensities.\n \n \n \n \n\n\n \n Jonsson, H.; Olofsson, J.; Blume-Werry, G.; and Klaminder, J.\n\n\n \n\n\n\n Ecology, 105(2): e4212. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.4212\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{jonsson_cascading_2024,\n\ttitle = {Cascading effects of earthworm invasion increase graminoid density and rodent grazing intensities},\n\tvolume = {105},\n\tcopyright = {© 2023 The Authors. Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.},\n\tissn = {1939-9170},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ecy.4212},\n\tdoi = {10.1002/ecy.4212},\n\tabstract = {Human-mediated dispersal of non-native earthworms can cause substantial changes to the functioning and composition of ecosystems previously earthworm-free. Some of these earthworm species have the potential to “geoengineer” soils and increase plant nitrogen (N) uptake. Yet the possible consequences of increased plant N concentrations on rodent grazing remains poorly understood. In this study, we present findings from a common garden experiment with two tundra communities, meadow (forb dominated) and heath (shrub dominated), half of them subjected to 4 years of earthworm presence (Lumbricus spp. and Aporrectodea spp.). Within four summers, our earthworm treatment changed plant community composition by increasing graminoid density by, on average, 94\\% in the heath vegetation and by 49\\% in the meadow. Rodent winter grazing was more intense on plants growing in soils with earthworms, an effect that coincided with higher N concentrations in plants, indicating a higher palatability. Even though earthworms reduced soil moisture, plant community productivity, as indicated by vegetation greenness (normalized difference vegetation index), was not negatively impacted. We conclude that earthworm-induced changes in plant composition and trophic interactions may fundamentally alter the functioning of tundra ecosystems.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Ecology},\n\tauthor = {Jonsson, Hanna and Olofsson, Johan and Blume-Werry, Gesche and Klaminder, Jonatan},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.4212},\n\tkeywords = {Lumbricidae, earthworms, grazing, non-native, plant community, soil moisture, tundra, ⛔ No DOI found},\n\tpages = {e4212},\n}\n\n\n\n\n\n Human-mediated dispersal of non-native earthworms can cause substantial changes to the functioning and composition of ecosystems previously earthworm-free. Some of these earthworm species have the potential to “geoengineer” soils and increase plant nitrogen (N) uptake. Yet the possible consequences of increased plant N concentrations on rodent grazing remains poorly understood. In this study, we present findings from a common garden experiment with two tundra communities, meadow (forb dominated) and heath (shrub dominated), half of them subjected to 4 years of earthworm presence (Lumbricus spp. and Aporrectodea spp.). Within four summers, our earthworm treatment changed plant community composition by increasing graminoid density by, on average, 94% in the heath vegetation and by 49% in the meadow. Rodent winter grazing was more intense on plants growing in soils with earthworms, an effect that coincided with higher N concentrations in plants, indicating a higher palatability. Even though earthworms reduced soil moisture, plant community productivity, as indicated by vegetation greenness (normalized difference vegetation index), was not negatively impacted. We conclude that earthworm-induced changes in plant composition and trophic interactions may fundamentally alter the functioning of tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Topography and Time Shape Mire Morphometry and Large-Scale Mire Distribution Patterns in the Northern Boreal Landscape.\n \n \n \n \n\n\n \n Ehnvall, B.; Ratcliffe, J. L.; Nilsson, M. B.; Öquist, M. G.; Sponseller, R. A.; and Grabs, T.\n\n\n \n\n\n\n Journal of Geophysical Research: Earth Surface, 129(2): e2023JF007324. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2023JF007324\n\n\n\n
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\n\n\n@article{ehnvall_topography_2024,\n\ttitle = {Topography and {Time} {Shape} {Mire} {Morphometry} and {Large}-{Scale} {Mire} {Distribution} {Patterns} in the {Northern} {Boreal} {Landscape}},\n\tvolume = {129},\n\tcopyright = {© 2024. The Authors.},\n\tissn = {2169-9011},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2023JF007324},\n\tdoi = {10.1029/2023JF007324},\n\tabstract = {Peatlands are major terrestrial soil carbon stores, and open mires in boreal landscapes hold a considerable fraction of the global peat carbon. Despite decades of study, large-scale spatiotemporal analyses of mire arrangement have been scarce, which has limited our ability to scale-up mire properties, such as carbon accumulation to the landscape level. Here, we use a land-uplift mire chronosequence in northern Sweden spanning 9,000 years to quantify controls on mire distribution patterns. Our objectives include assessing changes in the spatial arrangement of mires with land surface age, and understanding modifications by upland hydrotopography. Characterizing over 3,000 mires along a 30 km transect, we found that the time since land emergence from the sea was the dominant control over mire coverage, especially for the establishment of large mire complexes. Mires at the youngest end of the chronosequence were small with heterogenous morphometry (shape, slope, and catchment-to-mire areal ratios), while mires on the oldest surfaces were variable in size, but included larger mires with more complex shapes and smaller catchment-to-mire ratios. In general, complex topography fragmented mires by constraining the lateral expansion, resulting in a greater number of mires, but reduced total mire area regardless of landscape age. Mires in this study area occurred on slopes up to 4\\%, indicating a hydrological boundary to peatland expansion under local climatic conditions. The consistency in mire responses to spatiotemporal controls illustrates how temporal limitation in peat initiation and accumulation, and topographic constraints to mire expansion together have shaped present day mire distribution patterns.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Journal of Geophysical Research: Earth Surface},\n\tauthor = {Ehnvall, B. and Ratcliffe, J. L. and Nilsson, M. B. and Öquist, M. G. and Sponseller, R. A. and Grabs, T.},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2023JF007324},\n\tkeywords = {Holocene, boreal, catchment, long-term development, mire morphometry, spatiotemporal drivers},\n\tpages = {e2023JF007324},\n}\n\n\n\n\n\n Peatlands are major terrestrial soil carbon stores, and open mires in boreal landscapes hold a considerable fraction of the global peat carbon. Despite decades of study, large-scale spatiotemporal analyses of mire arrangement have been scarce, which has limited our ability to scale-up mire properties, such as carbon accumulation to the landscape level. Here, we use a land-uplift mire chronosequence in northern Sweden spanning 9,000 years to quantify controls on mire distribution patterns. Our objectives include assessing changes in the spatial arrangement of mires with land surface age, and understanding modifications by upland hydrotopography. Characterizing over 3,000 mires along a 30 km transect, we found that the time since land emergence from the sea was the dominant control over mire coverage, especially for the establishment of large mire complexes. Mires at the youngest end of the chronosequence were small with heterogenous morphometry (shape, slope, and catchment-to-mire areal ratios), while mires on the oldest surfaces were variable in size, but included larger mires with more complex shapes and smaller catchment-to-mire ratios. In general, complex topography fragmented mires by constraining the lateral expansion, resulting in a greater number of mires, but reduced total mire area regardless of landscape age. Mires in this study area occurred on slopes up to 4%, indicating a hydrological boundary to peatland expansion under local climatic conditions. The consistency in mire responses to spatiotemporal controls illustrates how temporal limitation in peat initiation and accumulation, and topographic constraints to mire expansion together have shaped present day mire distribution patterns.\n
\n\n\n\n \n\n \n \n \n \n \n \n Using individual-based trait frequency distributions to forecast plant-pollinator network responses to environmental change.\n \n \n \n \n\n\n \n Cantwell-Jones, A.; Tylianakis, J. M.; Larson, K.; and Gill, R. J.\n\n\n \n\n\n\n Ecology Letters, 27(1): e14368. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/ele.14368\n\n\n\n
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\n\n\n@article{cantwell-jones_using_2024,\n\ttitle = {Using individual-based trait frequency distributions to forecast plant-pollinator network responses to environmental change},\n\tvolume = {27},\n\tcopyright = {Ecology Letters© 2024 The Authors. Ecology Letters published by John Wiley \\& Sons Ltd.},\n\tissn = {1461-0248},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.14368},\n\tdoi = {10.1111/ele.14368},\n\tabstract = {Determining how and why organisms interact is fundamental to understanding ecosystem responses to future environmental change. To assess the impact on plant-pollinator interactions, recent studies have examined how the effects of environmental change on individual interactions accumulate to generate species-level responses. Here, we review recent developments in using plant-pollinator networks of interacting individuals along with their functional traits, where individuals are nested within species nodes. We highlight how these individual-level, trait-based networks connect intraspecific trait variation (as frequency distributions of multiple traits) with dynamic responses within plant-pollinator communities. This approach can better explain interaction plasticity, and changes to interaction probabilities and network structure over spatiotemporal or other environmental gradients. We argue that only through appreciating such trait-based interaction plasticity can we accurately forecast the potential vulnerability of interactions to future environmental change. We follow this with general guidance on how future studies can collect and analyse high-resolution interaction and trait data, with the hope of improving predictions of future plant-pollinator network responses for targeted and effective conservation.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Ecology Letters},\n\tauthor = {Cantwell-Jones, Aoife and Tylianakis, Jason M. and Larson, Keith and Gill, Richard J.},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/ele.14368},\n\tkeywords = {environmental filtering, functional traits, global change, interactions, intraspecific variation, plasticity},\n\tpages = {e14368},\n}\n\n\n\n\n\n Determining how and why organisms interact is fundamental to understanding ecosystem responses to future environmental change. To assess the impact on plant-pollinator interactions, recent studies have examined how the effects of environmental change on individual interactions accumulate to generate species-level responses. Here, we review recent developments in using plant-pollinator networks of interacting individuals along with their functional traits, where individuals are nested within species nodes. We highlight how these individual-level, trait-based networks connect intraspecific trait variation (as frequency distributions of multiple traits) with dynamic responses within plant-pollinator communities. This approach can better explain interaction plasticity, and changes to interaction probabilities and network structure over spatiotemporal or other environmental gradients. We argue that only through appreciating such trait-based interaction plasticity can we accurately forecast the potential vulnerability of interactions to future environmental change. We follow this with general guidance on how future studies can collect and analyse high-resolution interaction and trait data, with the hope of improving predictions of future plant-pollinator network responses for targeted and effective conservation.\n
\n\n\n\n \n\n \n \n \n \n \n \n In situ seasonal patterns of root auxin concentrations and meristem length in an arctic sedge.\n \n \n \n \n\n\n \n Blume-Werry, G.; Semenchuk, P.; Ljung, K.; Milbau, A.; Novak, O.; Olofsson, J.; and Brunoni, F.\n\n\n \n\n\n\n New Phytologist, n/a(n/a): 19616. February 2024.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{blume-werry_situ_2024,\n\ttitle = {In situ seasonal patterns of root auxin concentrations and meristem length in an arctic sedge},\n\tvolume = {n/a},\n\tissn = {0028-646X},\n\turl = {https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.19616},\n\tdoi = {10.1111/nph.19616},\n\tabstract = {Summary Seasonal dynamics of root growth play an important role in large-scale ecosystem processes; they are largely governed by growth regulatory compounds and influenced by environmental conditions. Yet, our knowledge about physiological drivers of root growth is mostly limited to laboratory-based studies on model plant species. We sampled root tips of Eriophorum vaginatum and analyzed their auxin concentrations and meristem lengths biweekly over a growing season in situ in a subarctic peatland, both in surface soil and at the permafrost thawfront. Auxin concentrations were almost five times higher in surface than in thawfront soils and increased over the season, especially at the thawfront. Surprisingly, meristem length showed an opposite pattern and was almost double in thawfront compared with surface soils. Meristem length increased from peak to late season in the surface soils but decreased at the thawfront. Our study of in situ seasonal dynamics in root physiological parameters illustrates the potential for physiological methods to be applied in ecological studies and emphasizes the importance of in situ measurements. The strong effect of root location and the unexpected opposite patterns of meristem length and auxin concentrations likely show that auxin actively governs root growth to ensure a high potential for nutrient uptake at the thawfront.},\n\tnumber = {n/a},\n\turldate = {2024-03-26},\n\tjournal = {New Phytologist},\n\tauthor = {Blume-Werry, Gesche and Semenchuk, Philipp and Ljung, Karin and Milbau, Ann and Novak, Ondrej and Olofsson, Johan and Brunoni, Federica},\n\tmonth = feb,\n\tyear = {2024},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Eriophorum vaginatum, auxin, meristem length, permafrost, root growth, root phenology},\n\tpages = {19616},\n}\n\n\n\n\n\n Summary Seasonal dynamics of root growth play an important role in large-scale ecosystem processes; they are largely governed by growth regulatory compounds and influenced by environmental conditions. Yet, our knowledge about physiological drivers of root growth is mostly limited to laboratory-based studies on model plant species. We sampled root tips of Eriophorum vaginatum and analyzed their auxin concentrations and meristem lengths biweekly over a growing season in situ in a subarctic peatland, both in surface soil and at the permafrost thawfront. Auxin concentrations were almost five times higher in surface than in thawfront soils and increased over the season, especially at the thawfront. Surprisingly, meristem length showed an opposite pattern and was almost double in thawfront compared with surface soils. Meristem length increased from peak to late season in the surface soils but decreased at the thawfront. Our study of in situ seasonal dynamics in root physiological parameters illustrates the potential for physiological methods to be applied in ecological studies and emphasizes the importance of in situ measurements. The strong effect of root location and the unexpected opposite patterns of meristem length and auxin concentrations likely show that auxin actively governs root growth to ensure a high potential for nutrient uptake at the thawfront.\n
\n\n\n\n \n\n \n \n \n \n \n \n Declining calcium concentration drives shifts toward smaller and less nutritious zooplankton in northern lakes.\n \n \n \n \n\n\n \n Bergström, A.; Creed, I. F.; Paltsev, A.; de Wit, H. A.; Lau, D. C. P.; Drakare, S.; Vrede, T.; Isles, P. D. F.; Jonsson, A.; Geibrink, E.; Kortelainen, P.; Vuorenmaa, J.; Vuorio, K.; Kahilainen, K. K.; and Hessen, D. O.\n\n\n \n\n\n\n Global Change Biology, 30(3): e17220. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.17220\n\n\n\n
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\n\n\n@article{bergstrom_declining_2024,\n\ttitle = {Declining calcium concentration drives shifts toward smaller and less nutritious zooplankton in northern lakes},\n\tvolume = {30},\n\tcopyright = {© 2024 The Authors. Global Change Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.17220},\n\tdoi = {10.1111/gcb.17220},\n\tabstract = {Zooplankton community composition of northern lakes is changing due to the interactive effects of climate change and recovery from acidification, yet limited data are available to assess these changes combined. Here, we built a database using archives of temperature, water chemistry and zooplankton data from 60 Scandinavian lakes that represent broad spatial and temporal gradients in key parameters: temperature, calcium (Ca), total phosphorus (TP), total organic carbon (TOC), and pH. Using machine learning techniques, we found that Ca was the most important determinant of the relative abundance of all zooplankton groups studied, while pH was second, and TOC third in importance. Further, we found that Ca is declining in almost all lakes, and we detected a critical Ca threshold in lake water of 1.3 mg L−1, below which the relative abundance of zooplankton shifts toward dominance of Holopedium gibberum and small cladocerans at the expense of Daphnia and copepods. Our findings suggest that low Ca concentrations may shape zooplankton communities, and that current trajectories of Ca decline could promote widespread changes in pelagic food webs as zooplankton are important trophic links from phytoplankton to fish and different zooplankton species play different roles in this context.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Bergström, Ann-Kristin and Creed, Irena F. and Paltsev, Aleksey and de Wit, Heleen A. and Lau, Danny C. P. and Drakare, Stina and Vrede, Tobias and Isles, Peter D. F. and Jonsson, Anders and Geibrink, Erik and Kortelainen, Pirkko and Vuorenmaa, Jussi and Vuorio, Kristiina and Kahilainen, Kimmo K. and Hessen, Dag Olav},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.17220},\n\tkeywords = {Daphnia, Holopedium, calanoids, calcium, cladocerans, cyclopoids, lakes, phosphorus, temperature, zooplankton community composition},\n\tpages = {e17220},\n}\n\n\n\n\n\n Zooplankton community composition of northern lakes is changing due to the interactive effects of climate change and recovery from acidification, yet limited data are available to assess these changes combined. Here, we built a database using archives of temperature, water chemistry and zooplankton data from 60 Scandinavian lakes that represent broad spatial and temporal gradients in key parameters: temperature, calcium (Ca), total phosphorus (TP), total organic carbon (TOC), and pH. Using machine learning techniques, we found that Ca was the most important determinant of the relative abundance of all zooplankton groups studied, while pH was second, and TOC third in importance. Further, we found that Ca is declining in almost all lakes, and we detected a critical Ca threshold in lake water of 1.3 mg L−1, below which the relative abundance of zooplankton shifts toward dominance of Holopedium gibberum and small cladocerans at the expense of Daphnia and copepods. Our findings suggest that low Ca concentrations may shape zooplankton communities, and that current trajectories of Ca decline could promote widespread changes in pelagic food webs as zooplankton are important trophic links from phytoplankton to fish and different zooplankton species play different roles in this context.\n
\n\n\n\n \n\n \n \n \n \n \n \n Guiding downstream migrating Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) of different life stages in a large river using bubbles.\n \n \n \n \n\n\n \n Leander, J.; Hellström, G.; Nordin, J.; Jonsson, M.; and Klaminder, J.\n\n\n \n\n\n\n Rivers Research and Applications: an international journal devoted to river research and management, 40(1): 107–115. 2024.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{leander_guiding_2024,\n\ttitle = {Guiding downstream migrating {Atlantic} salmon ({Salmo} salar) and brown trout ({Salmo} trutta) of different life stages in a large river using bubbles},\n\tvolume = {40},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-186819},\n\tdoi = {10.1002/rra.4209},\n\tabstract = {Salmonid repeat spawners are precious individuals for wild populations due to their high fecundity and previous spawning experience, making them important in environmental policy. However, repeat s ...},\n\tlanguage = {eng},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Rivers Research and Applications: an international journal devoted to river research and management},\n\tauthor = {Leander, Johan and Hellström, Gustav and Nordin, Jonathan and Jonsson, Micael and Klaminder, Jonatan},\n\tyear = {2024},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tkeywords = {⛔ No DOI found},\n\tpages = {107--115},\n}\n\n\n\n\n\n Salmonid repeat spawners are precious individuals for wild populations due to their high fecundity and previous spawning experience, making them important in environmental policy. However, repeat s ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Ice-melt period dominates annual carbon dioxide evasion from clear-water Arctic lakes.\n \n \n \n \n\n\n \n Karlsson, J.; Verheijen, H. A.; Seekell, D. A.; Vachon, D.; and Klaus, M.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 9(2): 112–118. 2024.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10369\n\n\n\n
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\n\n\n@article{karlsson_ice-melt_2024,\n\ttitle = {Ice-melt period dominates annual carbon dioxide evasion from clear-water {Arctic} lakes},\n\tvolume = {9},\n\tcopyright = {© 2023 The Authors. Limnology and Oceanography Letters published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {2378-2242},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10369},\n\tdoi = {10.1002/lol2.10369},\n\tabstract = {Current estimates of carbon dioxide (CO2) evasion from Arctic lakes are highly uncertain because few studies integrate seasonal variability, specifically evasion during spring ice-melt. We quantified annual CO2 evasion for 14 clear-water Arctic lakes in Northern Sweden through mass balance (ice-melt period) and high-frequency loggers (open-water period). On average, 80\\% (SD: ± 18) of annual CO2 evasion occurred within 10 d following ice-melt. The contribution of the ice-melt period to annual CO2 evasion was high compared to earlier studies of Arctic lakes (47\\% ± 32\\%). Across all lakes, the proportion of ice-melt : annual CO2 evasion was negatively related to the dissolved organic carbon concentration and positively related to the mean depth of the lakes. The results emphasize the need for measurements of CO2 exchange at ice-melt to accurately quantify CO2 evasion from Arctic lakes.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Karlsson, J. and Verheijen, H. A. and Seekell, D. A. and Vachon, D. and Klaus, M.},\n\tyear = {2024},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10369},\n\tkeywords = {⛔ No DOI found},\n\tpages = {112--118},\n}\n\n\n\n\n\n Current estimates of carbon dioxide (CO2) evasion from Arctic lakes are highly uncertain because few studies integrate seasonal variability, specifically evasion during spring ice-melt. We quantified annual CO2 evasion for 14 clear-water Arctic lakes in Northern Sweden through mass balance (ice-melt period) and high-frequency loggers (open-water period). On average, 80% (SD: ± 18) of annual CO2 evasion occurred within 10 d following ice-melt. The contribution of the ice-melt period to annual CO2 evasion was high compared to earlier studies of Arctic lakes (47% ± 32%). Across all lakes, the proportion of ice-melt : annual CO2 evasion was negatively related to the dissolved organic carbon concentration and positively related to the mean depth of the lakes. The results emphasize the need for measurements of CO2 exchange at ice-melt to accurately quantify CO2 evasion from Arctic lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Taking the beat of the Arctic: are lemming population cycles changing due to winter climate?.\n \n \n \n \n\n\n \n Gauthier, G.; Ehrich, D.; Belke-Brea, M.; Domine, F.; Alisauskas, R.; Clark, K.; Ecke, F.; Eide, N. E.; Framstad, E.; Frandsen, J.; Gilg, O.; Henttonen, H.; Hörnfeldt, B.; Kataev, G. D.; Menyushina, I. E.; Oksanen, L.; Oksanen, T.; Olofsson, J.; Samelius, G.; Sittler, B.; Smith, P. A.; Sokolov, A. A.; Sokolova, N. A.; and Schmidt, N. M.\n\n\n \n\n\n\n Proceedings of the Royal Society B: Biological Sciences, 291(2016): 20232361. February 2024.\n Publisher: Royal Society\n\n\n\n
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\n\n\n@article{gauthier_taking_2024,\n\ttitle = {Taking the beat of the {Arctic}: are lemming population cycles changing due to winter climate?},\n\tvolume = {291},\n\tshorttitle = {Taking the beat of the {Arctic}},\n\turl = {https://royalsocietypublishing.org/doi/10.1098/rspb.2023.2361},\n\tdoi = {10.1098/rspb.2023.2361},\n\tabstract = {Reports of fading vole and lemming population cycles and persisting low populations in some parts of the Arctic have raised concerns about the spread of these fundamental changes to tundra food web dynamics. By compiling 24 unique time series of lemming population fluctuations across the circumpolar region, we show that virtually all populations displayed alternating periods of cyclic/non-cyclic fluctuations over the past four decades. Cyclic patterns were detected 55\\% of the time (n = 649 years pooled across sites) with a median periodicity of 3.7 years, and non-cyclic periods were not more frequent in recent years. Overall, there was an indication for a negative effect of warm spells occurring during the snow onset period of the preceding year on lemming abundance. However, winter duration or early winter climatic conditions did not differ on average between cyclic and non-cyclic periods. Analysis of the time series shows that there is presently no Arctic-wide collapse of lemming cycles, even though cycles have been sporadic at most sites during the last decades. Although non-stationary dynamics appears a common feature of lemming populations also in the past, continued warming in early winter may decrease the frequency of periodic irruptions with negative consequences for tundra ecosystems.},\n\tnumber = {2016},\n\turldate = {2024-03-26},\n\tjournal = {Proceedings of the Royal Society B: Biological Sciences},\n\tauthor = {Gauthier, Gilles and Ehrich, Dorothée and Belke-Brea, Maria and Domine, Florent and Alisauskas, Ray and Clark, Karin and Ecke, Frauke and Eide, Nina E. and Framstad, Erik and Frandsen, Jay and Gilg, Olivier and Henttonen, Heikki and Hörnfeldt, Birger and Kataev, Gennadiy D. and Menyushina, Irina E. and Oksanen, Lauri and Oksanen, Tarja and Olofsson, Johan and Samelius, Gustaf and Sittler, Benoit and Smith, Paul A. and Sokolov, Aleksandr A. and Sokolova, Natalia A. and Schmidt, Niels M.},\n\tmonth = feb,\n\tyear = {2024},\n\tnote = {Publisher: Royal Society},\n\tkeywords = {Arctic tundra, climate warming, melt–freeze events, population dynamics, small mammals, transient dynamics},\n\tpages = {20232361},\n}\n\n\n\n\n\n Reports of fading vole and lemming population cycles and persisting low populations in some parts of the Arctic have raised concerns about the spread of these fundamental changes to tundra food web dynamics. By compiling 24 unique time series of lemming population fluctuations across the circumpolar region, we show that virtually all populations displayed alternating periods of cyclic/non-cyclic fluctuations over the past four decades. Cyclic patterns were detected 55% of the time (n = 649 years pooled across sites) with a median periodicity of 3.7 years, and non-cyclic periods were not more frequent in recent years. Overall, there was an indication for a negative effect of warm spells occurring during the snow onset period of the preceding year on lemming abundance. However, winter duration or early winter climatic conditions did not differ on average between cyclic and non-cyclic periods. Analysis of the time series shows that there is presently no Arctic-wide collapse of lemming cycles, even though cycles have been sporadic at most sites during the last decades. Although non-stationary dynamics appears a common feature of lemming populations also in the past, continued warming in early winter may decrease the frequency of periodic irruptions with negative consequences for tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Short- and long-term plant and microbial uptake of 15N-labelled urea in a mesic tundra heath, West Greenland.\n \n \n \n \n\n\n \n Barthelemy, H.; Nobel, L. A.; Stark, S.; Väisänen, M.; Olofsson, J.; and Michelsen, A.\n\n\n \n\n\n\n Polar Biology, 47(1): 1–15. 2024.\n Publisher: Springer Nature\n\n\n\n
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\n\n\n@article{barthelemy_short-_2024,\n\ttitle = {Short- and long-term plant and microbial uptake of {15N}-labelled urea in a mesic tundra heath, {West} {Greenland}},\n\tvolume = {47},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-216900},\n\tdoi = {10.1007/s00300-023-03209-6},\n\tabstract = {Terrestrial animals are key elements in the cycling of elements in the Arctic where nutrient availability is low. Waste production by herbivores, in particular urine deposition, has a crucial role ...},\n\tlanguage = {eng},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Polar Biology},\n\tauthor = {Barthelemy, Hélène and Nobel, Liv Alexa and Stark, Sari and Väisänen, Maria and Olofsson, Johan and Michelsen, Anders},\n\tyear = {2024},\n\tnote = {Publisher: Springer Nature},\n\tpages = {1--15},\n}\n\n\n\n\n\n Terrestrial animals are key elements in the cycling of elements in the Arctic where nutrient availability is low. Waste production by herbivores, in particular urine deposition, has a crucial role ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Extreme drought impacts have been underestimated in grasslands and shrublands globally.\n \n \n \n \n\n\n \n Smith, M. D.; Wilkins, K. D.; Holdrege, M. C.; Wilfahrt, P.; Collins, S. L.; Knapp, A. K.; Sala, O. E.; Dukes, J. S.; Phillips, R. P.; and Yahdjian, L.\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences, 121(4): e2309881120. 2024.\n Publisher: National Acad Sciences\n\n\n\n
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\n\n\n\n@article{smith_extreme_2024,\n\ttitle = {Extreme drought impacts have been underestimated in grasslands and shrublands globally},\n\tvolume = {121},\n\turl = {https://www.pnas.org/doi/abs/10.1073/pnas.2309881120},\n\tdoi = {10.1073/pnas.2309881120},\n\tnumber = {4},\n\turldate = {2024-03-26},\n\tjournal = {Proceedings of the National Academy of Sciences},\n\tauthor = {Smith, Melinda D. and Wilkins, Kate D. and Holdrege, Martin C. and Wilfahrt, Peter and Collins, Scott L. and Knapp, Alan K. and Sala, Osvaldo E. and Dukes, Jeffrey S. and Phillips, Richard P. and Yahdjian, Laura},\n\tyear = {2024},\n\tnote = {Publisher: National Acad Sciences},\n\tpages = {e2309881120},\n}\n\n\n\n\n\n
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\n \n \n\n \n \n \n \n \n \n The ecosystem effects of reindeer (Rangifer tarandus) in northern Fennoscandia: Past, present and future.\n \n \n \n \n\n\n \n Stark, S.; Horstkotte, T.; Kumpula, J.; Olofsson, J.; Tømmervik, H.; and Turunen, M.\n\n\n \n\n\n\n Perspectives in Plant Ecology, Evolution and Systematics, 58: 125716. March 2023.\n \n\n\n\n
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\n\n\n@article{stark_ecosystem_2023,\n\ttitle = {The ecosystem effects of reindeer ({Rangifer} tarandus) in northern {Fennoscandia}: {Past}, present and future},\n\tvolume = {58},\n\tissn = {1433-8319},\n\tshorttitle = {The ecosystem effects of reindeer (\\textit{{Rangifer} tarandus}) in northern {Fennoscandia}},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1433831922000580},\n\tdoi = {10.1016/j.ppees.2022.125716},\n\tabstract = {The semi-domesticated nature of the reindeer (Rangifer tarandus L.) makes it a distinct case among the world’s herbivores. Here, we review the literature on how reindeer shape vegetation and soil carbon and nitrogen cycles in northernmost Fennoscandia. We first describe main historical events that shaped the present-day grazing patterns in the different countries, then discuss the methodological considerations needed for interpreting evidence from grazer exclosures in ecological and environmental contexts. We argue that it is critical to be aware that these experiments do not measure the effect of grazing per se, but rather, they measure the responses of existing ecosystem structure and function to the sudden cessation of grazing in an environment, which was to a large degree shaped by it. Studies show that the direction and the magnitude of the effects of reindeer on vegetation and soil processes vary across habitats and depend on both the current land-uses and the historically formed grazing regimes; knowledge of the history is thus a key prerequisite for understanding the role of reindeer in ecosystems. As a general trend, reindeer affect soil nutrient cycles to a stronger extent in subarctic than in boreal ecosystems. In sites where reindeer have changed soil nutrient availability, they indirectly modify vegetation and productivity even after the cessation of grazing. We reason that the concepts of cultural and natural landscapes are not mutually exclusive in the case of reindeer ranges. Understanding how the intensity and seasonal timing of both past and present grazing direct ecosystem changes under climate warming is crucial for predicting future ecosystem structures and functioning in northern Fennoscandia as well as ecosystems in general.},\n\turldate = {2024-03-27},\n\tjournal = {Perspectives in Plant Ecology, Evolution and Systematics},\n\tauthor = {Stark, Sari and Horstkotte, Tim and Kumpula, Jouko and Olofsson, Johan and Tømmervik, Hans and Turunen, Minna},\n\tmonth = mar,\n\tyear = {2023},\n\tkeywords = {Boreal forests, Grazing, Mountain birch, Soil Nutrient Cycling, Tundra heath, Ungulate},\n\tpages = {125716},\n}\n\n\n\n\n\n The semi-domesticated nature of the reindeer (Rangifer tarandus L.) makes it a distinct case among the world’s herbivores. Here, we review the literature on how reindeer shape vegetation and soil carbon and nitrogen cycles in northernmost Fennoscandia. We first describe main historical events that shaped the present-day grazing patterns in the different countries, then discuss the methodological considerations needed for interpreting evidence from grazer exclosures in ecological and environmental contexts. We argue that it is critical to be aware that these experiments do not measure the effect of grazing per se, but rather, they measure the responses of existing ecosystem structure and function to the sudden cessation of grazing in an environment, which was to a large degree shaped by it. Studies show that the direction and the magnitude of the effects of reindeer on vegetation and soil processes vary across habitats and depend on both the current land-uses and the historically formed grazing regimes; knowledge of the history is thus a key prerequisite for understanding the role of reindeer in ecosystems. As a general trend, reindeer affect soil nutrient cycles to a stronger extent in subarctic than in boreal ecosystems. In sites where reindeer have changed soil nutrient availability, they indirectly modify vegetation and productivity even after the cessation of grazing. We reason that the concepts of cultural and natural landscapes are not mutually exclusive in the case of reindeer ranges. Understanding how the intensity and seasonal timing of both past and present grazing direct ecosystem changes under climate warming is crucial for predicting future ecosystem structures and functioning in northern Fennoscandia as well as ecosystems in general.\n
\n\n\n\n \n\n \n \n \n \n \n \n Investigating the diet source influence on freshwater fish mercury bioaccumulation and fatty acids—Experiences from Swedish lakes and Chinese reservoirs.\n \n \n \n \n\n\n \n Wu, P.; Yan, H.; Kainz, M. J.; Branfireun, B.; Bergström, A.; Jing, M.; and Bishop, K.\n\n\n \n\n\n\n Ecotoxicology. November 2023.\n \n\n\n\n
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\n\n\n@article{wu_investigating_2023,\n\ttitle = {Investigating the diet source influence on freshwater fish mercury bioaccumulation and fatty acids—{Experiences} from {Swedish} lakes and {Chinese} reservoirs},\n\tissn = {1573-3017},\n\turl = {https://doi.org/10.1007/s10646-023-02712-0},\n\tdoi = {10.1007/s10646-023-02712-0},\n\tabstract = {Dietary uptake is key for transferring potentially toxic contaminants, such as mercury (Hg) and essential dietary nutrients, such as polyunsaturated fatty acids (PUFA), to consumers at higher trophic levels of aquatic food webs. We evaluated the role of diet sources for Hg bioaccumulation and PUFA retention in fish across lake food webs in seven Swedish lakes and two Chinese reservoirs. Fish total Hg (THg) and methyl-Hg (MeHg) differed greatly between the two countries: the Chinese fish contained less than 300 ng g−1 dry weight (d.w.) THg with less than 50\\% as MeHg, versus the Swedish fishes which contained approximately 2000 ng g−1 d.w. THg and nearly 100\\% as MeHg. Fatty acids enrichment of linoleic acids (LIN) were more prevalent in the Chinese fishes regardless of size (p {\\textless} 0.05). Here we examined food web length, fish growth rates, and fatty acids patterns in relation to the quality of fish as a food source for both Hg and FA. Contrary to the expectation that biodilution of Hg throughout the food chain would explain these differences, a more complex picture emerged with high levels of Hg at the base of the food web in the Chinese reservoirs, a decoupling of fatty acid and Hg bioaccumulation, and a major role for both fish stocking and fish feed. It is hoped that this work will provide a nuanced picture of fish quality as a food source in different ecosystems.},\n\tlanguage = {en},\n\turldate = {2024-03-27},\n\tjournal = {Ecotoxicology},\n\tauthor = {Wu, Pianpian and Yan, Haiyu and Kainz, Martin J. and Branfireun, Brian and Bergström, Ann-Kristin and Jing, Min and Bishop, Kevin},\n\tmonth = nov,\n\tyear = {2023},\n}\n\n\n\n\n\n Dietary uptake is key for transferring potentially toxic contaminants, such as mercury (Hg) and essential dietary nutrients, such as polyunsaturated fatty acids (PUFA), to consumers at higher trophic levels of aquatic food webs. We evaluated the role of diet sources for Hg bioaccumulation and PUFA retention in fish across lake food webs in seven Swedish lakes and two Chinese reservoirs. Fish total Hg (THg) and methyl-Hg (MeHg) differed greatly between the two countries: the Chinese fish contained less than 300 ng g−1 dry weight (d.w.) THg with less than 50% as MeHg, versus the Swedish fishes which contained approximately 2000 ng g−1 d.w. THg and nearly 100% as MeHg. Fatty acids enrichment of linoleic acids (LIN) were more prevalent in the Chinese fishes regardless of size (p \\textless 0.05). Here we examined food web length, fish growth rates, and fatty acids patterns in relation to the quality of fish as a food source for both Hg and FA. Contrary to the expectation that biodilution of Hg throughout the food chain would explain these differences, a more complex picture emerged with high levels of Hg at the base of the food web in the Chinese reservoirs, a decoupling of fatty acid and Hg bioaccumulation, and a major role for both fish stocking and fish feed. It is hoped that this work will provide a nuanced picture of fish quality as a food source in different ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Decreased Soil Microbial Nitrogen Under Vegetation ‘Shrubification’ in the Subarctic Forest–Tundra Ecotone: The Potential Role of Increasing Nutrient Competition Between Plants and Soil Microorganisms.\n \n \n \n \n\n\n \n Stark, S.; Kumar, M.; Myrsky, E.; Vuorinen, J.; Kantola, A. M.; Telkki, V.; Sjögersten, S.; Olofsson, J.; and Männistö, M. K.\n\n\n \n\n\n\n Ecosystems, 26(7): 1504–1523. November 2023.\n \n\n\n\n
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\n\n\n@article{stark_decreased_2023,\n\ttitle = {Decreased {Soil} {Microbial} {Nitrogen} {Under} {Vegetation} ‘{Shrubification}’ in the {Subarctic} {Forest}–{Tundra} {Ecotone}: {The} {Potential} {Role} of {Increasing} {Nutrient} {Competition} {Between} {Plants} and {Soil} {Microorganisms}},\n\tvolume = {26},\n\tissn = {1435-0629},\n\tshorttitle = {Decreased {Soil} {Microbial} {Nitrogen} {Under} {Vegetation} ‘{Shrubification}’ in the {Subarctic} {Forest}–{Tundra} {Ecotone}},\n\turl = {https://doi.org/10.1007/s10021-023-00847-z},\n\tdoi = {10.1007/s10021-023-00847-z},\n\tabstract = {The consequences of warming-induced ‘shrubification’ on Arctic soil carbon storage are receiving increased attention, as the majority of ecosystem carbon in these systems is stored in soils. Soil carbon cycles in these ecosystems are usually tightly coupled with nitrogen availability. Soil microbial responses to ‘shrubification’ may depend on the traits of the shrub species that increase in response to warming. Increase in deciduous shrubs such as Betula nana likely promotes a loss of soil carbon, whereas the opposite may be true if evergreen shrubs such as Empetrum hermaphroditum increase. We analyzed soil organic matter stocks and 13C NMR fractions, microbial CO2 respiration, biomass, extracellular enzyme activities (EEAs), and their association with shrub density in northern Sweden after 20 years of experimental warming using open top chambers (OTCs). Our study sites were located in a tundra heath that stores high soil carbon quantities and where the OTCs had increased deciduous shrubs, and in a mountain birch forest that stores lower soil carbon quantities and where the OTCs had increased evergreen shrubs. We predicted that organic matter stocks should be lower and respiration and EEAs higher inside the OTCs than untreated plots in the tundra, whereas no effect should be detected in the forest. Soil organic matter stocks and 13C NMR fractions remained unaffected at both sites. When expressed as per gram microbial biomass, respiration and EEAs for carbohydrate and chitin degradation were higher inside the OTCs, and contrasting our prediction, this effect was stronger in the forest. Unexpectedly, the OTCs also led to a substantially lower microbial biomass carbon and nitrogen irrespective of habitat. The decline in the microbial biomass counteracted increased activities resulting in no effect of the OTCs on respiration and a lower phenol oxidase activity per gram soil. Microbial biomass nitrogen correlated negatively with evergreen shrub density at both sites, indicating that ‘shrubification’ may have intensified nutrient competition between plants and soil microorganisms. Nutrient limitation could also underlie increased respiration per gram microbial biomass through limiting C assimilation into biomass. We hypothesize that increasing nutrient immobilization into long-lived evergreen shrubs could over time induce microbial nutrient limitation that contributes to a stability of accumulated soil organic matter stocks under climate warming.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Stark, Sari and Kumar, Manoj and Myrsky, Eero and Vuorinen, Jere and Kantola, Anu M. and Telkki, Ville-Veikko and Sjögersten, Sofie and Olofsson, Johan and Männistö, Minna K.},\n\tmonth = nov,\n\tyear = {2023},\n\tkeywords = {\\#nosource, CO2 release, Empetrum hermaphroditum, climate warming, extracellular enzymes, mountain birch forest, soil organic matter, tundra heath},\n\tpages = {1504--1523},\n}\n\n\n\n\n\n The consequences of warming-induced ‘shrubification’ on Arctic soil carbon storage are receiving increased attention, as the majority of ecosystem carbon in these systems is stored in soils. Soil carbon cycles in these ecosystems are usually tightly coupled with nitrogen availability. Soil microbial responses to ‘shrubification’ may depend on the traits of the shrub species that increase in response to warming. Increase in deciduous shrubs such as Betula nana likely promotes a loss of soil carbon, whereas the opposite may be true if evergreen shrubs such as Empetrum hermaphroditum increase. We analyzed soil organic matter stocks and 13C NMR fractions, microbial CO2 respiration, biomass, extracellular enzyme activities (EEAs), and their association with shrub density in northern Sweden after 20 years of experimental warming using open top chambers (OTCs). Our study sites were located in a tundra heath that stores high soil carbon quantities and where the OTCs had increased deciduous shrubs, and in a mountain birch forest that stores lower soil carbon quantities and where the OTCs had increased evergreen shrubs. We predicted that organic matter stocks should be lower and respiration and EEAs higher inside the OTCs than untreated plots in the tundra, whereas no effect should be detected in the forest. Soil organic matter stocks and 13C NMR fractions remained unaffected at both sites. When expressed as per gram microbial biomass, respiration and EEAs for carbohydrate and chitin degradation were higher inside the OTCs, and contrasting our prediction, this effect was stronger in the forest. Unexpectedly, the OTCs also led to a substantially lower microbial biomass carbon and nitrogen irrespective of habitat. The decline in the microbial biomass counteracted increased activities resulting in no effect of the OTCs on respiration and a lower phenol oxidase activity per gram soil. Microbial biomass nitrogen correlated negatively with evergreen shrub density at both sites, indicating that ‘shrubification’ may have intensified nutrient competition between plants and soil microorganisms. Nutrient limitation could also underlie increased respiration per gram microbial biomass through limiting C assimilation into biomass. We hypothesize that increasing nutrient immobilization into long-lived evergreen shrubs could over time induce microbial nutrient limitation that contributes to a stability of accumulated soil organic matter stocks under climate warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Erosion regime controls sediment environmental DNA-based community reconstruction.\n \n \n \n \n\n\n \n Morlock, M. A.; Rodriguez-Martinez, S.; Huang, D. Y.; and Klaminder, J.\n\n\n \n\n\n\n Environmental DNA, 5(6): 1393–1404. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/edn3.458\n\n\n\n
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\n\n\n@article{morlock_erosion_2023,\n\ttitle = {Erosion regime controls sediment environmental {DNA}-based community reconstruction},\n\tvolume = {5},\n\tcopyright = {© 2023 The Authors. Environmental DNA published by John Wiley \\& Sons Ltd.},\n\tissn = {2637-4943},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/edn3.458},\n\tdoi = {10.1002/edn3.458},\n\tabstract = {Analysis of environmental DNA detected in lake sediments shows promise to become a great paleoecological technique that can provide detailed information about organism communities living in past environments. However, when interpreting sedimentary environmental DNA records, it is of crucial importance to separate ecosystem responses to large-scale environmental change from “noise” caused by changes in sediment provenance or potential post-depositional DNA mobility. In this study, we show that plant and mammalian communities reconstructed from sediments are strongly affected by sediment provenance, but unaffected by vertical mobility of DNA after sediment deposition. We observe that DNA from aquatic plants was abundant in background sediment, while embedded detrital event layers (sediment deposited under erosion events) primarily contained terrestrial plants; hence, vertical mobility of aquatic plant DNA across sediment layers was negligible within our studied lakes. About 33\\% of the identified terrestrial plant genera were only found in detrital sediment, suggesting that sediment origin had a strong impact on the reconstructed plant community. Similarly, DNA of some mammalian taxa (Capra hircus, Ursus arctos, Lepus, and Felis) were only or preferentially found in detrital event layers. Temporal changes across the Holocene were the main drivers of change for reconstructed plant communities, but sediment type was the second most important factor of variance. Our results highlight that erosion and sediment provenance need to be considered when reconstructing past mammalian and plant communities using environmental DNA from lake sediments.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Environmental DNA},\n\tauthor = {Morlock, Marina A. and Rodriguez-Martinez, Saúl and Huang, Doreen Yu-Tuan and Klaminder, Jonatan},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/edn3.458},\n\tkeywords = {DNA taphonomy, Lake Grosssee, Switzerland, erosion, lake sediment, paleoecology, sedaDNA},\n\tpages = {1393--1404},\n}\n\n\n\n\n\n Analysis of environmental DNA detected in lake sediments shows promise to become a great paleoecological technique that can provide detailed information about organism communities living in past environments. However, when interpreting sedimentary environmental DNA records, it is of crucial importance to separate ecosystem responses to large-scale environmental change from “noise” caused by changes in sediment provenance or potential post-depositional DNA mobility. In this study, we show that plant and mammalian communities reconstructed from sediments are strongly affected by sediment provenance, but unaffected by vertical mobility of DNA after sediment deposition. We observe that DNA from aquatic plants was abundant in background sediment, while embedded detrital event layers (sediment deposited under erosion events) primarily contained terrestrial plants; hence, vertical mobility of aquatic plant DNA across sediment layers was negligible within our studied lakes. About 33% of the identified terrestrial plant genera were only found in detrital sediment, suggesting that sediment origin had a strong impact on the reconstructed plant community. Similarly, DNA of some mammalian taxa (Capra hircus, Ursus arctos, Lepus, and Felis) were only or preferentially found in detrital event layers. Temporal changes across the Holocene were the main drivers of change for reconstructed plant communities, but sediment type was the second most important factor of variance. Our results highlight that erosion and sediment provenance need to be considered when reconstructing past mammalian and plant communities using environmental DNA from lake sediments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Landscape of ice and fire – uniquely well-preserved Scots pine trunks reveal forest fires near the retreating Weichselian ice margin.\n \n \n \n \n\n\n \n Klaminder, J.; Fassl, M.; Baudet, M.; Östlund, L.; Linderholm, J.; and Zale, R.\n\n\n \n\n\n\n Vegetation History and Archaeobotany, 1. December 2023.\n \n\n\n\n
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\n\n\n@article{klaminder_landscape_2023,\n\ttitle = {Landscape of ice and fire – uniquely well-preserved {Scots} pine trunks reveal forest fires near the retreating {Weichselian} ice margin},\n\tvolume = {1},\n\tissn = {1617-6278},\n\turl = {https://doi.org/10.1007/s00334-023-00974-6},\n\tdoi = {10.1007/s00334-023-00974-6},\n\tabstract = {Environmental conditions for trees that established in central Fennoscandia shortly after the final retreat of the Weichselian ice sheet remain poorly understood. In this study we examine tree rings of five well-preserved Pinus sylvestris (Scots pines) that grew in the area in front of the retreating ice sheet in northern Sweden. They became buried in flood sediments deposited by a glacial outburst flood (jökulhlaup) about 9.5–9.9 kyr cal bp and the aim of our study was to search for information regarding damage from fires and bioclimatic conditions in their ancient tree ring records. Our analysis, providing a glimpse into the local early Holocene environment in north-central Sweden, suggests that: 1, there were repeated fires (four fire events detected) during the early Holocene; and 2, bioclimatic conditions when the ancient pines were growing resembled those of modern sub-alpine pine woods. The latter is indicated by their patterns of tree ring growth (growth rate and variation), which were statistically similar to those of pines growing in sub-alpine woods with an open canopy, but different from pines in protected and managed boreal forests. Lower δ13C for the ancient latewood in comparison to pine wood from trees growing near the Scandinavian mountains before the 1850s were probably caused both by stomata fractionation due to lower atmospheric CO2 during the early Holocene and by the moist local environment created by the nearby ancient Ancylus lake, which preceded the Baltic Sea. Periods with cloudy and cold summers were also indicated by the occurrence of ‘false rings’. Finds of charred fragments of Calluna vulgaris (heather, ling), an understory shrub that can burn even with a relatively high moisture content, suggest that heath vegetation was crucial to make fire a reoccurring ecological factor in the area during the early Holocene.},\n\tlanguage = {en},\n\turldate = {2024-03-27},\n\tjournal = {Vegetation History and Archaeobotany},\n\tauthor = {Klaminder, Jonatan and Fassl, Magdalena and Baudet, Marlène and Östlund, Lars and Linderholm, Johan and Zale, Rolf},\n\tmonth = dec,\n\tyear = {2023},\n\tkeywords = {Climate, Early Holocene, Forest fires, Forest history, Lycksele, Pinus sylvestris},\n}\n\n\n\n\n\n Environmental conditions for trees that established in central Fennoscandia shortly after the final retreat of the Weichselian ice sheet remain poorly understood. In this study we examine tree rings of five well-preserved Pinus sylvestris (Scots pines) that grew in the area in front of the retreating ice sheet in northern Sweden. They became buried in flood sediments deposited by a glacial outburst flood (jökulhlaup) about 9.5–9.9 kyr cal bp and the aim of our study was to search for information regarding damage from fires and bioclimatic conditions in their ancient tree ring records. Our analysis, providing a glimpse into the local early Holocene environment in north-central Sweden, suggests that: 1, there were repeated fires (four fire events detected) during the early Holocene; and 2, bioclimatic conditions when the ancient pines were growing resembled those of modern sub-alpine pine woods. The latter is indicated by their patterns of tree ring growth (growth rate and variation), which were statistically similar to those of pines growing in sub-alpine woods with an open canopy, but different from pines in protected and managed boreal forests. Lower δ13C for the ancient latewood in comparison to pine wood from trees growing near the Scandinavian mountains before the 1850s were probably caused both by stomata fractionation due to lower atmospheric CO2 during the early Holocene and by the moist local environment created by the nearby ancient Ancylus lake, which preceded the Baltic Sea. Periods with cloudy and cold summers were also indicated by the occurrence of ‘false rings’. Finds of charred fragments of Calluna vulgaris (heather, ling), an understory shrub that can burn even with a relatively high moisture content, suggest that heath vegetation was crucial to make fire a reoccurring ecological factor in the area during the early Holocene.\n
\n\n\n\n \n\n \n \n \n \n \n \n Tundra cryogenic land surface processes and CO2–C balance in sub-Arctic alpine environment withstand winter and spring warming.\n \n \n \n \n\n\n \n Väisänen, M.; Klaminder, J.; Ylänne, H.; Teuber, L.; Dorrepaal, E.; and Krab, E. J.\n\n\n \n\n\n\n Environmental Research: Climate, 2(2): 021001. March 2023.\n Publisher: IOP Publishing\n\n\n\n
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\n\n\n@article{vaisanen_tundra_2023,\n\ttitle = {Tundra cryogenic land surface processes and {CO2}–{C} balance in sub-{Arctic} alpine environment withstand winter and spring warming},\n\tvolume = {2},\n\tissn = {2752-5295},\n\turl = {https://dx.doi.org/10.1088/2752-5295/acc08b},\n\tdoi = {10.1088/2752-5295/acc08b},\n\tabstract = {Cryogenic land surface processes (CLSPs), such as cryoturbation, are currently active in landscapes covering 25\\% of our planet where they dictate key functions, such as carbon (C) cycling, and maintain patterned landscape features. While CLSPs are expected to diminish in the near future due to milder winters especially in the southern parts of the Arctic, the shifts in C cycling in these landscapes may be more complex, since climate change can affect C cycling directly but also indirectly via CLSPs. Here, we study the effects of changing winter and spring climate on CLSPs and C cycling in non-sorted circles consisting of barren frost boils and their vegetated rims. We do this by measuring cryoturbation and ecosystem CO2 fluxes repeatedly in alpine subarctic tundra where temperatures during naturally snow covered period have been experimentally increased with snow-trapping fences and temperatures during winter and spring period after snowmelt have been increased with insulating fleeces. Opposite to our hypothesis, warming treatments did not decrease cryoturbation. However, winter warming via deeper snow increased ecosystem C sink during summer by decreasing ecosystem CO2 release in the frost boils and by counterbalancing the negative effects of cryoturbation on plant CO2 uptake in the vegetated rims. Our results suggest that short-term changes in winter and spring climate may not alter cryoturbation and jeopardize the tundra C sink.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {Environmental Research: Climate},\n\tauthor = {Väisänen, Maria and Klaminder, Jonatan and Ylänne, Henni and Teuber, Laurenz and Dorrepaal, Ellen and Krab, Eveline J.},\n\tmonth = mar,\n\tyear = {2023},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {021001},\n}\n\n\n\n\n\n Cryogenic land surface processes (CLSPs), such as cryoturbation, are currently active in landscapes covering 25% of our planet where they dictate key functions, such as carbon (C) cycling, and maintain patterned landscape features. While CLSPs are expected to diminish in the near future due to milder winters especially in the southern parts of the Arctic, the shifts in C cycling in these landscapes may be more complex, since climate change can affect C cycling directly but also indirectly via CLSPs. Here, we study the effects of changing winter and spring climate on CLSPs and C cycling in non-sorted circles consisting of barren frost boils and their vegetated rims. We do this by measuring cryoturbation and ecosystem CO2 fluxes repeatedly in alpine subarctic tundra where temperatures during naturally snow covered period have been experimentally increased with snow-trapping fences and temperatures during winter and spring period after snowmelt have been increased with insulating fleeces. Opposite to our hypothesis, warming treatments did not decrease cryoturbation. However, winter warming via deeper snow increased ecosystem C sink during summer by decreasing ecosystem CO2 release in the frost boils and by counterbalancing the negative effects of cryoturbation on plant CO2 uptake in the vegetated rims. Our results suggest that short-term changes in winter and spring climate may not alter cryoturbation and jeopardize the tundra C sink.\n
\n\n\n\n \n\n \n \n \n \n \n \n Earthworm-Driven Changes in Soil Chemico-Physical Properties, Soil Bacterial Microbiota, Tree/Tea Litter Decomposition, and Plant Growth in a Mesocosm Experiment with Two Plant Species.\n \n \n \n \n\n\n \n Sofo, A.; Khanghahi, M. Y.; Curci, M.; Reyes, F.; Briones, M. J. I.; Sarneel, J. M.; Cardinale, D.; and Crecchio, C.\n\n\n \n\n\n\n Plants, 12(6): 1216. January 2023.\n Number: 6 Publisher: Multidisciplinary Digital Publishing Institute\n\n\n\n
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\n\n\n@article{sofo_earthworm-driven_2023,\n\ttitle = {Earthworm-{Driven} {Changes} in {Soil} {Chemico}-{Physical} {Properties}, {Soil} {Bacterial} {Microbiota}, {Tree}/{Tea} {Litter} {Decomposition}, and {Plant} {Growth} in a {Mesocosm} {Experiment} with {Two} {Plant} {Species}},\n\tvolume = {12},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\tissn = {2223-7747},\n\turl = {https://www.mdpi.com/2223-7747/12/6/1216},\n\tdoi = {10.3390/plants12061216},\n\tabstract = {Earthworms and soil microorganisms contribute to soil health, quality, and fertility, but their importance in agricultural soils is often underestimated. This study aims at examining whether and to what extent the presence of earthworms (Eisenia sp.) affected the (a) soil bacterial community composition, (b) litter decomposition, and (c) plant growth (Brassica oleracea L., broccoli; Vicia faba L., faba bean). We performed a mesocosm experiment in which plants were grown outdoors for four months with or without earthworms. Soil bacterial community structure was evaluated by a 16S rRNA-based metabarcoding approach. Litter decomposition rates were determined by using the tea bag index (TBI) and litter bags (olive residues). Earthworm numbers almost doubled throughout the experimental period. Independently of the plant species, earthworm presence had a significant impact on the structure of soil bacterial community, in terms of enhanced α- and β-diversity (especially that of Proteobacteria, Bacteroidota, Myxococcota, and Verrucomicrobia) and increased 16S rRNA gene abundance (+89\\% in broccoli and +223\\% in faba bean). Microbial decomposition (TBI) was enhanced in the treatments with earthworms, and showed a significantly higher decomposition rate constant (kTBI) and a lower stabilization factor (STBI), whereas decomposition in the litter bags (dlitter) increased by about 6\\% in broccoli and 5\\% in faba bean. Earthworms significantly enhanced root growth (in terms of total length and fresh weight) of both plant species. Our results show the strong influence of earthworms and crop identity in shaping soil chemico-physical properties, soil bacterial community, litter decomposition and plant growth. These findings could be used for developing nature-based solutions that ensure the long-term biological sustainability of soil agro- and natural ecosystems.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Plants},\n\tauthor = {Sofo, Adriano and Khanghahi, Mohammad Yaghoubi and Curci, Maddalena and Reyes, Francesco and Briones, Maria J. I. and Sarneel, Judith M. and Cardinale, Domenico and Crecchio, Carmine},\n\tmonth = jan,\n\tyear = {2023},\n\tnote = {Number: 6\nPublisher: Multidisciplinary Digital Publishing Institute},\n\tkeywords = {\\textit{Eisenia} sp., Tea Bag Index, carbon/nitrogen ratio, olive litter, soil bacteria, soil chemico-physical properties, soil sustainable management},\n\tpages = {1216},\n}\n\n\n\n\n\n Earthworms and soil microorganisms contribute to soil health, quality, and fertility, but their importance in agricultural soils is often underestimated. This study aims at examining whether and to what extent the presence of earthworms (Eisenia sp.) affected the (a) soil bacterial community composition, (b) litter decomposition, and (c) plant growth (Brassica oleracea L., broccoli; Vicia faba L., faba bean). We performed a mesocosm experiment in which plants were grown outdoors for four months with or without earthworms. Soil bacterial community structure was evaluated by a 16S rRNA-based metabarcoding approach. Litter decomposition rates were determined by using the tea bag index (TBI) and litter bags (olive residues). Earthworm numbers almost doubled throughout the experimental period. Independently of the plant species, earthworm presence had a significant impact on the structure of soil bacterial community, in terms of enhanced α- and β-diversity (especially that of Proteobacteria, Bacteroidota, Myxococcota, and Verrucomicrobia) and increased 16S rRNA gene abundance (+89% in broccoli and +223% in faba bean). Microbial decomposition (TBI) was enhanced in the treatments with earthworms, and showed a significantly higher decomposition rate constant (kTBI) and a lower stabilization factor (STBI), whereas decomposition in the litter bags (dlitter) increased by about 6% in broccoli and 5% in faba bean. Earthworms significantly enhanced root growth (in terms of total length and fresh weight) of both plant species. Our results show the strong influence of earthworms and crop identity in shaping soil chemico-physical properties, soil bacterial community, litter decomposition and plant growth. These findings could be used for developing nature-based solutions that ensure the long-term biological sustainability of soil agro- and natural ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Differential Trends in Iron Concentrations of Boreal Streams Linked to Catchment Characteristics.\n \n \n \n \n\n\n \n Škerlep, M.; Nehzati, S.; Sponseller, R. A.; Persson, P.; Laudon, H.; and Kritzberg, E. S.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 37(3): e2022GB007484. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GB007484\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{skerlep_differential_2023,\n\ttitle = {Differential {Trends} in {Iron} {Concentrations} of {Boreal} {Streams} {Linked} to {Catchment} {Characteristics}},\n\tvolume = {37},\n\tcopyright = {© 2023. The Authors.},\n\tissn = {1944-9224},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GB007484},\n\tdoi = {10.1029/2022GB007484},\n\tabstract = {Increasing iron (Fe) concentrations have been reported for freshwaters across northern Europe over the last decades. This increase, together with elevated concentrations of dissolved organic carbon (DOC), leads to browning of freshwaters, which affects aquatic organisms, ecosystem functioning, biogeochemical cycles, and brings challenges to drinking water production. However, how such increasing trends in stream Fe concentrations reflect the contribution of different catchment sources remains poorly resolved. Here, we explored how catchment characteristics, that is, mires and coniferous soils, regulate spatial and temporal patterns of Fe in a boreal stream network. For this, we determined Fe speciation in riparian and mire soils, and studied temporal Fe dynamics in soil-water and stream-water over a span of 18 years. Positive Fe trends were found in the solution of the riparian soil, while no long-term trend was observed in the mire. These differences were reflected in stream-water, where three headwater streams dominated by coniferous cover also displayed positive Fe trends, whereas the mire dominated stream showed no trend. Surprisingly, the majority of higher order streams showed declining Fe trends, despite long-term increases in DOC. In addition, we found that an extreme drought event led to a prolonged release of Fe and DOC from the riparian soils, that could have long-term effects on stream Fe concentrations. Our results show that riparian forest soils can be major contributors to ongoing increases in freshwater Fe concentrations and that drought can further promote the release of Fe from organic soils.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Škerlep, M. and Nehzati, S. and Sponseller, R. A. and Persson, P. and Laudon, H. and Kritzberg, E. S.},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GB007484},\n\tkeywords = {browning, catchment, iron, mire, riparian zone, stream},\n\tpages = {e2022GB007484},\n}\n\n\n\n\n\n Increasing iron (Fe) concentrations have been reported for freshwaters across northern Europe over the last decades. This increase, together with elevated concentrations of dissolved organic carbon (DOC), leads to browning of freshwaters, which affects aquatic organisms, ecosystem functioning, biogeochemical cycles, and brings challenges to drinking water production. However, how such increasing trends in stream Fe concentrations reflect the contribution of different catchment sources remains poorly resolved. Here, we explored how catchment characteristics, that is, mires and coniferous soils, regulate spatial and temporal patterns of Fe in a boreal stream network. For this, we determined Fe speciation in riparian and mire soils, and studied temporal Fe dynamics in soil-water and stream-water over a span of 18 years. Positive Fe trends were found in the solution of the riparian soil, while no long-term trend was observed in the mire. These differences were reflected in stream-water, where three headwater streams dominated by coniferous cover also displayed positive Fe trends, whereas the mire dominated stream showed no trend. Surprisingly, the majority of higher order streams showed declining Fe trends, despite long-term increases in DOC. In addition, we found that an extreme drought event led to a prolonged release of Fe and DOC from the riparian soils, that could have long-term effects on stream Fe concentrations. Our results show that riparian forest soils can be major contributors to ongoing increases in freshwater Fe concentrations and that drought can further promote the release of Fe from organic soils.\n
\n\n\n\n \n\n \n \n \n \n \n \n As good as human experts in detecting plant roots in minirhizotron images but efficient and reproducible: the convolutional neural network “RootDetector”.\n \n \n \n \n\n\n \n Peters, B.; Blume-Werry, G.; Gillert, A.; Schwieger, S.; von Lukas, U. F.; and Kreyling, J.\n\n\n \n\n\n\n Scientific Reports, 13(1): 1399. January 2023.\n Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{peters_as_2023,\n\ttitle = {As good as human experts in detecting plant roots in minirhizotron images but efficient and reproducible: the convolutional neural network “{RootDetector}”},\n\tvolume = {13},\n\tcopyright = {2023 The Author(s)},\n\tissn = {2045-2322},\n\tshorttitle = {As good as human experts in detecting plant roots in minirhizotron images but efficient and reproducible},\n\turl = {https://www.nature.com/articles/s41598-023-28400-x},\n\tdoi = {10.1038/s41598-023-28400-x},\n\tabstract = {Plant roots influence many ecological and biogeochemical processes, such as carbon, water and nutrient cycling. Because of difficult accessibility, knowledge on plant root growth dynamics in field conditions, however, is fragmentary at best. Minirhizotrons, i.e. transparent tubes placed in the substrate into which specialized cameras or circular scanners are inserted, facilitate the capture of high-resolution images of root dynamics at the soil-tube interface with little to no disturbance after the initial installation. Their use, especially in field studies with multiple species and heterogeneous substrates, though, is limited by the amount of work that subsequent manual tracing of roots in the images requires. Furthermore, the reproducibility and objectivity of manual root detection is questionable. Here, we use a Convolutional Neural Network (CNN) for the automatic detection of roots in minirhizotron images and compare the performance of our RootDetector with human analysts with different levels of expertise. Our minirhizotron data come from various wetlands on organic soils, i.e. highly heterogeneous substrates consisting of dead plant material, often times mainly roots, in various degrees of decomposition. This may be seen as one of the most challenging soil types for root segmentation in minirhizotron images. RootDetector showed a high capability to correctly segment root pixels in minirhizotron images from field observations (F1 = 0.6044; r2 compared to a human expert = 0.99). Reproducibility among humans, however, depended strongly on expertise level, with novices showing drastic variation among individual analysts and annotating on average more than 13-times higher root length/cm2 per image compared to expert analysts. CNNs such as RootDetector provide a reliable and efficient method for the detection of roots and root length in minirhizotron images even from challenging field conditions. Analyses with RootDetector thus save resources, are reproducible and objective, and are as accurate as manual analyses performed by human experts.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Scientific Reports},\n\tauthor = {Peters, Bo and Blume-Werry, Gesche and Gillert, Alexander and Schwieger, Sarah and von Lukas, Uwe Freiherr and Kreyling, Juergen},\n\tmonth = jan,\n\tyear = {2023},\n\tnote = {Publisher: Nature Publishing Group},\n\tkeywords = {Ecosystem ecology, Imaging},\n\tpages = {1399},\n}\n\n\n\n\n\n Plant roots influence many ecological and biogeochemical processes, such as carbon, water and nutrient cycling. Because of difficult accessibility, knowledge on plant root growth dynamics in field conditions, however, is fragmentary at best. Minirhizotrons, i.e. transparent tubes placed in the substrate into which specialized cameras or circular scanners are inserted, facilitate the capture of high-resolution images of root dynamics at the soil-tube interface with little to no disturbance after the initial installation. Their use, especially in field studies with multiple species and heterogeneous substrates, though, is limited by the amount of work that subsequent manual tracing of roots in the images requires. Furthermore, the reproducibility and objectivity of manual root detection is questionable. Here, we use a Convolutional Neural Network (CNN) for the automatic detection of roots in minirhizotron images and compare the performance of our RootDetector with human analysts with different levels of expertise. Our minirhizotron data come from various wetlands on organic soils, i.e. highly heterogeneous substrates consisting of dead plant material, often times mainly roots, in various degrees of decomposition. This may be seen as one of the most challenging soil types for root segmentation in minirhizotron images. RootDetector showed a high capability to correctly segment root pixels in minirhizotron images from field observations (F1 = 0.6044; r2 compared to a human expert = 0.99). Reproducibility among humans, however, depended strongly on expertise level, with novices showing drastic variation among individual analysts and annotating on average more than 13-times higher root length/cm2 per image compared to expert analysts. CNNs such as RootDetector provide a reliable and efficient method for the detection of roots and root length in minirhizotron images even from challenging field conditions. Analyses with RootDetector thus save resources, are reproducible and objective, and are as accurate as manual analyses performed by human experts.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Effects of Water Column Dissolved Oxygen Concentrations on Lake Methane Emissions—Results From a Whole-Lake Oxygenation Experiment.\n \n \n \n \n\n\n \n Pajala, G.; Sawakuchi, H. O.; Rudberg, D.; Schenk, J.; Sieczko, A.; Gålfalk, M.; Seekell, D.; Sundgren, I.; Thanh Duc, N.; Karlsson, J.; and Bastviken, D.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 128(11): e2022JG007185. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007185\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{pajala_effects_2023,\n\ttitle = {The {Effects} of {Water} {Column} {Dissolved} {Oxygen} {Concentrations} on {Lake} {Methane} {Emissions}—{Results} {From} a {Whole}-{Lake} {Oxygenation} {Experiment}},\n\tvolume = {128},\n\tcopyright = {© 2023. The Authors.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JG007185},\n\tdoi = {10.1029/2022JG007185},\n\tabstract = {Lakes contribute 9\\%–19\\% of global methane (CH4) emissions to the atmosphere. Dissolved molecular oxygen (DO) in lakes can inhibit the production of CH4 and promote CH4 oxidation. DO is therefore often considered an important regulator of CH4 emissions from lakes. Presence or absence of DO in the water above the sediments can affect CH4 production and emissions by (a) influencing if methane production can be fueled by the most reactive organic matter in the top sediment layer or rely on deeper and less degradable organic matter, and (b) enabling CH4 accumulation in deep waters and potentially large emissions upon water column turnover. However, the relative importance of these two DO effects on CH4 fluxes is still unclear. We assessed CH4 fluxes from two connected lake basins in northern boreal Sweden where one was experimentally oxygenated. Results showed no clear difference in summer CH4 emissions attributable to water column DO concentrations. Large amounts of CH4 accumulated in the anoxic hypolimnion of the reference basin but little of this may have been emitted because of incomplete mixing, and effective methane oxidation of stored CH4 reaching oxic water layers. Accordingly, ≤24\\% of the stored CH4 was likely emitted in the experimental lake. Overall, our results suggest that hypolimnetic DO and water column CH4 storage might have a smaller impact on CH4 emissions in boreal forest lakes than previous estimates, yet potential fluxes associated with water column turnover events remain a significant uncertainty in lake CH4 emission estimates.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Pajala, Gustav and Sawakuchi, Henrique O. and Rudberg, David and Schenk, Jonathan and Sieczko, Anna and Gålfalk, Magnus and Seekell, David and Sundgren, Ingrid and Thanh Duc, Nguyen and Karlsson, Jan and Bastviken, David},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007185},\n\tkeywords = {dissolved oxygen, emissions, methane, methane oxidation, storage},\n\tpages = {e2022JG007185},\n}\n\n\n\n\n\n Lakes contribute 9%–19% of global methane (CH4) emissions to the atmosphere. Dissolved molecular oxygen (DO) in lakes can inhibit the production of CH4 and promote CH4 oxidation. DO is therefore often considered an important regulator of CH4 emissions from lakes. Presence or absence of DO in the water above the sediments can affect CH4 production and emissions by (a) influencing if methane production can be fueled by the most reactive organic matter in the top sediment layer or rely on deeper and less degradable organic matter, and (b) enabling CH4 accumulation in deep waters and potentially large emissions upon water column turnover. However, the relative importance of these two DO effects on CH4 fluxes is still unclear. We assessed CH4 fluxes from two connected lake basins in northern boreal Sweden where one was experimentally oxygenated. Results showed no clear difference in summer CH4 emissions attributable to water column DO concentrations. Large amounts of CH4 accumulated in the anoxic hypolimnion of the reference basin but little of this may have been emitted because of incomplete mixing, and effective methane oxidation of stored CH4 reaching oxic water layers. Accordingly, ≤24% of the stored CH4 was likely emitted in the experimental lake. Overall, our results suggest that hypolimnetic DO and water column CH4 storage might have a smaller impact on CH4 emissions in boreal forest lakes than previous estimates, yet potential fluxes associated with water column turnover events remain a significant uncertainty in lake CH4 emission estimates.\n
\n\n\n\n \n\n \n \n \n \n \n \n Concentration-Discharge Patterns Reveal Catchment Controls Over the Stoichiometry of Carbon and Nutrient Supply to Boreal Streams.\n \n \n \n \n\n\n \n Mosquera, V.; Laudon, H.; Blackburn, M.; Hasselquist, E. M.; and Sponseller, R. A.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 128(8): e2022JG007179. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007179\n\n\n\n
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\n\n\n@article{mosquera_concentration-discharge_2023,\n\ttitle = {Concentration-{Discharge} {Patterns} {Reveal} {Catchment} {Controls} {Over} the {Stoichiometry} of {Carbon} and {Nutrient} {Supply} to {Boreal} {Streams}},\n\tvolume = {128},\n\tcopyright = {© 2023. The Authors.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022JG007179},\n\tdoi = {10.1029/2022JG007179},\n\tabstract = {Carbon (C), nitrogen (N), and phosphorus (P) export from catchments is strongly regulated by interactions between hydrological flowpaths and their terrestrial use/storage. While concentration-discharge (c-Q) relationships have been widely used to understand this interplay for C, N, and P individually, how flow regulates the relative supply of these resources across spatial and temporal scales is not well documented. Here, we analyze c-Q relationships from 12 years of data to test how seasonal flow regulates the concentrations of inorganic N (Dissolved inorganic nitrogen [DIN]) and P (Dissolved inorganic phosphorus [DIP]), dissolved organic N (DON) and C (dissolved organic carbon [DOC]) and their respective ratios across 12 streams in a boreal landscape. We observed opposing c-Q relationships between organic and inorganic solutes. DOC and DON tended toward transport limitation with little year-to-year change, whereas ammonium (NH4) and DIP were increasingly source limited over time. These different c-Q relationships translated into large (up to three-fold) shifts in resource ratios (e.g., DOC:DIN) in response to changes in flow. Our results also highlight strong influences of catchment structure on c-Q patterns, regardless of solute, season, and longer-term directional changes. Here, the organic solute c-Q responses became less transport limited over time; while inorganic solute responses became less source limited with increasing mire/decreasing forest cover. Overall, differences in timing of catchment exports for C, N, and P, create dynamic variation in solute concentrations in streams with subsequent impacts on resource stoichiometry that is central to aquatic ecological processes.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2024-03-26},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Mosquera, Virginia and Laudon, Hjalmar and Blackburn, Meredith and Hasselquist, Eliza Maher and Sponseller, Ryan A.},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022JG007179},\n\tkeywords = {boreal catchments, concentration-discharge relationships, dissolved organic carbon, nitrogen, nutrient stoichiometry, phosphorus},\n\tpages = {e2022JG007179},\n}\n\n\n\n\n\n Carbon (C), nitrogen (N), and phosphorus (P) export from catchments is strongly regulated by interactions between hydrological flowpaths and their terrestrial use/storage. While concentration-discharge (c-Q) relationships have been widely used to understand this interplay for C, N, and P individually, how flow regulates the relative supply of these resources across spatial and temporal scales is not well documented. Here, we analyze c-Q relationships from 12 years of data to test how seasonal flow regulates the concentrations of inorganic N (Dissolved inorganic nitrogen [DIN]) and P (Dissolved inorganic phosphorus [DIP]), dissolved organic N (DON) and C (dissolved organic carbon [DOC]) and their respective ratios across 12 streams in a boreal landscape. We observed opposing c-Q relationships between organic and inorganic solutes. DOC and DON tended toward transport limitation with little year-to-year change, whereas ammonium (NH4) and DIP were increasingly source limited over time. These different c-Q relationships translated into large (up to three-fold) shifts in resource ratios (e.g., DOC:DIN) in response to changes in flow. Our results also highlight strong influences of catchment structure on c-Q patterns, regardless of solute, season, and longer-term directional changes. Here, the organic solute c-Q responses became less transport limited over time; while inorganic solute responses became less source limited with increasing mire/decreasing forest cover. Overall, differences in timing of catchment exports for C, N, and P, create dynamic variation in solute concentrations in streams with subsequent impacts on resource stoichiometry that is central to aquatic ecological processes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Complete chloroplast genomes of Cerastium alpinum, C. arcticum and C. nigrescens: genome structures, comparative and phylogenetic analysis.\n \n \n \n \n\n\n \n Milarska, S. E.; Androsiuk, P.; Paukszto, Ł.; Jastrzębski, J. P.; Maździarz, M.; Larson, K. W.; and Giełwanowska, I.\n\n\n \n\n\n\n Scientific Reports, 13(1): 18774. October 2023.\n Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{milarska_complete_2023,\n\ttitle = {Complete chloroplast genomes of {Cerastium} alpinum, {C}. arcticum and {C}. nigrescens: genome structures, comparative and phylogenetic analysis},\n\tvolume = {13},\n\tcopyright = {2023 The Author(s)},\n\tissn = {2045-2322},\n\tshorttitle = {Complete chloroplast genomes of {Cerastium} alpinum, {C}. arcticum and {C}. nigrescens},\n\turl = {https://www.nature.com/articles/s41598-023-46017-y},\n\tdoi = {10.1038/s41598-023-46017-y},\n\tabstract = {The genus Cerastium includes about 200 species that are mostly found in the temperate climates of the Northern Hemisphere. Here we report the complete chloroplast genomes of Cerastium alpinum, C. arcticum and C. nigrescens. The length of cp genomes ranged from 147,940 to 148,722 bp. Their quadripartite circular structure had the same gene organization and content, containing 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. Repeat sequences varied from 16 to 23 per species, with palindromic repeats being the most frequent. The number of identified SSRs ranged from 20 to 23 per species and they were mainly composed of mononucleotide repeats containing A/T units. Based on Ka/Ks ratio values, most genes were subjected to purifying selection. The newly sequenced chloroplast genomes were characterized by a high frequency of RNA editing, including both C to U and U to C conversion. The phylogenetic relationships within the genus Cerastium and family Caryophyllaceae were reconstructed based on the sequences of 71 protein-coding genes. The topology of the phylogenetic tree was consistent with the systematic position of the studied species. All representatives of the genus Cerastium were gathered in a single clade with C. glomeratum sharing the least similarity with the others.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Scientific Reports},\n\tauthor = {Milarska, Sylwia E. and Androsiuk, Piotr and Paukszto, Łukasz and Jastrzębski, Jan P. and Maździarz, Mateusz and Larson, Keith W. and Giełwanowska, Irena},\n\tmonth = oct,\n\tyear = {2023},\n\tnote = {Publisher: Nature Publishing Group},\n\tkeywords = {Genetics, Plant sciences},\n\tpages = {18774},\n}\n\n\n\n\n\n The genus Cerastium includes about 200 species that are mostly found in the temperate climates of the Northern Hemisphere. Here we report the complete chloroplast genomes of Cerastium alpinum, C. arcticum and C. nigrescens. The length of cp genomes ranged from 147,940 to 148,722 bp. Their quadripartite circular structure had the same gene organization and content, containing 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. Repeat sequences varied from 16 to 23 per species, with palindromic repeats being the most frequent. The number of identified SSRs ranged from 20 to 23 per species and they were mainly composed of mononucleotide repeats containing A/T units. Based on Ka/Ks ratio values, most genes were subjected to purifying selection. The newly sequenced chloroplast genomes were characterized by a high frequency of RNA editing, including both C to U and U to C conversion. The phylogenetic relationships within the genus Cerastium and family Caryophyllaceae were reconstructed based on the sequences of 71 protein-coding genes. The topology of the phylogenetic tree was consistent with the systematic position of the studied species. All representatives of the genus Cerastium were gathered in a single clade with C. glomeratum sharing the least similarity with the others.\n
\n\n\n\n \n\n \n \n \n \n \n \n Nutrients Alter Methane Production and Oxidation in a Thawing Permafrost Mire.\n \n \n \n \n\n\n \n Kashi, N. N.; Hobbie, E. A.; Varner, R. K.; Wymore, A. S.; Ernakovich, J. G.; and Giesler, R.\n\n\n \n\n\n\n Ecosystems, 26(2): 302–317. March 2023.\n \n\n\n\n
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\n\n\n@article{kashi_nutrients_2023,\n\ttitle = {Nutrients {Alter} {Methane} {Production} and {Oxidation} in a {Thawing} {Permafrost} {Mire}},\n\tvolume = {26},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-022-00758-5},\n\tdoi = {10.1007/s10021-022-00758-5},\n\tabstract = {Permafrost thaw releases nutrients and metals from previously frozen soils and these nutrients may affect important biogeochemical processes including methane (CH4) production and oxidation. Here we assessed how concentrations of nutrients, solutes, and metals varied across four plant communities undergoing permafrost thaw and if these geochemical characteristics affected rates of CH4 production and oxidation. We tested nutrient limitation in CH4 production and oxidation by experimentally adding nitrogen (N), phosphorus (P) and a permafrost leachate to peat across these four plant communities. The upper 20 cm of permafrost contained 715 ± 298 mg m−2 of extractable inorganic N and 20 ± 6 mg m−2 of resin-extractable phosphorus (Presin), for a N:P ratio of 36:1. These low amounts of Presin coincide with high acid-digestible aluminum (Al), iron (Fe), and P concentrations in the permafrost soil and suggest that P may accumulate via sorption and constrain easily available forms of P for plants and microbes. Permafrost leachate additions decreased potential CH4 production rates up to 80\\% and decreased CH4 oxidation rates by 66\\%, likely due to inhibitory effects of N in the permafrost. In contrast, organic and inorganic P additions increased CH4 oxidation rates up to 36\\% in the tall graminoid fen, a community where phosphate availability was low and CH4 production was high. Our results suggest that (1) inorganic N is available immediately from permafrost thaw, while (2) P availability is controlled by sorption properties, and (3) plant community, nutrient stoichiometry, and metal availability modulate how permafrost thaw affects CH4 production and oxidation.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Ecosystems},\n\tauthor = {Kashi, N. Niloufar and Hobbie, Erik A. and Varner, Ruth K. and Wymore, Adam S. and Ernakovich, Jessica G. and Giesler, Reiner},\n\tmonth = mar,\n\tyear = {2023},\n\tkeywords = {\\#nosource, iron, methane oxidation, methane production, nutrients, peatlands, permafrost, phosphorus sorption, resource stoichiometry},\n\tpages = {302--317},\n}\n\n\n\n\n\n Permafrost thaw releases nutrients and metals from previously frozen soils and these nutrients may affect important biogeochemical processes including methane (CH4) production and oxidation. Here we assessed how concentrations of nutrients, solutes, and metals varied across four plant communities undergoing permafrost thaw and if these geochemical characteristics affected rates of CH4 production and oxidation. We tested nutrient limitation in CH4 production and oxidation by experimentally adding nitrogen (N), phosphorus (P) and a permafrost leachate to peat across these four plant communities. The upper 20 cm of permafrost contained 715 ± 298 mg m−2 of extractable inorganic N and 20 ± 6 mg m−2 of resin-extractable phosphorus (Presin), for a N:P ratio of 36:1. These low amounts of Presin coincide with high acid-digestible aluminum (Al), iron (Fe), and P concentrations in the permafrost soil and suggest that P may accumulate via sorption and constrain easily available forms of P for plants and microbes. Permafrost leachate additions decreased potential CH4 production rates up to 80% and decreased CH4 oxidation rates by 66%, likely due to inhibitory effects of N in the permafrost. In contrast, organic and inorganic P additions increased CH4 oxidation rates up to 36% in the tall graminoid fen, a community where phosphate availability was low and CH4 production was high. Our results suggest that (1) inorganic N is available immediately from permafrost thaw, while (2) P availability is controlled by sorption properties, and (3) plant community, nutrient stoichiometry, and metal availability modulate how permafrost thaw affects CH4 production and oxidation.\n
\n\n\n\n \n\n \n \n \n \n \n \n Understory functional groups and fire history but not experimental warming drive tree seedling performance in unmanaged boreal forests.\n \n \n \n \n\n\n \n Jessen, M.; Krab, E. J.; Lett, S.; Nilsson, M.; Teuber, L.; Wardle, D. A.; and Dorrepaal, E.\n\n\n \n\n\n\n Frontiers in Forests and Global Change, 6: 1130532. May 2023.\n Publisher: Frontiers\n\n\n\n
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\n\n\n@article{jessen_understory_2023,\n\ttitle = {Understory functional groups and fire history but not experimental warming drive tree seedling performance in unmanaged boreal forests},\n\tvolume = {6},\n\tissn = {2624-893X},\n\turl = {https://www.frontiersin.org/articles/10.3389/ffgc.2023.1130532},\n\tdoi = {10.3389/ffgc.2023.1130532},\n\tabstract = {Survival and growth of tree seedlings are key processes of regeneration in forest ecosystems. However, little is known about how climate warming modulates seedling performance either directly or in interaction with understory vegetation and post-fire successional stages. We measured survival (over three years) and growth of seedlings of three tree species (Betula pubescens, Pinus sylvestris and Picea abies) in a full-factorial field experiment with passive warming and removal of two plant functional groups (feather moss and/or ericaceous shrubs) along a post-fire chronosequence in an unmanaged boreal forest. Warming had no effect on seedling survival over time or on relative biomass growth. Meanwhile, moss removal greatly increased seedling survival overall, while shrub removal cancelled this effect for B. pubescens seedlings. In addition, B. pubescens and P. sylvestris survival benefitted most from moss removal in old forests ({\\textgreater}260 years since last fire disturbance). In contrast to survival, seedling growth was promoted by shrub removal for two out of three species, i.e., P. sylvestris and P. abies, meaning that seedling survival and growth are governed by different understory functional groups affecting seedling performance through different mechanism and modes of action. Our findings highlight that understory vegetation and to a lesser extent post-fire successional stage are important drivers of seedling performance while the direct effect of climate warming is not. This suggests that tree regeneration in future forests may be more responsive to changes in understory vegetation or fire regime, e.g. indirectly caused by warming, than to direct or interactive effects of rising temperatures.},\n\tlanguage = {English},\n\turldate = {2024-03-26},\n\tjournal = {Frontiers in Forests and Global Change},\n\tauthor = {Jessen, Maria-Theresa and Krab, Eveline J. and Lett, Signe and Nilsson, Marie-Charlotte and Teuber, Laurenz and Wardle, David A. and Dorrepaal, Ellen},\n\tmonth = may,\n\tyear = {2023},\n\tnote = {Publisher: Frontiers},\n\tkeywords = {Climate Change, Forest regneration, Shrubs, Survival, forest fire, moss, plant functional group removal},\n\tpages = {1130532},\n}\n\n\n\n\n\n Survival and growth of tree seedlings are key processes of regeneration in forest ecosystems. However, little is known about how climate warming modulates seedling performance either directly or in interaction with understory vegetation and post-fire successional stages. We measured survival (over three years) and growth of seedlings of three tree species (Betula pubescens, Pinus sylvestris and Picea abies) in a full-factorial field experiment with passive warming and removal of two plant functional groups (feather moss and/or ericaceous shrubs) along a post-fire chronosequence in an unmanaged boreal forest. Warming had no effect on seedling survival over time or on relative biomass growth. Meanwhile, moss removal greatly increased seedling survival overall, while shrub removal cancelled this effect for B. pubescens seedlings. In addition, B. pubescens and P. sylvestris survival benefitted most from moss removal in old forests (\\textgreater260 years since last fire disturbance). In contrast to survival, seedling growth was promoted by shrub removal for two out of three species, i.e., P. sylvestris and P. abies, meaning that seedling survival and growth are governed by different understory functional groups affecting seedling performance through different mechanism and modes of action. Our findings highlight that understory vegetation and to a lesser extent post-fire successional stage are important drivers of seedling performance while the direct effect of climate warming is not. This suggests that tree regeneration in future forests may be more responsive to changes in understory vegetation or fire regime, e.g. indirectly caused by warming, than to direct or interactive effects of rising temperatures.\n
\n\n\n\n \n\n \n \n \n \n \n \n The legacy of ecological imperialism in the Scandes: Earthworms and their implications for Arctic research.\n \n \n \n \n\n\n \n Jerand, P.; Klaminder, J.; and Linderholm, J.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 55(1): 2274650. December 2023.\n Publisher: Taylor & Francis _eprint: https://doi.org/10.1080/15230430.2023.2274650\n\n\n\n
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\n\n\n@article{jerand_legacy_2023,\n\ttitle = {The legacy of ecological imperialism in the {Scandes}: {Earthworms} and their implications for {Arctic} research},\n\tvolume = {55},\n\tissn = {1523-0430},\n\tshorttitle = {The legacy of ecological imperialism in the {Scandes}},\n\turl = {https://doi.org/10.1080/15230430.2023.2274650},\n\tdoi = {10.1080/15230430.2023.2274650},\n\tabstract = {In the nineteenth century, numerous settlements were established in the alpine region of Fennoscandia (the Scandes), an area that later became a major international scene for Arctic research. Here we raise awareness of this era and show that earthworm-driven bioturbation in “pristine” soils around contemporary Arctic research infrastructure is caused by soil fauna left behind during early land use. We use soil preserved under an alpine settlement to highlight that soils were not bioturbated when the first house was built at a site where bioturbation is now widespread. A review of archived material with unique site-specific chronology constrained the onset of bioturbation to the post-1871 era. Our results suggest that small-scale land use introduced earthworms that now thrive far beyond the realms of former cultivated fields. The legacy of soil fauna from this example of “ecological imperialism” still lingers and should be considered when studying soils of the Scandes.},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Jerand, Philip and Klaminder, Jonatan and Linderholm, Johan},\n\tmonth = dec,\n\tyear = {2023},\n\tnote = {Publisher: Taylor \\& Francis\n\\_eprint: https://doi.org/10.1080/15230430.2023.2274650},\n\tkeywords = {Archaeology, bioturbation, historical sources, phosphate analysis, soil classification},\n\tpages = {2274650},\n}\n\n\n\n\n\n In the nineteenth century, numerous settlements were established in the alpine region of Fennoscandia (the Scandes), an area that later became a major international scene for Arctic research. Here we raise awareness of this era and show that earthworm-driven bioturbation in “pristine” soils around contemporary Arctic research infrastructure is caused by soil fauna left behind during early land use. We use soil preserved under an alpine settlement to highlight that soils were not bioturbated when the first house was built at a site where bioturbation is now widespread. A review of archived material with unique site-specific chronology constrained the onset of bioturbation to the post-1871 era. Our results suggest that small-scale land use introduced earthworms that now thrive far beyond the realms of former cultivated fields. The legacy of soil fauna from this example of “ecological imperialism” still lingers and should be considered when studying soils of the Scandes.\n
\n\n\n\n \n\n \n \n \n \n \n \n The drivers of dark diversity in the Scandinavian mountains are metric-dependent.\n \n \n \n \n\n\n \n Hostens, L.; Van Meerbeek, K.; Wiegmans, D.; Larson, K.; Lenoir, J.; Clavel, J.; Wedegärtner, R.; Pirée, A.; Nijs, I.; and Lembrechts, J. J.\n\n\n \n\n\n\n Journal of Vegetation Science, 34(6): e13212. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.13212\n\n\n\n
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\n\n\n@article{hostens_drivers_2023,\n\ttitle = {The drivers of dark diversity in the {Scandinavian} mountains are metric-dependent},\n\tvolume = {34},\n\tcopyright = {© 2023 International Association for Vegetation Science.},\n\tissn = {1654-1103},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.13212},\n\tdoi = {10.1111/jvs.13212},\n\tabstract = {Question Dark diversity refers to the set of species that are not observed in an area but could potentially occur based on suitable local environmental conditions. In this paper, we applied both niche-based and co-occurrence-based methods to estimate the dark diversity of vascular plant species in the subarctic mountains. We then aimed to unravel the drivers explaining (a) why some locations were missing relatively more suitable species than others, and (b) why certain plant species were more often absent from suitable locations than others. Location The Scandinavian mountains around Abisko, northern Sweden. Methods We calculated the dark diversity in 107 plots spread out across four mountain trails using four different methods: two co-occurrence-based (Beals’ index and the hypergeometric method) and two niche-based (the climatic niche model and climatic niche model followed by species-specific threshold). We then applied multiple Generalized Linear Mixed-Effects Models and General Linear Models to determine which habitat characteristics and species traits contributed the most to dark diversity. Results The study showed a notable divergence in the predicted drivers of dark diversity depending on the method used. Nevertheless, we can conclude that plot-level dark diversity was generally 17\\% higher in areas at low elevations and 31\\% higher in areas with a low species richness. Conclusion Our findings call for caution when interpreting statistical findings of dark-diversity estimates. Even so, all analyses point toward an important role for natural processes such as competitive dominance as the main driver of the spatial patterns found in dark diversity in the northern Scandes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-26},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Hostens, Lore and Van Meerbeek, Koenraad and Wiegmans, Dymphna and Larson, Keith and Lenoir, Jonathan and Clavel, Jan and Wedegärtner, Ronja and Pirée, Amber and Nijs, Ivan and Lembrechts, Jonas J.},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.13212},\n\tkeywords = {Beals’ index, co-occurrence model, habitat characteristics, method comparison, niche model, plant diversity, plant ecology, plant traits, regional species pool},\n\tpages = {e13212},\n}\n\n\n\n\n\n Question Dark diversity refers to the set of species that are not observed in an area but could potentially occur based on suitable local environmental conditions. In this paper, we applied both niche-based and co-occurrence-based methods to estimate the dark diversity of vascular plant species in the subarctic mountains. We then aimed to unravel the drivers explaining (a) why some locations were missing relatively more suitable species than others, and (b) why certain plant species were more often absent from suitable locations than others. Location The Scandinavian mountains around Abisko, northern Sweden. Methods We calculated the dark diversity in 107 plots spread out across four mountain trails using four different methods: two co-occurrence-based (Beals’ index and the hypergeometric method) and two niche-based (the climatic niche model and climatic niche model followed by species-specific threshold). We then applied multiple Generalized Linear Mixed-Effects Models and General Linear Models to determine which habitat characteristics and species traits contributed the most to dark diversity. Results The study showed a notable divergence in the predicted drivers of dark diversity depending on the method used. Nevertheless, we can conclude that plot-level dark diversity was generally 17% higher in areas at low elevations and 31% higher in areas with a low species richness. Conclusion Our findings call for caution when interpreting statistical findings of dark-diversity estimates. Even so, all analyses point toward an important role for natural processes such as competitive dominance as the main driver of the spatial patterns found in dark diversity in the northern Scandes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Landscape constraints on mire lateral expansion.\n \n \n \n \n\n\n \n Ehnvall, B.; Ratcliffe, J. L.; Bohlin, E.; Nilsson, M. B.; Öquist, M. G.; Sponseller, R. A.; and Grabs, T.\n\n\n \n\n\n\n Quaternary Science Reviews, 302: 107961. February 2023.\n \n\n\n\n
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\n\n\n@article{ehnvall_landscape_2023,\n\ttitle = {Landscape constraints on mire lateral expansion},\n\tvolume = {302},\n\tissn = {0277-3791},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0277379123000094},\n\tdoi = {10.1016/j.quascirev.2023.107961},\n\tabstract = {Little is known about the long-term expansion of mire ecosystems, despite their importance in the global carbon and hydrogeochemical cycles. It has been firmly established that mires do not expand linearly over time. Despite this, mires are often assumed to have expanded at a constant rate after initiation simply for lack of a better understanding. There has not yet been a serious attempt to determine the rate and drivers of mire expansion at the regional, or larger spatial scales. Here we make use of a natural chronosequence, spanning the Holocene, which is provided by the retreating coastline of Northern Sweden. By studying an isostatic rebound area we can infer mire expansion dynamics by looking at the portion of the landscape where mires become progressively scarce as the land becomes younger. Our results confirms that mires expanded non-linearly across the landscape and that their expansion is related to the availability of suitably wet areas, which, in our case, depends primarily on the hydro-edaphic properties of the landscape. Importantly, we found that mires occupied the wettest locations in the landscape within only one to two thousand years, while it took mires three to four thousand years to expand into slightly drier areas. Our results imply that the lateral expansion of mires, and thus peat accumulation is a non-linear process, occurring at different rates depending, above all else, on the wetness of the landscape.},\n\turldate = {2024-03-26},\n\tjournal = {Quaternary Science Reviews},\n\tauthor = {Ehnvall, Betty and Ratcliffe, Joshua L. and Bohlin, Elisabet and Nilsson, Mats B. and Öquist, Mats G. and Sponseller, Ryan A. and Grabs, Thomas},\n\tmonth = feb,\n\tyear = {2023},\n\tkeywords = {Boreal zone, Chronosequence, Holocene, Landscape ecology, Landscape wetness, Mire available areas, Mire lateral expansion, Non-linear, Peat accumulation},\n\tpages = {107961},\n}\n\n\n\n\n\n Little is known about the long-term expansion of mire ecosystems, despite their importance in the global carbon and hydrogeochemical cycles. It has been firmly established that mires do not expand linearly over time. Despite this, mires are often assumed to have expanded at a constant rate after initiation simply for lack of a better understanding. There has not yet been a serious attempt to determine the rate and drivers of mire expansion at the regional, or larger spatial scales. Here we make use of a natural chronosequence, spanning the Holocene, which is provided by the retreating coastline of Northern Sweden. By studying an isostatic rebound area we can infer mire expansion dynamics by looking at the portion of the landscape where mires become progressively scarce as the land becomes younger. Our results confirms that mires expanded non-linearly across the landscape and that their expansion is related to the availability of suitably wet areas, which, in our case, depends primarily on the hydro-edaphic properties of the landscape. Importantly, we found that mires occupied the wettest locations in the landscape within only one to two thousand years, while it took mires three to four thousand years to expand into slightly drier areas. Our results imply that the lateral expansion of mires, and thus peat accumulation is a non-linear process, occurring at different rates depending, above all else, on the wetness of the landscape.\n
\n\n\n\n \n\n \n \n \n \n \n \n Arctic rooting depth distribution influences modelled carbon emissions but cannot be inferred from aboveground vegetation type.\n \n \n \n \n\n\n \n Blume-Werry, G.; Dorrepaal, E.; Keuper, F.; Kummu, M.; Wild, B.; and Weedon, J. T.\n\n\n \n\n\n\n New Phytologist, 240(2): 502–514. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/nph.18998\n\n\n\n
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\n\n\n@article{blume-werry_arctic_2023,\n\ttitle = {Arctic rooting depth distribution influences modelled carbon emissions but cannot be inferred from aboveground vegetation type},\n\tvolume = {240},\n\tcopyright = {© 2023 The Authors New Phytologist © 2023 New Phytologist Foundation},\n\tissn = {1469-8137},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.18998},\n\tdoi = {10.1111/nph.18998},\n\tabstract = {The distribution of roots throughout the soil drives depth-dependent plant–soil interactions and ecosystem processes, particularly in arctic tundra where plant biomass, is predominantly belowground. Vegetation is usually classified from aboveground, but it is unclear whether such classifications are suitable to estimate belowground attributes and their consequences, such as rooting depth distribution and its influence on carbon cycling. We performed a meta-analysis of 55 published arctic rooting depth profiles, testing for differences both between distributions based on aboveground vegetation types (Graminoid, Wetland, Erect-shrub, and Prostrate-shrub tundra) and between ‘Root Profile Types’ for which we defined three representative and contrasting clusters. We further analyzed potential impacts of these different rooting depth distributions on rhizosphere priming-induced carbon losses from tundra soils. Rooting depth distribution hardly differed between aboveground vegetation types but varied between Root Profile Types. Accordingly, modelled priming-induced carbon emissions were similar between aboveground vegetation types when they were applied to the entire tundra, but ranged from 7.2 to 17.6 Pg C cumulative emissions until 2100 between individual Root Profile Types. Variations in rooting depth distribution are important for the circumpolar tundra carbon-climate feedback but can currently not be inferred adequately from aboveground vegetation type classifications.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {New Phytologist},\n\tauthor = {Blume-Werry, Gesche and Dorrepaal, Ellen and Keuper, Frida and Kummu, Matti and Wild, Birgit and Weedon, James T.},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/nph.18998},\n\tkeywords = {\\#nosource, arctic tundra, permafrost, plant–soil interactions, rhizosphere priming effect, root biomass, root vertical distribution strategies, rooting depth},\n\tpages = {502--514},\n}\n\n\n\n\n\n The distribution of roots throughout the soil drives depth-dependent plant–soil interactions and ecosystem processes, particularly in arctic tundra where plant biomass, is predominantly belowground. Vegetation is usually classified from aboveground, but it is unclear whether such classifications are suitable to estimate belowground attributes and their consequences, such as rooting depth distribution and its influence on carbon cycling. We performed a meta-analysis of 55 published arctic rooting depth profiles, testing for differences both between distributions based on aboveground vegetation types (Graminoid, Wetland, Erect-shrub, and Prostrate-shrub tundra) and between ‘Root Profile Types’ for which we defined three representative and contrasting clusters. We further analyzed potential impacts of these different rooting depth distributions on rhizosphere priming-induced carbon losses from tundra soils. Rooting depth distribution hardly differed between aboveground vegetation types but varied between Root Profile Types. Accordingly, modelled priming-induced carbon emissions were similar between aboveground vegetation types when they were applied to the entire tundra, but ranged from 7.2 to 17.6 Pg C cumulative emissions until 2100 between individual Root Profile Types. Variations in rooting depth distribution are important for the circumpolar tundra carbon-climate feedback but can currently not be inferred adequately from aboveground vegetation type classifications.\n
\n\n\n\n \n\n \n \n \n \n \n \n Optical and radar Earth observation data for upscaling methane emissions linked to permafrost degradation in sub-Arctic peatlands in northern Sweden.\n \n \n \n \n\n\n \n Sjögersten, S.; Ledger, M.; Siewert, M. B.; De La Barreda-Bautista, B.; Sowter, A.; Gee, D.; Foody, G.; and Boyd, D. S.\n\n\n \n\n\n\n Biogeosciences, 20(20): 4221–4239. 2023.\n Publisher: Copernicus Publications\n\n\n\n
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\n\n\n@article{sjogersten_optical_2023,\n\ttitle = {Optical and radar {Earth} observation data for upscaling methane emissions linked to permafrost degradation in sub-{Arctic} peatlands in northern {Sweden}},\n\tvolume = {20},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-218475},\n\tdoi = {10.5194/bg-20-4221-2023},\n\tabstract = {Permafrost thaw in Arctic regions is increasing methane (CH4) emissions into the atmosphere, but quantification of such emissions is difficult given the large and remote areas impacted. Hence, Eart ...},\n\tlanguage = {eng},\n\tnumber = {20},\n\turldate = {2024-03-26},\n\tjournal = {Biogeosciences},\n\tauthor = {Sjögersten, Sofie and Ledger, Martha and Siewert, Matthias B. and De La Barreda-Bautista, Betsabé and Sowter, Andrew and Gee, David and Foody, Giles and Boyd, Doreen S.},\n\tyear = {2023},\n\tnote = {Publisher: Copernicus Publications},\n\tpages = {4221--4239},\n}\n\n\n\n\n\n Permafrost thaw in Arctic regions is increasing methane (CH4) emissions into the atmosphere, but quantification of such emissions is difficult given the large and remote areas impacted. Hence, Eart ...\n
\n\n\n\n \n\n \n \n \n \n \n \n As a permafrost ecosystem warms, plant community traits become more acquisitive.\n \n \n \n \n\n\n \n Spitzer, C. M.; and Blume-Werry, G.\n\n\n \n\n\n\n New Phytologist, 240(5): 1712–1713. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{spitzer_as_2023,\n\ttitle = {As a permafrost ecosystem warms, plant community traits become more acquisitive},\n\tvolume = {240},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-215375},\n\tdoi = {10.1111/nph.19286},\n\tabstract = {As a permafrost ecosystem warms, plant community traits become more acquisitive},\n\tlanguage = {eng},\n\tnumber = {5},\n\turldate = {2024-03-26},\n\tjournal = {New Phytologist},\n\tauthor = {Spitzer, Clydecia M. and Blume-Werry, Gesche},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {1712--1713},\n}\n\n\n\n\n\n As a permafrost ecosystem warms, plant community traits become more acquisitive\n
\n\n\n\n \n\n \n \n \n \n \n \n Warming nondormant tree roots advances aboveground spring phenology in temperate trees.\n \n \n \n \n\n\n \n Malyshev, A. V.; Blume-Werry, G.; Spiller, O.; Smiljanić, M.; Weigel, R.; Kolb, A.; Nze, B. Y.; Märker, F.; Sommer, F. C. J.; Kinley, K.; Ziegler, J.; Pasang, P.; Mahara, R.; Joshi, S.; Heinsohn, V.; and Kreyling, J.\n\n\n \n\n\n\n New Phytologist, 240(6): 2276–2287. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{malyshev_warming_2023,\n\ttitle = {Warming nondormant tree roots advances aboveground spring phenology in temperate trees},\n\tvolume = {240},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-216213},\n\tdoi = {10.1111/nph.19304},\n\tabstract = {Climate warming advances the onset of tree growth in spring, but above- and belowground phenology are not always synchronized. These differences in growth responses may result from differences in r ...},\n\tlanguage = {eng},\n\tnumber = {6},\n\turldate = {2024-03-26},\n\tjournal = {New Phytologist},\n\tauthor = {Malyshev, Andrey V. and Blume-Werry, Gesche and Spiller, Ophelia and Smiljanić, Marko and Weigel, Robert and Kolb, Alexander and Nze, Byron Ye and Märker, Frederik and Sommer, Freymuth Carl-Fried Johannes and Kinley, Kinley and Ziegler, Jan and Pasang, Pasang and Mahara, Robert and Joshi, Silviya and Heinsohn, Vincent and Kreyling, Juergen},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {2276--2287},\n}\n\n\n\n\n\n Climate warming advances the onset of tree growth in spring, but above- and belowground phenology are not always synchronized. These differences in growth responses may result from differences in r ...\n
\n\n\n\n \n\n \n \n \n \n \n \n How do leaf functional traits and age influence the maximum rooting depth of trees?.\n \n \n \n \n\n\n \n Makoto, K.; Kitagawa, R.; and Blume-Werry, G.\n\n\n \n\n\n\n European Journal of Forest Research, 142(5): 1197–1206. 2023.\n Publisher: Springer Science+Business Media B.V.\n\n\n\n
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\n\n\n@article{makoto_how_2023,\n\ttitle = {How do leaf functional traits and age influence the maximum rooting depth of trees?},\n\tvolume = {142},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-210225},\n\tdoi = {10.1007/s10342-023-01585-6},\n\tabstract = {Maximum rooting depth is a key functional trait to increase the fitness of trees and also influences terrestrial ecosystem processes. Despite its importance, the drivers of the interspecific variat ...},\n\tlanguage = {eng},\n\tnumber = {5},\n\turldate = {2024-03-26},\n\tjournal = {European Journal of Forest Research},\n\tauthor = {Makoto, Kobayashi and Kitagawa, Ryo and Blume-Werry, Gesche},\n\tyear = {2023},\n\tnote = {Publisher: Springer Science+Business Media B.V.},\n\tpages = {1197--1206},\n}\n\n\n\n\n\n Maximum rooting depth is a key functional trait to increase the fitness of trees and also influences terrestrial ecosystem processes. Despite its importance, the drivers of the interspecific variat ...\n
\n\n\n\n \n\n \n \n \n \n \n \n A review of open top chamber (OTC) performance across the ITEX Network.\n \n \n \n \n\n\n \n Hollister, R. D.; Elphinstone, C.; Henry, G. H. R.; Bjorkman, A. D.; Klanderud, K.; Björk, R. G.; Björkman, M. P.; Bokhorst, S.; Carbognani, M.; Cooper, E. J.; Dorrepaal, E.; Elmendorf, S. C.; Fetcher, N.; Gallois, E. C.; Guoðmundsson, J.; Healey, N. C.; Jónsdóttir, I. S.; Klarenberg, I. J.; Oberbauer, S. F.; Macek, P.; May, J. L.; Mereghetti, A.; Molau, U.; Petraglia, A.; Rinnan, R.; Rixen, C.; and Wookey, P. A.\n\n\n \n\n\n\n Arctic Science, 9(2): 331–344. 2023.\n Publisher: Canadian Science Publishing\n\n\n\n
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\n\n\n@article{hollister_review_2023,\n\ttitle = {A review of open top chamber ({OTC}) performance across the {ITEX} {Network}},\n\tvolume = {9},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-212056},\n\tdoi = {10.1139/as-2022-0030},\n\tabstract = {Open top chambers (OTCs) were adopted as the recommended warmingmechanism by the International Tundra Experiment network in the early 1990s. Since then, OTCs have been deployed across the globe. Hu ...},\n\tlanguage = {eng},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Arctic Science},\n\tauthor = {Hollister, Robert D. and Elphinstone, Cassandra and Henry, Greg H. R. and Bjorkman, Anne D. and Klanderud, Kari and Björk, Robert G. and Björkman, Mats P. and Bokhorst, Stef and Carbognani, Michele and Cooper, Elisabeth J. and Dorrepaal, Ellen and Elmendorf, Sarah C. and Fetcher, Ned and Gallois, Elise C. and Guoðmundsson, Jón and Healey, Nathan C. and Jónsdóttir, Ingibjörg Svala and Klarenberg, Ingeborg J. and Oberbauer, Steven F. and Macek, Petr and May, Jeremy L. and Mereghetti, Alessandro and Molau, Ulf and Petraglia, Alessandro and Rinnan, Riikka and Rixen, Christian and Wookey, Philip A.},\n\tyear = {2023},\n\tnote = {Publisher: Canadian Science Publishing},\n\tpages = {331--344},\n}\n\n\n\n\n\n Open top chambers (OTCs) were adopted as the recommended warmingmechanism by the International Tundra Experiment network in the early 1990s. Since then, OTCs have been deployed across the globe. Hu ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Impacts of reindeer on soil carbon storage in the seasonally frozen ground of northern Finland : a pilot study.\n \n \n \n \n\n\n \n Windirsch, T.; Forbes, B. C.; Grosse, G.; Wolter, J.; Stark, S.; Treat, C.; Ulrich, M.; Fuchs, M.; Olofsson, J.; Kumpula, T.; Macias-Fauria, M.; and Strauss, J.\n\n\n \n\n\n\n Boreal environment research, 28(1-6): 207–226. 2023.\n Publisher: Finish Environment Institute\n\n\n\n
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\n\n\n@article{windirsch_impacts_2023,\n\ttitle = {Impacts of reindeer on soil carbon storage in the seasonally frozen ground of northern {Finland} : a pilot study},\n\tvolume = {28},\n\tshorttitle = {Impacts of reindeer on soil carbon storage in the seasonally frozen ground of northern {Finland}},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-215354},\n\tabstract = {To test the effect of reindeer husbandry on soil carbon storage of seasonally frozen ground, we analysed soil and vegetation properties in peatlands and mixed pine and mountain birch forests. We an ...},\n\tlanguage = {eng},\n\tnumber = {1-6},\n\turldate = {2024-03-26},\n\tjournal = {Boreal environment research},\n\tauthor = {Windirsch, Torben and Forbes, Bruce C. and Grosse, Guido and Wolter, Juliane and Stark, Sari and Treat, Claire and Ulrich, Mathias and Fuchs, Matthias and Olofsson, Johan and Kumpula, Timo and Macias-Fauria, Marc and Strauss, Jens},\n\tyear = {2023},\n\tnote = {Publisher: Finish Environment Institute},\n\tkeywords = {⛔ No DOI found},\n\tpages = {207--226},\n}\n\n\n\n\n\n To test the effect of reindeer husbandry on soil carbon storage of seasonally frozen ground, we analysed soil and vegetation properties in peatlands and mixed pine and mountain birch forests. We an ...\n
\n\n\n\n \n\n \n \n \n \n \n \n GRiMeDB : the global river methane database of concentrations and fluxes.\n \n \n \n \n\n\n \n Stanley, E. H.; Loken, L. C.; Casson, N. J.; Oliver, S. K.; Sponseller, R. A.; Wallin, M. B.; Zhang, L.; and Rocher-Ros, G.\n\n\n \n\n\n\n Earth System Science Data, 15(7): 2879–2926. 2023.\n Publisher: Copernicus Publications\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n\n\n\n
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\n\n\n@article{stanley_grimedb_2023,\n\ttitle = {{GRiMeDB} : the global river methane database of concentrations and fluxes},\n\tvolume = {15},\n\tshorttitle = {{GRiMeDB}},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-215374},\n\tdoi = {10.5194/essd-15-2879-2023},\n\tabstract = {Despite their small spatial extent, fluvial ecosystems play a significant role in processing and transporting carbon in aquatic networks, which results in substantial emission of methane (CH4) into ...},\n\tlanguage = {eng},\n\tnumber = {7},\n\turldate = {2024-03-26},\n\tjournal = {Earth System Science Data},\n\tauthor = {Stanley, Emily H. and Loken, Luke C. and Casson, Nora J. and Oliver, Samantha K. and Sponseller, Ryan A. and Wallin, Marcus B. and Zhang, Liwei and Rocher-Ros, Gerard},\n\tyear = {2023},\n\tnote = {Publisher: Copernicus Publications},\n\tpages = {2879--2926},\n}\n\n\n\n\n\n Despite their small spatial extent, fluvial ecosystems play a significant role in processing and transporting carbon in aquatic networks, which results in substantial emission of methane (CH4) into ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Global methane emissions from rivers and streams.\n \n \n \n \n\n\n \n Rocher-Ros, G.; Stanley, E. H.; Loken, L. C.; Casson, N. J.; Raymond, P. A.; Liu, S.; Amatulli, G.; and Sponseller, R. A.\n\n\n \n\n\n\n Nature, 621(7979): 530–535. 2023.\n Publisher: Springer Nature\n\n\n\n
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\n\n\n@article{rocher-ros_global_2023,\n\ttitle = {Global methane emissions from rivers and streams},\n\tvolume = {621},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-213705},\n\tdoi = {10.1038/s41586-023-06344-6},\n\tabstract = {Methane (CH4) is a potent greenhouse gas and its concentrations have tripled in the atmosphere since the industrial revolution. There is evidence that global warming has increased CH4 emissions fro ...},\n\tlanguage = {eng},\n\tnumber = {7979},\n\turldate = {2024-03-26},\n\tjournal = {Nature},\n\tauthor = {Rocher-Ros, Gerard and Stanley, Emily H. and Loken, Luke C. and Casson, Nora J. and Raymond, Peter A. and Liu, Shaoda and Amatulli, Giuseppe and Sponseller, Ryan A.},\n\tyear = {2023},\n\tnote = {Publisher: Springer Nature},\n\tpages = {530--535},\n}\n\n\n\n\n\n Methane (CH4) is a potent greenhouse gas and its concentrations have tripled in the atmosphere since the industrial revolution. There is evidence that global warming has increased CH4 emissions fro ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-term changes in dissolved inorganic carbon across boreal streams caused by altered hydrology.\n \n \n \n \n\n\n \n Rehn, L.; Sponseller, R. A.; Laudon, H.; and Wallin, M. B.\n\n\n \n\n\n\n Limnology and Oceanography, 68(2): 409–423. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{rehn_long-term_2023,\n\ttitle = {Long-term changes in dissolved inorganic carbon across boreal streams caused by altered hydrology},\n\tvolume = {68},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-201749},\n\tdoi = {10.1002/lno.12282},\n\tabstract = {A major challenge for predicting future landscape carbon (C) balances is to understand how environmental changes affect the transfer of C from soils to surface waters. Here, we evaluated 14 yr (200 ...},\n\tlanguage = {eng},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Rehn, Lukas and Sponseller, Ryan A. and Laudon, Hjalmar and Wallin, Marcus B.},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {409--423},\n}\n\n\n\n\n\n A major challenge for predicting future landscape carbon (C) balances is to understand how environmental changes affect the transfer of C from soils to surface waters. Here, we evaluated 14 yr (200 ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Cascading, interactive, and indirect effects of climate change on aquatic communities, habitats, and ecosystems.\n \n \n \n \n\n\n \n Menden-Deuer, S.; Mullarney, J. C.; Boersma, M.; Grossart, H.; Sponseller, R. A.; and Woodin, S. A.\n\n\n \n\n\n\n Limnology and Oceanography, 68(S1): S1–S7. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{menden-deuer_cascading_2023,\n\ttitle = {Cascading, interactive, and indirect effects of climate change on aquatic communities, habitats, and ecosystems},\n\tvolume = {68},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-212501},\n\tdoi = {10.1002/lno.12384},\n\tabstract = {Climate-change is rapidly and intensively altering aquatic communities and habitats. While previous work has focused on direct effects of potential drivers, indirect and interactive effects on orga ...},\n\tlanguage = {eng},\n\tnumber = {S1},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Menden-Deuer, Susanne and Mullarney, Julia C. and Boersma, Maarten and Grossart, Hans-Peter and Sponseller, Ryan A. and Woodin, Sarah Ann},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {S1--S7},\n}\n\n\n\n\n\n Climate-change is rapidly and intensively altering aquatic communities and habitats. While previous work has focused on direct effects of potential drivers, indirect and interactive effects on orga ...\n
\n\n\n\n \n\n \n \n \n \n \n \n A long-established invasive species alters the functioning of benthic biofilms in lakes.\n \n \n \n \n\n\n \n McKie, B. G.; Tattersdill, K.; Ecke, F.; Frainer, A.; and Sponseller, R. A.\n\n\n \n\n\n\n Freshwater Biology, 68(12): 2068–2083. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{mckie_long-established_2023,\n\ttitle = {A long-established invasive species alters the functioning of benthic biofilms in lakes},\n\tvolume = {68},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-214759},\n\tdoi = {10.1111/fwb.14175},\n\tabstract = {Invasive species often transform environmental conditions, exclude native species and alter ecosystem functioning, including key ecosystem processes underpinning nutrient and energy cycles. However ...},\n\tlanguage = {eng},\n\tnumber = {12},\n\turldate = {2024-03-26},\n\tjournal = {Freshwater Biology},\n\tauthor = {McKie, Brendan G. and Tattersdill, Kristina and Ecke, Frauke and Frainer, André and Sponseller, Ryan A.},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {2068--2083},\n}\n\n\n\n\n\n Invasive species often transform environmental conditions, exclude native species and alter ecosystem functioning, including key ecosystem processes underpinning nutrient and energy cycles. However ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Groundwater-stream connections shape the spatial pattern and rates of aquatic metabolism.\n \n \n \n \n\n\n \n Lupon, A.; Gómez-Gener, L.; Fork, M. L.; Laudon, H.; Martí, E.; Lidberg, W.; and Sponseller, R. A.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 8(2): 350–358. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{lupon_groundwater-stream_2023,\n\ttitle = {Groundwater-stream connections shape the spatial pattern and rates of aquatic metabolism},\n\tvolume = {8},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-204765},\n\tdoi = {10.1002/lol2.10305},\n\tabstract = {A longstanding challenge in stream ecology is to understand how landscape configuration organizes spatial patterns of ecosystem function via lateral groundwater connections. We combined laboratory ...},\n\tlanguage = {eng},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Lupon, Anna and Gómez-Gener, Lluís and Fork, Megan L. and Laudon, Hjalmar and Martí, Eugènia and Lidberg, William and Sponseller, Ryan A.},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {350--358},\n}\n\n\n\n\n\n\n\n\n\n A longstanding challenge in stream ecology is to understand how landscape configuration organizes spatial patterns of ecosystem function via lateral groundwater connections. We combined laboratory ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Widespread synchrony in phosphorus concentrations in northern lakes linked to winter temperature and summer precipitation.\n \n \n \n \n\n\n \n Isles, P. D. F.; Creed, I. F.; Hessen, D. O.; Kortelainen, P.; Paterson, M.; Pomati, F.; Rusak, J. A.; Vuorenmaa, J.; and Bergström, A.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 8(4): 639–648. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{isles_widespread_2023,\n\ttitle = {Widespread synchrony in phosphorus concentrations in northern lakes linked to winter temperature and summer precipitation},\n\tvolume = {8},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-205739},\n\tdoi = {10.1002/lol2.10318},\n\tabstract = {In recent years, unexplained declines in lake total phosphorus (TP) concentrations have been observed at northern latitudes (\\> 42°N latitude) where most of the world's lakes are found. We compil ...},\n\tlanguage = {eng},\n\tnumber = {4},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Isles, Peter D. F. and Creed, Irena F. and Hessen, Dag O. and Kortelainen, Pirkko and Paterson, Michael and Pomati, Francesco and Rusak, James A. and Vuorenmaa, Jussi and Bergström, Ann-Kristin},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {639--648},\n}\n\n\n\n\n\n In recent years, unexplained declines in lake total phosphorus (TP) concentrations have been observed at northern latitudes (> 42°N latitude) where most of the world's lakes are found. We compil ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting impacts of warming and browning on periphyton.\n \n \n \n \n\n\n \n Callisto Puts, I.; Ask, J.; Myrstener, M.; and Bergström, A.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 8(4): 628–638. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{callisto_puts_contrasting_2023,\n\ttitle = {Contrasting impacts of warming and browning on periphyton},\n\tvolume = {8},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-205740},\n\tdoi = {10.1002/lol2.10317},\n\tabstract = {We tested interactive effects of warming (+2°C) and browning on periphyton accrual and pigment composition when grown on a synthetic substrate (plastic strips) in the euphotic zone of 16 experiment ...},\n\tlanguage = {eng},\n\tnumber = {4},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Callisto Puts, Isolde and Ask, Jenny and Myrstener, Maria and Bergström, Ann-Kristin},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {628--638},\n}\n\n\n\n\n\n\n\n\n\n We tested interactive effects of warming (+2°C) and browning on periphyton accrual and pigment composition when grown on a synthetic substrate (plastic strips) in the euphotic zone of 16 experiment ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Response of lake metabolism to catchment inputs inferred using high-frequency lake and stream data from across the northern hemisphere.\n \n \n \n \n\n\n \n Corman, J. R.; Zwart, J. A.; Klug, J.; Bruesewitz, D. A.; de Eyto, E.; Klaus, M.; Knoll, L. B.; Rusak, J. A.; Vanni, M. J.; Alfonso, M. B.; Fernandez, R. L.; Yao, H.; Austnes, K.; Couture, R.; de Wit, H. A.; Karlsson, J.; and Laas, A.\n\n\n \n\n\n\n Limnology and Oceanography, 68(12): 2617–2631. 2023.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{corman_response_2023,\n\ttitle = {Response of lake metabolism to catchment inputs inferred using high-frequency lake and stream data from across the northern hemisphere},\n\tvolume = {68},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-216880},\n\tdoi = {10.1002/lno.12449},\n\tabstract = {In lakes, the rates of gross primary production (GPP), ecosystem respiration (R), and net ecosystem production (NEP) are often controlled by resource availability. Herein, we explore how catchment ...},\n\tlanguage = {eng},\n\tnumber = {12},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Corman, Jessica R. and Zwart, Jacob A. and Klug, Jennifer and Bruesewitz, Denise A. and de Eyto, Elvira and Klaus, Marcus and Knoll, Lesley B. and Rusak, James A. and Vanni, Michael J. and Alfonso, María Belén and Fernandez, Rocio Luz and Yao, Huaxia and Austnes, Kari and Couture, Raoul-Marie and de Wit, Heleen A. and Karlsson, Jan and Laas, Alo},\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {2617--2631},\n}\n\n\n\n\n\n In lakes, the rates of gross primary production (GPP), ecosystem respiration (R), and net ecosystem production (NEP) are often controlled by resource availability. Herein, we explore how catchment ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Lake bathymetry as driver of salmonid population size structure and biomass.\n \n \n \n \n\n\n \n Norman, S.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2023.\n Publisher: Umeå universitet\n\n\n\n
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\n\n\n@phdthesis{norman_lake_2023,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Lake bathymetry as driver of salmonid population size structure and biomass},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-203635},\n\tabstract = {Most fish species undergo ontogenetic niche shifts from feeding on pelagic zooplankton, to larger benthic invertebrates and in some cases also to fish. These ontogenetic niche shifts have strong im ...},\n\tlanguage = {eng},\n\turldate = {2023-07-25},\n\tschool = {Umeå University},\n\tauthor = {Norman, Sven},\n\tcollaborator = {Byström, Pär and Nilsson, Karin A. and Karlsson, Jan},\n\tyear = {2023},\n\tnote = {Publisher: Umeå universitet},\n\tkeywords = {⛔ No DOI found},\n}\n\n\n\n\n\n Most fish species undergo ontogenetic niche shifts from feeding on pelagic zooplankton, to larger benthic invertebrates and in some cases also to fish. These ontogenetic niche shifts have strong im ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Mapping trait versus species turnover reveals spatiotemporal variation in functional redundancy and network robustness in a plant-pollinator community.\n \n \n \n \n\n\n \n Cantwell-Jones, A.; Larson, K.; Ward, A.; Bates, O. K.; Cox, T.; Gibbons, C.; Richardson, R.; Al-Hayali, A. M. R.; Svedin, J.; Aronsson, M.; Brannlund, F.; Tylianakis, J. M.; Johansson, J.; and Gill, R. J.\n\n\n \n\n\n\n Functional Ecology, 37(3): 748–762. March 2023.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{cantwell-jones_mapping_2023,\n\ttitle = {Mapping trait versus species turnover reveals spatiotemporal variation in functional redundancy and network robustness in a plant-pollinator community},\n\tvolume = {37},\n\tissn = {0269-8463},\n\turl = {https://doi.org/10.1111/1365-2435.14253},\n\tdoi = {10.1111/1365-2435.14253},\n\tabstract = {Abstract Functional overlap among species (redundancy) is considered important in shaping competitive and mutualistic interactions that determine how communities respond to environmental change. Most studies view functional redundancy as static, yet traits within species?which ultimately shape functional redundancy?can vary over seasonal or spatial gradients. We therefore have limited understanding of how trait turnover within and between species could lead to changes in functional redundancy or how loss of traits could differentially impact mutualistic interactions depending on where and when the interactions occur in space and time. Using an Arctic bumblebee community as a case study, and 1277 individual measures from 14 species over three annual seasons, we quantified how inter- and intraspecific body-size turnover compared to species turnover with elevation and over the season. Coupling every individual and their trait with a plant visitation, we investigated how grouping individuals by a morphological trait or by species identity altered our assessment of network structure and how this differed in space and time. Finally, we tested how the sensitivity of the network in space and time differed when simulating extinction of nodes representing either morphological trait similarity or traditional species groups. This allowed us to explore the degree to which trait-based groups increase or decrease interaction redundancy relative to species-based nodes. We found that (i) groups of taxonomically and morphologically similar bees turn over in space and time independently from each other, with trait turnover being larger over the season; (ii) networks composed of nodes representing species versus morphologically similar bees were structured differently; and (iii) simulated loss of bee trait groups caused faster coextinction of bumblebee species and flowering plants than when bee taxonomic groups were lost. Crucially, the magnitude of these effects varied in space and time, highlighting the importance of considering spatiotemporal context when studying the relative importance of taxonomic and trait contributions to interaction network architecture. Our finding that functional redundancy varies spatiotemporally demonstrates how considering the traits of individuals within networks is needed to understand the impacts of environmental variation and extinction on ecosystem functioning and resilience. Read the free Plain Language Summary for this article on the Journal blog.},\n\tnumber = {3},\n\turldate = {2023-07-22},\n\tjournal = {Functional Ecology},\n\tauthor = {Cantwell-Jones, Aoife and Larson, Keith and Ward, Alan and Bates, Olivia K. and Cox, Tara and Gibbons, Charlotte and Richardson, Ryan and Al-Hayali, Abdullah M. R. and Svedin, Johan and Aronsson, Max and Brannlund, Frida and Tylianakis, Jason M. and Johansson, Jacob and Gill, Richard J.},\n\tmonth = mar,\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Arctic, Bombus community, altitudinal gradient, beta diversity, bumblebees, connectance, ecological network, modularity, pollination, sequential extinction, thermal cline},\n\tpages = {748--762},\n}\n\n\n\n\n\n Abstract Functional overlap among species (redundancy) is considered important in shaping competitive and mutualistic interactions that determine how communities respond to environmental change. Most studies view functional redundancy as static, yet traits within species?which ultimately shape functional redundancy?can vary over seasonal or spatial gradients. We therefore have limited understanding of how trait turnover within and between species could lead to changes in functional redundancy or how loss of traits could differentially impact mutualistic interactions depending on where and when the interactions occur in space and time. Using an Arctic bumblebee community as a case study, and 1277 individual measures from 14 species over three annual seasons, we quantified how inter- and intraspecific body-size turnover compared to species turnover with elevation and over the season. Coupling every individual and their trait with a plant visitation, we investigated how grouping individuals by a morphological trait or by species identity altered our assessment of network structure and how this differed in space and time. Finally, we tested how the sensitivity of the network in space and time differed when simulating extinction of nodes representing either morphological trait similarity or traditional species groups. This allowed us to explore the degree to which trait-based groups increase or decrease interaction redundancy relative to species-based nodes. We found that (i) groups of taxonomically and morphologically similar bees turn over in space and time independently from each other, with trait turnover being larger over the season; (ii) networks composed of nodes representing species versus morphologically similar bees were structured differently; and (iii) simulated loss of bee trait groups caused faster coextinction of bumblebee species and flowering plants than when bee taxonomic groups were lost. Crucially, the magnitude of these effects varied in space and time, highlighting the importance of considering spatiotemporal context when studying the relative importance of taxonomic and trait contributions to interaction network architecture. Our finding that functional redundancy varies spatiotemporally demonstrates how considering the traits of individuals within networks is needed to understand the impacts of environmental variation and extinction on ecosystem functioning and resilience. Read the free Plain Language Summary for this article on the Journal blog.\n
\n\n\n\n \n\n \n \n \n \n \n \n Wide-spread microbial sulfate reduction (MSR) in northern European freshwater systems: Drivers, magnitudes and seasonality.\n \n \n \n \n\n\n \n Fischer, S.; Mörth, C.; Rosqvist, G.; Giesler, R.; and Jarsjö, J.\n\n\n \n\n\n\n Science of The Total Environment, 889: 163764. September 2023.\n \n\n\n\n
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\n\n\n@article{fischer_wide-spread_2023,\n\ttitle = {Wide-spread microbial sulfate reduction ({MSR}) in northern {European} freshwater systems: {Drivers}, magnitudes and seasonality},\n\tvolume = {889},\n\tissn = {0048-9697},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969723023859},\n\tdoi = {10.1016/j.scitotenv.2023.163764},\n\tabstract = {Microbial sulfate reduction (MSR), which transforms sulfate into sulfide through the consumption of organic matter, is an integral part of sulfur and carbon cycling. Yet, the knowledge on MSR magnitudes is limited and mostly restricted to snap-shot conditions in specific surface water bodies. Potential impacts of MSR have consequently been unaccounted for, e.g., in regional or global weathering budgets. Here, we synthesize results from previous studies on sulfur isotope dynamics in stream water samples and apply a sulfur isotopic fractionation and mixing scheme combined with Monte Carlo simulations to derive MSR in entire hydrological catchments. This allowed comparison of magnitudes both within and between five study areas located between southern Sweden and the Kola Peninsula, Russia. Our results showed that the freshwater MSR ranged from 0 to 79 \\% (interquartile range of 19 percentage units) locally within the catchments, with average values from 2 to 28 \\% between the catchments, displaying a non-negligible catchment-average value of 13 \\%. The combined abundance or deficiency of several landscape elements (e.g., the areal percentage of forest and lakes/wetlands) were found to indicate relatively well whether or not catchment-scale MSR would be high. A regression analysis showed specifically that average slope was the individual element that best reflected the MSR magnitude, both at sub-catchment scale and between the different study areas. However, the regression results of individual parameters were generally weak. The MSR-values additionally showed differences between seasons, in particular in wetland/lake dominated catchments. Here MSR was high during the spring flood, which is consistent with the mobilization of water that under low-flow winter periods have developed the needed anoxic conditions for sulfate-reducing microorganisms. This study presents for the first time compelling evidence from multiple catchments of wide-spread MSR at levels slightly above 10 \\%, implying that the terrestrial pyrite oxidation may be underestimated in global weathering budgets.},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Fischer, Sandra and Mörth, Carl-Magnus and Rosqvist, Gunhild and Giesler, Reiner and Jarsjö, Jerker},\n\tmonth = sep,\n\tyear = {2023},\n\tkeywords = {Bacterial sulfate reduction, Global weathering budget, Indicators, Sulfur isotopes},\n\tpages = {163764},\n}\n\n\n\n\n\n Microbial sulfate reduction (MSR), which transforms sulfate into sulfide through the consumption of organic matter, is an integral part of sulfur and carbon cycling. Yet, the knowledge on MSR magnitudes is limited and mostly restricted to snap-shot conditions in specific surface water bodies. Potential impacts of MSR have consequently been unaccounted for, e.g., in regional or global weathering budgets. Here, we synthesize results from previous studies on sulfur isotope dynamics in stream water samples and apply a sulfur isotopic fractionation and mixing scheme combined with Monte Carlo simulations to derive MSR in entire hydrological catchments. This allowed comparison of magnitudes both within and between five study areas located between southern Sweden and the Kola Peninsula, Russia. Our results showed that the freshwater MSR ranged from 0 to 79 % (interquartile range of 19 percentage units) locally within the catchments, with average values from 2 to 28 % between the catchments, displaying a non-negligible catchment-average value of 13 %. The combined abundance or deficiency of several landscape elements (e.g., the areal percentage of forest and lakes/wetlands) were found to indicate relatively well whether or not catchment-scale MSR would be high. A regression analysis showed specifically that average slope was the individual element that best reflected the MSR magnitude, both at sub-catchment scale and between the different study areas. However, the regression results of individual parameters were generally weak. The MSR-values additionally showed differences between seasons, in particular in wetland/lake dominated catchments. Here MSR was high during the spring flood, which is consistent with the mobilization of water that under low-flow winter periods have developed the needed anoxic conditions for sulfate-reducing microorganisms. This study presents for the first time compelling evidence from multiple catchments of wide-spread MSR at levels slightly above 10 %, implying that the terrestrial pyrite oxidation may be underestimated in global weathering budgets.\n
\n\n\n\n \n\n \n \n \n \n \n \n Ideas and perspectives: Alleviation of functional limitations by soil organisms is key to climate feedbacks from arctic soils.\n \n \n \n \n\n\n \n Blume-Werry, G.; Klaminder, J.; Krab, E. J.; and Monteux, S.\n\n\n \n\n\n\n Biogeosciences, 20(10): 1979–1990. 2023.\n \n\n\n\n
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\n\n\n\n@article{blume-werry_ideas_2023,\n\ttitle = {Ideas and perspectives: {Alleviation} of functional limitations by soil organisms is key to climate feedbacks from arctic soils},\n\tvolume = {20},\n\turl = {https://bg.copernicus.org/articles/20/1979/2023/},\n\tdoi = {10.5194/bg-20-1979-2023},\n\tnumber = {10},\n\tjournal = {Biogeosciences},\n\tauthor = {Blume-Werry, G. and Klaminder, J. and Krab, E. J. and Monteux, S.},\n\tyear = {2023},\n\tpages = {1979--1990},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n The topological nature of tag jumping in environmental DNA metabarcoding studies.\n \n \n \n \n\n\n \n Rodriguez-Martinez, S.; Klaminder, J.; Morlock, M. A.; Dalén, L.; and Huang, D. Y.\n\n\n \n\n\n\n Molecular Ecology Resources, 23(3): 621–631. April 2023.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{rodriguez-martinez_topological_2023,\n\ttitle = {The topological nature of tag jumping in environmental {DNA} metabarcoding studies},\n\tvolume = {23},\n\tissn = {1755-098X},\n\turl = {https://doi.org/10.1111/1755-0998.13745},\n\tdoi = {10.1111/1755-0998.13745},\n\tabstract = {Abstract Metabarcoding of environmental DNA constitutes a state-of-the-art tool for environmental studies. One fundamental principle implicit in most metabarcoding studies is that individual sample amplicons can still be identified after being pooled with others?based on their unique combinations of tags?during the so-called demultiplexing step that follows sequencing. Nevertheless, it has been recognized that tags can sometimes be changed (i.e., tag jumping), which ultimately leads to sample crosstalk. Here, using four DNA metabarcoding data sets derived from the analysis of soils and sediments, we show that tag jumping follows very specific and systematic patterns. Specifically, we find a strong correlation between the number of reads in blank samples and their topological position in the tag matrix (described by vertical and horizontal vectors). This observed spatial pattern of artefactual sequences could be explained by polymerase activity, which leads to the exchange of the 3? tag of single stranded tagged sequences through the formation of heteroduplexes with mixed barcodes. Importantly, tag jumping substantially distorted our data sets?despite our use of methods suggested to minimize this error. We developed a topological model to estimate the noise based on the counts in our blanks, which suggested that 40\\%?80\\% of the taxa in our soil and sedimentary samples were likely false positives introduced through tag jumping. We highlight that the amount of false positive detections caused by tag jumping strongly biased our community analyses.},\n\tnumber = {3},\n\turldate = {2023-07-22},\n\tjournal = {Molecular Ecology Resources},\n\tauthor = {Rodriguez-Martinez, Saul and Klaminder, Jonatan and Morlock, Marina A. and Dalén, Love and Huang, Doreen Yu-Tuan},\n\tmonth = apr,\n\tyear = {2023},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {a-DNA, detection limits, e-DNA, false positive, index hopping, sample crosstalk},\n\tpages = {621--631},\n}\n\n\n\n\n\n Abstract Metabarcoding of environmental DNA constitutes a state-of-the-art tool for environmental studies. One fundamental principle implicit in most metabarcoding studies is that individual sample amplicons can still be identified after being pooled with others?based on their unique combinations of tags?during the so-called demultiplexing step that follows sequencing. Nevertheless, it has been recognized that tags can sometimes be changed (i.e., tag jumping), which ultimately leads to sample crosstalk. Here, using four DNA metabarcoding data sets derived from the analysis of soils and sediments, we show that tag jumping follows very specific and systematic patterns. Specifically, we find a strong correlation between the number of reads in blank samples and their topological position in the tag matrix (described by vertical and horizontal vectors). This observed spatial pattern of artefactual sequences could be explained by polymerase activity, which leads to the exchange of the 3? tag of single stranded tagged sequences through the formation of heteroduplexes with mixed barcodes. Importantly, tag jumping substantially distorted our data sets?despite our use of methods suggested to minimize this error. We developed a topological model to estimate the noise based on the counts in our blanks, which suggested that 40%?80% of the taxa in our soil and sedimentary samples were likely false positives introduced through tag jumping. We highlight that the amount of false positive detections caused by tag jumping strongly biased our community analyses.\n
\n\n\n\n \n\n \n \n \n \n \n \n Holes in the tundra: Invasive earthworms alter soil structure and moisture in tundra soils.\n \n \n \n \n\n\n \n Klaminder, J.; Krab, E.; Larsbo, M.; Jonsson, H.; Fransson, J.; and Koestel, J.\n\n\n \n\n\n\n Science of The Total Environment, 859: 160125. February 2023.\n \n\n\n\n
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\n\n\n@article{klaminder_holes_2023,\n\ttitle = {Holes in the tundra: {Invasive} earthworms alter soil structure and moisture in tundra soils},\n\tvolume = {859},\n\tissn = {0048-9697},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969722072254},\n\tdoi = {10.1016/j.scitotenv.2022.160125},\n\tabstract = {Human introductions have resulted in earthworms establishing in the Arctic, species known to cause cascading ecosystem change. However, few quantitative outdoor experiments have been performed that describe how these soil modifying earthworms are reshaping structures in tundra soils. In this study, we used three-dimensional (3-D) X-ray images of soil cores (approximately 10 cm diameter, 20 cm height, N = 48) to assess how earthworms (Aporrectodea sp. and Lumbricus sp.) affect soil structure and macropore networks in an outdoor mesocosm experiment that lasted four summers. Effects were assessed in both shrub-dominated (heath) and herb-dominated (meadow) tundra. Earthworms almost doubled the macroporosity in meadow soils and tripled macroporosity in heath. Interestingly, the fractal dimension of macropores decreased in response to earthworm burrowing in both systems, indicating that the presence of earthworms reduced the geometric complexity in comparison to other pore-generating processes active in the tundra. Observed effects on soil structure occurred along with a dramatically reduced soil moisture content, which was observed the first winter after earthworm introduction in the meadow. Our findings suggest that predictions of future changes in vegetation and soil carbon pools in the Arctic should include major impacts on soil properties that earthworms induce.},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Klaminder, J. and Krab, E.J. and Larsbo, M. and Jonsson, H. and Fransson, J. and Koestel, J.},\n\tmonth = feb,\n\tyear = {2023},\n\tkeywords = {3D, Abisko, Bioturbation, Heath, Long-term, Meadow, Soil-mixing},\n\tpages = {160125},\n}\n\n\n\n\n\n Human introductions have resulted in earthworms establishing in the Arctic, species known to cause cascading ecosystem change. However, few quantitative outdoor experiments have been performed that describe how these soil modifying earthworms are reshaping structures in tundra soils. In this study, we used three-dimensional (3-D) X-ray images of soil cores (approximately 10 cm diameter, 20 cm height, N = 48) to assess how earthworms (Aporrectodea sp. and Lumbricus sp.) affect soil structure and macropore networks in an outdoor mesocosm experiment that lasted four summers. Effects were assessed in both shrub-dominated (heath) and herb-dominated (meadow) tundra. Earthworms almost doubled the macroporosity in meadow soils and tripled macroporosity in heath. Interestingly, the fractal dimension of macropores decreased in response to earthworm burrowing in both systems, indicating that the presence of earthworms reduced the geometric complexity in comparison to other pore-generating processes active in the tundra. Observed effects on soil structure occurred along with a dramatically reduced soil moisture content, which was observed the first winter after earthworm introduction in the meadow. Our findings suggest that predictions of future changes in vegetation and soil carbon pools in the Arctic should include major impacts on soil properties that earthworms induce.\n
\n\n\n\n \n\n \n \n \n \n \n \n Catchment characteristics control boreal mire nutrient regime and vegetation patterns over ~5000 years of landscape development.\n \n \n \n \n\n\n \n Ehnvall, B.; Ågren, A. M.; Nilsson, M. B.; Ratcliffe, J. L.; Noumonvi, K. D.; Peichl, M.; Lidberg, W.; Giesler, R.; Mörth, C.; and Öquist, M. G.\n\n\n \n\n\n\n Science of The Total Environment, 895: 165132. October 2023.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{ehnvall_catchment_2023,\n\ttitle = {Catchment characteristics control boreal mire nutrient regime and vegetation patterns over {\\textasciitilde}5000 years of landscape development},\n\tvolume = {895},\n\tissn = {0048-9697},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969723037555},\n\tdoi = {10.1016/j.scitotenv.2023.165132},\n\tabstract = {Vegetation holds the key to many properties that make natural mires unique, such as surface microtopography, high biodiversity values, effective carbon sequestration and regulation of water and nutrient fluxes across the landscape. Despite this, landscape controls behind mire vegetation patterns have previously been poorly described at large spatial scales, which limits the understanding of basic drivers underpinning mire ecosystem services. We studied catchment controls on mire nutrient regimes and vegetation patterns using a geographically constrained natural mire chronosequence along the isostatically rising coastline in Northern Sweden. By comparing mires of different ages, we can partition vegetation patterns caused by long-term mire succession ({\\textless}5000 years) and present-day vegetation responses to catchment eco-hydrological settings. We used the remote sensing based normalized difference vegetation index (NDVI) to describe mire vegetation and combined peat physicochemical measures with catchment properties to identify the most important factors that determine mire NDVI. We found strong evidence that mire NDVI depends on nutrient inputs from the catchment area or underlying mineral soil, especially concerning phosphorus and potassium concentrations. Steep mire and catchment slopes, dry conditions and large catchment areas relative to mire areas were associated with higher NDVI. We also found long-term successional patterns, with lower NDVI in older mires. Importantly, the NDVI should be used to describe mire vegetation patterns in open mires if the focus is on surface vegetation, since the canopy cover in tree-covered mires completely dominated the NDVI signal. With our study approach, we can quantitatively describe the connection between landscape properties and mire nutrient regime. Our results confirm that mire vegetation responds to the upslope catchment area, but importantly, also suggest that mire and catchment aging can override the role of catchment influence. This effect was clear across mires of all ages, but was strongest in younger mires.},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Ehnvall, Betty and Ågren, Anneli M. and Nilsson, Mats B. and Ratcliffe, Joshua L. and Noumonvi, Koffi Dodji and Peichl, Matthias and Lidberg, William and Giesler, Reiner and Mörth, Carl-Magnus and Öquist, Mats G.},\n\tmonth = oct,\n\tyear = {2023},\n\tkeywords = {\\#nosource, Catchment support, Chronosequence, Holocene, Landscape ecology, NDVI},\n\tpages = {165132},\n}\n\n\n\n\n\n Vegetation holds the key to many properties that make natural mires unique, such as surface microtopography, high biodiversity values, effective carbon sequestration and regulation of water and nutrient fluxes across the landscape. Despite this, landscape controls behind mire vegetation patterns have previously been poorly described at large spatial scales, which limits the understanding of basic drivers underpinning mire ecosystem services. We studied catchment controls on mire nutrient regimes and vegetation patterns using a geographically constrained natural mire chronosequence along the isostatically rising coastline in Northern Sweden. By comparing mires of different ages, we can partition vegetation patterns caused by long-term mire succession (\\textless5000 years) and present-day vegetation responses to catchment eco-hydrological settings. We used the remote sensing based normalized difference vegetation index (NDVI) to describe mire vegetation and combined peat physicochemical measures with catchment properties to identify the most important factors that determine mire NDVI. We found strong evidence that mire NDVI depends on nutrient inputs from the catchment area or underlying mineral soil, especially concerning phosphorus and potassium concentrations. Steep mire and catchment slopes, dry conditions and large catchment areas relative to mire areas were associated with higher NDVI. We also found long-term successional patterns, with lower NDVI in older mires. Importantly, the NDVI should be used to describe mire vegetation patterns in open mires if the focus is on surface vegetation, since the canopy cover in tree-covered mires completely dominated the NDVI signal. With our study approach, we can quantitatively describe the connection between landscape properties and mire nutrient regime. Our results confirm that mire vegetation responds to the upslope catchment area, but importantly, also suggest that mire and catchment aging can override the role of catchment influence. This effect was clear across mires of all ages, but was strongest in younger mires.\n
\n\n\n\n \n\n \n \n \n \n \n \n Synthesis of a B-Antigen Hexasaccharide, a B-Lewis b Heptasaccharide and Glycoconjugates Thereof to Investigate Binding Properties of Helicobacter pylori.\n \n \n \n \n\n\n \n Reihill, M.; Fournière, V.; Cheallaigh, A. N.; Edlund, J. O.; Miller, G. J.; Borén, T.; Lahmann, M.; and Oscarson, S.\n\n\n \n\n\n\n Chemistry – A European Journal, 29(16): e202203672. 2023.\n _eprint: https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10.1002/chem.202203672\n\n\n\n
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\n\n\n@article{reihill_synthesis_2023,\n\ttitle = {Synthesis of a {B}-{Antigen} {Hexasaccharide}, a {B}-{Lewis} b {Heptasaccharide} and {Glycoconjugates} {Thereof} to {Investigate} {Binding} {Properties} of {Helicobacter} pylori},\n\tvolume = {29},\n\turl = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202203672},\n\tdoi = {10.1002/chem.202203672},\n\tabstract = {Abstract Infecting the stomach of almost 50 \\% of people, Helicobacter pylori is a causative agent of gastritis, peptic ulcers and stomach cancers. Interactions between bacterial membrane-bound lectin, Blood group Antigen Binding Adhesin (BabA), and human blood group antigens are key in the initiation of infection. Herein, the synthesis of a B-antigen hexasaccharide (B6) and a B-Lewis b heptasaccharide (BLeb7) and Bovine Serum Albumin glycoconjugates thereof is reported to assess the binding properties and preferences of BabA from different strains. From a previously reported trisaccharide acceptor a versatile key Lacto-N-tetraose tetrasaccharide intermediate was synthesized, which allowed us to explore various routes to the final targets, either via initial introduction of fucosyl residues followed by introduction of the B-determinant or vice versa. The first approach proved unsuccessful, whereas the second afforded the target structures in good yields. Protein conjugation using isothiocyanate methodology allowed us to reach high glycan loadings (up to 23 per protein) to mimic multivalent displays encountered in Nature. Protein glycoconjugate inhibition binding studies were performed with H. pylori strains displaying high or low affinity for Lewis b hexasaccharide structures showing that the binding to the high affinity strain was reduced due to the presence of the B-determinant in the Bleb7-conjugates and further reduced by the absence of the Lewis fucose residue in the B6-conjugate.},\n\tnumber = {16},\n\tjournal = {Chemistry – A European Journal},\n\tauthor = {Reihill, Mark and Fournière, Viviane and Cheallaigh, Aisling Ní and Edlund, Johan Olofsson and Miller, Gavin John and Borén, Thomas and Lahmann, Martina and Oscarson, Stefan},\n\tyear = {2023},\n\tnote = {\\_eprint: https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10.1002/chem.202203672},\n\tkeywords = {\\#nosource, B antigen, B-Lewis b, glycoconjugate, synthesis, thioglycoside},\n\tpages = {e202203672},\n}\n\n\n\n\n\n Abstract Infecting the stomach of almost 50 % of people, Helicobacter pylori is a causative agent of gastritis, peptic ulcers and stomach cancers. Interactions between bacterial membrane-bound lectin, Blood group Antigen Binding Adhesin (BabA), and human blood group antigens are key in the initiation of infection. Herein, the synthesis of a B-antigen hexasaccharide (B6) and a B-Lewis b heptasaccharide (BLeb7) and Bovine Serum Albumin glycoconjugates thereof is reported to assess the binding properties and preferences of BabA from different strains. From a previously reported trisaccharide acceptor a versatile key Lacto-N-tetraose tetrasaccharide intermediate was synthesized, which allowed us to explore various routes to the final targets, either via initial introduction of fucosyl residues followed by introduction of the B-determinant or vice versa. The first approach proved unsuccessful, whereas the second afforded the target structures in good yields. Protein conjugation using isothiocyanate methodology allowed us to reach high glycan loadings (up to 23 per protein) to mimic multivalent displays encountered in Nature. Protein glycoconjugate inhibition binding studies were performed with H. pylori strains displaying high or low affinity for Lewis b hexasaccharide structures showing that the binding to the high affinity strain was reduced due to the presence of the B-determinant in the Bleb7-conjugates and further reduced by the absence of the Lewis fucose residue in the B6-conjugate.\n
\n\n\n\n \n\n \n \n \n \n \n \n Top-down and bottom-up forces explain patch utilization by two deer species and forest recruitment.\n \n \n \n \n\n\n \n Ramirez, J. I.; Poorter, L.; Jansen, P. A.; den Ouden, J.; Siewert, M.; and Olofsson, J.\n\n\n \n\n\n\n Oecologia, 201(1): 229–240. January 2023.\n \n\n\n\n
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\n\n\n@article{ramirez_top-down_2023,\n\ttitle = {Top-down and bottom-up forces explain patch utilization by two deer species and forest recruitment},\n\tvolume = {201},\n\tissn = {1432-1939},\n\turl = {https://doi.org/10.1007/s00442-022-05292-8},\n\tdoi = {10.1007/s00442-022-05292-8},\n\tabstract = {Ungulates play an important role in temperate systems. Through their feeding behaviour, they can respond to vegetation by selecting patches or modify vegetation composition by herbivory. The degree in which they interact with vegetation can either reinforce landscape heterogeneity by creating disturbance or reduce heterogeneity in case of overbrowsing. This study evaluates how bottom-up (patch quality, structure), top-down forces (hunting, distance to village, forest edge) and deer features (feeding type, abundance) mediate patch utilization in a temperate forest and assess the implications of patch utilization and light on forest recruitment. Theory predicts that animals seek to maximize their energetic gains by food intake while minimizing the costs associated to foraging, such as the energy required for avoiding predators and exploiting resources. We focused on two deer species with contrasting feeding type: a browser (C. capreolus) and a mixed feeder (C. elaphus). We paired camera traps to vegetation sub-plots in ten forest sites in the Netherlands that widely ranged in deer abundance and landscape heterogeneity. Results showed that patch utilization is simultaneously explained by bottom-up, top-down forces and by deer abundance, as predicted by the safety-in-numbers hypothesis. Yet, forces best explaining patch utilization differed between deer species. Overall, higher patch utilization came with higher browsing, lower tree diversity and a large difference in forest composition: from a mix of broadleaves and conifers towards only conifers. We conclude that these two deer species, although living in the same area and belonging to the same guild, differentially perceive, interact with and shape their surrounding landscape.},\n\tnumber = {1},\n\tjournal = {Oecologia},\n\tauthor = {Ramirez, J. Ignacio and Poorter, Lourens and Jansen, Patrick A. and den Ouden, Jan and Siewert, Matthias and Olofsson, Johan},\n\tmonth = jan,\n\tyear = {2023},\n\tkeywords = {\\#nosource},\n\tpages = {229--240},\n}\n\n\n\n\n\n Ungulates play an important role in temperate systems. Through their feeding behaviour, they can respond to vegetation by selecting patches or modify vegetation composition by herbivory. The degree in which they interact with vegetation can either reinforce landscape heterogeneity by creating disturbance or reduce heterogeneity in case of overbrowsing. This study evaluates how bottom-up (patch quality, structure), top-down forces (hunting, distance to village, forest edge) and deer features (feeding type, abundance) mediate patch utilization in a temperate forest and assess the implications of patch utilization and light on forest recruitment. Theory predicts that animals seek to maximize their energetic gains by food intake while minimizing the costs associated to foraging, such as the energy required for avoiding predators and exploiting resources. We focused on two deer species with contrasting feeding type: a browser (C. capreolus) and a mixed feeder (C. elaphus). We paired camera traps to vegetation sub-plots in ten forest sites in the Netherlands that widely ranged in deer abundance and landscape heterogeneity. Results showed that patch utilization is simultaneously explained by bottom-up, top-down forces and by deer abundance, as predicted by the safety-in-numbers hypothesis. Yet, forces best explaining patch utilization differed between deer species. Overall, higher patch utilization came with higher browsing, lower tree diversity and a large difference in forest composition: from a mix of broadleaves and conifers towards only conifers. We conclude that these two deer species, although living in the same area and belonging to the same guild, differentially perceive, interact with and shape their surrounding landscape.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting plant–soil–microbial feedbacks stabilize vegetation types and uncouple topsoil C and N stocks across a subarctic–alpine landscape.\n \n \n \n \n\n\n \n Castaño, C.; Hallin, S.; Egelkraut, D.; Lindahl, B. D.; Olofsson, J.; and Clemmensen, K. E.\n\n\n \n\n\n\n New Phytologist, 238(6): 2621–2633. 2023.\n _eprint: https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.18679\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{castano_contrasting_2023,\n\ttitle = {Contrasting plant–soil–microbial feedbacks stabilize vegetation types and uncouple topsoil {C} and {N} stocks across a subarctic–alpine landscape},\n\tvolume = {238},\n\turl = {https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.18679},\n\tdoi = {10.1111/nph.18679},\n\tabstract = {Summary Global vegetation regimes vary in belowground carbon (C) and nitrogen (N) dynamics. However, disentangling large-scale climatic controls from the effects of intrinsic plant–soil–microbial feedbacks on belowground processes is challenging. In local gradients with similar pedo-climatic conditions, effects of plant–microbial feedbacks may be isolated from large-scale drivers. Across a subarctic–alpine mosaic of historic grazing fields and surrounding heath and birch forest, we evaluated whether vegetation-specific plant–microbial feedbacks involved contrasting N cycling characteristics and C and N stocks in the organic topsoil. We sequenced soil fungi, quantified functional genes within the inorganic N cycle, and measured 15N natural abundance. In grassland soils, large N stocks and low C : N ratios associated with fungal saprotrophs, archaeal ammonia oxidizers, and bacteria capable of respiratory ammonification, indicating maintained inorganic N cycling a century after abandoned reindeer grazing. Toward forest and heath, increasing abundance of mycorrhizal fungi co-occurred with transition to organic N cycling. However, ectomycorrhizal fungal decomposers correlated with small soil N and C stocks in forest, while root-associated ascomycetes associated with small N but large C stocks in heath, uncoupling C and N storage across vegetation types. We propose that contrasting, positive plant–microbial feedbacks stabilize vegetation trajectories, resulting in diverging soil C : N ratios at the landscape scale.},\n\tnumber = {6},\n\tjournal = {New Phytologist},\n\tauthor = {Castaño, Carles and Hallin, Sara and Egelkraut, Dagmar and Lindahl, Björn D. and Olofsson, Johan and Clemmensen, Karina Engelbrecht},\n\tyear = {2023},\n\tnote = {\\_eprint: https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.18679},\n\tkeywords = {\\#nosource, N cycling, forest, fungal saprotrophs, grassland, heathland, mycorrhiza, vegetation gradients},\n\tpages = {2621--2633},\n}\n\n\n\n\n\n Summary Global vegetation regimes vary in belowground carbon (C) and nitrogen (N) dynamics. However, disentangling large-scale climatic controls from the effects of intrinsic plant–soil–microbial feedbacks on belowground processes is challenging. In local gradients with similar pedo-climatic conditions, effects of plant–microbial feedbacks may be isolated from large-scale drivers. Across a subarctic–alpine mosaic of historic grazing fields and surrounding heath and birch forest, we evaluated whether vegetation-specific plant–microbial feedbacks involved contrasting N cycling characteristics and C and N stocks in the organic topsoil. We sequenced soil fungi, quantified functional genes within the inorganic N cycle, and measured 15N natural abundance. In grassland soils, large N stocks and low C : N ratios associated with fungal saprotrophs, archaeal ammonia oxidizers, and bacteria capable of respiratory ammonification, indicating maintained inorganic N cycling a century after abandoned reindeer grazing. Toward forest and heath, increasing abundance of mycorrhizal fungi co-occurred with transition to organic N cycling. However, ectomycorrhizal fungal decomposers correlated with small soil N and C stocks in forest, while root-associated ascomycetes associated with small N but large C stocks in heath, uncoupling C and N storage across vegetation types. We propose that contrasting, positive plant–microbial feedbacks stabilize vegetation trajectories, resulting in diverging soil C : N ratios at the landscape scale.\n
\n\n\n\n \n\n \n \n \n \n \n \n Linkages between Sphagnum metabolites and peatland CO2 uptake are sensitive to seasonality in warming trends.\n \n \n \n \n\n\n \n Sytiuk, A.; Hamard, S.; Céréghino, R.; Dorrepaal, E.; Geissel, H.; Küttim, M.; Lamentowicz, M.; Tuittila, E. S.; and Jassey, V. E. J.\n\n\n \n\n\n\n New Phytologist, 237(4): 1164–1178. 2023.\n _eprint: https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.18601\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{sytiuk_linkages_2023,\n\ttitle = {Linkages between {Sphagnum} metabolites and peatland {CO2} uptake are sensitive to seasonality in warming trends},\n\tvolume = {237},\n\turl = {https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.18601},\n\tdoi = {10.1111/nph.18601},\n\tabstract = {Summary Plants produce a wide diversity of metabolites. Yet, our understanding of how shifts in plant metabolites as a response to climate change feedback on ecosystem processes remains scarce. Here, we test to what extent climate warming shifts the seasonality of metabolites produced by Sphagnum mosses, and what are the consequences of these shifts for peatland C uptake. We used a reciprocal transplant experiment along a climate gradient in Europe to simulate climate change. We evaluated the responses of primary and secondary metabolites in five Sphagnum species and related their responses to gross ecosystem productivity (GEP). When transplanted to a warmer climate, Sphagnum species showed consistent responses to warming, with an upregulation of either their primary or secondary metabolite according to seasons. Moreover, these shifts were correlated to changes in GEP, especially in spring and autumn. Our results indicate that the Sphagnum metabolome is very plastic and sensitive to warming. We also show that warming-induced changes in the seasonality of Sphagnum metabolites have consequences on peatland GEP. Our findings demonstrate the capacity for plant metabolic plasticity to impact ecosystem C processes and reveal a further mechanism through which Sphagnum could shape peatland responses to climate change.},\n\tnumber = {4},\n\tjournal = {New Phytologist},\n\tauthor = {Sytiuk, Anna and Hamard, Samuel and Céréghino, Régis and Dorrepaal, Ellen and Geissel, Honorine and Küttim, Martin and Lamentowicz, Mariusz and Tuittila, Eeva Stiina and Jassey, Vincent E. J.},\n\tyear = {2023},\n\tnote = {\\_eprint: https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.18601},\n\tkeywords = {\\#nosource, Sphagnum, carbon cycle, climate change, climate feedback, intraspecific variability, phenotypic plasticity, plant metabolism, seasonality},\n\tpages = {1164--1178},\n}\n\n\n\n\n\n Summary Plants produce a wide diversity of metabolites. Yet, our understanding of how shifts in plant metabolites as a response to climate change feedback on ecosystem processes remains scarce. Here, we test to what extent climate warming shifts the seasonality of metabolites produced by Sphagnum mosses, and what are the consequences of these shifts for peatland C uptake. We used a reciprocal transplant experiment along a climate gradient in Europe to simulate climate change. We evaluated the responses of primary and secondary metabolites in five Sphagnum species and related their responses to gross ecosystem productivity (GEP). When transplanted to a warmer climate, Sphagnum species showed consistent responses to warming, with an upregulation of either their primary or secondary metabolite according to seasons. Moreover, these shifts were correlated to changes in GEP, especially in spring and autumn. Our results indicate that the Sphagnum metabolome is very plastic and sensitive to warming. We also show that warming-induced changes in the seasonality of Sphagnum metabolites have consequences on peatland GEP. Our findings demonstrate the capacity for plant metabolic plasticity to impact ecosystem C processes and reveal a further mechanism through which Sphagnum could shape peatland responses to climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Browning affects pelagic productivity in northern lakes by surface water warming and carbon fertilization.\n \n \n \n \n\n\n \n Puts, I. C.; Ask, J.; Deininger, A.; Jonsson, A.; Karlsson, J.; and Bergström, A.\n\n\n \n\n\n\n Global Change Biology, 29(2): 375–390. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.16469\n\n\n\n
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\n\n\n@article{puts_browning_2023,\n\ttitle = {Browning affects pelagic productivity in northern lakes by surface water warming and carbon fertilization},\n\tvolume = {29},\n\tcopyright = {© 2022 The Authors. Global Change Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.16469},\n\tdoi = {10.1111/gcb.16469},\n\tabstract = {Global change impacts important environmental drivers for pelagic gross primary production (GPP) in northern lakes, such as temperature, light, nutrient, and inorganic carbon availability. Separate and/or synergistic impacts of these environmental drivers on pelagic GPP remain largely unresolved. Here, we assess key drivers of pelagic GPP by combining detailed depth profiles of summer pelagic GPP with environmental and climatic data across 45 small and shallow lakes across northern Sweden (20 boreal, 6 subarctic, and 19 arctic lakes). We found that across lakes summer pelagic GPP was strongest associated with lake water temperatures, lake carbon dioxide (CO2) concentrations impacted by lake water pH, and further moderated by dissolved organic carbon (DOC) concentrations influencing light and nutrient conditions. We further used this dataset to assess the extent of additional DOC-induced warming of epilimnia (here named internal warming), which was especially pronounced in shallow lakes (decreasing 0.96°C for every decreasing m in average lake depth) and increased with higher concentrations of DOC. Additionally, the total pools and relative proportion of dissolved inorganic carbon and DOC, further influenced pelagic GPP with drivers differing slightly among the boreal, subarctic and Arctic biomes. Our study provides novel insights in that global change affects pelagic GPP in northern lakes not only by modifying the organic carbon cycle and light and nutrient conditions, but also through modifications of inorganic carbon supply and temperature. Considering the large-scale impacts and similarities of global warming, browning and recovery from acidification of lakes at higher latitudes throughout the northern hemisphere, these changes are likely to operate on a global scale.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2023-07-20},\n\tjournal = {Global Change Biology},\n\tauthor = {Puts, Isolde C. and Ask, Jenny and Deininger, Anne and Jonsson, Anders and Karlsson, Jan and Bergström, Ann-Kristin},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.16469},\n\tkeywords = {\\#nosource, DOC, acidification, bicarbonate system, inorganic carbon, primary production, stoichiometry, supersaturation, temperature},\n\tpages = {375--390},\n}\n\n\n\n\n\n Global change impacts important environmental drivers for pelagic gross primary production (GPP) in northern lakes, such as temperature, light, nutrient, and inorganic carbon availability. Separate and/or synergistic impacts of these environmental drivers on pelagic GPP remain largely unresolved. Here, we assess key drivers of pelagic GPP by combining detailed depth profiles of summer pelagic GPP with environmental and climatic data across 45 small and shallow lakes across northern Sweden (20 boreal, 6 subarctic, and 19 arctic lakes). We found that across lakes summer pelagic GPP was strongest associated with lake water temperatures, lake carbon dioxide (CO2) concentrations impacted by lake water pH, and further moderated by dissolved organic carbon (DOC) concentrations influencing light and nutrient conditions. We further used this dataset to assess the extent of additional DOC-induced warming of epilimnia (here named internal warming), which was especially pronounced in shallow lakes (decreasing 0.96°C for every decreasing m in average lake depth) and increased with higher concentrations of DOC. Additionally, the total pools and relative proportion of dissolved inorganic carbon and DOC, further influenced pelagic GPP with drivers differing slightly among the boreal, subarctic and Arctic biomes. Our study provides novel insights in that global change affects pelagic GPP in northern lakes not only by modifying the organic carbon cycle and light and nutrient conditions, but also through modifications of inorganic carbon supply and temperature. Considering the large-scale impacts and similarities of global warming, browning and recovery from acidification of lakes at higher latitudes throughout the northern hemisphere, these changes are likely to operate on a global scale.\n
\n\n\n\n \n\n \n \n \n \n \n \n Higher Apparent Gas Transfer Velocities for CO2 Compared to CH4 in Small Lakes.\n \n \n \n \n\n\n \n Pajala, G.; Rudberg, D.; Gålfalk, M.; Melack, J. M.; Macintyre, S.; Karlsson, J.; Sawakuchi, H. O.; Schenk, J.; Sieczko, A.; Sundgren, I.; Duc, N. T.; and Bastviken, D.\n\n\n \n\n\n\n Environmental Science & Technology, 57(23): 8578–8587. June 2023.\n Publisher: American Chemical Society\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{pajala_higher_2023,\n\ttitle = {Higher {Apparent} {Gas} {Transfer} {Velocities} for {CO2} {Compared} to {CH4} in {Small} {Lakes}},\n\tvolume = {57},\n\tissn = {0013-936X},\n\turl = {https://doi.org/10.1021/acs.est.2c09230},\n\tdoi = {10.1021/acs.est.2c09230},\n\tabstract = {Large greenhouse gas emissions occur via the release of carbon dioxide (CO2) and methane (CH4) from the surface layer of lakes. Such emissions are modeled from the air–water gas concentration gradient and the gas transfer velocity (k). The links between k and the physical properties of the gas and water have led to the development of methods to convert k between gases through Schmidt number normalization. However, recent observations have found that such normalization of apparent k estimates from field measurements can yield different results for CH4 and CO2. We estimated k for CO2 and CH4 from measurements of concentration gradients and fluxes in four contrasting lakes and found consistently higher (on an average 1.7 times) normalized apparent k values for CO2 than CH4. From these results, we infer that several gas-specific factors, including chemical and biological processes within the water surface microlayer, can influence apparent k estimates. We highlight the importance of accurately measuring relevant air–water gas concentration gradients and considering gas-specific processes when estimating k.},\n\tnumber = {23},\n\turldate = {2023-07-20},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Pajala, Gustav and Rudberg, David and Gålfalk, Magnus and Melack, John Michael and Macintyre, Sally and Karlsson, Jan and Sawakuchi, Henrique Oliveira and Schenk, Jonathan and Sieczko, Anna and Sundgren, Ingrid and Duc, Nguyen Thanh and Bastviken, David},\n\tmonth = jun,\n\tyear = {2023},\n\tnote = {Publisher: American Chemical Society},\n\tkeywords = {\\#nosource},\n\tpages = {8578--8587},\n}\n\n\n\n\n\n Large greenhouse gas emissions occur via the release of carbon dioxide (CO2) and methane (CH4) from the surface layer of lakes. Such emissions are modeled from the air–water gas concentration gradient and the gas transfer velocity (k). The links between k and the physical properties of the gas and water have led to the development of methods to convert k between gases through Schmidt number normalization. However, recent observations have found that such normalization of apparent k estimates from field measurements can yield different results for CH4 and CO2. We estimated k for CO2 and CH4 from measurements of concentration gradients and fluxes in four contrasting lakes and found consistently higher (on an average 1.7 times) normalized apparent k values for CO2 than CH4. From these results, we infer that several gas-specific factors, including chemical and biological processes within the water surface microlayer, can influence apparent k estimates. We highlight the importance of accurately measuring relevant air–water gas concentration gradients and considering gas-specific processes when estimating k.\n
\n\n\n\n \n\n \n \n \n \n \n \n Experimental warming and browning influence autumnal pelagic and benthic invertebrate biomass and community structure.\n \n \n \n \n\n\n \n Koizumi, S.; Hamdan, M.; Puts, I. C.; Bergström, A.; Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Freshwater Biology, 68(7): 1224–1237. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.14099\n\n\n\n
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\n\n\n@article{koizumi_experimental_2023,\n\ttitle = {Experimental warming and browning influence autumnal pelagic and benthic invertebrate biomass and community structure},\n\tvolume = {68},\n\tcopyright = {© 2023 The Authors. Freshwater Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2427},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.14099},\n\tdoi = {10.1111/fwb.14099},\n\tabstract = {Globally, lakes are warming and browning with ongoing climate change. These changes significantly impact a lake's biogeochemical properties and all organisms, including invertebrate consumers. The effects of these changes are essential to understand, especially during critical periods after and before the growing season, that is, autumn and spring, which can determine the composition of the invertebrate consumer community. In this study, we used a large-scale experimental pond system to test the combined effect of warming (+3°C) and increased input of terrestrial and coloured dissolved organic carbon (gradient of 1.6–8.8 mg/L in the ambient and 1.6–9.3 mg/L in the warm)—which causes browning—on zooplankton and benthic macroinvertebrate biomass and composition during the autumn and the following spring. Total zooplankton biomass decreased with warming and increased with browning, while total zoobenthos did not respond to either treatment. Warming and browning throughout the autumn had no overall interactive effects on zooplankton or zoobenthos. Autumnal warming decreased total pelagic consumer biomass, caused by a decrease in both Rotifera and Copepoda. In contrast, there was no effect on overall benthic consumer biomass, with only Asellus sp. biomass showing a negative response to warming. An autumnal increase in dissolved organic carbon led to increased total pelagic consumer biomass, which was related to increases in Daphnia sp. biomass but did not affect zoobenthos biomass. While we expected zooplankton and zoobenthos biomass to follow responses in primary and bacterial production to treatments, we did not find any relationship between consumer groups and these estimates of resource production. Our results suggest that consumer responses to warming and browning during autumn may lead to less overarching general changes in consumer biomass, and responses are mostly taxon-specific. This study gives novel insights into the effects of warming and browning on consumer biomass during autumn and spring and increases the understanding of the effects of climate change on invertebrate community biomass in the different habitats.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2023-07-20},\n\tjournal = {Freshwater Biology},\n\tauthor = {Koizumi, Shuntaro and Hamdan, Mohammed and Puts, Isolde Callisto and Bergström, Ann-Kristin and Karlsson, Jan and Byström, Pär},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.14099},\n\tkeywords = {\\#nosource, climate change, dissolved organic carbon, habitat-specific primary production, zoobenthos, zooplankton},\n\tpages = {1224--1237},\n}\n\n\n\n\n\n Globally, lakes are warming and browning with ongoing climate change. These changes significantly impact a lake's biogeochemical properties and all organisms, including invertebrate consumers. The effects of these changes are essential to understand, especially during critical periods after and before the growing season, that is, autumn and spring, which can determine the composition of the invertebrate consumer community. In this study, we used a large-scale experimental pond system to test the combined effect of warming (+3°C) and increased input of terrestrial and coloured dissolved organic carbon (gradient of 1.6–8.8 mg/L in the ambient and 1.6–9.3 mg/L in the warm)—which causes browning—on zooplankton and benthic macroinvertebrate biomass and composition during the autumn and the following spring. Total zooplankton biomass decreased with warming and increased with browning, while total zoobenthos did not respond to either treatment. Warming and browning throughout the autumn had no overall interactive effects on zooplankton or zoobenthos. Autumnal warming decreased total pelagic consumer biomass, caused by a decrease in both Rotifera and Copepoda. In contrast, there was no effect on overall benthic consumer biomass, with only Asellus sp. biomass showing a negative response to warming. An autumnal increase in dissolved organic carbon led to increased total pelagic consumer biomass, which was related to increases in Daphnia sp. biomass but did not affect zoobenthos biomass. While we expected zooplankton and zoobenthos biomass to follow responses in primary and bacterial production to treatments, we did not find any relationship between consumer groups and these estimates of resource production. Our results suggest that consumer responses to warming and browning during autumn may lead to less overarching general changes in consumer biomass, and responses are mostly taxon-specific. This study gives novel insights into the effects of warming and browning on consumer biomass during autumn and spring and increases the understanding of the effects of climate change on invertebrate community biomass in the different habitats.\n
\n\n\n\n \n\n \n \n \n \n \n \n Diel, seasonal, and inter-annual variation in carbon dioxide effluxes from lakes and reservoirs.\n \n \n \n \n\n\n \n Golub, M.; Koupaei-Abyazani, N.; Vesala, T.; Mammarella, I.; Ojala, A.; Bohrer, G.; Weyhenmeyer, G. A.; Blanken, P. D.; Eugster, W.; Koebsch, F.; Chen, J.; Czajkowski, K.; Deshmukh, C.; Guérin, F.; Heiskanen, J.; Humphreys, E.; Jonsson, A.; Karlsson, J.; Kling, G.; Lee, X.; Liu, H.; Lohila, A.; Lundin, E.; Morin, T.; Podgrajsek, E.; Provenzale, M.; Rutgersson, A.; Sachs, T.; Sahlée, E.; Serça, D.; Shao, C.; Spence, C.; Strachan, I. B.; Xiao, W.; and Desai, A. R.\n\n\n \n\n\n\n Environmental Research Letters, 18(3): 034046. March 2023.\n Publisher: IOP Publishing\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{golub_diel_2023,\n\ttitle = {Diel, seasonal, and inter-annual variation in carbon dioxide effluxes from lakes and reservoirs},\n\tvolume = {18},\n\tissn = {1748-9326},\n\turl = {https://dx.doi.org/10.1088/1748-9326/acb834},\n\tdoi = {10.1088/1748-9326/acb834},\n\tabstract = {Accounting for temporal changes in carbon dioxide (CO2) effluxes from freshwaters remains a challenge for global and regional carbon budgets. Here, we synthesize 171 site-months of flux measurements of CO2 based on the eddy covariance method from 13 lakes and reservoirs in the Northern Hemisphere, and quantify dynamics at multiple temporal scales. We found pronounced sub-annual variability in CO2 flux at all sites. By accounting for diel variation, only 11\\% of site-months were net daily sinks of CO2. Annual CO2 emissions had an average of 25\\% (range 3\\%–58\\%) interannual variation. Similar to studies on streams, nighttime emissions regularly exceeded daytime emissions. Biophysical regulations of CO2 flux variability were delineated through mutual information analysis. Sample analysis of CO2 fluxes indicate the importance of continuous measurements. Better characterization of short- and long-term variability is necessary to understand and improve detection of temporal changes of CO2 fluxes in response to natural and anthropogenic drivers. Our results indicate that existing global lake carbon budgets relying primarily on daytime measurements yield underestimates of net emissions.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2023-07-20},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Golub, Malgorzata and Koupaei-Abyazani, Nikaan and Vesala, Timo and Mammarella, Ivan and Ojala, Anne and Bohrer, Gil and Weyhenmeyer, Gesa A. and Blanken, Peter D. and Eugster, Werner and Koebsch, Franziska and Chen, Jiquan and Czajkowski, Kevin and Deshmukh, Chandrashekhar and Guérin, Frederic and Heiskanen, Jouni and Humphreys, Elyn and Jonsson, Anders and Karlsson, Jan and Kling, George and Lee, Xuhui and Liu, Heping and Lohila, Annalea and Lundin, Erik and Morin, Tim and Podgrajsek, Eva and Provenzale, Maria and Rutgersson, Anna and Sachs, Torsten and Sahlée, Erik and Serça, Dominique and Shao, Changliang and Spence, Christopher and Strachan, Ian B. and Xiao, Wei and Desai, Ankur R.},\n\tmonth = mar,\n\tyear = {2023},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {034046},\n}\n\n\n\n\n\n Accounting for temporal changes in carbon dioxide (CO2) effluxes from freshwaters remains a challenge for global and regional carbon budgets. Here, we synthesize 171 site-months of flux measurements of CO2 based on the eddy covariance method from 13 lakes and reservoirs in the Northern Hemisphere, and quantify dynamics at multiple temporal scales. We found pronounced sub-annual variability in CO2 flux at all sites. By accounting for diel variation, only 11% of site-months were net daily sinks of CO2. Annual CO2 emissions had an average of 25% (range 3%–58%) interannual variation. Similar to studies on streams, nighttime emissions regularly exceeded daytime emissions. Biophysical regulations of CO2 flux variability were delineated through mutual information analysis. Sample analysis of CO2 fluxes indicate the importance of continuous measurements. Better characterization of short- and long-term variability is necessary to understand and improve detection of temporal changes of CO2 fluxes in response to natural and anthropogenic drivers. Our results indicate that existing global lake carbon budgets relying primarily on daytime measurements yield underestimates of net emissions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Controls on Terrestrial Carbon Fluxes in Simulated Networks of Connected Streams and Lakes.\n \n \n \n \n\n\n \n Vachon, D.; Sponseller, R. A.; Rosvall, M.; and Karlsson, J.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 37(3): e2022GB007597. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GB007597\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{vachon_controls_2023,\n\ttitle = {Controls on {Terrestrial} {Carbon} {Fluxes} in {Simulated} {Networks} of {Connected} {Streams} and {Lakes}},\n\tvolume = {37},\n\tcopyright = {© 2023. The Authors.},\n\tissn = {1944-9224},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GB007597},\n\tdoi = {10.1029/2022GB007597},\n\tabstract = {Inland waters play a critical role in the carbon cycle by emitting significant amounts of land-exported carbon to the atmosphere. While carbon gas emissions from individual aquatic systems have been extensively studied, how networks of connected streams and lakes regulate integrated fluxes of organic and inorganic forms remain poorly understood. Here, we develop a process-based model to simulate the fate of terrestrial dissolved organic carbon (DOC) and carbon dioxide (CO2) in artificial inland water networks with variable topology, hydrology, and DOC reactivity. While the role of lakes is highly dependent on DOC reactivity, we find that the mineralization of terrestrial DOC is more efficient in lake-rich networks. Regardless of typology and hydrology, terrestrial CO2 is emitted almost entirely within the network boundary. Consequently, the proportion of exported terrestrial carbon emitted from inland water networks increases with the CO2 versus DOC export ratio. Overall, our results suggest that CO2 emissions from inland waters are governed by interactions between the relative amount and reactivity of terrestrial DOC and CO2 inputs and the network configuration of recipient lakes and streams.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2023-07-20},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Vachon, Dominic and Sponseller, Ryan A. and Rosvall, Martin and Karlsson, Jan},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GB007597},\n\tkeywords = {\\#nosource, CO2 emission, DOC mineralization, aquatic network, carbon cycle, modeling},\n\tpages = {e2022GB007597},\n}\n\n\n\n\n\n Inland waters play a critical role in the carbon cycle by emitting significant amounts of land-exported carbon to the atmosphere. While carbon gas emissions from individual aquatic systems have been extensively studied, how networks of connected streams and lakes regulate integrated fluxes of organic and inorganic forms remain poorly understood. Here, we develop a process-based model to simulate the fate of terrestrial dissolved organic carbon (DOC) and carbon dioxide (CO2) in artificial inland water networks with variable topology, hydrology, and DOC reactivity. While the role of lakes is highly dependent on DOC reactivity, we find that the mineralization of terrestrial DOC is more efficient in lake-rich networks. Regardless of typology and hydrology, terrestrial CO2 is emitted almost entirely within the network boundary. Consequently, the proportion of exported terrestrial carbon emitted from inland water networks increases with the CO2 versus DOC export ratio. Overall, our results suggest that CO2 emissions from inland waters are governed by interactions between the relative amount and reactivity of terrestrial DOC and CO2 inputs and the network configuration of recipient lakes and streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Integrating terrestrial and aquatic ecosystems to constrain estimates of land-atmosphere carbon exchange.\n \n \n \n \n\n\n \n Casas-Ruiz, J. P.; Bodmer, P.; Bona, K. A.; Butman, D.; Couturier, M.; Emilson, E. J. S.; Finlay, K.; Genet, H.; Hayes, D.; Karlsson, J.; Paré, D.; Peng, C.; Striegl, R.; Webb, J.; Wei, X.; Ziegler, S. E.; and del Giorgio, P. A.\n\n\n \n\n\n\n Nature Communications, 14(1): 1571. March 2023.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{casas-ruiz_integrating_2023,\n\ttitle = {Integrating terrestrial and aquatic ecosystems to constrain estimates of land-atmosphere carbon exchange},\n\tvolume = {14},\n\tcopyright = {2023 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-023-37232-2},\n\tdoi = {10.1038/s41467-023-37232-2},\n\tabstract = {In this Perspective, we put forward an integrative framework to improve estimates of land-atmosphere carbon exchange based on the accumulation of carbon in the landscape as constrained by its lateral export through rivers. The framework uses the watershed as the fundamental spatial unit and integrates all terrestrial and aquatic ecosystems as well as their hydrologic carbon exchanges. Application of the framework should help bridge the existing gap between land and atmosphere-based approaches and offers a platform to increase communication and synergy among the terrestrial, aquatic, and atmospheric research communities that is paramount to advance landscape carbon budget assessments.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2023-07-20},\n\tjournal = {Nature Communications},\n\tauthor = {Casas-Ruiz, Joan P. and Bodmer, Pascal and Bona, Kelly Ann and Butman, David and Couturier, Mathilde and Emilson, Erik J. S. and Finlay, Kerri and Genet, Hélène and Hayes, Daniel and Karlsson, Jan and Paré, David and Peng, Changhui and Striegl, Rob and Webb, Jackie and Wei, Xinyuan and Ziegler, Susan E. and del Giorgio, Paul A.},\n\tmonth = mar,\n\tyear = {2023},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource, Carbon cycle, Environmental sciences},\n\tpages = {1571},\n}\n\n\n\n\n\n In this Perspective, we put forward an integrative framework to improve estimates of land-atmosphere carbon exchange based on the accumulation of carbon in the landscape as constrained by its lateral export through rivers. The framework uses the watershed as the fundamental spatial unit and integrates all terrestrial and aquatic ecosystems as well as their hydrologic carbon exchanges. Application of the framework should help bridge the existing gap between land and atmosphere-based approaches and offers a platform to increase communication and synergy among the terrestrial, aquatic, and atmospheric research communities that is paramount to advance landscape carbon budget assessments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Nutrient limitation masks the dissolved organic matter composition effects on bacterial metabolism in unproductive freshwaters.\n \n \n \n \n\n\n \n Berggren, M.; Ye, L.; Sponseller, R. A.; Bergström, A.; Karlsson, J.; Verheijen, H.; and Hensgens, G.\n\n\n \n\n\n\n Limnology and Oceanography, n/a(n/a): 1–11. 2023.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12406\n\n\n\n
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\n\n\n@article{berggren_nutrient_2023,\n\ttitle = {Nutrient limitation masks the dissolved organic matter composition effects on bacterial metabolism in unproductive freshwaters},\n\tvolume = {n/a},\n\tcopyright = {© 2023 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.12406},\n\tdoi = {10.1002/lno.12406},\n\tabstract = {Aquatic microbial responses to changes in the amount and composition of dissolved organic carbon (DOC) are of fundamental ecological and biogeochemical importance. Parallel factor (PARAFAC) analysis of excitation–emission fluorescence spectra is a common tool to characterize DOC, yet its ability to predict bacterial production (BP), bacterial respiration (BR), and bacterial growth efficiency (BGE) vary widely, potentially because inorganic nutrient limitation decouples microbial processes from their dependence on DOC composition. We used 28-d bioassays with water from 19 lakes, streams, and rivers in northern Sweden to test how much the links between bacterial metabolism and fluorescence PARAFAC components depend on experimental additions of inorganic nutrients. We found a significant interaction effect between nutrient addition and fluorescence on carbon-specific BP, and weak evidence for influence on BGE by the same interaction (p = 0.1), but no corresponding interaction effect on BR. A practical implication of this interaction was that fluorescence components could explain more than twice as much of the variability in carbon-specific BP (R2 = 0.90) and BGE (R2 = 0.70) after nitrogen and phosphorus addition, compared with control incubations. Our results suggest that an increased supply of labile DOC relative to ambient phosphorus and nitrogen induces gradually larger degrees of nutrient limitation of BP, which in turn decouple BP and BGE from fluorescence signals. Thus, while fluorescence does contain precise information about the degree to which DOC can support microbial processes, this information may be hidden in field studies due to nutrient limitation of bacterial metabolism.},\n\tlanguage = {en},\n\tnumber = {n/a},\n\turldate = {2023-07-20},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Berggren, Martin and Ye, Linlin and Sponseller, Ryan A. and Bergström, Ann-Kristin and Karlsson, Jan and Verheijen, Hendricus and Hensgens, Geert},\n\tyear = {2023},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12406},\n\tkeywords = {\\#nosource, ⛔ No INSPIRE recid found},\n\tpages = {1--11},\n}\n\n\n\n\n\n Aquatic microbial responses to changes in the amount and composition of dissolved organic carbon (DOC) are of fundamental ecological and biogeochemical importance. Parallel factor (PARAFAC) analysis of excitation–emission fluorescence spectra is a common tool to characterize DOC, yet its ability to predict bacterial production (BP), bacterial respiration (BR), and bacterial growth efficiency (BGE) vary widely, potentially because inorganic nutrient limitation decouples microbial processes from their dependence on DOC composition. We used 28-d bioassays with water from 19 lakes, streams, and rivers in northern Sweden to test how much the links between bacterial metabolism and fluorescence PARAFAC components depend on experimental additions of inorganic nutrients. We found a significant interaction effect between nutrient addition and fluorescence on carbon-specific BP, and weak evidence for influence on BGE by the same interaction (p = 0.1), but no corresponding interaction effect on BR. A practical implication of this interaction was that fluorescence components could explain more than twice as much of the variability in carbon-specific BP (R2 = 0.90) and BGE (R2 = 0.70) after nitrogen and phosphorus addition, compared with control incubations. Our results suggest that an increased supply of labile DOC relative to ambient phosphorus and nitrogen induces gradually larger degrees of nutrient limitation of BP, which in turn decouple BP and BGE from fluorescence signals. Thus, while fluorescence does contain precise information about the degree to which DOC can support microbial processes, this information may be hidden in field studies due to nutrient limitation of bacterial metabolism.\n
\n\n\n\n \n\n \n \n \n \n \n Environmental controllers for carbon emission and concentration patterns in Siberian rivers during different seasons.\n \n \n \n\n\n \n Krickov, I. V.; Lim, A. G.; Shirokova, L. S.; Korets, M.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Science of The Total Environment, 859: 160202. February 2023.\n Publisher: Elsevier\n\n\n\n
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\n\n\n@article{krickov_environmental_2023,\n\ttitle = {Environmental controllers for carbon emission and concentration patterns in {Siberian} rivers during different seasons},\n\tvolume = {859},\n\tissn = {0048-9697},\n\tdoi = {10.1016/J.SCITOTENV.2022.160202},\n\tabstract = {Despite the importance of small and medium size rivers of Siberian boreal zone in greenhouse gases (GHG) emission, major knowledge gaps exist regarding its temporal variability and controlling mechanisms. Here we sampled 11 pristine rivers of the southern taiga biome (western Siberia Lowland, WSL), ranging in watershed area from 0.8 to 119,000 km2, to reveal temporal pattern and examine main environmental controllers of GHG emissions from the river water surfaces. Floating chamber measurements demonstrated that CO2 emissions from water surface decreased by 2 to 4-folds from spring to summer and autumn, were independent of the size of the watershed and stream order and did not exhibit sizable ({\\textgreater}30 \\%, regardless of season) variations between day and night. The CH4 concentrations and fluxes increased in the order “spring ≤ summer {\\textless} autumn” and ranged from 1 to 15 μmol L−1 and 5 to 100 mmol m−2 d−1, respectively. The CO2 concentrations and fluxes (range from 100 to 400 μmol L−1 and 1 to 4 g C m−2 d−1, respectively) were positively correlated with dissolved and particulate organic carbon, total nitrogen and bacterial number of the water column. The CH4 concentrations and fluxes were positively correlated with phosphate and ammonia concentrations. Of the landscape parameters, positive correlations were detected between riparian vegetation biomass and CO2 and CH4 concentrations. Over the six-month open-water period, areal emissions of C ({\\textgreater}99.5 \\% CO2; {\\textless}0.5 \\% CH4) from the watersheds of 11 rivers were equal to the total downstream C export in this part of the WSL. Based on correlations between environmental controllers (watershed land cover and the water column parameters), we hypothesize that the fluxes are largely driven by riverine mineralization of terrestrial dissolved and particulate OC, coupled with respiration at the river bottom and riparian sediments. It follows that, under climate warming scenario, most significant changes in GHG regimes of western Siberian rivers located in permafrost-free zone may occur due to changes in the riparian zone vegetation and water coverage of the floodplains.},\n\turldate = {2023-07-20},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Krickov, Ivan V. and Lim, Artem G. and Shirokova, Liudmila S. and Korets, Mikhail and Karlsson, Jan and Pokrovsky, Oleg S.},\n\tmonth = feb,\n\tyear = {2023},\n\tpmid = {36395838},\n\tnote = {Publisher: Elsevier},\n\tkeywords = {\\#nosource, Boreal, CH4, CO2, Emission, Landscape, Organic carbon, River},\n\tpages = {160202},\n}\n\n\n\n\n\n Despite the importance of small and medium size rivers of Siberian boreal zone in greenhouse gases (GHG) emission, major knowledge gaps exist regarding its temporal variability and controlling mechanisms. Here we sampled 11 pristine rivers of the southern taiga biome (western Siberia Lowland, WSL), ranging in watershed area from 0.8 to 119,000 km2, to reveal temporal pattern and examine main environmental controllers of GHG emissions from the river water surfaces. Floating chamber measurements demonstrated that CO2 emissions from water surface decreased by 2 to 4-folds from spring to summer and autumn, were independent of the size of the watershed and stream order and did not exhibit sizable (\\textgreater30 %, regardless of season) variations between day and night. The CH4 concentrations and fluxes increased in the order “spring ≤ summer \\textless autumn” and ranged from 1 to 15 μmol L−1 and 5 to 100 mmol m−2 d−1, respectively. The CO2 concentrations and fluxes (range from 100 to 400 μmol L−1 and 1 to 4 g C m−2 d−1, respectively) were positively correlated with dissolved and particulate organic carbon, total nitrogen and bacterial number of the water column. The CH4 concentrations and fluxes were positively correlated with phosphate and ammonia concentrations. Of the landscape parameters, positive correlations were detected between riparian vegetation biomass and CO2 and CH4 concentrations. Over the six-month open-water period, areal emissions of C (\\textgreater99.5 % CO2; \\textless0.5 % CH4) from the watersheds of 11 rivers were equal to the total downstream C export in this part of the WSL. Based on correlations between environmental controllers (watershed land cover and the water column parameters), we hypothesize that the fluxes are largely driven by riverine mineralization of terrestrial dissolved and particulate OC, coupled with respiration at the river bottom and riparian sediments. It follows that, under climate warming scenario, most significant changes in GHG regimes of western Siberian rivers located in permafrost-free zone may occur due to changes in the riparian zone vegetation and water coverage of the floodplains.\n
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\n \n \n\n \n \n \n \n \n \n Can bryophyte groups increase functional resolution in tundra ecosystems?.\n \n \n \n \n\n\n \n Lett, S.; Jónsdóttir, I. S.; Becker-Scarpitta, A.; Christiansen, C. T.; During, H.; Ekelund, F.; Henry, G. H.; Lang, S. I.; Michelsen, A.; Rousk, K.; Alatalo, J. M.; Betway, K. R.; Rui, S. B.; Callaghan, T.; Carbognani, M.; Cooper, E. J.; Cornelissen, J. H. C.; Dorrepaal, E.; Egelkraut, D.; Elumeeva, T. G.; Haugum, S. V.; Hollister, R. D.; Jägerbrand, A. K.; Keuper, F.; Klanderud, K.; Lévesque, E.; Liu, X.; May, J.; Michel, P.; Mörsdorf, M.; Petraglia, A.; Rixen, C.; Robroek, B. J.; Rzepczynska, A. M.; Soudzilovskaia, N. A.; Tolvanen, A.; Vandvik, V.; Volkov, I.; Volkova, I.; and Zuijlen, K. v.\n\n\n \n\n\n\n Arctic Science, 8(3): 609–637. September 2022.\n Publisher: NRC Research Press\n\n\n\n
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\n\n\n@article{lett_can_2022,\n\ttitle = {Can bryophyte groups increase functional resolution in tundra ecosystems?},\n\tvolume = {8},\n\turl = {https://cdnsciencepub.com/doi/full/10.1139/as-2020-0057},\n\tdoi = {10.1139/as-2020-0057},\n\tabstract = {The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Arctic Science},\n\tauthor = {Lett, Signe and Jónsdóttir, Ingibjörg S. and Becker-Scarpitta, Antoine and Christiansen, Casper T. and During, Heinjo and Ekelund, Flemming and Henry, Gregory H.R. and Lang, Simone I. and Michelsen, Anders and Rousk, Kathrin and Alatalo, Juha M. and Betway, Katlyn R. and Rui, Sara B. and Callaghan, Terry and Carbognani, Michele and Cooper, Elisabeth J. and Cornelissen, J. Hans C. and Dorrepaal, Ellen and Egelkraut, Dagmar and Elumeeva, Tatiana G. and Haugum, Siri V. and Hollister, Robert D. and Jägerbrand, Annika K. and Keuper, Frida and Klanderud, Kari and Lévesque, Esther and Liu, Xin and May, Jeremy and Michel, Pascale and Mörsdorf, Martin and Petraglia, Alessandro and Rixen, Christian and Robroek, Bjorn J.M. and Rzepczynska, Agnieszka M. and Soudzilovskaia, Nadejda A. and Tolvanen, Anne and Vandvik, Vigdis and Volkov, Igor and Volkova, Irina and Zuijlen, Kristel van},\n\tmonth = sep,\n\tyear = {2022},\n\tnote = {Publisher: NRC Research Press},\n\tkeywords = {\\#nosource},\n\tpages = {609--637},\n}\n\n\n\n\n\n The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.\n
\n\n\n\n \n\n \n \n \n \n \n \n Large herbivores on permafrost— a pilot study of grazing impacts on permafrost soil carbon storage in northeastern Siberia.\n \n \n \n \n\n\n \n Windirsch, T.; Grosse, G.; Ulrich, M.; Forbes, B. C.; Göckede, M.; Wolter, J.; Macias-Fauria, M.; Olofsson, J.; Zimov, N.; and Strauss, J.\n\n\n \n\n\n\n Frontiers in Environmental Science, 10: 893478. August 2022.\n Publisher: Frontiers\n\n\n\n
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\n\n\n@article{windirsch_large_2022,\n\ttitle = {Large herbivores on permafrost— a pilot study of grazing impacts on permafrost soil carbon storage in northeastern {Siberia}},\n\tvolume = {10},\n\tissn = {2296-665X},\n\turl = {https://www.frontiersin.org/articles/10.3389/fenvs.2022.893478},\n\tdoi = {10.3389/fenvs.2022.893478},\n\tabstract = {The risk of carbon emissions from permafrost is linked to an increase in ground temperature and thus in particular to thermal insulation by vegetation, soil layers and snow cover. Ground insulation can be influenced by the presence of large herbivores browsing for food in both winter and summer. In this study, we examine the potential impact of large herbivore presence on the soil carbon storage in a thermokarst landscape in northeastern Siberia. Our aim in this pilot study is to conduct a first analysis on whether intensive large herbivore grazing may slow or even reverse permafrost thaw by affecting thermal insulation through modifying ground cover properties. As permafrost soil temperatures are important for organic matter decomposition, we hypothesize that herbivory disturbances lead to different ground carbon storages. Therefore, we analyzed five sites with a total of three different herbivore grazing intensities on two landscape forms (drained thermokarst basin, Yedoma upland) in Pleistocene Park near Chersky. We measured maximum thaw depth, total organic carbon content,δ13C isotopes , carbon-nitrogen ratios, and sediment grain-size composition as well as ice and water content for each site. We found the thaw depth to be shallower and carbon storage to be higher in intensively grazed areas compared to extensively and non-grazed sites in the same thermokarst basin. First data show that intensive grazing leads to a more stable thermal ground regime and thus to increased carbon storage in the thermokarst deposits and active layer. However, the high carbon content found within the upper 20 cm on intensively grazed sites could also indicate higher carbon input rather than reduced decomposition, which requires further studies including investigations of the hydrology and general ground conditions existing prior to grazing introduction. We explain our findings by intensive animal trampling in winter and vegetation changes, which overcompensate summer ground warming. We conclude that grazing intensity – along with soil substrate and hydrologic conditions – might have a measurable influence on the carbon storage in permafrost soils. Hence the grazing effect should be further investigated for its potential as an actively manageable instrument to reduce net carbon emission from permafrost.},\n\tlanguage = {English},\n\turldate = {2024-03-27},\n\tjournal = {Frontiers in Environmental Science},\n\tauthor = {Windirsch, Torben and Grosse, Guido and Ulrich, Mathias and Forbes, Bruce C. and Göckede, Mathias and Wolter, Juliane and Macias-Fauria, Marc and Olofsson, Johan and Zimov, Nikita and Strauss, Jens},\n\tmonth = aug,\n\tyear = {2022},\n\tnote = {Publisher: Frontiers},\n\tkeywords = {Animal Husbandry, Climate Change, bio-geo interactions, organic material inventory, rewilding},\n\tpages = {893478},\n}\n\n\n\n\n\n The risk of carbon emissions from permafrost is linked to an increase in ground temperature and thus in particular to thermal insulation by vegetation, soil layers and snow cover. Ground insulation can be influenced by the presence of large herbivores browsing for food in both winter and summer. In this study, we examine the potential impact of large herbivore presence on the soil carbon storage in a thermokarst landscape in northeastern Siberia. Our aim in this pilot study is to conduct a first analysis on whether intensive large herbivore grazing may slow or even reverse permafrost thaw by affecting thermal insulation through modifying ground cover properties. As permafrost soil temperatures are important for organic matter decomposition, we hypothesize that herbivory disturbances lead to different ground carbon storages. Therefore, we analyzed five sites with a total of three different herbivore grazing intensities on two landscape forms (drained thermokarst basin, Yedoma upland) in Pleistocene Park near Chersky. We measured maximum thaw depth, total organic carbon content,δ13C isotopes , carbon-nitrogen ratios, and sediment grain-size composition as well as ice and water content for each site. We found the thaw depth to be shallower and carbon storage to be higher in intensively grazed areas compared to extensively and non-grazed sites in the same thermokarst basin. First data show that intensive grazing leads to a more stable thermal ground regime and thus to increased carbon storage in the thermokarst deposits and active layer. However, the high carbon content found within the upper 20 cm on intensively grazed sites could also indicate higher carbon input rather than reduced decomposition, which requires further studies including investigations of the hydrology and general ground conditions existing prior to grazing introduction. We explain our findings by intensive animal trampling in winter and vegetation changes, which overcompensate summer ground warming. We conclude that grazing intensity – along with soil substrate and hydrologic conditions – might have a measurable influence on the carbon storage in permafrost soils. Hence the grazing effect should be further investigated for its potential as an actively manageable instrument to reduce net carbon emission from permafrost.\n
\n\n\n\n \n\n \n \n \n \n \n \n Responses of multiple structural and functional indicators along three contrasting disturbance gradients.\n \n \n \n \n\n\n \n Truchy, A.; Sponseller, R. A.; Ecke, F.; Angeler, D. G.; Kahlert, M.; Bundschuh, M.; Johnson, R. K.; and McKie, B. G.\n\n\n \n\n\n\n Ecological Indicators, 135: 108514. February 2022.\n \n\n\n\n
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\n\n\n@article{truchy_responses_2022,\n\ttitle = {Responses of multiple structural and functional indicators along three contrasting disturbance gradients},\n\tvolume = {135},\n\tissn = {1470-160X},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1470160X21011791},\n\tdoi = {10.1016/j.ecolind.2021.108514},\n\tabstract = {Ecosystem functioning and community structure are recognized as key components of ecosystem integrity, but comprehensive, standardized studies of the responses of both structural and functional indicators to different types of anthropogenic pressures remain rare. Consequently, we lack an empirical basis for (i) identifying when monitoring ecosystem structure alone misses important changes in ecosystem functioning, (ii) recommending sets of structural and functional metrics best suited for detecting ecological change driven by different anthropogenic pressures, and (iii) understanding the cumulative effects of multiple, co-occurring stressors on structure and function. We investigated variation in community structure and ecosystem functioning of stream ecosystems along three gradients (10–16 independent stream sites each) of increasing impact arising from agriculture, forestry and river regulation for hydropower, respectively. For each stream, we quantified variation in (i) the abiotic environment, (ii) community composition of four organism groups and (iii) three basal ecosystem processes underpinning carbon and nutrient cycling in streams. We assessed the responsiveness of multiple biodiversity, community structure and ecosystem functioning indicators based on variance explained and effect size metrics. Along a gradient of increasing agricultural impact, diatoms and fish were the most responsive groups overall, but significant variation was detected in at least one aspect of community composition, abundance and/or biodiversity of every organism group . In contrast, most of our functional metrics did not vary significantly along the agricultural gradient, possibly due to contrasting, antagonistic effects of increasing nutrient concentrations and turbidity on ecosystem process rates. The exception was detritivore-mediated litter decomposition which increased up to moderate levels of nutrient. Impacts of river regulation were most marked for diatoms, which were responsive to both increasingly frequent hydropeaking and to increasing seasonal river regulation. Among functional indicators, both litter decomposition and algal biomass accrual declined significantly with increasing hydropeaking. Few structural or functional metrics varied with forest management, with macroinvertebrate diversity increasing along the forestry gradient, as did algal and fungal biomass accrual. Together, these findings highlight the challenges of making inferences about the impacts of anthropogenic disturbances at the ecosystem level based on community data alone, and pinpoint the need to identify optimal sets of functional and structural indicators best suited for detecting ecological changes associated with different human activities.},\n\turldate = {2024-03-27},\n\tjournal = {Ecological Indicators},\n\tauthor = {Truchy, Amélie and Sponseller, Ryan A. and Ecke, Frauke and Angeler, David G. and Kahlert, Maria and Bundschuh, Mirco and Johnson, Richard K. and McKie, Brendan G.},\n\tmonth = feb,\n\tyear = {2022},\n\tkeywords = {Agriculture, Community structure, Ecosystem functioning, Forestry, Multiple stressors, River regulation},\n\tpages = {108514},\n}\n\n\n\n\n\n Ecosystem functioning and community structure are recognized as key components of ecosystem integrity, but comprehensive, standardized studies of the responses of both structural and functional indicators to different types of anthropogenic pressures remain rare. Consequently, we lack an empirical basis for (i) identifying when monitoring ecosystem structure alone misses important changes in ecosystem functioning, (ii) recommending sets of structural and functional metrics best suited for detecting ecological change driven by different anthropogenic pressures, and (iii) understanding the cumulative effects of multiple, co-occurring stressors on structure and function. We investigated variation in community structure and ecosystem functioning of stream ecosystems along three gradients (10–16 independent stream sites each) of increasing impact arising from agriculture, forestry and river regulation for hydropower, respectively. For each stream, we quantified variation in (i) the abiotic environment, (ii) community composition of four organism groups and (iii) three basal ecosystem processes underpinning carbon and nutrient cycling in streams. We assessed the responsiveness of multiple biodiversity, community structure and ecosystem functioning indicators based on variance explained and effect size metrics. Along a gradient of increasing agricultural impact, diatoms and fish were the most responsive groups overall, but significant variation was detected in at least one aspect of community composition, abundance and/or biodiversity of every organism group . In contrast, most of our functional metrics did not vary significantly along the agricultural gradient, possibly due to contrasting, antagonistic effects of increasing nutrient concentrations and turbidity on ecosystem process rates. The exception was detritivore-mediated litter decomposition which increased up to moderate levels of nutrient. Impacts of river regulation were most marked for diatoms, which were responsive to both increasingly frequent hydropeaking and to increasing seasonal river regulation. Among functional indicators, both litter decomposition and algal biomass accrual declined significantly with increasing hydropeaking. Few structural or functional metrics varied with forest management, with macroinvertebrate diversity increasing along the forestry gradient, as did algal and fungal biomass accrual. Together, these findings highlight the challenges of making inferences about the impacts of anthropogenic disturbances at the ecosystem level based on community data alone, and pinpoint the need to identify optimal sets of functional and structural indicators best suited for detecting ecological changes associated with different human activities.\n
\n\n\n\n \n\n \n \n \n \n \n \n The emerging role of drought as a regulator of dissolved organic carbon in boreal landscapes.\n \n \n \n \n\n\n \n Tiwari, T.; Sponseller, R. A.; and Laudon, H.\n\n\n \n\n\n\n Nature Communications, 13(1): 5125. August 2022.\n Publisher: Nature Publishing Group\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{tiwari_emerging_2022,\n\ttitle = {The emerging role of drought as a regulator of dissolved organic carbon in boreal landscapes},\n\tvolume = {13},\n\tcopyright = {2022 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-022-32839-3},\n\tdoi = {10.1038/s41467-022-32839-3},\n\tabstract = {One likely consequence of global climate change is an increased frequency and intensity of droughts at high latitudes. Here we use a 17-year record from 13 nested boreal streams to examine direct and lagged effects of summer drought on the quantity and quality of dissolved organic carbon (DOC) inputs from catchment soils. Protracted periods of drought reduced DOC concentrations in all catchments but also led to large stream DOC pulses upon rewetting. Concurrent changes in DOC optical properties and chemical character suggest that seasonal drying and rewetting trigger soil processes that alter the forms of carbon supplied to streams. Contrary to expectations, clearest drought effects were observed in larger watersheds, whereas responses were most muted in smaller, peatland-dominated catchments. Collectively, our results indicate that summer drought causes a fundamental shift in the seasonal distribution of DOC concentrations and character, which together operate as primary controls over the ecological and biogeochemical functioning of northern aquatic ecosystems.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Nature Communications},\n\tauthor = {Tiwari, Tejshree and Sponseller, Ryan A. and Laudon, Hjalmar},\n\tmonth = aug,\n\tyear = {2022},\n\tnote = {Publisher: Nature Publishing Group},\n\tkeywords = {Carbon cycle, Environmental impact, Hydrology},\n\tpages = {5125},\n}\n\n\n\n\n\n One likely consequence of global climate change is an increased frequency and intensity of droughts at high latitudes. Here we use a 17-year record from 13 nested boreal streams to examine direct and lagged effects of summer drought on the quantity and quality of dissolved organic carbon (DOC) inputs from catchment soils. Protracted periods of drought reduced DOC concentrations in all catchments but also led to large stream DOC pulses upon rewetting. Concurrent changes in DOC optical properties and chemical character suggest that seasonal drying and rewetting trigger soil processes that alter the forms of carbon supplied to streams. Contrary to expectations, clearest drought effects were observed in larger watersheds, whereas responses were most muted in smaller, peatland-dominated catchments. Collectively, our results indicate that summer drought causes a fundamental shift in the seasonal distribution of DOC concentrations and character, which together operate as primary controls over the ecological and biogeochemical functioning of northern aquatic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Predicting the structure and functions of peatland microbial communities from Sphagnum phylogeny, anatomical and morphological traits and metabolites.\n \n \n \n \n\n\n \n Sytiuk, A.; Céréghino, R.; Hamard, S.; Delarue, F.; Guittet, A.; Barel, J. M.; Dorrepaal, E.; Küttim, M.; Lamentowicz, M.; Pourrut, B.; Robroek, B. J. M.; Tuittila, E.; and Jassey, V. E. J.\n\n\n \n\n\n\n Journal of Ecology, 110(1): 80–96. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.13728\n\n\n\n
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\n\n\n@article{sytiuk_predicting_2022,\n\ttitle = {Predicting the structure and functions of peatland microbial communities from {Sphagnum} phylogeny, anatomical and morphological traits and metabolites},\n\tvolume = {110},\n\tcopyright = {© 2021 British Ecological Society},\n\tissn = {1365-2745},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.13728},\n\tdoi = {10.1111/1365-2745.13728},\n\tabstract = {Sphagnum mosses are keystone species in northern peatlands. Notably, they play an important role in peatland carbon (C) cycling by regulating the composition and activity of microbial communities. However, it remains unclear whether information on Sphagnum phylogeny and/or traits-based composition (i.e. anatomical and morphological traits and metabolites) can be used to predict the structure of microbial communities and their functioning. Here we evaluated whether Sphagnum phylogeny and traits predict additional variation in peatland microbial community composition and functioning beyond what would be predicted from environmental characteristics (i.e. climatic and edaphic conditions). We collected Sphagnum and microbial data from five European peatlands distributed along a latitudinal gradient from northern Sweden to southern France. These data allowed us to assess Sphagnum anatomical and morphological traits and metabolites at different sites along changing environmental conditions. Using structural equation modelling (SEM) and phylogenetic distance analyses, we investigated the role of Sphagnum traits in shaping microbial community composition and functioning along with environmental conditions. We show that microbial community composition and traits varied independently from both Sphagnum phylogeny and the latitudinal gradient. Specifically, the addition of Sphagnum traits to climatic and edaphic variables to the SEM allowed it to explain a larger proportion of the explained variance (R2). This observation was most apparent for the biomass of decomposers (+42\\%) and phototrophs (+19\\%), as well as for growth yield microbial traits (+10\\%). As such, that Sphagnum metabolites were important drivers for microbial community structure and traits, while Sphagnum anatomical and morphological traits were poor predictors. Synthesis. Our results highlight that Sphagnum metabolites are more likely to influence peatland microbial food web structure and functioning than Sphagnum anatomical and morphological traits. We provide further evidence that measurements of the plant metabolome, when combined with classical functional traits, improve our understanding of how the plants interact with their associated microbiomes.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {Sytiuk, Anna and Céréghino, Régis and Hamard, Samuel and Delarue, Frédéric and Guittet, Amélie and Barel, Janna M. and Dorrepaal, Ellen and Küttim, Martin and Lamentowicz, Mariusz and Pourrut, Bertrand and Robroek, Bjorn J. M. and Tuittila, Eeva-Stiina and Jassey, Vincent E. J.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.13728},\n\tkeywords = {\\#nosource, Sphagnum, functional traits, latitudinal gradient, metabolomics, microbial traits, peatlands, plant and microbial communities, plant–soil (below-ground) interactions},\n\tpages = {80--96},\n}\n\n\n\n\n\n Sphagnum mosses are keystone species in northern peatlands. Notably, they play an important role in peatland carbon (C) cycling by regulating the composition and activity of microbial communities. However, it remains unclear whether information on Sphagnum phylogeny and/or traits-based composition (i.e. anatomical and morphological traits and metabolites) can be used to predict the structure of microbial communities and their functioning. Here we evaluated whether Sphagnum phylogeny and traits predict additional variation in peatland microbial community composition and functioning beyond what would be predicted from environmental characteristics (i.e. climatic and edaphic conditions). We collected Sphagnum and microbial data from five European peatlands distributed along a latitudinal gradient from northern Sweden to southern France. These data allowed us to assess Sphagnum anatomical and morphological traits and metabolites at different sites along changing environmental conditions. Using structural equation modelling (SEM) and phylogenetic distance analyses, we investigated the role of Sphagnum traits in shaping microbial community composition and functioning along with environmental conditions. We show that microbial community composition and traits varied independently from both Sphagnum phylogeny and the latitudinal gradient. Specifically, the addition of Sphagnum traits to climatic and edaphic variables to the SEM allowed it to explain a larger proportion of the explained variance (R2). This observation was most apparent for the biomass of decomposers (+42%) and phototrophs (+19%), as well as for growth yield microbial traits (+10%). As such, that Sphagnum metabolites were important drivers for microbial community structure and traits, while Sphagnum anatomical and morphological traits were poor predictors. Synthesis. Our results highlight that Sphagnum metabolites are more likely to influence peatland microbial food web structure and functioning than Sphagnum anatomical and morphological traits. We provide further evidence that measurements of the plant metabolome, when combined with classical functional traits, improve our understanding of how the plants interact with their associated microbiomes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Problems With the Shoreline Development Index—A Widely Used Metric of Lake Shape.\n \n \n \n \n\n\n \n Seekell, D.; Cael, B. B.; and Byström, P.\n\n\n \n\n\n\n Geophysical Research Letters, 49(10): e2022GL098499. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GL098499\n\n\n\n
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\n\n\n@article{seekell_problems_2022,\n\ttitle = {Problems {With} the {Shoreline} {Development} {Index}—{A} {Widely} {Used} {Metric} of {Lake} {Shape}},\n\tvolume = {49},\n\tcopyright = {© 2022. The Authors.},\n\tissn = {1944-8007},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GL098499},\n\tdoi = {10.1029/2022GL098499},\n\tabstract = {The shoreline development index—The ratio of a lake’s shore length to the circumference of a circle with the lake’s area—Is a core metric of lake morphometry used in Earth and planetary sciences. In this paper, we demonstrate that the shoreline development index is scale-dependent and cannot be used to compare lakes with different areas. We show that large lakes will have higher shoreline development index measurements than smaller lakes of the same characteristic shape, even when mapped at the same scale. Specifically, the shoreline development index increases by about 14\\% for each doubling of lake area. These results call into question previously reported patterns of lake shape. We provide several suggestions to improve the application of this index, including a bias-corrected formulation for comparing lakes with different surface areas.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2024-03-27},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Seekell, D. and Cael, B. B. and Byström, P.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GL098499},\n\tkeywords = {lake morphometry, scale-dependence, shoreline development index},\n\tpages = {e2022GL098499},\n}\n\n\n\n\n\n The shoreline development index—The ratio of a lake’s shore length to the circumference of a circle with the lake’s area—Is a core metric of lake morphometry used in Earth and planetary sciences. In this paper, we demonstrate that the shoreline development index is scale-dependent and cannot be used to compare lakes with different areas. We show that large lakes will have higher shoreline development index measurements than smaller lakes of the same characteristic shape, even when mapped at the same scale. Specifically, the shoreline development index increases by about 14% for each doubling of lake area. These results call into question previously reported patterns of lake shape. We provide several suggestions to improve the application of this index, including a bias-corrected formulation for comparing lakes with different surface areas.\n
\n\n\n\n \n\n \n \n \n \n \n \n Species traits interact with stress level to determine intraspecific facilitation and competition.\n \n \n \n \n\n\n \n Sarneel, J. M.; Hefting, M. M.; Visser, E. J. W.; Díaz-Sierra, R.; Voesenek, L. A. C. J.; and Kowalchuk, G. A.\n\n\n \n\n\n\n Journal of Vegetation Science, 33(5): e13145. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.13145\n\n\n\n
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\n\n\n@article{sarneel_species_2022,\n\ttitle = {Species traits interact with stress level to determine intraspecific facilitation and competition},\n\tvolume = {33},\n\tcopyright = {© 2022 The Authors. Journal of Vegetation Science published by John Wiley \\& Sons Ltd on behalf of International Association for Vegetation Science.},\n\tissn = {1654-1103},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.13145},\n\tdoi = {10.1111/jvs.13145},\n\tabstract = {Questions Flooding and drought stress are expected to increase significantly across the world and plant responses to these abiotic changes may be mediated by plant–plant interactions. Stress tolerance and recovery often require a biomass investment that may have consequences for these plant–plant interactions. Therefore, we questioned whether phenotypic plasticity in response to flooding and drought affected the balance between competition and facilitation for species with specific adaptations to drought or flooding. Location Utrecht University. Methods Stem elongation, root porosity, root:shoot ratio and biomass production were measured for six species during drought, well-drained and submerged conditions when grown alone or together with conspecifics. We quantified competition and facilitation as the ‘neighbour intensity effect’ directly after the 10-day treatment and again after a seven-day recovery period in well-drained conditions. Results Water stress, planting density and species identity interactively affected standardized stem elongation in a way that could lead to facilitation during submergence for species that preferably grow in wet soils. Root porosity was affected by the interaction between neighbour presence and time-step. Plant traits were only slightly affected during drought. The calculated neighbour interaction effect indicated facilitation for wetland species during submerged conditions and, after a period to recover from flooding, for species that prefer dry habitats. Conclusions Our results imply that changing plant–plant interactions in response to submergence and to a lesser extent to drought should be considered when predicting vegetation dynamics due to changing hydroclimatic regimes. Moreover, facilitation during a recovery period may enable species maladapted to flooding to persist.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Sarneel, Judith M. and Hefting, Mariet M. and Visser, Eric J. W. and Díaz-Sierra, Rubén and Voesenek, Laurentius A. C. J. and Kowalchuk, George A.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.13145},\n\tkeywords = {neighbour intensity effect, plant–plant interactions, recovery period, riparian vegetation, stress gradient hypothesis, water stress},\n\tpages = {e13145},\n}\n\n\n\n\n\n Questions Flooding and drought stress are expected to increase significantly across the world and plant responses to these abiotic changes may be mediated by plant–plant interactions. Stress tolerance and recovery often require a biomass investment that may have consequences for these plant–plant interactions. Therefore, we questioned whether phenotypic plasticity in response to flooding and drought affected the balance between competition and facilitation for species with specific adaptations to drought or flooding. Location Utrecht University. Methods Stem elongation, root porosity, root:shoot ratio and biomass production were measured for six species during drought, well-drained and submerged conditions when grown alone or together with conspecifics. We quantified competition and facilitation as the ‘neighbour intensity effect’ directly after the 10-day treatment and again after a seven-day recovery period in well-drained conditions. Results Water stress, planting density and species identity interactively affected standardized stem elongation in a way that could lead to facilitation during submergence for species that preferably grow in wet soils. Root porosity was affected by the interaction between neighbour presence and time-step. Plant traits were only slightly affected during drought. The calculated neighbour interaction effect indicated facilitation for wetland species during submerged conditions and, after a period to recover from flooding, for species that prefer dry habitats. Conclusions Our results imply that changing plant–plant interactions in response to submergence and to a lesser extent to drought should be considered when predicting vegetation dynamics due to changing hydroclimatic regimes. Moreover, facilitation during a recovery period may enable species maladapted to flooding to persist.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal patterns in nutrient bioavailability in boreal headwater streams.\n \n \n \n \n\n\n \n Rulli, M. P. D.; Bergström, A.; Sponseller, R. A.; and Berggren, M.\n\n\n \n\n\n\n Limnology and Oceanography, 67(5): 1169–1183. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12064\n\n\n\n
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\n\n\n@article{rulli_seasonal_2022,\n\ttitle = {Seasonal patterns in nutrient bioavailability in boreal headwater streams},\n\tvolume = {67},\n\tcopyright = {© 2022 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.12064},\n\tdoi = {10.1002/lno.12064},\n\tabstract = {Changes in nutrient bioavailability due to increased loading of dissolved organic matter (DOM) may impact boreal freshwaters. Yet, the relative bioavailability of carbon (C), nitrogen (N), and phosphorus (P) associated with terrestrial DOM remains poorly understood. We applied short-term bioassays with natural bacterial inocula to determine seasonal variation in bioavailable organic nutrient pools from four boreal headwater streams in northern Sweden. Experiments were designed to exhaust bioavailable nutrients associated with DOM by inducing limiting conditions when all required resources except for the targeted nutrient (C, N, or P) are provided in excess. We hypothesized that the supply of different bioavailable nutrients to streams would reflect seasonal variations in terrestrial demand, hydrology, and temperature. The delivery of bioavailable DOM-associated resources from the four streams were, on average, 2\\%, 11\\%, and 38\\% of the total dissolved organic C, N, and P, respectively, emphasizing the relatively low C bioavailability in these DOM-rich waters. Bioavailable N : P ratios peaked in autumn for all sites, with lower values in winter and spring. Both in terms of relative (\\% of total) and absolute bioavailable organic nutrient concentrations, the seasonal pattern was characterized by systematically high values for the autumn period. Furthermore, links between bioavailable resources and temperature and hydrology varied across sites, time periods, and the different elements. Thus, elevated concentrations of bioavailable organic resources in autumn suggest the potential for leaf fall, as well as late season storms that rewet dry soils, to serve as considerable sources of C, N, and P to boreal aquatic ecosystems.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Rulli, Mayra P. D. and Bergström, Ann-Kristin and Sponseller, Ryan A. and Berggren, Martin},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12064},\n\tkeywords = {\\#nosource},\n\tpages = {1169--1183},\n}\n\n\n\n\n\n Changes in nutrient bioavailability due to increased loading of dissolved organic matter (DOM) may impact boreal freshwaters. Yet, the relative bioavailability of carbon (C), nitrogen (N), and phosphorus (P) associated with terrestrial DOM remains poorly understood. We applied short-term bioassays with natural bacterial inocula to determine seasonal variation in bioavailable organic nutrient pools from four boreal headwater streams in northern Sweden. Experiments were designed to exhaust bioavailable nutrients associated with DOM by inducing limiting conditions when all required resources except for the targeted nutrient (C, N, or P) are provided in excess. We hypothesized that the supply of different bioavailable nutrients to streams would reflect seasonal variations in terrestrial demand, hydrology, and temperature. The delivery of bioavailable DOM-associated resources from the four streams were, on average, 2%, 11%, and 38% of the total dissolved organic C, N, and P, respectively, emphasizing the relatively low C bioavailability in these DOM-rich waters. Bioavailable N : P ratios peaked in autumn for all sites, with lower values in winter and spring. Both in terms of relative (% of total) and absolute bioavailable organic nutrient concentrations, the seasonal pattern was characterized by systematically high values for the autumn period. Furthermore, links between bioavailable resources and temperature and hydrology varied across sites, time periods, and the different elements. Thus, elevated concentrations of bioavailable organic resources in autumn suggest the potential for leaf fall, as well as late season storms that rewet dry soils, to serve as considerable sources of C, N, and P to boreal aquatic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Norway spruce postglacial recolonization of Fennoscandia.\n \n \n \n \n\n\n \n Nota, K.; Klaminder, J.; Milesi, P.; Bindler, R.; Nobile, A.; van Steijn, T.; Bertilsson, S.; Svensson, B.; Hirota, S. K.; Matsuo, A.; Gunnarsson, U.; Seppä, H.; Väliranta, M. M.; Wohlfarth, B.; Suyama, Y.; and Parducci, L.\n\n\n \n\n\n\n Nature Communications, 13(1): 1333. March 2022.\n Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{nota_norway_2022,\n\ttitle = {Norway spruce postglacial recolonization of {Fennoscandia}},\n\tvolume = {13},\n\tcopyright = {2022 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-022-28976-4},\n\tdoi = {10.1038/s41467-022-28976-4},\n\tabstract = {Contrasting theories exist regarding how Norway spruce (Picea abies) recolonized Fennoscandia after the last glaciation and both early Holocene establishments from western microrefugia and late Holocene colonization from the east have been postulated. Here, we show that Norway spruce was present in southern Fennoscandia as early as 14.7 ± 0.1 cal. kyr BP and that the millennia-old clonal spruce trees present today in central Sweden likely arrived with an early Holocene migration from the east. Our findings are based on ancient sedimentary DNA from multiple European sites (N = 15) combined with nuclear and mitochondrial DNA analysis of ancient clonal (N = 135) and contemporary spruce forest trees (N = 129) from central Sweden. Our other findings imply that Norway spruce was present shortly after deglaciation at the margins of the Scandinavian Ice Sheet, and support previously disputed finds of pollen in southern Sweden claiming spruce establishment during the Lateglacial.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Nature Communications},\n\tauthor = {Nota, Kevin and Klaminder, Jonatan and Milesi, Pascal and Bindler, Richard and Nobile, Alessandro and van Steijn, Tamara and Bertilsson, Stefan and Svensson, Brita and Hirota, Shun K. and Matsuo, Ayumi and Gunnarsson, Urban and Seppä, Heikki and Väliranta, Minna M. and Wohlfarth, Barbara and Suyama, Yoshihisa and Parducci, Laura},\n\tmonth = mar,\n\tyear = {2022},\n\tnote = {Publisher: Nature Publishing Group},\n\tkeywords = {Ecological genetics, Plant evolution},\n\tpages = {1333},\n}\n\n\n\n\n\n Contrasting theories exist regarding how Norway spruce (Picea abies) recolonized Fennoscandia after the last glaciation and both early Holocene establishments from western microrefugia and late Holocene colonization from the east have been postulated. Here, we show that Norway spruce was present in southern Fennoscandia as early as 14.7 ± 0.1 cal. kyr BP and that the millennia-old clonal spruce trees present today in central Sweden likely arrived with an early Holocene migration from the east. Our findings are based on ancient sedimentary DNA from multiple European sites (N = 15) combined with nuclear and mitochondrial DNA analysis of ancient clonal (N = 135) and contemporary spruce forest trees (N = 129) from central Sweden. Our other findings imply that Norway spruce was present shortly after deglaciation at the margins of the Scandinavian Ice Sheet, and support previously disputed finds of pollen in southern Sweden claiming spruce establishment during the Lateglacial.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of Habitat-Specific Primary Production on Fish Size, Biomass, and Production in Northern Oligotrophic Lakes.\n \n \n \n \n\n\n \n Norman, S.; Nilsson, K. A.; Klaus, M.; Seekell, D.; Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Ecosystems, 25(7): 1555–1570. November 2022.\n \n\n\n\n
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\n\n\n@article{norman_effects_2022,\n\ttitle = {Effects of {Habitat}-{Specific} {Primary} {Production} on {Fish} {Size}, {Biomass}, and {Production} in {Northern} {Oligotrophic} {Lakes}},\n\tvolume = {25},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-021-00733-6},\n\tdoi = {10.1007/s10021-021-00733-6},\n\tabstract = {Ecological theory predicts that the relative distribution of primary production across habitats influence fish size structure and biomass production. In this study, we assessed individual, population, and community-level consequences for brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) of variation in estimated habitat specific (benthic and pelagic) and total whole lake (GPPwhole) gross primary production in 27 northern oligotrophic lakes. We found that higher contribution of benthic primary production to GPPwhole was associated with higher community biomass and larger maximum and mean sizes of fish. At the population level, species-specific responses differed. Increased benthic primary production (GPPBenthic) correlated to higher population biomass of brown trout regardless of being alone or in sympatry, while Arctic char responded positively to pelagic primary production (GPPPelagic) in sympatric populations. In sympatric lakes, the maximum size of both species was positively related to both GPPBenthic and the benthic contribution to GPPWhole. In allopatric lakes, brown trout mean and maximum size and Arctic char mean size were positively related to the benthic proportion of GPPWhole. Our results highlight the importance of light-controlled benthic primary production for fish biomass production in oligotrophic northern lakes. Our results further suggest that consequences of ontogenetic asymmetry and niche shifts may cause the distribution of primary production across habitats to be more important than the total ecosystem primary production for fish size, population biomass, and production. Awareness of the relationships between light availability and asymmetric resource production favoring large fish and fish production may allow for cost-efficient and more informed management actions in northern oligotrophic lakes.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Norman, Sven and Nilsson, Karin A. and Klaus, Marcus and Seekell, David and Karlsson, Jan and Byström, Pär},\n\tmonth = nov,\n\tyear = {2022},\n\tkeywords = {\\#nosource, Arctic char, Benthic primary production, Brown trout, Keywords, Lake productivity, Ontogenetic asymmetry, Pelagic primary production},\n\tpages = {1555--1570},\n}\n\n\n\n\n\n Ecological theory predicts that the relative distribution of primary production across habitats influence fish size structure and biomass production. In this study, we assessed individual, population, and community-level consequences for brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) of variation in estimated habitat specific (benthic and pelagic) and total whole lake (GPPwhole) gross primary production in 27 northern oligotrophic lakes. We found that higher contribution of benthic primary production to GPPwhole was associated with higher community biomass and larger maximum and mean sizes of fish. At the population level, species-specific responses differed. Increased benthic primary production (GPPBenthic) correlated to higher population biomass of brown trout regardless of being alone or in sympatry, while Arctic char responded positively to pelagic primary production (GPPPelagic) in sympatric populations. In sympatric lakes, the maximum size of both species was positively related to both GPPBenthic and the benthic contribution to GPPWhole. In allopatric lakes, brown trout mean and maximum size and Arctic char mean size were positively related to the benthic proportion of GPPWhole. Our results highlight the importance of light-controlled benthic primary production for fish biomass production in oligotrophic northern lakes. Our results further suggest that consequences of ontogenetic asymmetry and niche shifts may cause the distribution of primary production across habitats to be more important than the total ecosystem primary production for fish size, population biomass, and production. Awareness of the relationships between light availability and asymmetric resource production favoring large fish and fish production may allow for cost-efficient and more informed management actions in northern oligotrophic lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the Arctic.\n \n \n \n \n\n\n \n Lento, J.; Culp, J. M.; Levenstein, B.; Aroviita, J.; Baturina, M. A.; Bogan, D.; Brittain, J. E.; Chin, K.; Christoffersen, K. S.; Docherty, C.; Friberg, N.; Ingimarsson, F.; Jacobsen, D.; Lau, D. C. P.; Loskutova, O. A.; Milner, A.; Mykrä, H.; Novichkova, A. A.; Ólafsson, J. S.; Schartau, A. K.; Shaftel, R.; and Goedkoop, W.\n\n\n \n\n\n\n Freshwater Biology, 67(1): 159–175. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13805\n\n\n\n
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\n\n\n@article{lento_temperature_2022,\n\ttitle = {Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the {Arctic}},\n\tvolume = {67},\n\tcopyright = {© 2021 The Authors. Freshwater Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2427},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.13805},\n\tdoi = {10.1111/fwb.13805},\n\tabstract = {Warming in the Arctic is predicted to change freshwater biodiversity through loss of unique taxa and northward range expansion of lower latitude taxa. Detecting such changes requires establishing circumpolar baselines for diversity, and understanding the primary drivers of diversity. We examined benthic macroinvertebrate diversity using a circumpolar dataset of {\\textgreater}1,500 Arctic lake and river sites. Rarefied α diversity within catchments was assessed along latitude and temperature gradients. Community composition was assessed through region-scale analysis of β diversity and its components (nestedness and turnover), and analysis of biotic–abiotic relationships. Rarefied α diversity of lakes and rivers declined with increasing latitude, although more strongly across mainland regions than islands. Diversity was strongly related to air temperature, with the lowest diversity in the coldest catchments. Regional dissimilarity was highest when mainland regions were compared with islands, suggesting that connectivity limitations led to the strongest dissimilarity. High contributions of nestedness indicated that island regions contained a subset of the taxa found in mainland regions. High Arctic rivers and lakes were predominately occupied by Chironomidae and Oligochaeta, whereas Ephemeroptera, Plecoptera, and Trichoptera taxa were more abundant at lower latitudes. Community composition was strongly associated with temperature, although geology and precipitation were also important correlates. The strong association with temperature supports the prediction that warming will increase Arctic macroinvertebrate diversity, although low diversity on islands suggests that this increase will be limited by biogeographical constraints. Long-term harmonised monitoring across the circumpolar region is necessary to detect such changes to diversity and inform science-based management.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Freshwater Biology},\n\tauthor = {Lento, Jennifer and Culp, Joseph M. and Levenstein, Brianna and Aroviita, Jukka and Baturina, Maria A. and Bogan, Daniel and Brittain, John E. and Chin, Krista and Christoffersen, Kirsten S. and Docherty, Catherine and Friberg, Nikolai and Ingimarsson, Finnur and Jacobsen, Dean and Lau, Danny Chun Pong and Loskutova, Olga A. and Milner, Alexander and Mykrä, Heikki and Novichkova, Anna A. and Ólafsson, Jón S. and Schartau, Ann Kristin and Shaftel, Rebecca and Goedkoop, Willem},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13805},\n\tkeywords = {\\#nosource, benthic invertebrates, dispersal, diversity, high latitude, lake, river},\n\tpages = {159--175},\n}\n\n\n\n\n\n Warming in the Arctic is predicted to change freshwater biodiversity through loss of unique taxa and northward range expansion of lower latitude taxa. Detecting such changes requires establishing circumpolar baselines for diversity, and understanding the primary drivers of diversity. We examined benthic macroinvertebrate diversity using a circumpolar dataset of \\textgreater1,500 Arctic lake and river sites. Rarefied α diversity within catchments was assessed along latitude and temperature gradients. Community composition was assessed through region-scale analysis of β diversity and its components (nestedness and turnover), and analysis of biotic–abiotic relationships. Rarefied α diversity of lakes and rivers declined with increasing latitude, although more strongly across mainland regions than islands. Diversity was strongly related to air temperature, with the lowest diversity in the coldest catchments. Regional dissimilarity was highest when mainland regions were compared with islands, suggesting that connectivity limitations led to the strongest dissimilarity. High contributions of nestedness indicated that island regions contained a subset of the taxa found in mainland regions. High Arctic rivers and lakes were predominately occupied by Chironomidae and Oligochaeta, whereas Ephemeroptera, Plecoptera, and Trichoptera taxa were more abundant at lower latitudes. Community composition was strongly associated with temperature, although geology and precipitation were also important correlates. The strong association with temperature supports the prediction that warming will increase Arctic macroinvertebrate diversity, although low diversity on islands suggests that this increase will be limited by biogeographical constraints. Long-term harmonised monitoring across the circumpolar region is necessary to detect such changes to diversity and inform science-based management.\n
\n\n\n\n \n\n \n \n \n \n \n \n Non-native species change the tune of tundra soils: Novel access to soundscapes of the Arctic earthworm invasion.\n \n \n \n \n\n\n \n Keen, S. C.; Wackett, A. A.; Willenbring, J. K.; Yoo, K.; Jonsson, H.; Clow, T.; and Klaminder, J.\n\n\n \n\n\n\n Science of The Total Environment, 838: 155976. September 2022.\n \n\n\n\n
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\n\n\n@article{keen_non-native_2022,\n\ttitle = {Non-native species change the tune of tundra soils: {Novel} access to soundscapes of the {Arctic} earthworm invasion},\n\tvolume = {838},\n\tissn = {0048-9697},\n\tshorttitle = {Non-native species change the tune of tundra soils},\n\turl = {https://www.sciencedirect.com/science/article/pii/S004896972203073X},\n\tdoi = {10.1016/j.scitotenv.2022.155976},\n\tabstract = {Over the last decade, an increasing number of studies have used soundscapes to address diverse ecological questions. Sound represents one of the few sources of information capable of providing in situ insights into processes occurring within opaque soil matrices. To date, the use of soundscapes for soil macrofauna monitoring has been experimentally tested only in controlled laboratory environments. Here we assess the validity of laboratory predictions and explore the use of soil soundscape proxies for monitoring soil macrofauna (i.e., earthworm) activities in an outdoor context. In a common garden experiment in northern Sweden, we constructed outdoor mesocosm plots (N = 36) containing two different Arctic vegetation types (meadow and heath) and introduced earthworms to half of these plots. Earthworms substantially altered the ambient soil soundscape under both vegetation types, as measured by both traditional soundscape indices and frequency band power levels, although their acoustic impacts were expressed differently in heath versus meadow soils. While these findings support the as-of-yet untapped promise of using belowground soundscape analyses to monitor soil ecosystem health, direct acoustic emissions from earthworm activities appear to be an unlikely proxy for tracking worm activities at daily timescales. Instead, earthworms indirectly altered the soil soundscape by ‘re-engineering’ the soil matrix: an effect that was dependent on vegetation type. Our findings suggest that long-term (i.e., seasonal) earthworm activities in natural soil settings can likely be monitored indirectly via their impacts on soundscape measures and acoustic indices. Analyzing soil soundscapes may enable larger-scale monitoring of high-latitude soils and is directly applicable to the specific case of earthworm invasions within Arctic soils, which has recently been identified as a potential threat to the resilience of high-latitude ecosystems. Soil soundscapes could also offer a novel means to monitor soils and soil-plant-faunal interactions in situ across diverse pedogenic, agronomic, and ecological systems.},\n\turldate = {2024-03-26},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Keen, Sara C. and Wackett, Adrian A. and Willenbring, Jane K. and Yoo, Kyungsoo and Jonsson, Hanna and Clow, Travis and Klaminder, Jonatan},\n\tmonth = sep,\n\tyear = {2022},\n\tkeywords = {\\#nosource, Acoustic monitoring, Arctic, Earthworm invasion, Ecosystem disturbance, Ecosystem engineer, Soil fauna, Soil organic carbon, Soil structure, Soundscapes},\n\tpages = {155976},\n}\n\n\n\n\n\n Over the last decade, an increasing number of studies have used soundscapes to address diverse ecological questions. Sound represents one of the few sources of information capable of providing in situ insights into processes occurring within opaque soil matrices. To date, the use of soundscapes for soil macrofauna monitoring has been experimentally tested only in controlled laboratory environments. Here we assess the validity of laboratory predictions and explore the use of soil soundscape proxies for monitoring soil macrofauna (i.e., earthworm) activities in an outdoor context. In a common garden experiment in northern Sweden, we constructed outdoor mesocosm plots (N = 36) containing two different Arctic vegetation types (meadow and heath) and introduced earthworms to half of these plots. Earthworms substantially altered the ambient soil soundscape under both vegetation types, as measured by both traditional soundscape indices and frequency band power levels, although their acoustic impacts were expressed differently in heath versus meadow soils. While these findings support the as-of-yet untapped promise of using belowground soundscape analyses to monitor soil ecosystem health, direct acoustic emissions from earthworm activities appear to be an unlikely proxy for tracking worm activities at daily timescales. Instead, earthworms indirectly altered the soil soundscape by ‘re-engineering’ the soil matrix: an effect that was dependent on vegetation type. Our findings suggest that long-term (i.e., seasonal) earthworm activities in natural soil settings can likely be monitored indirectly via their impacts on soundscape measures and acoustic indices. Analyzing soil soundscapes may enable larger-scale monitoring of high-latitude soils and is directly applicable to the specific case of earthworm invasions within Arctic soils, which has recently been identified as a potential threat to the resilience of high-latitude ecosystems. Soil soundscapes could also offer a novel means to monitor soils and soil-plant-faunal interactions in situ across diverse pedogenic, agronomic, and ecological systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Trapped between drowning and desiccation: Riverine plants under hydropeaking.\n \n \n \n \n\n\n \n Baladrón, A.; Bejarano, M. D.; Sarneel, J. M.; and Boavida, I.\n\n\n \n\n\n\n Science of The Total Environment, 829: 154451. July 2022.\n \n\n\n\n
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\n\n\n@article{baladron_trapped_2022,\n\ttitle = {Trapped between drowning and desiccation: {Riverine} plants under hydropeaking},\n\tvolume = {829},\n\tissn = {0048-9697},\n\tshorttitle = {Trapped between drowning and desiccation},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969722015443},\n\tdoi = {10.1016/j.scitotenv.2022.154451},\n\tabstract = {Hydropeaking is part of hydropower production. The discontinuous release of turbined water during hydropeaking generates sudden rise and falls of the water levels, as well as extended droughts. These artificial flow fluctuations impose challenging growing conditions for riverine vegetation. In order to identify vulnerable/resistant plant species to hydropeaking and to evaluate the impact of contrasting hydropeaking scenarios (simplified (i.e., sudden deep floods, frequent soil saturation and drought) and real-life, power plant-induced scenarios), we measured germination, survival, and morphological and physiological attributes of a selection of 14 plant species commonly found along riparian areas. Species were subject to different hydropeaking scenarios during three months (vegetative period) in the field and in a greenhouse. Half of the species performed worse under hydropeaking in comparison to the control (e.g., less germination and biomass, lower growth rates, reduced stem and root length, physiological stress) but none of the tested hydropeaking scenarios was clearly more disruptive than others. Betula pubescens, Alnus incana and Filipendula ulmifolia showed the largest vulnerability to hydropeaking, while other species (e.g., Carex acuta) were resistant to it. Both in the field and in the greenhouse, plants in perturbed scenarios accumulated more 13C than in the control scenario indicating limited capacity to perform 13C isotope discrimination and evidencing plant physiological stress. The highest 13C abundances were found under drought or flooding conditions in the greenhouse, and under the highest hydropeaking intensities in the field (e.g., Betula pubescens). Our results suggest that any hydropeaking scheme can be equally detrimental in terms of plant performance. Hydropeaking schemes that combine periods of severe drought with long and frequent flooding episodes may create a hostile environment for riverine species. Further research on “hydropeaking-tolerant” plant traits is key to draw the boundaries beyond which riverine species can germinate, grow and complete their life cycle under hydropeaking.},\n\turldate = {2024-03-26},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Baladrón, Alejandro and Bejarano, María Dolores and Sarneel, Judith M. and Boavida, Isabel},\n\tmonth = jul,\n\tyear = {2022},\n\tkeywords = {Drought, Flooding, Hydropeaking, Plant morphology, Riverine vegetation, Stoichiometry},\n\tpages = {154451},\n}\n\n\n\n\n\n Hydropeaking is part of hydropower production. The discontinuous release of turbined water during hydropeaking generates sudden rise and falls of the water levels, as well as extended droughts. These artificial flow fluctuations impose challenging growing conditions for riverine vegetation. In order to identify vulnerable/resistant plant species to hydropeaking and to evaluate the impact of contrasting hydropeaking scenarios (simplified (i.e., sudden deep floods, frequent soil saturation and drought) and real-life, power plant-induced scenarios), we measured germination, survival, and morphological and physiological attributes of a selection of 14 plant species commonly found along riparian areas. Species were subject to different hydropeaking scenarios during three months (vegetative period) in the field and in a greenhouse. Half of the species performed worse under hydropeaking in comparison to the control (e.g., less germination and biomass, lower growth rates, reduced stem and root length, physiological stress) but none of the tested hydropeaking scenarios was clearly more disruptive than others. Betula pubescens, Alnus incana and Filipendula ulmifolia showed the largest vulnerability to hydropeaking, while other species (e.g., Carex acuta) were resistant to it. Both in the field and in the greenhouse, plants in perturbed scenarios accumulated more 13C than in the control scenario indicating limited capacity to perform 13C isotope discrimination and evidencing plant physiological stress. The highest 13C abundances were found under drought or flooding conditions in the greenhouse, and under the highest hydropeaking intensities in the field (e.g., Betula pubescens). Our results suggest that any hydropeaking scheme can be equally detrimental in terms of plant performance. Hydropeaking schemes that combine periods of severe drought with long and frequent flooding episodes may create a hostile environment for riverine species. Further research on “hydropeaking-tolerant” plant traits is key to draw the boundaries beyond which riverine species can germinate, grow and complete their life cycle under hydropeaking.\n
\n\n\n\n \n\n \n \n \n \n \n \n A high spatial resolution soil carbon and nitrogen dataset for the northern permafrost region based on circumpolar land cover upscaling.\n \n \n \n \n\n\n \n Palmtag, J.; Obu, J.; Kuhry, P.; Richter, A.; Siewert, M. B.; Weiss, N.; Westermann, S.; and Hugelius, G.\n\n\n \n\n\n\n Earth System Science Data, 14(9): 4095–4110. 2022.\n Publisher: Copernicus Publications\n\n\n\n
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\n\n\n@article{palmtag_high_2022,\n\ttitle = {A high spatial resolution soil carbon and nitrogen dataset for the northern permafrost region based on circumpolar land cover upscaling},\n\tvolume = {14},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-203690},\n\tdoi = {10.5194/essd-14-4095-2022},\n\tabstract = {Soils in the northern high latitudes are a key component in the global carbon cycle; the northern permafrost region covers 22\\% of the Northern Hemisphere land surface area and holds almost twice as ...},\n\tlanguage = {eng},\n\tnumber = {9},\n\turldate = {2024-03-26},\n\tjournal = {Earth System Science Data},\n\tauthor = {Palmtag, Juri and Obu, Jaroslav and Kuhry, Peter and Richter, Andreas and Siewert, Matthias B. and Weiss, Niels and Westermann, Sebastian and Hugelius, Gustaf},\n\tyear = {2022},\n\tnote = {Publisher: Copernicus Publications},\n\tpages = {4095--4110},\n}\n\n\n\n\n\n Soils in the northern high latitudes are a key component in the global carbon cycle; the northern permafrost region covers 22% of the Northern Hemisphere land surface area and holds almost twice as ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Winters are changing : snow effects on Arctic and alpine tundra ecosystems.\n \n \n \n \n\n\n \n Rixen, C.; Hoye, T. T.; Macek, P.; Aerts, R.; Alatalo, J. M.; Anderson, J. T.; Arnold, P. A.; Barrio, I. C.; Bjerke, J. W.; Bjorkman, M. P.; Blok, D.; Blume-Werry, G.; Boike, J.; Bokhorst, S.; Carbognani, M.; Christiansen, C. T.; Convey, P.; Cooper, E. J.; Cornelissen, J. H. C.; Coulson, S. J.; Dorrepaal, E.; Elberling, B.; Elmendorf, S. C.; Elphinstone, C.; Forte, T. G. W.; Frei, E. R.; Geange, S. R.; Gehrmann, F.; Gibson, C.; Grogan, P.; Halbritter, A. H.; Harte, J.; Henry, G. H. R.; Inouye, D. W.; Irwin, R. E.; Jespersen, G.; Jonsdottir, I. S.; Jung, J. Y.; Klinges, D. H.; Kudo, G.; Lamsa, J.; Lee, H.; Lembrechts, J. J.; Lett, S.; Lynn, J. S.; Mann, H. M. R.; Mastepanov, M.; Morse, J.; Myers-Smith, I. H.; Olofsson, J.; Paavola, R.; Petraglia, A.; Phoenix, G. K.; Semenchuk, P.; Siewert, M. B.; Slatyer, R.; Spasojevic, M. J.; Suding, K.; Sullivan, P.; Thompson, K. L.; Vaisanen, M.; Vandvik, V.; Venn, S.; Walz, J.; Way, R.; Welker, J. M.; Wipf, S.; and Zong, S.\n\n\n \n\n\n\n Arctic Science, 8(3): 572–608. 2022.\n Publisher: Canadian Science Publishing\n\n\n\n
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\n\n\n@article{rixen_winters_2022,\n\ttitle = {Winters are changing : snow effects on {Arctic} and alpine tundra ecosystems},\n\tvolume = {8},\n\tshorttitle = {Winters are changing},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-218120},\n\tdoi = {10.1139/as-2020-0058},\n\tabstract = {Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the gr ...},\n\tlanguage = {eng},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Arctic Science},\n\tauthor = {Rixen, Christian and Hoye, Toke Thomas and Macek, Petr and Aerts, Rien and Alatalo, Juha M. and Anderson, Jill T. and Arnold, Pieter A. and Barrio, Isabel C. and Bjerke, Jarle W. and Bjorkman, Mats P. and Blok, Daan and Blume-Werry, Gesche and Boike, Julia and Bokhorst, Stef and Carbognani, Michele and Christiansen, Casper T. and Convey, Peter and Cooper, Elisabeth J. and Cornelissen, J. Hans C. and Coulson, Stephen J. and Dorrepaal, Ellen and Elberling, Bo and Elmendorf, Sarah C. and Elphinstone, Cassandra and Forte, T'ai G. W. and Frei, Esther R. and Geange, Sonya R. and Gehrmann, Friederike and Gibson, Casey and Grogan, Paul and Halbritter, Aud Helen and Harte, John and Henry, Gregory H. R. and Inouye, David W. and Irwin, Rebecca E. and Jespersen, Gus and Jonsdottir, Ingibjorg Svala and Jung, Ji Young and Klinges, David H. and Kudo, Gaku and Lamsa, Juho and Lee, Hanna and Lembrechts, Jonas J. and Lett, Signe and Lynn, Joshua Scott and Mann, Hjalte M. R. and Mastepanov, Mikhail and Morse, Jennifer and Myers-Smith, Isla H. and Olofsson, Johan and Paavola, Riku and Petraglia, Alessandro and Phoenix, Gareth K. and Semenchuk, Philipp and Siewert, Matthias B. and Slatyer, Rachel and Spasojevic, Marko J. and Suding, Katharine and Sullivan, Patrick and Thompson, Kimberly L. and Vaisanen, Maria and Vandvik, Vigdis and Venn, Susanna and Walz, Josefine and Way, Robert and Welker, Jeffrey M. and Wipf, Sonja and Zong, Shengwei},\n\tyear = {2022},\n\tnote = {Publisher: Canadian Science Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {572--608},\n}\n\n\n\n\n\n Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the gr ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Co-occurrence of browning and oligotrophication in a boreal stream network.\n \n \n \n \n\n\n \n Mosquera, V.; Maher Hasselquist, E.; Sponseller, R. A.; and Laudon, H.\n\n\n \n\n\n\n Limnology and Oceanography, 67(10): 2325–2339. 2022.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{mosquera_co-occurrence_2022,\n\ttitle = {Co-occurrence of browning and oligotrophication in a boreal stream network},\n\tvolume = {67},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-199209},\n\tdoi = {10.1002/lno.12205},\n\tabstract = {The relative supply of carbon (C), nitrogen (N), and phosphorus (P) to freshwater ecosystems is of fundamental importance to aquatic productivity, nutrient cycling, and food web dynamics. In northe ...},\n\tlanguage = {eng},\n\tnumber = {10},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Mosquera, Virginia and Maher Hasselquist, Eliza and Sponseller, Ryan A. and Laudon, Hjalmar},\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {2325--2339},\n}\n\n\n\n\n\n The relative supply of carbon (C), nitrogen (N), and phosphorus (P) to freshwater ecosystems is of fundamental importance to aquatic productivity, nutrient cycling, and food web dynamics. In northe ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Landscape determinants of pelagic and benthic primary production in northern lakes.\n \n \n \n \n\n\n \n Puts, I. C.; Ask, J.; Siewert, M. B.; Sponseller, R. A.; Hessen, D. O.; and Bergström, A.\n\n\n \n\n\n\n Global Change Biology, 28(23): 7063–7077. 2022.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{puts_landscape_2022,\n\ttitle = {Landscape determinants of pelagic and benthic primary production in northern lakes},\n\tvolume = {28},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-194518},\n\tdoi = {10.1111/gcb.16409},\n\tabstract = {Global change affects gross primary production (GPP) in benthic and pelagic habitats of northern lakes by influencing catchment characteristics and lake water biogeochemistry. However, how changes ...},\n\tlanguage = {eng},\n\tnumber = {23},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Puts, Isolde C. and Ask, Jenny and Siewert, Matthias B. and Sponseller, Ryan A. and Hessen, Dag O. and Bergström, Ann-Kristin},\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {7063--7077},\n}\n\n\n\n\n\n Global change affects gross primary production (GPP) in benthic and pelagic habitats of northern lakes by influencing catchment characteristics and lake water biogeochemistry. However, how changes ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Resolving the Drivers of Algal Nutrient Limitation from Boreal to Arctic Lakes and Streams.\n \n \n \n \n\n\n \n Myrstener, M.; Fork, M. L.; Bergström, A.; Puts, I.; Hauptmann, D.; Isles, P. D. F.; Burrows, R. M.; and Sponseller, R. A.\n\n\n \n\n\n\n Ecosystems (New York. Print), 25: 1682–1699. 2022.\n Publisher: Springer-Verlag New York\n\n\n\n
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\n\n\n@article{myrstener_resolving_2022,\n\ttitle = {Resolving the {Drivers} of {Algal} {Nutrient} {Limitation} from {Boreal} to {Arctic} {Lakes} and {Streams}},\n\tvolume = {25},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-194276},\n\tdoi = {10.1007/s10021-022-00759-4},\n\tabstract = {Nutrient inputs to northern freshwaters are changing, potentially altering aquatic ecosystem functioning through effects on primary producers. Yet, while primary producer growth is sensitive to nut ...},\n\tlanguage = {eng},\n\turldate = {2024-03-26},\n\tjournal = {Ecosystems (New York. Print)},\n\tauthor = {Myrstener, Maria and Fork, Megan L. and Bergström, Ann-Kristin and Puts, Isolde and Hauptmann, Demian and Isles, Peter D. F. and Burrows, Ryan M. and Sponseller, Ryan A.},\n\tyear = {2022},\n\tnote = {Publisher: Springer-Verlag New York},\n\tpages = {1682--1699},\n}\n\n\n\n\n\n\n\n\n\n Nutrient inputs to northern freshwaters are changing, potentially altering aquatic ecosystem functioning through effects on primary producers. Yet, while primary producer growth is sensitive to nut ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon emission and export from the Ket River, western Siberia.\n \n \n \n \n\n\n \n Lim, A. G.; Krickov, I. V.; Vorobyev, S. N.; Korets, M. A.; Kopysov, S.; Shirokova, L. S.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Biogeosciences, 19(24): 5859–5877. 2022.\n Publisher: Copernicus Publications\n\n\n\n
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\n\n\n@article{lim_carbon_2022,\n\ttitle = {Carbon emission and export from the {Ket} {River}, western {Siberia}},\n\tvolume = {19},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-202587},\n\tdoi = {10.5194/bg-19-5859-2022},\n\tabstract = {Despite recent progress in the understanding of the carbon (C) cycle of Siberian permafrost-affected rivers, spatial and seasonal dynamics of C export and emission from medium-sized rivers (50 000- ...},\n\tlanguage = {eng},\n\tnumber = {24},\n\turldate = {2024-03-26},\n\tjournal = {Biogeosciences},\n\tauthor = {Lim, Artem G. and Krickov, Ivan V. and Vorobyev, Sergey N. and Korets, Mikhail A. and Kopysov, Sergey and Shirokova, Liudmila S. and Karlsson, Jan and Pokrovsky, Oleg S.},\n\tyear = {2022},\n\tnote = {Publisher: Copernicus Publications},\n\tpages = {5859--5877},\n}\n\n\n\n\n\n Despite recent progress in the understanding of the carbon (C) cycle of Siberian permafrost-affected rivers, spatial and seasonal dynamics of C export and emission from medium-sized rivers (50 000- ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Multitrophic biodiversity patterns and environmental descriptors of sub‐Arctic lakes in northern Europe.\n \n \n \n \n\n\n \n Lau, D. C. P.; Christoffersen, K. S.; Erkinaro, J.; Hayden, B.; Heino, J.; Hellsten, S.; Holmgren, K.; Kahilainen, K. K.; Kahlert, M.; Satu Maaria, K.; Karlsson, J.; Forsström, L.; Lento, J.; Mjelde, M.; Ruuhijärvi, J.; Sandøy, S.; Schartau, A. K.; Svenning, M.; Vrede, T.; and Goedkoop, W.\n\n\n \n\n\n\n Freshwater Biology, 67(1): 30–48. 2022.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{lau_multitrophic_2022,\n\ttitle = {Multitrophic biodiversity patterns and environmental descriptors of sub‐{Arctic} lakes in northern {Europe}},\n\tvolume = {67},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-177612},\n\tdoi = {10.1111/fwb.13477},\n\tabstract = {1. Arctic and sub‐Arctic lakes in northern Europe are increasingly threatened by climate change, which can affect their biodiversity directly by shifting thermal and hydrological regimes, and indir ...},\n\tlanguage = {eng},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Freshwater Biology},\n\tauthor = {Lau, Danny C. P. and Christoffersen, Kirsten S. and Erkinaro, Jaakko and Hayden, Brian and Heino, Jani and Hellsten, Seppo and Holmgren, Kerstin and Kahilainen, Kimmo K. and Kahlert, Maria and Satu Maaria, Karjalainen and Karlsson, Jan and Forsström, Laura and Lento, Jennifer and Mjelde, Marit and Ruuhijärvi, Jukka and Sandøy, Steinar and Schartau, Ann Kristin and Svenning, Martin-A. and Vrede, Tobias and Goedkoop, Willem},\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tpages = {30--48},\n}\n\n\n\n\n\n 1. Arctic and sub‐Arctic lakes in northern Europe are increasingly threatened by climate change, which can affect their biodiversity directly by shifting thermal and hydrological regimes, and indir ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Spatial and temporal variation in Arctic freshwater chemistry : Reflecting climate-induced landscape alterations and a changing template for biodiversity.\n \n \n \n \n\n\n \n Huser, B. J.; Futter, M. N.; Bogan, D.; Brittain, J. E.; Culp, J. M.; Goedkoop, W.; Gribovskaya, I.; Karlsson, J.; Lau, D. C. P.; Ruhland, K. M.; Schartau, A. K.; Shaftel, R.; Smol, J. P.; Vrede, T.; and Lento, J.\n\n\n \n\n\n\n Freshwater Biology, 67(1): 14–29. 2022.\n Publisher: John Wiley & Sons\n\n\n\n
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\n\n\n@article{huser_spatial_2022,\n\ttitle = {Spatial and temporal variation in {Arctic} freshwater chemistry : {Reflecting} climate-induced landscape alterations and a changing template for biodiversity},\n\tvolume = {67},\n\tshorttitle = {Spatial and temporal variation in {Arctic} freshwater chemistry},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-177313},\n\tdoi = {10.1111/fwb.13645},\n\tabstract = {1. Freshwater chemistry across the circumpolar region was characterised using a pan-Arctic data set from 1,032 lake and 482 river stations. Temporal trends were estimated for Early (1970-1985), Mid ...},\n\tlanguage = {eng},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Freshwater Biology},\n\tauthor = {Huser, Brian J. and Futter, Martyn N. and Bogan, Daniel and Brittain, John E. and Culp, Joseph M. and Goedkoop, Willem and Gribovskaya, Iliada and Karlsson, Jan and Lau, Danny C. P. and Ruhland, Kathleen M. and Schartau, Ann Kristin and Shaftel, Rebecca and Smol, John P. and Vrede, Tobias and Lento, Jennifer},\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons},\n\tkeywords = {\\#nosource, biogeochemistry, eutrophication, lakes, oligotrophication, rivers},\n\tpages = {14--29},\n}\n\n\n\n\n\n 1. Freshwater chemistry across the circumpolar region was characterised using a pan-Arctic data set from 1,032 lake and 482 river stations. Temporal trends were estimated for Early (1970-1985), Mid ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Circumpolar impacts of herbivores on Arctic tundra vegetation.\n \n \n \n \n\n\n \n Lindén, E.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2022.\n Publisher: Umeå Universitet\n\n\n\n
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\n\n\n@phdthesis{linden_circumpolar_2022,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Circumpolar impacts of herbivores on {Arctic} tundra vegetation},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-194189},\n\tabstract = {Arctic tundra vegetation provides many ecological services that have implications for the global climate. However, the tundra biome is currently changing in response to increasing temperatures. Her ...},\n\tlanguage = {eng},\n\turldate = {2023-07-25},\n\tschool = {Umeå University},\n\tauthor = {Lindén, Elin},\n\tcollaborator = {Olofsson, Johan and Sundqvist, Maja K. and te Beest, Mariska},\n\tyear = {2022},\n\tnote = {Publisher: Umeå Universitet},\n\tkeywords = {⛔ No DOI found},\n}\n\n\n\n\n\n Arctic tundra vegetation provides many ecological services that have implications for the global climate. However, the tundra biome is currently changing in response to increasing temperatures. Her ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Lowland plant arrival in alpine ecosystems facilitates a decrease in soil carbon content under experimental climate warming.\n \n \n \n \n\n\n \n Walker, T. W.; Gavazov, K.; Guillaume, T.; Lambert, T.; Mariotte, P.; Routh, D.; Signarbieux, C.; Block, S.; Münkemüller, T.; Nomoto, H.; Crowther, T. W; Richter, A.; Buttler, A.; and Alexander, J. M\n\n\n \n\n\n\n eLife, 11: e78555. May 2022.\n Publisher: eLife Sciences Publications, Ltd\n\n\n\n
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\n\n\n@article{walker_lowland_2022,\n\ttitle = {Lowland plant arrival in alpine ecosystems facilitates a decrease in soil carbon content under experimental climate warming},\n\tvolume = {11},\n\tissn = {2050-084X},\n\turl = {https://doi.org/10.7554/eLife.78555},\n\tdoi = {10.7554/eLife.78555},\n\tabstract = {Climate warming is releasing carbon from soils around the world, constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems. Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown. Here, we used two whole-community transplant experiments and a follow-up glasshouse experiment to determine whether the establishment of herbaceous lowland plants in alpine ecosystems influences soil carbon content under warming. We found that warming (transplantation to low elevation) led to a negligible decrease in alpine soil carbon content, but its effects became significant and 52\\% ± 31\\% (mean ± 95\\% confidence intervals) larger after lowland plants were introduced at low density into the ecosystem. We present evidence that decreases in soil carbon content likely occurred via lowland plants increasing rates of root exudation, soil microbial respiration, and CO2 release under warming. Our findings suggest that warming-induced range expansions of herbaceous plants have the potential to alter climate feedbacks from this system, and that plant range expansions among herbaceous communities may be an overlooked mediator of warming effects on carbon dynamics.},\n\tjournal = {eLife},\n\tauthor = {Walker, Tom WN and Gavazov, Konstantin and Guillaume, Thomas and Lambert, Thibault and Mariotte, Pierre and Routh, Devin and Signarbieux, Constant and Block, Sebastián and Münkemüller, Tamara and Nomoto, Hanna and Crowther, Thomas W and Richter, Andreas and Buttler, Alexandre and Alexander, Jake M},\n\teditor = {Schmid, Bernhard and Schuman, Meredith C and Schmid, Bernhard and Jing, Xin and Zhu, Biao},\n\tmonth = may,\n\tyear = {2022},\n\tnote = {Publisher: eLife Sciences Publications, Ltd},\n\tkeywords = {carbon cycling, climate change, plant ecophysiology, plant redistributions, plant–soil interactions, soil microbes},\n\tpages = {e78555},\n}\n\n\n\n\n\n Climate warming is releasing carbon from soils around the world, constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems. Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown. Here, we used two whole-community transplant experiments and a follow-up glasshouse experiment to determine whether the establishment of herbaceous lowland plants in alpine ecosystems influences soil carbon content under warming. We found that warming (transplantation to low elevation) led to a negligible decrease in alpine soil carbon content, but its effects became significant and 52% ± 31% (mean ± 95% confidence intervals) larger after lowland plants were introduced at low density into the ecosystem. We present evidence that decreases in soil carbon content likely occurred via lowland plants increasing rates of root exudation, soil microbial respiration, and CO2 release under warming. Our findings suggest that warming-induced range expansions of herbaceous plants have the potential to alter climate feedbacks from this system, and that plant range expansions among herbaceous communities may be an overlooked mediator of warming effects on carbon dynamics.\n
\n\n\n\n \n\n \n \n \n \n \n \n Vegetation change on mountaintops in northern Sweden: Stable vascular-plant but reordering of lichen and bryophyte communities.\n \n \n \n \n\n\n \n Hagenberg, L. W. C.; Vanneste, T.; Opedal, Ø. H.; Petlund, H. T.; Björkman, M. P.; Björk, R. G.; Holien, H.; Limpens, J.; Molau, U.; Graae, B. J.; and De Frenne, P.\n\n\n \n\n\n\n Ecological Research, 37(6): 722–737. November 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{hagenberg_vegetation_2022,\n\ttitle = {Vegetation change on mountaintops in northern {Sweden}: {Stable} vascular-plant but reordering of lichen and bryophyte communities},\n\tvolume = {37},\n\tissn = {0912-3814},\n\turl = {https://doi.org/10.1111/1440-1703.12359},\n\tdoi = {10.1111/1440-1703.12359},\n\tabstract = {Abstract Alpine ecosystems harbor remarkably diverse and distinct plant communities that are characteristically limited to harsh, and cold climatic conditions. As a result of thermal limitation to species occurrence, mountainous ecosystems are considered to be particularly sensitive to climate change. Our understanding of the impact of climate change is mainly based on vascular plants however, whereas cryptogams (i.e., lichens and bryophytes) are generally neglected or simply considered as one functional group. Here we aimed to improve our understanding of the drivers underlying temporal changes in vegetation of alpine ecosystems. To this end, we repeatedly surveyed the vegetation on four mountain summits along an elevational gradient in northern Sweden spanning a 19-year period. Our results show that the vascular plant communities remained relatively stable throughout the study period, despite fluctuations in terms of ground cover and species richness of shrubs and graminoids. In contrast, both lichens and bryophytes substantially decreased in cover and diversity, leading to alterations in community composition that were unrelated to vascular plant cover. Thermophilization of the vascular plant community was found only on the two intermediate summits. Our findings are only partially consistent with (long-term) climate-change impacts, and we argue that local non-climatic drivers such as herbivory might offset vegetation responses to warming. Hence, we underline the importance of considering local non-climatic drivers when evaluating temporal vegetation change in biologically complex systems.},\n\tnumber = {6},\n\turldate = {2023-07-22},\n\tjournal = {Ecological Research},\n\tauthor = {Hagenberg, Liyenne Wu Chen and Vanneste, Thomas and Opedal, Øystein H. and Petlund, Hanne Torsdatter and Björkman, Mats P. and Björk, Robert G. and Holien, Håkon and Limpens, Juul and Molau, Ulf and Graae, Bente Jessen and De Frenne, Pieter},\n\tmonth = nov,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {alpine vegetation, climate change impact, ecosystem change, lichens and bryophytes, non-climatic drivers},\n\tpages = {722--737},\n}\n\n\n\n\n\n Abstract Alpine ecosystems harbor remarkably diverse and distinct plant communities that are characteristically limited to harsh, and cold climatic conditions. As a result of thermal limitation to species occurrence, mountainous ecosystems are considered to be particularly sensitive to climate change. Our understanding of the impact of climate change is mainly based on vascular plants however, whereas cryptogams (i.e., lichens and bryophytes) are generally neglected or simply considered as one functional group. Here we aimed to improve our understanding of the drivers underlying temporal changes in vegetation of alpine ecosystems. To this end, we repeatedly surveyed the vegetation on four mountain summits along an elevational gradient in northern Sweden spanning a 19-year period. Our results show that the vascular plant communities remained relatively stable throughout the study period, despite fluctuations in terms of ground cover and species richness of shrubs and graminoids. In contrast, both lichens and bryophytes substantially decreased in cover and diversity, leading to alterations in community composition that were unrelated to vascular plant cover. Thermophilization of the vascular plant community was found only on the two intermediate summits. Our findings are only partially consistent with (long-term) climate-change impacts, and we argue that local non-climatic drivers such as herbivory might offset vegetation responses to warming. Hence, we underline the importance of considering local non-climatic drivers when evaluating temporal vegetation change in biologically complex systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Patterns of free amino acids in tundra soils reflect mycorrhizal type, shrubification, and warming.\n \n \n \n \n\n\n \n Andresen, L. C.; Bodé, S.; Björk, R. G.; Michelsen, A.; Aerts, R.; Boeckx, P.; Cornelissen, J. H. C.; Klanderud, K.; van Logtestijn, R. S. P.; and Rütting, T.\n\n\n \n\n\n\n Mycorrhiza, 32(3): 305–313. July 2022.\n \n\n\n\n
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\n\n\n@article{andresen_patterns_2022,\n\ttitle = {Patterns of free amino acids in tundra soils reflect mycorrhizal type, shrubification, and warming},\n\tvolume = {32},\n\tissn = {1432-1890},\n\turl = {https://doi.org/10.1007/s00572-022-01075-4},\n\tdoi = {10.1007/s00572-022-01075-4},\n\tabstract = {The soil nitrogen (N) cycle in cold terrestrial ecosystems is slow and organically bound N is an important source of N for plants in these ecosystems. Many plant species can take up free amino acids from these infertile soils, either directly or indirectly via their mycorrhizal fungi. We hypothesized that plant community changes and local plant community differences will alter the soil free amino acid pool and composition; and that long-term warming could enhance this effect. To test this, we studied the composition of extractable free amino acids at five separate heath, meadow, and bog locations in subarctic and alpine Scandinavia, with long-term (13 to 24 years) warming manipulations. The plant communities all included a mixture of ecto-, ericoid-, and arbuscular mycorrhizal plant species. Vegetation dominated by grasses and forbs with arbuscular and non-mycorrhizal associations showed highest soil free amino acid content, distinguishing them from the sites dominated by shrubs with ecto- and ericoid-mycorrhizal associations. Warming increased shrub and decreased moss cover at two sites, and by using redundancy analysis, we found that altered soil free amino acid composition was related to this plant cover change. From this, we conclude that the mycorrhizal type is important in controlling soil N cycling and that expansion of shrubs with ectomycorrhiza (and to some extent ericoid mycorrhiza) can help retain N within the ecosystems by tightening the N cycle.},\n\tnumber = {3},\n\tjournal = {Mycorrhiza},\n\tauthor = {Andresen, Louise C. and Bodé, Samuel and Björk, Robert G. and Michelsen, Anders and Aerts, Rien and Boeckx, Pascal and Cornelissen, J. Hans C. and Klanderud, Kari and van Logtestijn, Richard S. P. and Rütting, Tobias},\n\tmonth = jul,\n\tyear = {2022},\n\tpages = {305--313},\n}\n\n\n\n\n\n The soil nitrogen (N) cycle in cold terrestrial ecosystems is slow and organically bound N is an important source of N for plants in these ecosystems. Many plant species can take up free amino acids from these infertile soils, either directly or indirectly via their mycorrhizal fungi. We hypothesized that plant community changes and local plant community differences will alter the soil free amino acid pool and composition; and that long-term warming could enhance this effect. To test this, we studied the composition of extractable free amino acids at five separate heath, meadow, and bog locations in subarctic and alpine Scandinavia, with long-term (13 to 24 years) warming manipulations. The plant communities all included a mixture of ecto-, ericoid-, and arbuscular mycorrhizal plant species. Vegetation dominated by grasses and forbs with arbuscular and non-mycorrhizal associations showed highest soil free amino acid content, distinguishing them from the sites dominated by shrubs with ecto- and ericoid-mycorrhizal associations. Warming increased shrub and decreased moss cover at two sites, and by using redundancy analysis, we found that altered soil free amino acid composition was related to this plant cover change. From this, we conclude that the mycorrhizal type is important in controlling soil N cycling and that expansion of shrubs with ectomycorrhiza (and to some extent ericoid mycorrhiza) can help retain N within the ecosystems by tightening the N cycle.\n
\n\n\n\n \n\n \n \n \n \n \n The size-distribution of earth’s lakes and ponds: Limits to power-law behavior.\n \n \n \n\n\n \n Cael, B.; Biggs, J.; and Seekell, D.\n\n\n \n\n\n\n Frontiers in Environmental Science, 10: 888735. August 2022.\n \n\n\n\n
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\n\n\n\n@article{cael_size-distribution_2022,\n\ttitle = {The size-distribution of earth’s lakes and ponds: {Limits} to power-law behavior},\n\tvolume = {10},\n\tdoi = {10.3389/fenvs.2022.888735},\n\tjournal = {Frontiers in Environmental Science},\n\tauthor = {Cael, B. and Biggs, Jeremy and Seekell, D.},\n\tmonth = aug,\n\tyear = {2022},\n\tpages = {888735},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Root traits and soil micro-organisms as drivers of plant–soil feedbacks within the sub-arctic tundra meadow.\n \n \n \n \n\n\n \n Spitzer, C. M.; Wardle, D. A.; Lindahl, B. D.; Sundqvist, M. K.; Gundale, M. J.; Fanin, N.; and Kardol, P.\n\n\n \n\n\n\n Journal of Ecology, 110(2): 466–478. February 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{spitzer_root_2022,\n\ttitle = {Root traits and soil micro-organisms as drivers of plant–soil feedbacks within the sub-arctic tundra meadow},\n\tvolume = {110},\n\tissn = {0022-0477},\n\turl = {https://doi.org/10.1111/1365-2745.13814},\n\tdoi = {10.1111/1365-2745.13814},\n\tabstract = {Abstract Plant?soil feedback (PSF) results from the influence of plants on the composition and abundance of various taxa and functional groups of soil micro-organisms, and their reciprocal effects on the plants. However, little is understood about the importance of fine root traits and root economic strategies in moderating microbial-driven PSF. We examined the relationships between PSF and 11 chemical and morphological root traits from 18 sub-arctic meadow plant species, as well as the soil microbial community composition which we characterized using phospholipid fatty acids (PLFAs) and high-throughput sequencing. We also investigated the importance of the root economics spectrum in influencing PSF, because it indicates plant below-ground economic strategies via trade-offs between resource acquisition and conservation. When we considered the entire root economics spectrum, we found that PSFs were more negative when root trait values were more acquisitive across the 18 species. In addition, PSF was more negative when values of root nitrogen content and root forks per root length were higher, and more positive when root dry matter content was higher. We additionally identified two fungal orders that were negatively related to PSF. However, we found no evidence that root traits influenced PSF through its relationship with these fungal orders. Synthesis. Our results provide evidence that for some fine root traits, the root economics spectrum and some fungal orders have an important role in influencing PSF. By investigating the roles of soil micro-organisms and fine root traits in driving PSF, this study enables us to better understand root trait?microbial linkages across species and therefore offers new insights about the mechanisms that underpin PSFs and ultimately plant community assembly.},\n\tnumber = {2},\n\turldate = {2023-07-22},\n\tjournal = {Journal of Ecology},\n\tauthor = {Spitzer, Clydecia M. and Wardle, David A. and Lindahl, Björn D. and Sundqvist, Maja K. and Gundale, Michael J. and Fanin, Nicolas and Kardol, Paul},\n\tmonth = feb,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {arctic, fine root traits, functional ecology, fungi, plant–soil feedback, root economics spectrum, tundra ecosystems},\n\tpages = {466--478},\n}\n\n\n\n\n\n Abstract Plant?soil feedback (PSF) results from the influence of plants on the composition and abundance of various taxa and functional groups of soil micro-organisms, and their reciprocal effects on the plants. However, little is understood about the importance of fine root traits and root economic strategies in moderating microbial-driven PSF. We examined the relationships between PSF and 11 chemical and morphological root traits from 18 sub-arctic meadow plant species, as well as the soil microbial community composition which we characterized using phospholipid fatty acids (PLFAs) and high-throughput sequencing. We also investigated the importance of the root economics spectrum in influencing PSF, because it indicates plant below-ground economic strategies via trade-offs between resource acquisition and conservation. When we considered the entire root economics spectrum, we found that PSFs were more negative when root trait values were more acquisitive across the 18 species. In addition, PSF was more negative when values of root nitrogen content and root forks per root length were higher, and more positive when root dry matter content was higher. We additionally identified two fungal orders that were negatively related to PSF. However, we found no evidence that root traits influenced PSF through its relationship with these fungal orders. Synthesis. Our results provide evidence that for some fine root traits, the root economics spectrum and some fungal orders have an important role in influencing PSF. By investigating the roles of soil micro-organisms and fine root traits in driving PSF, this study enables us to better understand root trait?microbial linkages across species and therefore offers new insights about the mechanisms that underpin PSFs and ultimately plant community assembly.\n
\n\n\n\n \n\n \n \n \n \n \n \n Biomass, community composition and N:P recycling ratios of zooplankton in northern high-latitude lakes with contrasting levels of N deposition and dissolved organic carbon.\n \n \n \n \n\n\n \n Bergström, A.; Lau, D. C. P.; Isles, P. D. F.; Jonsson, A.; and Creed, I. F.\n\n\n \n\n\n\n Freshwater Biology, 67(9): 1508–1520. September 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{bergstrom_biomass_2022,\n\ttitle = {Biomass, community composition and {N}:{P} recycling ratios of zooplankton in northern high-latitude lakes with contrasting levels of {N} deposition and dissolved organic carbon},\n\tvolume = {67},\n\tissn = {0046-5070},\n\turl = {https://doi.org/10.1111/fwb.13956},\n\tdoi = {10.1111/fwb.13956},\n\tabstract = {Abstract Global changes are causing decreases in inorganic nitrogen (N) concentrations, increases in coloured dissolved organic carbon (DOC) concentrations, and decreases in dissolved inorganic N to total phosphorus ratios (DIN:TP) in northern lakes. The effects of these changes on phytoplankton and zooplankton biomass and the N:P recycling ratio of zooplankton remain unresolved. In 33 Swedish headwater lakes across subarctic-to-boreal gradients with different levels of N deposition (low N in the north [Västerbotten, boreal; Abisko, subarctic] vs. high N in the south [Värmland, boreal; Jämtland, subarctic]), we measured water chemistry, phytoplankton biomass (chlorophyll-a [Chl-a], Chl-a:TP), seston mineral quality (C:P, N:P), as well as zooplankton biomass, community composition, and C:N:P stoichiometry. We estimated nutrient imbalances and the N:P recycling ratios of zooplankton using ecological stoichiometry models. There was a large-scale gradient from low lake DIN and DIN:TP in the north to high DIN and DIN:TP in the south, with lower DIN:TP in lakes coinciding with higher DOC within each region. Lower lake DIN was associated with lower phytoplankton biomass (lower Chl-a:TP). Lower lake DIN:TP was associated with richer seston mineral quality (lower seston C:P and N:P) and higher zooplankton biomass. Zooplankton community composition differed in the north vs. south, with a dominance of N-requiring calanoid copepods with high N:P in the north and P-requiring cladocerans with low N:P in the south. Also, greater differences in zooplankton community composition were found between subarctic regions (with lower DOC) than between boreal regions (with higher DOC), suggesting that increases in lake DOC and associated declines in lake DIN:TP reduce differences in zooplankton community composition. The combination of lower lake DIN, higher lake DOC, and lower lake DIN:TP led to reduced zooplankton N:P recycling ratios, possibly by reducing seston N:P and/or by enhancing calanoid copepod dominance in the zooplankton community. Our findings suggest that the combination of declining N deposition and increasing lake browning in northern high-latitude lakes will reduce phytoplankton biomass, but will concurrently enhance seston mineral quality and probably also zooplankton biomass and their recycling efficiency of P relative to N.},\n\tnumber = {9},\n\turldate = {2023-07-22},\n\tjournal = {Freshwater Biology},\n\tauthor = {Bergström, Ann-Kristin and Lau, Danny C. P. and Isles, Peter D. F. and Jonsson, Anders and Creed, Irena F.},\n\tmonth = sep,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {C:N:P stoichiometry, biomass, community composition, plankton, subarctic-to-boreal},\n\tpages = {1508--1520},\n}\n\n\n\n\n\n Abstract Global changes are causing decreases in inorganic nitrogen (N) concentrations, increases in coloured dissolved organic carbon (DOC) concentrations, and decreases in dissolved inorganic N to total phosphorus ratios (DIN:TP) in northern lakes. The effects of these changes on phytoplankton and zooplankton biomass and the N:P recycling ratio of zooplankton remain unresolved. In 33 Swedish headwater lakes across subarctic-to-boreal gradients with different levels of N deposition (low N in the north [Västerbotten, boreal; Abisko, subarctic] vs. high N in the south [Värmland, boreal; Jämtland, subarctic]), we measured water chemistry, phytoplankton biomass (chlorophyll-a [Chl-a], Chl-a:TP), seston mineral quality (C:P, N:P), as well as zooplankton biomass, community composition, and C:N:P stoichiometry. We estimated nutrient imbalances and the N:P recycling ratios of zooplankton using ecological stoichiometry models. There was a large-scale gradient from low lake DIN and DIN:TP in the north to high DIN and DIN:TP in the south, with lower DIN:TP in lakes coinciding with higher DOC within each region. Lower lake DIN was associated with lower phytoplankton biomass (lower Chl-a:TP). Lower lake DIN:TP was associated with richer seston mineral quality (lower seston C:P and N:P) and higher zooplankton biomass. Zooplankton community composition differed in the north vs. south, with a dominance of N-requiring calanoid copepods with high N:P in the north and P-requiring cladocerans with low N:P in the south. Also, greater differences in zooplankton community composition were found between subarctic regions (with lower DOC) than between boreal regions (with higher DOC), suggesting that increases in lake DOC and associated declines in lake DIN:TP reduce differences in zooplankton community composition. The combination of lower lake DIN, higher lake DOC, and lower lake DIN:TP led to reduced zooplankton N:P recycling ratios, possibly by reducing seston N:P and/or by enhancing calanoid copepod dominance in the zooplankton community. Our findings suggest that the combination of declining N deposition and increasing lake browning in northern high-latitude lakes will reduce phytoplankton biomass, but will concurrently enhance seston mineral quality and probably also zooplankton biomass and their recycling efficiency of P relative to N.\n
\n\n\n\n \n\n \n \n \n \n \n \n Limited decadal growth of mountain birch saplings has minor impact on surrounding tundra vegetation.\n \n \n \n \n\n\n \n Scharn, R.; Negri, I. S.; Sundqvist, M. K.; Løkken, J. O.; Bacon, C. D.; Antonelli, A.; Hofgaard, A.; Nilsson, R. H.; and Björk, R. G.\n\n\n \n\n\n\n Ecology and Evolution, 12(6): e9028. June 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{scharn_limited_2022,\n\ttitle = {Limited decadal growth of mountain birch saplings has minor impact on surrounding tundra vegetation},\n\tvolume = {12},\n\tissn = {2045-7758},\n\turl = {https://doi.org/10.1002/ece3.9028},\n\tdoi = {10.1002/ece3.9028},\n\tabstract = {Abstract Temperatures over the Arctic region are increasing at three times the rate of the global average. Consequently, Arctic vegetation is changing and trees are encroaching into the tundra. In this study, we examine the establishment and growth of mountain birch (Betula pubescens ssp. tortuosa), which forms the treeline in subarctic Europe, and its impact on community composition across the treeline ecotone nearby Abisko, Sweden. Birch advancement along elevational gradients was studied by comparing data collected in 2016 with data collected 10 and 15?years previously. Species identity, cover, and phylogenetic relatedness were used to assess the impact of birch encroachment on community composition. Our results show that birch occurrence above the treeline did not affect plant community composition, probably owing to the observed lack of significant growth due to herbivore browsing, nitrogen limitation, or a reduction in snow cover. Independent of birch performance, the tundra community structure shifted toward a novel community dissimilar from the forest plant community found below the treeline. Taken together, our findings are explained by species-specific responses to climate change, rather than by a linear forest advance. Future treeline advancements are likely more restricted than previously expected.},\n\tnumber = {6},\n\turldate = {2023-07-22},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Scharn, Ruud and Negri, Isabel S. and Sundqvist, Maja K. and Løkken, Jørn O. and Bacon, Christine D. and Antonelli, Alexandre and Hofgaard, Annika and Nilsson, R. Henrik and Björk, Robert G.},\n\tmonth = jun,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Betula pubescens, Oroarctic, climate change, phylogenetic diversity, plant community structure, treeline advance},\n\tpages = {e9028},\n}\n\n\n\n\n\n Abstract Temperatures over the Arctic region are increasing at three times the rate of the global average. Consequently, Arctic vegetation is changing and trees are encroaching into the tundra. In this study, we examine the establishment and growth of mountain birch (Betula pubescens ssp. tortuosa), which forms the treeline in subarctic Europe, and its impact on community composition across the treeline ecotone nearby Abisko, Sweden. Birch advancement along elevational gradients was studied by comparing data collected in 2016 with data collected 10 and 15?years previously. Species identity, cover, and phylogenetic relatedness were used to assess the impact of birch encroachment on community composition. Our results show that birch occurrence above the treeline did not affect plant community composition, probably owing to the observed lack of significant growth due to herbivore browsing, nitrogen limitation, or a reduction in snow cover. Independent of birch performance, the tundra community structure shifted toward a novel community dissimilar from the forest plant community found below the treeline. Taken together, our findings are explained by species-specific responses to climate change, rather than by a linear forest advance. Future treeline advancements are likely more restricted than previously expected.\n
\n\n\n\n \n\n \n \n \n \n \n \n Hiking trails shift plant species' realized climatic niches and locally increase species richness.\n \n \n \n \n\n\n \n Wedegärtner, R. E. M.; Lembrechts, J. J.; van der Wal, R.; Barros, A.; Chauvin, A.; Janssens, I.; and Graae, B. J.\n\n\n \n\n\n\n Diversity and Distributions, 28(7): 1416–1429. July 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{wedegartner_hiking_2022,\n\ttitle = {Hiking trails shift plant species' realized climatic niches and locally increase species richness},\n\tvolume = {28},\n\tissn = {1366-9516},\n\turl = {https://doi.org/10.1111/ddi.13552},\n\tdoi = {10.1111/ddi.13552},\n\tabstract = {Abstract Aim The presence and use of trails may change plant species' realized climatic niches via modified abiotic and biotic conditions including propagule transport, allowing competition-pressed alpine species to expand their rear edges towards warmer locations and lowland species to extend their leading edges towards cooler locations. We investigated whether mountain trails indeed act as corridors for colonization and shift species' realized climatic niches, resulting in higher species richness in trailsides. Location Dovrefjell and Abisko area in the Scandes mountains of Norway and Sweden. Methods We surveyed plant community composition and disturbances along 16 hiking trails in summer 2018 (Dovrefjell) and 2019 (Abisko). We linked changes in species' realized climatic niches to their climatic optimum and variation in species richness to climate, trail effects and resident plant community characteristics. Results Plant species richness was on average 24\\% greater in trailside than in interior vegetation plots. Proximity to trails accounted for 9\\% and climatic harshness for 55\\% of variation in species richness explained in our model. Trailsides increased in richness, especially in relatively species-poor sites and close to introduction points (each accounting for 24\\% of variation in our model of species gains). Shifts in rear edges and optima of realized climatic niches along trails related to species' undisturbed climatic optimum, with alpine species being more likely to move into warmer locations. While some disturbance-associated species shifted their leading edges towards colder locations, contrary to expectations this was not the case for lowland species. Overall, shifts in climatic niches resulted in more species' niches overlapping in trailsides than in the interior vegetation. Main conclusion Trails can locally increase species richness by creating opportunities for colonizing species and weaker competitors. Because of prevailing disturbance, they may even provide opportunities for persistence and downward expansion of alpine species, aiding conservation efforts.},\n\tnumber = {7},\n\turldate = {2023-07-22},\n\tjournal = {Diversity and Distributions},\n\tauthor = {Wedegärtner, Ronja E. M. and Lembrechts, Jonas J. and van der Wal, René and Barros, Agustina and Chauvin, Aurélie and Janssens, Ilias and Graae, Bente Jessen},\n\tmonth = jul,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {alpine plants, biotic interactions, climate gradient, disturbance, mountain trails, realized niche, species range shifts},\n\tpages = {1416--1429},\n}\n\n\n\n\n\n Abstract Aim The presence and use of trails may change plant species' realized climatic niches via modified abiotic and biotic conditions including propagule transport, allowing competition-pressed alpine species to expand their rear edges towards warmer locations and lowland species to extend their leading edges towards cooler locations. We investigated whether mountain trails indeed act as corridors for colonization and shift species' realized climatic niches, resulting in higher species richness in trailsides. Location Dovrefjell and Abisko area in the Scandes mountains of Norway and Sweden. Methods We surveyed plant community composition and disturbances along 16 hiking trails in summer 2018 (Dovrefjell) and 2019 (Abisko). We linked changes in species' realized climatic niches to their climatic optimum and variation in species richness to climate, trail effects and resident plant community characteristics. Results Plant species richness was on average 24% greater in trailside than in interior vegetation plots. Proximity to trails accounted for 9% and climatic harshness for 55% of variation in species richness explained in our model. Trailsides increased in richness, especially in relatively species-poor sites and close to introduction points (each accounting for 24% of variation in our model of species gains). Shifts in rear edges and optima of realized climatic niches along trails related to species' undisturbed climatic optimum, with alpine species being more likely to move into warmer locations. While some disturbance-associated species shifted their leading edges towards colder locations, contrary to expectations this was not the case for lowland species. Overall, shifts in climatic niches resulted in more species' niches overlapping in trailsides than in the interior vegetation. Main conclusion Trails can locally increase species richness by creating opportunities for colonizing species and weaker competitors. Because of prevailing disturbance, they may even provide opportunities for persistence and downward expansion of alpine species, aiding conservation efforts.\n
\n\n\n\n \n\n \n \n \n \n \n \n Sodium hypochlorite as an oxidizing agent for removal of soil organic matter before microplastics analyses.\n \n \n \n \n\n\n \n Bottone, A.; Boily, J.; Shchukarev, A.; Andersson, P. L.; and Klaminder, J.\n\n\n \n\n\n\n Journal of Environmental Quality, 51(1): 112–122. January 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{bottone_sodium_2022,\n\ttitle = {Sodium hypochlorite as an oxidizing agent for removal of soil organic matter before microplastics analyses},\n\tvolume = {51},\n\tissn = {0047-2425},\n\turl = {https://doi.org/10.1002/jeq2.20321},\n\tdoi = {10.1002/jeq2.20321},\n\tabstract = {Abstract The omnipresence of microplastics (MPs) across Earth's surface has raised concerns about their environmental impact and created an urgent need for methods to identify them in complex soil and sedimentary matrices. However, detecting MPs in the O horizons of soils is difficult because plastic polymers share many physical and chemical properties with natural soil organic matter (SOM). In this study, we assessed whether sodium hypochlorite (NaOCl), a reagent that can oxidize SOM and simultaneously preserve mineral constituents, can be used for MP analysis and characterization in soil environments. In addition, we scrutinized how factors such as MP size, polymer type, extraction methods, and soil matrix affect the recovery of microplastic particles. We used both hydrophobic and density-dependent separation methods to assess the effects of our oxidation treatment on the recovery of MP. We observed that NaOCl effectively removed SOM without greatly altering the surface properties of resistant MP polymers (polypropylene, polylactic acid, low-density polyethylene, and polyethylene terephthalate), which were characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy after SOM removal. The NaOCl treatment caused some chlorination and formation of additional C?OH bonds on polymer surfaces, which likely contributed to the reduced efficiency of the hydrophobic-based (oil) extraction. We conclude that NaOCl treatment can improve detection of MPs in SOM-rich soil and that recovery of MPs from soils is influenced by MP size, polymer type, extraction method, and soil type, which makes it challenging to develop a universal analytical method.},\n\tnumber = {1},\n\turldate = {2023-07-22},\n\tjournal = {Journal of Environmental Quality},\n\tauthor = {Bottone, Anna and Boily, Jean-Francois and Shchukarev, Andrey and Andersson, Patrik L. and Klaminder, Jonatan},\n\tmonth = jan,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tpages = {112--122},\n}\n\n\n\n\n\n Abstract The omnipresence of microplastics (MPs) across Earth's surface has raised concerns about their environmental impact and created an urgent need for methods to identify them in complex soil and sedimentary matrices. However, detecting MPs in the O horizons of soils is difficult because plastic polymers share many physical and chemical properties with natural soil organic matter (SOM). In this study, we assessed whether sodium hypochlorite (NaOCl), a reagent that can oxidize SOM and simultaneously preserve mineral constituents, can be used for MP analysis and characterization in soil environments. In addition, we scrutinized how factors such as MP size, polymer type, extraction methods, and soil matrix affect the recovery of microplastic particles. We used both hydrophobic and density-dependent separation methods to assess the effects of our oxidation treatment on the recovery of MP. We observed that NaOCl effectively removed SOM without greatly altering the surface properties of resistant MP polymers (polypropylene, polylactic acid, low-density polyethylene, and polyethylene terephthalate), which were characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy after SOM removal. The NaOCl treatment caused some chlorination and formation of additional C?OH bonds on polymer surfaces, which likely contributed to the reduced efficiency of the hydrophobic-based (oil) extraction. We conclude that NaOCl treatment can improve detection of MPs in SOM-rich soil and that recovery of MPs from soils is influenced by MP size, polymer type, extraction method, and soil type, which makes it challenging to develop a universal analytical method.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global maps of soil temperature.\n \n \n \n \n\n\n \n Lembrechts, J. J.; van den Hoogen, J.; Aalto, J.; Ashcroft, M. B.; De Frenne, P.; Kemppinen, J.; Kopecký, M.; Luoto, M.; Maclean, I. M. D.; Crowther, T. W.; Bailey, J. J.; Haesen, S.; Klinges, D. H.; Niittynen, P.; Scheffers, B. R.; Van Meerbeek, K.; Aartsma, P.; Abdalaze, O.; Abedi, M.; Aerts, R.; Ahmadian, N.; Ahrends, A.; Alatalo, J. M.; Alexander, J. M.; Allonsius, C. N.; Altman, J.; Ammann, C.; Andres, C.; Andrews, C.; Ardö, J.; Arriga, N.; Arzac, A.; Aschero, V.; Assis, R. L.; Assmann, J. J.; Bader, M. Y.; Bahalkeh, K.; Barančok, P.; Barrio, I. C.; Barros, A.; Barthel, M.; Basham, E. W.; Bauters, M.; Bazzichetto, M.; Marchesini, L. B.; Bell, M. C.; Benavides, J. C.; Benito Alonso, J. L.; Berauer, B. J.; Bjerke, J. W.; Björk, R. G.; Björkman, M. P.; Björnsdóttir, K.; Blonder, B.; Boeckx, P.; Boike, J.; Bokhorst, S.; Brum, B. N. S.; Brůna, J.; Buchmann, N.; Buysse, P.; Camargo, J. L.; Campoe, O. C.; Candan, O.; Canessa, R.; Cannone, N.; Carbognani, M.; Carnicer, J.; Casanova-Katny, A.; Cesarz, S.; Chojnicki, B.; Choler, P.; Chown, S. L.; Cifuentes, E. F.; Čiliak, M.; Contador, T.; Convey, P.; Cooper, E. J.; Cremonese, E.; Curasi, S. R.; Curtis, R.; Cutini, M.; Dahlberg, C. J.; Daskalova, G. N.; de Pablo, M. A.; Della Chiesa, S.; Dengler, J.; Deronde, B.; Descombes, P.; Di Cecco, V.; Di Musciano, M.; Dick, J.; Dimarco, R. D.; Dolezal, J.; Dorrepaal, E.; Dušek, J.; Eisenhauer, N.; Eklundh, L.; Erickson, T. E.; Erschbamer, B.; Eugster, W.; Ewers, R. M.; Exton, D. A.; Fanin, N.; Fazlioglu, F.; Feigenwinter, I.; Fenu, G.; Ferlian, O.; Fernández Calzado, M. R.; Fernández-Pascual, E.; Finckh, M.; Higgens, R. F.; Forte, T. G. W.; Freeman, E. C.; Frei, E. R.; Fuentes-Lillo, E.; García, R. A.; García, M. B.; Géron, C.; Gharun, M.; Ghosn, D.; Gigauri, K.; Gobin, A.; Goded, I.; Goeckede, M.; Gottschall, F.; Goulding, K.; Govaert, S.; Graae, B. J.; Greenwood, S.; Greiser, C.; Grelle, A.; Guénard, B.; Guglielmin, M.; Guillemot, J.; Haase, P.; Haider, S.; Halbritter, A. H.; Hamid, M.; Hammerle, A.; Hampe, A.; Haugum, S. V.; Hederová, L.; Heinesch, B.; Helfter, C.; Hepenstrick, D.; Herberich, M.; Herbst, M.; Hermanutz, L.; Hik, D. S.; Hoffrén, R.; Homeier, J.; Hörtnagl, L.; Høye, T. T.; Hrbacek, F.; Hylander, K.; Iwata, H.; Jackowicz-Korczynski, M. A.; Jactel, H.; Järveoja, J.; Jastrzębowski, S.; Jentsch, A.; Jiménez, J. J.; Jónsdóttir, I. S.; Jucker, T.; Jump, A. S.; Juszczak, R.; Kanka, R.; Kašpar, V.; Kazakis, G.; Kelly, J.; Khuroo, A. A.; Klemedtsson, L.; Klisz, M.; Kljun, N.; Knohl, A.; Kobler, J.; Kollár, J.; Kotowska, M. M.; Kovács, B.; Kreyling, J.; Lamprecht, A.; Lang, S. I.; Larson, C.; Larson, K.; Laska, K.; le Maire, G.; Leihy, R. I.; Lens, L.; Liljebladh, B.; Lohila, A.; Lorite, J.; Loubet, B.; Lynn, J.; Macek, M.; Mackenzie, R.; Magliulo, E.; Maier, R.; Malfasi, F.; Máliš, F.; Man, M.; Manca, G.; Manco, A.; Manise, T.; Manolaki, P.; Marciniak, F.; Matula, R.; Mazzolari, A. C.; Medinets, S.; Medinets, V.; Meeussen, C.; Merinero, S.; Mesquita, R. d. C. G.; Meusburger, K.; Meysman, F. J. R.; Michaletz, S. T.; Milbau, A.; Moiseev, D.; Moiseev, P.; Mondoni, A.; Monfries, R.; Montagnani, L.; Moriana-Armendariz, M.; Morra di Cella, U.; Mörsdorf, M.; Mosedale, J. R.; Muffler, L.; Muñoz-Rojas, M.; Myers, J. A.; Myers-Smith, I. H.; Nagy, L.; Nardino, M.; Naujokaitis-Lewis, I.; Newling, E.; Nicklas, L.; Niedrist, G.; Niessner, A.; Nilsson, M. B.; Normand, S.; Nosetto, M. D.; Nouvellon, Y.; Nuñez, M. A.; Ogaya, R.; Ogée, J.; Okello, J.; Olejnik, J.; Olesen, J. E.; Opedal, Ø. H.; Orsenigo, S.; Palaj, A.; Pampuch, T.; Panov, A. V.; Pärtel, M.; Pastor, A.; Pauchard, A.; Pauli, H.; Pavelka, M.; Pearse, W. D.; Peichl, M.; Pellissier, L.; Penczykowski, R. M.; Penuelas, J.; Petit Bon, M.; Petraglia, A.; Phartyal, S. S.; Phoenix, G. K.; Pio, C.; Pitacco, A.; Pitteloud, C.; Plichta, R.; Porro, F.; Portillo-Estrada, M.; Poulenard, J.; Poyatos, R.; Prokushkin, A. S.; Puchalka, R.; Pușcaș, M.; Radujković, D.; Randall, K.; Ratier Backes, A.; Remmele, S.; Remmers, W.; Renault, D.; Risch, A. C.; Rixen, C.; Robinson, S. A.; Robroek, B. J. M.; Rocha, A. V.; Rossi, C.; Rossi, G.; Roupsard, O.; Rubtsov, A. V.; Saccone, P.; Sagot, C.; Sallo Bravo, J.; Santos, C. C.; Sarneel, J. M.; Scharnweber, T.; Schmeddes, J.; Schmidt, M.; Scholten, T.; Schuchardt, M.; Schwartz, N.; Scott, T.; Seeber, J.; Segalin de Andrade, A. C.; Seipel, T.; Semenchuk, P.; Senior, R. A.; Serra-Diaz, J. M.; Sewerniak, P.; Shekhar, A.; Sidenko, N. V.; Siebicke, L.; Siegwart Collier, L.; Simpson, E.; Siqueira, D. P.; Sitková, Z.; Six, J.; Smiljanic, M.; Smith, S. W.; Smith-Tripp, S.; Somers, B.; Sørensen, M. V.; Souza, J. J. L. L.; Souza, B. I.; Souza Dias, A.; Spasojevic, M. J.; Speed, J. D. M.; Spicher, F.; Stanisci, A.; Steinbauer, K.; Steinbrecher, R.; Steinwandter, M.; Stemkovski, M.; Stephan, J. G.; Stiegler, C.; Stoll, S.; Svátek, M.; Svoboda, M.; Tagesson, T.; Tanentzap, A. J.; Tanneberger, F.; Theurillat, J.; Thomas, H. J. D.; Thomas, A. D.; Tielbörger, K.; Tomaselli, M.; Treier, U. A.; Trouillier, M.; Turtureanu, P. D.; Tutton, R.; Tyystjärvi, V. A.; Ueyama, M.; Ujházy, K.; Ujházyová, M.; Uogintas, D.; Urban, A. V.; Urban, J.; Urbaniak, M.; Ursu, T.; Vaccari, F. P.; Van de Vondel, S.; van den Brink, L.; Van Geel, M.; Vandvik, V.; Vangansbeke, P.; Varlagin, A.; Veen, G. F.; Veenendaal, E.; Venn, S. E.; Verbeeck, H.; Verbrugggen, E.; Verheijen, F. G. A.; Villar, L.; Vitale, L.; Vittoz, P.; Vives-Ingla, M.; von Oppen, J.; Walz, J.; Wang, R.; Wang, Y.; Way, R. G.; Wedegärtner, R. E. M.; Weigel, R.; Wild, J.; Wilkinson, M.; Wilmking, M.; Wingate, L.; Winkler, M.; Wipf, S.; Wohlfahrt, G.; Xenakis, G.; Yang, Y.; Yu, Z.; Yu, K.; Zellweger, F.; Zhang, J.; Zhang, Z.; Zhao, P.; Ziemblińska, K.; Zimmermann, R.; Zong, S.; Zyryanov, V. I.; Nijs, I.; and Lenoir, J.\n\n\n \n\n\n\n Global Change Biology, 28(9): 3110–3144. May 2022.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{lembrechts_global_2022,\n\ttitle = {Global maps of soil temperature},\n\tvolume = {28},\n\tissn = {1354-1013},\n\turl = {https://doi.org/10.1111/gcb.16060},\n\tdoi = {10.1111/gcb.16060},\n\tabstract = {Abstract Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0?5 and 5?15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (?0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.},\n\tnumber = {9},\n\turldate = {2023-07-21},\n\tjournal = {Global Change Biology},\n\tauthor = {Lembrechts, Jonas J. and van den Hoogen, Johan and Aalto, Juha and Ashcroft, Michael B. and De Frenne, Pieter and Kemppinen, Julia and Kopecký, Martin and Luoto, Miska and Maclean, Ilya M. D. and Crowther, Thomas W. and Bailey, Joseph J. and Haesen, Stef and Klinges, David H. and Niittynen, Pekka and Scheffers, Brett R. and Van Meerbeek, Koenraad and Aartsma, Peter and Abdalaze, Otar and Abedi, Mehdi and Aerts, Rien and Ahmadian, Negar and Ahrends, Antje and Alatalo, Juha M. and Alexander, Jake M. and Allonsius, Camille Nina and Altman, Jan and Ammann, Christof and Andres, Christian and Andrews, Christopher and Ardö, Jonas and Arriga, Nicola and Arzac, Alberto and Aschero, Valeria and Assis, Rafael L. and Assmann, Jakob Johann and Bader, Maaike Y. and Bahalkeh, Khadijeh and Barančok, Peter and Barrio, Isabel C. and Barros, Agustina and Barthel, Matti and Basham, Edmund W. and Bauters, Marijn and Bazzichetto, Manuele and Marchesini, Luca Belelli and Bell, Michael C. and Benavides, Juan C. and Benito Alonso, José Luis and Berauer, Bernd J. and Bjerke, Jarle W. and Björk, Robert G. and Björkman, Mats P. and Björnsdóttir, Katrin and Blonder, Benjamin and Boeckx, Pascal and Boike, Julia and Bokhorst, Stef and Brum, Bárbara N. S. and Brůna, Josef and Buchmann, Nina and Buysse, Pauline and Camargo, José Luís and Campoe, Otávio C. and Candan, Onur and Canessa, Rafaella and Cannone, Nicoletta and Carbognani, Michele and Carnicer, Jofre and Casanova-Katny, Angélica and Cesarz, Simone and Chojnicki, Bogdan and Choler, Philippe and Chown, Steven L. and Cifuentes, Edgar F. and Čiliak, Marek and Contador, Tamara and Convey, Peter and Cooper, Elisabeth J. and Cremonese, Edoardo and Curasi, Salvatore R. and Curtis, Robin and Cutini, Maurizio and Dahlberg, C. Johan and Daskalova, Gergana N. and de Pablo, Miguel Angel and Della Chiesa, Stefano and Dengler, Jürgen and Deronde, Bart and Descombes, Patrice and Di Cecco, Valter and Di Musciano, Michele and Dick, Jan and Dimarco, Romina D. and Dolezal, Jiri and Dorrepaal, Ellen and Dušek, Jiří and Eisenhauer, Nico and Eklundh, Lars and Erickson, Todd E. and Erschbamer, Brigitta and Eugster, Werner and Ewers, Robert M. and Exton, Dan A. and Fanin, Nicolas and Fazlioglu, Fatih and Feigenwinter, Iris and Fenu, Giuseppe and Ferlian, Olga and Fernández Calzado, M. Rosa and Fernández-Pascual, Eduardo and Finckh, Manfred and Higgens, Rebecca Finger and Forte, T'ai G. W. and Freeman, Erika C. and Frei, Esther R. and Fuentes-Lillo, Eduardo and García, Rafael A. and García, María B. and Géron, Charly and Gharun, Mana and Ghosn, Dany and Gigauri, Khatuna and Gobin, Anne and Goded, Ignacio and Goeckede, Mathias and Gottschall, Felix and Goulding, Keith and Govaert, Sanne and Graae, Bente Jessen and Greenwood, Sarah and Greiser, Caroline and Grelle, Achim and Guénard, Benoit and Guglielmin, Mauro and Guillemot, Joannès and Haase, Peter and Haider, Sylvia and Halbritter, Aud H. and Hamid, Maroof and Hammerle, Albin and Hampe, Arndt and Haugum, Siri V. and Hederová, Lucia and Heinesch, Bernard and Helfter, Carole and Hepenstrick, Daniel and Herberich, Maximiliane and Herbst, Mathias and Hermanutz, Luise and Hik, David S. and Hoffrén, Raúl and Homeier, Jürgen and Hörtnagl, Lukas and Høye, Toke T. and Hrbacek, Filip and Hylander, Kristoffer and Iwata, Hiroki and Jackowicz-Korczynski, Marcin Antoni and Jactel, Hervé and Järveoja, Järvi and Jastrzębowski, Szymon and Jentsch, Anke and Jiménez, Juan J. and Jónsdóttir, Ingibjörg S. and Jucker, Tommaso and Jump, Alistair S. and Juszczak, Radoslaw and Kanka, Róbert and Kašpar, Vít and Kazakis, George and Kelly, Julia and Khuroo, Anzar A. and Klemedtsson, Leif and Klisz, Marcin and Kljun, Natascha and Knohl, Alexander and Kobler, Johannes and Kollár, Jozef and Kotowska, Martyna M. and Kovács, Bence and Kreyling, Juergen and Lamprecht, Andrea and Lang, Simone I. and Larson, Christian and Larson, Keith and Laska, Kamil and le Maire, Guerric and Leihy, Rachel I. and Lens, Luc and Liljebladh, Bengt and Lohila, Annalea and Lorite, Juan and Loubet, Benjamin and Lynn, Joshua and Macek, Martin and Mackenzie, Roy and Magliulo, Enzo and Maier, Regine and Malfasi, Francesco and Máliš, František and Man, Matěj and Manca, Giovanni and Manco, Antonio and Manise, Tanguy and Manolaki, Paraskevi and Marciniak, Felipe and Matula, Radim and Mazzolari, Ana Clara and Medinets, Sergiy and Medinets, Volodymyr and Meeussen, Camille and Merinero, Sonia and Mesquita, Rita de Cássia Guimarães and Meusburger, Katrin and Meysman, Filip J. R. and Michaletz, Sean T. and Milbau, Ann and Moiseev, Dmitry and Moiseev, Pavel and Mondoni, Andrea and Monfries, Ruth and Montagnani, Leonardo and Moriana-Armendariz, Mikel and Morra di Cella, Umberto and Mörsdorf, Martin and Mosedale, Jonathan R. and Muffler, Lena and Muñoz-Rojas, Miriam and Myers, Jonathan A. and Myers-Smith, Isla H. and Nagy, Laszlo and Nardino, Marianna and Naujokaitis-Lewis, Ilona and Newling, Emily and Nicklas, Lena and Niedrist, Georg and Niessner, Armin and Nilsson, Mats B. and Normand, Signe and Nosetto, Marcelo D. and Nouvellon, Yann and Nuñez, Martin A. and Ogaya, Romà and Ogée, Jérôme and Okello, Joseph and Olejnik, Janusz and Olesen, Jørgen Eivind and Opedal, Øystein H. and Orsenigo, Simone and Palaj, Andrej and Pampuch, Timo and Panov, Alexey V. and Pärtel, Meelis and Pastor, Ada and Pauchard, Aníbal and Pauli, Harald and Pavelka, Marian and Pearse, William D. and Peichl, Matthias and Pellissier, Loïc and Penczykowski, Rachel M. and Penuelas, Josep and Petit Bon, Matteo and Petraglia, Alessandro and Phartyal, Shyam S. and Phoenix, Gareth K. and Pio, Casimiro and Pitacco, Andrea and Pitteloud, Camille and Plichta, Roman and Porro, Francesco and Portillo-Estrada, Miguel and Poulenard, Jérôme and Poyatos, Rafael and Prokushkin, Anatoly S. and Puchalka, Radoslaw and Pușcaș, Mihai and Radujković, Dajana and Randall, Krystal and Ratier Backes, Amanda and Remmele, Sabine and Remmers, Wolfram and Renault, David and Risch, Anita C. and Rixen, Christian and Robinson, Sharon A. and Robroek, Bjorn J. M. and Rocha, Adrian V. and Rossi, Christian and Rossi, Graziano and Roupsard, Olivier and Rubtsov, Alexey V. and Saccone, Patrick and Sagot, Clotilde and Sallo Bravo, Jhonatan and Santos, Cinthya C. and Sarneel, Judith M. and Scharnweber, Tobias and Schmeddes, Jonas and Schmidt, Marius and Scholten, Thomas and Schuchardt, Max and Schwartz, Naomi and Scott, Tony and Seeber, Julia and Segalin de Andrade, Ana Cristina and Seipel, Tim and Semenchuk, Philipp and Senior, Rebecca A. and Serra-Diaz, Josep M. and Sewerniak, Piotr and Shekhar, Ankit and Sidenko, Nikita V. and Siebicke, Lukas and Siegwart Collier, Laura and Simpson, Elizabeth and Siqueira, David P. and Sitková, Zuzana and Six, Johan and Smiljanic, Marko and Smith, Stuart W. and Smith-Tripp, Sarah and Somers, Ben and Sørensen, Mia Vedel and Souza, José João L. L. and Souza, Bartolomeu Israel and Souza Dias, Arildo and Spasojevic, Marko J. and Speed, James D. M. and Spicher, Fabien and Stanisci, Angela and Steinbauer, Klaus and Steinbrecher, Rainer and Steinwandter, Michael and Stemkovski, Michael and Stephan, Jörg G. and Stiegler, Christian and Stoll, Stefan and Svátek, Martin and Svoboda, Miroslav and Tagesson, Torbern and Tanentzap, Andrew J. and Tanneberger, Franziska and Theurillat, Jean-Paul and Thomas, Haydn J. D. and Thomas, Andrew D. and Tielbörger, Katja and Tomaselli, Marcello and Treier, Urs Albert and Trouillier, Mario and Turtureanu, Pavel Dan and Tutton, Rosamond and Tyystjärvi, Vilna A. and Ueyama, Masahito and Ujházy, Karol and Ujházyová, Mariana and Uogintas, Domas and Urban, Anastasiya V. and Urban, Josef and Urbaniak, Marek and Ursu, Tudor-Mihai and Vaccari, Francesco Primo and Van de Vondel, Stijn and van den Brink, Liesbeth and Van Geel, Maarten and Vandvik, Vigdis and Vangansbeke, Pieter and Varlagin, Andrej and Veen, G. F. and Veenendaal, Elmar and Venn, Susanna E. and Verbeeck, Hans and Verbrugggen, Erik and Verheijen, Frank G. A. and Villar, Luis and Vitale, Luca and Vittoz, Pascal and Vives-Ingla, Maria and von Oppen, Jonathan and Walz, Josefine and Wang, Runxi and Wang, Yifeng and Way, Robert G. and Wedegärtner, Ronja E. M. and Weigel, Robert and Wild, Jan and Wilkinson, Matthew and Wilmking, Martin and Wingate, Lisa and Winkler, Manuela and Wipf, Sonja and Wohlfahrt, Georg and Xenakis, Georgios and Yang, Yan and Yu, Zicheng and Yu, Kailiang and Zellweger, Florian and Zhang, Jian and Zhang, Zhaochen and Zhao, Peng and Ziemblińska, Klaudia and Zimmermann, Reiner and Zong, Shengwei and Zyryanov, Viacheslav I. and Nijs, Ivan and Lenoir, Jonathan},\n\tmonth = may,\n\tyear = {2022},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, bioclimatic variables, global maps, microclimate, near-surface temperatures, soil temperature, soil-dwelling organisms, temperature offset, weather stations},\n\tpages = {3110--3144},\n}\n\n\n\n\n\n Abstract Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0?5 and 5?15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (?0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.\n
\n\n\n\n \n\n \n \n \n \n \n \n Functional microbial ecology in arctic soils: the need for a year-round perspective.\n \n \n \n \n\n\n \n Poppeliers, S. W M; Hefting, M.; Dorrepaal, E.; and Weedon, J. T\n\n\n \n\n\n\n FEMS Microbiology Ecology, 98(12): fiac134. December 2022.\n \n\n\n\n
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\n\n\n@article{poppeliers_functional_2022,\n\ttitle = {Functional microbial ecology in arctic soils: the need for a year-round perspective},\n\tvolume = {98},\n\tissn = {0168-6496},\n\turl = {https://doi.org/10.1093/femsec/fiac134},\n\tdoi = {10.1093/femsec/fiac134},\n\tabstract = {The microbial ecology of arctic and sub-arctic soils is an important aspect of the global carbon cycle, due to the sensitivity of the large soil carbon stocks to ongoing climate warming. These regions are characterized by strong climatic seasonality, but the emphasis of most studies on the short vegetation growing season could potentially limit our ability to predict year-round ecosystem functions. We compiled a database of studies from arctic, subarctic, and boreal environments that include sampling of microbial community and functions outside the growing season. We found that for studies comparing across seasons, in most environments, microbial biomass and community composition vary intra-annually, with the spring thaw period often identified by researchers as the most dynamic time of year. This seasonality of microbial communities will have consequences for predictions of ecosystem function under climate change if it results in: seasonality in process kinetics of microbe-mediated functions; intra-annual variation in the importance of different (a)biotic drivers; and/or potential temporal asynchrony between climate change-related perturbations and their corresponding effects. Future research should focus on (i) sampling throughout the entire year; (ii) linking these multi-season measures of microbial community composition with corresponding functional or physiological measurements to elucidate the temporal dynamics of the links between them; and (iii) identifying dominant biotic and abiotic drivers of intra-annual variation in different ecological contexts.},\n\tnumber = {12},\n\turldate = {2023-07-21},\n\tjournal = {FEMS Microbiology Ecology},\n\tauthor = {Poppeliers, Sanne W M and Hefting, Mariet and Dorrepaal, Ellen and Weedon, James T},\n\tmonth = dec,\n\tyear = {2022},\n\tkeywords = {\\#nosource, *Microbiota, *Soil, Arctic Regions, Carbon Cycle, Climate Change, bacteria, fluxes, fungi, seasonality, soil},\n\tpages = {fiac134},\n}\n\n\n\n\n\n The microbial ecology of arctic and sub-arctic soils is an important aspect of the global carbon cycle, due to the sensitivity of the large soil carbon stocks to ongoing climate warming. These regions are characterized by strong climatic seasonality, but the emphasis of most studies on the short vegetation growing season could potentially limit our ability to predict year-round ecosystem functions. We compiled a database of studies from arctic, subarctic, and boreal environments that include sampling of microbial community and functions outside the growing season. We found that for studies comparing across seasons, in most environments, microbial biomass and community composition vary intra-annually, with the spring thaw period often identified by researchers as the most dynamic time of year. This seasonality of microbial communities will have consequences for predictions of ecosystem function under climate change if it results in: seasonality in process kinetics of microbe-mediated functions; intra-annual variation in the importance of different (a)biotic drivers; and/or potential temporal asynchrony between climate change-related perturbations and their corresponding effects. Future research should focus on (i) sampling throughout the entire year; (ii) linking these multi-season measures of microbial community composition with corresponding functional or physiological measurements to elucidate the temporal dynamics of the links between them; and (iii) identifying dominant biotic and abiotic drivers of intra-annual variation in different ecological contexts.\n
\n\n\n\n \n\n \n \n \n \n \n \n Factors regulating the origin and magnitude of carbon dioxide emissions from high-latitude lakes.\n \n \n \n \n\n\n \n Verheijen, H.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2022.\n Publisher: Umeå University\n\n\n\n
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\n\n\n@phdthesis{verheijen_factors_2022,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Factors regulating the origin and magnitude of carbon dioxide emissions from high-latitude lakes},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-198962},\n\tabstract = {Lake ecosystems receive, transmit and process terrestrial carbon and thereby link terrestrial, aquatic and global carbon cycles. Most lakes evade CO2 to the atmosphere, but the annual magnitude of ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Verheijen, Hendricus},\n\tcollaborator = {Karlsson, Jan and Gudasz, Cristian and Seekell, David A. and Klaus, Marcus},\n\tyear = {2022},\n\tnote = {Publisher: Umeå University},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n Lake ecosystems receive, transmit and process terrestrial carbon and thereby link terrestrial, aquatic and global carbon cycles. Most lakes evade CO2 to the atmosphere, but the annual magnitude of ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Observation-constrained estimates of the global ocean carbon sink from Earth system models.\n \n \n \n \n\n\n \n Terhaar, J.; Frölicher, T. L.; and Joos, F.\n\n\n \n\n\n\n Biogeosciences, 19(18): 4431–4457. 2022.\n \n\n\n\n
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\n\n\n\n@article{terhaar_observation-constrained_2022,\n\ttitle = {Observation-constrained estimates of the global ocean carbon sink from {Earth} system models},\n\tvolume = {19},\n\turl = {https://bg.copernicus.org/articles/19/4431/2022/},\n\tdoi = {10.5194/bg-19-4431-2022},\n\tnumber = {18},\n\tjournal = {Biogeosciences},\n\tauthor = {Terhaar, J. and Frölicher, T. L. and Joos, F.},\n\tyear = {2022},\n\tkeywords = {\\#nosource},\n\tpages = {4431--4457},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Effects of conventionally treated and ozonated wastewater on the damselfly larva oxylipidome in response to on-site exposure.\n \n \n \n \n\n\n \n Späth, J.; Brodin, T.; Falås, P.; Niinipuu, M.; Lindberg, R.; Fick, J.; and Nording, M.\n\n\n \n\n\n\n Chemosphere, 309: 136604. December 2022.\n \n\n\n\n
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\n\n\n@article{spath_effects_2022,\n\ttitle = {Effects of conventionally treated and ozonated wastewater on the damselfly larva oxylipidome in response to on-site exposure},\n\tvolume = {309},\n\tissn = {0045-6535},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0045653522030971},\n\tdoi = {10.1016/j.chemosphere.2022.136604},\n\tabstract = {Pharmaceutical residues discharged through insufficiently treated or untreated wastewater enter aquatic environments, where they may adversely impact organisms such as aquatic invertebrates. Ozonation, an advanced wastewater treatment technique, has been successfully implemented to enhance the removal of a broad range of pharmaceuticals, however diverse byproducts and transformation products that are formed during the ozonation process make it difficult to predict how ozonated wastewater may affect aquatic biota. The aim of this study was to investigate effects on fatty acid metabolites, oxylipins, in a common invertebrate species, damselfly larvae, after on-site exposure to conventional wastewater treatment plant (WWTP) effluent and additionally ozonated effluent at a full-scale WWTP. Subsequent ozonation of the conventionally treated wastewater was assessed in terms of i) removal of pharmaceuticals and ii) potential sub-lethal effects on the oxylipidome. Northern damselfly (Coenagrion hastulatum) larvae were exposed for six days in the treatment plant facility to either conventional WWTP effluent or ozonated effluent and the effects on pharmaceutical levels and oxylipin levels were compared with those from tap water control exposure. Ozonation removed pharmaceuticals at an average removal efficiency of 67\\% (ozone dose of 0.49 g O3/g DOC). Of 38 pharmaceuticals detected in the effluent, 16 were removed to levels below the limit of quantification by ozonation. Levels of two oxylipins, 12(13)-EpODE and 15(16)-EpODE, were reduced in larvae exposed to the conventionally treated wastewater in comparison to the tap water control. 15(16)-EpODE was reduced in the larvae exposed to ozonated effluent in comparison to the tap water control. One oxylipin, 8-HETE, was significantly lower in larvae exposed to conventional WWTP effluent compared to ozonated effluent. In conclusion, the study provides proof-of-principle that damselfly larvae can be used on-site to test the impact of differentially treated wastewater.},\n\tjournal = {Chemosphere},\n\tauthor = {Späth, Jana and Brodin, Tomas and Falås, Per and Niinipuu, Mirva and Lindberg, Richard and Fick, Jerker and Nording, Malin},\n\tmonth = dec,\n\tyear = {2022},\n\tkeywords = {\\#nosource, Benthic invertebrate, Liquid chromatography tandem mass spectrometry, Metabolomics, Oxylipin, Ozonation, Sewage, Wastewater treatment plant},\n\tpages = {136604},\n}\n\n\n\n\n\n Pharmaceutical residues discharged through insufficiently treated or untreated wastewater enter aquatic environments, where they may adversely impact organisms such as aquatic invertebrates. Ozonation, an advanced wastewater treatment technique, has been successfully implemented to enhance the removal of a broad range of pharmaceuticals, however diverse byproducts and transformation products that are formed during the ozonation process make it difficult to predict how ozonated wastewater may affect aquatic biota. The aim of this study was to investigate effects on fatty acid metabolites, oxylipins, in a common invertebrate species, damselfly larvae, after on-site exposure to conventional wastewater treatment plant (WWTP) effluent and additionally ozonated effluent at a full-scale WWTP. Subsequent ozonation of the conventionally treated wastewater was assessed in terms of i) removal of pharmaceuticals and ii) potential sub-lethal effects on the oxylipidome. Northern damselfly (Coenagrion hastulatum) larvae were exposed for six days in the treatment plant facility to either conventional WWTP effluent or ozonated effluent and the effects on pharmaceutical levels and oxylipin levels were compared with those from tap water control exposure. Ozonation removed pharmaceuticals at an average removal efficiency of 67% (ozone dose of 0.49 g O3/g DOC). Of 38 pharmaceuticals detected in the effluent, 16 were removed to levels below the limit of quantification by ozonation. Levels of two oxylipins, 12(13)-EpODE and 15(16)-EpODE, were reduced in larvae exposed to the conventionally treated wastewater in comparison to the tap water control. 15(16)-EpODE was reduced in the larvae exposed to ozonated effluent in comparison to the tap water control. One oxylipin, 8-HETE, was significantly lower in larvae exposed to conventional WWTP effluent compared to ozonated effluent. In conclusion, the study provides proof-of-principle that damselfly larvae can be used on-site to test the impact of differentially treated wastewater.\n
\n\n\n\n \n\n \n \n \n \n \n \n Impacts of global change on primary production in northern lakes.\n \n \n \n \n\n\n \n Puts, I. C.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2022.\n Publisher: Umeå University\n\n\n\n
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\n\n\n@phdthesis{puts_impacts_2022,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Impacts of global change on primary production in northern lakes},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-194523},\n\tabstract = {Algae are primary producers, a major component of the aquatic foodweb, and changes in primary production affect aquatic ecology in general. Global changes such as warming, recovery of acidification ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Puts, Isolde Callisto},\n\tcollaborator = {Bergström, Ann-Kristin and Ask, Jenny},\n\tyear = {2022},\n\tnote = {Publisher: Umeå University},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n Algae are primary producers, a major component of the aquatic foodweb, and changes in primary production affect aquatic ecology in general. Global changes such as warming, recovery of acidification ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Vegetation type is an important predictor of the arctic summer land surface energy budget.\n \n \n \n \n\n\n \n Oehri, J.; Schaepman-Strub, G.; Kim, J.; Grysko, R.; Kropp, H.; Grünberg, I.; Zemlianskii, V.; Sonnentag, O.; Euskirchen, E. S.; Reji Chacko, M.; Muscari, G.; Blanken, P. D.; Dean, J. F.; di Sarra, A.; Harding, R. J.; Sobota, I.; Kutzbach, L.; Plekhanova, E.; Riihelä, A.; Boike, J.; Miller, N. B.; Beringer, J.; López-Blanco, E.; Stoy, P. C.; Sullivan, R. C.; Kejna, M.; Parmentier, F. W.; Gamon, J. A.; Mastepanov, M.; Wille, C.; Jackowicz-Korczynski, M.; Karger, D. N.; Quinton, W. L.; Putkonen, J.; van As, D.; Christensen, T. R.; Hakuba, M. Z.; Stone, R. S.; Metzger, S.; Vandecrux, B.; Frost, G. V.; Wild, M.; Hansen, B.; Meloni, D.; Domine, F.; te Beest, M.; Sachs, T.; Kalhori, A.; Rocha, A. V.; Williamson, S. N.; Morris, S.; Atchley, A. L.; Essery, R.; Runkle, B. R. K.; Holl, D.; Riihimaki, L. D.; Iwata, H.; Schuur, E. A. G.; Cox, C. J.; Grachev, A. A.; McFadden, J. P.; Fausto, R. S.; Göckede, M.; Ueyama, M.; Pirk, N.; de Boer, G.; Bret-Harte, M. S.; Leppäranta, M.; Steffen, K.; Friborg, T.; Ohmura, A.; Edgar, C. W.; Olofsson, J.; and Chambers, S. D.\n\n\n \n\n\n\n Nature Communications, 13(1): 6379. October 2022.\n \n\n\n\n
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\n\n\n@article{oehri_vegetation_2022,\n\ttitle = {Vegetation type is an important predictor of the arctic summer land surface energy budget},\n\tvolume = {13},\n\tissn = {2041-1723},\n\turl = {https://doi.org/10.1038/s41467-022-34049-3},\n\tdoi = {10.1038/s41467-022-34049-3},\n\tabstract = {Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994–2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm−2) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.},\n\tnumber = {1},\n\tjournal = {Nature Communications},\n\tauthor = {Oehri, Jacqueline and Schaepman-Strub, Gabriela and Kim, Jin-Soo and Grysko, Raleigh and Kropp, Heather and Grünberg, Inge and Zemlianskii, Vitalii and Sonnentag, Oliver and Euskirchen, Eugénie S. and Reji Chacko, Merin and Muscari, Giovanni and Blanken, Peter D. and Dean, Joshua F. and di Sarra, Alcide and Harding, Richard J. and Sobota, Ireneusz and Kutzbach, Lars and Plekhanova, Elena and Riihelä, Aku and Boike, Julia and Miller, Nathaniel B. and Beringer, Jason and López-Blanco, Efrén and Stoy, Paul C. and Sullivan, Ryan C. and Kejna, Marek and Parmentier, Frans-Jan W. and Gamon, John A. and Mastepanov, Mikhail and Wille, Christian and Jackowicz-Korczynski, Marcin and Karger, Dirk N. and Quinton, William L. and Putkonen, Jaakko and van As, Dirk and Christensen, Torben R. and Hakuba, Maria Z. and Stone, Robert S. and Metzger, Stefan and Vandecrux, Baptiste and Frost, Gerald V. and Wild, Martin and Hansen, Birger and Meloni, Daniela and Domine, Florent and te Beest, Mariska and Sachs, Torsten and Kalhori, Aram and Rocha, Adrian V. and Williamson, Scott N. and Morris, Sara and Atchley, Adam L. and Essery, Richard and Runkle, Benjamin R. K. and Holl, David and Riihimaki, Laura D. and Iwata, Hiroki and Schuur, Edward A. G. and Cox, Christopher J. and Grachev, Andrey A. and McFadden, Joseph P. and Fausto, Robert S. and Göckede, Mathias and Ueyama, Masahito and Pirk, Norbert and de Boer, Gijs and Bret-Harte, M. Syndonia and Leppäranta, Matti and Steffen, Konrad and Friborg, Thomas and Ohmura, Atsumu and Edgar, Colin W. and Olofsson, Johan and Chambers, Scott D.},\n\tmonth = oct,\n\tyear = {2022},\n\tkeywords = {\\#nosource},\n\tpages = {6379},\n}\n\n\n\n\n\n Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994–2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm−2) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.\n
\n\n\n\n \n\n \n \n \n \n \n \n Circum-Arctic distribution of chemical anti-herbivore compounds suggests biome-wide trade-off in defence strategies in Arctic shrubs.\n \n \n \n \n\n\n \n Lindén, E.; te Beest, M.; Abreu, I. N.; Moritz, T.; Sundqvist, M. K.; Barrio, I. C.; Boike, J.; Bryant, J. P.; Bråthen, K. A.; Buchwal, A.; Bueno, C. G.; Cuerrier, A.; Egelkraut, D. D.; Forbes, B. C.; Hallinger, M.; Heijmans, M.; Hermanutz, L.; Hik, D. S.; Hofgaard, A.; Holmgren, M.; Huebner, D. C.; Høye, T. T.; Jónsdóttir, I. S.; Kaarlejärvi, E.; Kissler, E.; Kumpula, T.; Limpens, J.; Myers-Smith, I. H.; Normand, S.; Post, E.; Rocha, A. V.; Schmidt, N. M.; Skarin, A.; Soininen, E. M.; Sokolov, A.; Sokolova, N.; Speed, J. D. M.; Street, L.; Tananaev, N.; Tremblay, J.; Urbanowicz, C.; Watts, D. A.; Zimmermann, H.; and Olofsson, J.\n\n\n \n\n\n\n Ecography, 2022(11): e06166. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/ecog.06166\n\n\n\n
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\n\n\n@article{linden_circum-arctic_2022,\n\ttitle = {Circum-{Arctic} distribution of chemical anti-herbivore compounds suggests biome-wide trade-off in defence strategies in {Arctic} shrubs},\n\tvolume = {2022},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/ecog.06166},\n\tdoi = {10.1111/ecog.06166},\n\tabstract = {Spatial variation in plant chemical defence towards herbivores can help us understand variation in herbivore top–down control of shrubs in the Arctic and possibly also shrub responses to global warming. Less defended, non-resinous shrubs could be more influenced by herbivores than more defended, resinous shrubs. However, sparse field measurements limit our current understanding of how much of the circum-Arctic variation in defence compounds is explained by taxa or defence functional groups (resinous/non-resinous). We measured circum-Arctic chemical defence and leaf digestibility in resinous (Betula glandulosa, B. nana ssp. exilis) and non-resinous (B. nana ssp. nana, B. pumila) shrub birches to see how they vary among and within taxa and functional groups. Using liquid chromatography–mass spectrometry (LC–MS) metabolomic analyses and in vitro leaf digestibility via incubation in cattle rumen fluid, we analysed defence composition and leaf digestibility in 128 samples from 44 tundra locations. We found biogeographical patterns in anti-herbivore defence where mean leaf triterpene concentrations and twig resin gland density were greater in resinous taxa and mean concentrations of condensing tannins were greater in non-resinous taxa. This indicates a biome-wide trade-off between triterpene- or tannin-dominated defences. However, we also found variations in chemical defence composition and resin gland density both within and among functional groups (resinous/non-resinous) and taxa, suggesting these categorisations only partly predict chemical herbivore defence. Complex tannins were the only defence compounds negatively related to in vitro digestibility, identifying this previously neglected tannin group as having a potential key role in birch anti-herbivore defence. We conclude that circum-Arctic variation in birch anti-herbivore defence can be partly derived from biogeographical distributions of birch taxa, although our detailed mapping of plant defence provides more information on this variation and can be used for better predictions of herbivore effects on Arctic vegetation.},\n\tnumber = {11},\n\tjournal = {Ecography},\n\tauthor = {Lindén, Elin and te Beest, Mariska and Abreu, Ilka N. and Moritz, Thomas and Sundqvist, Maja K. and Barrio, Isabel C. and Boike, Julia and Bryant, John P. and Bråthen, Kari Anne and Buchwal, Agata and Bueno, C. Guillermo and Cuerrier, Alain and Egelkraut, Dagmar D. and Forbes, Bruce C. and Hallinger, Martin and Heijmans, Monique and Hermanutz, Luise and Hik, David S. and Hofgaard, Annika and Holmgren, Milena and Huebner, Diane C. and Høye, Toke T. and Jónsdóttir, Ingibjörg S. and Kaarlejärvi, Elina and Kissler, Emilie and Kumpula, Timo and Limpens, Juul and Myers-Smith, Isla H. and Normand, Signe and Post, Eric and Rocha, Adrian V. and Schmidt, Niels Martin and Skarin, Anna and Soininen, Eeva M. and Sokolov, Aleksandr and Sokolova, Natalia and Speed, James D. M. and Street, Lorna and Tananaev, Nikita and Tremblay, Jean-Pierre and Urbanowicz, Christine and Watts, David A. and Zimmermann, Heike and Olofsson, Johan},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/ecog.06166},\n\tkeywords = {\\#nosource, Arctic, Betula, birch, herbivory, metabolomics, plant chemical defence, shrubs, tundra},\n\tpages = {e06166},\n}\n\n\n\n\n\n Spatial variation in plant chemical defence towards herbivores can help us understand variation in herbivore top–down control of shrubs in the Arctic and possibly also shrub responses to global warming. Less defended, non-resinous shrubs could be more influenced by herbivores than more defended, resinous shrubs. However, sparse field measurements limit our current understanding of how much of the circum-Arctic variation in defence compounds is explained by taxa or defence functional groups (resinous/non-resinous). We measured circum-Arctic chemical defence and leaf digestibility in resinous (Betula glandulosa, B. nana ssp. exilis) and non-resinous (B. nana ssp. nana, B. pumila) shrub birches to see how they vary among and within taxa and functional groups. Using liquid chromatography–mass spectrometry (LC–MS) metabolomic analyses and in vitro leaf digestibility via incubation in cattle rumen fluid, we analysed defence composition and leaf digestibility in 128 samples from 44 tundra locations. We found biogeographical patterns in anti-herbivore defence where mean leaf triterpene concentrations and twig resin gland density were greater in resinous taxa and mean concentrations of condensing tannins were greater in non-resinous taxa. This indicates a biome-wide trade-off between triterpene- or tannin-dominated defences. However, we also found variations in chemical defence composition and resin gland density both within and among functional groups (resinous/non-resinous) and taxa, suggesting these categorisations only partly predict chemical herbivore defence. Complex tannins were the only defence compounds negatively related to in vitro digestibility, identifying this previously neglected tannin group as having a potential key role in birch anti-herbivore defence. We conclude that circum-Arctic variation in birch anti-herbivore defence can be partly derived from biogeographical distributions of birch taxa, although our detailed mapping of plant defence provides more information on this variation and can be used for better predictions of herbivore effects on Arctic vegetation.\n
\n\n\n\n \n\n \n \n \n \n \n \n Experimentally increased snow depth affects high Arctic microarthropods inconsistently over two consecutive winters.\n \n \n \n \n\n\n \n Krab, E. J.; Lundin, E. J.; Coulson, S. J.; Dorrepaal, E.; and Cooper, E. J.\n\n\n \n\n\n\n Scientific Reports, 12(1): 18049. October 2022.\n \n\n\n\n
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\n\n\n@article{krab_experimentally_2022,\n\ttitle = {Experimentally increased snow depth affects high {Arctic} microarthropods inconsistently over two consecutive winters},\n\tvolume = {12},\n\tissn = {2045-2322},\n\turl = {https://doi.org/10.1038/s41598-022-22591-5},\n\tdoi = {10.1038/s41598-022-22591-5},\n\tabstract = {Climate change induced alterations to winter conditions may affect decomposer organisms controlling the vast carbon stores in northern soils. Soil microarthropods are particularly abundant decomposers in Arctic ecosystems. We studied whether increased snow depth affected microarthropods, and if effects were consistent over two consecutive winters. We sampled Collembola and soil mites from a snow accumulation experiment at Svalbard in early summer and used soil microclimatic data to explore to which aspects of winter climate microarthropods are most sensitive. Community densities differed substantially between years and increased snow depth had inconsistent effects. Deeper snow hardly affected microarthropods in 2015, but decreased densities and altered relative abundances of microarthropods and Collembola species after a milder winter in 2016. Although increased snow depth increased soil temperatures by 3.2 °C throughout the snow cover periods, the best microclimatic predictors of microarthropod density changes were spring soil temperature and snowmelt day. Our study shows that extrapolation of observations of decomposer responses to altered winter climate conditions to future scenarios should be avoided when communities are only sampled on a single occasion, since effects of longer-term gradual changes in winter climate may be obscured by inter-annual weather variability and natural variability in population sizes.},\n\tnumber = {1},\n\tjournal = {Scientific Reports},\n\tauthor = {Krab, Eveline J. and Lundin, Erik J. and Coulson, Stephen J. and Dorrepaal, Ellen and Cooper, Elisabeth J.},\n\tmonth = oct,\n\tyear = {2022},\n\tkeywords = {\\#nosource},\n\tpages = {18049},\n}\n\n\n\n\n\n Climate change induced alterations to winter conditions may affect decomposer organisms controlling the vast carbon stores in northern soils. Soil microarthropods are particularly abundant decomposers in Arctic ecosystems. We studied whether increased snow depth affected microarthropods, and if effects were consistent over two consecutive winters. We sampled Collembola and soil mites from a snow accumulation experiment at Svalbard in early summer and used soil microclimatic data to explore to which aspects of winter climate microarthropods are most sensitive. Community densities differed substantially between years and increased snow depth had inconsistent effects. Deeper snow hardly affected microarthropods in 2015, but decreased densities and altered relative abundances of microarthropods and Collembola species after a milder winter in 2016. Although increased snow depth increased soil temperatures by 3.2 °C throughout the snow cover periods, the best microclimatic predictors of microarthropod density changes were spring soil temperature and snowmelt day. Our study shows that extrapolation of observations of decomposer responses to altered winter climate conditions to future scenarios should be avoided when communities are only sampled on a single occasion, since effects of longer-term gradual changes in winter climate may be obscured by inter-annual weather variability and natural variability in population sizes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Groundwater discharge as a driver of methane emissions from Arctic lakes.\n \n \n \n \n\n\n \n Olid, C.; Rodellas, V.; Rocher-Ros, G.; Garcia-Orellana, J.; Diego-Feliu, M.; Alorda-Kleinglass, A.; Bastviken, D.; and Karlsson, J.\n\n\n \n\n\n\n Nature Communications, 13(1): 3667. June 2022.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{olid_groundwater_2022,\n\ttitle = {Groundwater discharge as a driver of methane emissions from {Arctic} lakes},\n\tvolume = {13},\n\tcopyright = {2022 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-022-31219-1},\n\tdoi = {10.1038/s41467-022-31219-1},\n\tabstract = {Lateral CH4 inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH4 production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH4 inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH4 emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH4 inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH4 production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH4 emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH4 inputs to lakes.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2023-07-20},\n\tjournal = {Nature Communications},\n\tauthor = {Olid, Carolina and Rodellas, Valentí and Rocher-Ros, Gerard and Garcia-Orellana, Jordi and Diego-Feliu, Marc and Alorda-Kleinglass, Aaron and Bastviken, David and Karlsson, Jan},\n\tmonth = jun,\n\tyear = {2022},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource, Carbon cycle, Climate-change impacts},\n\tpages = {3667},\n}\n\n\n\n\n\n Lateral CH4 inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH4 production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH4 inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH4 emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH4 inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH4 production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH4 emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH4 inputs to lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon dioxide limitation of benthic primary production in a boreal lake.\n \n \n \n \n\n\n \n Hamdan, M.; Karlsson, J.; Byström, P.; Al-Haidarey, M. J.; and Ask, J.\n\n\n \n\n\n\n Freshwater Biology, 67(10): 1752–1760. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13972\n\n\n\n
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\n\n\n@article{hamdan_carbon_2022,\n\ttitle = {Carbon dioxide limitation of benthic primary production in a boreal lake},\n\tvolume = {67},\n\tcopyright = {© 2022 The Authors. Freshwater Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2427},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.13972},\n\tdoi = {10.1111/fwb.13972},\n\tabstract = {Gross primary production (GPP) by benthic microalgae growing on soft sediments is an important contributor to lake productivity in many lakes world-wide. As benthic microalgae have access to nutrients in the sediment they have been regarded as primarily controlled by light, while the role of CO2 as a limiting factor for benthic GPP in lake ecosystems is largely unknown. In this study, we experimentally tested for CO2 limitation of benthic GPP by collecting littoral surface sediments, with associated benthic microalgae, from a typical boreal lake. Intact sediment cores were incubated at different depths (light conditions) after addition of dissolved inorganic (bicarbonate) or organic (DOC; glucose) carbon as direct and indirect sources of CO2, respectively. Benthic microalgal GPP was stimulated by both dissolved inorganic carbon and DOC additions at high, but not at low, light levels. This study shows that benthic microalgal GPP can be CO2-limited when light is not limiting and suggests that both direct (e.g., via groundwater inflow) and indirect (via mineralisation of DOC) CO2 supply can stimulate benthic GPP.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2023-07-20},\n\tjournal = {Freshwater Biology},\n\tauthor = {Hamdan, Mohammed and Karlsson, Jan and Byström, Pär and Al-Haidarey, Mohammed J. and Ask, Jenny},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13972},\n\tkeywords = {\\#nosource, CO2 limitation, benthic microalgal gross primary production, dissolved organic carbon, lakes, light limitation},\n\tpages = {1752--1760},\n}\n\n\n\n\n\n Gross primary production (GPP) by benthic microalgae growing on soft sediments is an important contributor to lake productivity in many lakes world-wide. As benthic microalgae have access to nutrients in the sediment they have been regarded as primarily controlled by light, while the role of CO2 as a limiting factor for benthic GPP in lake ecosystems is largely unknown. In this study, we experimentally tested for CO2 limitation of benthic GPP by collecting littoral surface sediments, with associated benthic microalgae, from a typical boreal lake. Intact sediment cores were incubated at different depths (light conditions) after addition of dissolved inorganic (bicarbonate) or organic (DOC; glucose) carbon as direct and indirect sources of CO2, respectively. Benthic microalgal GPP was stimulated by both dissolved inorganic carbon and DOC additions at high, but not at low, light levels. This study shows that benthic microalgal GPP can be CO2-limited when light is not limiting and suggests that both direct (e.g., via groundwater inflow) and indirect (via mineralisation of DOC) CO2 supply can stimulate benthic GPP.\n
\n\n\n\n \n\n \n \n \n \n \n \n Magnitude and Origin of CO2 Evasion From High-Latitude Lakes.\n \n \n \n \n\n\n \n Verheijen, H. A.; Klaus, M.; Seekell, D. A.; and Karlsson, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 127(6): e2021JG006768. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021JG006768\n\n\n\n
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\n\n\n@article{verheijen_magnitude_2022,\n\ttitle = {Magnitude and {Origin} of {CO2} {Evasion} {From} {High}-{Latitude} {Lakes}},\n\tvolume = {127},\n\tcopyright = {© 2022 The Authors.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JG006768},\n\tdoi = {10.1029/2021JG006768},\n\tabstract = {Lakes evade significant amounts of carbon dioxide (CO2) to the atmosphere; yet the magnitude and origin of the evasion are still poorly constrained. We quantified annual CO2 evasion and its origin (in-lake net ecosystem production vs. lateral inputs from terrestrial ecosystems) in 14 high-latitude lakes through high-frequency estimates of open water CO2 flux and ecosystem metabolism and inorganic carbon mass-balance before and after ice breakup. Annual CO2 evasion ranged from 1 to 25 g C m−2 yr−1 of which an average of 57\\% was evaded over a short period at ice-breakup. Annual internal CO2 production ranged from −6 to 21 g C m−2 yr−1, of which at least half was produced over winter. The contribution of internal versus external source contribution to annual CO2 evasion varied between lakes, ranging from fully internal to fully external with most lakes having over 75\\% of the evasion sustained through a single source. Overall, the study stresses the large variability in magnitude and control of CO2 evasion and suggests that environmental change impacts on CO2 evasion from high-latitude lakes are not uniform.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2023-07-20},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Verheijen, H. A. and Klaus, M. and Seekell, D. A. and Karlsson, J.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021JG006768},\n\tkeywords = {\\#nosource, carbon cycling, carbon dioxide flux, high-latitude, lakes, net ecosystem production, subarctic},\n\tpages = {e2021JG006768},\n}\n\n\n\n\n\n Lakes evade significant amounts of carbon dioxide (CO2) to the atmosphere; yet the magnitude and origin of the evasion are still poorly constrained. We quantified annual CO2 evasion and its origin (in-lake net ecosystem production vs. lateral inputs from terrestrial ecosystems) in 14 high-latitude lakes through high-frequency estimates of open water CO2 flux and ecosystem metabolism and inorganic carbon mass-balance before and after ice breakup. Annual CO2 evasion ranged from 1 to 25 g C m−2 yr−1 of which an average of 57% was evaded over a short period at ice-breakup. Annual internal CO2 production ranged from −6 to 21 g C m−2 yr−1, of which at least half was produced over winter. The contribution of internal versus external source contribution to annual CO2 evasion varied between lakes, ranging from fully internal to fully external with most lakes having over 75% of the evasion sustained through a single source. Overall, the study stresses the large variability in magnitude and control of CO2 evasion and suggests that environmental change impacts on CO2 evasion from high-latitude lakes are not uniform.\n
\n\n\n\n \n\n \n \n \n \n \n \n Depth and basin shape constrain ecosystem metabolism in lakes dominated by benthic primary producers.\n \n \n \n \n\n\n \n Klaus, M.; Verheijen, H. A.; Karlsson, J.; and Seekell, D. A.\n\n\n \n\n\n\n Limnology and Oceanography, 67(12): 2763–2778. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12236\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{klaus_depth_2022,\n\ttitle = {Depth and basin shape constrain ecosystem metabolism in lakes dominated by benthic primary producers},\n\tvolume = {67},\n\tcopyright = {© 2022 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.12236},\n\tdoi = {10.1002/lno.12236},\n\tabstract = {Metabolism is one of the most fundamental ecosystem processes, but the drivers of variation in metabolic rates among lakes dominated by benthic primary producers remain poorly constrained. Here, we report the magnitudes and potential drivers of whole-lake metabolism across 43 Swedish arctic–alpine lakes, based on the free-water diel oxygen technique with sondes deployed during the open-water season near the surface and bottom of the lakes. Gross primary production (GPP) and ecosystem respiration (R) were strongly coupled and ranged from 0.06 to 0.45 mg and 0.05 to 0.43 mg L−1 d−1 among lakes. On average, GPP and R decreased eightfold from relatively shallow to deep lakes (mean depth 0.5–10.9 m) and twofold from concave to convex lakes (mean depth: maximum depth 0.2–0.5). We attribute this to light limitation and shape-specific sensitivity of benthic GPP to disturbance by lake ice. Net ecosystem production (GPP-R) ranged from −0.09 to 0.14 mg L−1 d−1 and switched, on average, from positive to negative towards deeper lakes and lakes richer in dissolved organic carbon (DOC; 0.5–7.4 mg DOC L−1). Uncertainties in metabolism estimates were high (around one and three times mean R and GPP), especially in deep lakes with low insulation and diurnally variable wind speed. Our results confirm the role of DOC in stimulating net heterotrophy and highlight novel effects of lake shape on productivity in benthic-dominated lake ecosystems and its response to changes in lake ice cover.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2023-07-20},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Klaus, Marcus and Verheijen, Hendricus A. and Karlsson, Jan and Seekell, David A.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12236},\n\tkeywords = {\\#nosource},\n\tpages = {2763--2778},\n}\n\n\n\n\n\n Metabolism is one of the most fundamental ecosystem processes, but the drivers of variation in metabolic rates among lakes dominated by benthic primary producers remain poorly constrained. Here, we report the magnitudes and potential drivers of whole-lake metabolism across 43 Swedish arctic–alpine lakes, based on the free-water diel oxygen technique with sondes deployed during the open-water season near the surface and bottom of the lakes. Gross primary production (GPP) and ecosystem respiration (R) were strongly coupled and ranged from 0.06 to 0.45 mg and 0.05 to 0.43 mg L−1 d−1 among lakes. On average, GPP and R decreased eightfold from relatively shallow to deep lakes (mean depth 0.5–10.9 m) and twofold from concave to convex lakes (mean depth: maximum depth 0.2–0.5). We attribute this to light limitation and shape-specific sensitivity of benthic GPP to disturbance by lake ice. Net ecosystem production (GPP-R) ranged from −0.09 to 0.14 mg L−1 d−1 and switched, on average, from positive to negative towards deeper lakes and lakes richer in dissolved organic carbon (DOC; 0.5–7.4 mg DOC L−1). Uncertainties in metabolism estimates were high (around one and three times mean R and GPP), especially in deep lakes with low insulation and diurnally variable wind speed. Our results confirm the role of DOC in stimulating net heterotrophy and highlight novel effects of lake shape on productivity in benthic-dominated lake ecosystems and its response to changes in lake ice cover.\n
\n\n\n\n \n\n \n \n \n \n \n \n Towards a Monitoring Approach for Understanding Permafrost Degradation and Linked Subsidence in Arctic Peatlands.\n \n \n \n \n\n\n \n de la Barreda-Bautista, B.; Boyd, D. S.; Ledger, M.; Siewert, M. B.; Chandler, C.; Bradley, A. V.; Gee, D.; Large, D. J.; Olofsson, J.; Sowter, A.; and Sjögersten, S.\n\n\n \n\n\n\n Remote Sensing, 14(3): 444. January 2022.\n Number: 3 Publisher: Multidisciplinary Digital Publishing Institute\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{de_la_barreda-bautista_towards_2022,\n\ttitle = {Towards a {Monitoring} {Approach} for {Understanding} {Permafrost} {Degradation} and {Linked} {Subsidence} in {Arctic} {Peatlands}},\n\tvolume = {14},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\turl = {https://www.mdpi.com/2072-4292/14/3/444},\n\tdoi = {10.3390/rs14030444},\n\tabstract = {Permafrost thaw resulting from climate warming is threatening to release carbon from high latitude peatlands. The aim of this research was to determine subsidence rates linked to permafrost thaw in sub-Arctic peatlands in Sweden using historical orthophotographic (orthophotos), Unoccupied Aerial Vehicle (UAV), and Interferometric Synthetic Aperture Radar (InSAR) data. The orthophotos showed that the permafrost palsa on the study sites have been contracting in their areal extent, with the greatest rates of loss between 2002 and 2008. The surface motion estimated from differential digital elevation models from the UAV data showed high levels of subsidence (maximum of \\−25 cm between 2017 and 2020) around the edges of the raised palsa plateaus. The InSAR data analysis showed that raised palsa areas had the greatest subsidence rates, with maximum subsidence rates of 1.5 cm between 2017 and 2020; however, all wetland vegetation types showed subsidence. We suggest that the difference in spatial units associated with each sensor explains parts of the variation in the subsidence levels recorded. We conclude that InSAR was able to identify the areas most at risk of subsidence and that it can be used to investigate subsidence over large spatial extents, whereas UAV data can be used to better understand the dynamics of permafrost degradation at a local level. These findings underpin a monitoring approach for these peatlands.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2022-01-24},\n\tjournal = {Remote Sensing},\n\tauthor = {de la Barreda-Bautista, Betsabe and Boyd, Doreen S. and Ledger, Martha and Siewert, Matthias B. and Chandler, Chris and Bradley, Andrew V. and Gee, David and Large, David J. and Olofsson, Johan and Sowter, Andrew and Sjögersten, Sofie},\n\tmonth = jan,\n\tyear = {2022},\n\tnote = {Number: 3\nPublisher: Multidisciplinary Digital Publishing Institute},\n\tkeywords = {\\#nosource, InSAR, peatland, permafrost},\n\tpages = {444},\n}\n\n\n\n\n\n Permafrost thaw resulting from climate warming is threatening to release carbon from high latitude peatlands. The aim of this research was to determine subsidence rates linked to permafrost thaw in sub-Arctic peatlands in Sweden using historical orthophotographic (orthophotos), Unoccupied Aerial Vehicle (UAV), and Interferometric Synthetic Aperture Radar (InSAR) data. The orthophotos showed that the permafrost palsa on the study sites have been contracting in their areal extent, with the greatest rates of loss between 2002 and 2008. The surface motion estimated from differential digital elevation models from the UAV data showed high levels of subsidence (maximum of −25 cm between 2017 and 2020) around the edges of the raised palsa plateaus. The InSAR data analysis showed that raised palsa areas had the greatest subsidence rates, with maximum subsidence rates of 1.5 cm between 2017 and 2020; however, all wetland vegetation types showed subsidence. We suggest that the difference in spatial units associated with each sensor explains parts of the variation in the subsidence levels recorded. We conclude that InSAR was able to identify the areas most at risk of subsidence and that it can be used to investigate subsidence over large spatial extents, whereas UAV data can be used to better understand the dynamics of permafrost degradation at a local level. These findings underpin a monitoring approach for these peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Coupling plant litter quantity to a novel metric for litter quality explains C storage changes in a thawing permafrost peatland.\n \n \n \n \n\n\n \n Hough, M.; McCabe, S.; Vining, S. R.; Pickering Pedersen, E.; Wilson, R. M.; Lawrence, R.; Chang, K.; Bohrer, G.; Coordinators, T. I.; Riley, W. J.; Crill, P. M.; Varner, R. K.; Blazewicz, S. J.; Dorrepaal, E.; Tfaily, M. M.; Saleska, S. R.; and Rich, V. I.\n\n\n \n\n\n\n Global Change Biology, 28(3): 950–968. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15970\n\n\n\n
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\n\n\n@article{hough_coupling_2022,\n\ttitle = {Coupling plant litter quantity to a novel metric for litter quality explains {C} storage changes in a thawing permafrost peatland},\n\tvolume = {28},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15970},\n\tdoi = {10.1111/gcb.15970},\n\tabstract = {Permafrost thaw is a major potential feedback source to climate change as it can drive the increased release of greenhouse gases carbon dioxide (CO2) and methane (CH4). This carbon release from the decomposition of thawing soil organic material can be mitigated by increased net primary productivity (NPP) caused by warming, increasing atmospheric CO2, and plant community transition. However, the net effect on C storage also depends on how these plant community changes alter plant litter quantity, quality, and decomposition rates. Predicting decomposition rates based on litter quality remains challenging, but a promising new way forward is to incorporate measures of the energetic favorability to soil microbes of plant biomass decomposition. We asked how the variation in one such measure, the nominal oxidation state of carbon (NOSC), interacts with changing quantities of plant material inputs to influence the net C balance of a thawing permafrost peatland. We found: (1) Plant productivity (NPP) increased post-thaw, but instead of contributing to increased standing biomass, it increased plant biomass turnover via increased litter inputs to soil; (2) Plant litter thermodynamic favorability (NOSC) and decomposition rate both increased post-thaw, despite limited changes in bulk C:N ratios; (3) these increases caused the higher NPP to cycle more rapidly through both plants and soil, contributing to higher CO2 and CH4 fluxes from decomposition. Thus, the increased C-storage expected from higher productivity was limited and the high global warming potential of CH4 contributed a net positive warming effect. Although post-thaw peatlands are currently C sinks due to high NPP offsetting high CO2 release, this status is very sensitive to the plant community's litter input rate and quality. Integration of novel bioavailability metrics based on litter chemistry, including NOSC, into studies of ecosystem dynamics, is needed to improve the understanding of controls on arctic C stocks under continued ecosystem transition.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2022-01-20},\n\tjournal = {Global Change Biology},\n\tauthor = {Hough, Moira and McCabe, Samantha and Vining, S. Rose and Pickering Pedersen, Emily and Wilson, Rachel M. and Lawrence, Ryan and Chang, Kuang-Yu and Bohrer, Gil and Coordinators, The IsoGenie and Riley, William J. and Crill, Patrick M. and Varner, Ruth K. and Blazewicz, Steven J. and Dorrepaal, Ellen and Tfaily, Malak M. and Saleska, Scott R. and Rich, Virginia I.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15970},\n\tkeywords = {\\#nosource, C storage, NOSC, Stordalen Mire, decomposition, litter chemistry, peat, permafrost thaw, plant community change},\n\tpages = {950--968},\n}\n\n\n\n\n\n Permafrost thaw is a major potential feedback source to climate change as it can drive the increased release of greenhouse gases carbon dioxide (CO2) and methane (CH4). This carbon release from the decomposition of thawing soil organic material can be mitigated by increased net primary productivity (NPP) caused by warming, increasing atmospheric CO2, and plant community transition. However, the net effect on C storage also depends on how these plant community changes alter plant litter quantity, quality, and decomposition rates. Predicting decomposition rates based on litter quality remains challenging, but a promising new way forward is to incorporate measures of the energetic favorability to soil microbes of plant biomass decomposition. We asked how the variation in one such measure, the nominal oxidation state of carbon (NOSC), interacts with changing quantities of plant material inputs to influence the net C balance of a thawing permafrost peatland. We found: (1) Plant productivity (NPP) increased post-thaw, but instead of contributing to increased standing biomass, it increased plant biomass turnover via increased litter inputs to soil; (2) Plant litter thermodynamic favorability (NOSC) and decomposition rate both increased post-thaw, despite limited changes in bulk C:N ratios; (3) these increases caused the higher NPP to cycle more rapidly through both plants and soil, contributing to higher CO2 and CH4 fluxes from decomposition. Thus, the increased C-storage expected from higher productivity was limited and the high global warming potential of CH4 contributed a net positive warming effect. Although post-thaw peatlands are currently C sinks due to high NPP offsetting high CO2 release, this status is very sensitive to the plant community's litter input rate and quality. Integration of novel bioavailability metrics based on litter chemistry, including NOSC, into studies of ecosystem dynamics, is needed to improve the understanding of controls on arctic C stocks under continued ecosystem transition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global Patterns and Controls of Nutrient Immobilization on Decomposing Cellulose in Riverine Ecosystems.\n \n \n \n \n\n\n \n Costello, D. M.; Tiegs, S. D.; Boyero, L.; Canhoto, C.; Capps, K. A.; Danger, M.; Frost, P. C.; Gessner, M. O.; Griffiths, N. A.; Halvorson, H. M.; Kuehn, K. A.; Marcarelli, A. M.; Royer, T. V.; Mathie, D. M.; Albariño, R. J.; Arango, C. P.; Aroviita, J.; Baxter, C. V.; Bellinger, B. J.; Bruder, A.; Burdon, F. J.; Callisto, M.; Camacho, A.; Colas, F.; Cornut, J.; Crespo-Pérez, V.; Cross, W. F.; Derry, A. M.; Douglas, M. M.; Elosegi, A.; de Eyto, E.; Ferreira, V.; Ferriol, C.; Fleituch, T.; Follstad Shah, J. J.; Frainer, A.; Garcia, E. A.; García, L.; García, P. E.; Giling, D. P.; Gonzales-Pomar, R. K.; Graça, M. A. S.; Grossart, H.; Guérold, F.; Hepp, L. U.; Higgins, S. N.; Hishi, T.; Iñiguez-Armijos, C.; Iwata, T.; Kirkwood, A. E.; Koning, A. A.; Kosten, S.; Laudon, H.; Leavitt, P. R.; Lemes da Silva, A. L.; Leroux, S. J.; LeRoy, C. J.; Lisi, P. J.; Masese, F. O.; McIntyre, P. B.; McKie, B. G.; Medeiros, A. O.; Miliša, M.; Miyake, Y.; Mooney, R. J.; Muotka, T.; Nimptsch, J.; Paavola, R.; Pardo, I.; Parnikoza, I. Y.; Patrick, C. J.; Peeters, E. T. H. M.; Pozo, J.; Reid, B.; Richardson, J. S.; Rincón, J.; Risnoveanu, G.; Robinson, C. T.; Santamans, A. C.; Simiyu, G. M.; Skuja, A.; Smykla, J.; Sponseller, R. A.; Teixeira-de Mello, F.; Vilbaste, S.; Villanueva, V. D.; Webster, J. R.; Woelfl, S.; Xenopoulos, M. A.; Yates, A. G.; Yule, C. M.; Zhang, Y.; and Zwart, J. A.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 36(3): e2021GB007163. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GB007163\n\n\n\n
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\n\n\n@article{costello_global_2022,\n\ttitle = {Global {Patterns} and {Controls} of {Nutrient} {Immobilization} on {Decomposing} {Cellulose} in {Riverine} {Ecosystems}},\n\tvolume = {36},\n\tissn = {1944-9224},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021GB007163},\n\tdoi = {10.1029/2021GB007163},\n\tabstract = {Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2022-05-04},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Costello, David M. and Tiegs, Scott D. and Boyero, Luz and Canhoto, Cristina and Capps, Krista A. and Danger, Michael and Frost, Paul C. and Gessner, Mark O. and Griffiths, Natalie A. and Halvorson, Halvor M. and Kuehn, Kevin A. and Marcarelli, Amy M. and Royer, Todd V. and Mathie, Devan M. and Albariño, Ricardo J. and Arango, Clay P. and Aroviita, Jukka and Baxter, Colden V. and Bellinger, Brent J. and Bruder, Andreas and Burdon, Francis J. and Callisto, Marcos and Camacho, Antonio and Colas, Fanny and Cornut, Julien and Crespo-Pérez, Verónica and Cross, Wyatt F. and Derry, Alison M. and Douglas, Michael M. and Elosegi, Arturo and de Eyto, Elvira and Ferreira, Verónica and Ferriol, Carmen and Fleituch, Tadeusz and Follstad Shah, Jennifer J. and Frainer, André and Garcia, Erica A. and García, Liliana and García, Pavel E. and Giling, Darren P. and Gonzales-Pomar, R. Karina and Graça, Manuel A. S. and Grossart, Hans-Peter and Guérold, François and Hepp, Luiz U. and Higgins, Scott N. and Hishi, Takuo and Iñiguez-Armijos, Carlos and Iwata, Tomoya and Kirkwood, Andrea E. and Koning, Aaron A. and Kosten, Sarian and Laudon, Hjalmar and Leavitt, Peter R. and Lemes da Silva, Aurea L. and Leroux, Shawn J. and LeRoy, Carri J. and Lisi, Peter J. and Masese, Frank O. and McIntyre, Peter B. and McKie, Brendan G. and Medeiros, Adriana O. and Miliša, Marko and Miyake, Yo and Mooney, Robert J. and Muotka, Timo and Nimptsch, Jorge and Paavola, Riku and Pardo, Isabel and Parnikoza, Ivan Y. and Patrick, Christopher J. and Peeters, Edwin T. H. M. and Pozo, Jesus and Reid, Brian and Richardson, John S. and Rincón, José and Risnoveanu, Geta and Robinson, Christopher T. and Santamans, Anna C. and Simiyu, Gelas M. and Skuja, Agnija and Smykla, Jerzy and Sponseller, Ryan A. and Teixeira-de Mello, Franco and Vilbaste, Sirje and Villanueva, Verónica D. and Webster, Jackson R. and Woelfl, Stefan and Xenopoulos, Marguerite A. and Yates, Adam G. and Yule, Catherine M. and Zhang, Yixin and Zwart, Jacob A.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GB007163},\n\tkeywords = {\\#nosource, cotton strip assay, ecological stoichiometry, nitrogen, nutrient cycling, organic matter, phosphorus},\n\tpages = {e2021GB007163},\n}\n\n\n\n\n\n Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant-microbial linkages underpin carbon sequestration in contrasting mountain tundra vegetation types.\n \n \n \n \n\n\n \n Gavazov, K.; Canarini, A.; Jassey, V. E. J.; Mills, R.; Richter, A.; Sundqvist, M. K.; Väisänen, M.; Walker, T. W. N.; Wardle, D. A.; and Dorrepaal, E.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 165: 108530. February 2022.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{gavazov_plant-microbial_2022,\n\ttitle = {Plant-microbial linkages underpin carbon sequestration in contrasting mountain tundra vegetation types},\n\tvolume = {165},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071721004041},\n\tdoi = {10.1016/j.soilbio.2021.108530},\n\tabstract = {Tundra ecosystems hold large stocks of soil organic matter (SOM), likely due to low temperatures limiting rates of microbial SOM decomposition more than those of SOM accumulation from plant primary productivity and microbial necromass inputs. Here we test the hypotheses that distinct tundra vegetation types and their carbon supply to characteristic rhizosphere microbes determine SOM cycling independent of temperature. In the subarctic Scandes, we used a three-way factorial design with paired heath and meadow vegetation at each of two elevations, and with each combination of vegetation type and elevation subjected during one growing season to either ambient light (i.e., ambient plant productivity), or 95\\% shading (i.e., reduced plant productivity). We assessed potential above- and belowground ecosystem linkages by uni- and multivariate analyses of variance, and structural equation modelling. We observed direct coupling between tundra vegetation type and microbial community composition and function, which underpinned the ecosystem's potential for SOM storage. Greater primary productivity at low elevation and ambient light supported higher microbial biomass and nitrogen immobilisation, with lower microbial mass-specific enzymatic activity and SOM humification. Congruently, larger SOM at lower elevation and in heath sustained fungal-dominated microbial communities, which were less substrate-limited, and invested less into enzymatic SOM mineralisation, owing to a greater carbon-use efficiency (CUE). Our results highlight the importance of tundra plant community characteristics (i.e., productivity and vegetation type), via their effects on soil microbial community size, structure and physiology, as essential drivers of SOM turnover. The here documented concerted patterns in above- and belowground ecosystem functioning is strongly supportive of using plant community characteristics as surrogates for assessing tundra carbon storage potential and its evolution under climate and vegetation changes.},\n\tlanguage = {en},\n\turldate = {2022-01-20},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Gavazov, Konstantin and Canarini, Alberto and Jassey, Vincent E. J. and Mills, Robert and Richter, Andreas and Sundqvist, Maja K. and Väisänen, Maria and Walker, Tom W. N. and Wardle, David A. and Dorrepaal, Ellen},\n\tmonth = feb,\n\tyear = {2022},\n\tkeywords = {\\#nosource, Above- and belowground interactions, C:N stoichiometry, Carbon use efficiency, Elevation gradient, Microbial physiology, Primary productivity},\n\tpages = {108530},\n}\n\n\n\n\n\n Tundra ecosystems hold large stocks of soil organic matter (SOM), likely due to low temperatures limiting rates of microbial SOM decomposition more than those of SOM accumulation from plant primary productivity and microbial necromass inputs. Here we test the hypotheses that distinct tundra vegetation types and their carbon supply to characteristic rhizosphere microbes determine SOM cycling independent of temperature. In the subarctic Scandes, we used a three-way factorial design with paired heath and meadow vegetation at each of two elevations, and with each combination of vegetation type and elevation subjected during one growing season to either ambient light (i.e., ambient plant productivity), or 95% shading (i.e., reduced plant productivity). We assessed potential above- and belowground ecosystem linkages by uni- and multivariate analyses of variance, and structural equation modelling. We observed direct coupling between tundra vegetation type and microbial community composition and function, which underpinned the ecosystem's potential for SOM storage. Greater primary productivity at low elevation and ambient light supported higher microbial biomass and nitrogen immobilisation, with lower microbial mass-specific enzymatic activity and SOM humification. Congruently, larger SOM at lower elevation and in heath sustained fungal-dominated microbial communities, which were less substrate-limited, and invested less into enzymatic SOM mineralisation, owing to a greater carbon-use efficiency (CUE). Our results highlight the importance of tundra plant community characteristics (i.e., productivity and vegetation type), via their effects on soil microbial community size, structure and physiology, as essential drivers of SOM turnover. The here documented concerted patterns in above- and belowground ecosystem functioning is strongly supportive of using plant community characteristics as surrogates for assessing tundra carbon storage potential and its evolution under climate and vegetation changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon storage and burial in thermokarst lakes of permafrost peatlands.\n \n \n \n \n\n\n \n Manasypov, R. M.; Lim, A. G.; Krickov, I. V.; Shirokova, L. S.; Shevchenko, V. P.; Aliev, R. A.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Biogeochemistry, 159(1): 69–86. May 2022.\n \n\n\n\n
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\n\n\n@article{manasypov_carbon_2022,\n\ttitle = {Carbon storage and burial in thermokarst lakes of permafrost peatlands},\n\tvolume = {159},\n\tissn = {1573-515X},\n\turl = {https://doi.org/10.1007/s10533-022-00914-y},\n\tdoi = {10.1007/s10533-022-00914-y},\n\tabstract = {Thermokarst (thaw) lakes of the Western Siberian Lowland (WSL), the World´s largest permafrost peatland, contain important but poorly constrained stocks of organic carbon (OC) and nitrogen. These lakes are highly vulnerable to climate warming and permafrost thaw. The present work aims to quantify the OC and total nitrogen (TN) stocks and accumulation rates in sediments of 11 thermokarst lakes in the WSL across a permafrost gradient, from isolated to discontinuous and continuous permafrost. We found an increase in OC and TN stocks in lake sediments (0–30 cm) from the northern taiga with sporadic permafrost (285 Tg C and 10.5 Tg N) to the tundra zone with continuous permafrost (628 Tg C and 26 Tg N). The upper 30 cm thermokarst lake sediments of the permafrost-affected WSL store 1250 ± 35 Tg C and 50 ± 1.4 Tg N). The OC accumulation rates in thermokarst lake sediments ranged from 36 to 250 g C m−2 year−1, which is 5 to 10 times higher than C accumulation rates in peatlands of western Siberia. The total OC accumulation in lakes of WSL is 7.8 ± 0.7 Tg C year−1. This is about 24–47\\% of the C emission from the WSL thermokarst lakes, implying that it represents an important factor in the C budget to consider in order to understand impacts of climate change and permafrost thaw on the C cycle.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2022-05-04},\n\tjournal = {Biogeochemistry},\n\tauthor = {Manasypov, R. M. and Lim, A. G. and Krickov, I. V. and Shirokova, L. S. and Shevchenko, V. P. and Aliev, R. A. and Karlsson, J. and Pokrovsky, O. S.},\n\tmonth = may,\n\tyear = {2022},\n\tkeywords = {\\#nosource, Accumulation, Organic carbon, Sediments, Storage, Thermokarst lakes, Western Siberia},\n\tpages = {69--86},\n}\n\n\n\n\n\n Thermokarst (thaw) lakes of the Western Siberian Lowland (WSL), the World´s largest permafrost peatland, contain important but poorly constrained stocks of organic carbon (OC) and nitrogen. These lakes are highly vulnerable to climate warming and permafrost thaw. The present work aims to quantify the OC and total nitrogen (TN) stocks and accumulation rates in sediments of 11 thermokarst lakes in the WSL across a permafrost gradient, from isolated to discontinuous and continuous permafrost. We found an increase in OC and TN stocks in lake sediments (0–30 cm) from the northern taiga with sporadic permafrost (285 Tg C and 10.5 Tg N) to the tundra zone with continuous permafrost (628 Tg C and 26 Tg N). The upper 30 cm thermokarst lake sediments of the permafrost-affected WSL store 1250 ± 35 Tg C and 50 ± 1.4 Tg N). The OC accumulation rates in thermokarst lake sediments ranged from 36 to 250 g C m−2 year−1, which is 5 to 10 times higher than C accumulation rates in peatlands of western Siberia. The total OC accumulation in lakes of WSL is 7.8 ± 0.7 Tg C year−1. This is about 24–47% of the C emission from the WSL thermokarst lakes, implying that it represents an important factor in the C budget to consider in order to understand impacts of climate change and permafrost thaw on the C cycle.\n
\n\n\n\n \n\n \n \n \n \n \n \n An ecological and methodological assessment of benthic gross primary production in northern lakes.\n \n \n \n \n\n\n \n Puts, I. C.; Bergström, A.; Verheijen, H. A.; Norman, S.; and Ask, J.\n\n\n \n\n\n\n Ecosphere, 13(3): e3973. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ecs2.3973\n\n\n\n
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\n\n\n@article{puts_ecological_2022,\n\ttitle = {An ecological and methodological assessment of benthic gross primary production in northern lakes},\n\tvolume = {13},\n\tissn = {2150-8925},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ecs2.3973},\n\tdoi = {10.1002/ecs2.3973},\n\tabstract = {Benthic gross primary production (GPP) is often the most important part of aquatic food webs in northern lakes, which are gradually warming and receiving increased terrestrial colored dissolved organic carbon loadings due to global change. Yet, measurements of benthic GPP are fairly uncommon, and methods and unit dimensions of benthic GPP are unstandardized and rarely compared. In this study, we measured benthic GPP in 27 headwater lakes from three regions in northern Sweden and analyzed potential constraining drivers of benthic GPPz rates at discrete depths and estimates of benthic GPP averages across the whole lake, as well as across the littoral zone. We also compared in situ measurements of benthic GPP averages across the whole lake with modeled values using the “autotrophic structuring model.” We found that benthic GPPz rates were best explained by, and positively related to, available light (i.e., a function of depth and water color) and temperature. Benthic GPP averages across the whole lake, on the contrary, were best explained by the relative size of the littoral area, which is a measure that combines lake bathymetry and water color. The comparison between in situ measured and modeled estimates of benthic GPP averages across the whole lake revealed that (1) the autotrophic structuring model underestimates GPP at low values and overestimates GPP at high values compared with measured data, and that (2) measured values were related to temperature, which is not included as a variable in the autotrophic structuring model. Considering future predicted changes impacting northern latitude lakes, our results suggest that increased lake water temperatures can to some extent mitigate the negative impacts of reduced light availability from lake browning on benthic GPPz rates. The combined impact of these changes on benthic GPP averages across the whole lake will depend on, and be moderated by, lake bathymetry determining the relative size of the littoral area.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2022-05-04},\n\tjournal = {Ecosphere},\n\tauthor = {Puts, I. C. and Bergström, A.-K. and Verheijen, H. A. and Norman, S. and Ask, J.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ecs2.3973},\n\tkeywords = {\\#nosource, dissolved organic carbon, freshwater, gross primary production, littoral, soft sediments, upscaling},\n\tpages = {e3973},\n}\n\n\n\n\n\n Benthic gross primary production (GPP) is often the most important part of aquatic food webs in northern lakes, which are gradually warming and receiving increased terrestrial colored dissolved organic carbon loadings due to global change. Yet, measurements of benthic GPP are fairly uncommon, and methods and unit dimensions of benthic GPP are unstandardized and rarely compared. In this study, we measured benthic GPP in 27 headwater lakes from three regions in northern Sweden and analyzed potential constraining drivers of benthic GPPz rates at discrete depths and estimates of benthic GPP averages across the whole lake, as well as across the littoral zone. We also compared in situ measurements of benthic GPP averages across the whole lake with modeled values using the “autotrophic structuring model.” We found that benthic GPPz rates were best explained by, and positively related to, available light (i.e., a function of depth and water color) and temperature. Benthic GPP averages across the whole lake, on the contrary, were best explained by the relative size of the littoral area, which is a measure that combines lake bathymetry and water color. The comparison between in situ measured and modeled estimates of benthic GPP averages across the whole lake revealed that (1) the autotrophic structuring model underestimates GPP at low values and overestimates GPP at high values compared with measured data, and that (2) measured values were related to temperature, which is not included as a variable in the autotrophic structuring model. Considering future predicted changes impacting northern latitude lakes, our results suggest that increased lake water temperatures can to some extent mitigate the negative impacts of reduced light availability from lake browning on benthic GPPz rates. The combined impact of these changes on benthic GPP averages across the whole lake will depend on, and be moderated by, lake bathymetry determining the relative size of the littoral area.\n
\n\n\n\n \n\n \n \n \n \n \n \n Biochemical traits enhance the trait concept in Sphagnum ecology.\n \n \n \n \n\n\n \n Sytiuk, A.; Céréghino, R.; Hamard, S.; Delarue, F.; Dorrepaal, E.; Küttim, M.; Lamentowicz, M.; Pourrut, B.; Robroek, B. J. M.; Tuittila, E.; and Jassey, V. E. J.\n\n\n \n\n\n\n Oikos, 2022(4): e09119. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/oik.09119\n\n\n\n
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\n\n\n@article{sytiuk_biochemical_2022,\n\ttitle = {Biochemical traits enhance the trait concept in {Sphagnum} ecology},\n\tvolume = {2022},\n\tissn = {1600-0706},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.09119},\n\tdoi = {10.1111/oik.09119},\n\tabstract = {Sphagnum mosses are key to northern peatland carbon sequestration. They have a range of morphological and anatomical characteristics that allow them to cope with environmental stress. Sphagnum also produces a plethora of biochemicals that may prevent stress-induced cell-damage. However, the linkages between Sphagnum anatomical, morphological and biochemical traits (i.e. metabolites, pigments and antioxidant enzyme activities) are poorly known, neither are their joint responses to environmental change. Here, we quantify and link an array of Sphagnum anatomical, morphological and biochemical traits in five Sphagnum-dominated peatlands distributed along a latitudinal gradient in Europe, covering a range of regional and local environmental conditions. Sphagnum morphological and anatomical traits were intrinsically linked to Sphagnum metabolites and enzyme activities, and these relationships were driven by shared responses to local and regional environmental factors. More particularly, we found that Sphagnum traits can be grouped into four clusters related to growth, biomass, defense and water stress tolerance. We used regional and local environmental conditions data to further show that biochemicals and their specific linkages with some morphological traits describe dimensions of physiology not captured by anatomical and morphological traits alone. These results suggest that Sphagnum morphology and function is rooted in the metabolome, and that incorporating biochemicals into the functional trait space concept can enhance our mechanistic understanding and predictive power in Sphagnum ecology.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2022-05-04},\n\tjournal = {Oikos},\n\tauthor = {Sytiuk, Anna and Céréghino, Regis and Hamard, Samuel and Delarue, Frédéric and Dorrepaal, Ellen and Küttim, Martin and Lamentowicz, Mariusz and Pourrut, Bertrand and Robroek, Bjorn J. M. and Tuittila, Eeva-Stiina and Jassey, Vincent E. J.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/oik.09119},\n\tkeywords = {\\#nosource, Sphagnum, antioxidant enzyme activities, bryophytes, climate change, metabolites, peatlands},\n\tpages = {e09119},\n}\n\n\n\n\n\n Sphagnum mosses are key to northern peatland carbon sequestration. They have a range of morphological and anatomical characteristics that allow them to cope with environmental stress. Sphagnum also produces a plethora of biochemicals that may prevent stress-induced cell-damage. However, the linkages between Sphagnum anatomical, morphological and biochemical traits (i.e. metabolites, pigments and antioxidant enzyme activities) are poorly known, neither are their joint responses to environmental change. Here, we quantify and link an array of Sphagnum anatomical, morphological and biochemical traits in five Sphagnum-dominated peatlands distributed along a latitudinal gradient in Europe, covering a range of regional and local environmental conditions. Sphagnum morphological and anatomical traits were intrinsically linked to Sphagnum metabolites and enzyme activities, and these relationships were driven by shared responses to local and regional environmental factors. More particularly, we found that Sphagnum traits can be grouped into four clusters related to growth, biomass, defense and water stress tolerance. We used regional and local environmental conditions data to further show that biochemicals and their specific linkages with some morphological traits describe dimensions of physiology not captured by anatomical and morphological traits alone. These results suggest that Sphagnum morphology and function is rooted in the metabolome, and that incorporating biochemicals into the functional trait space concept can enhance our mechanistic understanding and predictive power in Sphagnum ecology.\n
\n\n\n\n \n\n \n \n \n \n \n \n Soil phosphorus forms show only minor changes across a 5000-year-old boreal wildfire chronosequence.\n \n \n \n \n\n\n \n Vincent, A. G.; Schleucher, J.; Giesler, R.; and Wardle, D. A.\n\n\n \n\n\n\n Biogeochemistry, 159(1): 15–32. May 2022.\n \n\n\n\n
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\n\n\n@article{vincent_soil_2022,\n\ttitle = {Soil phosphorus forms show only minor changes across a 5000-year-old boreal wildfire chronosequence},\n\tvolume = {159},\n\tissn = {1573-515X},\n\turl = {https://doi.org/10.1007/s10533-022-00910-2},\n\tdoi = {10.1007/s10533-022-00910-2},\n\tabstract = {Wildfire is the main disturbance in most boreal forests. In the prolonged absence of wildfire, ecosystem retrogression occurs, which is characterized by reduced productivity, plant biomass and belowground process rates. Previous evidence suggests that phosphorus (P) decreases during retrogression, but the mechanisms involved remain poorly understood. Here we use 1-D 31P and 2-D, 1H-31P NMR to characterize changes in humus P composition across a 5000 year post-fire chronosequence in northern Sweden, to understand why P availability declines during long term fire absence. Against expectations, humus P composition varied only modestly with increasing time since fire. Using a method to back-calculate the in situ soil organic P speciation, we found that it was dominated by biologically active compounds such as RNA (41\\%), phospholipids (28\\%) and DNA (22\\%). The concentration of DNA and pyrophosphate was 19\\% and 29\\% lower, respectively, on infrequently burnt than recently burnt islands, and the concentration of DNA, phospholipids and nucleotides was positively correlated with net primary productivity (NPP). Given the lack of evidence for the accumulation of “recalcitrant” P or a geochemical P sink, reductions in P availability during retrogression may be associated with impaired P cycling through slower decomposition rates, and increasing humus depth separating surface humus from P-rich mineral soil. Our findings align with observed negative relationships between NPP and organic P concentration across other chronosequences. They also suggest that changing fire regimes in the boreal zone could indirectly affect the P cycle through changes in NPP and soil microflora rather than through changes in humus P composition.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2022-05-04},\n\tjournal = {Biogeochemistry},\n\tauthor = {Vincent, Andrea G. and Schleucher, Jürgen and Giesler, Reiner and Wardle, David A.},\n\tmonth = may,\n\tyear = {2022},\n\tkeywords = {\\#nosource, Anthropogenic fire suppression, Arjeplog, Ecosystem retrogression, Fennoscandia, One-dimensional 31P NMR, Two-dimensional 1H, 31P NMR},\n\tpages = {15--32},\n}\n\n\n\n\n\n Wildfire is the main disturbance in most boreal forests. In the prolonged absence of wildfire, ecosystem retrogression occurs, which is characterized by reduced productivity, plant biomass and belowground process rates. Previous evidence suggests that phosphorus (P) decreases during retrogression, but the mechanisms involved remain poorly understood. Here we use 1-D 31P and 2-D, 1H-31P NMR to characterize changes in humus P composition across a 5000 year post-fire chronosequence in northern Sweden, to understand why P availability declines during long term fire absence. Against expectations, humus P composition varied only modestly with increasing time since fire. Using a method to back-calculate the in situ soil organic P speciation, we found that it was dominated by biologically active compounds such as RNA (41%), phospholipids (28%) and DNA (22%). The concentration of DNA and pyrophosphate was 19% and 29% lower, respectively, on infrequently burnt than recently burnt islands, and the concentration of DNA, phospholipids and nucleotides was positively correlated with net primary productivity (NPP). Given the lack of evidence for the accumulation of “recalcitrant” P or a geochemical P sink, reductions in P availability during retrogression may be associated with impaired P cycling through slower decomposition rates, and increasing humus depth separating surface humus from P-rich mineral soil. Our findings align with observed negative relationships between NPP and organic P concentration across other chronosequences. They also suggest that changing fire regimes in the boreal zone could indirectly affect the P cycle through changes in NPP and soil microflora rather than through changes in humus P composition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal variation in the coupling of microbial activity and leaf litter decomposition in a boreal stream network.\n \n \n \n \n\n\n \n Bastias, E.; Sponseller, R. A.; Bundschuh, M.; and Jonsson, M.\n\n\n \n\n\n\n Freshwater Biology, 67(5): 812–827. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13883\n\n\n\n
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\n\n\n@article{bastias_seasonal_2022,\n\ttitle = {Seasonal variation in the coupling of microbial activity and leaf litter decomposition in a boreal stream network},\n\tvolume = {67},\n\tissn = {1365-2427},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.13883},\n\tdoi = {10.1111/fwb.13883},\n\tabstract = {Most stream networks are characterised by spatial and temporal variability in the physico-chemical conditions that regulate microbial processing of particulate organic matter. How these patterns control the turnover of particulate organic matter via altered activity of leaf-associated microbes has rarely been studied in high-latitude landscapes, particularly throughout long (i.e., up to 6 months) ice- and snow-covered periods. We investigated development of fungal biomass, enzyme activity, microbial respiration, and birch leaf litter decomposition from autumn to early summer in 11 nested streams in a boreal catchment that encompass a gradient in wetland (mire) cover. We observed relatively low variability in decomposition rates across the network, despite differences in key physical and chemical variables (e.g. temperature, pH, and dissolved organic carbon [DOC] concentrations) over time and space. Microbial enzymatic activity and respiration were positively related to leaf litter decomposition rates during early stages of decomposition (i.e., up to c. 30\\% loss of initial ash-free dry mass). Thereafter, variation in microbial activity and respiration was decoupled from leaf litter mass loss, as enzymatic activity and respiration instead became positively related to DOC concentrations and upstream mire (wetland) cover among streams. Our results suggest that leaf-associated microbes increase their reliance on external sources of energy over time. This switch in resource use was more evident in streams with higher DOC concentration, which in boreal landscapes is largely determined by mire cover. Hence, variation in DOC concentration, linked to landscape configuration, or from intensified land use and climate change, could affect how different carbon sources are used by stream microbial communities, with consequences for overall carbon cycling in boreal headwaters.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2022-05-04},\n\tjournal = {Freshwater Biology},\n\tauthor = {Bastias, Elliot and Sponseller, Ryan A. and Bundschuh, Mirco and Jonsson, Micael},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13883},\n\tkeywords = {\\#nosource, Krycklan Catchment Study, birch, cellobiohydrolase, extracellular enzyme activity, leaf-use efficiency},\n\tpages = {812--827},\n}\n\n\n\n\n\n Most stream networks are characterised by spatial and temporal variability in the physico-chemical conditions that regulate microbial processing of particulate organic matter. How these patterns control the turnover of particulate organic matter via altered activity of leaf-associated microbes has rarely been studied in high-latitude landscapes, particularly throughout long (i.e., up to 6 months) ice- and snow-covered periods. We investigated development of fungal biomass, enzyme activity, microbial respiration, and birch leaf litter decomposition from autumn to early summer in 11 nested streams in a boreal catchment that encompass a gradient in wetland (mire) cover. We observed relatively low variability in decomposition rates across the network, despite differences in key physical and chemical variables (e.g. temperature, pH, and dissolved organic carbon [DOC] concentrations) over time and space. Microbial enzymatic activity and respiration were positively related to leaf litter decomposition rates during early stages of decomposition (i.e., up to c. 30% loss of initial ash-free dry mass). Thereafter, variation in microbial activity and respiration was decoupled from leaf litter mass loss, as enzymatic activity and respiration instead became positively related to DOC concentrations and upstream mire (wetland) cover among streams. Our results suggest that leaf-associated microbes increase their reliance on external sources of energy over time. This switch in resource use was more evident in streams with higher DOC concentration, which in boreal landscapes is largely determined by mire cover. Hence, variation in DOC concentration, linked to landscape configuration, or from intensified land use and climate change, could affect how different carbon sources are used by stream microbial communities, with consequences for overall carbon cycling in boreal headwaters.\n
\n\n\n\n \n\n \n \n \n \n \n \n The belowground growing season.\n \n \n \n \n\n\n \n Blume-Werry, G.\n\n\n \n\n\n\n Nature Climate Change, 12(1): 11–12. January 2022.\n Bandiera_abtest: a Cg_type: Nature Research Journals Number: 1 Primary_atype: News & Views Publisher: Nature Publishing Group Subject_term: Ecosystem ecology;Phenology Subject_term_id: ecosystem-ecology;phenology\n\n\n\n
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\n\n\n@article{blume-werry_belowground_2022,\n\ttitle = {The belowground growing season},\n\tvolume = {12},\n\tcopyright = {2021 Springer Nature Limited},\n\tissn = {1758-6798},\n\turl = {http://www.nature.com/articles/s41558-021-01243-y},\n\tdoi = {10.1038/s41558-021-01243-y},\n\tabstract = {As temperatures rise, plants unfold their leaves earlier in spring, but whether plant roots respond similarly is seldom quantified. Now, a meta-analysis suggests that leaf and root phenology do not respond to warming in the same way, even within the same plant types.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2022-01-17},\n\tjournal = {Nature Climate Change},\n\tauthor = {Blume-Werry, Gesche},\n\tmonth = jan,\n\tyear = {2022},\n\tnote = {Bandiera\\_abtest: a\nCg\\_type: Nature Research Journals\nNumber: 1\nPrimary\\_atype: News \\& Views\nPublisher: Nature Publishing Group\nSubject\\_term: Ecosystem ecology;Phenology\nSubject\\_term\\_id: ecosystem-ecology;phenology},\n\tkeywords = {\\#nosource, Ecosystem ecology, Phenology},\n\tpages = {11--12},\n}\n\n\n\n\n\n As temperatures rise, plants unfold their leaves earlier in spring, but whether plant roots respond similarly is seldom quantified. Now, a meta-analysis suggests that leaf and root phenology do not respond to warming in the same way, even within the same plant types.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Scaling Relationship for the Length of Tributaries to Lakes.\n \n \n \n \n\n\n \n Seekell, D.; Cael, B.; and Byström, P.\n\n\n \n\n\n\n Geophysical Research Letters, 49(7): e2022GL098183. 2022.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GL098183\n\n\n\n
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\n\n\n@article{seekell_scaling_2022,\n\ttitle = {The {Scaling} {Relationship} for the {Length} of {Tributaries} to {Lakes}},\n\tvolume = {49},\n\tissn = {1944-8007},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GL098183},\n\tdoi = {10.1029/2022GL098183},\n\tabstract = {Globally, the length of tributaries to lakes varies from 0 to more than 15,000 km, but scaling relationships describing this aspect of lake-river connectivity are lacking. In this study, we describe a simple theoretical scaling relationship for tributary length based on the principle of line intercepts of topographic features, and test this theory using data from Scandinavia. Tributary length increases by 73\\% for each doubling of lake area. This pattern reflects the relationship between catchment and lake area, and is modified by inlet frequency, junction angle, and lake shape—factors related to specific geologic and hydrologic processes. The theory is precise (r2 = 0.74), with low bias (mean error is 14\\% of mean tributary length) when the characteristic junction angle (∼76°) is estimated statistically. Our study bridges the gap between geomorphic and large-scale statistical relationships to provide simple rules for understanding complex patterns of lake-river connectivity.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2022-05-04},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Seekell, D. and Cael, B. and Byström, P.},\n\tyear = {2022},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2022GL098183},\n\tkeywords = {\\#nosource, hydrography, junction angle, lake-river connectivity, limnology, scaling},\n\tpages = {e2022GL098183},\n}\n\n\n\n\n\n Globally, the length of tributaries to lakes varies from 0 to more than 15,000 km, but scaling relationships describing this aspect of lake-river connectivity are lacking. In this study, we describe a simple theoretical scaling relationship for tributary length based on the principle of line intercepts of topographic features, and test this theory using data from Scandinavia. Tributary length increases by 73% for each doubling of lake area. This pattern reflects the relationship between catchment and lake area, and is modified by inlet frequency, junction angle, and lake shape—factors related to specific geologic and hydrologic processes. The theory is precise (r2 = 0.74), with low bias (mean error is 14% of mean tributary length) when the characteristic junction angle (∼76°) is estimated statistically. Our study bridges the gap between geomorphic and large-scale statistical relationships to provide simple rules for understanding complex patterns of lake-river connectivity.\n
\n\n\n\n \n\n \n \n \n \n \n \n Unravelling the Contribution of Turbulence and Bubbles to Air-Water Gas Exchange in Running Waters.\n \n \n \n \n\n\n \n Klaus, M.; Labasque, T.; Botter, G.; Durighetto, N.; and Schelker, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 127(3): e2021JG006520. 2022.\n Publisher: American Geophysical Union\n\n\n\n
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\n\n\n@article{klaus_unravelling_2022,\n\ttitle = {Unravelling the {Contribution} of {Turbulence} and {Bubbles} to {Air}-{Water} {Gas} {Exchange} in {Running} {Waters}},\n\tvolume = {127},\n\turl = {https://hal-insu.archives-ouvertes.fr/insu-03578679},\n\tdoi = {10.1029/2021JG006520},\n\tabstract = {Quantifying air-water gas exchange is critical for estimating greenhouse gas fluxes and metabolism in aquatic ecosystems. In high-energy streams, the gas exchange rate k is poorly constrained, due to an incomplete understanding of turbulence and bubble contributions to k. We performed a flume experiment with air bubble additions to evaluate the combined effects of turbulence and bubbles on k for helium, argon, xenon, and methane. We created contrasting hydraulic conditions by varying channel slope, bed roughness, water discharge, and bubble flux. We found that k increased from 1−4 to 17−66 m d-1 with increases in turbulence and bubble flux metrics. Mechanistic models that explicitly account for these metrics, as well as gas diffusivity and solubility agreed well with the data and indicated that bubble-mediated gas exchange accounted for 64−93\\% of k. Bubble contributions increased with bubble flux but were independent of gas type, as bubbles did not equilibrate with the water. This was evident through modelled bubble life and equilibration times inferred from bubble size distributions obtained from underwater sound spectra. Sound spectral properties correlated well with turbulence and bubble flux metrics. Our results demonstrate that i) mechanistic models can be applied to separate free surface- and bubble-mediated gas exchange in running waters, ii) bubble life and equilibration times are critical for accurate scaling of k between different gases, and iii) ambient sound spectra can be used to approximate contributions of turbulence and bubbles.},\n\tnumber = {3},\n\turldate = {2022-05-04},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Klaus, Marcus and Labasque, Thierry and Botter, G. and Durighetto, N. and Schelker, J.},\n\tyear = {2022},\n\tnote = {Publisher: American Geophysical Union},\n\tkeywords = {\\#nosource},\n\tpages = {e2021JG006520},\n}\n\n\n\n\n\n Quantifying air-water gas exchange is critical for estimating greenhouse gas fluxes and metabolism in aquatic ecosystems. In high-energy streams, the gas exchange rate k is poorly constrained, due to an incomplete understanding of turbulence and bubble contributions to k. We performed a flume experiment with air bubble additions to evaluate the combined effects of turbulence and bubbles on k for helium, argon, xenon, and methane. We created contrasting hydraulic conditions by varying channel slope, bed roughness, water discharge, and bubble flux. We found that k increased from 1−4 to 17−66 m d-1 with increases in turbulence and bubble flux metrics. Mechanistic models that explicitly account for these metrics, as well as gas diffusivity and solubility agreed well with the data and indicated that bubble-mediated gas exchange accounted for 64−93% of k. Bubble contributions increased with bubble flux but were independent of gas type, as bubbles did not equilibrate with the water. This was evident through modelled bubble life and equilibration times inferred from bubble size distributions obtained from underwater sound spectra. Sound spectral properties correlated well with turbulence and bubble flux metrics. Our results demonstrate that i) mechanistic models can be applied to separate free surface- and bubble-mediated gas exchange in running waters, ii) bubble life and equilibration times are critical for accurate scaling of k between different gases, and iii) ambient sound spectra can be used to approximate contributions of turbulence and bubbles.\n
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\n \n \n\n \n \n \n \n \n \n Permafrost Causes Unique Fine-Scale Spatial Variability Across Tundra Soils.\n \n \n \n \n\n\n \n Siewert, M. B.; Lantuit, H.; Richter, A.; and Hugelius, G.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 35(3): e2020GB006659. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020GB006659\n\n\n\n
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\n\n\n@article{siewert_permafrost_2021,\n\ttitle = {Permafrost {Causes} {Unique} {Fine}-{Scale} {Spatial} {Variability} {Across} {Tundra} {Soils}},\n\tvolume = {35},\n\tcopyright = {© 2021. The Authors.},\n\tissn = {1944-9224},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020GB006659},\n\tdoi = {10.1029/2020GB006659},\n\tabstract = {Spatial analysis in earth sciences is often based on the concept of spatial autocorrelation, expressed by W. Tobler as the first law of geography: “everything is related to everything else, but near things are more related than distant things.' Here, we show that subsurface soil properties in permafrost tundra terrain exhibit tremendous spatial variability. We describe the subsurface variability of soil organic carbon (SOC) and ground ice content from the centimeter to the landscape scale in three typical tundra terrain types common across the Arctic region. At the soil pedon scale, that is, from centimeters to 1–2 m, variability is caused by cryoturbation and affected by tussocks, hummocks and nonsorted circles. At the terrain scale, from meters to tens of meters, variability is caused by different generations of ice-wedges. Variability at the landscape scale, that is, ranging hundreds of meters, is associated with geomorphic disturbances and catenary shifts. The co-occurrence and overlap of different processes and landforms creates a spatial structure unique to permafrost environments. The coefficient of variation of SOC at the pedon scale (21\\%–73\\%) exceeds that found at terrain (17\\%–66\\%) and even landscape scale (24\\%–67\\%). Such high values for spatial variation are otherwise found at regional to continental scale. Clearly, permafrost soils do not conform to Tobler's law, but are among the most variable soils on Earth. This needs to be accounted for in mapping and predictions of the permafrost carbon feedbacks through various ecosystem processes. We conclude that scale deserves special attention in permafrost regions.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Siewert, M. B. and Lantuit, H. and Richter, A. and Hugelius, G.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020GB006659},\n\tkeywords = {\\#nosource, ground ice, permafrost, scale, soil organic carbon, tundra soils},\n\tpages = {e2020GB006659},\n}\n\n\n\n\n\n Spatial analysis in earth sciences is often based on the concept of spatial autocorrelation, expressed by W. Tobler as the first law of geography: “everything is related to everything else, but near things are more related than distant things.' Here, we show that subsurface soil properties in permafrost tundra terrain exhibit tremendous spatial variability. We describe the subsurface variability of soil organic carbon (SOC) and ground ice content from the centimeter to the landscape scale in three typical tundra terrain types common across the Arctic region. At the soil pedon scale, that is, from centimeters to 1–2 m, variability is caused by cryoturbation and affected by tussocks, hummocks and nonsorted circles. At the terrain scale, from meters to tens of meters, variability is caused by different generations of ice-wedges. Variability at the landscape scale, that is, ranging hundreds of meters, is associated with geomorphic disturbances and catenary shifts. The co-occurrence and overlap of different processes and landforms creates a spatial structure unique to permafrost environments. The coefficient of variation of SOC at the pedon scale (21%–73%) exceeds that found at terrain (17%–66%) and even landscape scale (24%–67%). Such high values for spatial variation are otherwise found at regional to continental scale. Clearly, permafrost soils do not conform to Tobler's law, but are among the most variable soils on Earth. This needs to be accounted for in mapping and predictions of the permafrost carbon feedbacks through various ecosystem processes. We conclude that scale deserves special attention in permafrost regions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Large and small herbivores have strong effects on tundra vegetation in Scandinavia and Alaska.\n \n \n \n \n\n\n \n Lindén, E.; Gough, L.; and Olofsson, J.\n\n\n \n\n\n\n Ecology and Evolution, 11(17): 12141–12152. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.7977\n\n\n\n
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\n\n\n@article{linden_large_2021,\n\ttitle = {Large and small herbivores have strong effects on tundra vegetation in {Scandinavia} and {Alaska}},\n\tvolume = {11},\n\tcopyright = {© 2021 The Authors. Ecology and Evolution published by John Wiley \\& Sons Ltd.},\n\tissn = {2045-7758},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.7977},\n\tdoi = {10.1002/ece3.7977},\n\tabstract = {Large and small mammalian herbivores are present in most vegetated areas in the Arctic and often have large impacts on plant community composition and ecosystem functioning. The relative importance of different herbivores and especially how their specific impact on the vegetation varies across the Arctic is however poorly understood. Here, we investigate how large and small herbivores influence vegetation density and plant community composition in four arctic vegetation types in Scandinavia and Alaska. We used a unique set of exclosures, excluding only large (reindeer and muskoxen) or all mammalian herbivores (also voles and lemmings) for at least 20 years. We found that mammalian herbivores in general decreased leaf area index, NDVI, and abundance of vascular plants in all four locations, even though the strength of the effect and which herbivore type caused these effects differed across locations. In three locations, herbivore presence caused contrasting plant communities, but not in the location with lowest productivity. Large herbivores had a negative effect on plant height, whereas small mammalian herbivores increased species diversity by decreasing dominance of the initially dominating plant species. Above- or belowground disturbances caused by herbivores were found to play an important role in shaping the vegetation in all locations. Synthesis: Based on these results, we conclude that both small and large mammalian herbivores influence vegetation in Scandinavia and Alaska in a similar way, some of which can mitigate effects of climate change. We also see important differences across locations, but these depend rather on local herbivore and plant community composition than large biogeographical differences among continents.},\n\tlanguage = {en},\n\tnumber = {17},\n\turldate = {2024-03-27},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Lindén, Elin and Gough, Laura and Olofsson, Johan},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.7977},\n\tkeywords = {\\#nosource, Arctic, Herbivores, diversity, exclosures, plant communities},\n\tpages = {12141--12152},\n}\n\n\n\n\n\n Large and small mammalian herbivores are present in most vegetated areas in the Arctic and often have large impacts on plant community composition and ecosystem functioning. The relative importance of different herbivores and especially how their specific impact on the vegetation varies across the Arctic is however poorly understood. Here, we investigate how large and small herbivores influence vegetation density and plant community composition in four arctic vegetation types in Scandinavia and Alaska. We used a unique set of exclosures, excluding only large (reindeer and muskoxen) or all mammalian herbivores (also voles and lemmings) for at least 20 years. We found that mammalian herbivores in general decreased leaf area index, NDVI, and abundance of vascular plants in all four locations, even though the strength of the effect and which herbivore type caused these effects differed across locations. In three locations, herbivore presence caused contrasting plant communities, but not in the location with lowest productivity. Large herbivores had a negative effect on plant height, whereas small mammalian herbivores increased species diversity by decreasing dominance of the initially dominating plant species. Above- or belowground disturbances caused by herbivores were found to play an important role in shaping the vegetation in all locations. Synthesis: Based on these results, we conclude that both small and large mammalian herbivores influence vegetation in Scandinavia and Alaska in a similar way, some of which can mitigate effects of climate change. We also see important differences across locations, but these depend rather on local herbivore and plant community composition than large biogeographical differences among continents.\n
\n\n\n\n \n\n \n \n \n \n \n \n From legacy effects of acid deposition in boreal streams to future environmental threats.\n \n \n \n \n\n\n \n Laudon, H.; Sponseller, R. A.; and Bishop, K.\n\n\n \n\n\n\n Environmental Research Letters, 16(1): 015007. January 2021.\n Publisher: IOP Publishing\n\n\n\n
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\n\n\n@article{laudon_legacy_2021,\n\ttitle = {From legacy effects of acid deposition in boreal streams to future environmental threats},\n\tvolume = {16},\n\tissn = {1748-9326},\n\turl = {https://dx.doi.org/10.1088/1748-9326/abd064},\n\tdoi = {10.1088/1748-9326/abd064},\n\tabstract = {Few environmental issues have resulted in such a heated policy-science controversy in Sweden as the 1990s acidification debate in the north of the country. The belief that exceptionally high stream acidity levels during hydrological events was caused by anthropogenic deposition resulted in a governmentally funded, multi-million dollar surface-water liming program. This program was heavily criticized by a large part of the scientific community arguing that the acidity of northern streams was primarily caused by naturally occurring organic acids. Here, we revisit the acid deposition legacy in northern Sweden two decades after the culmination of the controversy by examining the long-term water chemistry trends in the Svartberget/Krycklan research catchment that became a nexus for the Swedish debate. In this reference stream, trends in acidic episodes do show a modest recovery that matches declines in acid deposition to pre-industrial levels, although stream acidity continues to be overwhelmingly driven by organic acidity. Yet there are legacies of acid deposition related to calcium losses from soils, which are more pronounced than anticipated. Finally, assessment of these trends are becoming increasingly complicated by new changes and threats to water resources that must be recognized to avoid unnecessary, expensive, and potentially counterproductive measures to adapt and mitigate human influences. Here we make the argument that while the acidification era is ending, climate change, land-use transitions, and long-range transport of other contaminants warrant close monitoring in the decades to come.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Laudon, Hjalmar and Sponseller, Ryan A. and Bishop, Kevin},\n\tmonth = jan,\n\tyear = {2021},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {015007},\n}\n\n\n\n\n\n Few environmental issues have resulted in such a heated policy-science controversy in Sweden as the 1990s acidification debate in the north of the country. The belief that exceptionally high stream acidity levels during hydrological events was caused by anthropogenic deposition resulted in a governmentally funded, multi-million dollar surface-water liming program. This program was heavily criticized by a large part of the scientific community arguing that the acidity of northern streams was primarily caused by naturally occurring organic acids. Here, we revisit the acid deposition legacy in northern Sweden two decades after the culmination of the controversy by examining the long-term water chemistry trends in the Svartberget/Krycklan research catchment that became a nexus for the Swedish debate. In this reference stream, trends in acidic episodes do show a modest recovery that matches declines in acid deposition to pre-industrial levels, although stream acidity continues to be overwhelmingly driven by organic acidity. Yet there are legacies of acid deposition related to calcium losses from soils, which are more pronounced than anticipated. Finally, assessment of these trends are becoming increasingly complicated by new changes and threats to water resources that must be recognized to avoid unnecessary, expensive, and potentially counterproductive measures to adapt and mitigate human influences. Here we make the argument that while the acidification era is ending, climate change, land-use transitions, and long-range transport of other contaminants warrant close monitoring in the decades to come.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon emission from thermokarst lakes in NE European tundra.\n \n \n \n \n\n\n \n Zabelina, S. A.; Shirokova, L. S.; Klimov, S. I.; Chupakov, A. V.; Lim, A. G.; Polishchuk, Y. M.; Polishchuk, V. Y.; Bogdanov, A. N.; Muratov, I. N.; Guerin, F.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Limnology and Oceanography, 66(S1): S216–S230. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11560\n\n\n\n
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\n\n\n@article{zabelina_carbon_2021,\n\ttitle = {Carbon emission from thermokarst lakes in {NE} {European} tundra},\n\tvolume = {66},\n\tcopyright = {© 2020 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11560},\n\tdoi = {10.1002/lno.11560},\n\tabstract = {Emission of greenhouse gases (GHGs) from inland waters is recognized as highly important and an understudied part of the terrestrial carbon (C) biogeochemical cycle. These emissions are still poorly quantified in subarctic regions that contain vast amounts of surface C in permafrost peatlands. This is especially true in NE European peatlands, located within sporadic to discontinuous permafrost zones which are highly vulnerable to thaw. Initial measurements of C emissions from lentic waters of the Bolshezemelskaya Tundra (BZT; 200,000 km2) demonstrated sizable CO2 and CH4 concentrations and fluxes to the atmosphere in 98 depressions, thaw ponds, and thermokarst lakes ranging from 0.5 × 106 to 5 × 106 m2 in size. CO2 fluxes decreased by an order of magnitude as waterbody size increased by {\\textgreater} 3 orders of magnitude while CH4 fluxes showed large variability unrelated to lake size. By using a combination of Landsat-8 and GeoEye-1 images, we determined lakes cover 4\\% of BZT and thus calculated overall C emissions from lentic waters to be 3.8 ± 0.65 Tg C yr−1 (99\\% C-CO2, 1\\% C-CH4), which is two times higher than the lateral riverine export. Large lakes dominated GHG emissions whereas small thaw ponds had a minor contribution to overall water surface area and GHG emissions. These data suggest that, if permafrost thaw in NE Europe results in disappearance of large thermokarst lakes and formation of new small thaw ponds and depressions, GHG emissions from lentic waters in this region may decrease.},\n\tlanguage = {en},\n\tnumber = {S1},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Zabelina, Svetlana A. and Shirokova, Liudmila S. and Klimov, Sergey I. and Chupakov, Artem V. and Lim, Artem G. and Polishchuk, Yuri M. and Polishchuk, Vladimir Y. and Bogdanov, Alexander N. and Muratov, Ildar N. and Guerin, Frederic and Karlsson, Jan and Pokrovsky, Oleg S.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11560},\n\tkeywords = {\\#nosource},\n\tpages = {S216--S230},\n}\n\n\n\n\n\n Emission of greenhouse gases (GHGs) from inland waters is recognized as highly important and an understudied part of the terrestrial carbon (C) biogeochemical cycle. These emissions are still poorly quantified in subarctic regions that contain vast amounts of surface C in permafrost peatlands. This is especially true in NE European peatlands, located within sporadic to discontinuous permafrost zones which are highly vulnerable to thaw. Initial measurements of C emissions from lentic waters of the Bolshezemelskaya Tundra (BZT; 200,000 km2) demonstrated sizable CO2 and CH4 concentrations and fluxes to the atmosphere in 98 depressions, thaw ponds, and thermokarst lakes ranging from 0.5 × 106 to 5 × 106 m2 in size. CO2 fluxes decreased by an order of magnitude as waterbody size increased by \\textgreater 3 orders of magnitude while CH4 fluxes showed large variability unrelated to lake size. By using a combination of Landsat-8 and GeoEye-1 images, we determined lakes cover 4% of BZT and thus calculated overall C emissions from lentic waters to be 3.8 ± 0.65 Tg C yr−1 (99% C-CO2, 1% C-CH4), which is two times higher than the lateral riverine export. Large lakes dominated GHG emissions whereas small thaw ponds had a minor contribution to overall water surface area and GHG emissions. These data suggest that, if permafrost thaw in NE Europe results in disappearance of large thermokarst lakes and formation of new small thaw ponds and depressions, GHG emissions from lentic waters in this region may decrease.\n
\n\n\n\n \n\n \n \n \n \n \n \n Anthropogenic forcing of fish boldness and its impacts on ecosystem structure.\n \n \n \n \n\n\n \n Wang, W.; Xu, N.; Zhang, L.; Andersen, K. H.; and Klaminder, J.\n\n\n \n\n\n\n Global Change Biology, 27(6): 1239–1249. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15473\n\n\n\n
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\n\n\n@article{wang_anthropogenic_2021,\n\ttitle = {Anthropogenic forcing of fish boldness and its impacts on ecosystem structure},\n\tvolume = {27},\n\tcopyright = {© 2020 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15473},\n\tdoi = {10.1111/gcb.15473},\n\tabstract = {Modified fish behaviors in response to anthropogenic stressors, such as chemicals, microplastics, acoustic emissions and fisheries, are a debated driver of change in freshwater ecosystems and oceans. Our ability to judge the severity of observed behavioral responses is hampered by limited knowledge regarding how subtle behavior modifications in prey fish affect ecosystems. Here we show that anthropogenic stressors affecting fish boldness are not expected to cause population collapse, but rather elusive effects on fish length, population biomass, reproduction and ecosystem state shifts. We use a physiologically structured population model (three trophic levels), well fed with empirical data, to simulate how previously suggested alterations of fish boldness traits due to anthropogenic stressors affect ecosystem structure. Our results suggest that these stressors may cause ecosystem structure effects, such as skewed size distributions, reduced fish biomass and reduced reproduction success, by altering the foraging behavior of fish. However, the specific structure effects depend on where the boldness–shyness continuum change occurs and on the species-specific life stages. The model also highlights somewhat counterintuitive effects leading to possible extinction of predators when the foraging behavior of the prey is hampered. We conclude that anthropogenic forcing of fish behavior may be a hidden mechanism behind ecosystem structure changes in both freshwater and marine ecosystems.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Wang, Wei and Xu, Nuo and Zhang, Lai and Andersen, Ken H. and Klaminder, Jonatan},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15473},\n\tkeywords = {\\#nosource, aquatic ecosystem, behavioral trait, boldness alteration, life history, regime shift, size-structured population model},\n\tpages = {1239--1249},\n}\n\n\n\n\n\n Modified fish behaviors in response to anthropogenic stressors, such as chemicals, microplastics, acoustic emissions and fisheries, are a debated driver of change in freshwater ecosystems and oceans. Our ability to judge the severity of observed behavioral responses is hampered by limited knowledge regarding how subtle behavior modifications in prey fish affect ecosystems. Here we show that anthropogenic stressors affecting fish boldness are not expected to cause population collapse, but rather elusive effects on fish length, population biomass, reproduction and ecosystem state shifts. We use a physiologically structured population model (three trophic levels), well fed with empirical data, to simulate how previously suggested alterations of fish boldness traits due to anthropogenic stressors affect ecosystem structure. Our results suggest that these stressors may cause ecosystem structure effects, such as skewed size distributions, reduced fish biomass and reduced reproduction success, by altering the foraging behavior of fish. However, the specific structure effects depend on where the boldness–shyness continuum change occurs and on the species-specific life stages. The model also highlights somewhat counterintuitive effects leading to possible extinction of predators when the foraging behavior of the prey is hampered. We conclude that anthropogenic forcing of fish behavior may be a hidden mechanism behind ecosystem structure changes in both freshwater and marine ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Integrating carbon emission, accumulation and transport in inland waters to understand their role in the global carbon cycle.\n \n \n \n \n\n\n \n Vachon, D.; Sponseller, R. A.; and Karlsson, J.\n\n\n \n\n\n\n Global Change Biology, 27(4): 719–727. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15448\n\n\n\n
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\n\n\n@article{vachon_integrating_2021,\n\ttitle = {Integrating carbon emission, accumulation and transport in inland waters to understand their role in the global carbon cycle},\n\tvolume = {27},\n\tcopyright = {© 2020 The Authors. Global Change Biology published by John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15448},\n\tdoi = {10.1111/gcb.15448},\n\tabstract = {Inland waters receive a significant quantity of carbon (C) from land. The fate of this C during transit, whether it is emitted to the atmosphere, accumulated in sediments or transported to the ocean, can considerably reshape the landscape C balance. However, these different fates of terrestrial C are not independent but are instead linked via several catchment and aquatic processes. Thus, according to mass conservation, any environmental change inducing a shift in a particular C fate should come at the expense of at least one other fate. Nonetheless, studies that have investigated C emission, accumulation and transport concertedly are scarce, resulting in fragmented knowledge of the role of inland waters in the global C cycle. Here, we propose a framework to understand how different C fates in aquatic systems are interlinked and covary under environmental changes. First, to explore how C fates are currently distributed in streams, rivers, reservoirs and lakes, we compiled data from the literature and show that ‘C fate allocation’ varies widely both within and among inland water systems types. Secondly, we developed a framework that integrates C fates in any inland water system by identifying the key processes underlying their linkages. Our framework places the partitioning between the different C forms, and how this is controlled by export from land, internal transformations and hydrology, as central to understanding C fate allocation. We argue that, by focusing on a single fate, studies could risk drawing misleading conclusions regarding how environmental changes will alter the role of inland waters in the global C cycle. Our framework thus allows us to holistically assess the consequences of such changes on coupled C fluxes, setting a foundation for understanding the contemporary and future fate of land-derived C in inland water systems.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Vachon, Dominic and Sponseller, Ryan A. and Karlsson, Jan},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15448},\n\tkeywords = {\\#nosource, carbon cycle, conceptual framework, coupled fluxes, global change, inland waters, terrestrial carbon fate},\n\tpages = {719--727},\n}\n\n\n\n\n\n Inland waters receive a significant quantity of carbon (C) from land. The fate of this C during transit, whether it is emitted to the atmosphere, accumulated in sediments or transported to the ocean, can considerably reshape the landscape C balance. However, these different fates of terrestrial C are not independent but are instead linked via several catchment and aquatic processes. Thus, according to mass conservation, any environmental change inducing a shift in a particular C fate should come at the expense of at least one other fate. Nonetheless, studies that have investigated C emission, accumulation and transport concertedly are scarce, resulting in fragmented knowledge of the role of inland waters in the global C cycle. Here, we propose a framework to understand how different C fates in aquatic systems are interlinked and covary under environmental changes. First, to explore how C fates are currently distributed in streams, rivers, reservoirs and lakes, we compiled data from the literature and show that ‘C fate allocation’ varies widely both within and among inland water systems types. Secondly, we developed a framework that integrates C fates in any inland water system by identifying the key processes underlying their linkages. Our framework places the partitioning between the different C forms, and how this is controlled by export from land, internal transformations and hydrology, as central to understanding C fate allocation. We argue that, by focusing on a single fate, studies could risk drawing misleading conclusions regarding how environmental changes will alter the role of inland waters in the global C cycle. Our framework thus allows us to holistically assess the consequences of such changes on coupled C fluxes, setting a foundation for understanding the contemporary and future fate of land-derived C in inland water systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Metabolism overrides photo-oxidation in CO2 dynamics of Arctic permafrost streams.\n \n \n \n \n\n\n \n Rocher-Ros, G.; Harms, T. K.; Sponseller, R. A.; Väisänen, M.; Mörth, C.; and Giesler, R.\n\n\n \n\n\n\n Limnology and Oceanography, 66(S1): S169–S181. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11564\n\n\n\n
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\n\n\n@article{rocher-ros_metabolism_2021,\n\ttitle = {Metabolism overrides photo-oxidation in {CO2} dynamics of {Arctic} permafrost streams},\n\tvolume = {66},\n\tcopyright = {© 2020 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11564},\n\tdoi = {10.1002/lno.11564},\n\tabstract = {Global warming is enhancing the mobilization of organic carbon (C) from Arctic soils into streams, where it can be mineralized to CO2 and released to the atmosphere. Abiotic photo-oxidation might drive C mineralization, but this process has not been quantitatively integrated with biological processes that also influence CO2 dynamics in aquatic ecosystems. We measured CO2 concentrations and the isotopic composition of dissolved inorganic C (δ13CDIC) at diel resolution in two Arctic streams, and coupled this with whole-system metabolism estimates to assess the effect of biotic and abiotic processes on stream C dynamics. CO2 concentrations consistently decreased from night to day, a pattern counter to the hypothesis that photo-oxidation is the dominant source of CO2. Instead, the observed decrease in CO2 during daytime was explained by photosynthetic rates, which were strongly correlated with diurnal changes in δ13CDIC values. However, on days when modeled photosynthetic rates were near zero, there was still a significant diel change in δ13CDIC values, suggesting that metabolic estimates are partly masked by O2 consumption from photo-oxidation. Our results suggest that 6–12 mmol CO2-C m−2 d−1 may be generated from photo-oxidation, a range that corresponds well to previous laboratory measurements. Moreover, ecosystem respiration rates were 10 times greater than published photo-oxidation rates for these Arctic streams, and accounted for 33–80\\% of total CO2 evasion. Our results suggest that metabolic activity is the dominant process for CO2 production in Arctic streams. Thus, future aquatic CO2 emissions may depend on how biotic processes respond to the ongoing environmental change.},\n\tlanguage = {en},\n\tnumber = {S1},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Rocher-Ros, Gerard and Harms, Tamara K. and Sponseller, Ryan A. and Väisänen, Maria and Mörth, Carl-Magnus and Giesler, Reiner},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11564},\n\tkeywords = {\\#nosource},\n\tpages = {S169--S181},\n}\n\n\n\n\n\n Global warming is enhancing the mobilization of organic carbon (C) from Arctic soils into streams, where it can be mineralized to CO2 and released to the atmosphere. Abiotic photo-oxidation might drive C mineralization, but this process has not been quantitatively integrated with biological processes that also influence CO2 dynamics in aquatic ecosystems. We measured CO2 concentrations and the isotopic composition of dissolved inorganic C (δ13CDIC) at diel resolution in two Arctic streams, and coupled this with whole-system metabolism estimates to assess the effect of biotic and abiotic processes on stream C dynamics. CO2 concentrations consistently decreased from night to day, a pattern counter to the hypothesis that photo-oxidation is the dominant source of CO2. Instead, the observed decrease in CO2 during daytime was explained by photosynthetic rates, which were strongly correlated with diurnal changes in δ13CDIC values. However, on days when modeled photosynthetic rates were near zero, there was still a significant diel change in δ13CDIC values, suggesting that metabolic estimates are partly masked by O2 consumption from photo-oxidation. Our results suggest that 6–12 mmol CO2-C m−2 d−1 may be generated from photo-oxidation, a range that corresponds well to previous laboratory measurements. Moreover, ecosystem respiration rates were 10 times greater than published photo-oxidation rates for these Arctic streams, and accounted for 33–80% of total CO2 evasion. Our results suggest that metabolic activity is the dominant process for CO2 production in Arctic streams. Thus, future aquatic CO2 emissions may depend on how biotic processes respond to the ongoing environmental change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Nutrients influence seasonal metabolic patterns and total productivity of Arctic streams.\n \n \n \n \n\n\n \n Myrstener, M.; Gómez-Gener, L.; Rocher-Ros, G.; Giesler, R.; and Sponseller, R. A.\n\n\n \n\n\n\n Limnology and Oceanography, 66(S1): S182–S196. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11614\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{myrstener_nutrients_2021,\n\ttitle = {Nutrients influence seasonal metabolic patterns and total productivity of {Arctic} streams},\n\tvolume = {66},\n\tcopyright = {© 2020 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11614},\n\tdoi = {10.1002/lno.11614},\n\tabstract = {The seasonality of gross primary production (GPP) in streams is driven by multiple physical and chemical factors, yet incident light is often thought to be most important. In Arctic tundra streams, however, light is available in saturating amounts throughout the summer, but sharp declines in nutrient supply during the terrestrial growing season may constrain aquatic productivity. Given the opposing seasonality of these drivers, we hypothesized that “shoulder seasons”—spring and autumn—represent critical time windows when light and nutrients align to optimize rates of stream productivity in the Arctic. To test this, we measured annual patterns of GPP and biofilm accumulation in eight streams in Arctic Sweden. We found that the aquatic growing season length differed by 4 months across streams and was determined largely by the timing of ice-off in spring. During the growing season, temporal variability in GPP for nitrogen (N) poor streams was correlated with inorganic N concentration, while in more N-rich streams GPP was instead linked to changes in phosphorus and light. Annual GPP varied ninefold among streams and was enhanced by N availability, the length of ice-free period, and low flood frequency. Finally, network scale estimates of GPP highlight the overall significance of the shoulder seasons, which accounted for 48\\% of annual productivity. We suggest that the timing of ice off and nutrient supply from land interact to regulate the annual metabolic regimes of nutrient poor, Arctic streams, leading to unexpected peaks in productivity that are offset from the terrestrial growing season.},\n\tlanguage = {en},\n\tnumber = {S1},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Myrstener, Maria and Gómez-Gener, Lluís and Rocher-Ros, Gerard and Giesler, Reiner and Sponseller, Ryan A.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11614},\n\tkeywords = {\\#nosource},\n\tpages = {S182--S196},\n}\n\n\n\n\n\n The seasonality of gross primary production (GPP) in streams is driven by multiple physical and chemical factors, yet incident light is often thought to be most important. In Arctic tundra streams, however, light is available in saturating amounts throughout the summer, but sharp declines in nutrient supply during the terrestrial growing season may constrain aquatic productivity. Given the opposing seasonality of these drivers, we hypothesized that “shoulder seasons”—spring and autumn—represent critical time windows when light and nutrients align to optimize rates of stream productivity in the Arctic. To test this, we measured annual patterns of GPP and biofilm accumulation in eight streams in Arctic Sweden. We found that the aquatic growing season length differed by 4 months across streams and was determined largely by the timing of ice-off in spring. During the growing season, temporal variability in GPP for nitrogen (N) poor streams was correlated with inorganic N concentration, while in more N-rich streams GPP was instead linked to changes in phosphorus and light. Annual GPP varied ninefold among streams and was enhanced by N availability, the length of ice-free period, and low flood frequency. Finally, network scale estimates of GPP highlight the overall significance of the shoulder seasons, which accounted for 48% of annual productivity. We suggest that the timing of ice off and nutrient supply from land interact to regulate the annual metabolic regimes of nutrient poor, Arctic streams, leading to unexpected peaks in productivity that are offset from the terrestrial growing season.\n
\n\n\n\n \n\n \n \n \n \n \n \n Comparison of the distribution and phenology of Arctic Mountain plants between the early 20th and 21st centuries.\n \n \n \n \n\n\n \n MacDougall, A. S.; Caplat, P.; Olofsson, J.; Siewert, M. B.; Bonner, C.; Esch, E.; Lessard-Therrien, M.; Rosenzweig, H.; Schäfer, A.; Raker, P.; Ridha, H.; Bolmgren, K.; Fries, T. C. E.; and Larson, K.\n\n\n \n\n\n\n Global Change Biology, 27(20): 5070–5083. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15767\n\n\n\n
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\n\n\n@article{macdougall_comparison_2021,\n\ttitle = {Comparison of the distribution and phenology of {Arctic} {Mountain} plants between the early 20th and 21st centuries},\n\tvolume = {27},\n\tcopyright = {© 2021 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15767},\n\tdoi = {10.1111/gcb.15767},\n\tabstract = {Arctic plants are adapted to climatic variability, but their long-term responses to warming remain unclear. Responses may occur by range shifts, phenological adjustments in growth and reproduction, or both. Here, we compare distribution and phenology of 83 arctic and boreal mountain species, sampled identically in the early 20th (1917–1919) and 21st centuries (2017–2018) from a region of northern Sweden that has warmed significantly. We test two compensatory hypotheses to high-latitude warming—upward shifts in distribution, and earlier or extended growth and reproduction. For distribution, we show dramatic upward migration by 69\\% of species, averaging 6.1 m per decade, especially boreal woodland taxa whose upward expansion has reduced arctic montane habitat by 30\\%. Twenty percent of summit species showed distributional shifts but downward, especially moisture-associated snowbed flora. For phenology, we detected wide inter-annual variability in the onset of leafing and flowering in both eras. However, there was no detectable change in growing-season length, relating to two mechanisms. First, plot-level snow melt data starting in 1917 demonstrated that melt date, rather than vernal temperatures, better predicts plant emergence, with snow melt influenced by warmer years having greater snowfall—warmer springs did not always result in earlier emergence because snowbeds can persist longer. Second, the onset of reproductive senescence between eras was similar, even when plant emergence was earlier by a month, possibly due to intensified summer heat stress or hard-wired ‘canalization’ where senescence occurs regardless of summer temperature. Migrations in this system have possibly buffered arctic species against displacement by boreal expansion and warming, but ongoing temperature increases, woody plant invasion, and a potential lack of flexibility in timing of senescence may foreshadow challenges.},\n\tlanguage = {en},\n\tnumber = {20},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {MacDougall, Andrew S. and Caplat, Paul and Olofsson, Johan and Siewert, Matthias B. and Bonner, Colin and Esch, Ellen and Lessard-Therrien, Malie and Rosenzweig, Hannah and Schäfer, Anne-Kathrin and Raker, Pia and Ridha, Hassan and Bolmgren, Kjell and Fries, Thore C. E. and Larson, Keith},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15767},\n\tkeywords = {\\#nosource, arctic flora, climate change, historical data, migration, mountain, phenology, resiliency},\n\tpages = {5070--5083},\n}\n\n\n\n\n\n Arctic plants are adapted to climatic variability, but their long-term responses to warming remain unclear. Responses may occur by range shifts, phenological adjustments in growth and reproduction, or both. Here, we compare distribution and phenology of 83 arctic and boreal mountain species, sampled identically in the early 20th (1917–1919) and 21st centuries (2017–2018) from a region of northern Sweden that has warmed significantly. We test two compensatory hypotheses to high-latitude warming—upward shifts in distribution, and earlier or extended growth and reproduction. For distribution, we show dramatic upward migration by 69% of species, averaging 6.1 m per decade, especially boreal woodland taxa whose upward expansion has reduced arctic montane habitat by 30%. Twenty percent of summit species showed distributional shifts but downward, especially moisture-associated snowbed flora. For phenology, we detected wide inter-annual variability in the onset of leafing and flowering in both eras. However, there was no detectable change in growing-season length, relating to two mechanisms. First, plot-level snow melt data starting in 1917 demonstrated that melt date, rather than vernal temperatures, better predicts plant emergence, with snow melt influenced by warmer years having greater snowfall—warmer springs did not always result in earlier emergence because snowbeds can persist longer. Second, the onset of reproductive senescence between eras was similar, even when plant emergence was earlier by a month, possibly due to intensified summer heat stress or hard-wired ‘canalization’ where senescence occurs regardless of summer temperature. Migrations in this system have possibly buffered arctic species against displacement by boreal expansion and warming, but ongoing temperature increases, woody plant invasion, and a potential lack of flexibility in timing of senescence may foreshadow challenges.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lowered nutritional quality of plankton caused by global environmental changes.\n \n \n \n \n\n\n \n Lau, D. C. P.; Jonsson, A.; Isles, P. D. F.; Creed, I. F.; and Bergström, A.\n\n\n \n\n\n\n Global Change Biology, 27(23): 6294–6306. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15887\n\n\n\n
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\n\n\n@article{lau_lowered_2021,\n\ttitle = {Lowered nutritional quality of plankton caused by global environmental changes},\n\tvolume = {27},\n\tcopyright = {© 2021 The Authors. Global Change Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15887},\n\tdoi = {10.1111/gcb.15887},\n\tabstract = {Global environmental changes are causing widespread nutrient depletion, declines in the ratio of dissolved inorganic nitrogen (N) to total phosphorus (DIN:TP), and increases in both water temperature and terrestrial colored dissolved organic carbon (DOC) concentration (browning) in high-latitude northern lakes. Declining lake DIN:TP, warming, and browning alter the nutrient limitation regime and biomass of phytoplankton, but how these stressors together affect the nutritional quality in terms of polyunsaturated fatty acid (PUFA) contents of the pelagic food web components remains unknown. We assessed the fatty acid compositions of seston and zooplankton in 33 lakes across south-to-north and boreal-to-subarctic gradients in Sweden. Data showed higher lake DIN:TP in the south than in the north, and that boreal lakes were warmer and browner than subarctic lakes. Lake DIN:TP strongly affected the PUFA contents—especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—in seston, calanoids, and copepods (as a group), but not in cladocerans. The EPA+DHA contents increased by 123\\% in seston, 197\\% in calanoids, and 230\\% in copepods across a lake molar DIN:TP gradient from 0.17 to 14.53, indicating lower seston and copepod nutritional quality in the more N-limited lakes (those with lower DIN:TP). Water temperature affected EPA+DHA contents of zooplankton, especially cladocerans, but not seston. Cladoceran EPA+DHA contents were reduced by ca. 6\\% for every 1°C increase in surface water. Also, the EPA, DHA, or EPA+DHA contents of Bosmina, cyclopoids, and copepods increased in lakes with higher DOC concentrations or aromaticity. Our findings indicate that zooplankton food quality for higher consumers will decrease with warming alone (for cladocerans) or in combination with declining lake DIN:TP (for copepods), but impacts of these stressors are moderated by lake browning. Global environmental changes that drive northern lakes toward more N-limited, warmer, and browner conditions will reduce PUFA availability and nutritional quality of the pelagic food web components.},\n\tlanguage = {en},\n\tnumber = {23},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Lau, Danny C. P. and Jonsson, Anders and Isles, Peter D. F. and Creed, Irena F. and Bergström, Ann‑Kristin},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15887},\n\tkeywords = {\\#nosource, N:P stoichiometry, boreal lakes, dissolved organic carbon, fatty acids, nitrogen deposition, phytoplankton, seston, subarctic lakes, warming, zooplankton},\n\tpages = {6294--6306},\n}\n\n\n\n\n\n Global environmental changes are causing widespread nutrient depletion, declines in the ratio of dissolved inorganic nitrogen (N) to total phosphorus (DIN:TP), and increases in both water temperature and terrestrial colored dissolved organic carbon (DOC) concentration (browning) in high-latitude northern lakes. Declining lake DIN:TP, warming, and browning alter the nutrient limitation regime and biomass of phytoplankton, but how these stressors together affect the nutritional quality in terms of polyunsaturated fatty acid (PUFA) contents of the pelagic food web components remains unknown. We assessed the fatty acid compositions of seston and zooplankton in 33 lakes across south-to-north and boreal-to-subarctic gradients in Sweden. Data showed higher lake DIN:TP in the south than in the north, and that boreal lakes were warmer and browner than subarctic lakes. Lake DIN:TP strongly affected the PUFA contents—especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—in seston, calanoids, and copepods (as a group), but not in cladocerans. The EPA+DHA contents increased by 123% in seston, 197% in calanoids, and 230% in copepods across a lake molar DIN:TP gradient from 0.17 to 14.53, indicating lower seston and copepod nutritional quality in the more N-limited lakes (those with lower DIN:TP). Water temperature affected EPA+DHA contents of zooplankton, especially cladocerans, but not seston. Cladoceran EPA+DHA contents were reduced by ca. 6% for every 1°C increase in surface water. Also, the EPA, DHA, or EPA+DHA contents of Bosmina, cyclopoids, and copepods increased in lakes with higher DOC concentrations or aromaticity. Our findings indicate that zooplankton food quality for higher consumers will decrease with warming alone (for cladocerans) or in combination with declining lake DIN:TP (for copepods), but impacts of these stressors are moderated by lake browning. Global environmental changes that drive northern lakes toward more N-limited, warmer, and browner conditions will reduce PUFA availability and nutritional quality of the pelagic food web components.\n
\n\n\n\n \n\n \n \n \n \n \n \n Trade-offs Between Light and Nutrient Availability Across Gradients of Dissolved Organic Carbon Lead to Spatially and Temporally Variable Responses of Lake Phytoplankton Biomass to Browning.\n \n \n \n \n\n\n \n Isles, P. D. F.; Creed, I. F.; Jonsson, A.; and Bergström, A.\n\n\n \n\n\n\n Ecosystems, 24(8): 1837–1852. December 2021.\n \n\n\n\n
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\n\n\n@article{isles_trade-offs_2021,\n\ttitle = {Trade-offs {Between} {Light} and {Nutrient} {Availability} {Across} {Gradients} of {Dissolved} {Organic} {Carbon} {Lead} to {Spatially} and {Temporally} {Variable} {Responses} of {Lake} {Phytoplankton} {Biomass} to {Browning}},\n\tvolume = {24},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-021-00619-7},\n\tdoi = {10.1007/s10021-021-00619-7},\n\tabstract = {Northern lakes are experiencing widespread increases in dissolved organic carbon (DOC) that are likely to lead to changes in pelagic phytoplankton biomass. Pelagic phytoplankton biomass responds to trade-offs between light and nutrient availability. However, the influence of DOC light absorbing properties and carbon–nutrient stoichiometry on phytoplankton biomass across seasonal or spatial gradients has not been assessed. Here, we analyzed data from almost 5000 lakes to examine how the carbon–phytoplankton biomass relationship is influenced by seasonal changes in light availability, DOC light absorbing properties (carbon-specific visual absorbance, SVA420), and DOC–nutrient [total nitrogen (TN) and total phosphorus (TP)] stoichiometry, using TOC as a proxy for DOC. We found evidence for trade-offs between light and nutrient availability in the relationship between DOC and phytoplankton biomass [chlorophyll (chl)-a], with the shape of the relationship varying with season. A clear unimodal relationship was found only in the fall, particularly in the subsets of lakes with the highest TOC:TP. Observed trends of increasing TOC:TP and decreasing TOC:TN suggest that the effects of future browning will be contingent on future changes in carbon–nutrient stoichiometry. If browning continues, phytoplankton biomass will likely increase in most northern lakes, with increases of up to 76\\% for a 1.7 mg L−1 increase in DOC expected in subarctic regions, where DOC, SVA420, DOC:TN, and DOC:TP are all low. In boreal regions with higher DOC and higher SVA420, and thus lower light availability, lakes may experience only moderate increases or even decreases in phytoplankton biomass with future browning.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2024-03-26},\n\tjournal = {Ecosystems},\n\tauthor = {Isles, Peter D. F. and Creed, Irena F. and Jonsson, Anders and Bergström, Ann-Kristin},\n\tmonth = dec,\n\tyear = {2021},\n\tkeywords = {\\#nosource, Boreal, Browning, Chlorophyll-a, DOC, DOC:TN, DOC:TP, Lake, Stoichiometry, Subarctic, Sweden},\n\tpages = {1837--1852},\n}\n\n\n\n\n\n Northern lakes are experiencing widespread increases in dissolved organic carbon (DOC) that are likely to lead to changes in pelagic phytoplankton biomass. Pelagic phytoplankton biomass responds to trade-offs between light and nutrient availability. However, the influence of DOC light absorbing properties and carbon–nutrient stoichiometry on phytoplankton biomass across seasonal or spatial gradients has not been assessed. Here, we analyzed data from almost 5000 lakes to examine how the carbon–phytoplankton biomass relationship is influenced by seasonal changes in light availability, DOC light absorbing properties (carbon-specific visual absorbance, SVA420), and DOC–nutrient [total nitrogen (TN) and total phosphorus (TP)] stoichiometry, using TOC as a proxy for DOC. We found evidence for trade-offs between light and nutrient availability in the relationship between DOC and phytoplankton biomass [chlorophyll (chl)-a], with the shape of the relationship varying with season. A clear unimodal relationship was found only in the fall, particularly in the subsets of lakes with the highest TOC:TP. Observed trends of increasing TOC:TP and decreasing TOC:TN suggest that the effects of future browning will be contingent on future changes in carbon–nutrient stoichiometry. If browning continues, phytoplankton biomass will likely increase in most northern lakes, with increases of up to 76% for a 1.7 mg L−1 increase in DOC expected in subarctic regions, where DOC, SVA420, DOC:TN, and DOC:TP are all low. In boreal regions with higher DOC and higher SVA420, and thus lower light availability, lakes may experience only moderate increases or even decreases in phytoplankton biomass with future browning.\n
\n\n\n\n \n\n \n \n \n \n \n \n An experimental test of climate change effects in northern lakes: Increasing allochthonous organic matter and warming alters autumn primary production.\n \n \n \n \n\n\n \n Hamdan, M.; Byström, P.; Hotchkiss, E. R.; Al-Haidarey, M. J.; and Karlsson, J.\n\n\n \n\n\n\n Freshwater Biology, 66(5): 815–825. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13679\n\n\n\n
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\n\n\n@article{hamdan_experimental_2021,\n\ttitle = {An experimental test of climate change effects in northern lakes: {Increasing} allochthonous organic matter and warming alters autumn primary production},\n\tvolume = {66},\n\tcopyright = {© 2021 The Authors. Freshwater Biology published by John Wiley \\& Sons Ltd.},\n\tissn = {1365-2427},\n\tshorttitle = {An experimental test of climate change effects in northern lakes},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.13679},\n\tdoi = {10.1111/fwb.13679},\n\tabstract = {Climate changes are predicted to influence gross primary production (GPP) of lakes directly through warming and indirectly through increased loads of allochthonous coloured dissolved organic matter (cDOM) from surrounding landscapes. However, few studies have investigated this combined effect. Here we tested the effects of warming (elevated 3℃) and cDOM input (three levels of humic river water addition) on GPP in autumn (2 months including open water and ice-covered periods) in experimental pond ecosystems. The cDOM input decreased whole-ecosystem GPP at natural temperature conditions mainly as a result of lower benthic GPP not fully counteracted by an increase in pelagic GPP, while warming increased whole-ecosystem GPP due to a positive response of mainly pelagic GPP at all levels of cDOM input. Warming delayed autumn ice cover formation by 2 weeks but did not affect light availability in the water column compared to ambient ice-covered treatments. Gross primary production during this period was still affected by warming and cDOM. The results stress the importance of accounting for multiple climate drivers and habitats when predicting lake GPP responses to climate change. We conclude that climate change may shift whole-ecosystem GPP through different responses of habitat-specific GPP to increasing cDOM inputs and warming.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-26},\n\tjournal = {Freshwater Biology},\n\tauthor = {Hamdan, Mohammed and Byström, Pär and Hotchkiss, Erin R. and Al-Haidarey, Mohammed J. and Karlsson, Jan},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.13679},\n\tkeywords = {\\#nosource, brownification, habitat-specific, limitation, rising temperature, whole productivity},\n\tpages = {815--825},\n}\n\n\n\n\n\n Climate changes are predicted to influence gross primary production (GPP) of lakes directly through warming and indirectly through increased loads of allochthonous coloured dissolved organic matter (cDOM) from surrounding landscapes. However, few studies have investigated this combined effect. Here we tested the effects of warming (elevated 3℃) and cDOM input (three levels of humic river water addition) on GPP in autumn (2 months including open water and ice-covered periods) in experimental pond ecosystems. The cDOM input decreased whole-ecosystem GPP at natural temperature conditions mainly as a result of lower benthic GPP not fully counteracted by an increase in pelagic GPP, while warming increased whole-ecosystem GPP due to a positive response of mainly pelagic GPP at all levels of cDOM input. Warming delayed autumn ice cover formation by 2 weeks but did not affect light availability in the water column compared to ambient ice-covered treatments. Gross primary production during this period was still affected by warming and cDOM. The results stress the importance of accounting for multiple climate drivers and habitats when predicting lake GPP responses to climate change. We conclude that climate change may shift whole-ecosystem GPP through different responses of habitat-specific GPP to increasing cDOM inputs and warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Pulse grazing by reindeer (Rangifer tarandus) can increase the phylogenetic diversity of vascular plant communities in the Fennoscandian tundra.\n \n \n \n \n\n\n \n Gibson, K.; Olofsson, J.; Mooers, A. Ø.; and Monroe, M. J.\n\n\n \n\n\n\n Ecology and Evolution, 11(21): 14598–14614. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.8131\n\n\n\n
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\n\n\n@article{gibson_pulse_2021,\n\ttitle = {Pulse grazing by reindeer ({Rangifer} tarandus) can increase the phylogenetic diversity of vascular plant communities in the {Fennoscandian} tundra},\n\tvolume = {11},\n\tcopyright = {© 2021 The Authors. Ecology and Evolution published by John Wiley \\& Sons Ltd.},\n\tissn = {2045-7758},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.8131},\n\tdoi = {10.1002/ece3.8131},\n\tabstract = {Herbivore grazing is an important determinant of plant community assemblages. Thus, it is essential to understand its impact to direct conservation efforts in regions where herbivores are managed. While the impacts of reindeer (Rangifer tarandus) grazing on plant biodiversity and community composition in the Fennoscandian tundra are well studied, the impact of reindeer grazing on phylogenetic community structure is not. We used data from a multiyear quasi-experimental study in northern Fennoscandia to analyze the effect of reindeer grazing on plant community diversity including its phylogenetic structure. Our study design used a permanent fence constructed in the 1960s and temporary fences constructed along the permanent fence to expose plant communities to three different grazing regimes: light (almost never grazed), pulse (grazed every other year), and press (chronic grazing for over 40 years). Similar to previous studies on low productivity ecosystems in this region, the species richness and evenness of plant communities with pulse and press grazing did not differ from communities with light grazing. Also consistent with previous studies in this region, we observed a transition from shrub-dominated communities with light grazing to graminoid-dominated communities with pulse and press grazing. Interestingly, communities with pulse, but not press, grazing were more phylogenetically dispersed than communities with light grazing. If grazing pulses can increase the phylogenetic diversity of plant communities, our result suggests changes in reindeer management allowing for pulses of grazing to increase phylogenetic diversity of plant communities.},\n\tlanguage = {en},\n\tnumber = {21},\n\turldate = {2024-03-26},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Gibson, Kate and Olofsson, Johan and Mooers, Arne Ø. and Monroe, Melanie J.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.8131},\n\tkeywords = {\\#nosource, biodiversity, community structure, grazing, herbivore, phylogenetic diversity},\n\tpages = {14598--14614},\n}\n\n\n\n\n\n Herbivore grazing is an important determinant of plant community assemblages. Thus, it is essential to understand its impact to direct conservation efforts in regions where herbivores are managed. While the impacts of reindeer (Rangifer tarandus) grazing on plant biodiversity and community composition in the Fennoscandian tundra are well studied, the impact of reindeer grazing on phylogenetic community structure is not. We used data from a multiyear quasi-experimental study in northern Fennoscandia to analyze the effect of reindeer grazing on plant community diversity including its phylogenetic structure. Our study design used a permanent fence constructed in the 1960s and temporary fences constructed along the permanent fence to expose plant communities to three different grazing regimes: light (almost never grazed), pulse (grazed every other year), and press (chronic grazing for over 40 years). Similar to previous studies on low productivity ecosystems in this region, the species richness and evenness of plant communities with pulse and press grazing did not differ from communities with light grazing. Also consistent with previous studies in this region, we observed a transition from shrub-dominated communities with light grazing to graminoid-dominated communities with pulse and press grazing. Interestingly, communities with pulse, but not press, grazing were more phylogenetically dispersed than communities with light grazing. If grazing pulses can increase the phylogenetic diversity of plant communities, our result suggests changes in reindeer management allowing for pulses of grazing to increase phylogenetic diversity of plant communities.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes.\n \n \n \n \n\n\n \n Bergström, A.; Deininger, A.; Jonsson, A.; Karlsson, J.; and Vrede, T.\n\n\n \n\n\n\n Hydrobiologia, 848(21): 4991–5010. December 2021.\n \n\n\n\n
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\n\n\n@article{bergstrom_effects_2021,\n\ttitle = {Effects of nitrogen enrichment on zooplankton biomass and {N}:{P} recycling ratios across a {DOC} gradient in northern-latitude lakes},\n\tvolume = {848},\n\tissn = {1573-5117},\n\tshorttitle = {Effects of nitrogen enrichment on zooplankton biomass and {N}},\n\turl = {https://doi.org/10.1007/s10750-021-04689-5},\n\tdoi = {10.1007/s10750-021-04689-5},\n\tabstract = {We used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.},\n\tlanguage = {en},\n\tnumber = {21},\n\turldate = {2024-03-26},\n\tjournal = {Hydrobiologia},\n\tauthor = {Bergström, A.-K. and Deininger, A. and Jonsson, A. and Karlsson, J. and Vrede, T.},\n\tmonth = dec,\n\tyear = {2021},\n\tkeywords = {\\#nosource, Dissolved organic carbon, Food quantity-quality, Light, Nitrogen, Pelagic food web, Phosphorus},\n\tpages = {4991--5010},\n}\n\n\n\n\n\n We used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of temperature and terrestrial carbon on primary production in lake ecosystems.\n \n \n \n \n\n\n \n Hamdan, M.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2021.\n Publisher: Umeå University\n\n\n\n
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\n\n\n@phdthesis{hamdan_effects_2021,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Effects of temperature and terrestrial carbon on primary production in lake ecosystems},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-182526},\n\tabstract = {Climate warming is predicted to affect northern lake food webs in two ways: (1)directly via changes in water temperature and ice conditions, and (2) indirectlyvia changes in catchment characteristi ...},\n\tlanguage = {eng},\n\turldate = {2023-07-25},\n\tschool = {Umeå University},\n\tauthor = {Hamdan, Mohammed},\n\tcollaborator = {Karlsson, Jan and Byström, Pär and Hotchkiss, Erin R.},\n\tyear = {2021},\n\tnote = {Publisher: Umeå University},\n\tkeywords = {⛔ No DOI found},\n}\n\n\n\n\n\n Climate warming is predicted to affect northern lake food webs in two ways: (1)directly via changes in water temperature and ice conditions, and (2) indirectlyvia changes in catchment characteristi ...\n
\n\n\n\n \n\n \n \n \n \n \n A Review of Abisko Case Study: Recent and Past Trees an Climates at the Arctic/Alpine Margin in Swedish Lapland.\n \n \n \n\n\n \n Kullman, L.\n\n\n \n\n\n\n In Turkman, M., editor(s), Challenging Issues on Environment and Earth Science, volume 2, pages 1–25. Book Publisher International, March 2021.\n \n\n\n\n
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\n\n\n@incollection{kullman_review_2021,\n\ttitle = {A {Review} of {Abisko} {Case} {Study}: {Recent} and {Past} {Trees} an {Climates} at the {Arctic}/{Alpine} {Margin} in {Swedish} {Lapland}},\n\tvolume = {2},\n\tisbn = {978-93-90768-63-9},\n\tabstract = {For about a century, Abisko Scientific Research Station in northern Swedish Lapland has served as a logistic base for high-quality geoecological research in subalpine/subarctic environments. In recent years, and driven by the prospect of alleged man-made global warming, much of the scientific focus has been on dynamics of the treeline ecotone. In this context, field observations, analyses and interpretations emanating from research carried out in the Abisko region are discussed in perspective of recent observations and analyses. Local mountain birch (Betula pubescens ssp. czerepanovii) treeline rise by maximum 230 m during the past 100 years conforms quantitatively to data obtained further south in the Scandes. This broad-scale inter-regional coincidence indicates that a common operative agent has been responsible. The most likely candidate is recorded secular climate warming by 2.5°C. This contention is further supported by age structure analysis in the birch treeline advance zone, indicating that the vegetative initiation of new trees peaked during the warm 1930s, when reindeer number were high and reached a nadir during the relatively cold 1960s and 1970s, coincident with smaller reindeer herds. These data suggest, contrary to previous hypotheses, stating that, relative to climate change, intensity of reindeer browsing has been of minor importance for birch treeline dynamics. The upper limit of closed stands of mountain birch and pine have shifted relatively insignificantly in elevational position during the predominantly warm past 100 years. Over the same period or longer, common aspen (Populus tremula) has frequently occurred as low-growing krummholz (stunted growth forms) over the entire mountain birch region. During the warm 1930s and just like birch, rapid height increment was initiated and has continued up to the present day. Thereby, many individuals have attained tree-sized in recent decades. Accordingly, aspen (Populus tremula) has, presumably in response to climate warming, become a more conspicuous element in the mountain birch forest. The current analyses refute prior claims that aspen regeneration is accomplished by seed regeneration rather than phenotypic adjustment of old-growth creeping individuals. Picea abies and Larix sp. are recorded as new species in the Abisko area. In accordance with prior analyses in other parts of the Scandes, megafossil data show that the treelines of Scots pine (Pinus sylvestris), mountain birch (Betula pubescens ssp. czerepanovii) and grey alder (Alnus incana) peaked in the early Holocene. Based on the elevational difference between early Holocene and present treeline positions (adjusted for 100 m land uplift) it may be inferred that the summer temperatures exceeded those of the last few decades by about 3.0°C. This study challenges recent proposals that aspen is currently spreading upslope and westwards in the birch forest belt by seed establishment of new individuals. In response to recent warming they have attained tree size and have become a more conspicuous element of the landscape.},\n\tbooktitle = {Challenging {Issues} on {Environment} and {Earth} {Science}},\n\tpublisher = {Book Publisher International},\n\tauthor = {Kullman, Leif},\n\teditor = {Turkman, Mustafa},\n\tmonth = mar,\n\tyear = {2021},\n\tdoi = {10.9734/bpi/ciees/v2/7576D},\n\tpages = {1--25},\n}\n\n\n\n\n\n For about a century, Abisko Scientific Research Station in northern Swedish Lapland has served as a logistic base for high-quality geoecological research in subalpine/subarctic environments. In recent years, and driven by the prospect of alleged man-made global warming, much of the scientific focus has been on dynamics of the treeline ecotone. In this context, field observations, analyses and interpretations emanating from research carried out in the Abisko region are discussed in perspective of recent observations and analyses. Local mountain birch (Betula pubescens ssp. czerepanovii) treeline rise by maximum 230 m during the past 100 years conforms quantitatively to data obtained further south in the Scandes. This broad-scale inter-regional coincidence indicates that a common operative agent has been responsible. The most likely candidate is recorded secular climate warming by 2.5°C. This contention is further supported by age structure analysis in the birch treeline advance zone, indicating that the vegetative initiation of new trees peaked during the warm 1930s, when reindeer number were high and reached a nadir during the relatively cold 1960s and 1970s, coincident with smaller reindeer herds. These data suggest, contrary to previous hypotheses, stating that, relative to climate change, intensity of reindeer browsing has been of minor importance for birch treeline dynamics. The upper limit of closed stands of mountain birch and pine have shifted relatively insignificantly in elevational position during the predominantly warm past 100 years. Over the same period or longer, common aspen (Populus tremula) has frequently occurred as low-growing krummholz (stunted growth forms) over the entire mountain birch region. During the warm 1930s and just like birch, rapid height increment was initiated and has continued up to the present day. Thereby, many individuals have attained tree-sized in recent decades. Accordingly, aspen (Populus tremula) has, presumably in response to climate warming, become a more conspicuous element in the mountain birch forest. The current analyses refute prior claims that aspen regeneration is accomplished by seed regeneration rather than phenotypic adjustment of old-growth creeping individuals. Picea abies and Larix sp. are recorded as new species in the Abisko area. In accordance with prior analyses in other parts of the Scandes, megafossil data show that the treelines of Scots pine (Pinus sylvestris), mountain birch (Betula pubescens ssp. czerepanovii) and grey alder (Alnus incana) peaked in the early Holocene. Based on the elevational difference between early Holocene and present treeline positions (adjusted for 100 m land uplift) it may be inferred that the summer temperatures exceeded those of the last few decades by about 3.0°C. This study challenges recent proposals that aspen is currently spreading upslope and westwards in the birch forest belt by seed establishment of new individuals. In response to recent warming they have attained tree size and have become a more conspicuous element of the landscape.\n
\n\n\n\n \n\n \n \n \n \n \n Predicting Soil Respiration from Plant Productivity (NDVI) in a Sub-Arctic Tundra Ecosystem.\n \n \n \n\n\n \n Azevedo, O.; Parker, T.; Siewert, M.; and Subke, J.\n\n\n \n\n\n\n Remote Sensing, 13: 2571. June 2021.\n \n\n\n\n
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\n\n\n\n@article{azevedo_predicting_2021,\n\ttitle = {Predicting {Soil} {Respiration} from {Plant} {Productivity} ({NDVI}) in a {Sub}-{Arctic} {Tundra} {Ecosystem}},\n\tvolume = {13},\n\tdoi = {10.3390/rs13132571},\n\tjournal = {Remote Sensing},\n\tauthor = {Azevedo, Olivia and Parker, Thomas and Siewert, Matthias and Subke, Jens-Arne},\n\tmonth = jun,\n\tyear = {2021},\n\tpages = {2571},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Can moisture affect temperature dependences of microbial growth and respiration?.\n \n \n \n \n\n\n \n Cruz-Paredes, C.; Tájmel, D.; and Rousk, J.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 156: 108223. May 2021.\n \n\n\n\n
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\n\n\n@article{cruz-paredes_can_2021,\n\ttitle = {Can moisture affect temperature dependences of microbial growth and respiration?},\n\tvolume = {156},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S003807172100095X},\n\tdoi = {10.1016/j.soilbio.2021.108223},\n\tabstract = {It is of great importance to understand how terrestrial ecosystems will respond to global changes. However, most experimental approaches have focused on single factors. In natural systems, moisture and temperature often change simultaneously, and they can interact and shape microbial responses. Even though soil moisture and temperature are very important factors controlling microbial activity, there is disagreement on the dependence of microbial rates on temperature and moisture as well as their sensitivity when both variables change simultaneously. Here we created a moisture gradient and determined high resolution intrinsic temperature dependences for bacterial and fungal growth rates as well as respiration rates. We found that microbial rates decreased with lower moisture and increased with higher temperatures until optimum values. Additionally, we found independence between temperature and moisture as rate modifiers. We also found that temperature sensitivities (Q10) for microbial growth and respiration were not affected by changes in moisture. This provided an experimental framework to validate assumptions of temperature and moisture rate modifiers used in ecosystem and global cycling models (GCMs).},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Cruz-Paredes, Carla and Tájmel, Dániel and Rousk, Johannes},\n\tmonth = may,\n\tyear = {2021},\n\tkeywords = {Microbial growth, Moisture, Soil respiration, Temperature dependence},\n\tpages = {108223},\n}\n\n\n\n\n\n It is of great importance to understand how terrestrial ecosystems will respond to global changes. However, most experimental approaches have focused on single factors. In natural systems, moisture and temperature often change simultaneously, and they can interact and shape microbial responses. Even though soil moisture and temperature are very important factors controlling microbial activity, there is disagreement on the dependence of microbial rates on temperature and moisture as well as their sensitivity when both variables change simultaneously. Here we created a moisture gradient and determined high resolution intrinsic temperature dependences for bacterial and fungal growth rates as well as respiration rates. We found that microbial rates decreased with lower moisture and increased with higher temperatures until optimum values. Additionally, we found independence between temperature and moisture as rate modifiers. We also found that temperature sensitivities (Q10) for microbial growth and respiration were not affected by changes in moisture. This provided an experimental framework to validate assumptions of temperature and moisture rate modifiers used in ecosystem and global cycling models (GCMs).\n
\n\n\n\n \n\n \n \n \n \n \n \n Phenological stage of tundra vegetation controls bidirectional exchange of BVOCs in a climate change experiment on a subarctic heath.\n \n \n \n \n\n\n \n Baggesen, N.; Li, T.; Seco, R.; Holst, T.; Michelsen, A.; and Rinnan, R.\n\n\n \n\n\n\n Global Change Biology, 27(12): 2928–2944. June 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{baggesen_phenological_2021,\n\ttitle = {Phenological stage of tundra vegetation controls bidirectional exchange of {BVOCs} in a climate change experiment on a subarctic heath},\n\tvolume = {27},\n\tissn = {1354-1013},\n\turl = {https://doi.org/10.1111/gcb.15596},\n\tdoi = {10.1111/gcb.15596},\n\tabstract = {Abstract Traditionally, biogenic volatile organic compound (BVOC) emissions are often considered a unidirectional flux, from the ecosystem to the atmosphere, but recent studies clearly show the potential for bidirectional exchange. Here we aimed to investigate how warming and leaf litter addition affect the bidirectional exchange (flux) of BVOCs in a long-term field experiment in the Subarctic. We also assessed changes in net BVOC fluxes in relation to the time of day and the influence of different plant phenological stages. The study was conducted in a full factorial experiment with open top chamber warming and annual litter addition treatments in a tundra heath in Abisko, Northern Sweden. After 18 years of treatments, ecosystem-level net BVOC fluxes were measured in the experimental plots using proton-transfer-reaction time-of-flight mass spectrometry (PTR?ToF?MS). The warming treatment increased monoterpene and isoprene emissions by ≈50\\%. Increasing temperature, due to diurnal variations, can both increase BVOC emission and simultaneously, increase ecosystem uptake. For any given treatment, monoterpene, isoprene, and acetone emissions also increased with increasing ambient air temperatures caused by diurnal variability. Acetaldehyde, methanol, and sesquiterpenes decreased likely due to a deposition flux. For litter addition, only a significant indirect effect on isoprene and monoterpene fluxes (decrease by {\\textasciitilde}50\\%?75\\%) was observed. Litter addition may change soil moisture conditions, leading to changes in plant species composition and biomass, which could subsequently result in changes to BVOC emission compositions. Phenological stages significantly affected fluxes of methanol, isoprene and monoterpenes. We suggest that plant phenological stages differ in impacts on BVOC net emissions, but ambient air temperature and photosynthetically active radiation (PAR) also interact and influence BVOC net emissions differently. Our results may also suggest that BVOC fluxes are not only a response to changes in temperature and light intensity, as the circadian clock also affects emission rates.},\n\tnumber = {12},\n\turldate = {2023-07-22},\n\tjournal = {Global Change Biology},\n\tauthor = {Baggesen, Nanna and Li, Tao and Seco, Roger and Holst, Thomas and Michelsen, Anders and Rinnan, Riikka},\n\tmonth = jun,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Arctic, BVOC, climate change, methanol, phenology, plant volatiles, terpenoids, tundra},\n\tpages = {2928--2944},\n}\n\n\n\n\n\n Abstract Traditionally, biogenic volatile organic compound (BVOC) emissions are often considered a unidirectional flux, from the ecosystem to the atmosphere, but recent studies clearly show the potential for bidirectional exchange. Here we aimed to investigate how warming and leaf litter addition affect the bidirectional exchange (flux) of BVOCs in a long-term field experiment in the Subarctic. We also assessed changes in net BVOC fluxes in relation to the time of day and the influence of different plant phenological stages. The study was conducted in a full factorial experiment with open top chamber warming and annual litter addition treatments in a tundra heath in Abisko, Northern Sweden. After 18 years of treatments, ecosystem-level net BVOC fluxes were measured in the experimental plots using proton-transfer-reaction time-of-flight mass spectrometry (PTR?ToF?MS). The warming treatment increased monoterpene and isoprene emissions by ≈50%. Increasing temperature, due to diurnal variations, can both increase BVOC emission and simultaneously, increase ecosystem uptake. For any given treatment, monoterpene, isoprene, and acetone emissions also increased with increasing ambient air temperatures caused by diurnal variability. Acetaldehyde, methanol, and sesquiterpenes decreased likely due to a deposition flux. For litter addition, only a significant indirect effect on isoprene and monoterpene fluxes (decrease by ~50%?75%) was observed. Litter addition may change soil moisture conditions, leading to changes in plant species composition and biomass, which could subsequently result in changes to BVOC emission compositions. Phenological stages significantly affected fluxes of methanol, isoprene and monoterpenes. We suggest that plant phenological stages differ in impacts on BVOC net emissions, but ambient air temperature and photosynthetically active radiation (PAR) also interact and influence BVOC net emissions differently. Our results may also suggest that BVOC fluxes are not only a response to changes in temperature and light intensity, as the circadian clock also affects emission rates.\n
\n\n\n\n \n\n \n \n \n \n \n \n A tipping point in carbon storage when forest expands into tundra is related to mycorrhizal recycling of nitrogen.\n \n \n \n \n\n\n \n Clemmensen, K. E.; Durling, M. B.; Michelsen, A.; Hallin, S.; Finlay, R. D.; and Lindahl, B. D.\n\n\n \n\n\n\n Ecology Letters, 24(6): 1193–1204. June 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{clemmensen_tipping_2021,\n\ttitle = {A tipping point in carbon storage when forest expands into tundra is related to mycorrhizal recycling of nitrogen},\n\tvolume = {24},\n\tissn = {1461-023X},\n\turl = {https://doi.org/10.1111/ele.13735},\n\tdoi = {10.1111/ele.13735},\n\tabstract = {Abstract Tundra ecosystems are global belowground sinks for atmospheric CO2. Ongoing warming-induced encroachment by shrubs and trees risks turning this sink into a CO2 source, resulting in a positive feedback on climate warming. To advance mechanistic understanding of how shifts in mycorrhizal types affect long-term carbon (C) and nitrogen (N) stocks, we studied small-scale soil depth profiles of fungal communities and C?N dynamics across a subarctic-alpine forest-heath vegetation gradient. Belowground organic stocks decreased abruptly at the transition from heath to forest, linked to the presence of certain tree-associated ectomycorrhizal fungi that contribute to decomposition when mining N from organic matter. In contrast, ericoid mycorrhizal plants and fungi were associated with organic matter accumulation and slow decomposition. If climatic controls on arctic-alpine forest lines are relaxed, increased decomposition will likely outbalance increased plant productivity, decreasing the overall C sink capacity of displaced tundra.},\n\tnumber = {6},\n\turldate = {2023-07-22},\n\tjournal = {Ecology Letters},\n\tauthor = {Clemmensen, Karina Engelbrecht and Durling, Mikael Brandström and Michelsen, Anders and Hallin, Sara and Finlay, Roger D. and Lindahl, Björn D.},\n\tmonth = jun,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Arctic warming, carbon sequestration, decomposition, functional genes, meta-barcoding, mycorrhizal type, nitrogen cycling, soil fungal communities, stable isotopes, treeline ecotone},\n\tpages = {1193--1204},\n}\n\n\n\n\n\n Abstract Tundra ecosystems are global belowground sinks for atmospheric CO2. Ongoing warming-induced encroachment by shrubs and trees risks turning this sink into a CO2 source, resulting in a positive feedback on climate warming. To advance mechanistic understanding of how shifts in mycorrhizal types affect long-term carbon (C) and nitrogen (N) stocks, we studied small-scale soil depth profiles of fungal communities and C?N dynamics across a subarctic-alpine forest-heath vegetation gradient. Belowground organic stocks decreased abruptly at the transition from heath to forest, linked to the presence of certain tree-associated ectomycorrhizal fungi that contribute to decomposition when mining N from organic matter. In contrast, ericoid mycorrhizal plants and fungi were associated with organic matter accumulation and slow decomposition. If climatic controls on arctic-alpine forest lines are relaxed, increased decomposition will likely outbalance increased plant productivity, decreasing the overall C sink capacity of displaced tundra.\n
\n\n\n\n \n\n \n \n \n \n \n \n Root trait–microbial relationships across tundra plant species.\n \n \n \n \n\n\n \n Spitzer, C. M.; Lindahl, B.; Wardle, D. A.; Sundqvist, M. K.; Gundale, M. J.; Fanin, N.; and Kardol, P.\n\n\n \n\n\n\n New Phytologist, 229(3): 1508–1520. February 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{spitzer_root_2021,\n\ttitle = {Root trait–microbial relationships across tundra plant species},\n\tvolume = {229},\n\tissn = {0028-646X},\n\turl = {https://doi.org/10.1111/nph.16982},\n\tdoi = {10.1111/nph.16982},\n\tabstract = {Summary Fine roots, and their functional traits, influence associated rhizosphere microorganisms via root exudation and root litter quality. However, little information is known about their relationship with rhizosphere microbial taxa and functional guilds. We investigated the relationships of 11 fine root traits of 20 sub-arctic tundra meadow plant species and soil microbial community composition, using phospholipid fatty acids (PLFAs) and high-throughput sequencing. We primarily focused on the root economics spectrum, as it provides a useful framework to examine plant strategies by integrating the co-ordination of belowground root traits along a resource acquisition?conservation trade-off axis. We found that the chemical axis of the fine root economics spectrum was positively related to fungal to bacterial ratios, but negatively to Gram-positive to Gram-negative bacterial ratios. However, this spectrum was unrelated to the relative abundance of functional guilds of soil fungi. Nevertheless, the relative abundance of arbuscular mycorrhizal fungi was positively correlated to root carbon content, but negatively to the numbers of root forks per root length. Our results suggest that the fine root economics spectrum is important for predicting broader groups of soil microorganisms (i.e. fungi and bacteria), while individual root traits may be more important for predicting soil microbial taxa and functional guilds.},\n\tnumber = {3},\n\turldate = {2023-07-22},\n\tjournal = {New Phytologist},\n\tauthor = {Spitzer, Clydecia M. and Lindahl, Björn and Wardle, David A. and Sundqvist, Maja K. and Gundale, Michael J. and Fanin, Nicolas and Kardol, Paul},\n\tmonth = feb,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {fine root traits, fungi, plant–microorganism interactions, rhizosphere, tundra ecosystems},\n\tpages = {1508--1520},\n}\n\n\n\n\n\n Summary Fine roots, and their functional traits, influence associated rhizosphere microorganisms via root exudation and root litter quality. However, little information is known about their relationship with rhizosphere microbial taxa and functional guilds. We investigated the relationships of 11 fine root traits of 20 sub-arctic tundra meadow plant species and soil microbial community composition, using phospholipid fatty acids (PLFAs) and high-throughput sequencing. We primarily focused on the root economics spectrum, as it provides a useful framework to examine plant strategies by integrating the co-ordination of belowground root traits along a resource acquisition?conservation trade-off axis. We found that the chemical axis of the fine root economics spectrum was positively related to fungal to bacterial ratios, but negatively to Gram-positive to Gram-negative bacterial ratios. However, this spectrum was unrelated to the relative abundance of functional guilds of soil fungi. Nevertheless, the relative abundance of arbuscular mycorrhizal fungi was positively correlated to root carbon content, but negatively to the numbers of root forks per root length. Our results suggest that the fine root economics spectrum is important for predicting broader groups of soil microorganisms (i.e. fungi and bacteria), while individual root traits may be more important for predicting soil microbial taxa and functional guilds.\n
\n\n\n\n \n\n \n \n \n \n \n \n Nitrogen supply and physical disturbance shapes Arctic stream nitrogen uptake through effects on metabolic activity.\n \n \n \n \n\n\n \n Myrstener, M.; Thomas, S. A.; Giesler, R.; and Sponseller, R. A.\n\n\n \n\n\n\n Freshwater Biology, 66(8): 1502–1514. August 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{myrstener_nitrogen_2021,\n\ttitle = {Nitrogen supply and physical disturbance shapes {Arctic} stream nitrogen uptake through effects on metabolic activity},\n\tvolume = {66},\n\tissn = {0046-5070},\n\turl = {https://doi.org/10.1111/fwb.13734},\n\tdoi = {10.1111/fwb.13734},\n\tabstract = {Abstract Climate change in the Arctic is altering the delivery of nutrients from terrestrial to aquatic ecosystems. The impact of these changes on downstream lakes and rivers is influenced by the capacity of small streams to retain such inputs. Given the potential for nutrient limitation in oligotrophic Arctic streams, biotic demand should be high, unless harsh environmental conditions maintain low biomass standing stocks that limit nutrient uptake capacity. We assessed the drivers of nutrient uptake in two contrasting headwater environments in Arctic Sweden: one stream draining upland tundra and the other draining an alluvial valley with birch forest. At both sites, we measured nitrate (NO3?) uptake biweekly using short-term slug releases and estimated rates of gross primary production (GPP) and ecosystem respiration from continuous dissolved oxygen measurements. Catchment characteristics were associated with distinct stream chemical and biological properties. For example, the tundra stream maintained relatively low NO3? concentrations (average: 46 µg N/L) and rates of GPP (0.2 g O2 m?2 day?1). By comparison, the birch forest stream was more NO3? rich (88 µg N/L) and productive (GPP: 1.7 g O2 m?2 day?1). These differences corresponded to greater areal NO3? uptake rate and increased NO3? use efficiency (as uptake velocity) in the birch forest stream (max 192 µg N m?2 min?1 and 96 mm/hr) compared to its tundra counterpart (max 52 µg N m?2 min?1 and 49 mm/hr) during 2017. Further, different sets of environmental drivers predicted temporal patterns of nutrient uptake at these sites: abiotic factors (e.g. NO3? concentration and discharge) were associated with changes in uptake in the tundra stream, while metabolic activity was more important in the birch forest stream. Between sites, variation in uptake metrics suggests that the ability to retain pulses of nutrients is linked to nutrient supply regimes controlled at larger spatial and temporal scales and habitat properties that promote biomass accrual and thus biotic demand. Overall, constraints on biotic potential imposed by the habitat template determined the capacity of these high latitude streams to respond to future changes in nutrient inputs arising from climate warming or human land use. ?},\n\tnumber = {8},\n\turldate = {2023-07-22},\n\tjournal = {Freshwater Biology},\n\tauthor = {Myrstener, Maria and Thomas, Steven A. and Giesler, Reiner and Sponseller, Ryan A.},\n\tmonth = aug,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Arctic, catchment, metabolism, nutrient uptake, tundra},\n\tpages = {1502--1514},\n}\n\n\n\n\n\n Abstract Climate change in the Arctic is altering the delivery of nutrients from terrestrial to aquatic ecosystems. The impact of these changes on downstream lakes and rivers is influenced by the capacity of small streams to retain such inputs. Given the potential for nutrient limitation in oligotrophic Arctic streams, biotic demand should be high, unless harsh environmental conditions maintain low biomass standing stocks that limit nutrient uptake capacity. We assessed the drivers of nutrient uptake in two contrasting headwater environments in Arctic Sweden: one stream draining upland tundra and the other draining an alluvial valley with birch forest. At both sites, we measured nitrate (NO3?) uptake biweekly using short-term slug releases and estimated rates of gross primary production (GPP) and ecosystem respiration from continuous dissolved oxygen measurements. Catchment characteristics were associated with distinct stream chemical and biological properties. For example, the tundra stream maintained relatively low NO3? concentrations (average: 46 µg N/L) and rates of GPP (0.2 g O2 m?2 day?1). By comparison, the birch forest stream was more NO3? rich (88 µg N/L) and productive (GPP: 1.7 g O2 m?2 day?1). These differences corresponded to greater areal NO3? uptake rate and increased NO3? use efficiency (as uptake velocity) in the birch forest stream (max 192 µg N m?2 min?1 and 96 mm/hr) compared to its tundra counterpart (max 52 µg N m?2 min?1 and 49 mm/hr) during 2017. Further, different sets of environmental drivers predicted temporal patterns of nutrient uptake at these sites: abiotic factors (e.g. NO3? concentration and discharge) were associated with changes in uptake in the tundra stream, while metabolic activity was more important in the birch forest stream. Between sites, variation in uptake metrics suggests that the ability to retain pulses of nutrients is linked to nutrient supply regimes controlled at larger spatial and temporal scales and habitat properties that promote biomass accrual and thus biotic demand. Overall, constraints on biotic potential imposed by the habitat template determined the capacity of these high latitude streams to respond to future changes in nutrient inputs arising from climate warming or human land use. ?\n
\n\n\n\n \n\n \n \n \n \n \n \n The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study.\n \n \n \n \n\n\n \n Pascual, D.; Åkerman, J.; Becher, M.; Callaghan, T. V.; Christensen, T. R.; Dorrepaal, E.; Emanuelsson, U.; Giesler, R.; Hammarlund, D.; Hanna, E.; Hofgaard, A.; Jin, H.; Johansson, C.; Jonasson, C.; Klaminder, J.; Karlsson, J.; Lundin, E.; Michelsen, A.; Olefeldt, D.; Persson, A.; Phoenix, G. K.; Rączkowska, Z.; Rinnan, R.; Ström, L.; Tang, J.; Varner, R. K.; Wookey, P.; and Johansson, M.\n\n\n \n\n\n\n Ambio, 50(2): 375–392. February 2021.\n \n\n\n\n
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\n\n\n@article{pascual_missing_2021,\n\ttitle = {The missing pieces for better future predictions in subarctic ecosystems: {A} {Torneträsk} case study},\n\tvolume = {50},\n\tissn = {1654-7209},\n\turl = {https://doi.org/10.1007/s13280-020-01381-1},\n\tdoi = {10.1007/s13280-020-01381-1},\n\tabstract = {Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.},\n\tnumber = {2},\n\tjournal = {Ambio},\n\tauthor = {Pascual, Didac and Åkerman, Jonas and Becher, Marina and Callaghan, Terry V. and Christensen, Torben R. and Dorrepaal, Ellen and Emanuelsson, Urban and Giesler, Reiner and Hammarlund, Dan and Hanna, Edward and Hofgaard, Annika and Jin, Hongxiao and Johansson, Cecilia and Jonasson, Christer and Klaminder, Jonatan and Karlsson, Jan and Lundin, Erik and Michelsen, Anders and Olefeldt, David and Persson, Andreas and Phoenix, Gareth K. and Rączkowska, Zofia and Rinnan, Riikka and Ström, Lena and Tang, Jing and Varner, Ruth K. and Wookey, Philip and Johansson, Margareta},\n\tmonth = feb,\n\tyear = {2021},\n\tkeywords = {\\#nosource},\n\tpages = {375--392},\n}\n\n\n\n\n\n Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.\n
\n\n\n\n \n\n \n \n \n \n \n The seasonal dynamics of a High Arctic plant–visitor network: temporal observations and responses to delayed snow melt.\n \n \n \n\n\n \n Gillespie, M. A.; and Cooper, E. J\n\n\n \n\n\n\n Arctic Science, 8(3): 786–803. 2021.\n Publisher: Canadian Science Publishing 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7\n\n\n\n
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\n\n\n@article{gillespie_seasonal_2021,\n\ttitle = {The seasonal dynamics of a {High} {Arctic} plant–visitor network: temporal observations and responses to delayed snow melt},\n\tvolume = {8},\n\tdoi = {10.1139/as-2020-0056},\n\tabstract = {Plant - visitor food webs provide important insights into species interactions, and more information about their seasonal dynamics is vital to understanding the resilience of species to external pressures. Studies of Arctic networks can also improve our understanding of species responses to the pressures of climate change. This study provides the first description of a plant – insect visitor network in Svalbard, a High Arctic archipelago already experiencing the consequences of climate change. A subset of the network was collected from experimental plots where the snow melt date was delayed with snow fences. The deep snow plots delayed flowering and we expected this to disrupt plant-visitor interactions compared to ambient snow conditions. However, the composition of flowers and insect visitors were similar between regimes, and the network tracked patterns of overall flowering phenology. Nevertheless, the deep snow significantly reduced the average overlap between flower availability and insect activity, reducing the probability of an interaction. We suggest that at a landscape scale, Arctic pollinators will benefit from patchy changes to snow melt that maintain heterogeneity in the timing of flowering but changes that increase homogeneity in snowmelt across the landscape may negatively impact some species.},\n\tnumber = {3},\n\tjournal = {Arctic Science},\n\tauthor = {Gillespie, Mark AK and Cooper, Elisabeth J},\n\tyear = {2021},\n\tnote = {Publisher: Canadian Science Publishing 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7},\n\tkeywords = {\\#nosource},\n\tpages = {786--803},\n}\n\n\n\n\n\n Plant - visitor food webs provide important insights into species interactions, and more information about their seasonal dynamics is vital to understanding the resilience of species to external pressures. Studies of Arctic networks can also improve our understanding of species responses to the pressures of climate change. This study provides the first description of a plant – insect visitor network in Svalbard, a High Arctic archipelago already experiencing the consequences of climate change. A subset of the network was collected from experimental plots where the snow melt date was delayed with snow fences. The deep snow plots delayed flowering and we expected this to disrupt plant-visitor interactions compared to ambient snow conditions. However, the composition of flowers and insect visitors were similar between regimes, and the network tracked patterns of overall flowering phenology. Nevertheless, the deep snow significantly reduced the average overlap between flower availability and insect activity, reducing the probability of an interaction. We suggest that at a landscape scale, Arctic pollinators will benefit from patchy changes to snow melt that maintain heterogeneity in the timing of flowering but changes that increase homogeneity in snowmelt across the landscape may negatively impact some species.\n
\n\n\n\n \n\n \n \n \n \n \n \n Environmental drivers of Sphagnum growth in peatlands across the Holarctic region.\n \n \n \n \n\n\n \n Bengtsson, F.; Rydin, H.; Baltzer, J. L.; Bragazza, L.; Bu, Z.; Caporn, S. J. M.; Dorrepaal, E.; Flatberg, K. I.; Galanina, O.; Gałka, M.; Ganeva, A.; Goia, I.; Goncharova, N.; Hájek, M.; Haraguchi, A.; Harris, L. I.; Humphreys, E.; Jiroušek, M.; Kajukało, K.; Karofeld, E.; Koronatova, N. G.; Kosykh, N. P.; Laine, A. M.; Lamentowicz, M.; Lapshina, E.; Limpens, J.; Linkosalmi, M.; Ma, J.; Mauritz, M.; Mitchell, E. A. D.; Munir, T. M.; Natali, S. M.; Natcheva, R.; Payne, R. J.; Philippov, D. A.; Rice, S. K.; Robinson, S.; Robroek, B. J. M.; Rochefort, L.; Singer, D.; Stenøien, H. K.; Tuittila, E.; Vellak, K.; Waddington, J. M.; and Granath, G.\n\n\n \n\n\n\n Journal of Ecology, 109(1): 417–431. January 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{bengtsson_environmental_2021,\n\ttitle = {Environmental drivers of {Sphagnum} growth in peatlands across the {Holarctic} region},\n\tvolume = {109},\n\tissn = {0022-0477},\n\turl = {https://doi.org/10.1111/1365-2745.13499},\n\tdoi = {10.1111/1365-2745.13499},\n\tabstract = {Abstract The relative importance of global versus local environmental factors for growth and thus carbon uptake of the bryophyte genus Sphagnum?the main peat-former and ecosystem engineer in northern peatlands?remains unclear. We measured length growth and net primary production (NPP) of two abundant Sphagnum species across 99 Holarctic peatlands. We tested the importance of previously proposed abiotic and biotic drivers for peatland carbon uptake (climate, N deposition, water table depth and vascular plant cover) on these two responses. Employing structural equation models (SEMs), we explored both indirect and direct effects of drivers on Sphagnum growth. Variation in growth was large, but similar within and between peatlands. Length growth showed a stronger response to predictors than NPP. Moreover, the smaller and denser Sphagnum fuscum growing on hummocks had weaker responses to climatic variation than the larger and looser Sphagnum magellanicum growing in the wetter conditions. Growth decreased with increasing vascular plant cover within a site. Between sites, precipitation and temperature increased growth for S. magellanicum. The SEMs indicate that indirect effects are important. For example, vascular plant cover increased with a deeper water table, increased nitrogen deposition, precipitation and temperature. These factors also influenced Sphagnum growth indirectly by affecting moss shoot density. Synthesis. Our results imply that in a warmer climate, S. magellanicum will increase length growth as long as precipitation is not reduced, while S. fuscum is more resistant to decreased precipitation, but also less able to take advantage of increased precipitation and temperature. Such species-specific sensitivity to climate may affect competitive outcomes in a changing environment, and potentially the future carbon sink function of peatlands.},\n\tnumber = {1},\n\turldate = {2023-07-21},\n\tjournal = {Journal of Ecology},\n\tauthor = {Bengtsson, Fia and Rydin, Håkan and Baltzer, Jennifer L. and Bragazza, Luca and Bu, Zhao-Jun and Caporn, Simon J. M. and Dorrepaal, Ellen and Flatberg, Kjell Ivar and Galanina, Olga and Gałka, Mariusz and Ganeva, Anna and Goia, Irina and Goncharova, Nadezhda and Hájek, Michal and Haraguchi, Akira and Harris, Lorna I. and Humphreys, Elyn and Jiroušek, Martin and Kajukało, Katarzyna and Karofeld, Edgar and Koronatova, Natalia G. and Kosykh, Natalia P. and Laine, Anna M. and Lamentowicz, Mariusz and Lapshina, Elena and Limpens, Juul and Linkosalmi, Maiju and Ma, Jin-Ze and Mauritz, Marguerite and Mitchell, Edward A. D. and Munir, Tariq M. and Natali, Susan M. and Natcheva, Rayna and Payne, Richard J. and Philippov, Dmitriy A. and Rice, Steven K. and Robinson, Sean and Robroek, Bjorn J. M. and Rochefort, Line and Singer, David and Stenøien, Hans K. and Tuittila, Eeva-Stiina and Vellak, Kai and Waddington, James Michael and Granath, Gustaf},\n\tmonth = jan,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, PAR, climate, global change, net primary production, nitrogen deposition, peat mosses, plant–climate interactions, structural equation model},\n\tpages = {417--431},\n}\n\n\n\n\n\n Abstract The relative importance of global versus local environmental factors for growth and thus carbon uptake of the bryophyte genus Sphagnum?the main peat-former and ecosystem engineer in northern peatlands?remains unclear. We measured length growth and net primary production (NPP) of two abundant Sphagnum species across 99 Holarctic peatlands. We tested the importance of previously proposed abiotic and biotic drivers for peatland carbon uptake (climate, N deposition, water table depth and vascular plant cover) on these two responses. Employing structural equation models (SEMs), we explored both indirect and direct effects of drivers on Sphagnum growth. Variation in growth was large, but similar within and between peatlands. Length growth showed a stronger response to predictors than NPP. Moreover, the smaller and denser Sphagnum fuscum growing on hummocks had weaker responses to climatic variation than the larger and looser Sphagnum magellanicum growing in the wetter conditions. Growth decreased with increasing vascular plant cover within a site. Between sites, precipitation and temperature increased growth for S. magellanicum. The SEMs indicate that indirect effects are important. For example, vascular plant cover increased with a deeper water table, increased nitrogen deposition, precipitation and temperature. These factors also influenced Sphagnum growth indirectly by affecting moss shoot density. Synthesis. Our results imply that in a warmer climate, S. magellanicum will increase length growth as long as precipitation is not reduced, while S. fuscum is more resistant to decreased precipitation, but also less able to take advantage of increased precipitation and temperature. Such species-specific sensitivity to climate may affect competitive outcomes in a changing environment, and potentially the future carbon sink function of peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contribution of microbial photosynthesis to peatland carbon uptake along a latitudinal gradient.\n \n \n \n \n\n\n \n Hamard, S.; Céréghino, R.; Barret, M.; Sytiuk, A.; Lara, E.; Dorrepaal, E.; Kardol, P.; Küttim, M.; Lamentowicz, M.; Leflaive, J.; Le Roux, G.; Tuittila, E.; and Jassey, V. E. J.\n\n\n \n\n\n\n Journal of Ecology, 109(9): 3424–3441. September 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{hamard_contribution_2021,\n\ttitle = {Contribution of microbial photosynthesis to peatland carbon uptake along a latitudinal gradient},\n\tvolume = {109},\n\tissn = {0022-0477},\n\turl = {https://doi.org/10.1111/1365-2745.13732},\n\tdoi = {10.1111/1365-2745.13732},\n\tabstract = {Abstract Phototrophic microbes, also known as micro-algae, display a high abundance in many terrestrial surface soils. They contribute to atmospheric carbon dioxide fluxes through their photosynthesis, and thus regulate climate similar to plants. However, microbial photosynthesis remains overlooked in most terrestrial ecosystems. Here, we hypothesise that phototrophic microbes significantly contribute to peatland C uptake, unless environmental conditions limit their development and their photosynthetic activity. To test our hypothesis, we studied phototrophic microbial communities in five peatlands distributed along a latitudinal gradient in Europe. By means of metabarcoding, microscopy and cytometry analyses, as well as measures of photosynthesis, we investigated the diversity, absolute abundance and photosynthetic rates of the phototrophic microbial communities. We identified 351 photosynthetic prokaryotic and eukaryotic operational taxonomic units (OTUs) across the five peatlands. We found that water availability and plant composition were important determinants of the composition and the structure of phototrophic microbial communities. Despite environmental shifts in community structure and composition, we showed that microbial C fixation rates remained similar along the latitudinal gradient. Our results further revealed that phototrophic microbes accounted for approximately 10\\% of peatland C uptake. Synthesis. Our findings show that phototrophic microbes are extremely diverse and abundant in peatlands. While species turnover with environmental conditions, microbial photosynthesis similarly contributed to peatland C uptake at all latitudes. We estimate that phototrophic microbes take up around 75 MT CO2 per year in northern peatlands. This amount roughly equals the magnitude of projected peatland C loss due to climate warming and highlights the importance of phototrophic microbes for the peatland C cycle.},\n\tnumber = {9},\n\turldate = {2023-07-21},\n\tjournal = {Journal of Ecology},\n\tauthor = {Hamard, Samuel and Céréghino, Regis and Barret, Maialen and Sytiuk, Anna and Lara, Enrique and Dorrepaal, Ellen and Kardol, Paul and Küttim, Martin and Lamentowicz, Mariusz and Leflaive, Joséphine and Le Roux, Gaël and Tuittila, Eeva-Stiina and Jassey, Vincent E. J.},\n\tmonth = sep,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, algae, carbon cycle, metabarcoding, microbial diversity, peatland, photosynthesis, phototrophs, primary productivity},\n\tpages = {3424--3441},\n}\n\n\n\n\n\n Abstract Phototrophic microbes, also known as micro-algae, display a high abundance in many terrestrial surface soils. They contribute to atmospheric carbon dioxide fluxes through their photosynthesis, and thus regulate climate similar to plants. However, microbial photosynthesis remains overlooked in most terrestrial ecosystems. Here, we hypothesise that phototrophic microbes significantly contribute to peatland C uptake, unless environmental conditions limit their development and their photosynthetic activity. To test our hypothesis, we studied phototrophic microbial communities in five peatlands distributed along a latitudinal gradient in Europe. By means of metabarcoding, microscopy and cytometry analyses, as well as measures of photosynthesis, we investigated the diversity, absolute abundance and photosynthetic rates of the phototrophic microbial communities. We identified 351 photosynthetic prokaryotic and eukaryotic operational taxonomic units (OTUs) across the five peatlands. We found that water availability and plant composition were important determinants of the composition and the structure of phototrophic microbial communities. Despite environmental shifts in community structure and composition, we showed that microbial C fixation rates remained similar along the latitudinal gradient. Our results further revealed that phototrophic microbes accounted for approximately 10% of peatland C uptake. Synthesis. Our findings show that phototrophic microbes are extremely diverse and abundant in peatlands. While species turnover with environmental conditions, microbial photosynthesis similarly contributed to peatland C uptake at all latitudes. We estimate that phototrophic microbes take up around 75 MT CO2 per year in northern peatlands. This amount roughly equals the magnitude of projected peatland C loss due to climate warming and highlights the importance of phototrophic microbes for the peatland C cycle.\n
\n\n\n\n \n\n \n \n \n \n \n \n Mosses reduce soil nitrogen availability in a subarctic birch forest via effects on soil thermal regime and sequestration of deposited nitrogen.\n \n \n \n \n\n\n \n Koranda, M.; and Michelsen, A.\n\n\n \n\n\n\n Journal of Ecology, 109(3): 1424–1438. March 2021.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{koranda_mosses_2021,\n\ttitle = {Mosses reduce soil nitrogen availability in a subarctic birch forest via effects on soil thermal regime and sequestration of deposited nitrogen},\n\tvolume = {109},\n\tissn = {0022-0477},\n\turl = {https://doi.org/10.1111/1365-2745.13567},\n\tdoi = {10.1111/1365-2745.13567},\n\tabstract = {Abstract In high-latitude ecosystems bryophytes are important drivers of ecosystem functions. Alterations in abundance of mosses due to global change may thus strongly influence carbon (C) and nitrogen (N) cycling and hence cause feedback on climate. The effects of mosses on soil microbial activity are, however, still poorly understood. Our study aims at elucidating how and by which mechanisms bryophytes influence microbial decomposition processes of soil organic matter and thus soil nutrient availability. We present results from a field experiment in a subarctic birch forest in northern Sweden, where we partly removed the moss cover and replaced it with an artificial soil cover for simulating moss effects on soil temperature and moisture. We combined this with a fertilization experiment with 15N-labelled N for analysing the effects of moss N sequestration on soil processes. Our results demonstrate the capacity of mosses to reduce soil N availability and retard N cycling. The comparison with artificial soil cover plots suggests that the effect of mosses on N cycling is linked to the thermal insulation capacity of mosses causing low average soil temperature in summer and strongly reduced soil temperature fluctuations, the latter also leading to a decreased frequency of freeze-thaw events in autumn and spring. Our results also showed, however, that the negative temperature effect of mosses on soil microbial activity was in part compensated by stimulatory effects of the moss layer, possibly linked to leaching of labile substrates from the moss. Furthermore, our results revealed that bryophytes efficiently sequester added N from wet deposition and thus prevent effects of increased atmospheric N deposition on soil N availability and soil processes. Synthesis. Our study emphasizes the important role of mosses in carbon and nutrient cycling in high-latitude ecosystems and the potential strong impacts of reductions in moss abundance on microbial decomposition processes and nutrient availability in subarctic and boreal forests.},\n\tnumber = {3},\n\turldate = {2023-07-21},\n\tjournal = {Journal of Ecology},\n\tauthor = {Koranda, Marianne and Michelsen, Anders},\n\tmonth = mar,\n\tyear = {2021},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, bryophytes, extracellular enzyme activities, microbial communities, microbial processes, moss, nitrogen availability, nitrogen cycling, soil temperature},\n\tpages = {1424--1438},\n}\n\n\n\n\n\n Abstract In high-latitude ecosystems bryophytes are important drivers of ecosystem functions. Alterations in abundance of mosses due to global change may thus strongly influence carbon (C) and nitrogen (N) cycling and hence cause feedback on climate. The effects of mosses on soil microbial activity are, however, still poorly understood. Our study aims at elucidating how and by which mechanisms bryophytes influence microbial decomposition processes of soil organic matter and thus soil nutrient availability. We present results from a field experiment in a subarctic birch forest in northern Sweden, where we partly removed the moss cover and replaced it with an artificial soil cover for simulating moss effects on soil temperature and moisture. We combined this with a fertilization experiment with 15N-labelled N for analysing the effects of moss N sequestration on soil processes. Our results demonstrate the capacity of mosses to reduce soil N availability and retard N cycling. The comparison with artificial soil cover plots suggests that the effect of mosses on N cycling is linked to the thermal insulation capacity of mosses causing low average soil temperature in summer and strongly reduced soil temperature fluctuations, the latter also leading to a decreased frequency of freeze-thaw events in autumn and spring. Our results also showed, however, that the negative temperature effect of mosses on soil microbial activity was in part compensated by stimulatory effects of the moss layer, possibly linked to leaching of labile substrates from the moss. Furthermore, our results revealed that bryophytes efficiently sequester added N from wet deposition and thus prevent effects of increased atmospheric N deposition on soil N availability and soil processes. Synthesis. Our study emphasizes the important role of mosses in carbon and nutrient cycling in high-latitude ecosystems and the potential strong impacts of reductions in moss abundance on microbial decomposition processes and nutrient availability in subarctic and boreal forests.\n
\n\n\n\n \n\n \n \n \n \n \n \n Diel Variability of CO2 Emissions From Northern Lakes.\n \n \n \n \n\n\n \n Rudberg, D.; Duc, N. T.; Schenk, J.; Sieczko, A. K.; Pajala, G.; Sawakuchi, H. O.; Verheijen, H. A.; Melack, J. M.; MacIntyre, S.; Karlsson, J.; and Bastviken, D.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 126(10): e2021JG006246. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021JG006246\n\n\n\n
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\n\n\n@article{rudberg_diel_2021,\n\ttitle = {Diel {Variability} of {CO2} {Emissions} {From} {Northern} {Lakes}},\n\tvolume = {126},\n\tcopyright = {© 2021. The Authors.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JG006246},\n\tdoi = {10.1029/2021JG006246},\n\tabstract = {Lakes are generally supersaturated in carbon dioxide (CO2) and emitters of CO2 to the atmosphere. However, estimates of CO2 flux () from lakes are seldom based on direct flux measurements and usually do not account for nighttime emissions, yielding risk of biased assessments. Here, we present direct measurements from automated floating chambers collected every 2–3 hr and spanning 115 24 hr periods in three boreal lakes during summer stratification and before and after autumn mixing in the most eutrophic lake of these. We observed 40\\%–67\\% higher mean in daytime during periods of surface water CO2 supersaturation in all lakes. Day-night differences in wind speed were correlated with the day-night differences in the two larger lakes, but in the smallest and most wind-sheltered lake peaks of coincided with low-winds at night. During stratification in the eutrophic lake, CO2 was near equilibrium and diel variability of insignificant, but after autumn mixing was high with distinct diel variability making this lake a net CO2 source on an annual basis. We found that extrapolating daytime measurements to 24 hr periods overestimated by up to 30\\%, whereas extrapolating measurements from the stratified period to annual rates in the eutrophic lake underestimated by 86\\%. This shows the importance of accounting for diel and seasonal variability in lake CO2 emission estimates.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2023-07-20},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Rudberg, D. and Duc, N. T. and Schenk, J. and Sieczko, A. K. and Pajala, G. and Sawakuchi, H. O. and Verheijen, H. A. and Melack, J. M. and MacIntyre, S. and Karlsson, J. and Bastviken, D.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021JG006246},\n\tkeywords = {\\#nosource, automated flux chambers, autumn mixing, carbon dioxide fluxes, diel variability, lake greenhouse gas emissions},\n\tpages = {e2021JG006246},\n}\n\n\n\n\n\n Lakes are generally supersaturated in carbon dioxide (CO2) and emitters of CO2 to the atmosphere. However, estimates of CO2 flux () from lakes are seldom based on direct flux measurements and usually do not account for nighttime emissions, yielding risk of biased assessments. Here, we present direct measurements from automated floating chambers collected every 2–3 hr and spanning 115 24 hr periods in three boreal lakes during summer stratification and before and after autumn mixing in the most eutrophic lake of these. We observed 40%–67% higher mean in daytime during periods of surface water CO2 supersaturation in all lakes. Day-night differences in wind speed were correlated with the day-night differences in the two larger lakes, but in the smallest and most wind-sheltered lake peaks of coincided with low-winds at night. During stratification in the eutrophic lake, CO2 was near equilibrium and diel variability of insignificant, but after autumn mixing was high with distinct diel variability making this lake a net CO2 source on an annual basis. We found that extrapolating daytime measurements to 24 hr periods overestimated by up to 30%, whereas extrapolating measurements from the stratified period to annual rates in the eutrophic lake underestimated by 86%. This shows the importance of accounting for diel and seasonal variability in lake CO2 emission estimates.\n
\n\n\n\n \n\n \n \n \n \n \n \n Phosphorus Regulation of Methane Oxidation in Water From Ice-Covered Lakes.\n \n \n \n \n\n\n \n Sawakuchi, H. O.; Martin, G.; Peura, S.; Bertilsson, S.; Karlsson, J.; and Bastviken, D.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 126(9): e2020JG006190. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG006190\n\n\n\n
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\n\n\n@article{sawakuchi_phosphorus_2021,\n\ttitle = {Phosphorus {Regulation} of {Methane} {Oxidation} in {Water} {From} {Ice}-{Covered} {Lakes}},\n\tvolume = {126},\n\tcopyright = {© 2021. The Authors.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020JG006190},\n\tdoi = {10.1029/2020JG006190},\n\tabstract = {Winter methane (CH4) accumulation in seasonally ice-covered lakes can contribute to large episodic emissions to the atmosphere during spring ice melt. Biological methane oxidation can significantly mitigate such CH4 emissions, but despite favorable CH4 and O2 concentrations, CH4 oxidation appears constrained in some lakes for unknown reasons. Here we experimentally test the hypothesis that phosphorus (P) availability is limiting CH4 oxidation, resulting in differences in ice-out emissions among lakes. We observed a positive relationship between potential CH4 oxidation and P concentration across 12 studied lakes and found an increase in CH4 oxidation in response to P amendment, without any parallel change in the methanotrophic community composition. Hence, while an increase in sedimentary CH4 production and ebullitive emissions may happen with eutrophication, our study indicates that the increase in P associated with eutrophication may also enhance CH4 oxidation. The increase in CH4 oxidation may hence play an important role in nutrient-rich ice-covered lakes where bubbles trapped under the ice may to a greater extent be oxidized, reducing the ice-out emissions of CH4. This may be an important factor regulating CH4 emissions from high latitude lakes.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2023-07-20},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Sawakuchi, Henrique O. and Martin, Gaëtan and Peura, Sari and Bertilsson, Stefan and Karlsson, Jan and Bastviken, David},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG006190},\n\tkeywords = {\\#nosource, CH4 oxidation, boreal lakes, ice-out CH4 emissions, methanotrophs, phosphorus},\n\tpages = {e2020JG006190},\n}\n\n\n\n\n\n Winter methane (CH4) accumulation in seasonally ice-covered lakes can contribute to large episodic emissions to the atmosphere during spring ice melt. Biological methane oxidation can significantly mitigate such CH4 emissions, but despite favorable CH4 and O2 concentrations, CH4 oxidation appears constrained in some lakes for unknown reasons. Here we experimentally test the hypothesis that phosphorus (P) availability is limiting CH4 oxidation, resulting in differences in ice-out emissions among lakes. We observed a positive relationship between potential CH4 oxidation and P concentration across 12 studied lakes and found an increase in CH4 oxidation in response to P amendment, without any parallel change in the methanotrophic community composition. Hence, while an increase in sedimentary CH4 production and ebullitive emissions may happen with eutrophication, our study indicates that the increase in P associated with eutrophication may also enhance CH4 oxidation. The increase in CH4 oxidation may hence play an important role in nutrient-rich ice-covered lakes where bubbles trapped under the ice may to a greater extent be oxidized, reducing the ice-out emissions of CH4. This may be an important factor regulating CH4 emissions from high latitude lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n When does temperature matter for ecosystem respiration?.\n \n \n \n \n\n\n \n Gudasz, C.; Karlsson, J.; and Bastviken, D.\n\n\n \n\n\n\n Environmental Research Communications, 3(12): 121001. December 2021.\n Publisher: IOP Publishing\n\n\n\n
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\n\n\n@article{gudasz_when_2021,\n\ttitle = {When does temperature matter for ecosystem respiration?},\n\tvolume = {3},\n\tissn = {2515-7620},\n\turl = {https://dx.doi.org/10.1088/2515-7620/ac3b9f},\n\tdoi = {10.1088/2515-7620/ac3b9f},\n\tabstract = {The temperature response of ecosystem processes is key to understand and predict impacts of climate change. This is especially true for respiration, given its high temperature sensitivity and major role in the global carbon cycle. However, similar intrinsic temperature sensitivity for respiration does not mean comparable temperature effects across ecosystems and biomes because non-temperature factors can be more important. Here we analyzed soil and sediment respiration data and found that in temperature ranges corresponding to high latitude mean temperatures, absolute respiration rates are more sensitive to non-temperature factors than to projected direct temperature effects. However, at higher temperatures ({\\textgreater}20 °C) the direct effect of temperature mediated by temperature sensitivity will likely be more important over changes in non-temperature factors in shaping how respiration change over time. This supports past suggestions that the relatively small projected temperature increase at low (tropical) latitudes may have a large direct impact on absolute respiration. In contrast, absolute respiration rates at high (boreal/arctic) latitudes will likely be more sensitive on the development of the non-temperature factors than on the direct effects of the large projected temperature increase there. Social media abstract. Respiration may be less dependent to changes in temperature at higher than lower latitudes.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2023-07-20},\n\tjournal = {Environmental Research Communications},\n\tauthor = {Gudasz, Cristian and Karlsson, Jan and Bastviken, David},\n\tmonth = dec,\n\tyear = {2021},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {121001},\n}\n\n\n\n\n\n The temperature response of ecosystem processes is key to understand and predict impacts of climate change. This is especially true for respiration, given its high temperature sensitivity and major role in the global carbon cycle. However, similar intrinsic temperature sensitivity for respiration does not mean comparable temperature effects across ecosystems and biomes because non-temperature factors can be more important. Here we analyzed soil and sediment respiration data and found that in temperature ranges corresponding to high latitude mean temperatures, absolute respiration rates are more sensitive to non-temperature factors than to projected direct temperature effects. However, at higher temperatures (\\textgreater20 °C) the direct effect of temperature mediated by temperature sensitivity will likely be more important over changes in non-temperature factors in shaping how respiration change over time. This supports past suggestions that the relatively small projected temperature increase at low (tropical) latitudes may have a large direct impact on absolute respiration. In contrast, absolute respiration rates at high (boreal/arctic) latitudes will likely be more sensitive on the development of the non-temperature factors than on the direct effects of the large projected temperature increase there. Social media abstract. Respiration may be less dependent to changes in temperature at higher than lower latitudes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Sizable carbon emission from the floodplain of Ob River.\n \n \n \n \n\n\n \n Krickov, I. V.; Serikova, S.; Pokrovsky, O. S.; Vorobyev, S. N.; Lim, A. G.; Siewert, M. B.; and Karlsson, J.\n\n\n \n\n\n\n Ecological Indicators, 131: 108164. November 2021.\n \n\n\n\n
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\n\n\n@article{krickov_sizable_2021,\n\ttitle = {Sizable carbon emission from the floodplain of {Ob} {River}},\n\tvolume = {131},\n\tissn = {1470-160X},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1470160X21008293},\n\tdoi = {10.1016/j.ecolind.2021.108164},\n\tabstract = {The Ob River floodplain is the second largest floodplain in the world. Despite its vast area, estimates of carbon (C) emissions from the Ob River floodplain are largely absent. Here we present seasonal C emission and water area extent from the main channel and the floodplain along a {\\textasciitilde}4 km reach in the boreal zone of the Ob River. We found strong seasonality in water area extent of the Ob main channel ({\\textasciitilde}1.8 km2) and floodplain ({\\textasciitilde}3 km2) with water covering 34\\% of land during flood and subsequently declining to {\\textasciitilde}16\\% and {\\textasciitilde}14\\% during summer and autumn baseflow, respectively. The C emissions also varied seasonally over the open water period, ranging from −0.1 to 0.6 g C m−2 d−1 for the Ob main channel and from 0 to 9 g C m−2 d−1 for the floodplain. The dissolved organic carbon positively affected CO2 concentrations and fluxes in the floodplain during all seasons, whereas pH and oxygen concentration negatively impacted CO2 concentrations and fluxes. Some nutrients (ammonia and phosphate) positively correlated with CO2 and CH4 concentrations in summer. The total C emission from the study reach (1.8 km2 main channel, 3 km2 floodplain) during moderate flooding was 236 ± 51 tons C yr−1 ({\\textgreater}99\\% CO2, {\\textless}1\\% CH4) with the floodplain accounting for {\\textasciitilde}65\\%. The contribution of the floodplain to the net river C evasion may be even greater during years of high flooding and in northern regions of the Ob River basin, where floodplain soils are more C-rich and are underlain by permafrost, and in years with more extensive flooding.},\n\tlanguage = {en},\n\turldate = {2021-10-28},\n\tjournal = {Ecological Indicators},\n\tauthor = {Krickov, Ivan V. and Serikova, Svetlana and Pokrovsky, Oleg S. and Vorobyev, Sergey N. and Lim, Artem G. and Siewert, Matthias B. and Karlsson, Jan},\n\tmonth = nov,\n\tyear = {2021},\n\tkeywords = {\\#nosource, Carbon emission, Floodplain, Greenhouse gases, Ob river, Seasonal influences},\n\tpages = {108164},\n}\n\n\n\n\n\n The Ob River floodplain is the second largest floodplain in the world. Despite its vast area, estimates of carbon (C) emissions from the Ob River floodplain are largely absent. Here we present seasonal C emission and water area extent from the main channel and the floodplain along a ~4 km reach in the boreal zone of the Ob River. We found strong seasonality in water area extent of the Ob main channel (~1.8 km2) and floodplain (~3 km2) with water covering 34% of land during flood and subsequently declining to ~16% and ~14% during summer and autumn baseflow, respectively. The C emissions also varied seasonally over the open water period, ranging from −0.1 to 0.6 g C m−2 d−1 for the Ob main channel and from 0 to 9 g C m−2 d−1 for the floodplain. The dissolved organic carbon positively affected CO2 concentrations and fluxes in the floodplain during all seasons, whereas pH and oxygen concentration negatively impacted CO2 concentrations and fluxes. Some nutrients (ammonia and phosphate) positively correlated with CO2 and CH4 concentrations in summer. The total C emission from the study reach (1.8 km2 main channel, 3 km2 floodplain) during moderate flooding was 236 ± 51 tons C yr−1 (\\textgreater99% CO2, \\textless1% CH4) with the floodplain accounting for ~65%. The contribution of the floodplain to the net river C evasion may be even greater during years of high flooding and in northern regions of the Ob River basin, where floodplain soils are more C-rich and are underlain by permafrost, and in years with more extensive flooding.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of a long-term anoxic warming scenario on microbial community structure and functional potential of permafrost-affected soil.\n \n \n \n \n\n\n \n Yang, S.; Liebner, S.; Walz, J.; Knoblauch, C.; Bornemann, T. L. V.; Probst, A. J.; Wagner, D.; Jetten, M. S. M.; and in ‘t Zandt, M. H.\n\n\n \n\n\n\n Permafrost and Periglacial Processes, 32(4): 641–656. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.2131\n\n\n\n
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\n\n\n@article{yang_effects_2021,\n\ttitle = {Effects of a long-term anoxic warming scenario on microbial community structure and functional potential of permafrost-affected soil},\n\tvolume = {32},\n\tissn = {1099-1530},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ppp.2131},\n\tdoi = {10.1002/ppp.2131},\n\tabstract = {Permafrost (PF)-affected soils are widespread in the Arctic and store about half the global soil organic carbon. This large carbon pool becomes vulnerable to microbial decomposition through PF warming and deepening of the seasonal thaw layer (active layer [AL]). Here we combined greenhouse gas (GHG) production rate measurements with a metagenome-based assessment of the microbial taxonomic and metabolic potential before and after 5 years of incubation under anoxic conditions at a constant temperature of 4°C in the AL, PF transition layer, and intact PF. Warming led to a rapid initial release of CO2 and, to a lesser extent, CH4 in all layers. After the initial pulse, especially in CO2 production, GHG production rates declined and conditions became more methanogenic. Functional gene-based analyses indicated a decrease in carbon- and nitrogen-cycling genes and a community shift to the degradation of less-labile organic matter. This study reveals low but continuous GHG production in long-term warming scenarios, which coincides with a decrease in the relative abundance of major metabolic pathway genes and an increase in carbohydrate-active enzyme classes.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2021-10-28},\n\tjournal = {Permafrost and Periglacial Processes},\n\tauthor = {Yang, Sizhong and Liebner, Susanne and Walz, Josefine and Knoblauch, Christian and Bornemann, Till L. V. and Probst, Alexander J. and Wagner, Dirk and Jetten, Mike S. M. and in ‘t Zandt, Michiel H.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.2131},\n\tkeywords = {\\#nosource, climate change, greenhouse gases, microbial dynamics, permafrost},\n\tpages = {641--656},\n}\n\n\n\n\n\n Permafrost (PF)-affected soils are widespread in the Arctic and store about half the global soil organic carbon. This large carbon pool becomes vulnerable to microbial decomposition through PF warming and deepening of the seasonal thaw layer (active layer [AL]). Here we combined greenhouse gas (GHG) production rate measurements with a metagenome-based assessment of the microbial taxonomic and metabolic potential before and after 5 years of incubation under anoxic conditions at a constant temperature of 4°C in the AL, PF transition layer, and intact PF. Warming led to a rapid initial release of CO2 and, to a lesser extent, CH4 in all layers. After the initial pulse, especially in CO2 production, GHG production rates declined and conditions became more methanogenic. Functional gene-based analyses indicated a decrease in carbon- and nitrogen-cycling genes and a community shift to the degradation of less-labile organic matter. This study reveals low but continuous GHG production in long-term warming scenarios, which coincides with a decrease in the relative abundance of major metabolic pathway genes and an increase in carbohydrate-active enzyme classes.\n
\n\n\n\n \n\n \n \n \n \n \n \n UAV reveals substantial but heterogeneous effects of herbivores on Arctic vegetation.\n \n \n \n \n\n\n \n Siewert, M. B.; and Olofsson, J.\n\n\n \n\n\n\n Scientific Reports, 11(1): 19468. September 2021.\n Bandiera_abtest: a Cc_license_type: cc_by Cg_type: Nature Research Journals Number: 1 Primary_atype: Research Publisher: Nature Publishing Group Subject_term: Climate-change ecology;Ecosystem ecology Subject_term_id: climate-change-ecology;ecosystem-ecology\n\n\n\n
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\n\n\n@article{siewert_uav_2021,\n\ttitle = {{UAV} reveals substantial but heterogeneous effects of herbivores on {Arctic} vegetation},\n\tvolume = {11},\n\tcopyright = {2021 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-021-98497-5},\n\tdoi = {10.1038/s41598-021-98497-5},\n\tabstract = {Understanding how herbivores shape plant biomass and distribution is a core challenge in ecology. Yet, the lack of suitable remote sensing technology limits our knowledge of temporal and spatial impacts of mammal herbivores in the Earth system. The regular interannual density fluctuations of voles and lemmings are exceptional with their large reduction of plant biomass in Arctic landscapes during peak years (12–24\\%) as previously shown at large spatial scales using satellites. This provides evidence that herbivores are important drivers of observed global changes in vegetation productivity. Here, we use a novel approach with repeated unmanned aerial vehicle (UAV) flights, to map vegetation impact by rodents, indicating that many important aspects of vegetation dynamics otherwise hidden by the coarse resolution of satellite images, including plant–herbivore interactions, can be revealed using UAVs. We quantify areas impacted by rodents at four complex Arctic landscapes with very high spatial resolution UAV imagery to get a new perspective on how herbivores shape Arctic ecosystems. The area impacted by voles and lemmings is indeed substantial, larger at higher altitude tundra environments, varies between habitats depending on local snow cover and plant community composition, and is heterogeneous even within habitats at submeter scales. Coupling this with spectral reflectance of vegetation (NDVI), we can show that the impact on central ecosystem properties like GPP and biomass is stronger than currently accounted for in Arctic ecosystems. As an emerging technology, UAVs will allow us to better disentangle important information on how herbivores maintain spatial heterogeneity, function and diversity in natural ecosystems.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2021-10-28},\n\tjournal = {Scientific Reports},\n\tauthor = {Siewert, Matthias B. and Olofsson, Johan},\n\tmonth = sep,\n\tyear = {2021},\n\tnote = {Bandiera\\_abtest: a\nCc\\_license\\_type: cc\\_by\nCg\\_type: Nature Research Journals\nNumber: 1\nPrimary\\_atype: Research\nPublisher: Nature Publishing Group\nSubject\\_term: Climate-change ecology;Ecosystem ecology\nSubject\\_term\\_id: climate-change-ecology;ecosystem-ecology},\n\tkeywords = {\\#nosource, Climate-change ecology, Ecosystem ecology},\n\tpages = {19468},\n}\n\n\n\n\n\n Understanding how herbivores shape plant biomass and distribution is a core challenge in ecology. Yet, the lack of suitable remote sensing technology limits our knowledge of temporal and spatial impacts of mammal herbivores in the Earth system. The regular interannual density fluctuations of voles and lemmings are exceptional with their large reduction of plant biomass in Arctic landscapes during peak years (12–24%) as previously shown at large spatial scales using satellites. This provides evidence that herbivores are important drivers of observed global changes in vegetation productivity. Here, we use a novel approach with repeated unmanned aerial vehicle (UAV) flights, to map vegetation impact by rodents, indicating that many important aspects of vegetation dynamics otherwise hidden by the coarse resolution of satellite images, including plant–herbivore interactions, can be revealed using UAVs. We quantify areas impacted by rodents at four complex Arctic landscapes with very high spatial resolution UAV imagery to get a new perspective on how herbivores shape Arctic ecosystems. The area impacted by voles and lemmings is indeed substantial, larger at higher altitude tundra environments, varies between habitats depending on local snow cover and plant community composition, and is heterogeneous even within habitats at submeter scales. Coupling this with spectral reflectance of vegetation (NDVI), we can show that the impact on central ecosystem properties like GPP and biomass is stronger than currently accounted for in Arctic ecosystems. As an emerging technology, UAVs will allow us to better disentangle important information on how herbivores maintain spatial heterogeneity, function and diversity in natural ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Patterns and Variation of Littoral Habitat Size Among Lakes.\n \n \n \n \n\n\n \n Seekell, D.; Cael, B.; Norman, S.; and Byström, P.\n\n\n \n\n\n\n Geophysical Research Letters, 48(20): e2021GL095046. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GL095046\n\n\n\n
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\n\n\n@article{seekell_patterns_2021,\n\ttitle = {Patterns and {Variation} of {Littoral} {Habitat} {Size} {Among} {Lakes}},\n\tvolume = {48},\n\tissn = {1944-8007},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021GL095046},\n\tdoi = {10.1029/2021GL095046},\n\tabstract = {The littoral zone varies in size among lakes from ∼3\\% to 100\\% of lake surface area. In this paper, we derive a simple theoretical scaling relationship that explains this variation, and test this theory using bathymetric data across the size spectra of freshwater lakes (surface area = 0.01–82,103 km2, maximum depth = 2–1,741 m). Littoral area primarily reflects the ratio of the maximum depth of photosynthesis to maximum lake depth. However, lakes that are similar in these characteristics can have different relative littoral areas because of variation in basin shape. Hypsometric (area-elevation) models that describe these patterns for individual lakes can be generalized among lakes to accurately predict the relative size of littoral habitat when there is incomplete bathymetric information. Collectively, our results provide simple rules for understanding patterns of littoral habitat size at the regional and global scales.},\n\tlanguage = {en},\n\tnumber = {20},\n\turldate = {2021-10-28},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Seekell, D. and Cael, B. and Norman, S. and Byström, P.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2021GL095046},\n\tkeywords = {\\#nosource, hypsometry, lake morphometry, light penetration, littoral zone, scaling},\n\tpages = {e2021GL095046},\n}\n\n\n\n\n\n The littoral zone varies in size among lakes from ∼3% to 100% of lake surface area. In this paper, we derive a simple theoretical scaling relationship that explains this variation, and test this theory using bathymetric data across the size spectra of freshwater lakes (surface area = 0.01–82,103 km2, maximum depth = 2–1,741 m). Littoral area primarily reflects the ratio of the maximum depth of photosynthesis to maximum lake depth. However, lakes that are similar in these characteristics can have different relative littoral areas because of variation in basin shape. Hypsometric (area-elevation) models that describe these patterns for individual lakes can be generalized among lakes to accurately predict the relative size of littoral habitat when there is incomplete bathymetric information. Collectively, our results provide simple rules for understanding patterns of littoral habitat size at the regional and global scales.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global CO2 fertilization of Sphagnum peat mosses via suppression of photorespiration during the twentieth century.\n \n \n \n \n\n\n \n Serk, H.; Nilsson, M. B.; Bohlin, E.; Ehlers, I.; Wieloch, T.; Olid, C.; Grover, S.; Kalbitz, K.; Limpens, J.; Moore, T.; Münchberger, W.; Talbot, J.; Wang, X.; Knorr, K.; Pancotto, V.; and Schleucher, J.\n\n\n \n\n\n\n Scientific Reports, 11(1): 24517. December 2021.\n Bandiera_abtest: a Cc_license_type: cc_by Cg_type: Nature Research Journals Number: 1 Primary_atype: Research Publisher: Nature Publishing Group Subject_term: Biochemistry;Biogeochemistry;Biophysics;Chemical biology;Climate sciences;Ecology;Environmental sciences;Plant sciences Subject_term_id: biochemistry;biogeochemistry;biophysics;chemical-biology;climate-sciences;ecology;environmental-sciences;plant-sciences\n\n\n\n
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\n\n\n@article{serk_global_2021,\n\ttitle = {Global {CO2} fertilization of {Sphagnum} peat mosses via suppression of photorespiration during the twentieth century},\n\tvolume = {11},\n\tcopyright = {2021 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-021-02953-1},\n\tdoi = {10.1038/s41598-021-02953-1},\n\tabstract = {Natural peatlands contribute significantly to global carbon sequestration and storage of biomass, most of which derives from Sphagnum peat mosses. Atmospheric CO2 levels have increased dramatically during the twentieth century, from 280 to {\\textgreater} 400 ppm, which has affected plant carbon dynamics. Net carbon assimilation is strongly reduced by photorespiration, a process that depends on the CO2 to O2 ratio. Here we investigate the response of the photorespiration to photosynthesis ratio in Sphagnum mosses to recent CO2 increases by comparing deuterium isotopomers of historical and contemporary Sphagnum tissues collected from 36 peat cores from five continents. Rising CO2 levels generally suppressed photorespiration relative to photosynthesis but the magnitude of suppression depended on the current water table depth. By estimating the changes in water table depth, temperature, and precipitation during the twentieth century, we excluded potential effects of these climate parameters on the observed isotopomer responses. Further, we showed that the photorespiration to photosynthesis ratio varied between Sphagnum subgenera, indicating differences in their photosynthetic capacity. The global suppression of photorespiration in Sphagnum suggests an increased net primary production potential in response to the ongoing rise in atmospheric CO2, in particular for mire structures with intermediate water table depths.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2022-01-20},\n\tjournal = {Scientific Reports},\n\tauthor = {Serk, Henrik and Nilsson, Mats B. and Bohlin, Elisabet and Ehlers, Ina and Wieloch, Thomas and Olid, Carolina and Grover, Samantha and Kalbitz, Karsten and Limpens, Juul and Moore, Tim and Münchberger, Wiebke and Talbot, Julie and Wang, Xianwei and Knorr, Klaus-Holger and Pancotto, Verónica and Schleucher, Jürgen},\n\tmonth = dec,\n\tyear = {2021},\n\tnote = {Bandiera\\_abtest: a\nCc\\_license\\_type: cc\\_by\nCg\\_type: Nature Research Journals\nNumber: 1\nPrimary\\_atype: Research\nPublisher: Nature Publishing Group\nSubject\\_term: Biochemistry;Biogeochemistry;Biophysics;Chemical biology;Climate sciences;Ecology;Environmental sciences;Plant sciences\nSubject\\_term\\_id: biochemistry;biogeochemistry;biophysics;chemical-biology;climate-sciences;ecology;environmental-sciences;plant-sciences},\n\tkeywords = {\\#nosource, Biochemistry, Biogeochemistry, Biophysics, Chemical biology, Climate sciences, Ecology, Environmental sciences, Plant sciences},\n\tpages = {24517},\n}\n\n\n\n\n\n Natural peatlands contribute significantly to global carbon sequestration and storage of biomass, most of which derives from Sphagnum peat mosses. Atmospheric CO2 levels have increased dramatically during the twentieth century, from 280 to \\textgreater 400 ppm, which has affected plant carbon dynamics. Net carbon assimilation is strongly reduced by photorespiration, a process that depends on the CO2 to O2 ratio. Here we investigate the response of the photorespiration to photosynthesis ratio in Sphagnum mosses to recent CO2 increases by comparing deuterium isotopomers of historical and contemporary Sphagnum tissues collected from 36 peat cores from five continents. Rising CO2 levels generally suppressed photorespiration relative to photosynthesis but the magnitude of suppression depended on the current water table depth. By estimating the changes in water table depth, temperature, and precipitation during the twentieth century, we excluded potential effects of these climate parameters on the observed isotopomer responses. Further, we showed that the photorespiration to photosynthesis ratio varied between Sphagnum subgenera, indicating differences in their photosynthetic capacity. The global suppression of photorespiration in Sphagnum suggests an increased net primary production potential in response to the ongoing rise in atmospheric CO2, in particular for mire structures with intermediate water table depths.\n
\n\n\n\n \n\n \n \n \n \n \n \n How does a wetland plant respond to increasing temperature along a latitudinal gradient?.\n \n \n \n \n\n\n \n Lindborg, R.; Ermold, M.; Kuglerová, L.; Jansson, R.; Larson, K. W.; Milbau, A.; and Cousins, S. A. O.\n\n\n \n\n\n\n Ecology and Evolution, 11(22): 16228–16238. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.8303\n\n\n\n
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\n\n\n@article{lindborg_how_2021,\n\ttitle = {How does a wetland plant respond to increasing temperature along a latitudinal gradient?},\n\tvolume = {11},\n\tissn = {2045-7758},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.8303},\n\tdoi = {10.1002/ece3.8303},\n\tabstract = {Global warming affects plant fitness through changes in functional traits and thereby ecosystem function. Wetlands are declining worldwide, and hence, ecosystem functions linked to wetlands are threatened. We use Caltha palustris “a common wetland plant” to study whether warming affects growth and reproduction differently depending on origin of source population, potentially affecting phenotypic response to local climate. We conducted a 2-year in situ temperature manipulation experiment using clone pairs of C. palustris in four regions, along a 1300-km latitudinal gradient of Sweden. Open-top chambers were used to passively increase temperature, paired with controls. Growth and reproductive traits were measured from 320 plants (four regions × five sites × two treatments × eight plants) over two consecutive seasons to assess the effect of warming over time. We found that warming increased plant height, leaf area, number of leaves, and roots. High-latitude populations responded more strongly to warming than low-latitude populations, especially by increasing leaf area. Warming increased number of flowers in general, but only in the second year, while number of fruits increased in low-latitude populations the first year. Prolonged warming leads to an increase in both number of leaves and flowers over time. While reproduction shows varying and regional responses to warming, impacts on plant growth, especially in high-latitude populations, have more profound effects. Such effects could lead to changes in plant community composition with increased abundance of fast-growing plants with larger leaves and more clones, affecting plant competition and ecological functions such as decomposition and nutrient retention. Effects of warming were highly context dependent; thus, we encourage further use of warming experiments to predict changes in growth, reproduction, and community composition across wetland types and climate gradients targeting different plant forms.},\n\tlanguage = {en},\n\tnumber = {22},\n\turldate = {2022-01-20},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Lindborg, Regina and Ermold, Matti and Kuglerová, Lenka and Jansson, Roland and Larson, Keith W. and Milbau, Ann and Cousins, Sara A. O.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.8303},\n\tkeywords = {\\#nosource, Caltha palustris, climate change, experiment, open top chamber, traits, wetland},\n\tpages = {16228--16238},\n}\n\n\n\n\n\n Global warming affects plant fitness through changes in functional traits and thereby ecosystem function. Wetlands are declining worldwide, and hence, ecosystem functions linked to wetlands are threatened. We use Caltha palustris “a common wetland plant” to study whether warming affects growth and reproduction differently depending on origin of source population, potentially affecting phenotypic response to local climate. We conducted a 2-year in situ temperature manipulation experiment using clone pairs of C. palustris in four regions, along a 1300-km latitudinal gradient of Sweden. Open-top chambers were used to passively increase temperature, paired with controls. Growth and reproductive traits were measured from 320 plants (four regions × five sites × two treatments × eight plants) over two consecutive seasons to assess the effect of warming over time. We found that warming increased plant height, leaf area, number of leaves, and roots. High-latitude populations responded more strongly to warming than low-latitude populations, especially by increasing leaf area. Warming increased number of flowers in general, but only in the second year, while number of fruits increased in low-latitude populations the first year. Prolonged warming leads to an increase in both number of leaves and flowers over time. While reproduction shows varying and regional responses to warming, impacts on plant growth, especially in high-latitude populations, have more profound effects. Such effects could lead to changes in plant community composition with increased abundance of fast-growing plants with larger leaves and more clones, affecting plant competition and ecological functions such as decomposition and nutrient retention. Effects of warming were highly context dependent; thus, we encourage further use of warming experiments to predict changes in growth, reproduction, and community composition across wetland types and climate gradients targeting different plant forms.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer.\n \n \n \n \n\n\n \n Donis, D.; Mantzouki, E.; McGinnis, D. F.; Vachon, D.; Gallego, I.; Grossart, H.; de Senerpont Domis, L. N.; Teurlincx, S.; Seelen, L.; Lürling, M.; Verstijnen, Y.; Maliaka, V.; Fonvielle, J.; Visser, P. M.; Verspagen, J.; van Herk, M.; Antoniou, M. G.; Tsiarta, N.; McCarthy, V.; Perello, V. C.; Machado-Vieira, D.; de Oliveira, A. G.; Maronić, D. Š.; Stević, F.; Pfeiffer, T. Ž.; Vucelić, I. B.; Žutinić, P.; Udovič, M. G.; Plenković-Moraj, A.; Bláha, L.; Geriš, R.; Fránková, M.; Christoffersen, K. S.; Warming, T. P.; Feldmann, T.; Laas, A.; Panksep, K.; Tuvikene, L.; Kangro, K.; Koreivienė, J.; Karosienė, J.; Kasperovičienė, J.; Savadova-Ratkus, K.; Vitonytė, I.; Häggqvist, K.; Salmi, P.; Arvola, L.; Rothhaupt, K.; Avagianos, C.; Kaloudis, T.; Gkelis, S.; Panou, M.; Triantis, T.; Zervou, S.; Hiskia, A.; Obertegger, U.; Boscaini, A.; Flaim, G.; Salmaso, N.; Cerasino, L.; Haande, S.; Skjelbred, B.; Grabowska, M.; Karpowicz, M.; Chmura, D.; Nawrocka, L.; Kobos, J.; Mazur-Marzec, H.; Alcaraz-Párraga, P.; Wilk-Woźniak, E.; Krztoń, W.; Walusiak, E.; Gagala-Borowska, I.; Mankiewicz-Boczek, J.; Toporowska, M.; Pawlik-Skowronska, B.; Niedźwiecki, M.; Pęczuła, W.; Napiórkowska-Krzebietke, A.; Dunalska, J.; Sieńska, J.; Szymański, D.; Kruk, M.; Budzyńska, A.; Goldyn, R.; Kozak, A.; Rosińska, J.; Szeląg-Wasielewska, E.; Domek, P.; Jakubowska-Krepska, N.; Kwasizur, K.; Messyasz, B.; Pełechata, A.; Pełechaty, M.; Kokocinski, M.; Madrecka-Witkowska, B.; Kostrzewska-Szlakowska, I.; Frąk, M.; Bańkowska-Sobczak, A.; Wasilewicz, M.; Ochocka, A.; Pasztaleniec, A.; Jasser, I.; Antão-Geraldes, A. M.; Leira, M.; Vasconcelos, V.; Morais, J.; Vale, M.; Raposeiro, P. M.; Gonçalves, V.; Aleksovski, B.; Krstić, S.; Nemova, H.; Drastichova, I.; Chomova, L.; Remec-Rekar, S.; Elersek, T.; Hansson, L.; Urrutia-Cordero, P.; Bravo, A. G.; Buck, M.; Colom-Montero, W.; Mustonen, K.; Pierson, D.; Yang, Y.; Richardson, J.; Edwards, C.; Cromie, H.; Delgado-Martín, J.; García, D.; Cereijo, J. L.; Gomà, J.; Trapote, M. C.; Vegas-Vilarrúbia, T.; Obrador, B.; García-Murcia, A.; Real, M.; Romans, E.; Noguero-Ribes, J.; Duque, D. P.; Fernández-Morán, E.; Úbeda, B.; Gálvez, J. Á.; Catalán, N.; Pérez-Martínez, C.; Ramos-Rodríguez, E.; Cillero-Castro, C.; Moreno-Ostos, E.; Blanco, J. M.; Rodríguez, V.; Montes-Pérez, J. J.; Palomino, R. L.; Rodríguez-Pérez, E.; Hernández, A.; Carballeira, R.; Camacho, A.; Picazo, A.; Rochera, C.; Santamans, A. C.; Ferriol, C.; Romo, S.; Soria, J. M.; Özen, A.; Karan, T.; Demir, N.; Beklioğlu, M.; Filiz, N.; Levi, E.; Iskin, U.; Bezirci, G.; Tavşanoğlu, Ü. N.; Çelik, K.; Ozhan, K.; Karakaya, N.; Koçer, M. A. T.; Yilmaz, M.; Maraşlıoğlu, F.; Fakioglu, Ö.; Soylu, E. N.; Yağcı, M. A.; Çınar, Ş.; Çapkın, K.; Yağcı, A.; Cesur, M.; Bilgin, F.; Bulut, C.; Uysal, R.; Latife, K.; Akçaalan, R.; Albay, M.; Alp, M. T.; Özkan, K.; Sevindik, T. O.; Tunca, H.; Önem, B.; Paerl, H.; Carey, C. C.; and Ibelings, B. W.\n\n\n \n\n\n\n Limnology and Oceanography, 66(12): 4314–4333. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11963\n\n\n\n
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\n\n\n@article{donis_stratification_2021,\n\ttitle = {Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a {European} multilake survey in a heatwave summer},\n\tvolume = {66},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11963},\n\tdoi = {10.1002/lno.11963},\n\tabstract = {To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2022-01-20},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Donis, Daphne and Mantzouki, Evanthia and McGinnis, Daniel F. and Vachon, Dominic and Gallego, Irene and Grossart, Hans-Peter and de Senerpont Domis, Lisette N. and Teurlincx, Sven and Seelen, Laura and Lürling, Miquel and Verstijnen, Yvon and Maliaka, Valentini and Fonvielle, Jeremy and Visser, Petra M. and Verspagen, Jolanda and van Herk, Maria and Antoniou, Maria G. and Tsiarta, Nikoletta and McCarthy, Valerie and Perello, Victor C. and Machado-Vieira, Danielle and de Oliveira, Alinne Gurjão and Maronić, Dubravka Špoljarić and Stević, Filip and Pfeiffer, Tanja Žuna and Vucelić, Itana Bokan and Žutinić, Petar and Udovič, Marija Gligora and Plenković-Moraj, Anđelka and Bláha, Luděk and Geriš, Rodan and Fránková, Markéta and Christoffersen, Kirsten Seestern and Warming, Trine Perlt and Feldmann, Tõnu and Laas, Alo and Panksep, Kristel and Tuvikene, Lea and Kangro, Kersti and Koreivienė, Judita and Karosienė, Jūratė and Kasperovičienė, Jūratė and Savadova-Ratkus, Ksenija and Vitonytė, Irma and Häggqvist, Kerstin and Salmi, Pauliina and Arvola, Lauri and Rothhaupt, Karl and Avagianos, Christos and Kaloudis, Triantafyllos and Gkelis, Spyros and Panou, Manthos and Triantis, Theodoros and Zervou, Sevasti-Kiriaki and Hiskia, Anastasia and Obertegger, Ulrike and Boscaini, Adriano and Flaim, Giovanna and Salmaso, Nico and Cerasino, Leonardo and Haande, Sigrid and Skjelbred, Birger and Grabowska, Magdalena and Karpowicz, Maciej and Chmura, Damian and Nawrocka, Lidia and Kobos, Justyna and Mazur-Marzec, Hanna and Alcaraz-Párraga, Pablo and Wilk-Woźniak, Elżbieta and Krztoń, Wojciech and Walusiak, Edward and Gagala-Borowska, Ilona and Mankiewicz-Boczek, Joana and Toporowska, Magdalena and Pawlik-Skowronska, Barbara and Niedźwiecki, Michał and Pęczuła, Wojciech and Napiórkowska-Krzebietke, Agnieszka and Dunalska, Julita and Sieńska, Justyna and Szymański, Daniel and Kruk, Marek and Budzyńska, Agnieszka and Goldyn, Ryszard and Kozak, Anna and Rosińska, Joanna and Szeląg-Wasielewska, Elżbieta and Domek, Piotr and Jakubowska-Krepska, Natalia and Kwasizur, Kinga and Messyasz, Beata and Pełechata, Aleksandra and Pełechaty, Mariusz and Kokocinski, Mikolaj and Madrecka-Witkowska, Beata and Kostrzewska-Szlakowska, Iwona and Frąk, Magdalena and Bańkowska-Sobczak, Agnieszka and Wasilewicz, Michał and Ochocka, Agnieszka and Pasztaleniec, Agnieszka and Jasser, Iwona and Antão-Geraldes, Ana M. and Leira, Manel and Vasconcelos, Vitor and Morais, Joao and Vale, Micaela and Raposeiro, Pedro M. and Gonçalves, Vítor and Aleksovski, Boris and Krstić, Svetislav and Nemova, Hana and Drastichova, Iveta and Chomova, Lucia and Remec-Rekar, Spela and Elersek, Tina and Hansson, Lars-Anders and Urrutia-Cordero, Pablo and Bravo, Andrea G. and Buck, Moritz and Colom-Montero, William and Mustonen, Kristiina and Pierson, Don and Yang, Yang and Richardson, Jessica and Edwards, Christine and Cromie, Hannah and Delgado-Martín, Jordi and García, David and Cereijo, Jose Luís and Gomà, Joan and Trapote, Mari Carmen and Vegas-Vilarrúbia, Teresa and Obrador, Biel and García-Murcia, Ana and Real, Monserrat and Romans, Elvira and Noguero-Ribes, Jordi and Duque, David Parreño and Fernández-Morán, Elísabeth and Úbeda, Bárbara and Gálvez, José Ángel and Catalán, Núria and Pérez-Martínez, Carmen and Ramos-Rodríguez, Eloísa and Cillero-Castro, Carmen and Moreno-Ostos, Enrique and Blanco, José María and Rodríguez, Valeriano and Montes-Pérez, Jorge Juan and Palomino, Roberto L. and Rodríguez-Pérez, Estela and Hernández, Armand and Carballeira, Rafael and Camacho, Antonio and Picazo, Antonio and Rochera, Carlos and Santamans, Anna C. and Ferriol, Carmen and Romo, Susana and Soria, Juan Miguel and Özen, Arda and Karan, Tünay and Demir, Nilsun and Beklioğlu, Meryem and Filiz, Nur and Levi, Eti and Iskin, Uğur and Bezirci, Gizem and Tavşanoğlu, Ülkü Nihan and Çelik, Kemal and Ozhan, Koray and Karakaya, Nusret and Koçer, Mehmet Ali Turan and Yilmaz, Mete and Maraşlıoğlu, Faruk and Fakioglu, Özden and Soylu, Elif Neyran and Yağcı, Meral Apaydın and Çınar, Şakir and Çapkın, Kadir and Yağcı, Abdulkadir and Cesur, Mehmet and Bilgin, Fuat and Bulut, Cafer and Uysal, Rahmi and Latife, Köker and Akçaalan, Reyhan and Albay, Meriç and Alp, Mehmet Tahir and Özkan, Korhan and Sevindik, Tuğba Ongun and Tunca, Hatice and Önem, Burçin and Paerl, Hans and Carey, Cayelan C. and Ibelings, Bastiaan W.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11963},\n\tkeywords = {\\#nosource},\n\tpages = {4314--4333},\n}\n\n\n\n\n\n To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon dioxide fluxes increase from day to night across European streams.\n \n \n \n \n\n\n \n Attermeyer, K.; Casas-Ruiz, J. P.; Fuss, T.; Pastor, A.; Cauvy-Fraunié, S.; Sheath, D.; Nydahl, A. C.; Doretto, A.; Portela, A. P.; Doyle, B. C.; Simov, N.; Gutmann Roberts, C.; Niedrist, G. H.; Timoner, X.; Evtimova, V.; Barral-Fraga, L.; Bašić, T.; Audet, J.; Deininger, A.; Busst, G.; Fenoglio, S.; Catalán, N.; de Eyto, E.; Pilotto, F.; Mor, J.; Monteiro, J.; Fletcher, D.; Noss, C.; Colls, M.; Nagler, M.; Liu, L.; Romero González-Quijano, C.; Romero, F.; Pansch, N.; Ledesma, J. L. J.; Pegg, J.; Klaus, M.; Freixa, A.; Herrero Ortega, S.; Mendoza-Lera, C.; Bednařík, A.; Fonvielle, J. A.; Gilbert, P. J.; Kenderov, L. A.; Rulík, M.; and Bodmer, P.\n\n\n \n\n\n\n Communications Earth & Environment, 2(1): 118. December 2021.\n \n\n\n\n
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\n\n\n@article{attermeyer_carbon_2021,\n\ttitle = {Carbon dioxide fluxes increase from day to night across {European} streams},\n\tvolume = {2},\n\tissn = {2662-4435},\n\turl = {http://www.nature.com/articles/s43247-021-00192-w},\n\tdoi = {10.1038/s43247-021-00192-w},\n\tabstract = {Abstract\n \n Globally, inland waters emit over 2 Pg of carbon per year as carbon dioxide, of which the majority originates from streams and rivers. Despite the global significance of fluvial carbon dioxide emissions, little is known about their diel dynamics. Here we present a large-scale assessment of day- and night-time carbon dioxide fluxes at the water-air interface across 34 European streams. We directly measured fluxes four times between October 2016 and July 2017 using drifting chambers. Median fluxes are 1.4 and 2.1 mmol m\n −2\n h\n −1\n at midday and midnight, respectively, with night fluxes exceeding those during the day by 39\\%. We attribute diel carbon dioxide flux variability mainly to changes in the water partial pressure of carbon dioxide. However, no consistent drivers could be identified across sites. Our findings highlight widespread day-night changes in fluvial carbon dioxide fluxes and suggest that the time of day greatly influences measured carbon dioxide fluxes across European streams.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2021-09-03},\n\tjournal = {Communications Earth \\& Environment},\n\tauthor = {Attermeyer, Katrin and Casas-Ruiz, Joan Pere and Fuss, Thomas and Pastor, Ada and Cauvy-Fraunié, Sophie and Sheath, Danny and Nydahl, Anna C. and Doretto, Alberto and Portela, Ana Paula and Doyle, Brian C. and Simov, Nikolay and Gutmann Roberts, Catherine and Niedrist, Georg H. and Timoner, Xisca and Evtimova, Vesela and Barral-Fraga, Laura and Bašić, Tea and Audet, Joachim and Deininger, Anne and Busst, Georgina and Fenoglio, Stefano and Catalán, Núria and de Eyto, Elvira and Pilotto, Francesca and Mor, Jordi-René and Monteiro, Juliana and Fletcher, David and Noss, Christian and Colls, Miriam and Nagler, Magdalena and Liu, Liu and Romero González-Quijano, Clara and Romero, Ferran and Pansch, Nina and Ledesma, José L. J. and Pegg, Josephine and Klaus, Marcus and Freixa, Anna and Herrero Ortega, Sonia and Mendoza-Lera, Clara and Bednařík, Adam and Fonvielle, Jérémy A. and Gilbert, Peter J. and Kenderov, Lyubomir A. and Rulík, Martin and Bodmer, Pascal},\n\tmonth = dec,\n\tyear = {2021},\n\tkeywords = {\\#nosource},\n\tpages = {118},\n}\n\n\n\n\n\n Abstract Globally, inland waters emit over 2 Pg of carbon per year as carbon dioxide, of which the majority originates from streams and rivers. Despite the global significance of fluvial carbon dioxide emissions, little is known about their diel dynamics. Here we present a large-scale assessment of day- and night-time carbon dioxide fluxes at the water-air interface across 34 European streams. We directly measured fluxes four times between October 2016 and July 2017 using drifting chambers. Median fluxes are 1.4 and 2.1 mmol m −2 h −1 at midday and midnight, respectively, with night fluxes exceeding those during the day by 39%. We attribute diel carbon dioxide flux variability mainly to changes in the water partial pressure of carbon dioxide. However, no consistent drivers could be identified across sites. Our findings highlight widespread day-night changes in fluvial carbon dioxide fluxes and suggest that the time of day greatly influences measured carbon dioxide fluxes across European streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Moving towards multi-layered, mixed-species forests in riparian buffers will enhance their long-term function in boreal landscapes.\n \n \n \n \n\n\n \n Maher Hasselquist, E.; Kuglerová, L.; Sjögren, J.; Hjältén, J.; Ring, E.; Sponseller, R. A.; Andersson, E.; Lundström, J.; Mancheva, I.; Nordin, A.; and Laudon, H.\n\n\n \n\n\n\n Forest Ecology and Management, 493: 119254. August 2021.\n \n\n\n\n
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\n\n\n@article{maher_hasselquist_moving_2021,\n\ttitle = {Moving towards multi-layered, mixed-species forests in riparian buffers will enhance their long-term function in boreal landscapes},\n\tvolume = {493},\n\tissn = {03781127},\n\turl = {https://linkinghub.elsevier.com/retrieve/pii/S037811272100342X},\n\tdoi = {10.1016/j.foreco.2021.119254},\n\tabstract = {Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream’s edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage.},\n\tlanguage = {en},\n\turldate = {2021-09-03},\n\tjournal = {Forest Ecology and Management},\n\tauthor = {Maher Hasselquist, Eliza and Kuglerová, Lenka and Sjögren, Jörgen and Hjältén, Joakim and Ring, Eva and Sponseller, Ryan A. and Andersson, Elisabet and Lundström, Johanna and Mancheva, Irina and Nordin, Annika and Laudon, Hjalmar},\n\tmonth = aug,\n\tyear = {2021},\n\tkeywords = {\\#nosource},\n\tpages = {119254},\n}\n\n\n\n\n\n Riparian buffers are the primary tool in forest management for protecting the habitat structure and function of streams. They help protect against biogeochemical perturbation, filter sediments and nutrients, prevent erosion, contribute food to aquatic organisms, regulate light and hence water temperature, contribute deadwood, and preserve biodiversity. However, in production forests of Sweden and Finland, many headwater streams have been straightened, ditched, and/or channelized, resulting in altered hydrology and reduced natural disturbance by floods, which in turn affects important riparian functions. Furthermore, in even-aged management systems as practiced in much of Fennoscandia, understory trees have usually been cleared right up to the stream’s edge during thinning operations, especially around small, headwater streams. Fire suppression has further favored succession towards shade tolerant species. In the regions within Fennoscandia that have experienced this combination of intensive management and lack of natural disturbance, riparian zones are now dominated by single-storied, native Norway spruce. When the adjacent forest is cut, thin (5 - 15m) conifer-dominated riparian buffers are typically left. These buffers do not provide the protection and subsidies, in terms of leaf litter quality, needed to maintain water quality or support riparian or aquatic biodiversity. Based on a literature review, we found compelling evidence that the ecological benefits of multi-layered, mixed-species riparian forest with a large component of broadleaved species are higher than what is now commonly found in the managed stands of Fennoscandia. To improve the functionality of riparian zones, and hence the protection of streams in managed forest landscapes, we present some basic principles that could be used to enhance the ecological function of these interfaces. These management actions should be prioritized on streams and streamside stands that have been affected by simplification either through forest management or hydrological modification. Key to these principles is the planning and managing of buffer zones as early as possible in the rotation to ensure improved function throughout the rotation cycle and not only at final felling. This is well in line with EU and national legislation which can be interpreted as requiring landscape planning at all forest ages to meet biodiversity and other environmental goals. However, it is still rare that planning for conservation is done other than at the final felling stage. Implementing this new strategy is likely to have long-term positive effects and improve the protection of surface waters from negative forestry effects and a history of fire suppression. By following these suggested management principles, there will be a longer time period with high function and greater future management flexibility in addition to the benefits provided by leaving riparian buffers at the final felling stage.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Role of Macroinvertebrates on Plant Litter Decomposition in Streams.\n \n \n \n \n\n\n \n Jonsson, M.; and Sponseller, R. A.\n\n\n \n\n\n\n In Swan, C. M.; Boyero, L.; and Canhoto, C., editor(s), The Ecology of Plant Litter Decomposition in Stream Ecosystems, pages 193–216. Springer International Publishing, Cham, 2021.\n \n\n\n\n
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\n\n\n@incollection{jonsson_role_2021,\n\taddress = {Cham},\n\ttitle = {The {Role} of {Macroinvertebrates} on {Plant} {Litter} {Decomposition} in {Streams}},\n\tisbn = {978-3-030-72854-0},\n\turl = {https://doi.org/10.1007/978-3-030-72854-0_10},\n\tabstract = {Macroinvertebrate detritivores (i.e., shredders) in freshwaters are often a main driver of decomposition rates of terrestrial plant litter. Yet, the extent to which shredders drive this process depends on the specific functional traits and species present in the shredder community, which in turn are determined by the broader species pool, as well as a range of local environmental conditions, such as pH, substrate characteristics, water chemistry, water temperature, and current velocity. Projected global change will modify several of these environmental conditions, with potential consequences for litter decomposition rates and overall carbon cycling in freshwaters. In this chapter, we describe how a range of freshwater environmental conditions determines the presence of certain species (i.e., functional traits) and the characteristics of shredder communities (i.e., species composition and richness). We then discuss how these characteristics in turn may influence interactions among shredders, and between shredders and other freshwater organisms, to determine their influence on litter decomposition in streams.},\n\tlanguage = {en},\n\turldate = {2021-09-03},\n\tbooktitle = {The {Ecology} of {Plant} {Litter} {Decomposition} in {Stream} {Ecosystems}},\n\tpublisher = {Springer International Publishing},\n\tauthor = {Jonsson, Micael and Sponseller, Ryan A.},\n\teditor = {Swan, Christopher M. and Boyero, Luz and Canhoto, Cristina},\n\tyear = {2021},\n\tdoi = {10.1007/978-3-030-72854-0_10},\n\tkeywords = {\\#nosource},\n\tpages = {193--216},\n}\n\n\n\n\n\n Macroinvertebrate detritivores (i.e., shredders) in freshwaters are often a main driver of decomposition rates of terrestrial plant litter. Yet, the extent to which shredders drive this process depends on the specific functional traits and species present in the shredder community, which in turn are determined by the broader species pool, as well as a range of local environmental conditions, such as pH, substrate characteristics, water chemistry, water temperature, and current velocity. Projected global change will modify several of these environmental conditions, with potential consequences for litter decomposition rates and overall carbon cycling in freshwaters. In this chapter, we describe how a range of freshwater environmental conditions determines the presence of certain species (i.e., functional traits) and the characteristics of shredder communities (i.e., species composition and richness). We then discuss how these characteristics in turn may influence interactions among shredders, and between shredders and other freshwater organisms, to determine their influence on litter decomposition in streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions.\n \n \n \n \n\n\n \n Gómez-Gener, L.; Rocher-Ros, G.; Battin, T.; Cohen, M. J.; Dalmagro, H. J.; Dinsmore, K. J.; Drake, T. W.; Duvert, C.; Enrich-Prast, A.; Horgby, Å.; Johnson, M. S.; Kirk, L.; Machado-Silva, F.; Marzolf, N. S.; McDowell, M. J.; McDowell, W. H.; Miettinen, H.; Ojala, A. K.; Peter, H.; Pumpanen, J.; Ran, L.; Riveros-Iregui, D. A.; Santos, I. R.; Six, J.; Stanley, E. H.; Wallin, M. B.; White, S. A.; and Sponseller, R. A.\n\n\n \n\n\n\n Nature Geoscience, 14(5): 289–294. May 2021.\n Bandiera_abtest: a Cg_type: Nature Research Journals Number: 5 Primary_atype: Research Publisher: Nature Publishing Group Subject_term: Carbon cycle;Ecosystem ecology;Limnology Subject_term_id: carbon-cycle;ecosystem-ecology;limnology\n\n\n\n
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\n\n\n@article{gomez-gener_global_2021,\n\ttitle = {Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions},\n\tvolume = {14},\n\tcopyright = {2021 The Author(s), under exclusive licence to Springer Nature Limited},\n\tissn = {1752-0908},\n\turl = {https://www.nature.com/articles/s41561-021-00722-3},\n\tdoi = {10.1038/s41561-021-00722-3},\n\tabstract = {Carbon dioxide (CO2) emissions to the atmosphere from running waters are estimated to be four times greater than the total carbon (C) flux to the oceans. However, these fluxes remain poorly constrained because of substantial spatial and temporal variability in dissolved CO2 concentrations. Using a global compilation of high-frequency CO2 measurements, we demonstrate that nocturnal CO2 emissions are on average 27\\% (0.9 gC m−2 d−1) greater than those estimated from diurnal concentrations alone. Constraints on light availability due to canopy shading or water colour are the principal controls on observed diel (24 hour) variation, suggesting this nocturnal increase arises from daytime fixation of CO2 by photosynthesis. Because current global estimates of CO2 emissions to the atmosphere from running waters (0.65–1.8 PgC yr−1) rely primarily on discrete measurements of dissolved CO2 obtained during the day, they substantially underestimate the magnitude of this flux. Accounting for night-time CO2 emissions may elevate global estimates from running waters to the atmosphere by 0.20–0.55 PgC yr−1.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2021-09-03},\n\tjournal = {Nature Geoscience},\n\tauthor = {Gómez-Gener, Lluís and Rocher-Ros, Gerard and Battin, Tom and Cohen, Matthew J. and Dalmagro, Higo J. and Dinsmore, Kerry J. and Drake, Travis W. and Duvert, Clément and Enrich-Prast, Alex and Horgby, Åsa and Johnson, Mark S. and Kirk, Lily and Machado-Silva, Fausto and Marzolf, Nicholas S. and McDowell, Mollie J. and McDowell, William H. and Miettinen, Heli and Ojala, Anne K. and Peter, Hannes and Pumpanen, Jukka and Ran, Lishan and Riveros-Iregui, Diego A. and Santos, Isaac R. and Six, Johan and Stanley, Emily H. and Wallin, Marcus B. and White, Shane A. and Sponseller, Ryan A.},\n\tmonth = may,\n\tyear = {2021},\n\tnote = {Bandiera\\_abtest: a\nCg\\_type: Nature Research Journals\nNumber: 5\nPrimary\\_atype: Research\nPublisher: Nature Publishing Group\nSubject\\_term: Carbon cycle;Ecosystem ecology;Limnology\nSubject\\_term\\_id: carbon-cycle;ecosystem-ecology;limnology},\n\tkeywords = {\\#nosource},\n\tpages = {289--294},\n}\n\n\n\n\n\n Carbon dioxide (CO2) emissions to the atmosphere from running waters are estimated to be four times greater than the total carbon (C) flux to the oceans. However, these fluxes remain poorly constrained because of substantial spatial and temporal variability in dissolved CO2 concentrations. Using a global compilation of high-frequency CO2 measurements, we demonstrate that nocturnal CO2 emissions are on average 27% (0.9 gC m−2 d−1) greater than those estimated from diurnal concentrations alone. Constraints on light availability due to canopy shading or water colour are the principal controls on observed diel (24 hour) variation, suggesting this nocturnal increase arises from daytime fixation of CO2 by photosynthesis. Because current global estimates of CO2 emissions to the atmosphere from running waters (0.65–1.8 PgC yr−1) rely primarily on discrete measurements of dissolved CO2 obtained during the day, they substantially underestimate the magnitude of this flux. Accounting for night-time CO2 emissions may elevate global estimates from running waters to the atmosphere by 0.20–0.55 PgC yr−1.\n
\n\n\n\n \n\n \n \n \n \n \n \n Tree line advance reduces mixing and oxygen concentrations in arctic–alpine lakes through wind sheltering and organic carbon supply.\n \n \n \n \n\n\n \n Klaus, M.; Karlsson, J.; and Seekell, D.\n\n\n \n\n\n\n Global Change Biology, 27(18): 4238–4253. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15660\n\n\n\n
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\n\n\n@article{klaus_tree_2021,\n\ttitle = {Tree line advance reduces mixing and oxygen concentrations in arctic–alpine lakes through wind sheltering and organic carbon supply},\n\tvolume = {27},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15660},\n\tdoi = {10.1111/gcb.15660},\n\tabstract = {Oxygen depletion in lake bottom waters has adverse impacts on ecosystem health including decreased water quality from release of nutrients and reduced substances from sediments, and the reduction of fish growth and reproduction. Depletion occurs when oxygen is consumed during decomposition of organic matter, and oxygen replenishment is limited by water column stratification. Arctic–alpine lakes are often well mixed and oxygenated, but rapid climate change in these regions is an important driver of shifts in catchment vegetation that could affect the mixing and oxygen dynamics of lakes. Here, we analyze high-resolution time series of dissolved oxygen concentration and temperature profiles in 40 Swedish arctic–alpine lakes across the tree line ecotone. The lakes stratified for 1−125 days, and during stratification, near-bottom dissolved oxygen concentrations changed by −0.20 to +0.15 mg L−1 day−1, resulting in final concentrations of 1.1−15.5 mg L−1 at the end of the longest stratification period. Structural equation modeling revealed that lakes with taller shoreline vegetation relative to lake area had higher dissolved organic carbon concentrations and oxygen consumption rates, but also lower wind speeds and longer stratification periods, and ultimately, lower near-bottom dissolved oxygen concentrations. We use an index of shoreline canopy height and lake area to predict variations among our study lakes in near-bottom dissolved oxygen concentrations at the end of the longest stratification period (R2 = 0.41). Upscaling this relationship to 8392 Swedish arctic–alpine lakes revealed that near-bottom dissolved oxygen concentrations drop below 3, 5, and 7 mg L−1 in 15\\%, 32\\%, and 53\\% of the lakes and that this proportion is sensitive (5\\%−22\\%, 13\\%−45\\%, and 29\\%−69\\%) to hypothetical tree line shifts observed in the past century or reconstructed for the Holocene (±200 m elevation; ±0.5° latitude). Assuming space-for-time substitution, we predict that tree line advance will decrease near-bottom dissolved oxygen concentrations in many arctic–alpine lakes.},\n\tlanguage = {en},\n\tnumber = {18},\n\turldate = {2021-09-03},\n\tjournal = {Global Change Biology},\n\tauthor = {Klaus, Marcus and Karlsson, Jan and Seekell, David},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15660},\n\tkeywords = {\\#nosource, dissolved organic carbon, environmental change, forest–tundra ecotone, hypoxia, lake ecosystem, lake stratification, thermal structure, wind speed},\n\tpages = {4238--4253},\n}\n\n\n\n\n\n Oxygen depletion in lake bottom waters has adverse impacts on ecosystem health including decreased water quality from release of nutrients and reduced substances from sediments, and the reduction of fish growth and reproduction. Depletion occurs when oxygen is consumed during decomposition of organic matter, and oxygen replenishment is limited by water column stratification. Arctic–alpine lakes are often well mixed and oxygenated, but rapid climate change in these regions is an important driver of shifts in catchment vegetation that could affect the mixing and oxygen dynamics of lakes. Here, we analyze high-resolution time series of dissolved oxygen concentration and temperature profiles in 40 Swedish arctic–alpine lakes across the tree line ecotone. The lakes stratified for 1−125 days, and during stratification, near-bottom dissolved oxygen concentrations changed by −0.20 to +0.15 mg L−1 day−1, resulting in final concentrations of 1.1−15.5 mg L−1 at the end of the longest stratification period. Structural equation modeling revealed that lakes with taller shoreline vegetation relative to lake area had higher dissolved organic carbon concentrations and oxygen consumption rates, but also lower wind speeds and longer stratification periods, and ultimately, lower near-bottom dissolved oxygen concentrations. We use an index of shoreline canopy height and lake area to predict variations among our study lakes in near-bottom dissolved oxygen concentrations at the end of the longest stratification period (R2 = 0.41). Upscaling this relationship to 8392 Swedish arctic–alpine lakes revealed that near-bottom dissolved oxygen concentrations drop below 3, 5, and 7 mg L−1 in 15%, 32%, and 53% of the lakes and that this proportion is sensitive (5%−22%, 13%−45%, and 29%−69%) to hypothetical tree line shifts observed in the past century or reconstructed for the Holocene (±200 m elevation; ±0.5° latitude). Assuming space-for-time substitution, we predict that tree line advance will decrease near-bottom dissolved oxygen concentrations in many arctic–alpine lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Fractal Scaling Relationship for River Inlets to Lakes.\n \n \n \n \n\n\n \n Seekell, D.; Cael, B.; Lindmark, E.; and Byström, P.\n\n\n \n\n\n\n Geophysical Research Letters, 48(9): e2021GL093366. 2021.\n _eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021GL093366\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{seekell_fractal_2021,\n\ttitle = {The {Fractal} {Scaling} {Relationship} for {River} {Inlets} to {Lakes}},\n\tvolume = {48},\n\tissn = {1944-8007},\n\turl = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021GL093366},\n\tdoi = {10.1029/2021GL093366},\n\tabstract = {Scaling relationships provide simple rules for understanding complex hydrographic patterns. Globally, river inlet abundance varies among lakes by about three orders of magnitude, but few scaling relationships describe this aspect of lake-river connectivity. In this study, we describe a simple theoretical scaling relationship between lake surface area and river inlet abundance, and test this theory using data from Scandinavia. On average, the number of inlets increases by 67\\% for each doubling of lake area. However, lakes of vastly different areas can have the same number of inlets with relatively small variations of drainage density, lake shape, or junction angle - characteristics that can often be linked to specific geological processes. Our approach bridges the gap between the detailed understanding of geomorphic processes and large-scale statistical relationships, and engenders predictions about additional patterns including the relationship between lake area and water residence time.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2021-09-03},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Seekell, D. and Cael, B. and Lindmark, E. and Byström, P.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021GL093366},\n\tkeywords = {\\#nosource, fractal dimension, hydrography, junction angle, river inlets, scaling},\n\tpages = {e2021GL093366},\n}\n\n\n\n\n\n Scaling relationships provide simple rules for understanding complex hydrographic patterns. Globally, river inlet abundance varies among lakes by about three orders of magnitude, but few scaling relationships describe this aspect of lake-river connectivity. In this study, we describe a simple theoretical scaling relationship between lake surface area and river inlet abundance, and test this theory using data from Scandinavia. On average, the number of inlets increases by 67% for each doubling of lake area. However, lakes of vastly different areas can have the same number of inlets with relatively small variations of drainage density, lake shape, or junction angle - characteristics that can often be linked to specific geological processes. Our approach bridges the gap between the detailed understanding of geomorphic processes and large-scale statistical relationships, and engenders predictions about additional patterns including the relationship between lake area and water residence time.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Role of Methane Transport From the Active Layer in Sustaining Methane Emissions and Food Chains in Subarctic Ponds.\n \n \n \n \n\n\n \n Olid, C.; Zannella, A.; and Lau, D. C. P.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 126(3): e2020JG005810. 2021.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005810\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{olid_role_2021,\n\ttitle = {The {Role} of {Methane} {Transport} {From} the {Active} {Layer} in {Sustaining} {Methane} {Emissions} and {Food} {Chains} in {Subarctic} {Ponds}},\n\tvolume = {126},\n\tcopyright = {© 2021. The Authors.},\n\tissn = {2169-8961},\n\turl = {http://agupubs.pericles.prod.literatumonline.com/doi/abs/10.1029/2020JG005810},\n\tdoi = {10.1029/2020jg005810},\n\tabstract = {Groundwater discharge from the seasonally thawed active layer is increasingly recognized as an important pathway for delivering methane (CH4) into Arctic lakes and streams, but its contribution to CH4 emissions from thaw ponds and its influence on the trophic support and nutritional quality of pond food chains remains unexplored. We quantified the transport of CH4 from the active layer through groundwater discharge into thaw ponds in a subarctic catchment in northern Sweden, using radon (222Rn) as groundwater tracer. We analyzed stable isotopes and fatty acids of pond macroinvertebrates to evaluate the potential effects of groundwater-mediated CH4 inputs on the aquatic food chains. Our results indicate that active layer groundwater discharge flows are nontrivial (range 6\\%–46\\% of pond volume per day) and the associated CH4 fluxes (median 339 mg C m−2day−1, interquartile range [IQR]: 179–419 mg C m−2 day−1) can sustain the diffusive CH4 emissions from most of the ponds (155 mg C m−2 day−1, IQR: 55–234 mg C m−2 day−1). Consumers in ponds receiving greater CH4 inputs from the active layer had lower stable carbon (C) isotope signatures that indicates a greater trophic reliance on methane oxidizing bacteria (MOB), and they had lower nutritional quality as indicated by their lower tissue concentrations of polyunsaturated fatty acids. Overall, this work links physical (CH4 transport from the active layer), biogeochemical (CH4 emission), and ecological (MOB-consumer interaction) processes to provide direct evidence for the role of active layer groundwater discharge in CH4 cycling of subarctic thaw ponds.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2021-04-01},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Olid, C. and Zannella, A. and Lau, D. C. P.},\n\tyear = {2021},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005810},\n\tkeywords = {\\#nosource, climate change, groundwater, methane, methane-oxidizing bacteria, ponds, trophic chain},\n\tpages = {e2020JG005810},\n}\n\n\n\n\n\n Groundwater discharge from the seasonally thawed active layer is increasingly recognized as an important pathway for delivering methane (CH4) into Arctic lakes and streams, but its contribution to CH4 emissions from thaw ponds and its influence on the trophic support and nutritional quality of pond food chains remains unexplored. We quantified the transport of CH4 from the active layer through groundwater discharge into thaw ponds in a subarctic catchment in northern Sweden, using radon (222Rn) as groundwater tracer. We analyzed stable isotopes and fatty acids of pond macroinvertebrates to evaluate the potential effects of groundwater-mediated CH4 inputs on the aquatic food chains. Our results indicate that active layer groundwater discharge flows are nontrivial (range 6%–46% of pond volume per day) and the associated CH4 fluxes (median 339 mg C m−2day−1, interquartile range [IQR]: 179–419 mg C m−2 day−1) can sustain the diffusive CH4 emissions from most of the ponds (155 mg C m−2 day−1, IQR: 55–234 mg C m−2 day−1). Consumers in ponds receiving greater CH4 inputs from the active layer had lower stable carbon (C) isotope signatures that indicates a greater trophic reliance on methane oxidizing bacteria (MOB), and they had lower nutritional quality as indicated by their lower tissue concentrations of polyunsaturated fatty acids. Overall, this work links physical (CH4 transport from the active layer), biogeochemical (CH4 emission), and ecological (MOB-consumer interaction) processes to provide direct evidence for the role of active layer groundwater discharge in CH4 cycling of subarctic thaw ponds.\n
\n\n\n\n \n\n \n \n \n \n \n \n Idiosyncratic responses to simulated herbivory by root fungal symbionts in a subarctic meadow.\n \n \n \n \n\n\n \n Kytöviita, M.; and Olofsson, J.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 53(1): 80–92. January 2021.\n \n\n\n\n
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\n\n\n@article{kytoviita_idiosyncratic_2021,\n\ttitle = {Idiosyncratic responses to simulated herbivory by root fungal symbionts in a subarctic meadow},\n\tvolume = {53},\n\tissn = {1523-0430, 1938-4246},\n\turl = {https://www.tandfonline.com/doi/full/10.1080/15230430.2021.1878738},\n\tdoi = {10.1080/15230430.2021.1878738},\n\tabstract = {Plant-associated fungi have elementary roles in ecosystem productivity. There is little information on the interactions between arbuscular mycorrhizal (AM) fungal symbiosis, fine endophytic (FE) and dark septate endophytic (DSE) fungi, and their host plants in cold climate systems. In particular, the environmental filters potentially driving the relative abundance of these root symbionts remain unknown. We investigated the interlinkage of plant and belowground fungal responses to simu lated herbivory (clipping, fertilization, and trampling) in a subarctic meadow system. AM and FE frequency in the two target plant roots, Potentilla crantzii and Saussurea alpina, was unaffected by simulated herbivory, highlighting the importance and resilience of arbuscule forming mycorrhizas in a range of environmental conditions. Fertilization and trampling increased DSE colonization in P. crantzii roots although generally P. crantzii performance was reduced in these plots. The idiosyncratic responses by DSE fungal frequency in the two host plants in our experiment indicate that the host plant identity has a pivotal role in the DSE fungus–plant outcome. DSE fungal frequency did not respond to environmental manipulations in a manner similar to arbuscular mycorrhizas, suggesting that they have a different role in plant ecology.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2021-04-01},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Kytöviita, Minna-Maarit and Olofsson, Johan},\n\tmonth = jan,\n\tyear = {2021},\n\tkeywords = {\\#nosource},\n\tpages = {80--92},\n}\n\n\n\n\n\n Plant-associated fungi have elementary roles in ecosystem productivity. There is little information on the interactions between arbuscular mycorrhizal (AM) fungal symbiosis, fine endophytic (FE) and dark septate endophytic (DSE) fungi, and their host plants in cold climate systems. In particular, the environmental filters potentially driving the relative abundance of these root symbionts remain unknown. We investigated the interlinkage of plant and belowground fungal responses to simu lated herbivory (clipping, fertilization, and trampling) in a subarctic meadow system. AM and FE frequency in the two target plant roots, Potentilla crantzii and Saussurea alpina, was unaffected by simulated herbivory, highlighting the importance and resilience of arbuscule forming mycorrhizas in a range of environmental conditions. Fertilization and trampling increased DSE colonization in P. crantzii roots although generally P. crantzii performance was reduced in these plots. The idiosyncratic responses by DSE fungal frequency in the two host plants in our experiment indicate that the host plant identity has a pivotal role in the DSE fungus–plant outcome. DSE fungal frequency did not respond to environmental manipulations in a manner similar to arbuscular mycorrhizas, suggesting that they have a different role in plant ecology.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon emission from Western Siberian inland waters.\n \n \n \n \n\n\n \n Karlsson, J.; Serikova, S.; Vorobyev, S. N.; Rocher-Ros, G.; Denfeld, B.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Nature Communications, 12(1): 825. February 2021.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{karlsson_carbon_2021,\n\ttitle = {Carbon emission from {Western} {Siberian} inland waters},\n\tvolume = {12},\n\tcopyright = {2021 The Author(s)},\n\tissn = {2041-1723},\n\turl = {http://www.nature.com/articles/s41467-021-21054-1},\n\tdoi = {10.1038/s41467-021-21054-1},\n\tabstract = {High-latitude regions play a key role in the carbon (C) cycle and climate system. An important question is the degree of mobilization and atmospheric release of vast soil C stocks, partly stored in permafrost, with amplified warming of these regions. A fraction of this C is exported to inland waters and emitted to the atmosphere, yet these losses are poorly constrained and seldom accounted for in assessments of high-latitude C balances. This is particularly relevant for Western Siberia, with its extensive peatland C stocks, which can be strongly sensitive to the ongoing changes in climate. Here we quantify C emission from inland waters, including the Ob’ River (Arctic’s largest watershed), across all permafrost zones of Western Siberia. We show that the inland water C emission is high (0.08–0.10 Pg C yr−1) and of major significance in the regional C cycle, largely exceeding (7–9 times) C export to the Arctic Ocean and reaching nearly half (35–50\\%) of the region’s land C uptake. This important role of C emission from inland waters highlights the need for coupled land–water studies to understand the contemporary C cycle and its response to warming.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2021-04-01},\n\tjournal = {Nature Communications},\n\tauthor = {Karlsson, Jan and Serikova, Svetlana and Vorobyev, Sergey N. and Rocher-Ros, Gerard and Denfeld, Blaize and Pokrovsky, Oleg S.},\n\tmonth = feb,\n\tyear = {2021},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {825},\n}\n\n\n\n\n\n High-latitude regions play a key role in the carbon (C) cycle and climate system. An important question is the degree of mobilization and atmospheric release of vast soil C stocks, partly stored in permafrost, with amplified warming of these regions. A fraction of this C is exported to inland waters and emitted to the atmosphere, yet these losses are poorly constrained and seldom accounted for in assessments of high-latitude C balances. This is particularly relevant for Western Siberia, with its extensive peatland C stocks, which can be strongly sensitive to the ongoing changes in climate. Here we quantify C emission from inland waters, including the Ob’ River (Arctic’s largest watershed), across all permafrost zones of Western Siberia. We show that the inland water C emission is high (0.08–0.10 Pg C yr−1) and of major significance in the regional C cycle, largely exceeding (7–9 times) C export to the Arctic Ocean and reaching nearly half (35–50%) of the region’s land C uptake. This important role of C emission from inland waters highlights the need for coupled land–water studies to understand the contemporary C cycle and its response to warming.\n
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\n \n \n\n \n \n \n \n \n \n Diurnal cycles in thermokarst lakes of a permafrost peatland.\n \n \n \n \n\n\n \n Shirokova, L. S.; Payandi-Rolland, D.; Lim, A. G.; Manasypov, R. M.; Allen, J.; Rols, J.; Benezeth, P.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Limnology and Freshwater Biology, 4: 886–887. September 2020.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{shirokova_diurnal_2020,\n\ttitle = {Diurnal cycles in thermokarst lakes of a permafrost peatland},\n\tvolume = {4},\n\tcopyright = {Copyright (c) 2020 Limnology and Freshwater Biology},\n\tissn = {2658-3518},\n\turl = {http://limnolfwbiol.com/index.php/LFWB/article/view/643},\n\tdoi = {10.31951/2658-3518-2020-A-4-886},\n\tabstract = {Despite the importance of surface waters of permafrost landscapes in carbon (C) emission, dissolved C, metal storage and export, the diel pattern of dissolved components and gases in thermokarst lakes remain virtually unknown. Here we discovered a factor of 2 to 3 higher CO2 concentrations and fluxes during the night compared to day-time in the high-DOC lake. The emission fluxes in the low-DOC lake increased from zero to negative values during the day to highly positive values during the end of the night and early morning. The bulk of dissolved (\\< 0.45 m) hydrochemical parameters remained highly stable with 10\\% variation in concentration over 2 days of observation. Overall, the impact of diel cycle on dissolved CH4, DOC, nutrient and metal concentration was below 10\\%. However, neglecting night-time period may underestimate net CO2 emission by ca. 30 to 50\\% in small organic-rich thaw ponds and switch the CO2 exchange from uptake/zero to net emission in larger thermokarst lakes. Given the dominance of large lakes in permafrost regions, the global underestimation of the emission flux may be quite high. As such, monitoring CO2 concentrations and fluxes in thermokarst lakes during months of extended night time (August to October) is mandatory for assessing the net emissions from lentic waters of frozen peatlands.},\n\tlanguage = {en},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Freshwater Biology},\n\tauthor = {Shirokova, L. S. and Payandi-Rolland, D. and Lim, A. G. and Manasypov, R. M. and Allen, J. and Rols, J.-L. and Benezeth, P. and Karlsson, J. and Pokrovsky, O. S.},\n\tmonth = sep,\n\tyear = {2020},\n\tkeywords = {\\#nosource, GHG emission, organic carbon, pond, thermokarst, trace metal, warming},\n\tpages = {886--887},\n}\n\n\n\n\n\n Despite the importance of surface waters of permafrost landscapes in carbon (C) emission, dissolved C, metal storage and export, the diel pattern of dissolved components and gases in thermokarst lakes remain virtually unknown. Here we discovered a factor of 2 to 3 higher CO2 concentrations and fluxes during the night compared to day-time in the high-DOC lake. The emission fluxes in the low-DOC lake increased from zero to negative values during the day to highly positive values during the end of the night and early morning. The bulk of dissolved (< 0.45 m) hydrochemical parameters remained highly stable with 10% variation in concentration over 2 days of observation. Overall, the impact of diel cycle on dissolved CH4, DOC, nutrient and metal concentration was below 10%. However, neglecting night-time period may underestimate net CO2 emission by ca. 30 to 50% in small organic-rich thaw ponds and switch the CO2 exchange from uptake/zero to net emission in larger thermokarst lakes. Given the dominance of large lakes in permafrost regions, the global underestimation of the emission flux may be quite high. As such, monitoring CO2 concentrations and fluxes in thermokarst lakes during months of extended night time (August to October) is mandatory for assessing the net emissions from lentic waters of frozen peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n DOC biodegradation behavior along permafrost affected hydrological continuum.\n \n \n \n \n\n\n \n Payandi-Rolland, D.; Shirokova, L. S.; Tesfa, M.; Benezeth, P.; Lim, A.; Kuzmina, D.; Karlsson, J.; Giesler, R.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Limnology and Freshwater Biology, 4: 874–875. September 2020.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{payandi-rolland_doc_2020,\n\ttitle = {{DOC} biodegradation behavior along permafrost affected hydrological continuum},\n\tvolume = {4},\n\tcopyright = {Copyright (c) 2020 Limnology and Freshwater Biology},\n\tissn = {2658-3518},\n\turl = {http://limnolfwbiol.com/index.php/LFWB/article/view/638},\n\tdoi = {10.31951/2658-3518-2020-A-4-874},\n\tabstract = {In Arctic regions, water bodies are hot spots of dissolved organic carbon (DOC) biodegradation, and their well-known large heterogeneity in the permafrost affected area could lead to a misrepresentation of their importance in the carbon (C) cycle. In this study, the biodegradation potential of various water bodies from two hydrological continuums has been assessed via 15 days aerobic incubation of waters. Results show that biodegradability of waters increases along the continuum while the removal rate of DOC decreases as the consequence of a preferential biodegradation of low molecular weight organic acids (LMWOA). This preferential uptake leads to a relative accumulation of aromatic compounds in the end-members of the continuum. This suggests a shift in the dominantly used pools of DOC along the continuum: a rapidly consumed DOC pool at the beginning of the continuum and a more slowly consumed one at the end of the continuum.},\n\tlanguage = {en},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Freshwater Biology},\n\tauthor = {Payandi-Rolland, D. and Shirokova, L. S. and Tesfa, M. and Benezeth, P. and Lim, A. and Kuzmina, D. and Karlsson, J. and Giesler, R. and Pokrovsky, O. S.},\n\tmonth = sep,\n\tyear = {2020},\n\tkeywords = {\\#nosource, aromaticity},\n\tpages = {874--875},\n}\n\n\n\n\n\n In Arctic regions, water bodies are hot spots of dissolved organic carbon (DOC) biodegradation, and their well-known large heterogeneity in the permafrost affected area could lead to a misrepresentation of their importance in the carbon (C) cycle. In this study, the biodegradation potential of various water bodies from two hydrological continuums has been assessed via 15 days aerobic incubation of waters. Results show that biodegradability of waters increases along the continuum while the removal rate of DOC decreases as the consequence of a preferential biodegradation of low molecular weight organic acids (LMWOA). This preferential uptake leads to a relative accumulation of aromatic compounds in the end-members of the continuum. This suggests a shift in the dominantly used pools of DOC along the continuum: a rapidly consumed DOC pool at the beginning of the continuum and a more slowly consumed one at the end of the continuum.\n
\n\n\n\n \n\n \n \n \n \n \n \n Discrete groundwater inflows influence patterns of nitrogen uptake in a boreal headwater stream.\n \n \n \n \n\n\n \n Lupon, A.; Denfeld, B. A.; Laudon, H.; Leach, J.; and Sponseller, R. A.\n\n\n \n\n\n\n Freshwater Science, 39(2): 228–240. June 2020.\n Publisher: The University of Chicago Press\n\n\n\n
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\n\n\n@article{lupon_discrete_2020,\n\ttitle = {Discrete groundwater inflows influence patterns of nitrogen uptake in a boreal headwater stream},\n\tvolume = {39},\n\tissn = {2161-9549},\n\turl = {https://www.journals.uchicago.edu/doi/abs/10.1086/708521},\n\tdoi = {10.1086/708521},\n\tabstract = {Dissolved organic carbon (DOC) influences stream nitrogen (N) dynamics by regulating the nutrient demand of heterotrophic microbes and mediating their interactions with nitrifiers. However, DOC supply to streams is dynamic in space and time, which may create variability in N dynamics as a result of shifts between heterotrophic and chemoautotrophic influences. To test this, we measured spatial and temporal variation in concentrations and net uptake of dissolved organic nitrogen (DON), ammonium (NH4+), and nitrate (NO3−) along a 1.4-km boreal stream fed by 4 discrete groundwater inflow zones. We also performed constant rate additions of NH4+, with and without acetate, to test the influence of labile DOC availability on N cycling. Groundwater N supply did not drive spatial patterns in N concentrations. However, we observed high rates of net NH4+ uptake at the sub-reach with the greatest groundwater DOC inputs, whereas net nitrification occurred where such inputs were negligible. At the reach scale, net DON and NH4+ uptake increased with greater groundwater discharge, DOC∶DIN, and ecosystem respiration, whereas net nitrification increased with greater DOC aromaticity. Finally, constant rate additions showed that, under increased DOC availability, NH4+ uptake increased 2×, whereas the proportion of NH4+ nitrified decreased from 42 to 15\\%. Together, these observations suggest that nitrification rivals heterotrophic uptake when aromatic DOC promotes heterotrophic carbon limitation. Discrete groundwater inflows and periods of elevated discharge can partially alleviate this limitation by supplying labile DOC from riparian soils. Hence, accounting for these land–water connections, over both time and space, is critical for understanding N dynamics in boreal streams.},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {Freshwater Science},\n\tauthor = {Lupon, Anna and Denfeld, Blaize A. and Laudon, Hjalmar and Leach, Jason and Sponseller, Ryan A.},\n\tmonth = jun,\n\tyear = {2020},\n\tnote = {Publisher: The University of Chicago Press},\n\tkeywords = {\\#nosource, dissolved organic carbon, dissolved organic nitrogen, groundwater inputs, Krycklan, metabolism, net nitrogen uptake, nitrification},\n\tpages = {228--240},\n}\n\n\n\n\n\n Dissolved organic carbon (DOC) influences stream nitrogen (N) dynamics by regulating the nutrient demand of heterotrophic microbes and mediating their interactions with nitrifiers. However, DOC supply to streams is dynamic in space and time, which may create variability in N dynamics as a result of shifts between heterotrophic and chemoautotrophic influences. To test this, we measured spatial and temporal variation in concentrations and net uptake of dissolved organic nitrogen (DON), ammonium (NH4+), and nitrate (NO3−) along a 1.4-km boreal stream fed by 4 discrete groundwater inflow zones. We also performed constant rate additions of NH4+, with and without acetate, to test the influence of labile DOC availability on N cycling. Groundwater N supply did not drive spatial patterns in N concentrations. However, we observed high rates of net NH4+ uptake at the sub-reach with the greatest groundwater DOC inputs, whereas net nitrification occurred where such inputs were negligible. At the reach scale, net DON and NH4+ uptake increased with greater groundwater discharge, DOC∶DIN, and ecosystem respiration, whereas net nitrification increased with greater DOC aromaticity. Finally, constant rate additions showed that, under increased DOC availability, NH4+ uptake increased 2×, whereas the proportion of NH4+ nitrified decreased from 42 to 15%. Together, these observations suggest that nitrification rivals heterotrophic uptake when aromatic DOC promotes heterotrophic carbon limitation. Discrete groundwater inflows and periods of elevated discharge can partially alleviate this limitation by supplying labile DOC from riparian soils. Hence, accounting for these land–water connections, over both time and space, is critical for understanding N dynamics in boreal streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Heterogeneous CO2 and CH4 patterns across space and time in a small boreal lake.\n \n \n \n \n\n\n \n Denfeld, B. A.; Lupon, A.; Sponseller, R. A.; Laudon, H.; and Karlsson, J.\n\n\n \n\n\n\n Inland Waters, 10(3): 348–359. July 2020.\n Publisher: Taylor & Francis _eprint: https://doi.org/10.1080/20442041.2020.1787765\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{denfeld_heterogeneous_2020,\n\ttitle = {Heterogeneous {CO2} and {CH4} patterns across space and time in a small boreal lake},\n\tvolume = {10},\n\tissn = {2044-2041},\n\turl = {https://doi.org/10.1080/20442041.2020.1787765},\n\tdoi = {10.1080/20442041.2020.1787765},\n\tabstract = {Small boreal lakes emit large amounts of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Yet emissions of these greenhouse gases are variable in space and time, in part due to variable within-lake CO2 and CH4 concentrations. To determine the extent and the underlying drivers of this variation, we measured lake water CO2 and CH4 concentrations and estimated associated emissions using spatially discrete water samples collected every 2 weeks from a small boreal lake. On select dates, we also collected groundwater samples from the surrounding catchment. On average, groundwater draining a connected peat mire complex had significantly higher CO2 and CH4 concentrations compared to waters draining forest on mineral soils. However, within the lake, only CH4 concentrations nearshore from the mire complex were significantly elevated. We observed little spatial variability in surface water CO2; however, bottom water CO2 in the pelagic zone was significantly higher than bottom waters at nearshore locations. Overall, temperature, precipitation, and thermal stratification explained temporal patterns of CO2 concentration, whereas hydrology (discharge and precipitation) best predicted the variation in CH4 concentration. Consistent with these different controls, the highest CO2 emission was related to lake turnover at the end of August while the highest CH4 emission was associated with precipitation events at the end of June. These results suggest that annual carbon emissions from small boreal lakes are influenced by temporal variation in weather conditions that regulate thermal stratification and trigger hydrologic land–water connections that supply gases from catchment soils to the lake.},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Inland Waters},\n\tauthor = {Denfeld, Blaize A. and Lupon, Anna and Sponseller, Ryan A. and Laudon, Hjalmar and Karlsson, Jan},\n\tmonth = jul,\n\tyear = {2020},\n\tnote = {Publisher: Taylor \\& Francis\n\\_eprint: https://doi.org/10.1080/20442041.2020.1787765},\n\tkeywords = {\\#nosource, carbon dioxide, carbon emissions, groundwater, lakes, methane, mire},\n\tpages = {348--359},\n}\n\n\n\n\n\n Small boreal lakes emit large amounts of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Yet emissions of these greenhouse gases are variable in space and time, in part due to variable within-lake CO2 and CH4 concentrations. To determine the extent and the underlying drivers of this variation, we measured lake water CO2 and CH4 concentrations and estimated associated emissions using spatially discrete water samples collected every 2 weeks from a small boreal lake. On select dates, we also collected groundwater samples from the surrounding catchment. On average, groundwater draining a connected peat mire complex had significantly higher CO2 and CH4 concentrations compared to waters draining forest on mineral soils. However, within the lake, only CH4 concentrations nearshore from the mire complex were significantly elevated. We observed little spatial variability in surface water CO2; however, bottom water CO2 in the pelagic zone was significantly higher than bottom waters at nearshore locations. Overall, temperature, precipitation, and thermal stratification explained temporal patterns of CO2 concentration, whereas hydrology (discharge and precipitation) best predicted the variation in CH4 concentration. Consistent with these different controls, the highest CO2 emission was related to lake turnover at the end of August while the highest CH4 emission was associated with precipitation events at the end of June. These results suggest that annual carbon emissions from small boreal lakes are influenced by temporal variation in weather conditions that regulate thermal stratification and trigger hydrologic land–water connections that supply gases from catchment soils to the lake.\n
\n\n\n\n \n\n \n \n \n \n \n \n Methane emission offsets carbon dioxide uptake in a small productive lake.\n \n \n \n \n\n\n \n Vachon, D.; Langenegger, T.; Donis, D.; Beaubien, S. E.; and McGinnis, D. F.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 5(6): 384–392. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10161\n\n\n\n
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\n\n\n@article{vachon_methane_2020,\n\ttitle = {Methane emission offsets carbon dioxide uptake in a small productive lake},\n\tvolume = {5},\n\tcopyright = {© 2020 The Authors. Limnology and Oceanography Letters published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {2378-2242},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10161},\n\tdoi = {10.1002/lol2.10161},\n\tabstract = {Here, we investigate the importance of net CH4 production and emissions in the carbon (C) budget of a small productive lake by monitoring CH4, CO2, and O2 for two consecutive years. During the study period, the lake was mostly a net emitter of both CH4 and CO2, while showing positive net ecosystem production. The analyses suggest that during the whole study period, 32\\% ± 26\\% of C produced by net ecosystem production was ultimately converted to CH4 and emitted to the atmosphere. When converted to global warming potential, CH4 emission (in CO2 equivalents) was about 3–10 times higher than CO2 removal from in-lake net ecosystem production over 100-yr and 20-yr time frames, respectively. Although more work in similar systems is needed to generalize these findings, our results provide evidence of the important greenhouse gas imbalance in human-impacted aquatic systems.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Vachon, Dominic and Langenegger, Timon and Donis, Daphne and Beaubien, Stan E. and McGinnis, Daniel F.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10161},\n\tkeywords = {\\#nosource},\n\tpages = {384--392},\n}\n\n\n\n\n\n Here, we investigate the importance of net CH4 production and emissions in the carbon (C) budget of a small productive lake by monitoring CH4, CO2, and O2 for two consecutive years. During the study period, the lake was mostly a net emitter of both CH4 and CO2, while showing positive net ecosystem production. The analyses suggest that during the whole study period, 32% ± 26% of C produced by net ecosystem production was ultimately converted to CH4 and emitted to the atmosphere. When converted to global warming potential, CH4 emission (in CO2 equivalents) was about 3–10 times higher than CO2 removal from in-lake net ecosystem production over 100-yr and 20-yr time frames, respectively. Although more work in similar systems is needed to generalize these findings, our results provide evidence of the important greenhouse gas imbalance in human-impacted aquatic systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Responses of tundra plant community carbon flux to experimental warming, dominant species removal and elevation.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Sanders, N. J.; Dorrepaal, E.; Lindén, E.; Metcalfe, D. B.; Newman, G. S.; Olofsson, J.; Wardle, D. A.; and Classen, A. T.\n\n\n \n\n\n\n Functional Ecology, 34(7): 1497–1506. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.13567\n\n\n\n
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\n\n\n@article{sundqvist_responses_2020,\n\ttitle = {Responses of tundra plant community carbon flux to experimental warming, dominant species removal and elevation},\n\tvolume = {34},\n\tcopyright = {© 2020 The Authors. Functional Ecology published by John Wiley \\& Sons Ltd on behalf of British Ecological Society},\n\tissn = {1365-2435},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.13567},\n\tdoi = {10.1111/1365-2435.13567},\n\tabstract = {Rising temperatures can influence ecosystem processes both directly and indirectly, through effects on plant species and communities. An improved understanding of direct versus indirect effects of warming on ecosystem processes is needed for robust predictions of the impacts of climate change on terrestrial ecosystem carbon (C) dynamics. To explore potential direct and indirect effects of warming on C dynamics in arctic tundra heath, we established a warming (open top chambers) and dominant plant species (Empetrum hermaphroditum Hagerup) removal experiment at a high and low elevation site. We measured the individual and interactive effects of warming, dominant species removal and elevation on plant species cover, the normalized difference vegetation index (NDVI), leaf area index (LAI), temperature, soil moisture and instantaneous net ecosystem CO2 exchange. We hypothesized that ecosystems would be stronger CO2 sinks at the low elevation site, and that warming and species removal would weaken the CO2 sink because warming should increase ecosystem respiration (ER) and species removal should reduce gross primary productivity (GPP). Furthermore, we hypothesized that warming and species removal would have the greatest impact on processes at the high elevation where site temperature should be most limiting and dominant species may buffer the overall community to environmental stress more compared to the low elevation site where plants are more likely to compete with the dominant species. The instantaneous CO2 flux, which reflected a weak CO2 sink, was similar at both elevations. Neither experimental warming nor dominant species removal significantly changed GPP or instantaneous net ecosystem CO2 exchange even though species removal significantly reduced ER, NDVI and LAI. Our results show that even the loss of dominant plant species may not result in significant landscape-scale responses of net ecosystem CO2 exchange to warming. They also show that NDVI and LAI may be limited in their ability to predict changes in GPP in these tundra heaths systems. Our study highlights the need for more detailed vegetation analyses and ground-truthed measurements in order to accurately predict direct and indirect impacts of climatic change on ecosystem C dynamics. A free Plain Language Summary can be found within the Supporting Information of this article.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-27},\n\tjournal = {Functional Ecology},\n\tauthor = {Sundqvist, Maja K. and Sanders, Nathan J. and Dorrepaal, Ellen and Lindén, Elin and Metcalfe, Daniel B. and Newman, Gregory S. and Olofsson, Johan and Wardle, David A. and Classen, Aimée T.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.13567},\n\tkeywords = {\\#nosource, carbon, ecosystem respiration, global warming, gross primary productivity, leaf area index, normalized difference vegetation index, plant–plant interactions},\n\tpages = {1497--1506},\n}\n\n\n\n\n\n Rising temperatures can influence ecosystem processes both directly and indirectly, through effects on plant species and communities. An improved understanding of direct versus indirect effects of warming on ecosystem processes is needed for robust predictions of the impacts of climate change on terrestrial ecosystem carbon (C) dynamics. To explore potential direct and indirect effects of warming on C dynamics in arctic tundra heath, we established a warming (open top chambers) and dominant plant species (Empetrum hermaphroditum Hagerup) removal experiment at a high and low elevation site. We measured the individual and interactive effects of warming, dominant species removal and elevation on plant species cover, the normalized difference vegetation index (NDVI), leaf area index (LAI), temperature, soil moisture and instantaneous net ecosystem CO2 exchange. We hypothesized that ecosystems would be stronger CO2 sinks at the low elevation site, and that warming and species removal would weaken the CO2 sink because warming should increase ecosystem respiration (ER) and species removal should reduce gross primary productivity (GPP). Furthermore, we hypothesized that warming and species removal would have the greatest impact on processes at the high elevation where site temperature should be most limiting and dominant species may buffer the overall community to environmental stress more compared to the low elevation site where plants are more likely to compete with the dominant species. The instantaneous CO2 flux, which reflected a weak CO2 sink, was similar at both elevations. Neither experimental warming nor dominant species removal significantly changed GPP or instantaneous net ecosystem CO2 exchange even though species removal significantly reduced ER, NDVI and LAI. Our results show that even the loss of dominant plant species may not result in significant landscape-scale responses of net ecosystem CO2 exchange to warming. They also show that NDVI and LAI may be limited in their ability to predict changes in GPP in these tundra heaths systems. Our study highlights the need for more detailed vegetation analyses and ground-truthed measurements in order to accurately predict direct and indirect impacts of climatic change on ecosystem C dynamics. A free Plain Language Summary can be found within the Supporting Information of this article.\n
\n\n\n\n \n\n \n \n \n \n \n \n Hot trends and impact in permafrost science.\n \n \n \n \n\n\n \n Sjöberg, Y.; Siewert, M. B.; Rudy, A. C.; Paquette, M.; Bouchard, F.; Malenfant-Lepage, J.; and Fritz, M.\n\n\n \n\n\n\n Permafrost and Periglacial Processes, 31(4): 461–471. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.2047\n\n\n\n
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\n\n\n@article{sjoberg_hot_2020,\n\ttitle = {Hot trends and impact in permafrost science},\n\tvolume = {31},\n\tcopyright = {© 2020 The Authors. Permafrost and Periglacial Processes published by John Wiley \\& Sons Ltd},\n\tissn = {1099-1530},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ppp.2047},\n\tdoi = {10.1002/ppp.2047},\n\tabstract = {An increased interest in Arctic environments, mainly due to climate change, has changed the conditions for permafrost research in recent years. This change has been accompanied by a global increase in scientific publications, as well as a trend towards open access publications. We have analyzed abstracts, titles and keywords for publications on permafrost from 1998 to 2017 to identify developments (topics, impact and collaboration) in the field of permafrost research in light of these changes. Furthermore, to understand how scientists build on and are inspired by each other's work, we have (a) developed citation networks from scientific publications on permafrost and (b) conducted an online survey on inspiration in permafrost science. Our results show an almost 400\\% increase in publications containing the word permafrost in the title, keywords or abstract over the study period, and a strong increase in climate-change-related research in terms of publications and citations. Survey respondents (n = 122) find inspiration not only in scientific journal publications, but to a large extent in books and public outreach materials. We argue that this increase in global-scope issues (i.e., climate change) complementing core permafrost research has provided new incentives for international collaborations and wider communication efforts.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Permafrost and Periglacial Processes},\n\tauthor = {Sjöberg, Ylva and Siewert, Matthias B. and Rudy, Ashley C.A. and Paquette, Michel and Bouchard, Frédéric and Malenfant-Lepage, Julie and Fritz, Michael},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.2047},\n\tkeywords = {\\#nosource, Arctic, bibliometrics, climate change, inspiration, open access, publication trends, science communication},\n\tpages = {461--471},\n}\n\n\n\n\n\n An increased interest in Arctic environments, mainly due to climate change, has changed the conditions for permafrost research in recent years. This change has been accompanied by a global increase in scientific publications, as well as a trend towards open access publications. We have analyzed abstracts, titles and keywords for publications on permafrost from 1998 to 2017 to identify developments (topics, impact and collaboration) in the field of permafrost research in light of these changes. Furthermore, to understand how scientists build on and are inspired by each other's work, we have (a) developed citation networks from scientific publications on permafrost and (b) conducted an online survey on inspiration in permafrost science. Our results show an almost 400% increase in publications containing the word permafrost in the title, keywords or abstract over the study period, and a strong increase in climate-change-related research in terms of publications and citations. Survey respondents (n = 122) find inspiration not only in scientific journal publications, but to a large extent in books and public outreach materials. We argue that this increase in global-scope issues (i.e., climate change) complementing core permafrost research has provided new incentives for international collaborations and wider communication efforts.\n
\n\n\n\n \n\n \n \n \n \n \n \n Scale-dependency of Arctic ecosystem properties revealed by UAV.\n \n \n \n \n\n\n \n Siewert, M. B.; and Olofsson, J.\n\n\n \n\n\n\n Environmental Research Letters, 15(9): 094030. August 2020.\n Publisher: IOP Publishing\n\n\n\n
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\n\n\n@article{siewert_scale-dependency_2020,\n\ttitle = {Scale-dependency of {Arctic} ecosystem properties revealed by {UAV}},\n\tvolume = {15},\n\tissn = {1748-9326},\n\turl = {https://dx.doi.org/10.1088/1748-9326/aba20b},\n\tdoi = {10.1088/1748-9326/aba20b},\n\tabstract = {In the face of climate change, it is important to estimate changes in key ecosystem properties such as plant biomass and gross primary productivity (GPP). Ground truth estimates and especially experiments are performed at small spatial scales (0.01–1 m2) and scaled up using coarse scale satellite remote sensing products. This will lead to a scaling bias for non-linearly related properties in heterogeneous environments when the relationships are not developed at the same spatial scale as the remote sensing products. We show that unmanned aerial vehicles (UAVs) can reliably measure normalized difference vegetation index (NDVI) at centimeter resolution even in highly heterogeneous Arctic tundra terrain. This reveals that this scaling bias increases most at very fine resolution, but UAVs can overcome this by generating remote sensing products at the same scales as ecological changes occur. Using ground truth data generated at 0.0625 m2 and 1 m2 with Landsat 30 m scale satellite imagery the resulting underestimation is large (8.9\\%–17.0\\% for biomass and 5.0\\%–9.7\\% for GPP600) and of a magnitude comparable to the expected effects of decades of climate change. Methods to correct this upscaling bias exist but rely on sub-pixel information. Our data shows that this scale-dependency will vary strongly between areas and across seasons, making it hard to derive generalized functions compensating for it. This is particularly relevant to Arctic greening with a predominantly heterogeneous land cover, strong seasonality and much experimental research at sub-meter scale, but also applies to other heterogeneous landscapes. These results demonstrate the value of UAVs for satellite validation. UAVs can bridge between plot scale used in ecological field investigations and coarse scale in satellite monitoring relevant for Earth System Models. Since future climate changes are expected to alter landscape heterogeneity, seasonally updated UAV imagery will be an essential tool to correctly predict landscape-scale changes in ecosystem properties.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2024-03-27},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Siewert, Matthias B. and Olofsson, Johan},\n\tmonth = aug,\n\tyear = {2020},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {094030},\n}\n\n\n\n\n\n In the face of climate change, it is important to estimate changes in key ecosystem properties such as plant biomass and gross primary productivity (GPP). Ground truth estimates and especially experiments are performed at small spatial scales (0.01–1 m2) and scaled up using coarse scale satellite remote sensing products. This will lead to a scaling bias for non-linearly related properties in heterogeneous environments when the relationships are not developed at the same spatial scale as the remote sensing products. We show that unmanned aerial vehicles (UAVs) can reliably measure normalized difference vegetation index (NDVI) at centimeter resolution even in highly heterogeneous Arctic tundra terrain. This reveals that this scaling bias increases most at very fine resolution, but UAVs can overcome this by generating remote sensing products at the same scales as ecological changes occur. Using ground truth data generated at 0.0625 m2 and 1 m2 with Landsat 30 m scale satellite imagery the resulting underestimation is large (8.9%–17.0% for biomass and 5.0%–9.7% for GPP600) and of a magnitude comparable to the expected effects of decades of climate change. Methods to correct this upscaling bias exist but rely on sub-pixel information. Our data shows that this scale-dependency will vary strongly between areas and across seasons, making it hard to derive generalized functions compensating for it. This is particularly relevant to Arctic greening with a predominantly heterogeneous land cover, strong seasonality and much experimental research at sub-meter scale, but also applies to other heterogeneous landscapes. These results demonstrate the value of UAVs for satellite validation. UAVs can bridge between plot scale used in ecological field investigations and coarse scale in satellite monitoring relevant for Earth System Models. Since future climate changes are expected to alter landscape heterogeneity, seasonally updated UAV imagery will be an essential tool to correctly predict landscape-scale changes in ecosystem properties.\n
\n\n\n\n \n\n \n \n \n \n \n \n The responses of moss-associated nitrogen fixation and belowground microbial community to chronic Mo and P supplements in subarctic dry heaths.\n \n \n \n \n\n\n \n Rousk, K.; and Rousk, J.\n\n\n \n\n\n\n Plant and Soil, 451(1): 261–276. June 2020.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{rousk_responses_2020,\n\ttitle = {The responses of moss-associated nitrogen fixation and belowground microbial community to chronic {Mo} and {P} supplements in subarctic dry heaths},\n\tvolume = {451},\n\tissn = {1573-5036},\n\turl = {https://doi.org/10.1007/s11104-020-04492-6},\n\tdoi = {10.1007/s11104-020-04492-6},\n\tabstract = {Although nitrogen (N) fixation by moss-associated bacteria is the main source of new N in N-limited ecosystems like arctic tundra, we do not know which nutrient, molybdenum (Mo) or phosphorus (P), is rate-limiting for sustaining this process in the long-term. Further, how moss-associated N2 fixation impacts the belowground microbial regulation of decomposition remains unresolved.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Plant and Soil},\n\tauthor = {Rousk, Kathrin and Rousk, Johannes},\n\tmonth = jun,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Bryophytes, Cyanobacteria, Nitrogen fixation, Nutrient limitation, Soil fungal and bacterial growth},\n\tpages = {261--276},\n}\n\n\n\n\n\n Although nitrogen (N) fixation by moss-associated bacteria is the main source of new N in N-limited ecosystems like arctic tundra, we do not know which nutrient, molybdenum (Mo) or phosphorus (P), is rate-limiting for sustaining this process in the long-term. Further, how moss-associated N2 fixation impacts the belowground microbial regulation of decomposition remains unresolved.\n
\n\n\n\n \n\n \n \n \n \n \n \n Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape.\n \n \n \n \n\n\n \n Parker, T. C.; Clemmensen, K. E.; Friggens, N. L.; Hartley, I. P.; Johnson, D.; Lindahl, B. D.; Olofsson, J.; Siewert, M. B.; Street, L. E.; Subke, J.; and Wookey, P. A.\n\n\n \n\n\n\n New Phytologist, 227(6): 1818–1830. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/nph.16573\n\n\n\n
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\n\n\n@article{parker_rhizosphere_2020,\n\ttitle = {Rhizosphere allocation by canopy-forming species dominates soil {CO2} efflux in a subarctic landscape},\n\tvolume = {227},\n\tcopyright = {© 2020 The Authors. New Phytologist © 2020 New Phytologist Trust},\n\tissn = {1469-8137},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.16573},\n\tdoi = {10.1111/nph.16573},\n\tabstract = {In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation controls on soil CO2 efflux remain poorly resolved. In order to identify the role of canopy-forming species in belowground C dynamics, we conducted a girdling experiment with plots distributed across 1 km2 of treeline birch (Betula pubescens) forest and willow (Salix lapponum) patches in northern Sweden and quantified the contribution of canopy vegetation to soil CO2 fluxes and belowground productivity. Girdling birches reduced total soil CO2 efflux in the peak growing season by 53\\%, which is double the expected amount, given that trees contribute only half of the total leaf area in the forest. Root and mycorrhizal mycelial production also decreased substantially. At peak season, willow shrubs contributed 38\\% to soil CO2 efflux in their patches. Our findings indicate that C, recently fixed by trees and tall shrubs, makes a substantial contribution to soil respiration. It is critically important that these processes are taken into consideration in the context of a greening arctic because productivity and ecosystem C sequestration are not synonymous.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {New Phytologist},\n\tauthor = {Parker, Thomas C. and Clemmensen, Karina E. and Friggens, Nina L. and Hartley, Iain P. and Johnson, David and Lindahl, Björn D. and Olofsson, Johan and Siewert, Matthias B. and Street, Lorna E. and Subke, Jens-Arne and Wookey, Philip A.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/nph.16573},\n\tkeywords = {\\#nosource, Arctic, ectomycorrhizal fungi, girdling, rhizosphere, shrub expansion, soil CO2 efflux, treeline},\n\tpages = {1818--1830},\n}\n\n\n\n\n\n In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation controls on soil CO2 efflux remain poorly resolved. In order to identify the role of canopy-forming species in belowground C dynamics, we conducted a girdling experiment with plots distributed across 1 km2 of treeline birch (Betula pubescens) forest and willow (Salix lapponum) patches in northern Sweden and quantified the contribution of canopy vegetation to soil CO2 fluxes and belowground productivity. Girdling birches reduced total soil CO2 efflux in the peak growing season by 53%, which is double the expected amount, given that trees contribute only half of the total leaf area in the forest. Root and mycorrhizal mycelial production also decreased substantially. At peak season, willow shrubs contributed 38% to soil CO2 efflux in their patches. Our findings indicate that C, recently fixed by trees and tall shrubs, makes a substantial contribution to soil respiration. It is critically important that these processes are taken into consideration in the context of a greening arctic because productivity and ecosystem C sequestration are not synonymous.\n
\n\n\n\n \n\n \n \n \n \n \n \n Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance.\n \n \n \n \n\n\n \n Olid, C.; Klaminder, J.; Monteux, S.; Johansson, M.; and Dorrepaal, E.\n\n\n \n\n\n\n Global Change Biology, 26(10): 5886–5898. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15283\n\n\n\n
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\n\n\n@article{olid_decade_2020,\n\ttitle = {Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance},\n\tvolume = {26},\n\tcopyright = {© 2020 The Authors. Global Change Biology published by John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15283},\n\tdoi = {10.1111/gcb.15283},\n\tabstract = {Thicker snowpacks and their insulation effects cause winter-warming and invoke thaw of permafrost ecosystems. Temperature-dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow-free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long-term net C balance (net ecosystem production) in a subarctic peat plateau subjected to 10 years of experimental winter-warming. By combining 210Pb and 14Cdating of peat cores with peat growth models, we investigated thawing effects on year-round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter-warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent waterlogging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long-term responses of whole-year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Olid, Carolina and Klaminder, Jonatan and Monteux, Sylvain and Johansson, Margareta and Dorrepaal, Ellen},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15283},\n\tkeywords = {\\#nosource, age–depth modelling, carbon accumulation, carbon cycle, climate change, decomposition, peat dating, permafrost thawing, production, snow addition, winter-warming},\n\tpages = {5886--5898},\n}\n\n\n\n\n\n Thicker snowpacks and their insulation effects cause winter-warming and invoke thaw of permafrost ecosystems. Temperature-dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow-free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long-term net C balance (net ecosystem production) in a subarctic peat plateau subjected to 10 years of experimental winter-warming. By combining 210Pb and 14Cdating of peat cores with peat growth models, we investigated thawing effects on year-round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter-warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent waterlogging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long-term responses of whole-year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.\n
\n\n\n\n \n\n \n \n \n \n \n \n SoilTemp: A global database of near-surface temperature.\n \n \n \n \n\n\n \n Lembrechts, J. J.; Aalto, J.; Ashcroft, M. B.; De Frenne, P.; Kopecký, M.; Lenoir, J.; Luoto, M.; Maclean, I. M. D.; Roupsard, O.; Fuentes-Lillo, E.; García, R. A.; Pellissier, L.; Pitteloud, C.; Alatalo, J. M.; Smith, S. W.; Björk, R. G.; Muffler, L.; Ratier Backes, A.; Cesarz, S.; Gottschall, F.; Okello, J.; Urban, J.; Plichta, R.; Svátek, M.; Phartyal, S. S.; Wipf, S.; Eisenhauer, N.; Pușcaș, M.; Turtureanu, P. D.; Varlagin, A.; Dimarco, R. D.; Jump, A. S.; Randall, K.; Dorrepaal, E.; Larson, K.; Walz, J.; Vitale, L.; Svoboda, M.; Finger Higgens, R.; Halbritter, A. H.; Curasi, S. R.; Klupar, I.; Koontz, A.; Pearse, W. D.; Simpson, E.; Stemkovski, M.; Jessen Graae, B.; Vedel Sørensen, M.; Høye, T. T.; Fernández Calzado, M. R.; Lorite, J.; Carbognani, M.; Tomaselli, M.; Forte, T. G. W.; Petraglia, A.; Haesen, S.; Somers, B.; Van Meerbeek, K.; Björkman, M. P.; Hylander, K.; Merinero, S.; Gharun, M.; Buchmann, N.; Dolezal, J.; Matula, R.; Thomas, A. D.; Bailey, J. J.; Ghosn, D.; Kazakis, G.; de Pablo, M. A.; Kemppinen, J.; Niittynen, P.; Rew, L.; Seipel, T.; Larson, C.; Speed, J. D. M.; Ardö, J.; Cannone, N.; Guglielmin, M.; Malfasi, F.; Bader, M. Y.; Canessa, R.; Stanisci, A.; Kreyling, J.; Schmeddes, J.; Teuber, L.; Aschero, V.; Čiliak, M.; Máliš, F.; De Smedt, P.; Govaert, S.; Meeussen, C.; Vangansbeke, P.; Gigauri, K.; Lamprecht, A.; Pauli, H.; Steinbauer, K.; Winkler, M.; Ueyama, M.; Nuñez, M. A.; Ursu, T.; Haider, S.; Wedegärtner, R. E. M.; Smiljanic, M.; Trouillier, M.; Wilmking, M.; Altman, J.; Brůna, J.; Hederová, L.; Macek, M.; Man, M.; Wild, J.; Vittoz, P.; Pärtel, M.; Barančok, P.; Kanka, R.; Kollár, J.; Palaj, A.; Barros, A.; Mazzolari, A. C.; Bauters, M.; Boeckx, P.; Benito Alonso, J.; Zong, S.; Di Cecco, V.; Sitková, Z.; Tielbörger, K.; van den Brink, L.; Weigel, R.; Homeier, J.; Dahlberg, C. J.; Medinets, S.; Medinets, V.; De Boeck, H. J.; Portillo-Estrada, M.; Verryckt, L. T.; Milbau, A.; Daskalova, G. N.; Thomas, H. J. D.; Myers-Smith, I. H.; Blonder, B.; Stephan, J. G.; Descombes, P.; Zellweger, F.; Frei, E. R.; Heinesch, B.; Andrews, C.; Dick, J.; Siebicke, L.; Rocha, A.; Senior, R. A.; Rixen, C.; Jimenez, J. J.; Boike, J.; Pauchard, A.; Scholten, T.; Scheffers, B.; Klinges, D.; Basham, E. W.; Zhang, J.; Zhang, Z.; Géron, C.; Fazlioglu, F.; Candan, O.; Sallo Bravo, J.; Hrbacek, F.; Laska, K.; Cremonese, E.; Haase, P.; Moyano, F. E.; Rossi, C.; and Nijs, I.\n\n\n \n\n\n\n Global Change Biology, 26(11): 6616–6629. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15123\n\n\n\n
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\n\n\n@article{lembrechts_soiltemp_2020,\n\ttitle = {{SoilTemp}: {A} global database of near-surface temperature},\n\tvolume = {26},\n\tcopyright = {© 2020 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\tshorttitle = {{SoilTemp}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15123},\n\tdoi = {10.1111/gcb.15123},\n\tabstract = {Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries across all key biomes. The database will pave the way toward an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Lembrechts, Jonas J. and Aalto, Juha and Ashcroft, Michael B. and De Frenne, Pieter and Kopecký, Martin and Lenoir, Jonathan and Luoto, Miska and Maclean, Ilya M. D. and Roupsard, Olivier and Fuentes-Lillo, Eduardo and García, Rafael A. and Pellissier, Loïc and Pitteloud, Camille and Alatalo, Juha M. and Smith, Stuart W. and Björk, Robert G. and Muffler, Lena and Ratier Backes, Amanda and Cesarz, Simone and Gottschall, Felix and Okello, Joseph and Urban, Josef and Plichta, Roman and Svátek, Martin and Phartyal, Shyam S. and Wipf, Sonja and Eisenhauer, Nico and Pușcaș, Mihai and Turtureanu, Pavel D. and Varlagin, Andrej and Dimarco, Romina D. and Jump, Alistair S. and Randall, Krystal and Dorrepaal, Ellen and Larson, Keith and Walz, Josefine and Vitale, Luca and Svoboda, Miroslav and Finger Higgens, Rebecca and Halbritter, Aud H. and Curasi, Salvatore R. and Klupar, Ian and Koontz, Austin and Pearse, William D. and Simpson, Elizabeth and Stemkovski, Michael and Jessen Graae, Bente and Vedel Sørensen, Mia and Høye, Toke T. and Fernández Calzado, M. Rosa and Lorite, Juan and Carbognani, Michele and Tomaselli, Marcello and Forte, T'ai G. W. and Petraglia, Alessandro and Haesen, Stef and Somers, Ben and Van Meerbeek, Koenraad and Björkman, Mats P. and Hylander, Kristoffer and Merinero, Sonia and Gharun, Mana and Buchmann, Nina and Dolezal, Jiri and Matula, Radim and Thomas, Andrew D. and Bailey, Joseph J. and Ghosn, Dany and Kazakis, George and de Pablo, Miguel A. and Kemppinen, Julia and Niittynen, Pekka and Rew, Lisa and Seipel, Tim and Larson, Christian and Speed, James D. M. and Ardö, Jonas and Cannone, Nicoletta and Guglielmin, Mauro and Malfasi, Francesco and Bader, Maaike Y. and Canessa, Rafaella and Stanisci, Angela and Kreyling, Juergen and Schmeddes, Jonas and Teuber, Laurenz and Aschero, Valeria and Čiliak, Marek and Máliš, František and De Smedt, Pallieter and Govaert, Sanne and Meeussen, Camille and Vangansbeke, Pieter and Gigauri, Khatuna and Lamprecht, Andrea and Pauli, Harald and Steinbauer, Klaus and Winkler, Manuela and Ueyama, Masahito and Nuñez, Martin A. and Ursu, Tudor-Mihai and Haider, Sylvia and Wedegärtner, Ronja E. M. and Smiljanic, Marko and Trouillier, Mario and Wilmking, Martin and Altman, Jan and Brůna, Josef and Hederová, Lucia and Macek, Martin and Man, Matěj and Wild, Jan and Vittoz, Pascal and Pärtel, Meelis and Barančok, Peter and Kanka, Róbert and Kollár, Jozef and Palaj, Andrej and Barros, Agustina and Mazzolari, Ana C. and Bauters, Marijn and Boeckx, Pascal and Benito Alonso, José-Luis and Zong, Shengwei and Di Cecco, Valter and Sitková, Zuzana and Tielbörger, Katja and van den Brink, Liesbeth and Weigel, Robert and Homeier, Jürgen and Dahlberg, C. Johan and Medinets, Sergiy and Medinets, Volodymyr and De Boeck, Hans J. and Portillo-Estrada, Miguel and Verryckt, Lore T. and Milbau, Ann and Daskalova, Gergana N. and Thomas, Haydn J. D. and Myers-Smith, Isla H. and Blonder, Benjamin and Stephan, Jörg G. and Descombes, Patrice and Zellweger, Florian and Frei, Esther R. and Heinesch, Bernard and Andrews, Christopher and Dick, Jan and Siebicke, Lukas and Rocha, Adrian and Senior, Rebecca A. and Rixen, Christian and Jimenez, Juan J. and Boike, Julia and Pauchard, Aníbal and Scholten, Thomas and Scheffers, Brett and Klinges, David and Basham, Edmund W. and Zhang, Jian and Zhang, Zhaochen and Géron, Charly and Fazlioglu, Fatih and Candan, Onur and Sallo Bravo, Jhonatan and Hrbacek, Filip and Laska, Kamil and Cremonese, Edoardo and Haase, Peter and Moyano, Fernando E. and Rossi, Christian and Nijs, Ivan},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15123},\n\tkeywords = {\\#nosource, climate change, database, ecosystem processes, microclimate, soil climate, species distributions, temperature, topoclimate},\n\tpages = {6616--6629},\n}\n\n\n\n\n\n Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries across all key biomes. The database will pave the way toward an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.\n
\n\n\n\n \n\n \n \n \n \n \n \n The old and the new: evaluating performance of acoustic telemetry systems in tracking migrating Atlantic salmon (Salmo salar) smolt and European eel (Anguilla anguilla) around hydropower facilities.\n \n \n \n \n\n\n \n Leander, J.; Klaminder, J.; Jonsson, M.; Brodin, T.; Leonardsson, K.; and Hellström, G.\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences, 77(1): 177–187. January 2020.\n Publisher: NRC Research Press\n\n\n\n
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\n\n\n@article{leander_old_2020,\n\ttitle = {The old and the new: evaluating performance of acoustic telemetry systems in tracking migrating {Atlantic} salmon ({Salmo} salar) smolt and {European} eel ({Anguilla} anguilla) around hydropower facilities},\n\tvolume = {77},\n\tissn = {0706-652X},\n\tshorttitle = {The old and the new},\n\turl = {https://cdnsciencepub.com/doi/abs/10.1139/cjfas-2019-0058},\n\tdoi = {10.1139/cjfas-2019-0058},\n\tabstract = {Acoustic telemetry represents the state-of-the-art technology for monitoring behaviour of aquatic organisms in the wild. Yet, the performance of different systems is rarely evaluated across species and environments. In this study, we evaluate two different acoustic telemetry systems, a commonly used analogue pulse-position-modulation-based system (VEMCO PPM) and a newly developed high-residency digital binary phase shift key-based system (VEMCO HR2), in ability to track downstream migrating Atlantic salmon smolt (Salmo salar) and European eel (Anguilla anguilla) around hydropower facilities. High-precision GPS were used to evaluate precision and accuracy of hyperbolically positioned data derived from each system. The PPM-based system had higher detection range than HR2 and generated more positions per transmission for eels migrating close to bottom than for surface-oriented salmon smolts. HR2 generated tenfold more positions per time unit than PPM, were less sensitive to noise, achieved submetre positional precision, and were considerably more accurate than PPM-derived positions after filtering. HR2 was deemed more capable than PPM in fine-scale positioning at moderate distances at hydropower facilities.},\n\tnumber = {1},\n\turldate = {2024-03-26},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Leander, Johan and Klaminder, Jonatan and Jonsson, Micael and Brodin, Tomas and Leonardsson, Kjell and Hellström, Gustav},\n\tmonth = jan,\n\tyear = {2020},\n\tnote = {Publisher: NRC Research Press},\n\tkeywords = {\\#nosource},\n\tpages = {177--187},\n}\n\n\n\n\n\n Acoustic telemetry represents the state-of-the-art technology for monitoring behaviour of aquatic organisms in the wild. Yet, the performance of different systems is rarely evaluated across species and environments. In this study, we evaluate two different acoustic telemetry systems, a commonly used analogue pulse-position-modulation-based system (VEMCO PPM) and a newly developed high-residency digital binary phase shift key-based system (VEMCO HR2), in ability to track downstream migrating Atlantic salmon smolt (Salmo salar) and European eel (Anguilla anguilla) around hydropower facilities. High-precision GPS were used to evaluate precision and accuracy of hyperbolically positioned data derived from each system. The PPM-based system had higher detection range than HR2 and generated more positions per transmission for eels migrating close to bottom than for surface-oriented salmon smolts. HR2 generated tenfold more positions per time unit than PPM, were less sensitive to noise, achieved submetre positional precision, and were considerably more accurate than PPM-derived positions after filtering. HR2 was deemed more capable than PPM in fine-scale positioning at moderate distances at hydropower facilities.\n
\n\n\n\n \n\n \n \n \n \n \n \n Background insect herbivory increases with local elevation but makes minor contribution to element cycling along natural gradients in the Subarctic.\n \n \n \n \n\n\n \n Kristensen, J. A.; Michelsen, A.; and Metcalfe, D. B.\n\n\n \n\n\n\n Ecology and Evolution, 10(20): 11684–11698. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.6803\n\n\n\n
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\n\n\n@article{kristensen_background_2020,\n\ttitle = {Background insect herbivory increases with local elevation but makes minor contribution to element cycling along natural gradients in the {Subarctic}},\n\tvolume = {10},\n\tcopyright = {© 2020 The Authors. Ecology and Evolution published by John Wiley \\& Sons Ltd},\n\tissn = {2045-7758},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.6803},\n\tdoi = {10.1002/ece3.6803},\n\tabstract = {Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high-latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was 1.6\\% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1–2 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.},\n\tlanguage = {en},\n\tnumber = {20},\n\turldate = {2024-03-26},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Kristensen, Jeppe A. and Michelsen, Anders and Metcalfe, Daniel B.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.6803},\n\tkeywords = {\\#nosource, Subarctic mountain birch forest, carbon cycling, fast cycle versus slow cycle, insect herbivory, nutrient cycling, space-for-time substitution},\n\tpages = {11684--11698},\n}\n\n\n\n\n\n Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high-latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was 1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1–2 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.\n
\n\n\n\n \n\n \n \n \n \n \n \n Challenges of predicting gas transfer velocity from wind measurements over global lakes.\n \n \n \n \n\n\n \n Klaus, M.; and Vachon, D.\n\n\n \n\n\n\n Aquatic Sciences, 82(3): 53. May 2020.\n \n\n\n\n
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\n\n\n@article{klaus_challenges_2020,\n\ttitle = {Challenges of predicting gas transfer velocity from wind measurements over global lakes},\n\tvolume = {82},\n\tissn = {1420-9055},\n\turl = {https://doi.org/10.1007/s00027-020-00729-9},\n\tdoi = {10.1007/s00027-020-00729-9},\n\tabstract = {Estimating air–water gas transfer velocities (k) is integral to understand biogeochemical and ecological processes in aquatic systems. In lakes, k is commonly predicted using wind-based empirical models, however, their predictive performance under conditions that differ from their original calibration remains largely unassessed. Here, we collected 2222 published k estimates derived from various methods in 46 globally distributed lakes to (1) evaluate the predictions of a selection of six available wind-speed based k models for lakes and (2) explore and develop new empirical models to predict k over global lakes. We found that selected k models generally performed poorly in predicting k in lakes. Model predictions were more accurate than simply assuming a mean k in only 2–39\\% of all lakes, however, we could not identify with confidence the specific conditions in which some models outperformed others. We developed new wind-based models in which additional variables describing the spatial coverage of k estimates and the lake size and shape had a significant effect on the wind speed-k relationship. Although these new models did not fit the global dataset significantly better than previous k models, they generate overall less biased predictions for global lakes. We further provide explicit estimates of prediction errors that integrate methodological and lake-specific uncertainties. Our results highlight the potential limits when using wind-based models to predict k across lakes and urge scientists to properly account for prediction errors, or measure k directly in the field whenever possible.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Klaus, Marcus and Vachon, Dominic},\n\tmonth = may,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Air–water gas exchange, Lake gas flux, Model assessment, Reaeration, Wind speed, k 600},\n\tpages = {53},\n}\n\n\n\n\n\n Estimating air–water gas transfer velocities (k) is integral to understand biogeochemical and ecological processes in aquatic systems. In lakes, k is commonly predicted using wind-based empirical models, however, their predictive performance under conditions that differ from their original calibration remains largely unassessed. Here, we collected 2222 published k estimates derived from various methods in 46 globally distributed lakes to (1) evaluate the predictions of a selection of six available wind-speed based k models for lakes and (2) explore and develop new empirical models to predict k over global lakes. We found that selected k models generally performed poorly in predicting k in lakes. Model predictions were more accurate than simply assuming a mean k in only 2–39% of all lakes, however, we could not identify with confidence the specific conditions in which some models outperformed others. We developed new wind-based models in which additional variables describing the spatial coverage of k estimates and the lake size and shape had a significant effect on the wind speed-k relationship. Although these new models did not fit the global dataset significantly better than previous k models, they generate overall less biased predictions for global lakes. We further provide explicit estimates of prediction errors that integrate methodological and lake-specific uncertainties. Our results highlight the potential limits when using wind-based models to predict k across lakes and urge scientists to properly account for prediction errors, or measure k directly in the field whenever possible.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stand age and climate influence forest ecosystem service delivery and multifunctionality.\n \n \n \n \n\n\n \n Jonsson, M.; Bengtsson, J.; Moen, J.; Gamfeldt, L.; and Snäll, T.\n\n\n \n\n\n\n Environmental Research Letters, 15(9): 0940a8. September 2020.\n Publisher: IOP Publishing\n\n\n\n
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\n\n\n@article{jonsson_stand_2020,\n\ttitle = {Stand age and climate influence forest ecosystem service delivery and multifunctionality},\n\tvolume = {15},\n\tissn = {1748-9326},\n\turl = {https://dx.doi.org/10.1088/1748-9326/abaf1c},\n\tdoi = {10.1088/1748-9326/abaf1c},\n\tabstract = {We examine how levels of multiple ecosystem services (ESs) change with succession in forests with different tree species composition. More specifically we ask how ecosystem age interacts with environmental conditions to regulate ES delivery. Using the nationwide Swedish forest inventory, comprising boreal and temperate regions, we investigated how levels of six provisioning, regulating, recreational, and/or cultural forest ESs changed with forest age (10–185 years) in stands of different tree species composition. We also tested whether the number of ESs delivered (i.e. multifunctionality) changed substantially with stand age, using different threshold levels for ES delivery. Accounting for environmental conditions and stand properties, we found that levels of single ESs changed with stand age. Tree biomass production usually peaked in young to medium aged stands. In contrast, production of berries and game, and services related to biodiversity, were typically highest in old stands (120–185 years). Consistent with this strong temporal tradeoff, multifunctionality at lower threshold levels increased with stand age in most monocultures and mixtures, with the highest multifunctionality being reached somewhere between 100 and 185 years, depending on tree species composition. This was not evident for the highest threshold ES level (the top-20\\%), however. Moreover, multifunctionality usually decreased with warmer climatic conditions, with the exception of spruce–pine–birch mixtures. Taken together, our results show that a reduced forest age, e.g. due to forestry targeting early harvest of stands, most likely would limit the delivery of several ESs valued by society and result in less multifunctional forests. To maintain the capacity of forests to deliver high levels of multiple ESs, the role of stand age and tree species composition should be considered in decisions on how to manage future forests.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2024-03-26},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Jonsson, Micael and Bengtsson, Jan and Moen, Jon and Gamfeldt, Lars and Snäll, Tord},\n\tmonth = sep,\n\tyear = {2020},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {0940a8},\n}\n\n\n\n\n\n We examine how levels of multiple ecosystem services (ESs) change with succession in forests with different tree species composition. More specifically we ask how ecosystem age interacts with environmental conditions to regulate ES delivery. Using the nationwide Swedish forest inventory, comprising boreal and temperate regions, we investigated how levels of six provisioning, regulating, recreational, and/or cultural forest ESs changed with forest age (10–185 years) in stands of different tree species composition. We also tested whether the number of ESs delivered (i.e. multifunctionality) changed substantially with stand age, using different threshold levels for ES delivery. Accounting for environmental conditions and stand properties, we found that levels of single ESs changed with stand age. Tree biomass production usually peaked in young to medium aged stands. In contrast, production of berries and game, and services related to biodiversity, were typically highest in old stands (120–185 years). Consistent with this strong temporal tradeoff, multifunctionality at lower threshold levels increased with stand age in most monocultures and mixtures, with the highest multifunctionality being reached somewhere between 100 and 185 years, depending on tree species composition. This was not evident for the highest threshold ES level (the top-20%), however. Moreover, multifunctionality usually decreased with warmer climatic conditions, with the exception of spruce–pine–birch mixtures. Taken together, our results show that a reduced forest age, e.g. due to forestry targeting early harvest of stands, most likely would limit the delivery of several ESs valued by society and result in less multifunctional forests. To maintain the capacity of forests to deliver high levels of multiple ESs, the role of stand age and tree species composition should be considered in decisions on how to manage future forests.\n
\n\n\n\n \n\n \n \n \n \n \n \n Mammalian herbivory shapes intraspecific trait responses to warmer climate and nutrient enrichment.\n \n \n \n \n\n\n \n Jessen, M.; Kaarlejärvi, E.; Olofsson, J.; and Eskelinen, A.\n\n\n \n\n\n\n Global Change Biology, 26(12): 6742–6752. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15378\n\n\n\n
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\n\n\n@article{jessen_mammalian_2020,\n\ttitle = {Mammalian herbivory shapes intraspecific trait responses to warmer climate and nutrient enrichment},\n\tvolume = {26},\n\tcopyright = {© 2020 The Authors. Global Change Biology published by John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15378},\n\tdoi = {10.1111/gcb.15378},\n\tabstract = {Variation in intraspecific traits is one important mechanism that can allow plant species to respond to global changes. Understanding plant trait responses to environmental changes such as grazing patterns, nutrient enrichment and climate warming is, thus, essential for predicting the composition of future plant communities. We measured traits of eight common tundra species in a fully factorial field experiment with mammalian herbivore exclusion, fertilization, and passive warming, and assessed how trait responsiveness to the treatments was associated with abundance changes in those treatments. Herbivory exhibited the strongest impact on traits. Exclusion of herbivores increased vegetative plant height by 50\\% and specific leaf area (SLA) by 19\\%, and decreased foliar C:N by 11\\%; fertilization and warming also increased height and SLA but to a smaller extent. Herbivory also modulated intraspecific height, SLA and foliar C:N responses to fertilization and warming, and these interactions were species-specific. Furthermore, herbivory affected how trait change translated into relative abundance change: increased height under warming and fertilization was more positively related to abundance change inside fences than in grazed plots. Our findings highlight the key role of mammalian herbivory when assessing intraspecific trait change in tundra and its consequences for plant performance under global changes.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Jessen, Maria-Theresa and Kaarlejärvi, Elina and Olofsson, Johan and Eskelinen, Anu},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15378},\n\tkeywords = {\\#nosource, anthropogenic change, climate warming, grazing, herbivory, intraspecific trait plasticity, nutrient addition, open-top chamber, plant performance, reindeer, trait–environment relationship},\n\tpages = {6742--6752},\n}\n\n\n\n\n\n Variation in intraspecific traits is one important mechanism that can allow plant species to respond to global changes. Understanding plant trait responses to environmental changes such as grazing patterns, nutrient enrichment and climate warming is, thus, essential for predicting the composition of future plant communities. We measured traits of eight common tundra species in a fully factorial field experiment with mammalian herbivore exclusion, fertilization, and passive warming, and assessed how trait responsiveness to the treatments was associated with abundance changes in those treatments. Herbivory exhibited the strongest impact on traits. Exclusion of herbivores increased vegetative plant height by 50% and specific leaf area (SLA) by 19%, and decreased foliar C:N by 11%; fertilization and warming also increased height and SLA but to a smaller extent. Herbivory also modulated intraspecific height, SLA and foliar C:N responses to fertilization and warming, and these interactions were species-specific. Furthermore, herbivory affected how trait change translated into relative abundance change: increased height under warming and fertilization was more positively related to abundance change inside fences than in grazed plots. Our findings highlight the key role of mammalian herbivory when assessing intraspecific trait change in tundra and its consequences for plant performance under global changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global changes may be promoting a rise in select cyanobacteria in nutrient-poor northern lakes.\n \n \n \n \n\n\n \n Freeman, E. C.; Creed, I. F.; Jones, B.; and Bergström, A.\n\n\n \n\n\n\n Global Change Biology, 26(9): 4966–4987. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15189\n\n\n\n
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\n\n\n@article{freeman_global_2020,\n\ttitle = {Global changes may be promoting a rise in select cyanobacteria in nutrient-poor northern lakes},\n\tvolume = {26},\n\tcopyright = {© 2020 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15189},\n\tdoi = {10.1111/gcb.15189},\n\tabstract = {The interacting effects of global changes—including increased temperature, altered precipitation, reduced acidification and increased dissolved organic matter loads to lakes—are anticipated to create favourable environmental conditions for cyanobacteria in northern lakes. However, responses of cyanobacteria to these global changes are complex, if not contradictory. We hypothesized that absolute and relative biovolumes of cyanobacteria (both total and specific genera) are increasing in Swedish nutrient-poor lakes and that these increases are associated with global changes. We tested these hypotheses using data from 28 nutrient-poor Swedish lakes over 16 years (1998–2013). Increases in cyanobacteria relative biovolume were identified in 21\\% of the study sites, primarily in the southeastern region of Sweden, and were composed mostly of increases from three specific genera: Merismopedia, Chroococcus and Dolichospermum. Taxon-specific changes were related to different environmental stressors; that is, increased surface water temperature favoured higher Merismopedia relative biovolume in low pH lakes with high nitrogen to phosphorus ratios, whereas acidification recovery was statistically related to increased relative biovolumes of Chroococcus and Dolichospermum. In addition, enhanced dissolved organic matter loads were identified as potential determinants of Chroococcus suppression and Dolichospermum promotion. Our findings highlight that specific genera of cyanobacteria benefit from different environmental changes. Our ability to predict the risk of cyanobacteria prevalence requires consideration of the environmental condition of a lake and the sensitivities of the cyanobacteria genera within the lake. Regional patterns may emerge due to spatial autocorrelations within and among lake history, rates and direction of environmental change and the niche space occupied by specific cyanobacteria.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Freeman, Erika C. and Creed, Irena F. and Jones, Blake and Bergström, Ann-Kristin},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15189},\n\tkeywords = {\\#nosource, Climate change, Sweden, acidification recovery, browning, climate change, cyanobacteria, northern lakes},\n\tpages = {4966--4987},\n}\n\n\n\n\n\n The interacting effects of global changes—including increased temperature, altered precipitation, reduced acidification and increased dissolved organic matter loads to lakes—are anticipated to create favourable environmental conditions for cyanobacteria in northern lakes. However, responses of cyanobacteria to these global changes are complex, if not contradictory. We hypothesized that absolute and relative biovolumes of cyanobacteria (both total and specific genera) are increasing in Swedish nutrient-poor lakes and that these increases are associated with global changes. We tested these hypotheses using data from 28 nutrient-poor Swedish lakes over 16 years (1998–2013). Increases in cyanobacteria relative biovolume were identified in 21% of the study sites, primarily in the southeastern region of Sweden, and were composed mostly of increases from three specific genera: Merismopedia, Chroococcus and Dolichospermum. Taxon-specific changes were related to different environmental stressors; that is, increased surface water temperature favoured higher Merismopedia relative biovolume in low pH lakes with high nitrogen to phosphorus ratios, whereas acidification recovery was statistically related to increased relative biovolumes of Chroococcus and Dolichospermum. In addition, enhanced dissolved organic matter loads were identified as potential determinants of Chroococcus suppression and Dolichospermum promotion. Our findings highlight that specific genera of cyanobacteria benefit from different environmental changes. Our ability to predict the risk of cyanobacteria prevalence requires consideration of the environmental condition of a lake and the sensitivities of the cyanobacteria genera within the lake. Regional patterns may emerge due to spatial autocorrelations within and among lake history, rates and direction of environmental change and the niche space occupied by specific cyanobacteria.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dissolved organic matter regulates nutrient limitation and growth of benthic algae in northern lakes through interacting effects on nutrient and light availability.\n \n \n \n \n\n\n \n Fork, M. L.; Karlsson, J.; and Sponseller, R. A.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 5(6): 417–424. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10166\n\n\n\n
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\n\n\n@article{fork_dissolved_2020,\n\ttitle = {Dissolved organic matter regulates nutrient limitation and growth of benthic algae in northern lakes through interacting effects on nutrient and light availability},\n\tvolume = {5},\n\tcopyright = {© 2020 The Authors. Limnology and Oceanography Letters published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {2378-2242},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10166},\n\tdoi = {10.1002/lol2.10166},\n\tabstract = {Widespread increases in dissolved organic matter (DOM) concentration across northern lakes can alter rates of primary production by increasing nutrient availability and decreasing light availability. These dual effects of DOM generate a unimodal relationship in pelagic primary production and primary producer biomass among lakes over a gradient of DOM concentration. However, the responses of benthic algae to variation in DOM loading are less clear because of their potential to access sediment nutrients. We tested algal production and nutrient limitation along a DOM gradient in northern Sweden. Without added nutrients, benthic algal production showed a unimodal relationship with DOM, similar to reported pelagic responses. Nutrient addition revealed widespread nitrogen limitation, with decreasing severity in lakes with higher DOM. Because the majority of northern Swedish lakes currently fall below the inflection point in this unimodal relationship, moderate increases in DOM have the potential to increase benthic primary production, particularly for epilithic algae.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Fork, Megan L. and Karlsson, Jan and Sponseller, Ryan A.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10166},\n\tkeywords = {\\#nosource},\n\tpages = {417--424},\n}\n\n\n\n\n\n Widespread increases in dissolved organic matter (DOM) concentration across northern lakes can alter rates of primary production by increasing nutrient availability and decreasing light availability. These dual effects of DOM generate a unimodal relationship in pelagic primary production and primary producer biomass among lakes over a gradient of DOM concentration. However, the responses of benthic algae to variation in DOM loading are less clear because of their potential to access sediment nutrients. We tested algal production and nutrient limitation along a DOM gradient in northern Sweden. Without added nutrients, benthic algal production showed a unimodal relationship with DOM, similar to reported pelagic responses. Nutrient addition revealed widespread nitrogen limitation, with decreasing severity in lakes with higher DOM. Because the majority of northern Swedish lakes currently fall below the inflection point in this unimodal relationship, moderate increases in DOM have the potential to increase benthic primary production, particularly for epilithic algae.\n
\n\n\n\n \n\n \n \n \n \n \n \n Relative Importance of Climate, Soil and Plant Functional Traits During the Early Decomposition Stage of Standardized Litter.\n \n \n \n \n\n\n \n Fanin, N.; Bezaud, S.; Sarneel, J. M.; Cecchini, S.; Nicolas, M.; and Augusto, L.\n\n\n \n\n\n\n Ecosystems, 23(5): 1004–1018. August 2020.\n \n\n\n\n
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\n\n\n@article{fanin_relative_2020,\n\ttitle = {Relative {Importance} of {Climate}, {Soil} and {Plant} {Functional} {Traits} {During} the {Early} {Decomposition} {Stage} of {Standardized} {Litter}},\n\tvolume = {23},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-019-00452-z},\n\tdoi = {10.1007/s10021-019-00452-z},\n\tabstract = {Climatic factors have long been considered predominant in controlling decomposition rates at large spatial scales. However, recent research suggests that edaphic factors and plant functional traits may play a more important role than previously expected. In this study, we investigated how biotic and abiotic factors interacted with litter quality by analyzing decomposition rates for two forms of standardized litter substitutes: green tea (high-quality litter) and red tea (low-quality litter). We placed 1188 teabags at two different positions (forest floor and 8 cm deep) across 99 forest sites in France and measured 46 potential drivers at each site. We found that high-quality litter decomposition was strongly related to climatic factors, whereas low-quality litter decomposition was strongly related to edaphic factors and the identity of the dominant tree species in the stand. This indicates that the relative importance of climate, soil and plant functional traits in the litter decomposition process depends on litter quality, which was the predominant factor controlling decomposition rate in this experiment. We also found that burying litter increased decomposition rates, and that this effect was more important for green tea in drier environments. This suggests that changes in position (surface vs. buried) at the plot scale may be as important as the role of macroclimate on decomposition rates because of varying water availability along the soil profile. Acknowledging that the effect of climate on decomposition depends on litter quality and that the macroclimate is not necessarily the predominant factor at large spatial scales is the first step toward identifying the factors regulating decomposition rates from the local scale to the global scale.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-26},\n\tjournal = {Ecosystems},\n\tauthor = {Fanin, Nicolas and Bezaud, Sophie and Sarneel, Judith M. and Cecchini, Sébastien and Nicolas, Manuel and Augusto, Laurent},\n\tmonth = aug,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Carbon turnover, climate, decomposition, nutrient cycling, plant traits, soil depth, soil parent material, soil properties, tea bag index},\n\tpages = {1004--1018},\n}\n\n\n\n\n\n Climatic factors have long been considered predominant in controlling decomposition rates at large spatial scales. However, recent research suggests that edaphic factors and plant functional traits may play a more important role than previously expected. In this study, we investigated how biotic and abiotic factors interacted with litter quality by analyzing decomposition rates for two forms of standardized litter substitutes: green tea (high-quality litter) and red tea (low-quality litter). We placed 1188 teabags at two different positions (forest floor and 8 cm deep) across 99 forest sites in France and measured 46 potential drivers at each site. We found that high-quality litter decomposition was strongly related to climatic factors, whereas low-quality litter decomposition was strongly related to edaphic factors and the identity of the dominant tree species in the stand. This indicates that the relative importance of climate, soil and plant functional traits in the litter decomposition process depends on litter quality, which was the predominant factor controlling decomposition rate in this experiment. We also found that burying litter increased decomposition rates, and that this effect was more important for green tea in drier environments. This suggests that changes in position (surface vs. buried) at the plot scale may be as important as the role of macroclimate on decomposition rates because of varying water availability along the soil profile. Acknowledging that the effect of climate on decomposition depends on litter quality and that the macroclimate is not necessarily the predominant factor at large spatial scales is the first step toward identifying the factors regulating decomposition rates from the local scale to the global scale.\n
\n\n\n\n \n\n \n \n \n \n \n \n Documenting lemming population change in the Arctic: Can we detect trends?.\n \n \n \n \n\n\n \n Ehrich, D.; Schmidt, N. M.; Gauthier, G.; Alisauskas, R.; Angerbjörn, A.; Clark, K.; Ecke, F.; Eide, N. E.; Framstad, E.; Frandsen, J.; Franke, A.; Gilg, O.; Giroux, M.; Henttonen, H.; Hörnfeldt, B.; Ims, R. A.; Kataev, G. D.; Kharitonov, S. P.; Killengreen, S. T.; Krebs, C. J.; Lanctot, R. B.; Lecomte, N.; Menyushina, I. E.; Morris, D. W.; Morrisson, G.; Oksanen, L.; Oksanen, T.; Olofsson, J.; Pokrovsky, I. G.; Popov, I. Y.; Reid, D.; Roth, J. D.; Saalfeld, S. T.; Samelius, G.; Sittler, B.; Sleptsov, S. M.; Smith, P. A.; Sokolov, A. A.; Sokolova, N. A.; Soloviev, M. Y.; and Solovyeva, D. V.\n\n\n \n\n\n\n Ambio, 49(3): 786–800. March 2020.\n \n\n\n\n
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\n\n\n@article{ehrich_documenting_2020,\n\ttitle = {Documenting lemming population change in the {Arctic}: {Can} we detect trends?},\n\tvolume = {49},\n\tissn = {1654-7209},\n\tshorttitle = {Documenting lemming population change in the {Arctic}},\n\turl = {https://doi.org/10.1007/s13280-019-01198-7},\n\tdoi = {10.1007/s13280-019-01198-7},\n\tabstract = {Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Ambio},\n\tauthor = {Ehrich, Dorothée and Schmidt, Niels M. and Gauthier, Gilles and Alisauskas, Ray and Angerbjörn, Anders and Clark, Karin and Ecke, Frauke and Eide, Nina E. and Framstad, Erik and Frandsen, Jay and Franke, Alastair and Gilg, Olivier and Giroux, Marie-Andrée and Henttonen, Heikki and Hörnfeldt, Birger and Ims, Rolf A. and Kataev, Gennadiy D. and Kharitonov, Sergey P. and Killengreen, Siw T. and Krebs, Charles J. and Lanctot, Richard B. and Lecomte, Nicolas and Menyushina, Irina E. and Morris, Douglas W. and Morrisson, Guy and Oksanen, Lauri and Oksanen, Tarja and Olofsson, Johan and Pokrovsky, Ivan G. and Popov, Igor Yu. and Reid, Donald and Roth, James D. and Saalfeld, Sarah T. and Samelius, Gustaf and Sittler, Benoit and Sleptsov, Sergey M. and Smith, Paul A. and Sokolov, Aleksandr A. and Sokolova, Natalya A. and Soloviev, Mikhail Y. and Solovyeva, Diana V.},\n\tmonth = mar,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Arctic, Dicrostonyx, Lemmus, Population monitoring, Small rodent, Temporal trends},\n\tpages = {786--800},\n}\n\n\n\n\n\n Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.\n
\n\n\n\n \n\n \n \n \n \n \n \n Patterns of Spring/Summer Open-Water Metabolism Across Boreal Lakes.\n \n \n \n \n\n\n \n Bogard, M. J.; St-Gelais, N. F.; Vachon, D.; and del Giorgio, P. A.\n\n\n \n\n\n\n Ecosystems, 23(8): 1581–1597. December 2020.\n \n\n\n\n
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\n\n\n@article{bogard_patterns_2020,\n\ttitle = {Patterns of {Spring}/{Summer} {Open}-{Water} {Metabolism} {Across} {Boreal} {Lakes}},\n\tvolume = {23},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-020-00487-7},\n\tdoi = {10.1007/s10021-020-00487-7},\n\tabstract = {Northern regions host the greatest density of surface water globally, but knowledge of lake metabolism in this vast yet remote landscape is limited. Here, we used an oxygen stable isotope approach to quantify patterns and drivers of surface layer metabolism in lakes throughout an approximately 106 km2 tract of boreal Canada. Ecosystem gross primary production (GPP) and respiration rates (R) were much higher than previously assumed for spring and summer months. Both rates were strongly linked to nitrogen (N) concentrations, not light availability, despite earlier work showing community-level light effects. Net ecosystem production (NEP = GPP − R) was negative for most lakes. Hierarchical modeling revealed that although NEP is strongly stabilized via similar effects of N on both GPP and R, NEP decreases with increasing dissolved organic carbon (DOC). These interactive controls on NEP were not predictable from bivariate regressions linking NEP to physical, chemical or habitat-specific drivers. In contrast to expectations, NEP was higher in warmer waters due to increased temperature dependency of GPP, not R. Temperature and DOC content had opposing effects on NEP in all but the most dystrophic lakes, possibly implying a muted response of metabolic balances to future shifts in both regional climate and OC delivery.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2024-03-26},\n\tjournal = {Ecosystems},\n\tauthor = {Bogard, Matthew J. and St-Gelais, Nicolas F. and Vachon, Dominic and del Giorgio, Paul A.},\n\tmonth = dec,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Boreal lake, Catchment, Climate, Food web, Landscape, Metabolism, Net ecosystem production, Primary production, Respiration},\n\tpages = {1581--1597},\n}\n\n\n\n\n\n Northern regions host the greatest density of surface water globally, but knowledge of lake metabolism in this vast yet remote landscape is limited. Here, we used an oxygen stable isotope approach to quantify patterns and drivers of surface layer metabolism in lakes throughout an approximately 106 km2 tract of boreal Canada. Ecosystem gross primary production (GPP) and respiration rates (R) were much higher than previously assumed for spring and summer months. Both rates were strongly linked to nitrogen (N) concentrations, not light availability, despite earlier work showing community-level light effects. Net ecosystem production (NEP = GPP − R) was negative for most lakes. Hierarchical modeling revealed that although NEP is strongly stabilized via similar effects of N on both GPP and R, NEP decreases with increasing dissolved organic carbon (DOC). These interactive controls on NEP were not predictable from bivariate regressions linking NEP to physical, chemical or habitat-specific drivers. In contrast to expectations, NEP was higher in warmer waters due to increased temperature dependency of GPP, not R. Temperature and DOC content had opposing effects on NEP in all but the most dystrophic lakes, possibly implying a muted response of metabolic balances to future shifts in both regional climate and OC delivery.\n
\n\n\n\n \n\n \n \n \n \n \n \n Invasive earthworms unlock arctic plant nitrogen limitation.\n \n \n \n \n\n\n \n Blume-Werry, G.; Krab, E. J.; Olofsson, J.; Sundqvist, M. K.; Väisänen, M.; and Klaminder, J.\n\n\n \n\n\n\n Nature Communications, 11(1): 1–10. April 2020.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{blume-werry_invasive_2020,\n\ttitle = {Invasive earthworms unlock arctic plant nitrogen limitation},\n\tvolume = {11},\n\tcopyright = {2020 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-020-15568-3},\n\tdoi = {10.1038/s41467-020-15568-3},\n\tabstract = {Arctic plant growth is predominantly nitrogen limited, where the slow nitrogen turnover in the soil is commonly attributed to the cold arctic climate. Here the authors show that the arctic plant-soil nitrogen cycling is also constrained by the lack of larger detritivores like earthworms.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-04-23},\n\tjournal = {Nature Communications},\n\tauthor = {Blume-Werry, Gesche and Krab, Eveline J. and Olofsson, Johan and Sundqvist, Maja K. and Väisänen, Maria and Klaminder, Jonatan},\n\tmonth = apr,\n\tyear = {2020},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {1--10},\n}\n\n\n\n\n\n\n\n\n\n Arctic plant growth is predominantly nitrogen limited, where the slow nitrogen turnover in the soil is commonly attributed to the cold arctic climate. Here the authors show that the arctic plant-soil nitrogen cycling is also constrained by the lack of larger detritivores like earthworms.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dissolved organic matter biodegradation along a hydrological continuum in permafrost peatlands.\n \n \n \n \n\n\n \n Payandi-Rolland, D.; Shirokova, L.; Tesfa, M.; Bénézeth, P.; Lim, A.; Kuzmina, D.; Karlsson, J.; Giesler, R.; and Pokrovsky, O.\n\n\n \n\n\n\n Science of The Total Environment, 749: 141463. December 2020.\n \n\n\n\n
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\n\n\n@article{payandi-rolland_dissolved_2020,\n\ttitle = {Dissolved organic matter biodegradation along a hydrological continuum in permafrost peatlands},\n\tvolume = {749},\n\tissn = {0048-9697},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969720349925},\n\tdoi = {10.1016/j.scitotenv.2020.141463},\n\tabstract = {Arctic regions contain large amounts of organic carbon (OC) trapped in soil and wetland permafrost. With climate warming, part of this OC is released to aquatic systems and degraded by microorganisms, thus resulting in positive feedback due to carbon (C) emission. In wetland areas, water bodies are spatially heterogenic and separated by landscape position and water residence time. This represents a hydrological continuum, from depressions, smaller water bodies and lakes to the receiving streams and rivers. Yet, the effect of this heterogeneity on the OC release from the soil and its processing in waters is largely unknown and not accounted for in C cycle models of Arctic regions. Here we investigated the dissolved OC (DOC) biodegradation of aquatic systems along a hydrological continuum located in two discontinuous permafrost sites: in western Siberia and northern Sweden. The biodegradable dissolved OC (BDOC15; \\% DOC lost relative to the initial DOC concentration after 15 days incubation at 20 °C) ranged from 0 to 20\\% for small water bodies located at the beginning of the continuum (soil solutions, small ponds, fen and lakes) and from 10 to 20\\% for streams and rivers. While the BDOC15 increased, the removal rate of DOC decreased along the hydrological continuum. The potential maximum CO2 production from DOC biodegradation was estimated to account for only a small part of in-situ CO2 emissions measured in peatland aquatic systems of northern Sweden and western Siberia. This suggests that other sources, such as sediment respiration and soil input, largely contribute to CO2 emissions from small surface waters of permafrost peatlands. Our results highlight the need to account for large heterogeneity of dissolved OC concentration and biodegradability in order to quantify C cycling in arctic water bodies susceptible to permafrost thaw.},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Payandi-Rolland, D. and Shirokova, L.S. and Tesfa, M. and Bénézeth, P. and Lim, A.G. and Kuzmina, D. and Karlsson, J. and Giesler, R. and Pokrovsky, O.S.},\n\tmonth = dec,\n\tyear = {2020},\n\tkeywords = {Carbon dioxide emission, Low molecular weight organic acids, River, Stream, Supra-permafrost water, Thermokarst lake},\n\tpages = {141463},\n}\n\n\n\n\n\n Arctic regions contain large amounts of organic carbon (OC) trapped in soil and wetland permafrost. With climate warming, part of this OC is released to aquatic systems and degraded by microorganisms, thus resulting in positive feedback due to carbon (C) emission. In wetland areas, water bodies are spatially heterogenic and separated by landscape position and water residence time. This represents a hydrological continuum, from depressions, smaller water bodies and lakes to the receiving streams and rivers. Yet, the effect of this heterogeneity on the OC release from the soil and its processing in waters is largely unknown and not accounted for in C cycle models of Arctic regions. Here we investigated the dissolved OC (DOC) biodegradation of aquatic systems along a hydrological continuum located in two discontinuous permafrost sites: in western Siberia and northern Sweden. The biodegradable dissolved OC (BDOC15; % DOC lost relative to the initial DOC concentration after 15 days incubation at 20 °C) ranged from 0 to 20% for small water bodies located at the beginning of the continuum (soil solutions, small ponds, fen and lakes) and from 10 to 20% for streams and rivers. While the BDOC15 increased, the removal rate of DOC decreased along the hydrological continuum. The potential maximum CO2 production from DOC biodegradation was estimated to account for only a small part of in-situ CO2 emissions measured in peatland aquatic systems of northern Sweden and western Siberia. This suggests that other sources, such as sediment respiration and soil input, largely contribute to CO2 emissions from small surface waters of permafrost peatlands. Our results highlight the need to account for large heterogeneity of dissolved OC concentration and biodegradability in order to quantify C cycling in arctic water bodies susceptible to permafrost thaw.\n
\n\n\n\n \n\n \n \n \n \n \n \n Meshes in mesocosms control solute and biota exchange in soils: A step towards disentangling (a)biotic impacts on the fate of thawing permafrost.\n \n \n \n \n\n\n \n Väisänen, M.; Krab, E. J.; Monteux, S.; Teuber, L. M.; Gavazov, K.; Weedon, J. T.; Keuper, F.; and Dorrepaal, E.\n\n\n \n\n\n\n Applied Soil Ecology, 151: 103537. July 2020.\n \n\n\n\n
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\n\n\n@article{vaisanen_meshes_2020,\n\ttitle = {Meshes in mesocosms control solute and biota exchange in soils: {A} step towards disentangling (a)biotic impacts on the fate of thawing permafrost},\n\tvolume = {151},\n\tissn = {0929-1393},\n\tshorttitle = {Meshes in mesocosms control solute and biota exchange in soils},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0929139319307206},\n\tdoi = {10.1016/j.apsoil.2020.103537},\n\tabstract = {Environmental changes feedback to climate through their impact on soil functions such as carbon (C) and nutrient sequestration. Abiotic conditions and the interactions between above- and belowground biota drive soil responses to environmental change but these (a)biotic interactions are challenging to study. Nonetheless, better understanding of these interactions would improve predictions of future soil functioning and the soil-climate feedback and, in this context, permafrost soils are of particular interest due to their vast soil C-stores. We need new tools to isolate abiotic (microclimate, chemistry) and biotic (roots, fauna, microorganisms) components and to identify their respective roles in soil processes. We developed a new experimental setup, in which we mimic thermokarst (permafrost thaw-induced soil subsidence) by fitting thawed permafrost and vegetated active layer sods side by side into mesocosms deployed in a subarctic tundra over two growing seasons. In each mesocosm, the two sods were separated from each other by barriers with different mesh sizes to allow varying degrees of physical connection and, consequently, (a)biotic exchange between active layer and permafrost. We demonstrate that our mesh-approach succeeded in controlling 1) lateral exchange of solutes between the two soil types, 2) colonization of permafrost by microbes but not by soil fauna, and 3) ingrowth of roots into permafrost. In particular, experimental thermokarst induced a {\\textasciitilde}60\\% decline in permafrost nitrogen (N) content, a shift in soil bacteria and a rapid buildup of root biomass (+33.2 g roots m−2 soil). This indicates that cascading plant-soil-microbe linkages are at the heart of biogeochemical cycling in thermokarst events. We propose that this novel setup can be used to explore the effects of (a)biotic ecosystem components on focal biogeochemical processes in permafrost soils and beyond.},\n\tlanguage = {en},\n\turldate = {2020-04-23},\n\tjournal = {Applied Soil Ecology},\n\tauthor = {Väisänen, Maria and Krab, Eveline J. and Monteux, Sylvain and Teuber, Laurenz M. and Gavazov, Konstantin and Weedon, James T. and Keuper, Frida and Dorrepaal, Ellen},\n\tmonth = jul,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Bacterial community, Faunal inoculation, Field incubation, Lateral soil connection, Nitrogen, Root},\n\tpages = {103537},\n}\n\n\n\n\n\n Environmental changes feedback to climate through their impact on soil functions such as carbon (C) and nutrient sequestration. Abiotic conditions and the interactions between above- and belowground biota drive soil responses to environmental change but these (a)biotic interactions are challenging to study. Nonetheless, better understanding of these interactions would improve predictions of future soil functioning and the soil-climate feedback and, in this context, permafrost soils are of particular interest due to their vast soil C-stores. We need new tools to isolate abiotic (microclimate, chemistry) and biotic (roots, fauna, microorganisms) components and to identify their respective roles in soil processes. We developed a new experimental setup, in which we mimic thermokarst (permafrost thaw-induced soil subsidence) by fitting thawed permafrost and vegetated active layer sods side by side into mesocosms deployed in a subarctic tundra over two growing seasons. In each mesocosm, the two sods were separated from each other by barriers with different mesh sizes to allow varying degrees of physical connection and, consequently, (a)biotic exchange between active layer and permafrost. We demonstrate that our mesh-approach succeeded in controlling 1) lateral exchange of solutes between the two soil types, 2) colonization of permafrost by microbes but not by soil fauna, and 3) ingrowth of roots into permafrost. In particular, experimental thermokarst induced a ~60% decline in permafrost nitrogen (N) content, a shift in soil bacteria and a rapid buildup of root biomass (+33.2 g roots m−2 soil). This indicates that cascading plant-soil-microbe linkages are at the heart of biogeochemical cycling in thermokarst events. We propose that this novel setup can be used to explore the effects of (a)biotic ecosystem components on focal biogeochemical processes in permafrost soils and beyond.\n
\n\n\n\n \n\n \n \n \n \n \n The Transition From Stochastic to Deterministic Bacterial Community Assembly During Permafrost Thaw Succession.\n \n \n \n\n\n \n Doherty, S.; Barbato, R.; Grandy, A.; Thomas, W.; Monteux, S.; Dorrepaal, E.; Johansson, M.; and Ernakovich, J.\n\n\n \n\n\n\n Frontiers in Microbiology, 11: 596589. November 2020.\n \n\n\n\n
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\n\n\n@article{doherty_transition_2020,\n\ttitle = {The {Transition} {From} {Stochastic} to {Deterministic} {Bacterial} {Community} {Assembly} {During} {Permafrost} {Thaw} {Succession}},\n\tvolume = {11},\n\tdoi = {10.3389/fmicb.2020.596589},\n\tabstract = {The Northern high latitudes are warming twice as fast as the global average, and permafrost has become vulnerable to thaw. Changes to the environment during thaw leads to shifts in microbial communities and their associated functions, such as greenhouse gas emissions. Understanding the ecological processes that structure the identity and abundance (i.e., assembly) of pre- and post-thaw communities may improve predictions of the functional outcomes of permafrost thaw. We characterized microbial community assembly during permafrost thaw using in situ observations and a laboratory incubation of soils from the Storflaket Mire in Abisko, Sweden, where permafrost thaw has occurred over the past decade. In situ observations indicated that bacterial community assembly was driven by randomness (i.e., stochastic processes) immediately after thaw with drift and dispersal limitation being the dominant processes. As post-thaw succession progressed, environmentally driven (i.e., deterministic) processes became increasingly important in structuring microbial communities where homogenizing selection was the only process structuring upper active layer soils. Furthermore, laboratory-induced thaw reflected assembly dynamics immediately after thaw indicated by an increase in drift, but did not capture the long-term effects of permafrost thaw on microbial community dynamics. Our results did not reflect a link between assembly dynamics and carbon emissions, likely because respiration is the product of many processes in microbial communities. Identification of dominant microbial community assembly processes has the potential to improve our understanding of the ecological impact of permafrost thaw and the permafrost–climate feedback.},\n\tjournal = {Frontiers in Microbiology},\n\tauthor = {Doherty, Stacey and Barbato, Robyn and Grandy, A. and Thomas, William and Monteux, Sylvain and Dorrepaal, Ellen and Johansson, Margareta and Ernakovich, Jessica},\n\tmonth = nov,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {596589},\n}\n\n\n\n\n\n The Northern high latitudes are warming twice as fast as the global average, and permafrost has become vulnerable to thaw. Changes to the environment during thaw leads to shifts in microbial communities and their associated functions, such as greenhouse gas emissions. Understanding the ecological processes that structure the identity and abundance (i.e., assembly) of pre- and post-thaw communities may improve predictions of the functional outcomes of permafrost thaw. We characterized microbial community assembly during permafrost thaw using in situ observations and a laboratory incubation of soils from the Storflaket Mire in Abisko, Sweden, where permafrost thaw has occurred over the past decade. In situ observations indicated that bacterial community assembly was driven by randomness (i.e., stochastic processes) immediately after thaw with drift and dispersal limitation being the dominant processes. As post-thaw succession progressed, environmentally driven (i.e., deterministic) processes became increasingly important in structuring microbial communities where homogenizing selection was the only process structuring upper active layer soils. Furthermore, laboratory-induced thaw reflected assembly dynamics immediately after thaw indicated by an increase in drift, but did not capture the long-term effects of permafrost thaw on microbial community dynamics. Our results did not reflect a link between assembly dynamics and carbon emissions, likely because respiration is the product of many processes in microbial communities. Identification of dominant microbial community assembly processes has the potential to improve our understanding of the ecological impact of permafrost thaw and the permafrost–climate feedback.\n
\n\n\n\n \n\n \n \n \n \n \n Biotic and environmental drivers of plant microbiomes across a permafrost thaw gradient.\n \n \n \n\n\n \n Hough, M.; McClure, A.; Bolduc, B.; Dorrepaal, E.; Saleska, S.; Klepac-Ceraj, V.; and Rich, V.\n\n\n \n\n\n\n Frontiers in Microbiology, 11: 796. 2020.\n Publisher: Frontiers Media SA\n\n\n\n
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\n\n\n\n@article{hough_biotic_2020,\n\ttitle = {Biotic and environmental drivers of plant microbiomes across a permafrost thaw gradient},\n\tvolume = {11},\n\tdoi = {10.3389/fmicb.2020.00796},\n\tjournal = {Frontiers in Microbiology},\n\tauthor = {Hough, Moira and McClure, Amelia and Bolduc, Benjamin and Dorrepaal, Ellen and Saleska, Scott and Klepac-Ceraj, Vanja and Rich, Virginia},\n\tyear = {2020},\n\tnote = {Publisher: Frontiers Media SA},\n\tkeywords = {\\#nosource},\n\tpages = {796},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n The IsoGenie database: An interdisciplinary data management solution for ecosystems biology and environmental research.\n \n \n \n\n\n \n Bolduc, B.; Hodgkins, S.; Varner, R.; Crill, P.; Mccalley, C.; Chanton, J.; Tyson, G.; Riley, W.; Palace, M.; Duhaime, M.; Hough, M.; Saleska, S.; Sullivan, M.; Rich, V.; Zayed, A.; Cory, A.; Mcclure, A.; Garnello, A.; Perry, A.; and Cooper, W.\n\n\n \n\n\n\n PeerJ, 8: e9467. August 2020.\n \n\n\n\n
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\n\n\n@article{bolduc_isogenie_2020,\n\ttitle = {The {IsoGenie} database: {An} interdisciplinary data management solution for ecosystems biology and environmental research},\n\tvolume = {8},\n\tdoi = {10.7717/peerj.9467},\n\tabstract = {Modern microbial and ecosystem sciences require diverse interdisciplinary teams that are often challenged in “speaking” to one another due to different languages and data product types. Here we introduce the IsoGenie Database (IsoGenieDB; https://isogenie-db.asc.ohio-state.edu/ ), a de novo developed data management and exploration platform, as a solution to this challenge of accurately representing and integrating heterogenous environmental and microbial data across ecosystem scales. The IsoGenieDB is a public and private data infrastructure designed to store and query data generated by the IsoGenie Project, a {\\textasciitilde}10 year DOE-funded project focused on discovering ecosystem climate feedbacks in a thawing permafrost landscape. The IsoGenieDB provides (i) a platform for IsoGenie Project members to explore the project’s interdisciplinary datasets across scales through the inherent relationships among data entities, (ii) a framework to consolidate and harmonize the datasets needed by the team’s modelers, and (iii) a public venue that leverages the same spatially explicit, disciplinarily integrated data structure to share published datasets. The IsoGenieDB is also being expanded to cover the NASA-funded Archaea to Atmosphere (A2A) project, which scales the findings of IsoGenie to a broader suite of Arctic peatlands, via the umbrella A2A Database (A2A-DB). The IsoGenieDB’s expandability and flexible architecture allow it to serve as an example ecosystems database.},\n\tjournal = {PeerJ},\n\tauthor = {Bolduc, Benjamin and Hodgkins, Suzanne and Varner, Ruth and Crill, Patrick and Mccalley, Carmody and Chanton, Jeffrey and Tyson, Gene and Riley, William and Palace, Michael and Duhaime, Melissa and Hough, Moira and Saleska, Scott and Sullivan, Matthew and Rich, Virginia and Zayed, Ahmed and Cory, Alex and Mcclure, Amelia and Garnello, Anthony and Perry, Apryl and Cooper, William},\n\tmonth = aug,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {e9467},\n}\n\n\n\n\n\n Modern microbial and ecosystem sciences require diverse interdisciplinary teams that are often challenged in “speaking” to one another due to different languages and data product types. Here we introduce the IsoGenie Database (IsoGenieDB; https://isogenie-db.asc.ohio-state.edu/ ), a de novo developed data management and exploration platform, as a solution to this challenge of accurately representing and integrating heterogenous environmental and microbial data across ecosystem scales. The IsoGenieDB is a public and private data infrastructure designed to store and query data generated by the IsoGenie Project, a ~10 year DOE-funded project focused on discovering ecosystem climate feedbacks in a thawing permafrost landscape. The IsoGenieDB provides (i) a platform for IsoGenie Project members to explore the project’s interdisciplinary datasets across scales through the inherent relationships among data entities, (ii) a framework to consolidate and harmonize the datasets needed by the team’s modelers, and (iii) a public venue that leverages the same spatially explicit, disciplinarily integrated data structure to share published datasets. The IsoGenieDB is also being expanded to cover the NASA-funded Archaea to Atmosphere (A2A) project, which scales the findings of IsoGenie to a broader suite of Arctic peatlands, via the umbrella A2A Database (A2A-DB). The IsoGenieDB’s expandability and flexible architecture allow it to serve as an example ecosystems database.\n
\n\n\n\n \n\n \n \n \n \n \n \n Mosses modify effects of warmer and wetter conditions on tree seedlings at the alpine treeline.\n \n \n \n \n\n\n \n Lett, S.; Teuber, L. M.; Krab, E. J.; Michelsen, A.; Olofsson, J.; Nilsson, M.; Wardle, D. A.; and Dorrepaal, E.\n\n\n \n\n\n\n Global Change Biology, 26(10): 5754–5766. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15256\n\n\n\n
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\n\n\n@article{lett_mosses_2020,\n\ttitle = {Mosses modify effects of warmer and wetter conditions on tree seedlings at the alpine treeline},\n\tvolume = {26},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15256},\n\tdoi = {10.1111/gcb.15256},\n\tabstract = {Climate warming enables tree seedling establishment beyond the current alpine treeline, but to achieve this, seedlings have to establish within existing tundra vegetation. In tundra, mosses are a prominent feature, known to regulate soil temperature and moisture through their physical structure and associated water retention capacity. Moss presence and species identity might therefore modify the impact of increases in temperature and precipitation on tree seedling establishment at the arctic-alpine treeline. We followed Betula pubescens and Pinus sylvestris seedling survival and growth during three growing seasons in the field. Tree seedlings were transplanted along a natural precipitation gradient at the subarctic-alpine treeline in northern Sweden, into plots dominated by each of three common moss species and exposed to combinations of moss removal and experimental warming by open-top chambers (OTCs). Independent of climate, the presence of feather moss, but not Sphagnum, strongly supressed survival of both tree species. Positive effects of warming and precipitation on survival and growth of B. pubescens seedlings occurred in the absence of mosses and as expected, this was partly dependent on moss species. P. sylvestris survival was greatest at high precipitation, and this effect was more pronounced in Sphagnum than in feather moss plots irrespective of whether the mosses had been removed or not. Moss presence did not reduce the effects of OTCs on soil temperature. Mosses therefore modified seedling response to climate through other mechanisms, such as altered competition or nutrient availability. We conclude that both moss presence and species identity pose a strong control on seedling establishment at the alpine treeline, and that in some cases mosses weaken climate-change effects on seedling establishment. Changes in moss abundance and species composition therefore have the potential to hamper treeline expansion induced by climate warming.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2022-06-28},\n\tjournal = {Global Change Biology},\n\tauthor = {Lett, Signe and Teuber, Laurenz M. and Krab, Eveline J. and Michelsen, Anders and Olofsson, Johan and Nilsson, Marie-Charlotte and Wardle, David A. and Dorrepaal, Ellen},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15256},\n\tkeywords = {\\#nosource, Arctic, Betula pubescens, Pinus sylvestris, bryophytes, climate change, plant interactions, precipitation, treeline expansion},\n\tpages = {5754--5766},\n}\n\n\n\n\n\n Climate warming enables tree seedling establishment beyond the current alpine treeline, but to achieve this, seedlings have to establish within existing tundra vegetation. In tundra, mosses are a prominent feature, known to regulate soil temperature and moisture through their physical structure and associated water retention capacity. Moss presence and species identity might therefore modify the impact of increases in temperature and precipitation on tree seedling establishment at the arctic-alpine treeline. We followed Betula pubescens and Pinus sylvestris seedling survival and growth during three growing seasons in the field. Tree seedlings were transplanted along a natural precipitation gradient at the subarctic-alpine treeline in northern Sweden, into plots dominated by each of three common moss species and exposed to combinations of moss removal and experimental warming by open-top chambers (OTCs). Independent of climate, the presence of feather moss, but not Sphagnum, strongly supressed survival of both tree species. Positive effects of warming and precipitation on survival and growth of B. pubescens seedlings occurred in the absence of mosses and as expected, this was partly dependent on moss species. P. sylvestris survival was greatest at high precipitation, and this effect was more pronounced in Sphagnum than in feather moss plots irrespective of whether the mosses had been removed or not. Moss presence did not reduce the effects of OTCs on soil temperature. Mosses therefore modified seedling response to climate through other mechanisms, such as altered competition or nutrient availability. We conclude that both moss presence and species identity pose a strong control on seedling establishment at the alpine treeline, and that in some cases mosses weaken climate-change effects on seedling establishment. Changes in moss abundance and species composition therefore have the potential to hamper treeline expansion induced by climate warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Complexity revealed in the greening of the Arctic.\n \n \n \n \n\n\n \n Myers-Smith, I. H.; Kerby, J. T.; Phoenix, G. K.; Bjerke, J. W.; Epstein, H. E.; Assmann, J. J.; John, C.; Andreu-Hayles, L.; Angers-Blondin, S.; Beck, P. S. A.; Berner, L. T.; Bhatt, U. S.; Bjorkman, A. D.; Blok, D.; Bryn, A.; Christiansen, C. T.; Cornelissen, J. H. C.; Cunliffe, A. M.; Elmendorf, S. C.; Forbes, B. C.; Goetz, S. J.; Hollister, R. D.; de Jong, R.; Loranty, M. M.; Macias-Fauria, M.; Maseyk, K.; Normand, S.; Olofsson, J.; Parker, T. C.; Parmentier, F. W.; Post, E.; Schaepman-Strub, G.; Stordal, F.; Sullivan, P. F.; Thomas, H. J. D.; Tømmervik, H.; Treharne, R.; Tweedie, C. E.; Walker, D. A.; Wilmking, M.; and Wipf, S.\n\n\n \n\n\n\n Nature Climate Change, 10(2): 106–117. February 2020.\n Bandiera_abtest: a Cg_type: Nature Research Journals Number: 2 Primary_atype: Reviews Publisher: Nature Publishing Group Subject_term: Climate change;Climate-change ecology Subject_term_id: climate-change;climate-change-ecology\n\n\n\n
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\n\n\n@article{myers-smith_complexity_2020,\n\ttitle = {Complexity revealed in the greening of the {Arctic}},\n\tvolume = {10},\n\tcopyright = {2020 Springer Nature Limited},\n\tissn = {1758-6798},\n\turl = {http://www.nature.com/articles/s41558-019-0688-1},\n\tdoi = {10.1038/s41558-019-0688-1},\n\tabstract = {As the Arctic warms, vegetation is responding, and satellite measures indicate widespread greening at high latitudes. This ‘greening of the Arctic’ is among the world’s most important large-scale ecological responses to global climate change. However, a consensus is emerging that the underlying causes and future dynamics of so-called Arctic greening and browning trends are more complex, variable and inherently scale-dependent than previously thought. Here we summarize the complexities of observing and interpreting high-latitude greening to identify priorities for future research. Incorporating satellite and proximal remote sensing with in-situ data, while accounting for uncertainties and scale issues, will advance the study of past, present and future Arctic vegetation change.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2021-11-09},\n\tjournal = {Nature Climate Change},\n\tauthor = {Myers-Smith, Isla H. and Kerby, Jeffrey T. and Phoenix, Gareth K. and Bjerke, Jarle W. and Epstein, Howard E. and Assmann, Jakob J. and John, Christian and Andreu-Hayles, Laia and Angers-Blondin, Sandra and Beck, Pieter S. A. and Berner, Logan T. and Bhatt, Uma S. and Bjorkman, Anne D. and Blok, Daan and Bryn, Anders and Christiansen, Casper T. and Cornelissen, J. Hans C. and Cunliffe, Andrew M. and Elmendorf, Sarah C. and Forbes, Bruce C. and Goetz, Scott J. and Hollister, Robert D. and de Jong, Rogier and Loranty, Michael M. and Macias-Fauria, Marc and Maseyk, Kadmiel and Normand, Signe and Olofsson, Johan and Parker, Thomas C. and Parmentier, Frans-Jan W. and Post, Eric and Schaepman-Strub, Gabriela and Stordal, Frode and Sullivan, Patrick F. and Thomas, Haydn J. D. and Tømmervik, Hans and Treharne, Rachael and Tweedie, Craig E. and Walker, Donald A. and Wilmking, Martin and Wipf, Sonja},\n\tmonth = feb,\n\tyear = {2020},\n\tnote = {Bandiera\\_abtest: a\nCg\\_type: Nature Research Journals\nNumber: 2\nPrimary\\_atype: Reviews\nPublisher: Nature Publishing Group\nSubject\\_term: Climate change;Climate-change ecology\nSubject\\_term\\_id: climate-change;climate-change-ecology},\n\tkeywords = {\\#nosource, Climate change, Climate-change ecology},\n\tpages = {106--117},\n}\n\n\n\n\n\n As the Arctic warms, vegetation is responding, and satellite measures indicate widespread greening at high latitudes. This ‘greening of the Arctic’ is among the world’s most important large-scale ecological responses to global climate change. However, a consensus is emerging that the underlying causes and future dynamics of so-called Arctic greening and browning trends are more complex, variable and inherently scale-dependent than previously thought. Here we summarize the complexities of observing and interpreting high-latitude greening to identify priorities for future research. Incorporating satellite and proximal remote sensing with in-situ data, while accounting for uncertainties and scale issues, will advance the study of past, present and future Arctic vegetation change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Paired O$_{\\textrm{2}}$–CO$_{\\textrm{2}}$ measurements provide emergent insights into aquatic ecosystem function.\n \n \n \n \n\n\n \n Vachon, D.; Sadro, S.; Bogard, M. J.; Lapierre, J.; Baulch, H. M.; Rusak, J. A.; Denfeld, B. A.; Laas, A.; Klaus, M.; Karlsson, J.; Weyhenmeyer, G. A.; and Giorgio, P. A. d.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 5(4): 287–294. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10135\n\n\n\n
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\n\n\n@article{vachon_paired_2020,\n\ttitle = {Paired {O}$_{\\textrm{2}}$–{CO}$_{\\textrm{2}}$ measurements provide emergent insights into aquatic ecosystem function},\n\tvolume = {5},\n\tcopyright = {© 2019 The Authors. Limnology and Oceanography Letters published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {2378-2242},\n\turl = {http://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10135},\n\tdoi = {10.1002/lol2.10135},\n\tabstract = {Scientific Significance Statement Metabolic stoichiometry predicts that dissolved oxygen (O2) and carbon dioxide (CO2) in aquatic ecosystems should covary inversely; however, field observations often diverge from theoretical expectations. Here, we propose a suite of metrics describing this O2 and CO2 decoupling and introduce a conceptual framework for interpreting these metrics within aquatic ecosystems. Within this framework, we interpret cross-system patterns of high-frequency O2 and CO2 measurements in 11 northern lakes and extract emergent insights into the metabolic behavior and the simultaneous roles of chemical and physical forcing in shaping ecosystem processes. This approach leverages the power of high-frequency paired O2–CO2 measurements, and yields a novel, integrative aquatic system typology which can also be applicable more broadly to streams and rivers, wetlands and marine systems.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2021-01-19},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Vachon, Dominic and Sadro, Steven and Bogard, Matthew J. and Lapierre, Jean-François and Baulch, Helen M. and Rusak, James A. and Denfeld, Blaize A. and Laas, Alo and Klaus, Marcus and Karlsson, Jan and Weyhenmeyer, Gesa A. and Giorgio, Paul A. del},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10135},\n\tkeywords = {\\#nosource},\n\tpages = {287--294},\n}\n\n\n\n\n\n Scientific Significance Statement Metabolic stoichiometry predicts that dissolved oxygen (O2) and carbon dioxide (CO2) in aquatic ecosystems should covary inversely; however, field observations often diverge from theoretical expectations. Here, we propose a suite of metrics describing this O2 and CO2 decoupling and introduce a conceptual framework for interpreting these metrics within aquatic ecosystems. Within this framework, we interpret cross-system patterns of high-frequency O2 and CO2 measurements in 11 northern lakes and extract emergent insights into the metabolic behavior and the simultaneous roles of chemical and physical forcing in shaping ecosystem processes. This approach leverages the power of high-frequency paired O2–CO2 measurements, and yields a novel, integrative aquatic system typology which can also be applicable more broadly to streams and rivers, wetlands and marine systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Thaw Transitions and Redox Conditions Drive Methane Oxidation in a Permafrost Peatland.\n \n \n \n \n\n\n \n Perryman, C. R.; McCalley, C. K.; Malhotra, A.; Fahnestock, M. F.; Kashi, N. N.; Bryce, J. G.; Giesler, R.; and Varner, R. K.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 125(3): e2019JG005526. 2020.\n _eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JG005526\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{perryman_thaw_2020,\n\ttitle = {Thaw {Transitions} and {Redox} {Conditions} {Drive} {Methane} {Oxidation} in a {Permafrost} {Peatland}},\n\tvolume = {125},\n\tcopyright = {This article is protected by copyright. All rights reserved.},\n\tissn = {2169-8961},\n\turl = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005526},\n\tdoi = {10.1029/2019JG005526},\n\tabstract = {Permafrost peatlands are a significant source of methane (CH4) emissions to the atmosphere and could emit more CH4 with continued permafrost thaw. Aerobic methane-oxidizing bacteria may attenuate a substantial fraction of CH4 emissions in thawing permafrost peatlands; however, the impact of permafrost thaw on CH4 oxidation is uncertain. We measured potential CH4 oxidation rates (hereafter, CH4 oxidation) and their predictors using laboratory incubations and in situ porewater redox chemistry across a permafrost thaw gradient of eight thaw stages at Stordalen Mire, a permafrost peatland complex in northernmost Sweden. Methane oxidation rates increased across a gradient of permafrost thaw and differed in transitional thaw stages relative to end-member stages. Oxidation was consistently higher in submerged fens than in bogs or palsas across a range of CH4 concentrations. We also observed that CH4 oxidation increased with decreasing in situ redox potential and was highest in sites with lower redox potential (Eh {\\textless} 10 mV) and high water table. Our results suggest that redox potential can be used as an important predictor of CH4 oxidation, especially in thawed permafrost peatlands. Our results also highlight the importance of considering transitional thaw stages when characterizing landscape-scale CH4 dynamics, because these transitional areas have different rates and controls of CH4 oxidation relative to intact or completely thawed permafrost areas. As permafrost thaw increases the total area of semiwet and wet thaw stages in permafrost peatlands, CH4 oxidation represents an important control on CH4 emissions to the atmosphere.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-03-19},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Perryman, Clarice R. and McCalley, Carmody K. and Malhotra, Avni and Fahnestock, M. Florencia and Kashi, Natalie N. and Bryce, Julia G. and Giesler, Reiner and Varner, Ruth K.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JG005526},\n\tkeywords = {\\#nosource, methane, methanotrophs, peatland, permafrost, redox},\n\tpages = {e2019JG005526},\n}\n\n\n\n\n\n Permafrost peatlands are a significant source of methane (CH4) emissions to the atmosphere and could emit more CH4 with continued permafrost thaw. Aerobic methane-oxidizing bacteria may attenuate a substantial fraction of CH4 emissions in thawing permafrost peatlands; however, the impact of permafrost thaw on CH4 oxidation is uncertain. We measured potential CH4 oxidation rates (hereafter, CH4 oxidation) and their predictors using laboratory incubations and in situ porewater redox chemistry across a permafrost thaw gradient of eight thaw stages at Stordalen Mire, a permafrost peatland complex in northernmost Sweden. Methane oxidation rates increased across a gradient of permafrost thaw and differed in transitional thaw stages relative to end-member stages. Oxidation was consistently higher in submerged fens than in bogs or palsas across a range of CH4 concentrations. We also observed that CH4 oxidation increased with decreasing in situ redox potential and was highest in sites with lower redox potential (Eh \\textless 10 mV) and high water table. Our results suggest that redox potential can be used as an important predictor of CH4 oxidation, especially in thawed permafrost peatlands. Our results also highlight the importance of considering transitional thaw stages when characterizing landscape-scale CH4 dynamics, because these transitional areas have different rates and controls of CH4 oxidation relative to intact or completely thawed permafrost areas. As permafrost thaw increases the total area of semiwet and wet thaw stages in permafrost peatlands, CH4 oxidation represents an important control on CH4 emissions to the atmosphere.\n
\n\n\n\n \n\n \n \n \n \n \n \n Linking plant litter microbial diversity to microhabitat conditions, environmental gradients and litter mass loss: Insights from a European study using standard litter bags.\n \n \n \n \n\n\n \n Pioli, S.; Sarneel, J.; Thomas, H. J. D.; Domene, X.; Andrés, P.; Hefting, M.; Reitz, T.; Laudon, H.; Sandén, T.; Piscová, V.; Aurela, M.; and Brusetti, L.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 144: 107778. May 2020.\n \n\n\n\n
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\n\n\n@article{pioli_linking_2020,\n\ttitle = {Linking plant litter microbial diversity to microhabitat conditions, environmental gradients and litter mass loss: {Insights} from a {European} study using standard litter bags},\n\tvolume = {144},\n\tissn = {0038-0717},\n\tshorttitle = {Linking plant litter microbial diversity to microhabitat conditions, environmental gradients and litter mass loss},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0038071720300754},\n\tdoi = {10.1016/j.soilbio.2020.107778},\n\tabstract = {Plant litter decomposition is a key process for carbon dynamics and nutrient cycling in terrestrial ecosystems. The interaction between litter properties, climatic conditions and soil attributes, influences the activity of microorganisms responsible for litter mineralization. So far, studies using standardized litters to investigate the response of bacterial and fungal communities under different environmental conditions are scarce, especially along wide geographic ranges. We used a standardized protocol to investigate the diversity of bacteria and fungi in plant litter with the aim of: (i) comparing the microbial communities of native and exotic litters with the community of local soil along a European transect from northern Finland to southern Italy, (ii) defining whether and to what extent, litter types with different traits represent selective substrates for microbial communities, (iii) disentangling the abiotic drivers of microbial diversity, and (iv) correlating the microbial diversity and species co-occurrences patterns with litter mass loss. We buried native litter and three exotic standardized litters (Deschampsia cespitosa, rooibos tea and green tea) at 12 European study sites. We determined litter mass loss after 94 days. We used an automated molecular DNA-based fingerprinting (ARISA) to profile the bacterial and fungal communities of each litter type and soil (180 samples in total). Microbial communities in native and exotic litters differed from local soil assemblages. Green tea and D. cespitosa litter represented more selective substrates compared to native litter and rooibos. Soil moisture and soil temperature were the major drivers of microbial community structure at larger scales, though with varying patterns according to litter type. Soil attributes (i.e. moisture and C/N ratios) better explained the differences in microbial abundances than litter type. Green tea degraded faster than all other litter types and accounted for the largest number of positive co-occurrences among microbial taxa. Litter mass loss was positively correlated with fungal evenness and with the percentage of positive co-occurrences between fungi. Our findings suggest that the microbial community at larger scales reflects the complex interplay between litter type and soil attributes, with the latter exerting a major influence. Mass loss patterns are in part determined by inter- and intra-kingdom interactions and fungal diversity.},\n\tlanguage = {en},\n\turldate = {2020-03-18},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Pioli, Silvia and Sarneel, Judith and Thomas, Haydn J. D. and Domene, Xavier and Andrés, Pilar and Hefting, Mariet and Reitz, Thomas and Laudon, Hjalmar and Sandén, Taru and Piscová, Veronika and Aurela, Mika and Brusetti, Lorenzo},\n\tmonth = may,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Abiotic drivers, Litter decomposition, Microbial co-occurrences, Microbial communities' diversity, Molecular fingerprinting, Pan-European study},\n\tpages = {107778},\n}\n\n\n\n\n\n Plant litter decomposition is a key process for carbon dynamics and nutrient cycling in terrestrial ecosystems. The interaction between litter properties, climatic conditions and soil attributes, influences the activity of microorganisms responsible for litter mineralization. So far, studies using standardized litters to investigate the response of bacterial and fungal communities under different environmental conditions are scarce, especially along wide geographic ranges. We used a standardized protocol to investigate the diversity of bacteria and fungi in plant litter with the aim of: (i) comparing the microbial communities of native and exotic litters with the community of local soil along a European transect from northern Finland to southern Italy, (ii) defining whether and to what extent, litter types with different traits represent selective substrates for microbial communities, (iii) disentangling the abiotic drivers of microbial diversity, and (iv) correlating the microbial diversity and species co-occurrences patterns with litter mass loss. We buried native litter and three exotic standardized litters (Deschampsia cespitosa, rooibos tea and green tea) at 12 European study sites. We determined litter mass loss after 94 days. We used an automated molecular DNA-based fingerprinting (ARISA) to profile the bacterial and fungal communities of each litter type and soil (180 samples in total). Microbial communities in native and exotic litters differed from local soil assemblages. Green tea and D. cespitosa litter represented more selective substrates compared to native litter and rooibos. Soil moisture and soil temperature were the major drivers of microbial community structure at larger scales, though with varying patterns according to litter type. Soil attributes (i.e. moisture and C/N ratios) better explained the differences in microbial abundances than litter type. Green tea degraded faster than all other litter types and accounted for the largest number of positive co-occurrences among microbial taxa. Litter mass loss was positively correlated with fungal evenness and with the percentage of positive co-occurrences between fungi. Our findings suggest that the microbial community at larger scales reflects the complex interplay between litter type and soil attributes, with the latter exerting a major influence. Mass loss patterns are in part determined by inter- and intra-kingdom interactions and fungal diversity.\n
\n\n\n\n \n\n \n \n \n \n \n \n Changing Source-Transport Dynamics Drive Differential Browning Trends in a Boreal Stream Network.\n \n \n \n \n\n\n \n Fork, M. L.; Sponseller, R. A.; and Laudon, H.\n\n\n \n\n\n\n Water Resources Research, 56(2): e2019WR026336. 2020.\n _eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019WR026336\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{fork_changing_2020,\n\ttitle = {Changing {Source}-{Transport} {Dynamics} {Drive} {Differential} {Browning} {Trends} in a {Boreal} {Stream} {Network}},\n\tvolume = {56},\n\tcopyright = {© 2020 The Authors.},\n\tissn = {1944-7973},\n\turl = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019WR026336},\n\tdoi = {10.1029/2019WR026336},\n\tabstract = {Dissolved organic carbon (DOC) concentrations are increasing in freshwaters worldwide, with important implications for aquatic ecology, biogeochemistry, and ecosystem services. While multiple environmental changes may be responsible for these trends, predicting the occurrence and magnitude of “browning” and relating such trends to changes in DOC sources versus hydrologic transport remain key challenges. We analyzed long-term trends in DOC concentration from the two dominant landscape sources (riparian soils and mire peats) and receiving streams in a boreal catchment to evaluate how browning patterns relate to land cover and hydrology. Increases in stream DOC were widespread but not universal. Browning was most pronounced in small, forested streams, where trends corresponded to twofold to threefold increases in DOC production in riparian soils and increases in annual DOC export from a forested headwater. By contrast, DOC did not change in mire peats or streams draining catchments with high lake or mire cover, nor did we observe trends in DOC export from a mire-dominated headwater. The distinct long-term trends in DOC sources also altered concentration-discharge relationships, with a forested headwater shifting from transport-limited toward chemostasis, and a mire outlet stream shifting from chemostasis to source-limitated. Modified DOC supply to headwaters, together with altered seasonal hydrology and differences in the dominant water source along the stream network gave rise to predictable browning trends and consistent concentration-discharge relationships. Overall, our results show that the sources of DOC to boreal aquatic ecosystems are responding to environmental change in fundamentally different ways, with important consequences for browning along boreal stream networks.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-03-19},\n\tjournal = {Water Resources Research},\n\tauthor = {Fork, Megan L. and Sponseller, Ryan A. and Laudon, Hjalmar},\n\tyear = {2020},\n\tnote = {\\_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019WR026336},\n\tkeywords = {\\#nosource, DOC, brownification, concentration-discharge, flux, riparian, wetland},\n\tpages = {e2019WR026336},\n}\n\n\n\n\n\n Dissolved organic carbon (DOC) concentrations are increasing in freshwaters worldwide, with important implications for aquatic ecology, biogeochemistry, and ecosystem services. While multiple environmental changes may be responsible for these trends, predicting the occurrence and magnitude of “browning” and relating such trends to changes in DOC sources versus hydrologic transport remain key challenges. We analyzed long-term trends in DOC concentration from the two dominant landscape sources (riparian soils and mire peats) and receiving streams in a boreal catchment to evaluate how browning patterns relate to land cover and hydrology. Increases in stream DOC were widespread but not universal. Browning was most pronounced in small, forested streams, where trends corresponded to twofold to threefold increases in DOC production in riparian soils and increases in annual DOC export from a forested headwater. By contrast, DOC did not change in mire peats or streams draining catchments with high lake or mire cover, nor did we observe trends in DOC export from a mire-dominated headwater. The distinct long-term trends in DOC sources also altered concentration-discharge relationships, with a forested headwater shifting from transport-limited toward chemostasis, and a mire outlet stream shifting from chemostasis to source-limitated. Modified DOC supply to headwaters, together with altered seasonal hydrology and differences in the dominant water source along the stream network gave rise to predictable browning trends and consistent concentration-discharge relationships. Overall, our results show that the sources of DOC to boreal aquatic ecosystems are responding to environmental change in fundamentally different ways, with important consequences for browning along boreal stream networks.\n
\n\n\n\n \n\n \n \n \n \n \n \n Removal of grazers alters the response of tundra soil carbon to warming and enhanced nitrogen availability.\n \n \n \n \n\n\n \n Ylänne, H.; Kaarlejärvi, E.; Väisänen, M.; Männistö, M. K.; Ahonen, S. H. K.; Olofsson, J.; and Stark, S.\n\n\n \n\n\n\n Ecological Monographs, 90(1): e01396. 2020.\n _eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecm.1396\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{ylanne_removal_2020,\n\ttitle = {Removal of grazers alters the response of tundra soil carbon to warming and enhanced nitrogen availability},\n\tvolume = {90},\n\tcopyright = {© 2019 by the Ecological Society of America},\n\tissn = {1557-7015},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecm.1396},\n\tdoi = {10.1002/ecm.1396},\n\tabstract = {The circumpolar Arctic is currently facing multiple global changes that have the potential to alter the capacity of tundra soils to store carbon. Yet, predicting changes in soil carbon is hindered by the fact that multiple factors simultaneously control processes sustaining carbon storage and we do not understand how they act in concert. Here, we investigated the effects of warmer temperatures, enhanced soil nitrogen availability, and the combination of these on tundra carbon stocks at three different grazing regimes: on areas with over 50-yr history of either light or heavy reindeer grazing and in 5-yr-old exlosures in the heavily grazed area. In line with earlier reports, warming generally decreased soil carbon stocks. However, our results suggest that the mechanisms by which warming decreases carbon storage depend on grazing intensity: under long-term light grazing soil carbon losses were linked to higher shrub abundance and higher enzymatic activities, whereas under long-term heavy grazing, carbon losses were linked to drier soils and higher enzymatic activities. Importantly, under enhanced soil nitrogen availability, warming did not induce soil carbon losses under either of the long-term grazing regimes, whereas inside exclosures in the heavily grazed area, also the combination of warming and enhanced nutrient availability induced soil carbon loss. Grazing on its own did not influence the soil carbon stocks. These results reveal that accounting for the effect of warming or grazing alone is not sufficient to reliably predict future soil carbon storage in the tundra. Instead, the joint effects of multiple global changes need to be accounted for, with a special focus given to abrupt changes in grazing currently taking place in several parts of the Arctic.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-03-19},\n\tjournal = {Ecological Monographs},\n\tauthor = {Ylänne, Henni and Kaarlejärvi, Elina and Väisänen, Maria and Männistö, Minna K. and Ahonen, Saija H. K. and Olofsson, Johan and Stark, Sari},\n\tyear = {2020},\n\tnote = {\\_eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecm.1396},\n\tkeywords = {\\#nosource, Rangifer tarandus, SEM, fertilization, herbivory, land use, open-top chamber, reindeer, soil carbon storage},\n\tpages = {e01396},\n}\n\n\n\n\n\n The circumpolar Arctic is currently facing multiple global changes that have the potential to alter the capacity of tundra soils to store carbon. Yet, predicting changes in soil carbon is hindered by the fact that multiple factors simultaneously control processes sustaining carbon storage and we do not understand how they act in concert. Here, we investigated the effects of warmer temperatures, enhanced soil nitrogen availability, and the combination of these on tundra carbon stocks at three different grazing regimes: on areas with over 50-yr history of either light or heavy reindeer grazing and in 5-yr-old exlosures in the heavily grazed area. In line with earlier reports, warming generally decreased soil carbon stocks. However, our results suggest that the mechanisms by which warming decreases carbon storage depend on grazing intensity: under long-term light grazing soil carbon losses were linked to higher shrub abundance and higher enzymatic activities, whereas under long-term heavy grazing, carbon losses were linked to drier soils and higher enzymatic activities. Importantly, under enhanced soil nitrogen availability, warming did not induce soil carbon losses under either of the long-term grazing regimes, whereas inside exclosures in the heavily grazed area, also the combination of warming and enhanced nutrient availability induced soil carbon loss. Grazing on its own did not influence the soil carbon stocks. These results reveal that accounting for the effect of warming or grazing alone is not sufficient to reliably predict future soil carbon storage in the tundra. Instead, the joint effects of multiple global changes need to be accounted for, with a special focus given to abrupt changes in grazing currently taking place in several parts of the Arctic.\n
\n\n\n\n \n\n \n \n \n \n \n \n Changes in nutritional quality and nutrient limitation regimes of phytoplankton in response to declining N deposition in mountain lakes.\n \n \n \n \n\n\n \n Bergström, A.; Jonsson, A.; Isles, P. D. F.; Creed, I. F.; and Lau, D. C. P.\n\n\n \n\n\n\n Aquatic Sciences, 82(2): 31. February 2020.\n \n\n\n\n
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\n\n\n@article{bergstrom_changes_2020,\n\ttitle = {Changes in nutritional quality and nutrient limitation regimes of phytoplankton in response to declining {N} deposition in mountain lakes},\n\tvolume = {82},\n\tissn = {1420-9055},\n\turl = {https://doi.org/10.1007/s00027-020-0697-1},\n\tdoi = {10.1007/s00027-020-0697-1},\n\tabstract = {Phytoplankton play a key role in supporting aquatic food webs. However, the effects of ongoing large-scale changes in the concentrations and stoichiometry of important biological compounds [dissolved inorganic N (DIN), total phosphorus (TP), dissolved organic carbon (DOC) and DIN:TP] on the development and nutritional quality of phytoplankton for higher trophic levels are unclear. We conducted lake studies and in situ bioassay experiments in two Swedish mountain regions [Abisko (north) and Jämtland (south)] with different N deposition and where lakes in each region were distributed along a similar gradient in lake DOC (2–7 mg L−1) to assess whether differences in nutrients, DOC and DIN:TP induced differences in phytoplankton quantity [chlorophyll a (Chl-a) and seston carbon (C)] and quality [seston C:N:P stoichiometry and fatty acid (FA) composition]. Using long-term monitoring data from lakes in these two mountain regions, we found declining long-term trends in N deposition and lake DIN and total TP concentrations, but not in lake DIN:TP. Lakes in Abisko received lower N deposition and had lower DIN:TP than those in Jämtland. Phytoplankton was N- to NP-limited in Abisko lakes but NP dual-limited in Jämtland lakes. The N fertilization effects induced by higher DIN:TP were weak on phytoplankton quantity but strong on phytoplankton quality. The phytoplankton had lower eicosapentaenoic acid (EPA) content and higher P content (lower seston C:P) in Abisko compared to in Jämtland. In addition, the quality of the DOC (as indicated by its aromaticity and SUVA) influenced not only the light conditions and the seston C:P ratios, but also the FA composition. We found higher bacteria FA concentrations in seston in Abisko than in Jämtland, despite lower amounts of FA of terrestrial origin in Abisko. Our findings suggest that declining N deposition and enhanced colored terrestrial C loadings leads to lower nutritional quality of basal resources for higher consumers in mountain lakes.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-03-19},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Bergström, Ann-Kristin and Jonsson, Anders and Isles, Peter D. F. and Creed, Irena F. and Lau, Danny C. P.},\n\tmonth = feb,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {31},\n}\n\n\n\n\n\n Phytoplankton play a key role in supporting aquatic food webs. However, the effects of ongoing large-scale changes in the concentrations and stoichiometry of important biological compounds [dissolved inorganic N (DIN), total phosphorus (TP), dissolved organic carbon (DOC) and DIN:TP] on the development and nutritional quality of phytoplankton for higher trophic levels are unclear. We conducted lake studies and in situ bioassay experiments in two Swedish mountain regions [Abisko (north) and Jämtland (south)] with different N deposition and where lakes in each region were distributed along a similar gradient in lake DOC (2–7 mg L−1) to assess whether differences in nutrients, DOC and DIN:TP induced differences in phytoplankton quantity [chlorophyll a (Chl-a) and seston carbon (C)] and quality [seston C:N:P stoichiometry and fatty acid (FA) composition]. Using long-term monitoring data from lakes in these two mountain regions, we found declining long-term trends in N deposition and lake DIN and total TP concentrations, but not in lake DIN:TP. Lakes in Abisko received lower N deposition and had lower DIN:TP than those in Jämtland. Phytoplankton was N- to NP-limited in Abisko lakes but NP dual-limited in Jämtland lakes. The N fertilization effects induced by higher DIN:TP were weak on phytoplankton quantity but strong on phytoplankton quality. The phytoplankton had lower eicosapentaenoic acid (EPA) content and higher P content (lower seston C:P) in Abisko compared to in Jämtland. In addition, the quality of the DOC (as indicated by its aromaticity and SUVA) influenced not only the light conditions and the seston C:P ratios, but also the FA composition. We found higher bacteria FA concentrations in seston in Abisko than in Jämtland, despite lower amounts of FA of terrestrial origin in Abisko. Our findings suggest that declining N deposition and enhanced colored terrestrial C loadings leads to lower nutritional quality of basal resources for higher consumers in mountain lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stream metabolism controls diel patterns and evasion of CO $_{\\textrm{2}}$ in Arctic streams.\n \n \n \n \n\n\n \n Rocher‐Ros, G.; Sponseller, R. A.; Bergström, A.; Myrstener, M.; and Giesler, R.\n\n\n \n\n\n\n Global Change Biology, 26(3): 1400–1413. March 2020.\n \n\n\n\n
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\n\n\n@article{rocherros_stream_2020,\n\ttitle = {Stream metabolism controls diel patterns and evasion of {CO} $_{\\textrm{2}}$ in {Arctic} streams},\n\tvolume = {26},\n\tissn = {1354-1013, 1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14895},\n\tdoi = {10.1111/gcb.14895},\n\tabstract = {Streams play an important role in the global carbon (C) cycle, accounting for a large portion of CO2 evaded from inland waters despite their small areal coverage. However, the relative importance of different terrestrial and aquatic processes driving CO2 production and evasion from streams remains poorly understood. In this study, we measured O2 and CO2 continuously in streams draining tundra-dominated catchments in northern Sweden, during the summers of 2015 and 2016. From this, we estimated daily metabolic rates and CO2 evasion simultaneously and thus provide insight into the role of stream metabolism as a driver of C dynamics in Arctic streams. Our results show that aquatic biological processes regulate CO2 concentrations and evasion at multiple timescales. Photosynthesis caused CO2 concentrations to decrease by as much as 900 ppm during the day, with the magnitude of this diel variation being strongest at the low-turbulence streams. Diel patterns in CO2 concentrations in turn influenced evasion, with up to 45\\% higher rates at night. Throughout the summer, CO2 evasion was sustained by aquatic ecosystem respiration, which was one order of magnitude higher than gross primary production. Furthermore, in most cases, the contribution of stream respiration exceeded CO2 evasion, suggesting that some stream reaches serve as net sources of CO2, thus creating longitudinal heterogeneity in C production and loss within this stream network. Overall, our results provide the first link between stream metabolism and CO2 evasion in the Arctic and demonstrate that stream metabolic processes are key drivers of the transformation and fate of terrestrial organic matter exported from these landscapes.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-03-19},\n\tjournal = {Global Change Biology},\n\tauthor = {Rocher‐Ros, Gerard and Sponseller, Ryan A. and Bergström, Ann‐Kristin and Myrstener, Maria and Giesler, Reiner},\n\tmonth = mar,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {1400--1413},\n}\n\n\n\n\n\n Streams play an important role in the global carbon (C) cycle, accounting for a large portion of CO2 evaded from inland waters despite their small areal coverage. However, the relative importance of different terrestrial and aquatic processes driving CO2 production and evasion from streams remains poorly understood. In this study, we measured O2 and CO2 continuously in streams draining tundra-dominated catchments in northern Sweden, during the summers of 2015 and 2016. From this, we estimated daily metabolic rates and CO2 evasion simultaneously and thus provide insight into the role of stream metabolism as a driver of C dynamics in Arctic streams. Our results show that aquatic biological processes regulate CO2 concentrations and evasion at multiple timescales. Photosynthesis caused CO2 concentrations to decrease by as much as 900 ppm during the day, with the magnitude of this diel variation being strongest at the low-turbulence streams. Diel patterns in CO2 concentrations in turn influenced evasion, with up to 45% higher rates at night. Throughout the summer, CO2 evasion was sustained by aquatic ecosystem respiration, which was one order of magnitude higher than gross primary production. Furthermore, in most cases, the contribution of stream respiration exceeded CO2 evasion, suggesting that some stream reaches serve as net sources of CO2, thus creating longitudinal heterogeneity in C production and loss within this stream network. Overall, our results provide the first link between stream metabolism and CO2 evasion in the Arctic and demonstrate that stream metabolic processes are key drivers of the transformation and fate of terrestrial organic matter exported from these landscapes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Vegetation and soil responses to added carbon and nutrients remain six years after discontinuation of long-term treatments.\n \n \n \n \n\n\n \n Liu, N.; Michelsen, A.; and Rinnan, R.\n\n\n \n\n\n\n Science of The Total Environment, 722: 137885. June 2020.\n \n\n\n\n
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\n\n\n@article{liu_vegetation_2020,\n\ttitle = {Vegetation and soil responses to added carbon and nutrients remain six years after discontinuation of long-term treatments},\n\tvolume = {722},\n\tissn = {0048-9697},\n\turl = {http://www.sciencedirect.com/science/article/pii/S004896972031398X},\n\tdoi = {10.1016/j.scitotenv.2020.137885},\n\tabstract = {Global warming and increased nutrient availability in the Arctic have attracted wide attention. However, it is unknown how an increased supply of nitrogen (N), phosphorus (P) and/or labile carbon (C) – alone and in combinations – affects the concentrations and pools of C and nutrients in plants, soil and soil microorganisms, and whether the cessation of these additions allows the ecosystem to recover from amendments. Six treatments (control, C, N, P, NP and C + NP) were applied at a subarctic heath for 8–10 years. After being untreated for two years, amendments were re-applied to one half of the plots for four years while the other plot half received no amendments. When the plots were harvested, we could therefore compare responses in plots with nearly continuous 14–16-year amendments to those with six years with discontinued treatments. The responses to individual and combined nutrient additions were mostly similar in re-initiated and discontinued plots. Individual N addition strongly increased the C and N pools in the graminoids, thereby also increasing the C and N pools in litter and fine roots compared to the plots without added N. This contributed to the increased microbial biomass C and total C in soil. P addition alone increased C and N pools in vascular cryptogams, as well as PO43−, NH4+, dissolved organic carbon and dissolved organic nitrogen concentrations in soil compared to the plots without added P. Hence, plant functional groups showed differential responses to long-term N and P amendment, and after the initial nutrient additions for 8–10 years, the investigated subarctic tundra ecosystem had reached a new steady state that was resilient to further changes still six years after cessation of additions.},\n\tlanguage = {en},\n\turldate = {2020-04-23},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Liu, Na and Michelsen, Anders and Rinnan, Riikka},\n\tmonth = jun,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Arctic vegetation, Fertilization, Nitrogen, Nutrient limitation, Phosphorus, Tundra ecosystem},\n\tpages = {137885},\n}\n\n\n\n\n\n Global warming and increased nutrient availability in the Arctic have attracted wide attention. However, it is unknown how an increased supply of nitrogen (N), phosphorus (P) and/or labile carbon (C) – alone and in combinations – affects the concentrations and pools of C and nutrients in plants, soil and soil microorganisms, and whether the cessation of these additions allows the ecosystem to recover from amendments. Six treatments (control, C, N, P, NP and C + NP) were applied at a subarctic heath for 8–10 years. After being untreated for two years, amendments were re-applied to one half of the plots for four years while the other plot half received no amendments. When the plots were harvested, we could therefore compare responses in plots with nearly continuous 14–16-year amendments to those with six years with discontinued treatments. The responses to individual and combined nutrient additions were mostly similar in re-initiated and discontinued plots. Individual N addition strongly increased the C and N pools in the graminoids, thereby also increasing the C and N pools in litter and fine roots compared to the plots without added N. This contributed to the increased microbial biomass C and total C in soil. P addition alone increased C and N pools in vascular cryptogams, as well as PO43−, NH4+, dissolved organic carbon and dissolved organic nitrogen concentrations in soil compared to the plots without added P. Hence, plant functional groups showed differential responses to long-term N and P amendment, and after the initial nutrient additions for 8–10 years, the investigated subarctic tundra ecosystem had reached a new steady state that was resilient to further changes still six years after cessation of additions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Does browning affect the identity of limiting nutrients in lakes?.\n \n \n \n \n\n\n \n Isles, P. D. F.; Jonsson, A.; Creed, I. F.; and Bergström, A.\n\n\n \n\n\n\n Aquatic Sciences, 82(2): 45. March 2020.\n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{isles_does_2020,\n\ttitle = {Does browning affect the identity of limiting nutrients in lakes?},\n\tvolume = {82},\n\tissn = {1420-9055},\n\turl = {https://doi.org/10.1007/s00027-020-00718-y},\n\tdoi = {10.1007/s00027-020-00718-y},\n\tabstract = {Concentrations of dissolved organic carbon (DOC) have increased recently in many lakes at high latitudes in North America and Europe, but it is unclear what effect this will have on the identity of the limiting nutrient for phytoplankton [nitrogen (N) vs. phosphorus (P)]. Identifying the effect of changing DOC on phytoplankton nutrient limitation is complicated by spatial covariation between atmospheric N deposition and increasing DOC in areas where lake browning occurs. We conducted nutrient-limitation assays in 27 lakes from three sites along gradients of climate and atmospheric N deposition in Sweden. Within each site, lakes were selected to represent the range of DOC concentrations. We also conducted statistical analyses of large-scale lake survey data (n = 4768 lakes divided into 47 regions) to investigate relationships between DOC and nutrient stoichiometry while controlling for differences in N deposition. Our findings confirmed that most lakes were dual-limited by both N and P in the south, whereas northern lakes were primarily N-limited. Throughout Sweden the ratio of dissolved inorganic nitrogen (DIN) to total phosphorus (TP) declined with increasing DOC in most regions, suggesting that browner lakes are more likely to be N limited. These results were not supported by our nutrient limitation assays, which identified no relationship between DOC and relative strength of limitation by N or P. Increased DOC also resulted in significant increases in both total and inorganic N and P fractions, suggesting that other factors such as light limitation or increased top-down control become more important as DOC increases.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-04-23},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Isles, Peter D. F. and Jonsson, Anders and Creed, Irena F. and Bergström, Ann-Kristin},\n\tmonth = mar,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {45},\n}\n\n\n\n\n\n Concentrations of dissolved organic carbon (DOC) have increased recently in many lakes at high latitudes in North America and Europe, but it is unclear what effect this will have on the identity of the limiting nutrient for phytoplankton [nitrogen (N) vs. phosphorus (P)]. Identifying the effect of changing DOC on phytoplankton nutrient limitation is complicated by spatial covariation between atmospheric N deposition and increasing DOC in areas where lake browning occurs. We conducted nutrient-limitation assays in 27 lakes from three sites along gradients of climate and atmospheric N deposition in Sweden. Within each site, lakes were selected to represent the range of DOC concentrations. We also conducted statistical analyses of large-scale lake survey data (n = 4768 lakes divided into 47 regions) to investigate relationships between DOC and nutrient stoichiometry while controlling for differences in N deposition. Our findings confirmed that most lakes were dual-limited by both N and P in the south, whereas northern lakes were primarily N-limited. Throughout Sweden the ratio of dissolved inorganic nitrogen (DIN) to total phosphorus (TP) declined with increasing DOC in most regions, suggesting that browner lakes are more likely to be N limited. These results were not supported by our nutrient limitation assays, which identified no relationship between DOC and relative strength of limitation by N or P. Increased DOC also resulted in significant increases in both total and inorganic N and P fractions, suggesting that other factors such as light limitation or increased top-down control become more important as DOC increases.\n
\n\n\n\n \n\n \n \n \n \n \n \n Drought alters the biogeochemistry of boreal stream networks.\n \n \n \n \n\n\n \n Gómez-Gener, L.; Lupon, A.; Laudon, H.; and Sponseller, R. A.\n\n\n \n\n\n\n Nature Communications, 11(1): 1–11. April 2020.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{gomez-gener_drought_2020,\n\ttitle = {Drought alters the biogeochemistry of boreal stream networks},\n\tvolume = {11},\n\tcopyright = {2020 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-020-15496-2},\n\tdoi = {10.1038/s41467-020-15496-2},\n\tabstract = {High latitude droughts are increasing, but their effects on freshwater systems are poorly understood. Here the authors investigate Sweden’s most severe drought in the last century and show that these dry conditions induce hypoxia and elevated methane production from streams.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-04-23},\n\tjournal = {Nature Communications},\n\tauthor = {Gómez-Gener, Lluís and Lupon, Anna and Laudon, Hjalmar and Sponseller, Ryan A.},\n\tmonth = apr,\n\tyear = {2020},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {1--11},\n}\n\n\n\n\n\n High latitude droughts are increasing, but their effects on freshwater systems are poorly understood. Here the authors investigate Sweden’s most severe drought in the last century and show that these dry conditions induce hypoxia and elevated methane production from streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Availability of specific prey types impact pied flycatcher (Ficedula hypoleuca) nestling health in a moderately lead contaminated environment in northern Sweden.\n \n \n \n \n\n\n \n Lidman, J.; Jonsson, M.; and Berglund, Å. M. M.\n\n\n \n\n\n\n Environmental Pollution, 257: 113478. February 2020.\n \n\n\n\n
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\n\n\n@article{lidman_availability_2020,\n\ttitle = {Availability of specific prey types impact pied flycatcher ({Ficedula} hypoleuca) nestling health in a moderately lead contaminated environment in northern {Sweden}},\n\tvolume = {257},\n\tissn = {0269-7491},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0269749119324418},\n\tdoi = {10.1016/j.envpol.2019.113478},\n\tabstract = {Anthropogenic metal contamination can cause increased stress in exposed organisms, but it can be difficult to disentangle the anthropogenic influence from natural variation in environmental conditions. In the proximity of a closed lead (Pb)/zinc (Zn) mine in northern Sweden, the health effects of Pb exposure, essential element (calcium [Ca] and Zn) uptake, and prey availability and composition were estimated on pied flycatcher (Ficedula hypoleuca) nestlings, using hemoglobin (Hb) level as a proxy for health. Pb concentration in nestling blood range between 0.00034 and 2.21 μg/g (ww) and nestlings close to the mine had higher Pb concentrations and lower Hb, but contrary to our hypothesis, Hb was not directly related to Pb accumulation. Proportions of flying terrestrial and aquatic insects in available prey and availability of flying terrestrial insects were positively associated with nestling Hb, whereas the proportion of terrestrial ground living prey, the most common prey type, showed a negative association. This suggests that positive influence of certain prey, which does not have to be the most common in the surroundings, can counteract the negative effects from Pb contamination on bird health. Nestlings inhabiting sites adjacent to lakes had an advantage in terms of prey composition and availability of preferred prey, which resulted in higher Hb. As such, our results show that during moderate exposure to metals, variation in natural conditions, such as prey availability, can have great impact on organism health compared to Pb exposure.},\n\tlanguage = {en},\n\turldate = {2020-04-23},\n\tjournal = {Environmental Pollution},\n\tauthor = {Lidman, Johan and Jonsson, Micael and Berglund, Åsa M. M.},\n\tmonth = feb,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Anthropogenic stressor, Hemoglobin, Metal exposure, Passerine, Prey availability},\n\tpages = {113478},\n}\n\n\n\n\n\n Anthropogenic metal contamination can cause increased stress in exposed organisms, but it can be difficult to disentangle the anthropogenic influence from natural variation in environmental conditions. In the proximity of a closed lead (Pb)/zinc (Zn) mine in northern Sweden, the health effects of Pb exposure, essential element (calcium [Ca] and Zn) uptake, and prey availability and composition were estimated on pied flycatcher (Ficedula hypoleuca) nestlings, using hemoglobin (Hb) level as a proxy for health. Pb concentration in nestling blood range between 0.00034 and 2.21 μg/g (ww) and nestlings close to the mine had higher Pb concentrations and lower Hb, but contrary to our hypothesis, Hb was not directly related to Pb accumulation. Proportions of flying terrestrial and aquatic insects in available prey and availability of flying terrestrial insects were positively associated with nestling Hb, whereas the proportion of terrestrial ground living prey, the most common prey type, showed a negative association. This suggests that positive influence of certain prey, which does not have to be the most common in the surroundings, can counteract the negative effects from Pb contamination on bird health. Nestlings inhabiting sites adjacent to lakes had an advantage in terms of prey composition and availability of preferred prey, which resulted in higher Hb. As such, our results show that during moderate exposure to metals, variation in natural conditions, such as prey availability, can have great impact on organism health compared to Pb exposure.\n
\n\n\n\n \n\n \n \n \n \n \n \n The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies (ClimEx).\n \n \n \n \n\n\n \n Halbritter, A. H.; Boeck, H. J. D.; Eycott, A. E.; Reinsch, S.; Robinson, D. A.; Vicca, S.; Berauer, B.; Christiansen, C. T.; Estiarte, M.; Grünzweig, J. M.; Gya, R.; Hansen, K.; Jentsch, A.; Lee, H.; Linder, S.; Marshall, J.; Peñuelas, J.; Schmidt, I. K.; Stuart‐Haëntjens, E.; Wilfahrt, P.; and Vandvik, V.\n\n\n \n\n\n\n Methods in Ecology and Evolution, 11(1): 22–37. 2020.\n _eprint: https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.13331\n\n\n\n
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\n\n\n@article{halbritter_handbook_2020,\n\ttitle = {The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies ({ClimEx})},\n\tvolume = {11},\n\tcopyright = {© 2019 The Authors. Methods in Ecology and Evolution published by John Wiley \\& Sons Ltd on behalf of British Ecological Society.},\n\tissn = {2041-210X},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/2041-210X.13331},\n\tdoi = {10.1111/2041-210X.13331},\n\tabstract = {Climate change is a world-wide threat to biodiversity and ecosystem structure, functioning and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate change impacts across the soil–plant–atmosphere continuum. An increasing number of climate change studies are creating new opportunities for meaningful and high-quality generalizations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re-use, synthesis and upscaling. Many of these challenges relate to a lack of an established ‘best practice’ for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change. To overcome these challenges, we collected best-practice methods emerging from major ecological research networks and experiments, as synthesized by 115 experts from across a wide range of scientific disciplines. Our handbook contains guidance on the selection of response variables for different purposes, protocols for standardized measurements of 66 such response variables and advice on data management. Specifically, we recommend a minimum subset of variables that should be collected in all climate change studies to allow data re-use and synthesis, and give guidance on additional variables critical for different types of synthesis and upscaling. The goal of this community effort is to facilitate awareness of the importance and broader application of standardized methods to promote data re-use, availability, compatibility and transparency. We envision improved research practices that will increase returns on investments in individual research projects, facilitate second-order research outputs and create opportunities for collaboration across scientific communities. Ultimately, this should significantly improve the quality and impact of the science, which is required to fulfil society's needs in a changing world.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-04-23},\n\tjournal = {Methods in Ecology and Evolution},\n\tauthor = {Halbritter, Aud H. and Boeck, Hans J. De and Eycott, Amy E. and Reinsch, Sabine and Robinson, David A. and Vicca, Sara and Berauer, Bernd and Christiansen, Casper T. and Estiarte, Marc and Grünzweig, José M. and Gya, Ragnhild and Hansen, Karin and Jentsch, Anke and Lee, Hanna and Linder, Sune and Marshall, John and Peñuelas, Josep and Schmidt, Inger Kappel and Stuart‐Haëntjens, Ellen and Wilfahrt, Peter and Vandvik, Vigdis},\n\tyear = {2020},\n\tnote = {\\_eprint: https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.13331},\n\tkeywords = {\\#nosource, best practice, coordinated experiments, data management and documentation, ecosystem, experimental macroecology, methodology, open science, vegetation},\n\tpages = {22--37},\n}\n\n\n\n\n\n Climate change is a world-wide threat to biodiversity and ecosystem structure, functioning and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate change impacts across the soil–plant–atmosphere continuum. An increasing number of climate change studies are creating new opportunities for meaningful and high-quality generalizations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re-use, synthesis and upscaling. Many of these challenges relate to a lack of an established ‘best practice’ for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change. To overcome these challenges, we collected best-practice methods emerging from major ecological research networks and experiments, as synthesized by 115 experts from across a wide range of scientific disciplines. Our handbook contains guidance on the selection of response variables for different purposes, protocols for standardized measurements of 66 such response variables and advice on data management. Specifically, we recommend a minimum subset of variables that should be collected in all climate change studies to allow data re-use and synthesis, and give guidance on additional variables critical for different types of synthesis and upscaling. The goal of this community effort is to facilitate awareness of the importance and broader application of standardized methods to promote data re-use, availability, compatibility and transparency. We envision improved research practices that will increase returns on investments in individual research projects, facilitate second-order research outputs and create opportunities for collaboration across scientific communities. Ultimately, this should significantly improve the quality and impact of the science, which is required to fulfil society's needs in a changing world.\n
\n\n\n\n \n\n \n \n \n \n \n \n Simulated rhizosphere deposits induce microbial N-mining that may accelerate shrubification in the subarctic.\n \n \n \n \n\n\n \n Hicks, L. C.; Leizeaga, A.; Rousk, K.; Michelsen, A.; and Rousk, J.\n\n\n \n\n\n\n Ecology, n/a(n/a): e03094. May 2020.\n _eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.3094\n\n\n\n
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\n\n\n@article{hicks_simulated_2020,\n\ttitle = {Simulated rhizosphere deposits induce microbial {N}-mining that may accelerate shrubification in the subarctic},\n\tvolume = {n/a},\n\tcopyright = {This article is protected by copyright. All rights reserved.},\n\tissn = {1939-9170},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.3094},\n\tdoi = {10.1002/ecy.3094},\n\tabstract = {Climate change is exposing high-latitude systems to warming and a shift towards more shrub-dominated plant communities, resulting in increased leaf-litter inputs at the soil surface, and more labile root-derived organic matter (OM) input in the soil profile. Labile OM can stimulate the mineralization of soil organic matter (SOM); a phenomenon termed “priming”. In N-poor subarctic soils, it is hypothesized that microorganisms may “prime” SOM in order to acquire N (“microbial N-mining”). Increased leaf-litter inputs with a high C/N ratio might further exacerbate microbial N demand, and increase the susceptibility of N-poor soils to N-mining. We investigated the N-control of SOM mineralization by amending soils from climate change simulation treatments in the subarctic (+1.1°C warming, birch litter addition, willow litter addition, and fungal sporocarp addition) with labile OM either in the form of glucose (labile C; equivalent to 400 µg C g-1 fwt soil) or alanine (labile C + N; equivalent to 400 µg C and 157 µg N g-1 fwt soil), to simulate rhizosphere inputs. Surprisingly, we found that despite five-years of simulated climate change treatments, there were no significant effects of the field-treatments on microbial process rates, community structure or responses to labile OM. Glucose primed the mineralization of both C and N from SOM, but gross mineralization of N was stimulated more than that of C, suggesting that microbial SOM-use increased in magnitude and shifted to components richer in N (i.e. selective microbial N-mining). The addition of alanine also resulted in priming of both C and N mineralization, but the N mineralization stimulated by alanine was greater than that stimulated by glucose, indicating strong N-mining even when a source of labile OM including N was supplied. Microbial carbon use efficiency was reduced in response to both labile OM inputs. Overall, these findings suggest that shrub-expansion could fundamentally alter biogeochemical cycling in the subarctic, yielding more N available for plant uptake in these N-limited soils, thus driving positive plant-soil feedbacks.},\n\tlanguage = {en},\n\tnumber = {n/a},\n\turldate = {2020-05-29},\n\tjournal = {Ecology},\n\tauthor = {Hicks, Lettice C. and Leizeaga, Ainara and Rousk, Kathrin and Michelsen, Anders and Rousk, Johannes},\n\tmonth = may,\n\tyear = {2020},\n\tnote = {\\_eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.3094},\n\tkeywords = {\\#nosource, carbon and nitrogen mineralization, climate change, microbial carbon use efficiency, nitrogen limitation, nitrogen-mining, rhizosphere biogeochemistry, soil priming effect, subarctic tundra},\n\tpages = {e03094},\n}\n\n\n\n\n\n Climate change is exposing high-latitude systems to warming and a shift towards more shrub-dominated plant communities, resulting in increased leaf-litter inputs at the soil surface, and more labile root-derived organic matter (OM) input in the soil profile. Labile OM can stimulate the mineralization of soil organic matter (SOM); a phenomenon termed “priming”. In N-poor subarctic soils, it is hypothesized that microorganisms may “prime” SOM in order to acquire N (“microbial N-mining”). Increased leaf-litter inputs with a high C/N ratio might further exacerbate microbial N demand, and increase the susceptibility of N-poor soils to N-mining. We investigated the N-control of SOM mineralization by amending soils from climate change simulation treatments in the subarctic (+1.1°C warming, birch litter addition, willow litter addition, and fungal sporocarp addition) with labile OM either in the form of glucose (labile C; equivalent to 400 µg C g-1 fwt soil) or alanine (labile C + N; equivalent to 400 µg C and 157 µg N g-1 fwt soil), to simulate rhizosphere inputs. Surprisingly, we found that despite five-years of simulated climate change treatments, there were no significant effects of the field-treatments on microbial process rates, community structure or responses to labile OM. Glucose primed the mineralization of both C and N from SOM, but gross mineralization of N was stimulated more than that of C, suggesting that microbial SOM-use increased in magnitude and shifted to components richer in N (i.e. selective microbial N-mining). The addition of alanine also resulted in priming of both C and N mineralization, but the N mineralization stimulated by alanine was greater than that stimulated by glucose, indicating strong N-mining even when a source of labile OM including N was supplied. Microbial carbon use efficiency was reduced in response to both labile OM inputs. Overall, these findings suggest that shrub-expansion could fundamentally alter biogeochemical cycling in the subarctic, yielding more N available for plant uptake in these N-limited soils, thus driving positive plant-soil feedbacks.\n
\n\n\n\n \n\n \n \n \n \n \n \n Comparing the effects of soil fauna on litter decomposition and organic matter turnover in sustainably and conventionally managed olive orchards.\n \n \n \n \n\n\n \n Sofo, A.; Nicoletta Mininni, A.; and Ricciuti, P.\n\n\n \n\n\n\n Geoderma, 372: 114393. August 2020.\n \n\n\n\n
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\n\n\n@article{sofo_comparing_2020,\n\ttitle = {Comparing the effects of soil fauna on litter decomposition and organic matter turnover in sustainably and conventionally managed olive orchards},\n\tvolume = {372},\n\tissn = {0016-7061},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0016706119325935},\n\tdoi = {10.1016/j.geoderma.2020.114393},\n\tabstract = {Soils and crops in Mediterranean agrosystems are vulnerable to climate change and environmental stresses, and they will be more and more in the next future. In this scenario, soil organic matter (SOM) plays a crucial role and its level is principally determined by the continuous physical and chemical action of soil fauna. While the importance of microorganisms in fruit agrosystems has been extensively and recently highlighted, the role of soil fauna - and particularly of macrofauna - to ecosystem services has been often overlooked. On this basis, the aim of this study was to characterize and compare C/N dynamics and other soil physicochemical parameters, soil macrofauna abundance, bioturbation and litter/SOM decomposition indices in a Mediterranean olive (Olea europaea L.) orchard subjected to two different soil management systems (namely sustainable, Smng, and conventional, Cmng) for 18 years. The adoption of the Smng system significantly increased almost three times the abundance of earthworms and two times that of other soil macrofauna. Bioturbation due to soil fauna and roots was significantly higher in the Smng system, and this caused a significantly faster SOM decomposition measured both in 90-day incubated local litter bags (decomposition constant = 0.092 and 0.072 in the Smng and Cmng system, respectively) and in tea bags (decomposition rate constant = 0.018 and 0.010 in the Smng and Cmng system, respectively). Soil C and N dynamics were also affected by different soil management. The results highlighted that the soil chemical quality of the Smng system is the result of the higher abundance and activity of soil fauna, in terms of enhanced litter decomposition and bioturbation. From the general analysis of the data obtained, it emerged that the role of soil fauna should be seriously taken into account in land management strategies not exclusively oriented to fruit yield and quality, but also to soil fertility restoration.},\n\tlanguage = {en},\n\turldate = {2020-05-29},\n\tjournal = {Geoderma},\n\tauthor = {Sofo, Adriano and Nicoletta Mininni, Alba and Ricciuti, Patrizia},\n\tmonth = aug,\n\tyear = {2020},\n\tkeywords = {\\#nosource, Bioturbation, Litter decomposition, Olive orchards, Soil fauna, Sustainable land use, Tea bags},\n\tpages = {114393},\n}\n\n\n\n\n\n Soils and crops in Mediterranean agrosystems are vulnerable to climate change and environmental stresses, and they will be more and more in the next future. In this scenario, soil organic matter (SOM) plays a crucial role and its level is principally determined by the continuous physical and chemical action of soil fauna. While the importance of microorganisms in fruit agrosystems has been extensively and recently highlighted, the role of soil fauna - and particularly of macrofauna - to ecosystem services has been often overlooked. On this basis, the aim of this study was to characterize and compare C/N dynamics and other soil physicochemical parameters, soil macrofauna abundance, bioturbation and litter/SOM decomposition indices in a Mediterranean olive (Olea europaea L.) orchard subjected to two different soil management systems (namely sustainable, Smng, and conventional, Cmng) for 18 years. The adoption of the Smng system significantly increased almost three times the abundance of earthworms and two times that of other soil macrofauna. Bioturbation due to soil fauna and roots was significantly higher in the Smng system, and this caused a significantly faster SOM decomposition measured both in 90-day incubated local litter bags (decomposition constant = 0.092 and 0.072 in the Smng and Cmng system, respectively) and in tea bags (decomposition rate constant = 0.018 and 0.010 in the Smng and Cmng system, respectively). Soil C and N dynamics were also affected by different soil management. The results highlighted that the soil chemical quality of the Smng system is the result of the higher abundance and activity of soil fauna, in terms of enhanced litter decomposition and bioturbation. From the general analysis of the data obtained, it emerged that the role of soil fauna should be seriously taken into account in land management strategies not exclusively oriented to fruit yield and quality, but also to soil fertility restoration.\n
\n\n\n\n \n\n \n \n \n \n \n \n Recent Trends in Freshwater Influx to the Arctic Ocean from Four Major Arctic-Draining Rivers.\n \n \n \n \n\n\n \n Ahmed, R.; Prowse, T.; Dibike, Y.; Bonsal, B.; and O’Neil, H.\n\n\n \n\n\n\n Water, 12(4): 1189. April 2020.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{ahmed_recent_2020,\n\ttitle = {Recent {Trends} in {Freshwater} {Influx} to the {Arctic} {Ocean} from {Four} {Major} {Arctic}-{Draining} {Rivers}},\n\tvolume = {12},\n\tissn = {2073-4441},\n\turl = {https://www.mdpi.com/2073-4441/12/4/1189},\n\tdoi = {10.3390/w12041189},\n\tabstract = {Runoff from Arctic rivers constitutes a major freshwater influx to the Arctic Ocean. In these nival-dominated river systems, the majority of annual discharge is released during the spring snowmelt period. The circulation regime of the salinity-stratified Arctic Ocean is connected to global earth–ocean dynamics through thermohaline circulation; hence, variability in freshwater input from the Arctic flowing rivers has important implications for the global climate system. Daily discharge data from each of the four largest Arctic-draining river watersheds (Mackenzie, Ob, Lena and Yenisei; herein referred to as MOLY) are analyzed to identify historic changes in the magnitude and timing of freshwater input to the Arctic Ocean with emphasis on the spring freshet. Results show that the total freshwater influx to the Arctic Ocean increased by 89 km3/decade, amounting to a 14\\% increase during the 30-year period from 1980 to 2009. A distinct shift towards earlier melt timing is also indicated by proportional increases in fall, winter and spring discharges (by 2.5\\%, 1.3\\% and 2.5\\% respectively) followed by a decrease (by 5.8\\%) in summer discharge as a percentage of the mean annual flow. This seasonal increase in discharge and earlier pulse onset dates indicates a general shift towards a flatter, broad-based hydrograph with earlier peak discharges. The study also reveals that the increasing trend in freshwater discharge to the Arctic Ocean is not solely due to increased spring freshet discharge, but is a combination of increases in all seasons except that of the summer.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-29},\n\tjournal = {Water},\n\tauthor = {Ahmed, Roxanne and Prowse, Terry and Dibike, Yonas and Bonsal, Barrie and O’Neil, Hayley},\n\tmonth = apr,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {1189},\n}\n\n\n\n\n\n Runoff from Arctic rivers constitutes a major freshwater influx to the Arctic Ocean. In these nival-dominated river systems, the majority of annual discharge is released during the spring snowmelt period. The circulation regime of the salinity-stratified Arctic Ocean is connected to global earth–ocean dynamics through thermohaline circulation; hence, variability in freshwater input from the Arctic flowing rivers has important implications for the global climate system. Daily discharge data from each of the four largest Arctic-draining river watersheds (Mackenzie, Ob, Lena and Yenisei; herein referred to as MOLY) are analyzed to identify historic changes in the magnitude and timing of freshwater input to the Arctic Ocean with emphasis on the spring freshet. Results show that the total freshwater influx to the Arctic Ocean increased by 89 km3/decade, amounting to a 14% increase during the 30-year period from 1980 to 2009. A distinct shift towards earlier melt timing is also indicated by proportional increases in fall, winter and spring discharges (by 2.5%, 1.3% and 2.5% respectively) followed by a decrease (by 5.8%) in summer discharge as a percentage of the mean annual flow. This seasonal increase in discharge and earlier pulse onset dates indicates a general shift towards a flatter, broad-based hydrograph with earlier peak discharges. The study also reveals that the increasing trend in freshwater discharge to the Arctic Ocean is not solely due to increased spring freshet discharge, but is a combination of increases in all seasons except that of the summer.\n
\n\n\n\n \n\n \n \n \n \n \n \n Efficiency of crustacean zooplankton in transferring allochthonous carbon in a boreal lake.\n \n \n \n \n\n\n \n Grosbois, G.; Vachon, D.; Giorgio, P. d.; and Rautio, M.\n\n\n \n\n\n\n Ecology, 101(6): e03013. February 2020.\n _eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.3013\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{grosbois_efficiency_2020,\n\ttitle = {Efficiency of crustacean zooplankton in transferring allochthonous carbon in a boreal lake},\n\tvolume = {101},\n\tissn = {1939-9170},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.3013},\n\tdoi = {10.1002/ecy.3013},\n\tabstract = {Increased incorporation of terrestrial organic matter (t-OM) into consumer biomass (allochthony) is believed to reduce growth capacity. In this study, we examined the relationship between crustacean zooplankton allochthony and production in a boreal lake that displays strong seasonal variability in t-OM inputs. Contrary to our hypotheses, we found no effect of allochthony on production at the community and the species levels. The high frequency seasonal sampling (time-for-space) allowed for estimating the efficiency of zooplankton in converting this external carbon source to growth. From the daily t-OM inputs in the lake (57 – 3027 kg C per day), the zooplankton community transferred 0.2\\% into biomass (0.01 – 2.36 kg C per day); this level was of the same magnitude as the carbon transfer efficiency for algal-derived carbon (0.4\\%). In the context of the boundless carbon cycle which integrates inland waters as a biologically active component of the terrestrial landscape, the use of the time-for-space approach for the quantifying of t-OM trophic transfer efficiency by zooplankton is a critical step toward a better understanding of the effects of increasing external carbon fluxes on pelagic food webs.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-03-19},\n\tjournal = {Ecology},\n\tauthor = {Grosbois, Guillaume and Vachon, Dominic and Giorgio, Paul del and Rautio, Milla},\n\tmonth = feb,\n\tyear = {2020},\n\tnote = {\\_eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecy.3013},\n\tkeywords = {\\#nosource, Allochthony, Cyclops scutifer, Daphnia, Leptodiaptomus minutus, allochtrophy, carbon transfer efficiency, seasonal pattern, secondary production, stable isotopes},\n\tpages = {e03013},\n}\n\n\n\n\n\n Increased incorporation of terrestrial organic matter (t-OM) into consumer biomass (allochthony) is believed to reduce growth capacity. In this study, we examined the relationship between crustacean zooplankton allochthony and production in a boreal lake that displays strong seasonal variability in t-OM inputs. Contrary to our hypotheses, we found no effect of allochthony on production at the community and the species levels. The high frequency seasonal sampling (time-for-space) allowed for estimating the efficiency of zooplankton in converting this external carbon source to growth. From the daily t-OM inputs in the lake (57 – 3027 kg C per day), the zooplankton community transferred 0.2% into biomass (0.01 – 2.36 kg C per day); this level was of the same magnitude as the carbon transfer efficiency for algal-derived carbon (0.4%). In the context of the boundless carbon cycle which integrates inland waters as a biologically active component of the terrestrial landscape, the use of the time-for-space approach for the quantifying of t-OM trophic transfer efficiency by zooplankton is a critical step toward a better understanding of the effects of increasing external carbon fluxes on pelagic food webs.\n
\n\n\n\n \n\n \n \n \n \n \n \n Reindeer trampling promotes vegetation changes in tundra heathlands: results from a simulation experiment.\n \n \n \n \n\n\n \n Egelkraut, D.; Barthelemy, H.; and Olofsson, J.\n\n\n \n\n\n\n Journal of Vegetation Science, 31(3): 476–486. February 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.12871\n\n\n\n
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\n\n\n@article{egelkraut_reindeer_2020,\n\ttitle = {Reindeer trampling promotes vegetation changes in tundra heathlands: results from a simulation experiment.},\n\tvolume = {31},\n\tcopyright = {This article is protected by copyright. All rights reserved.},\n\tissn = {1654-1103},\n\tshorttitle = {Reindeer trampling promotes vegetation changes in tundra heathlands},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.12871},\n\tdoi = {10.1111/jvs.12871},\n\tabstract = {Question Herbivores exert strong influences on vegetation through activities such as trampling, defoliation, and fertilization. The combined effect of these activities on plant performance may cause dramatic vegetation shifts. Because herbivore pressures and the relative importance of their different activities are not equally distributed across the landscape, it is important to understand their isolated effect. One example of an herbivore-induced vegetation shift is the reindeer-driven transition from a subarctic tundra vegetation dominated by dwarf shrubs into a more productive, graminoid-dominated state. Here, we asked how each of the grazing activities by reindeer separately and combined, shape vegetation composition. Location Nordreisa, Norway. Methods We used a field experiment over six summers to study the separate and interacting effects of reindeer trampling, defoliation, feces addition and moss removal on tundra heath vegetation, and to identify which of these factors were most important in driving the plant community towards a graminoid-dominated state. Results The combination of all treatments resulted in the strongest vegetation changes, but trampling was the single most important factor altering the vegetation composition by reducing the abundance of both evergreen and deciduous dwarf shrubs. In contrast to what we expected, none of our treatments, separate or combined, resulted in an increased abundance of graminoids in five years, although such rapid vegetation changes have been observed in the field; in similar environmental conditions. Conclusions Trampling is the key process by which reindeer influence the abundance of functional groups, but only many processes combined result in strong changes in community composition. Moreover, additional factors not included in this experiment, such as urine, may be important in causing a state shift to a graminoid-dominated community.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-03-19},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Egelkraut, Dagmar and Barthelemy, Hélène and Olofsson, Johan},\n\tmonth = feb,\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.12871},\n\tkeywords = {\\#nosource, Defoliation, Rangifer tarandus, fertilization, grazing simulation, herbivory, shrubification, trampling, vegetation shifts},\n\tpages = {476--486},\n}\n\n\n\n\n\n Question Herbivores exert strong influences on vegetation through activities such as trampling, defoliation, and fertilization. The combined effect of these activities on plant performance may cause dramatic vegetation shifts. Because herbivore pressures and the relative importance of their different activities are not equally distributed across the landscape, it is important to understand their isolated effect. One example of an herbivore-induced vegetation shift is the reindeer-driven transition from a subarctic tundra vegetation dominated by dwarf shrubs into a more productive, graminoid-dominated state. Here, we asked how each of the grazing activities by reindeer separately and combined, shape vegetation composition. Location Nordreisa, Norway. Methods We used a field experiment over six summers to study the separate and interacting effects of reindeer trampling, defoliation, feces addition and moss removal on tundra heath vegetation, and to identify which of these factors were most important in driving the plant community towards a graminoid-dominated state. Results The combination of all treatments resulted in the strongest vegetation changes, but trampling was the single most important factor altering the vegetation composition by reducing the abundance of both evergreen and deciduous dwarf shrubs. In contrast to what we expected, none of our treatments, separate or combined, resulted in an increased abundance of graminoids in five years, although such rapid vegetation changes have been observed in the field; in similar environmental conditions. Conclusions Trampling is the key process by which reindeer influence the abundance of functional groups, but only many processes combined result in strong changes in community composition. Moreover, additional factors not included in this experiment, such as urine, may be important in causing a state shift to a graminoid-dominated community.\n
\n\n\n\n \n\n \n \n \n \n \n \n Habitat patchiness, ecological connectivity and the uneven recovery of boreal stream ecosystems from an experimental drought.\n \n \n \n \n\n\n \n Truchy, A.; Sarremejane, R.; Muotka, T.; Mykrä, H.; Angeler, D. G.; Lehosmaa, K.; Huusko, A.; Johnson, R. K.; Sponseller, R. A.; and McKie, B. G.\n\n\n \n\n\n\n Global Change Biology, 26(6): 3455–3472. March 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15063\n\n\n\n
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\n\n\n@article{truchy_habitat_2020,\n\ttitle = {Habitat patchiness, ecological connectivity and the uneven recovery of boreal stream ecosystems from an experimental drought},\n\tvolume = {26},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15063},\n\tdoi = {10.1111/gcb.15063},\n\tabstract = {Ongoing climate change is increasing the occurrence and intensity of drought episodes worldwide, including in boreal regions not previously regarded as drought prone, and where the impacts of drought remain poorly understood. Ecological connectivity is one factor that might influence community structure and ecosystem functioning post drought, by facilitating the recovery of sensitive species via dispersal at both local (e.g. a nearby habitat patch) and regional (from other systems within the same region) scales. In an outdoor mesocosm experiment, we investigated how impacts of drought on boreal stream ecosystems are altered by the spatial arrangement of local habitat patches within stream channels, and variation in ecological connectivity with a regional species pool. We measured basal ecosystem processes underlying carbon and nutrient cycling: (i) algal biomass accrual, (ii) microbial respiration and (iii) decomposition of organic matter, and sampled communities of aquatic fungi and benthic invertebrates. An eight-day drought event had strong impacts on both community structure and ecosystem functioning, including algal accrual, leaf decomposition and microbial respiration, with many of these impacts persisting even after water levels had been restored for 3.5 weeks. Enhanced connectivity with the regional species pool and increased aggregation of habitat patches also affected multiple response variables, especially those associated with microbes, and in some cases reduced the effects of drought to a small extent. This indicates that spatial processes might play a role in the resilience of communities and ecosystem functioning, given enough time. These effects were however insufficient to facilitate significant recovery in algal growth before seasonal die-back began in autumn. The limited resilience of ecosystem functioning in our experiment suggests that even short-term droughts can have extended consequences for stream ecosystems in the world’s vast boreal region, and especially on the ecosystem processes and services mediated by algal biofilms.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-03-18},\n\tjournal = {Global Change Biology},\n\tauthor = {Truchy, Amélie and Sarremejane, Romain and Muotka, Timo and Mykrä, Heikki and Angeler, David G. and Lehosmaa, Kaisa and Huusko, Ari and Johnson, Richard K. and Sponseller, Ryan A. and McKie, Brendan G.},\n\tmonth = mar,\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15063},\n\tkeywords = {\\#nosource, Algal production, Detritivores, Drought, Ecosystem processes, Habitat patch, Hyphomycete fungi, Meta-ecosystem, Spatial connectivity},\n\tpages = {3455--3472},\n}\n\n\n\n\n\n Ongoing climate change is increasing the occurrence and intensity of drought episodes worldwide, including in boreal regions not previously regarded as drought prone, and where the impacts of drought remain poorly understood. Ecological connectivity is one factor that might influence community structure and ecosystem functioning post drought, by facilitating the recovery of sensitive species via dispersal at both local (e.g. a nearby habitat patch) and regional (from other systems within the same region) scales. In an outdoor mesocosm experiment, we investigated how impacts of drought on boreal stream ecosystems are altered by the spatial arrangement of local habitat patches within stream channels, and variation in ecological connectivity with a regional species pool. We measured basal ecosystem processes underlying carbon and nutrient cycling: (i) algal biomass accrual, (ii) microbial respiration and (iii) decomposition of organic matter, and sampled communities of aquatic fungi and benthic invertebrates. An eight-day drought event had strong impacts on both community structure and ecosystem functioning, including algal accrual, leaf decomposition and microbial respiration, with many of these impacts persisting even after water levels had been restored for 3.5 weeks. Enhanced connectivity with the regional species pool and increased aggregation of habitat patches also affected multiple response variables, especially those associated with microbes, and in some cases reduced the effects of drought to a small extent. This indicates that spatial processes might play a role in the resilience of communities and ecosystem functioning, given enough time. These effects were however insufficient to facilitate significant recovery in algal growth before seasonal die-back began in autumn. The limited resilience of ecosystem functioning in our experiment suggests that even short-term droughts can have extended consequences for stream ecosystems in the world’s vast boreal region, and especially on the ecosystem processes and services mediated by algal biofilms.\n
\n\n\n\n \n\n \n \n \n \n \n \n Microbial processing of plant remains is co-limited by multiple nutrients in global grasslands.\n \n \n \n \n\n\n \n Ochoa‐Hueso, R.; Borer, E. T.; Seabloom, E. W.; Hobbie, S. E.; Risch, A. C.; Collins, S. L.; Alberti, J.; Bahamonde, H. A.; Brown, C. S.; Caldeira, M. C.; Daleo, P.; Dickman, C. R.; Ebeling, A.; Eisenhauer, N.; Esch, E. H.; Eskelinen, A.; Fernández, V.; Güsewell, S.; Gutierrez‐Larruga, B.; Hofmockel, K.; Laungani, R.; Lind, E.; López, A.; McCulley, R. L.; Moore, J. L.; Peri, P. L.; Power, S. A.; Price, J. N.; Prober, S. M.; Roscher, C.; Sarneel, J. M.; Schütz, M.; Siebert, J.; Standish, R. J.; Ayuso, S. V.; Virtanen, R.; Wardle, G. M.; Wiehl, G.; Yahdjian, L.; and Zamin, T.\n\n\n \n\n\n\n Global Change Biology, 28(6): 4572–4582. June 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15146\n\n\n\n
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\n\n\n@article{ochoahueso_microbial_2020,\n\ttitle = {Microbial processing of plant remains is co-limited by multiple nutrients in global grasslands},\n\tvolume = {28},\n\tcopyright = {© 2020 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15146},\n\tdoi = {10.1111/gcb.15146},\n\tabstract = {Microbial processing of aggregate-unprotected organic matter inputs is key for soil fertility, long-term ecosystem carbon and nutrient sequestration and sustainable agriculture. We investigated the effects of adding multiple nutrients (nitrogen, phosphorus and potassium plus nine essential macro- and micro-nutrients) on decomposition and biochemical transformation of standard plant materials buried in 21 grasslands from four continents. Addition of multiple nutrients weakly but consistently increased decomposition and biochemical transformation of plant remains during the peak-season, concurrent with changes in microbial exoenzymatic activity. Higher mean annual precipitation and lower mean annual temperature were the main climatic drivers of higher decomposition rates, while biochemical transformation of plant remains was negatively related to temperature of the wettest quarter. Nutrients enhanced decomposition most at cool, high rainfall sites, indicating that in a warmer and drier future fertilized grassland soils will have an even more limited potential for microbial processing of plant remains.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-07-13},\n\tjournal = {Global Change Biology},\n\tauthor = {Ochoa‐Hueso, Raúl and Borer, Elizabeth T. and Seabloom, Eric W. and Hobbie, Sarah E. and Risch, Anita C. and Collins, Scott L. and Alberti, Juan and Bahamonde, Héctor A. and Brown, Cynthia S. and Caldeira, Maria C. and Daleo, Pedro and Dickman, Chris R. and Ebeling, Anne and Eisenhauer, Nico and Esch, Ellen H. and Eskelinen, Anu and Fernández, Victoria and Güsewell, Sabine and Gutierrez‐Larruga, Blanca and Hofmockel, Kirsten and Laungani, Ramesh and Lind, Eric and López, Andrea and McCulley, Rebecca L. and Moore, Joslin L. and Peri, Pablo L. and Power, Sally A. and Price, Jodi N. and Prober, Suzanne M. and Roscher, Christiane and Sarneel, Judith M. and Schütz, Martin and Siebert, Julia and Standish, Rachel J. and Ayuso, Sergio Velasco and Virtanen, Risto and Wardle, Glenda M. and Wiehl, Georg and Yahdjian, Laura and Zamin, Tara},\n\tmonth = jun,\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15146},\n\tkeywords = {\\#nosource, NutNet, carbon cycling and sequestration, decomposition, eutrophication, fertilization, microbial activity, nutrient (co-)limitation},\n\tpages = {4572--4582},\n}\n\n\n\n\n\n Microbial processing of aggregate-unprotected organic matter inputs is key for soil fertility, long-term ecosystem carbon and nutrient sequestration and sustainable agriculture. We investigated the effects of adding multiple nutrients (nitrogen, phosphorus and potassium plus nine essential macro- and micro-nutrients) on decomposition and biochemical transformation of standard plant materials buried in 21 grasslands from four continents. Addition of multiple nutrients weakly but consistently increased decomposition and biochemical transformation of plant remains during the peak-season, concurrent with changes in microbial exoenzymatic activity. Higher mean annual precipitation and lower mean annual temperature were the main climatic drivers of higher decomposition rates, while biochemical transformation of plant remains was negatively related to temperature of the wettest quarter. Nutrients enhanced decomposition most at cool, high rainfall sites, indicating that in a warmer and drier future fertilized grassland soils will have an even more limited potential for microbial processing of plant remains.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming.\n \n \n \n \n\n\n \n Keuper, F.; Wild, B.; Kummu, M.; Beer, C.; Blume-Werry, G.; Fontaine, S.; Gavazov, K.; Gentsch, N.; Guggenberger, G.; Hugelius, G.; Jalava, M.; Koven, C.; Krab, E. J.; Kuhry, P.; Monteux, S.; Richter, A.; Shahzad, T.; Weedon, J. T.; and Dorrepaal, E.\n\n\n \n\n\n\n Nature Geoscience, 13(8): 560–565. August 2020.\n Number: 8 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{keuper_carbon_2020,\n\ttitle = {Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming},\n\tvolume = {13},\n\tcopyright = {2020 The Author(s), under exclusive licence to Springer Nature Limited},\n\tissn = {1752-0908},\n\turl = {https://www.nature.com/articles/s41561-020-0607-0},\n\tdoi = {10.1038/s41561-020-0607-0},\n\tabstract = {As global temperatures continue to rise, a key uncertainty of climate projections is the microbial decomposition of vast organic carbon stocks in thawing permafrost soils. Decomposition rates can accelerate up to fourfold in the presence of plant roots, and this mechanism—termed the rhizosphere priming effect—may be especially relevant to thawing permafrost soils as rising temperatures also stimulate plant productivity in the Arctic. However, priming is currently not explicitly included in any model projections of future carbon losses from the permafrost area. Here, we combine high-resolution spatial and depth-resolved datasets of key plant and permafrost properties with empirical relationships of priming effects from living plants on microbial respiration. We show that rhizosphere priming amplifies overall soil respiration in permafrost-affected ecosystems by {\\textasciitilde}12\\%, which translates to a priming-induced absolute loss of {\\textasciitilde}40 Pg soil carbon from the northern permafrost area by 2100. Our findings highlight the need to include fine-scale ecological interactions in order to accurately predict large-scale greenhouse gas emissions, and suggest even tighter restrictions on the estimated 200 Pg anthropogenic carbon emission budget to keep global warming below 1.5 °C.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2020-08-31},\n\tjournal = {Nature Geoscience},\n\tauthor = {Keuper, Frida and Wild, Birgit and Kummu, Matti and Beer, Christian and Blume-Werry, Gesche and Fontaine, Sébastien and Gavazov, Konstantin and Gentsch, Norman and Guggenberger, Georg and Hugelius, Gustaf and Jalava, Mika and Koven, Charles and Krab, Eveline J. and Kuhry, Peter and Monteux, Sylvain and Richter, Andreas and Shahzad, Tanvir and Weedon, James T. and Dorrepaal, Ellen},\n\tmonth = aug,\n\tyear = {2020},\n\tnote = {Number: 8\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {560--565},\n}\n\n\n\n\n\n As global temperatures continue to rise, a key uncertainty of climate projections is the microbial decomposition of vast organic carbon stocks in thawing permafrost soils. Decomposition rates can accelerate up to fourfold in the presence of plant roots, and this mechanism—termed the rhizosphere priming effect—may be especially relevant to thawing permafrost soils as rising temperatures also stimulate plant productivity in the Arctic. However, priming is currently not explicitly included in any model projections of future carbon losses from the permafrost area. Here, we combine high-resolution spatial and depth-resolved datasets of key plant and permafrost properties with empirical relationships of priming effects from living plants on microbial respiration. We show that rhizosphere priming amplifies overall soil respiration in permafrost-affected ecosystems by ~12%, which translates to a priming-induced absolute loss of ~40 Pg soil carbon from the northern permafrost area by 2100. Our findings highlight the need to include fine-scale ecological interactions in order to accurately predict large-scale greenhouse gas emissions, and suggest even tighter restrictions on the estimated 200 Pg anthropogenic carbon emission budget to keep global warming below 1.5 °C.\n
\n\n\n\n \n\n \n \n \n \n \n \n Drivers of diffusive CH4 emissions from shallow subarctic lakes on daily to multi-year timescales.\n \n \n \n \n\n\n \n Jansen, J.; Thornton, B. F.; Cortés, A.; Snöälv, J.; Wik, M.; MacIntyre, S.; and Crill, P. M.\n\n\n \n\n\n\n Biogeosciences, 17(7): 1911–1932. April 2020.\n \n\n\n\n
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\n\n\n\n@article{jansen_drivers_2020,\n\ttitle = {Drivers of diffusive {CH4} emissions from shallow subarctic lakes on daily to multi-year timescales},\n\tvolume = {17},\n\tissn = {1726-4189},\n\turl = {https://www.biogeosciences.net/17/1911/2020/},\n\tdoi = {10.5194/bg-17-1911-2020},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2020-04-23},\n\tjournal = {Biogeosciences},\n\tauthor = {Jansen, Joachim and Thornton, Brett F. and Cortés, Alicia and Snöälv, Jo and Wik, Martin and MacIntyre, Sally and Crill, Patrick M.},\n\tmonth = apr,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {1911--1932},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Systematic microbial production of optically active dissolved organic matter in subarctic lake water.\n \n \n \n \n\n\n \n Berggren, M.; Gudasz, C.; Guillemette, F.; Hensgens, G.; Ye, L.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 65(5): 951–961. 2020.\n _eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11362\n\n\n\n
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\n\n\n@article{berggren_systematic_2020,\n\ttitle = {Systematic microbial production of optically active dissolved organic matter in subarctic lake water},\n\tvolume = {65},\n\tcopyright = {© 2019 Association for the Sciences of Limnology and Oceanography},\n\tissn = {1939-5590},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lno.11362},\n\tdoi = {10.1002/lno.11362},\n\tabstract = {The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20\\% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22\\% and 30\\%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2020-08-31},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Berggren, Martin and Gudasz, Cristian and Guillemette, Francois and Hensgens, Geert and Ye, Linlin and Karlsson, Jan},\n\tyear = {2020},\n\tnote = {\\_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11362},\n\tkeywords = {\\#nosource},\n\tpages = {951--961},\n}\n\n\n\n\n\n The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.\n
\n\n\n\n \n\n \n \n \n \n \n \n Autumn migration direction of juvenile willow warblers (Phylloscopus t. trochilus and P. t. acredula) and their hybrids assessed by qPCR SNP genotyping.\n \n \n \n \n\n\n \n Zhao, T.; Ilieva, M.; Larson, K.; Lundberg, M.; Neto, J. M.; Sokolovskis, K.; Åkesson, S.; and Bensch, S.\n\n\n \n\n\n\n Movement Ecology, 8(1): 22. May 2020.\n \n\n\n\n
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\n\n\n@article{zhao_autumn_2020,\n\ttitle = {Autumn migration direction of juvenile willow warblers ({Phylloscopus} t. trochilus and {P}. t. acredula) and their hybrids assessed by {qPCR} {SNP} genotyping},\n\tvolume = {8},\n\tissn = {2051-3933},\n\turl = {https://doi.org/10.1186/s40462-020-00209-7},\n\tdoi = {10.1186/s40462-020-00209-7},\n\tabstract = {Geographic regions, where two closely related taxa with different migration routes come into contact, are known as migratory divides. Hybrids originating from migratory divides are hypothesized to migrate intermediately relative to the parental populations. Few studies have tested this hypothesis in wild birds, and only in hybrids that have completed the migration back to the breeding grounds. Here, we make use of the well-established migration routes of willow warblers (Phylloscopus trochilus), for which the subspecies trochilus and acredula have migration-associated genetic markers on chromosomes 1 and 5. The genetic approach enabled us to analyze the geographic distribution of juveniles during their first autumn migration, predicting that hybrids should be more frequent in the central flyway over Italy than along the typical SW routes of trochilus and SE routes of acredula.},\n\tnumber = {1},\n\turldate = {2020-06-08},\n\tjournal = {Movement Ecology},\n\tauthor = {Zhao, Tianhao and Ilieva, Mihaela and Larson, Keith and Lundberg, Max and Neto, Júlio M. and Sokolovskis, Kristaps and Åkesson, Susanne and Bensch, Staffan},\n\tmonth = may,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {22},\n}\n\n\n\n\n\n Geographic regions, where two closely related taxa with different migration routes come into contact, are known as migratory divides. Hybrids originating from migratory divides are hypothesized to migrate intermediately relative to the parental populations. Few studies have tested this hypothesis in wild birds, and only in hybrids that have completed the migration back to the breeding grounds. Here, we make use of the well-established migration routes of willow warblers (Phylloscopus trochilus), for which the subspecies trochilus and acredula have migration-associated genetic markers on chromosomes 1 and 5. The genetic approach enabled us to analyze the geographic distribution of juveniles during their first autumn migration, predicting that hybrids should be more frequent in the central flyway over Italy than along the typical SW routes of trochilus and SE routes of acredula.\n
\n\n\n\n \n\n \n \n \n \n \n \n Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw.\n \n \n \n \n\n\n \n Hugelius, G.; Loisel, J.; Chadburn, S.; Jackson, R. B.; Jones, M.; MacDonald, G.; Marushchak, M.; Olefeldt, D.; Packalen, M.; Siewert, M. B.; Treat, C.; Turetsky, M.; Voigt, C.; and Yu, Z.\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences, 117(34): 20438–20446. August 2020.\n Publisher: National Academy of Sciences Section: Physical Sciences\n\n\n\n
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\n\n\n@article{hugelius_large_2020,\n\ttitle = {Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw},\n\tvolume = {117},\n\tcopyright = {Copyright © 2020 the Author(s). Published by PNAS.. https://creativecommons.org/licenses/by/4.0/This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY).},\n\tissn = {0027-8424, 1091-6490},\n\turl = {https://www.pnas.org/content/117/34/20438},\n\tdoi = {10.1073/pnas.1916387117},\n\tabstract = {Northern peatlands have accumulated large stocks of organic carbon (C) and nitrogen (N), but their spatial distribution and vulnerability to climate warming remain uncertain. Here, we used machine-learning techniques with extensive peat core data (n {\\textgreater} 7,000) to create observation-based maps of northern peatland C and N stocks, and to assess their response to warming and permafrost thaw. We estimate that northern peatlands cover 3.7 ± 0.5 million km2 and store 415 ± 150 Pg C and 10 ± 7 Pg N. Nearly half of the peatland area and peat C stocks are permafrost affected. Using modeled global warming stabilization scenarios (from 1.5 to 6 °C warming), we project that the current sink of atmospheric C (0.10 ± 0.02 Pg C⋅y−1) in northern peatlands will shift to a C source as 0.8 to 1.9 million km2 of permafrost-affected peatlands thaw. The projected thaw would cause peatland greenhouse gas emissions equal to ∼1\\% of anthropogenic radiative forcing in this century. The main forcing is from methane emissions (0.7 to 3 Pg cumulative CH4-C) with smaller carbon dioxide forcing (1 to 2 Pg CO2-C) and minor nitrous oxide losses. We project that initial CO2-C losses reverse after ∼200 y, as warming strengthens peatland C-sinks. We project substantial, but highly uncertain, additional losses of peat into fluvial systems of 10 to 30 Pg C and 0.4 to 0.9 Pg N. The combined gaseous and fluvial peatland C loss estimated here adds 30 to 50\\% onto previous estimates of permafrost-thaw C losses, with southern permafrost regions being the most vulnerable.},\n\tlanguage = {en},\n\tnumber = {34},\n\turldate = {2020-10-08},\n\tjournal = {Proceedings of the National Academy of Sciences},\n\tauthor = {Hugelius, Gustaf and Loisel, Julie and Chadburn, Sarah and Jackson, Robert B. and Jones, Miriam and MacDonald, Glen and Marushchak, Maija and Olefeldt, David and Packalen, Maara and Siewert, Matthias B. and Treat, Claire and Turetsky, Merritt and Voigt, Carolina and Yu, Zicheng},\n\tmonth = aug,\n\tyear = {2020},\n\tpmid = {32778585},\n\tnote = {Publisher: National Academy of Sciences\nSection: Physical Sciences},\n\tkeywords = {\\#nosource, carbon stocks, greenhouse gas fluxes, nitrogen stocks, northern peatlands, permafrost thaw},\n\tpages = {20438--20446},\n}\n\n\n\n\n\n Northern peatlands have accumulated large stocks of organic carbon (C) and nitrogen (N), but their spatial distribution and vulnerability to climate warming remain uncertain. Here, we used machine-learning techniques with extensive peat core data (n \\textgreater 7,000) to create observation-based maps of northern peatland C and N stocks, and to assess their response to warming and permafrost thaw. We estimate that northern peatlands cover 3.7 ± 0.5 million km2 and store 415 ± 150 Pg C and 10 ± 7 Pg N. Nearly half of the peatland area and peat C stocks are permafrost affected. Using modeled global warming stabilization scenarios (from 1.5 to 6 °C warming), we project that the current sink of atmospheric C (0.10 ± 0.02 Pg C⋅y−1) in northern peatlands will shift to a C source as 0.8 to 1.9 million km2 of permafrost-affected peatlands thaw. The projected thaw would cause peatland greenhouse gas emissions equal to ∼1% of anthropogenic radiative forcing in this century. The main forcing is from methane emissions (0.7 to 3 Pg cumulative CH4-C) with smaller carbon dioxide forcing (1 to 2 Pg CO2-C) and minor nitrous oxide losses. We project that initial CO2-C losses reverse after ∼200 y, as warming strengthens peatland C-sinks. We project substantial, but highly uncertain, additional losses of peat into fluvial systems of 10 to 30 Pg C and 0.4 to 0.9 Pg N. The combined gaseous and fluvial peatland C loss estimated here adds 30 to 50% onto previous estimates of permafrost-thaw C losses, with southern permafrost regions being the most vulnerable.\n
\n\n\n\n \n\n \n \n \n \n \n \n Particles and aeration at mire-stream interfaces cause selective removal and modification of dissolved organic matter.\n \n \n \n \n\n\n \n Einarsdóttir, K.; Attermeyer, K.; Hawkes, J. A.; Kothawala, D.; Sponseller, R. A.; and Tranvik, L. J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, n/a(n/a): e2020JG005654. 2020.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005654\n\n\n\n
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\n\n\n@article{einarsdottir_particles_2020,\n\ttitle = {Particles and aeration at mire-stream interfaces cause selective removal and modification of dissolved organic matter},\n\tvolume = {n/a},\n\tcopyright = {This article is protected by copyright. All rights reserved.},\n\tissn = {2169-8961},\n\turl = {http://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005654},\n\tdoi = {10.1029/2020jg005654},\n\tabstract = {Peatlands are dominant sources of dissolved organic matter (DOM) to boreal inland waters and play important roles in the aquatic carbon cycle. Yet, before peat-derived DOM enters aquatic networks, it needs to pass through peat-stream interfaces that are often characterized by transitions from anoxic or hypoxic to oxic conditions. Aeration at these interfaces may trigger processes that impact the DOM pool, and its fate downstream. Here, we experimentally assessed how the aeration of iron- and organic-rich mire-waters influences biodegradation, particle-formation, and modification of DOM. In addition, we investigated how suspended peat-derived particles from mires may influence these processes. We found that within five days of aeration, 20\\% of the DOM transformed into particulate organic matter (POM). This removal was likely due to combination of mechanisms including co-precipitation with oxidized iron, aggregation, and DOM-adsorption onto peat-derived particles. Peat-derived particles promoted microbial activity, but biodegradation was a minor loss mechanism of DOM removal. Interestingly, microbial respiration accounted for only half of the oxygen loss, suggesting substantial non-respiratory oxygen consumption. The differences observed in DOM characteristics between anoxic and aerated treatments suggest that hydrophilic, aromatic DOM co-precipitated with iron oxides in aerated samples, and the corresponding C:N analysis of generated POM revealed that these organic species were nitrogen-poor. Meanwhile, POM formed via adsorption onto peat-derived particles generated from non-aromatic DOM and more nitrogen-rich species. Hence, selective removal of DOM, dissolved iron, and thus oxygen may be important and overlooked processes in mire-dominated headwater systems.},\n\tlanguage = {en},\n\tnumber = {n/a},\n\turldate = {2020-11-20},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Einarsdóttir, Karólína and Attermeyer, Katrin and Hawkes, Jeffrey A. and Kothawala, Dolly and Sponseller, Ryan A. and Tranvik, Lars J.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005654},\n\tkeywords = {\\#nosource, CN, Co-precipitation, DOM, Iron, POM, Particle adsorption},\n\tpages = {e2020JG005654},\n}\n\n\n\n\n\n Peatlands are dominant sources of dissolved organic matter (DOM) to boreal inland waters and play important roles in the aquatic carbon cycle. Yet, before peat-derived DOM enters aquatic networks, it needs to pass through peat-stream interfaces that are often characterized by transitions from anoxic or hypoxic to oxic conditions. Aeration at these interfaces may trigger processes that impact the DOM pool, and its fate downstream. Here, we experimentally assessed how the aeration of iron- and organic-rich mire-waters influences biodegradation, particle-formation, and modification of DOM. In addition, we investigated how suspended peat-derived particles from mires may influence these processes. We found that within five days of aeration, 20% of the DOM transformed into particulate organic matter (POM). This removal was likely due to combination of mechanisms including co-precipitation with oxidized iron, aggregation, and DOM-adsorption onto peat-derived particles. Peat-derived particles promoted microbial activity, but biodegradation was a minor loss mechanism of DOM removal. Interestingly, microbial respiration accounted for only half of the oxygen loss, suggesting substantial non-respiratory oxygen consumption. The differences observed in DOM characteristics between anoxic and aerated treatments suggest that hydrophilic, aromatic DOM co-precipitated with iron oxides in aerated samples, and the corresponding C:N analysis of generated POM revealed that these organic species were nitrogen-poor. Meanwhile, POM formed via adsorption onto peat-derived particles generated from non-aromatic DOM and more nitrogen-rich species. Hence, selective removal of DOM, dissolved iron, and thus oxygen may be important and overlooked processes in mire-dominated headwater systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Emission of Greenhouse Gases From Water Tracks Draining Arctic Hillslopes.\n \n \n \n \n\n\n \n Harms, T. K.; Rocher‐Ros, G.; and Godsey, S. E.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 125(12): e2020JG005889. 2020.\n _eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005889\n\n\n\n
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\n\n\n@article{harms_emission_2020,\n\ttitle = {Emission of {Greenhouse} {Gases} {From} {Water} {Tracks} {Draining} {Arctic} {Hillslopes}},\n\tvolume = {125},\n\tcopyright = {©2020. American Geophysical Union. All Rights Reserved.},\n\tissn = {2169-8961},\n\turl = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005889},\n\tdoi = {10.1029/2020jg005889},\n\tabstract = {Experimental and ambient warming of Arctic tundra results in emissions of greenhouse gases to the atmosphere, contributing to a positive feedback to climate warming. Estimates of gas emissions from lakes and terrestrial tundra confirm the significance of aquatic fluxes in greenhouse gas budgets, whereas few estimates describe emissions from fluvial networks. We measured dissolved gas concentrations and estimated emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from water tracks, vegetated depressions that hydrologically connect hillslope soils to lakes and streams. Concentrations of trace gases generally increased as ground thaw deepened through the growing season, indicating active production of greenhouse gases in thawed soils. Wet antecedent conditions were correlated with a decline in CO2 and CH4 concentrations. Dissolved N2O in excess of atmospheric equilibrium occurred in drier water tracks, but on average water tracks took up N2O from the atmosphere at low rates. Estimated CO2 emission rates for water tracks were among the highest observed for Arctic aquatic ecosystems, whereas CH4 emissions were of similar magnitude to streams. Despite occupying less than 1\\% of total catchment area, surface waters within water tracks were an estimated source of up to 53–85\\% of total CH4 emissions from their catchments and offset the terrestrial C sink by 5–9\\% during the growing season. Water tracks are abundant features of tundra landscapes that contain warmer soils and incur deeper thaw than adjacent terrestrial ecosystems and as such might contribute to ongoing and accelerating release of greenhouse gases from permafrost soils to the atmosphere.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2021-01-18},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Harms, Tamara K. and Rocher‐Ros, Gerard and Godsey, Sarah E.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005889},\n\tkeywords = {\\#nosource, carbon dioxide (CO2), dissolved gases, flow paths, methane (CH4), nitrous oxide (N2O), tundra},\n\tpages = {e2020JG005889},\n}\n\n\n\n\n\n Experimental and ambient warming of Arctic tundra results in emissions of greenhouse gases to the atmosphere, contributing to a positive feedback to climate warming. Estimates of gas emissions from lakes and terrestrial tundra confirm the significance of aquatic fluxes in greenhouse gas budgets, whereas few estimates describe emissions from fluvial networks. We measured dissolved gas concentrations and estimated emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from water tracks, vegetated depressions that hydrologically connect hillslope soils to lakes and streams. Concentrations of trace gases generally increased as ground thaw deepened through the growing season, indicating active production of greenhouse gases in thawed soils. Wet antecedent conditions were correlated with a decline in CO2 and CH4 concentrations. Dissolved N2O in excess of atmospheric equilibrium occurred in drier water tracks, but on average water tracks took up N2O from the atmosphere at low rates. Estimated CO2 emission rates for water tracks were among the highest observed for Arctic aquatic ecosystems, whereas CH4 emissions were of similar magnitude to streams. Despite occupying less than 1% of total catchment area, surface waters within water tracks were an estimated source of up to 53–85% of total CH4 emissions from their catchments and offset the terrestrial C sink by 5–9% during the growing season. Water tracks are abundant features of tundra landscapes that contain warmer soils and incur deeper thaw than adjacent terrestrial ecosystems and as such might contribute to ongoing and accelerating release of greenhouse gases from permafrost soils to the atmosphere.\n
\n\n\n\n \n\n \n \n \n \n \n \n Variables Affecting Resource Subsidies from Streams and Rivers to Land and their Susceptibility to Global Change Stressors.\n \n \n \n \n\n\n \n Muehlbauer, J. D.; Larsen, S.; Jonsson, M.; and Emilson, E. J. S.\n\n\n \n\n\n\n In Kraus, J. M.; Walters, D. M.; and Mills, M. A., editor(s), Contaminants and Ecological Subsidies: The Land-Water Interface, pages 129–155. Springer International Publishing, Cham, 2020.\n \n\n\n\n
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\n\n\n@incollection{muehlbauer_variables_2020,\n\taddress = {Cham},\n\ttitle = {Variables {Affecting} {Resource} {Subsidies} from {Streams} and {Rivers} to {Land} and their {Susceptibility} to {Global} {Change} {Stressors}},\n\tisbn = {978-3-030-49480-3},\n\turl = {https://doi.org/10.1007/978-3-030-49480-3_7},\n\tabstract = {Stream and river ecosystems provide subsidies of emergent adult aquatic insects and other resources to terrestrial food webs, and this lotic–land subsidy has garnered much attention in recent research. Here, we critically examine a list of biotic and abiotic variables—including productivity, dominant taxa, geomorphology, and weather—that should be important in affecting the nature of these subsidy dynamics between lotic and terrestrial ecosystems, especially the pathway from emergent aquatic insects to terrestrial predators. We also explore how interactions between these variables can lead to otherwise unexpected patterns in the importance of aquatic subsidies to terrestrial food webs. Utilizing a match-mismatch framework developed previously, we identify how these variables and interactions may be affected by a broad suite of stressors in addition to contaminants: climate change, land-use conversion, damming and water abstraction, and species invasions and extinctions. These stressors may all act to modify and potentially exacerbate the effects of contaminants on subsidies. The available literature on many variables is sparse, despite strong theoretical underpinnings supporting their importance for lotic–land subsidies. Notably, these understudied variables include those related to physical geomorphology and the structure of the stream/river and floodplain/riparian zone as well as species-specific interactions between aquatic and terrestrial organisms. We suggest that more explicit characterization of these variables and more research directly linking broad-scale stressors to subsidy resource–consumer interactions can help provide a more mechanistic understanding to lotic–land subsidy dynamics within a changing environment.},\n\tlanguage = {en},\n\turldate = {2020-11-20},\n\tbooktitle = {Contaminants and {Ecological} {Subsidies}: {The} {Land}-{Water} {Interface}},\n\tpublisher = {Springer International Publishing},\n\tauthor = {Muehlbauer, Jeffrey D. and Larsen, Stefano and Jonsson, Micael and Emilson, Erik J. S.},\n\teditor = {Kraus, Johanna M. and Walters, David M. and Mills, Marc A.},\n\tyear = {2020},\n\tdoi = {10.1007/978-3-030-49480-3_7},\n\tkeywords = {\\#nosource, Climate change, Dams, Freshwater subsidies, Invasive species, Land use, Stressors},\n\tpages = {129--155},\n}\n\n\n\n\n\n Stream and river ecosystems provide subsidies of emergent adult aquatic insects and other resources to terrestrial food webs, and this lotic–land subsidy has garnered much attention in recent research. Here, we critically examine a list of biotic and abiotic variables—including productivity, dominant taxa, geomorphology, and weather—that should be important in affecting the nature of these subsidy dynamics between lotic and terrestrial ecosystems, especially the pathway from emergent aquatic insects to terrestrial predators. We also explore how interactions between these variables can lead to otherwise unexpected patterns in the importance of aquatic subsidies to terrestrial food webs. Utilizing a match-mismatch framework developed previously, we identify how these variables and interactions may be affected by a broad suite of stressors in addition to contaminants: climate change, land-use conversion, damming and water abstraction, and species invasions and extinctions. These stressors may all act to modify and potentially exacerbate the effects of contaminants on subsidies. The available literature on many variables is sparse, despite strong theoretical underpinnings supporting their importance for lotic–land subsidies. Notably, these understudied variables include those related to physical geomorphology and the structure of the stream/river and floodplain/riparian zone as well as species-specific interactions between aquatic and terrestrial organisms. We suggest that more explicit characterization of these variables and more research directly linking broad-scale stressors to subsidy resource–consumer interactions can help provide a more mechanistic understanding to lotic–land subsidy dynamics within a changing environment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon and nitrogen cycling in Yedoma permafrost controlled by microbial functional limitations.\n \n \n \n \n\n\n \n Monteux, S.; Keuper, F.; Fontaine, S.; Gavazov, K.; Hallin, S.; Juhanson, J.; Krab, E. J.; Revaillot, S.; Verbruggen, E.; Walz, J.; Weedon, J. T.; and Dorrepaal, E.\n\n\n \n\n\n\n Nature Geoscience, 13(12): 794–798. December 2020.\n Number: 12 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{monteux_carbon_2020,\n\ttitle = {Carbon and nitrogen cycling in {Yedoma} permafrost controlled by microbial functional limitations},\n\tvolume = {13},\n\tcopyright = {2020 The Author(s), under exclusive licence to Springer Nature Limited},\n\tissn = {1752-0908},\n\turl = {http://www.nature.com/articles/s41561-020-00662-4},\n\tdoi = {10.1038/s41561-020-00662-4},\n\tabstract = {Warming-induced microbial decomposition of organic matter in permafrost soils constitutes a climate-change feedback of uncertain magnitude. While physicochemical constraints on soil functioning are relatively well understood, the constraints attributable to microbial community composition remain unclear. Here we show that biogeochemical processes in permafrost can be impaired by missing functions in the microbial community—functional limitations—probably due to environmental filtering of the microbial community over millennia-long freezing. We inoculated Yedoma permafrost with a functionally diverse exogenous microbial community to test this mechanism by introducing potentially missing microbial functions. This initiated nitrification activity and increased CO2 production by 38\\% over 161 days. The changes in soil functioning were strongly associated with an altered microbial community composition, rather than with changes in soil chemistry or microbial biomass. The present permafrost microbial community composition thus constrains carbon and nitrogen biogeochemical processes, but microbial colonization, likely to occur upon permafrost thaw in situ, can alleviate such functional limitations. Accounting for functional limitations and their alleviation could strongly increase our estimate of the vulnerability of permafrost soil organic matter to decomposition and the resulting global climate feedback.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2021-01-18},\n\tjournal = {Nature Geoscience},\n\tauthor = {Monteux, Sylvain and Keuper, Frida and Fontaine, Sébastien and Gavazov, Konstantin and Hallin, Sara and Juhanson, Jaanis and Krab, Eveline J. and Revaillot, Sandrine and Verbruggen, Erik and Walz, Josefine and Weedon, James T. and Dorrepaal, Ellen},\n\tmonth = dec,\n\tyear = {2020},\n\tnote = {Number: 12\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {794--798},\n}\n\n\n\n\n\n Warming-induced microbial decomposition of organic matter in permafrost soils constitutes a climate-change feedback of uncertain magnitude. While physicochemical constraints on soil functioning are relatively well understood, the constraints attributable to microbial community composition remain unclear. Here we show that biogeochemical processes in permafrost can be impaired by missing functions in the microbial community—functional limitations—probably due to environmental filtering of the microbial community over millennia-long freezing. We inoculated Yedoma permafrost with a functionally diverse exogenous microbial community to test this mechanism by introducing potentially missing microbial functions. This initiated nitrification activity and increased CO2 production by 38% over 161 days. The changes in soil functioning were strongly associated with an altered microbial community composition, rather than with changes in soil chemistry or microbial biomass. The present permafrost microbial community composition thus constrains carbon and nitrogen biogeochemical processes, but microbial colonization, likely to occur upon permafrost thaw in situ, can alleviate such functional limitations. Accounting for functional limitations and their alleviation could strongly increase our estimate of the vulnerability of permafrost soil organic matter to decomposition and the resulting global climate feedback.\n
\n\n\n\n \n\n \n \n \n \n \n \n Turbulence in a small boreal lake: Consequences for air–water gas exchange.\n \n \n \n \n\n\n \n MacIntyre, S.; Bastviken, D.; Arneborg, L.; Crowe, A. T.; Karlsson, J.; Andersson, A.; Gålfalk, M.; Rutgersson, A.; Podgrajsek, E.; and Melack, J. M.\n\n\n \n\n\n\n Limnology and Oceanography, n/a(n/a): 20. 2020.\n _eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11645\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{macintyre_turbulence_2020,\n\ttitle = {Turbulence in a small boreal lake: {Consequences} for air–water gas exchange},\n\tvolume = {n/a},\n\tissn = {1939-5590},\n\tshorttitle = {Turbulence in a small boreal lake},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lno.11645},\n\tdoi = {10.1002/lno.11645},\n\tabstract = {The hydrodynamics within small boreal lakes have rarely been studied, yet knowing whether turbulence at the air–water interface and in the water column scales with metrics developed elsewhere is essential for computing metabolism and fluxes of climate-forcing trace gases. We instrumented a humic, 4.7 ha, boreal lake with two meteorological stations, three thermistor arrays, an infrared (IR) camera to quantify surface divergence, obtained turbulence as dissipation rate of turbulent kinetic energy (ε) using an acoustic Doppler velocimeter and a temperature-gradient microstructure profiler, and conducted chamber measurements for short periods to obtain fluxes and gas transfer velocities (k). Near-surface ε varied from 10−8 to 10−6 m2 s−3 for the 0–4 m s−1 winds and followed predictions from Monin–Obukhov similarity theory. The coefficient of eddy diffusivity in the mixed layer was up to 10−3 m2 s−1 on the windiest afternoons, an order of magnitude less other afternoons, and near molecular at deeper depths. The upper thermocline upwelled when Lake numbers (LN) dropped below four facilitating vertical and horizontal exchange. k computed from a surface renewal model using ε agreed with values from chambers and surface divergence and increased linearly with wind speed. Diurnal thermoclines formed on sunny days when winds were {\\textless} 3 m s−1, a condition that can lead to elevated near-surface ε and k. Results extend scaling approaches developed in the laboratory and for larger water bodies, illustrate turbulence and k are greater than expected in small wind-sheltered lakes, and provide new equations to quantify fluxes.},\n\tlanguage = {en},\n\tnumber = {n/a},\n\turldate = {2021-01-18},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {MacIntyre, Sally and Bastviken, David and Arneborg, Lars and Crowe, Adam T. and Karlsson, Jan and Andersson, Andreas and Gålfalk, Magnus and Rutgersson, Anna and Podgrajsek, Eva and Melack, John M.},\n\tyear = {2020},\n\tnote = {\\_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11645},\n\tkeywords = {\\#nosource},\n\tpages = {20},\n}\n\n\n\n\n\n The hydrodynamics within small boreal lakes have rarely been studied, yet knowing whether turbulence at the air–water interface and in the water column scales with metrics developed elsewhere is essential for computing metabolism and fluxes of climate-forcing trace gases. We instrumented a humic, 4.7 ha, boreal lake with two meteorological stations, three thermistor arrays, an infrared (IR) camera to quantify surface divergence, obtained turbulence as dissipation rate of turbulent kinetic energy (ε) using an acoustic Doppler velocimeter and a temperature-gradient microstructure profiler, and conducted chamber measurements for short periods to obtain fluxes and gas transfer velocities (k). Near-surface ε varied from 10−8 to 10−6 m2 s−3 for the 0–4 m s−1 winds and followed predictions from Monin–Obukhov similarity theory. The coefficient of eddy diffusivity in the mixed layer was up to 10−3 m2 s−1 on the windiest afternoons, an order of magnitude less other afternoons, and near molecular at deeper depths. The upper thermocline upwelled when Lake numbers (LN) dropped below four facilitating vertical and horizontal exchange. k computed from a surface renewal model using ε agreed with values from chambers and surface divergence and increased linearly with wind speed. Diurnal thermoclines formed on sunny days when winds were \\textless 3 m s−1, a condition that can lead to elevated near-surface ε and k. Results extend scaling approaches developed in the laboratory and for larger water bodies, illustrate turbulence and k are greater than expected in small wind-sheltered lakes, and provide new equations to quantify fluxes.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Structure of Riparian Vegetation in Agricultural Landscapes Influences Spider Communities and Aquatic-Terrestrial Linkages.\n \n \n \n \n\n\n \n Ramberg, E.; Burdon, F. J.; Sargac, J.; Kupilas, B.; Rîşnoveanu, G.; Lau, D. C. P.; Johnson, R. K.; and McKie, B. G.\n\n\n \n\n\n\n Water, 12(10): 2855. October 2020.\n Number: 10 Publisher: Multidisciplinary Digital Publishing Institute\n\n\n\n
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\n\n\n@article{ramberg_structure_2020,\n\ttitle = {The {Structure} of {Riparian} {Vegetation} in {Agricultural} {Landscapes} {Influences} {Spider} {Communities} and {Aquatic}-{Terrestrial} {Linkages}},\n\tvolume = {12},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\turl = {https://www.mdpi.com/2073-4441/12/10/2855},\n\tdoi = {10.3390/w12102855},\n\tabstract = {Riparian habitats are important ecotones connecting aquatic and terrestrial ecosystems, but are often highly degraded by human activities. Riparian buffers might help support impacted riparian communities, and improve trophic connectivity. We sampled spider communities from riparian habitats in an agricultural catchment, and analyzed their polyunsaturated fatty acid (PUFA) content to quantify trophic connectivity. Specific PUFAs are exclusively produced by stream algae, and thus are used to track uptake of aquatic resources by terrestrial consumers. Riparian spiders were collected from 10 site pairs situated along agricultural streams, and from five forest sites (25 sites total). Each agricultural site pair comprised an unshaded site with predominantly herbaceous vegetation cover, and a second with a woody riparian buffer. Spider communities differed between site types, with web-building spiders dominating woody buffered sites and free-living spiders associated with more open habitats. PUFA concentrations were greatest overall in free-living spiders, but there was also evidence for increased PUFA uptake by some spider groups when a woody riparian buffer was present. Our results reveal the different roles of open and wooded riparian habitats in supporting terrestrial consumers and aquatic-terrestrial connectivity, and highlight the value of incorporating patches of woody vegetation within riparian networks in highly modified landscapes.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2020-11-20},\n\tjournal = {Water},\n\tauthor = {Ramberg, Ellinor and Burdon, Francis J. and Sargac, Jasmina and Kupilas, Benjamin and Rîşnoveanu, Geta and Lau, Danny C. P. and Johnson, Richard K. and McKie, Brendan G.},\n\tmonth = oct,\n\tyear = {2020},\n\tnote = {Number: 10\nPublisher: Multidisciplinary Digital Publishing Institute},\n\tkeywords = {\\#nosource, agriculture, ecotone, polyunsaturated fatty acids, riparian buffer, spiders, trophic connectivity},\n\tpages = {2855},\n}\n\n\n\n\n\n Riparian habitats are important ecotones connecting aquatic and terrestrial ecosystems, but are often highly degraded by human activities. Riparian buffers might help support impacted riparian communities, and improve trophic connectivity. We sampled spider communities from riparian habitats in an agricultural catchment, and analyzed their polyunsaturated fatty acid (PUFA) content to quantify trophic connectivity. Specific PUFAs are exclusively produced by stream algae, and thus are used to track uptake of aquatic resources by terrestrial consumers. Riparian spiders were collected from 10 site pairs situated along agricultural streams, and from five forest sites (25 sites total). Each agricultural site pair comprised an unshaded site with predominantly herbaceous vegetation cover, and a second with a woody riparian buffer. Spider communities differed between site types, with web-building spiders dominating woody buffered sites and free-living spiders associated with more open habitats. PUFA concentrations were greatest overall in free-living spiders, but there was also evidence for increased PUFA uptake by some spider groups when a woody riparian buffer was present. Our results reveal the different roles of open and wooded riparian habitats in supporting terrestrial consumers and aquatic-terrestrial connectivity, and highlight the value of incorporating patches of woody vegetation within riparian networks in highly modified landscapes.\n
\n\n\n\n \n\n \n \n \n \n \n \n The role of nutrients for stream ecosystem function in Arctic landscapes : drivers of productivity under environmental change.\n \n \n \n \n\n\n \n Myrstener, M.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2020.\n Publisher: Umeå universitet\n\n\n\n
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\n\n\n@phdthesis{myrstener_role_2020,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {The role of nutrients for stream ecosystem function in {Arctic} landscapes : drivers of productivity under environmental change},\n\tshorttitle = {The role of nutrients for stream ecosystem function in {Arctic} landscapes},\n\turl = {http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-177439},\n\tabstract = {Arctic and sub-Arctic freshwaters are currently experiencing substantial ecosystem changes due to the effects of global warming. Global warming effects on these freshwaters include increasing water ...},\n\tlanguage = {eng},\n\turldate = {2021-01-18},\n\tschool = {Umeå University},\n\tauthor = {Myrstener, Maria},\n\tcollaborator = {Sponseller, Ryan A. and Giesler, Reiner and Bergström, Ann-Kristin},\n\tyear = {2020},\n\tnote = {Publisher: Umeå universitet},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Arctic and sub-Arctic freshwaters are currently experiencing substantial ecosystem changes due to the effects of global warming. Global warming effects on these freshwaters include increasing water ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Large-scale retrieval of coloured dissolved organic matter in northern lakes using Sentinel-2 data.\n \n \n \n \n\n\n \n Al-Kharusi, E. S.; Tenenbaum, D. E.; Abdi, A. M.; Kutser, T.; Karlsson, J.; Bergström, A.; and Berggren, M.\n\n\n \n\n\n\n Remote Sensing, 12(1): 157. January 2020.\n \n\n\n\n
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\n\n\n@article{al-kharusi_large-scale_2020,\n\ttitle = {Large-scale retrieval of coloured dissolved organic matter in northern lakes using {Sentinel}-2 data},\n\tvolume = {12},\n\tissn = {2072-4292},\n\turl = {https://www.mdpi.com/2072-4292/12/1/157},\n\tdoi = {10.3390/rs12010157},\n\tabstract = {Owing to the significant societal value of inland water resources, there is a need for cost-effective monitoring of water quality on large scales. We tested the suitability of the recently launched Sentinel-2A to monitor a key water quality parameter, coloured dissolved organic matter (CDOM), in various types of lakes in northern Sweden. Values of a(420)CDOM (CDOM absorption at 420 nm wavelength) were obtained by analyzing water samples from 46 lakes in five districts across Sweden within an area of approximately 800 km2. We evaluated the relationships between a(420)CDOM and band ratios derived from Sentinel-2A Level-1C and Level-2A products. The band ratios B2/B3 (460 nm/560 nm) and B3/B5 (560 nm/705 nm) showed poor relationships with a(420)CDOM in Level-1C and 2A data both before and after the removal of outliers. However, there was a slightly stronger power relationship between the atmospherically-corrected B3/B4 ratio and a(420)CDOM (R2 = 0.28, n = 46), and this relationship was further improved (R2 = 0.65, n = 41) by removing observations affected by light haze and cirrus clouds. This study covered a wide range of lakes in different landscape settings and demonstrates the broad applicability of a(420)CDOM retrieval algorithms based on the B3/B4 ratio derived from Sentinel-2A.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-03-19},\n\tjournal = {Remote Sensing},\n\tauthor = {Al-Kharusi, Enass Said. and Tenenbaum, David E. and Abdi, Abdulhakim M. and Kutser, Tiit and Karlsson, Jan and Bergström, Ann-Kristin and Berggren, Martin},\n\tmonth = jan,\n\tyear = {2020},\n\tkeywords = {\\#nosource},\n\tpages = {157},\n}\n\n\n\n\n\n Owing to the significant societal value of inland water resources, there is a need for cost-effective monitoring of water quality on large scales. We tested the suitability of the recently launched Sentinel-2A to monitor a key water quality parameter, coloured dissolved organic matter (CDOM), in various types of lakes in northern Sweden. Values of a(420)CDOM (CDOM absorption at 420 nm wavelength) were obtained by analyzing water samples from 46 lakes in five districts across Sweden within an area of approximately 800 km2. We evaluated the relationships between a(420)CDOM and band ratios derived from Sentinel-2A Level-1C and Level-2A products. The band ratios B2/B3 (460 nm/560 nm) and B3/B5 (560 nm/705 nm) showed poor relationships with a(420)CDOM in Level-1C and 2A data both before and after the removal of outliers. However, there was a slightly stronger power relationship between the atmospherically-corrected B3/B4 ratio and a(420)CDOM (R2 = 0.28, n = 46), and this relationship was further improved (R2 = 0.65, n = 41) by removing observations affected by light haze and cirrus clouds. This study covered a wide range of lakes in different landscape settings and demonstrates the broad applicability of a(420)CDOM retrieval algorithms based on the B3/B4 ratio derived from Sentinel-2A.\n
\n\n\n\n \n\n \n \n \n \n \n \n Protection of permafrost soils from thawing by increasing herbivore density.\n \n \n \n \n\n\n \n Beer, C.; Zimov, N.; Olofsson, J.; Porada, P.; and Zimov, S.\n\n\n \n\n\n\n Scientific Reports, 10(1): 1–10. March 2020.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{beer_protection_2020,\n\ttitle = {Protection of permafrost soils from thawing by increasing herbivore density},\n\tvolume = {10},\n\tcopyright = {2020 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-020-60938-y},\n\tdoi = {10.1038/s41598-020-60938-y},\n\tabstract = {Climate change will cause a substantial future greenhouse gas release from warming and thawing permafrost-affected soils to the atmosphere enabling a positive feedback mechanism. Increasing the population density of big herbivores in northern high-latitude ecosystems will increase snow density and hence decrease the insulation strength of snow during winter. As a consequence, theoretically 80\\% of current permafrost-affected soils ({\\textless}10 m) is projected to remain until 2100 even when assuming a strong warming using the Representative Concentration Pathway 8.5. Importantly, permafrost temperature is estimated to remain below −4 °C on average after increasing herbivore population density. Such ecosystem management practices would be therefore theoretically an important additional climate change mitigation strategy. Our results also highlight the importance of new field experiments and observations, and the integration of fauna dynamics into complex Earth System models, in order to reliably project future ecosystem functions and climate.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-04-23},\n\tjournal = {Scientific Reports},\n\tauthor = {Beer, Christian and Zimov, Nikita and Olofsson, Johan and Porada, Philipp and Zimov, Sergey},\n\tmonth = mar,\n\tyear = {2020},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {1--10},\n}\n\n\n\n\n\n Climate change will cause a substantial future greenhouse gas release from warming and thawing permafrost-affected soils to the atmosphere enabling a positive feedback mechanism. Increasing the population density of big herbivores in northern high-latitude ecosystems will increase snow density and hence decrease the insulation strength of snow during winter. As a consequence, theoretically 80% of current permafrost-affected soils (\\textless10 m) is projected to remain until 2100 even when assuming a strong warming using the Representative Concentration Pathway 8.5. Importantly, permafrost temperature is estimated to remain below −4 °C on average after increasing herbivore population density. Such ecosystem management practices would be therefore theoretically an important additional climate change mitigation strategy. Our results also highlight the importance of new field experiments and observations, and the integration of fauna dynamics into complex Earth System models, in order to reliably project future ecosystem functions and climate.\n
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\n \n \n\n \n \n \n \n \n \n Consequences of lake and river ice loss on cultural ecosystem services.\n \n \n \n \n\n\n \n Knoll, L. B.; Sharma, S.; Denfeld, B. A.; Flaim, G.; Hori, Y.; Magnuson, J. J.; Straile, D.; and Weyhenmeyer, G. A.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 4(5): 119–131. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10116\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{knoll_consequences_2019,\n\ttitle = {Consequences of lake and river ice loss on cultural ecosystem services},\n\tvolume = {4},\n\tcopyright = {© 2019 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {2378-2242},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10116},\n\tdoi = {10.1002/lol2.10116},\n\tabstract = {People extensively use lakes and rivers covered by seasonal ice. Although ice cover duration has been declining over the past 150 years for Northern Hemisphere freshwaters, we know relatively little about how ice loss directly affects humans. Here, we synthesize the cultural ecosystem services (i.e., services that provide intangible or nonmaterial benefits) and associated benefits supported by inland ice. We also provide, for the first time, empirical examples that give quantitative evidence for a winter warming effect on a wide range of ice-related cultural ecosystem services and benefits. We show that in recent decades, warmer air temperatures delayed the opening date of winter ice roads and led to cancellations of spiritual ceremonies, outdoor ice skating races, and ice fishing tournaments. Additionally, our synthesis effort suggests unexploited data sets that allow for the use of integrative approaches to evaluate the interplay between inland ice loss and society.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Knoll, Lesley B. and Sharma, Sapna and Denfeld, Blaize A. and Flaim, Giovanna and Hori, Yukari and Magnuson, John J. and Straile, Dietmar and Weyhenmeyer, Gesa A.},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10116},\n\tkeywords = {\\#nosource},\n\tpages = {119--131},\n}\n\n\n\n\n\n People extensively use lakes and rivers covered by seasonal ice. Although ice cover duration has been declining over the past 150 years for Northern Hemisphere freshwaters, we know relatively little about how ice loss directly affects humans. Here, we synthesize the cultural ecosystem services (i.e., services that provide intangible or nonmaterial benefits) and associated benefits supported by inland ice. We also provide, for the first time, empirical examples that give quantitative evidence for a winter warming effect on a wide range of ice-related cultural ecosystem services and benefits. We show that in recent decades, warmer air temperatures delayed the opening date of winter ice roads and led to cancellations of spiritual ceremonies, outdoor ice skating races, and ice fishing tournaments. Additionally, our synthesis effort suggests unexploited data sets that allow for the use of integrative approaches to evaluate the interplay between inland ice loss and society.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant functional types and temperature control carbon input via roots in peatland soils.\n \n \n \n \n\n\n \n Zeh, L.; Limpens, J.; Erhagen, B.; Bragazza, L.; and Kalbitz, K.\n\n\n \n\n\n\n Plant and Soil, 438(1): 19–38. May 2019.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{zeh_plant_2019,\n\ttitle = {Plant functional types and temperature control carbon input via roots in peatland soils},\n\tvolume = {438},\n\tissn = {1573-5036},\n\turl = {https://doi.org/10.1007/s11104-019-03958-6},\n\tdoi = {10.1007/s11104-019-03958-6},\n\tabstract = {Northern peatlands store large amounts of soil organic carbon (C) that can be very sensitive to ongoing global warming. Recently it has been shown that temperature-enhanced growth of vascular plants in these typically moss-dominated ecosystems may promote microbial peat decomposition by increased C input via root exudates. To what extent different plant functional types (PFT) and soil temperature interact in controlling root C input is still unclear. In this study we explored how root C input is related to the presence of ericoid shrubs (shrubs) and graminoid sedges (sedges) by means of a factorial plant clipping experiment (= PFT effect) in two peatlands located at different altitude (= temperature effect).},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Plant and Soil},\n\tauthor = {Zeh, Lilli and Limpens, Juul and Erhagen, Björn and Bragazza, Luca and Kalbitz, Karsten},\n\tmonth = may,\n\tyear = {2019},\n\tkeywords = {\\#nosource, Dissolved organic carbon, Peatland, Root carbon input, Sedges, Shrubs, Soil respiration, Vascular plants, δ 13C},\n\tpages = {19--38},\n}\n\n\n\n\n\n Northern peatlands store large amounts of soil organic carbon (C) that can be very sensitive to ongoing global warming. Recently it has been shown that temperature-enhanced growth of vascular plants in these typically moss-dominated ecosystems may promote microbial peat decomposition by increased C input via root exudates. To what extent different plant functional types (PFT) and soil temperature interact in controlling root C input is still unclear. In this study we explored how root C input is related to the presence of ericoid shrubs (shrubs) and graminoid sedges (sedges) by means of a factorial plant clipping experiment (= PFT effect) in two peatlands located at different altitude (= temperature effect).\n
\n\n\n\n \n\n \n \n \n \n \n \n Bottom-up and top-down effects of browning and warming on shallow lake food webs.\n \n \n \n \n\n\n \n Vasconcelos, F. R.; Diehl, S.; Rodríguez, P.; Hedström, P.; Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Global Change Biology, 25(2): 504–521. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14521\n\n\n\n
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\n\n\n@article{vasconcelos_bottom-up_2019,\n\ttitle = {Bottom-up and top-down effects of browning and warming on shallow lake food webs},\n\tvolume = {25},\n\tcopyright = {© 2018 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14521},\n\tdoi = {10.1111/gcb.14521},\n\tabstract = {Productivity and trophic structure of aquatic ecosystems result from a complex interplay of bottom-up and top-down forces that operate across benthic and pelagic food web compartments. Projected global changes urge the question how this interplay will be affected by browning (increasing input of terrestrial dissolved organic matter), nutrient enrichment and warming. We explored this with a process-based model of a shallow lake food web consisting of benthic and pelagic components (abiotic resources, primary producers, grazers, carnivores), and compared model expectations with the results of a browning and warming experiment in nutrient-poor ponds harboring a boreal lake community. Under low nutrient conditions, the model makes three major predictions. (a) Browning reduces light and increases nutrient supply; this decreases benthic and increases pelagic production, gradually shifting productivity from the benthic to the pelagic habitat. (b) Because of active habitat choice, fish exert top-down control on grazers and benefit primary producers primarily in the more productive of the two habitats. (c) Warming relaxes top-down control of grazers by fish and decreases primary producer biomass, but effects of warming are generally small compared to effects of browning and nutrient supply. Experimental results were consistent with most model predictions for browning: light penetration, benthic algal production, and zoobenthos biomass decreased, and pelagic nutrients and pelagic algal production increased with browning. Also consistent with expectations, warming had negative effects on benthic and pelagic algal biomass and weak effects on algal production and zoobenthos and zooplankton biomass. Inconsistent with expectations, browning had no effect on zooplankton and warming effects on fish depended on browning. The model is applicable also to nutrient-rich systems, and we propose that it is a useful tool for the exploration of the consequences of different climate change scenarios for productivity and food web dynamics in shallow lakes, the worldwide most common lake type.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Vasconcelos, Francisco Rivera and Diehl, Sebastian and Rodríguez, Patricia and Hedström, Per and Karlsson, Jan and Byström, Pär},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14521},\n\tkeywords = {\\#nosource, benthic and pelagic habitats, bottom-up and top-down control, browning, food webs, light and nutrients, shallow lake, top predator, warming},\n\tpages = {504--521},\n}\n\n\n\n\n\n Productivity and trophic structure of aquatic ecosystems result from a complex interplay of bottom-up and top-down forces that operate across benthic and pelagic food web compartments. Projected global changes urge the question how this interplay will be affected by browning (increasing input of terrestrial dissolved organic matter), nutrient enrichment and warming. We explored this with a process-based model of a shallow lake food web consisting of benthic and pelagic components (abiotic resources, primary producers, grazers, carnivores), and compared model expectations with the results of a browning and warming experiment in nutrient-poor ponds harboring a boreal lake community. Under low nutrient conditions, the model makes three major predictions. (a) Browning reduces light and increases nutrient supply; this decreases benthic and increases pelagic production, gradually shifting productivity from the benthic to the pelagic habitat. (b) Because of active habitat choice, fish exert top-down control on grazers and benefit primary producers primarily in the more productive of the two habitats. (c) Warming relaxes top-down control of grazers by fish and decreases primary producer biomass, but effects of warming are generally small compared to effects of browning and nutrient supply. Experimental results were consistent with most model predictions for browning: light penetration, benthic algal production, and zoobenthos biomass decreased, and pelagic nutrients and pelagic algal production increased with browning. Also consistent with expectations, warming had negative effects on benthic and pelagic algal biomass and weak effects on algal production and zoobenthos and zooplankton biomass. Inconsistent with expectations, browning had no effect on zooplankton and warming effects on fish depended on browning. The model is applicable also to nutrient-rich systems, and we propose that it is a useful tool for the exploration of the consequences of different climate change scenarios for productivity and food web dynamics in shallow lakes, the worldwide most common lake type.\n
\n\n\n\n \n\n \n \n \n \n \n \n Influence of water column stratification and mixing patterns on the fate of methane produced in deep sediments of a small eutrophic lake.\n \n \n \n \n\n\n \n Vachon, D.; Langenegger, T.; Donis, D.; and McGinnis, D. F.\n\n\n \n\n\n\n Limnology and Oceanography, 64(5): 2114–2128. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11172\n\n\n\n
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\n\n\n@article{vachon_influence_2019,\n\ttitle = {Influence of water column stratification and mixing patterns on the fate of methane produced in deep sediments of a small eutrophic lake},\n\tvolume = {64},\n\tcopyright = {© 2019 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11172},\n\tdoi = {10.1002/lno.11172},\n\tabstract = {Methane (CH4), a potent greenhouse gas, is produced in and emitted from lakes at globally significant rates. The drivers controlling the proportion of produced CH4 that will reach the atmosphere, however, are still not well understood. We sampled a small eutrophic lake (Soppensee, Switzerland) in 2016–2017 for CH4 concentrations profiles and emissions, combined with water column hydrodynamics to investigate the fate of CH4 produced in hypolimnetic sediments. Using a mass balance approach for the periods between April and October of both years, net CH4 production rates in hypolimnetic sediments ranged between 11.4 and 17.7 mmol m−2 d−1, of which 66–88\\% was stored in the hypolimnion, 13–27\\% was diffused to the epilimnion, and 6–7\\% left the sediments via ebullition. Combining these results with a process-based model we show that water column turbulent diffusivity (K z) had a major influence on the fate of produced CH4 in the sediments, where higher K z values potentially lead to greater proportion being oxidized and lower K z lead to a greater proportion being stored. During fall when the water column mixes, we found that a greater proportion of stored CH4 is emitted if the lake mixes rapidly, whereas a greater proportion will be oxidized if the water column mixes more gradually. This work highlights the central role of lake hydrodynamics in regulating CH4 dynamics and further suggests the potential for CH4 production and emissions to be sensitive to climate-driven alterations in lake mixing regimes and stratification.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Vachon, Dominic and Langenegger, Timon and Donis, Daphne and McGinnis, Daniel F.},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11172},\n\tkeywords = {\\#nosource},\n\tpages = {2114--2128},\n}\n\n\n\n\n\n Methane (CH4), a potent greenhouse gas, is produced in and emitted from lakes at globally significant rates. The drivers controlling the proportion of produced CH4 that will reach the atmosphere, however, are still not well understood. We sampled a small eutrophic lake (Soppensee, Switzerland) in 2016–2017 for CH4 concentrations profiles and emissions, combined with water column hydrodynamics to investigate the fate of CH4 produced in hypolimnetic sediments. Using a mass balance approach for the periods between April and October of both years, net CH4 production rates in hypolimnetic sediments ranged between 11.4 and 17.7 mmol m−2 d−1, of which 66–88% was stored in the hypolimnion, 13–27% was diffused to the epilimnion, and 6–7% left the sediments via ebullition. Combining these results with a process-based model we show that water column turbulent diffusivity (K z) had a major influence on the fate of produced CH4 in the sediments, where higher K z values potentially lead to greater proportion being oxidized and lower K z lead to a greater proportion being stored. During fall when the water column mixes, we found that a greater proportion of stored CH4 is emitted if the lake mixes rapidly, whereas a greater proportion will be oxidized if the water column mixes more gradually. This work highlights the central role of lake hydrodynamics in regulating CH4 dynamics and further suggests the potential for CH4 production and emissions to be sensitive to climate-driven alterations in lake mixing regimes and stratification.\n
\n\n\n\n \n\n \n \n \n \n \n \n Herbivore Effects on Ecosystem Process Rates in a Low-Productive System.\n \n \n \n \n\n\n \n Tuomi, M.; Stark, S.; Hoset, K. S.; Väisänen, M.; Oksanen, L.; Murguzur, F. J. A.; Tuomisto, H.; Dahlgren, J.; and Bråthen, K. A.\n\n\n \n\n\n\n Ecosystems, 22(4): 827–843. June 2019.\n \n\n\n\n
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\n\n\n@article{tuomi_herbivore_2019,\n\ttitle = {Herbivore {Effects} on {Ecosystem} {Process} {Rates} in a {Low}-{Productive} {System}},\n\tvolume = {22},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-018-0307-4},\n\tdoi = {10.1007/s10021-018-0307-4},\n\tabstract = {Mammalian herbivores shape the structure and function of many nutrient-limited or low-productive terrestrial ecosystems through modification of plant communities and plant–soil feedbacks. In the tundra biome, mammalian herbivores may both accelerate and decelerate plant biomass growth, microbial activity and nutrient cycling, that is, ecosystem process rates. Selective foraging and associated declines of palatable species are known to be major drivers of plant–soil feedbacks. However, declines in dominant plants of low palatability often linked with high herbivore densities may also modify ecosystem process rates, yet have received little attention. We present data from an island experiment with a 10-year vole density manipulation, to test the hypothesis that herbivores accelerate process rates by decreasing the relative abundance of poorly palatable plants to palatable ones. We measured plant species abundances and community composition, nitrogen contents of green plant tissues and multiple soil and litter variables under high and low vole density. Corroborating our hypothesis, periodic high vole density increased ecosystem process rates in low-productive tundra. High vole density was associated with both increasing relative abundance of palatable forbs over unpalatable evergreen dwarf shrubs and higher plant N content both at species and at community level. Changes in plant community composition, in turn, explained variation in microbial activity in litter and soil inorganic nutrient availability. We propose a new conceptual model with two distinct vole–plant–soil feedback pathways. Voles may drive local plant–soil feedbacks that either increase or decrease ecosystem process rates, in turn promoting heterogeneity in vegetation and soils across tundra landscapes.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Tuomi, Maria and Stark, Sari and Hoset, Katrine S. and Väisänen, Maria and Oksanen, Lauri and Murguzur, Francisco J. A. and Tuomisto, Hanna and Dahlgren, Jonas and Bråthen, Kari Anne},\n\tmonth = jun,\n\tyear = {2019},\n\tkeywords = {\\#nosource, NIRS, Northern Fennoscandia, dwarf shrub tundra, microbial activity, microtine rodent, plant community traits, plant–soil interactions, soil N and P},\n\tpages = {827--843},\n}\n\n\n\n\n\n Mammalian herbivores shape the structure and function of many nutrient-limited or low-productive terrestrial ecosystems through modification of plant communities and plant–soil feedbacks. In the tundra biome, mammalian herbivores may both accelerate and decelerate plant biomass growth, microbial activity and nutrient cycling, that is, ecosystem process rates. Selective foraging and associated declines of palatable species are known to be major drivers of plant–soil feedbacks. However, declines in dominant plants of low palatability often linked with high herbivore densities may also modify ecosystem process rates, yet have received little attention. We present data from an island experiment with a 10-year vole density manipulation, to test the hypothesis that herbivores accelerate process rates by decreasing the relative abundance of poorly palatable plants to palatable ones. We measured plant species abundances and community composition, nitrogen contents of green plant tissues and multiple soil and litter variables under high and low vole density. Corroborating our hypothesis, periodic high vole density increased ecosystem process rates in low-productive tundra. High vole density was associated with both increasing relative abundance of palatable forbs over unpalatable evergreen dwarf shrubs and higher plant N content both at species and at community level. Changes in plant community composition, in turn, explained variation in microbial activity in litter and soil inorganic nutrient availability. We propose a new conceptual model with two distinct vole–plant–soil feedback pathways. Voles may drive local plant–soil feedbacks that either increase or decrease ecosystem process rates, in turn promoting heterogeneity in vegetation and soils across tundra landscapes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra.\n \n \n \n \n\n\n \n Sitters, J.; Cherif, M.; Egelkraut, D.; Giesler, R.; and Olofsson, J.\n\n\n \n\n\n\n Functional Ecology, 33(7): 1233–1242. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.13342\n\n\n\n
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\n\n\n@article{sitters_long-term_2019,\n\ttitle = {Long-term heavy reindeer grazing promotes plant phosphorus limitation in arctic tundra},\n\tvolume = {33},\n\tcopyright = {© 2019 The Authors. Functional Ecology © 2019 British Ecological Society},\n\tissn = {1365-2435},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.13342},\n\tdoi = {10.1111/1365-2435.13342},\n\tabstract = {The potential of large mammalian herbivores to shift plant communities between nitrogen (N) and phosphorus (P) limitation has received little attention so far. However, herbivores can influence the cycling of these growth-limiting nutrients, and thereby affect plant nutrient limitation and productivity. Tundra ecosystems are nutrient-poor and commonly grazed by large herbivores like reindeer and may thus be responsive to such changes. Here, we examined the effect of long-term light and heavy reindeer grazing on nutrient limitation of plant growth in a Scandinavian arctic tundra. We are the first to conduct a factorial N and P fertilization experiment across the two grazing regimes in two functionally contrasting vegetation types: heath and meadow. Annual primary productivity (APP) showed contrasting responses to our fertilization treatments under light and heavy grazing. Under light grazing, APP increased in response to N + P additions in both the heath and meadow. Under heavy grazing, APP increased in response to N in the heath, with an additional positive effect of N + P combined, while APP increased in response to P and N + P additions in the meadow. These results clearly show that an increase in the grazing intensity of reindeer facilitated a shift towards more P-limited conditions in Scandinavian arctic tundra, by increasing N cycling without having a corresponding positive effect on P cycling. In the N-poor heath, reindeer increased soil N availability at least partly due to a shift towards more N-rich graminoids, while in the meadow, reindeer decreased soil P availability. The mechanisms behind this decrease remain unclear, but reindeer may simply export more P from the system than N due to their large P demand for the production of their antlers. Synthesis. We conclude that heavy and long-term reindeer grazing promoted a more P-limited tundra, thus experimentally confirming the potential of large mammalian herbivores to influence nutrient limitation of plant growth. A plain language summary is available for this article.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-27},\n\tjournal = {Functional Ecology},\n\tauthor = {Sitters, Judith and Cherif, Mehdi and Egelkraut, Dagmar and Giesler, Reiner and Olofsson, Johan},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.13342},\n\tkeywords = {\\#nosource, Fertilization experiment, fertilization experiment, herbivory, nitrogen, nutrient limitation, plant-herbivore interactions, plant–herbivore interactions, primary productivity, stoichiometry},\n\tpages = {1233--1242},\n}\n\n\n\n\n\n The potential of large mammalian herbivores to shift plant communities between nitrogen (N) and phosphorus (P) limitation has received little attention so far. However, herbivores can influence the cycling of these growth-limiting nutrients, and thereby affect plant nutrient limitation and productivity. Tundra ecosystems are nutrient-poor and commonly grazed by large herbivores like reindeer and may thus be responsive to such changes. Here, we examined the effect of long-term light and heavy reindeer grazing on nutrient limitation of plant growth in a Scandinavian arctic tundra. We are the first to conduct a factorial N and P fertilization experiment across the two grazing regimes in two functionally contrasting vegetation types: heath and meadow. Annual primary productivity (APP) showed contrasting responses to our fertilization treatments under light and heavy grazing. Under light grazing, APP increased in response to N + P additions in both the heath and meadow. Under heavy grazing, APP increased in response to N in the heath, with an additional positive effect of N + P combined, while APP increased in response to P and N + P additions in the meadow. These results clearly show that an increase in the grazing intensity of reindeer facilitated a shift towards more P-limited conditions in Scandinavian arctic tundra, by increasing N cycling without having a corresponding positive effect on P cycling. In the N-poor heath, reindeer increased soil N availability at least partly due to a shift towards more N-rich graminoids, while in the meadow, reindeer decreased soil P availability. The mechanisms behind this decrease remain unclear, but reindeer may simply export more P from the system than N due to their large P demand for the production of their antlers. Synthesis. We conclude that heavy and long-term reindeer grazing promoted a more P-limited tundra, thus experimentally confirming the potential of large mammalian herbivores to influence nutrient limitation of plant growth. A plain language summary is available for this article.\n
\n\n\n\n \n\n \n \n \n \n \n \n Local flooding history affects plant recruitment in riparian zones.\n \n \n \n \n\n\n \n Sarneel, J. M.; Bejarano, M. D.; van Oosterhout, M.; and Nilsson, C.\n\n\n \n\n\n\n Journal of Vegetation Science, 30(2): 224–234. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.12731\n\n\n\n
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\n\n\n@article{sarneel_local_2019,\n\ttitle = {Local flooding history affects plant recruitment in riparian zones},\n\tvolume = {30},\n\tcopyright = {© 2019 The Authors. Journal of Vegetation Science published by John Wiley \\& Sons Ltd on behalf of Internation Association of Vegetation Science.},\n\tissn = {1654-1103},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.12731},\n\tdoi = {10.1111/jvs.12731},\n\tabstract = {Aims Many rivers across the globe are severely impacted by changed flooding regimes, resulting in drastic shifts in vegetation, but the processes driving the exchange of flood-sensitive and flood-tolerant species are understood less. We studied the role of long-term and recent flooding histories for riparian plant recruitment in response to various changes in flooding regime. Location Vindel River catchment (Northern Sweden). Methods We experimentally changed long-term flooding regimes by transplanting turfs between high and low elevations in 2000 and in 2014 (n = 8 per treatment). We sowed seeds of five riparian species in both transplanted turfs and non-transplanted controls and counted seedling numbers over two growing seasons. Further, we inventoried natural seedling frequencies in 190 plots in 19 reaches in 2013 and 2014, and related natural seedling numbers to plot flooding history in the period 2012–2014. Results We observed effects of long-term flooding history in the second year of the transplantation study (2015), but not in the first year. In 2015, turfs transplanted to locations with less flooding resulted in higher plant recruitment while transplantation to sites with more frequent flooding reduced recruitment compared to the controls. Since these differences were only found in recently transplanted turfs and not in older turfs, the legacy effect of long-term flooding history can be transient. In the field seedling survey, similar differences were found between flooding-history categories in 2013, but not in 2014, when the moisture conditions of the most recent year determined flooding. Further, lowest seedling numbers were observed when the previous flooding occurred in winter, and higher seedling numbers when floods occurred in spring or not at all. Conclusions Both long-term and recent flooding histories can affect plant recruitment, and their influence should be taken into account when designing restoration projects.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Sarneel, Judith M. and Bejarano, Maria Dolores and van Oosterhout, Martin and Nilsson, Christer},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.12731},\n\tkeywords = {\\#nosource, dispersal filtering, environmental filtering, flood dynamics, historic contingency, legacy effects, plant recruitment window, regime shifts, window of opportunity, zonation},\n\tpages = {224--234},\n}\n\n\n\n\n\n Aims Many rivers across the globe are severely impacted by changed flooding regimes, resulting in drastic shifts in vegetation, but the processes driving the exchange of flood-sensitive and flood-tolerant species are understood less. We studied the role of long-term and recent flooding histories for riparian plant recruitment in response to various changes in flooding regime. Location Vindel River catchment (Northern Sweden). Methods We experimentally changed long-term flooding regimes by transplanting turfs between high and low elevations in 2000 and in 2014 (n = 8 per treatment). We sowed seeds of five riparian species in both transplanted turfs and non-transplanted controls and counted seedling numbers over two growing seasons. Further, we inventoried natural seedling frequencies in 190 plots in 19 reaches in 2013 and 2014, and related natural seedling numbers to plot flooding history in the period 2012–2014. Results We observed effects of long-term flooding history in the second year of the transplantation study (2015), but not in the first year. In 2015, turfs transplanted to locations with less flooding resulted in higher plant recruitment while transplantation to sites with more frequent flooding reduced recruitment compared to the controls. Since these differences were only found in recently transplanted turfs and not in older turfs, the legacy effect of long-term flooding history can be transient. In the field seedling survey, similar differences were found between flooding-history categories in 2013, but not in 2014, when the moisture conditions of the most recent year determined flooding. Further, lowest seedling numbers were observed when the previous flooding occurred in winter, and higher seedling numbers when floods occurred in spring or not at all. Conclusions Both long-term and recent flooding histories can affect plant recruitment, and their influence should be taken into account when designing restoration projects.\n
\n\n\n\n \n\n \n \n \n \n \n \n Interannual variation in seasonal diatom sedimentation reveals the importance of late winter processes and their timing for sediment signal formation.\n \n \n \n \n\n\n \n Maier, D. B.; Diehl, S.; and Bigler, C.\n\n\n \n\n\n\n Limnology and Oceanography, 64(3): 1186–1199. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11106\n\n\n\n
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\n\n\n@article{maier_interannual_2019,\n\ttitle = {Interannual variation in seasonal diatom sedimentation reveals the importance of late winter processes and their timing for sediment signal formation},\n\tvolume = {64},\n\tcopyright = {© 2019 Association for the Sciences of Limnology and Oceanography},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11106},\n\tdoi = {10.1002/lno.11106},\n\tabstract = {Disentangling the process information contained in a diatom sediment signature is crucial for reliable future predictions based on paleolimnological records. In this study, we combine limnological and paleolimnological monitoring to address the fundamental question: Which environmental information is contained in a diatom sediment signal? We compared annual diatom sequential sediment trap records with the diatom record of the annually varved lake sediment of Nylandssjön (northern Sweden) from three meteorologically different years (2012–2014). The seasonal patterns in diatom sedimentation were strikingly different in varve years 2012 and 2014 compared to varve year 2013. In 2012 and 2014, up to 70\\% of the annual flux occurred in a single spring month and was dominated by Cyclotella glomerata. In contrast, in 2013, peak fluxes were much lower and more annually integrated. Next, we compared the full-year diatom trap results with year round in-lake physical, chemical, and biological monitored parameters, as well as meteorological variables. Annual averages of environmental conditions did not explain the interannual variability in diatom sedimentation. Instead, the seasonality of diatom sedimentation was determined by the timing of the spring diatom bloom relative to lake over-turn in winters with warm vs. cold air temperature. With our combined limnological and paleolimnological monitoring approach, we find that an annual diatom signal can either contain primarily seasonal climate information from a short time period or be annually integrated. We synthesize our results in a novel conceptual model, which describes the response of sediment diatom signals to two distinct sequences of late-winter conditions.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Maier, Dominique Béatrice and Diehl, Sebastian and Bigler, Christian},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11106},\n\tkeywords = {\\#nosource},\n\tpages = {1186--1199},\n}\n\n\n\n\n\n Disentangling the process information contained in a diatom sediment signature is crucial for reliable future predictions based on paleolimnological records. In this study, we combine limnological and paleolimnological monitoring to address the fundamental question: Which environmental information is contained in a diatom sediment signal? We compared annual diatom sequential sediment trap records with the diatom record of the annually varved lake sediment of Nylandssjön (northern Sweden) from three meteorologically different years (2012–2014). The seasonal patterns in diatom sedimentation were strikingly different in varve years 2012 and 2014 compared to varve year 2013. In 2012 and 2014, up to 70% of the annual flux occurred in a single spring month and was dominated by Cyclotella glomerata. In contrast, in 2013, peak fluxes were much lower and more annually integrated. Next, we compared the full-year diatom trap results with year round in-lake physical, chemical, and biological monitored parameters, as well as meteorological variables. Annual averages of environmental conditions did not explain the interannual variability in diatom sedimentation. Instead, the seasonality of diatom sedimentation was determined by the timing of the spring diatom bloom relative to lake over-turn in winters with warm vs. cold air temperature. With our combined limnological and paleolimnological monitoring approach, we find that an annual diatom signal can either contain primarily seasonal climate information from a short time period or be annually integrated. We synthesize our results in a novel conceptual model, which describes the response of sediment diatom signals to two distinct sequences of late-winter conditions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Groundwater inflows control patterns and sources of greenhouse gas emissions from streams.\n \n \n \n \n\n\n \n Lupon, A.; Denfeld, B. A.; Laudon, H.; Leach, J.; Karlsson, J.; and Sponseller, R. A.\n\n\n \n\n\n\n Limnology and Oceanography, 64(4): 1545–1557. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11134\n\n\n\n
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\n\n\n@article{lupon_groundwater_2019,\n\ttitle = {Groundwater inflows control patterns and sources of greenhouse gas emissions from streams},\n\tvolume = {64},\n\tcopyright = {© 2019 Association for the Sciences of Limnology and Oceanography},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11134},\n\tdoi = {10.1002/lno.11134},\n\tabstract = {Headwater streams can be important sources of carbon dioxide (CO2) and methane (CH4) to the atmosphere. However, the influence of groundwater–stream connectivity on the patterns and sources of carbon (C) gas evasion is still poorly understood. We explored these connections in the boreal landscape through a detailed study of a 1.4 km lake outlet stream that is hydrologically fed by multiple topographically driven groundwater input zones. We measured stream and groundwater dissolved organic C (DOC), CO2, and CH4 concentrations every 50 m biweekly during the ice-free period and estimated in-stream C gas production through a mass balance model and independent estimates of aquatic metabolism. The spatial pattern of C gas concentrations was consistent over time, with peaks of both CH4 and CO2 concentrations occurring after each groundwater input zone. Moreover, lateral C gas inputs from riparian soils were the major source of CO2 and CH4 to the stream. DOC mineralization and CH4 oxidation within the stream accounted for 17–51\\% of stream CO2 emissions, and this contribution was the greatest during relatively higher flows. Overall, our results illustrate how the nature and arrangement of groundwater flowpaths can organize patterns of stream C concentrations, transformations, and emissions by acting as a direct source of gases and by supplying organic substrates that fuel aquatic metabolism. Hence, refined assessments of how catchment structure influences the timing and magnitude of groundwater–stream connections are crucial for mechanistically understanding and scaling C evasion rates from headwaters.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Lupon, Anna and Denfeld, Blaize A. and Laudon, Hjalmar and Leach, Jason and Karlsson, Jan and Sponseller, Ryan A.},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.11134},\n\tkeywords = {\\#nosource},\n\tpages = {1545--1557},\n}\n\n\n\n\n\n Headwater streams can be important sources of carbon dioxide (CO2) and methane (CH4) to the atmosphere. However, the influence of groundwater–stream connectivity on the patterns and sources of carbon (C) gas evasion is still poorly understood. We explored these connections in the boreal landscape through a detailed study of a 1.4 km lake outlet stream that is hydrologically fed by multiple topographically driven groundwater input zones. We measured stream and groundwater dissolved organic C (DOC), CO2, and CH4 concentrations every 50 m biweekly during the ice-free period and estimated in-stream C gas production through a mass balance model and independent estimates of aquatic metabolism. The spatial pattern of C gas concentrations was consistent over time, with peaks of both CH4 and CO2 concentrations occurring after each groundwater input zone. Moreover, lateral C gas inputs from riparian soils were the major source of CO2 and CH4 to the stream. DOC mineralization and CH4 oxidation within the stream accounted for 17–51% of stream CO2 emissions, and this contribution was the greatest during relatively higher flows. Overall, our results illustrate how the nature and arrangement of groundwater flowpaths can organize patterns of stream C concentrations, transformations, and emissions by acting as a direct source of gases and by supplying organic substrates that fuel aquatic metabolism. Hence, refined assessments of how catchment structure influences the timing and magnitude of groundwater–stream connections are crucial for mechanistically understanding and scaling C evasion rates from headwaters.\n
\n\n\n\n \n\n \n \n \n \n \n \n Evaluations of Climate and Land Management Effects on Lake Carbon Cycling Need to Account for Temporal Variability in CO2 Concentrations.\n \n \n \n \n\n\n \n Klaus, M.; Seekell, D. A.; Lidberg, W.; and Karlsson, J.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 33(3): 243–265. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005979\n\n\n\n
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\n\n\n@article{klaus_evaluations_2019,\n\ttitle = {Evaluations of {Climate} and {Land} {Management} {Effects} on {Lake} {Carbon} {Cycling} {Need} to {Account} for {Temporal} {Variability} in {CO2} {Concentrations}},\n\tvolume = {33},\n\tcopyright = {©2019. American Geophysical Union. All Rights Reserved.},\n\tissn = {1944-9224},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GB005979},\n\tdoi = {10.1029/2018GB005979},\n\tabstract = {Carbon dioxide (CO2) concentrations in lakes vary strongly over time. This variability is rarely captured by environmental monitoring but is crucial for accurately assessing the magnitude of lake CO2 emissions. However, it is unknown to what extent temporal variability needs to be captured to understand important drivers of lake carbon cycling such as climate and land management. We used environmental monitoring data of Swedish forest lakes collected in autumn (n = 439) and throughout the whole open water season (n = 22) from a wet and a dry year to assess temporal variability in effects of climate and forestry on CO2 concentrations across lakes. Effects differed depending on the season and year sampled. According to cross-lake comparisons based on autumn data, CO2 concentrations increased with annual mean air temperature (dry year) or catchment forest productivity (wet year) but were not related to colored dissolved organic matter concentrations. In contrast, open water-season averaged CO2 concentrations were similar across temperature and productivity gradients but increased with colored dissolved organic matter. These contradictions resulted from scale mismatches in input data, lead to weak explanatory power (R2 = 9–32\\%), and were consistent across published data from 79 temperate, boreal, and arctic lakes. In a global survey of 144 published studies, we identified a trade-off between temporal and spatial coverage of CO2 sampling. This trade-off clearly determines which conclusions are drawn from landscape-scale CO2 assessments. Accurate evaluations of the effects of climate and land management require spatially and temporally representative data that can be provided by emerging sensor technologies and forms of collaborative sampling.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Klaus, Marcus and Seekell, David A. and Lidberg, William and Karlsson, Jan},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005979},\n\tkeywords = {\\#nosource, carbon cycling, greenhouse gas, lake, sampling, seasonality, structural equation modeling},\n\tpages = {243--265},\n}\n\n\n\n\n\n Carbon dioxide (CO2) concentrations in lakes vary strongly over time. This variability is rarely captured by environmental monitoring but is crucial for accurately assessing the magnitude of lake CO2 emissions. However, it is unknown to what extent temporal variability needs to be captured to understand important drivers of lake carbon cycling such as climate and land management. We used environmental monitoring data of Swedish forest lakes collected in autumn (n = 439) and throughout the whole open water season (n = 22) from a wet and a dry year to assess temporal variability in effects of climate and forestry on CO2 concentrations across lakes. Effects differed depending on the season and year sampled. According to cross-lake comparisons based on autumn data, CO2 concentrations increased with annual mean air temperature (dry year) or catchment forest productivity (wet year) but were not related to colored dissolved organic matter concentrations. In contrast, open water-season averaged CO2 concentrations were similar across temperature and productivity gradients but increased with colored dissolved organic matter. These contradictions resulted from scale mismatches in input data, lead to weak explanatory power (R2 = 9–32%), and were consistent across published data from 79 temperate, boreal, and arctic lakes. In a global survey of 144 published studies, we identified a trade-off between temporal and spatial coverage of CO2 sampling. This trade-off clearly determines which conclusions are drawn from landscape-scale CO2 assessments. Accurate evaluations of the effects of climate and land management require spatially and temporally representative data that can be provided by emerging sensor technologies and forms of collaborative sampling.\n
\n\n\n\n \n\n \n \n \n \n \n \n Listening to air–water gas exchange in running waters.\n \n \n \n \n\n\n \n Klaus, M.; Geibrink, E.; Hotchkiss, E. R.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography: Methods, 17(7): 395–414. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lom3.10321\n\n\n\n
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\n\n\n@article{klaus_listening_2019,\n\ttitle = {Listening to air–water gas exchange in running waters},\n\tvolume = {17},\n\tcopyright = {© 2019 Association for the Sciences of Limnology and Oceanography},\n\tissn = {1541-5856},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lom3.10321},\n\tdoi = {10.1002/lom3.10321},\n\tabstract = {Air–water gas exchange velocities (k) are critical components of many biogeochemical and ecological process studies in aquatic systems. However, their high spatiotemporal variability is difficult to capture with traditional methods, especially in turbulent flow. Here, we investigate the potential of sound spectral analysis to infer k in running waters, based on the rationale that both turbulence and entrained bubbles drive gas exchange and cause a characteristic sound. We explored the relationship between k and sound spectral properties using laboratory experiments and field observations under a wide range of turbulence and bubble conditions. We estimated k using flux chamber measurements of CO2 exchange and recorded sound above and below the water surface by microphones and hydrophones, respectively. We found a strong influence of turbulence and bubbles on sound pressure levels (SPLs) at octave bands of 31.5 Hz and 1000 Hz, respectively. The difference in SPLs at these bands and background noise bands showed a linear correlation with k both in the laboratory (R2 = 0.93–0.99) and in the field (median R2 = 0.42–0.90). Underwater sound indices outperformed aerial sound indices in general, and indices based on hydraulic parameters in particular, in turbulent and bubbly surface flow. The results highlight the unique potential of acoustic techniques to predict k, isolate mechanisms, and improve the spatiotemporal coverage of k estimates in bubbly flow.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-26},\n\tjournal = {Limnology and Oceanography: Methods},\n\tauthor = {Klaus, Marcus and Geibrink, Erik and Hotchkiss, Erin R. and Karlsson, Jan},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lom3.10321},\n\tkeywords = {\\#nosource},\n\tpages = {395--414},\n}\n\n\n\n\n\n Air–water gas exchange velocities (k) are critical components of many biogeochemical and ecological process studies in aquatic systems. However, their high spatiotemporal variability is difficult to capture with traditional methods, especially in turbulent flow. Here, we investigate the potential of sound spectral analysis to infer k in running waters, based on the rationale that both turbulence and entrained bubbles drive gas exchange and cause a characteristic sound. We explored the relationship between k and sound spectral properties using laboratory experiments and field observations under a wide range of turbulence and bubble conditions. We estimated k using flux chamber measurements of CO2 exchange and recorded sound above and below the water surface by microphones and hydrophones, respectively. We found a strong influence of turbulence and bubbles on sound pressure levels (SPLs) at octave bands of 31.5 Hz and 1000 Hz, respectively. The difference in SPLs at these bands and background noise bands showed a linear correlation with k both in the laboratory (R2 = 0.93–0.99) and in the field (median R2 = 0.42–0.90). Underwater sound indices outperformed aerial sound indices in general, and indices based on hydraulic parameters in particular, in turbulent and bubbly surface flow. The results highlight the unique potential of acoustic techniques to predict k, isolate mechanisms, and improve the spatiotemporal coverage of k estimates in bubbly flow.\n
\n\n\n\n \n\n \n \n \n \n \n \n Food Inequality, Injustice, and Rights.\n \n \n \n \n\n\n \n D’Odorico, P.; Carr, J. A; Davis, K. F; Dell’Angelo, J.; and Seekell, D. A\n\n\n \n\n\n\n BioScience, 69(3): 180–190. March 2019.\n \n\n\n\n
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\n\n\n@article{dodorico_food_2019,\n\ttitle = {Food {Inequality}, {Injustice}, and {Rights}},\n\tvolume = {69},\n\tissn = {0006-3568},\n\turl = {https://doi.org/10.1093/biosci/biz002},\n\tdoi = {10.1093/biosci/biz002},\n\tabstract = {As humanity continues to grow in size, questions related to human rights and the existing unequal distribution of food resources have taken on greater urgency. Is inequality in food access unjust or a regrettable consequence of the geographic distribution of biophysical resources? To what extent are there obligations to redress inequalities in access to food? We draw from a human rights perspective to identify obligations associated with access to food and develop a quantitative framework to evaluate the fulfillment of the human right to food. We discuss the capacity of socioeconomic development to reduce inequalities in per capita food availability with respect to the distribution of biophysical resources among countries. Although, at the country level, international trade shows the capacity to reduce human rights deficits by increasing food availability in countries with limited food production, whether it actually improves the fulfillment of the right to food will depend on within-country inequality.},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {BioScience},\n\tauthor = {D’Odorico, Paolo and Carr, Joel A and Davis, Kyle F and Dell’Angelo, Jampel and Seekell, David A},\n\tmonth = mar,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {180--190},\n}\n\n\n\n\n\n As humanity continues to grow in size, questions related to human rights and the existing unequal distribution of food resources have taken on greater urgency. Is inequality in food access unjust or a regrettable consequence of the geographic distribution of biophysical resources? To what extent are there obligations to redress inequalities in access to food? We draw from a human rights perspective to identify obligations associated with access to food and develop a quantitative framework to evaluate the fulfillment of the human right to food. We discuss the capacity of socioeconomic development to reduce inequalities in per capita food availability with respect to the distribution of biophysical resources among countries. Although, at the country level, international trade shows the capacity to reduce human rights deficits by increasing food availability in countries with limited food production, whether it actually improves the fulfillment of the right to food will depend on within-country inequality.\n
\n\n\n\n \n\n \n \n \n \n \n \n How does environmental inter-annual variability shape aquatic microbial communities? A 40-year annual record of sedimentary DNA from a boreal lake (Nylandssjön, Sweden).\n \n \n \n \n\n\n \n Capo, E.; Rydberg, J.; Tolu, J.; Domaizon, I.; Debroas, D.; Bindler, R.; and Bigler, C.\n\n\n \n\n\n\n Frontiers in Ecology and Evolution, 7: 00245. 2019.\n \n\n\n\n
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\n\n\n@article{capo_how_2019,\n\ttitle = {How does environmental inter-annual variability shape aquatic microbial communities? {A} 40-year annual record of sedimentary {DNA} from a boreal lake ({Nylandssj}\\&\\#246;n, {Sweden})},\n\tvolume = {7},\n\tissn = {2296-701X},\n\tshorttitle = {How does environmental inter-annual variability shape aquatic microbial communities?},\n\turl = {https://www.frontiersin.org/articles/10.3389/fevo.2019.00245/abstract},\n\tdoi = {10.3389/fevo.2019.00245},\n\tabstract = {To assess the sensitivity of lakes to anthropogenically-driven environmental changes (e.g., nutrient supply, climate change), it is necessary to first isolate the effects of between-year variability in weather conditions. This variability can strongly impact a lake’s biological community especially in boreal and arctic areas where snow phenology play an important role in controlling the input of terrestrial matter to the lake. Identifying the importance of this inherent variability is difficult without time series that span at least several decades. Here, we applied a molecular approach (metabarcoding on eukaryotic 18S rRNA genes and qPCR on cyanobacterial 16S rRNA genes) to sedimentary DNA (sed-DNA) to unravel the annual variability of microbial community in 40 years’ sediment record from the boreal lake Nylandssjön which preserve annually-laminated sediments. Our comparison between seasonal meteorological data, sediment inorganic geochemistry (X-ray fluorescence analyses) and organic biomarkers (pyrolysis-gas chromatography/mass spectrometry analyses), demonstrated that inter-annual variability strongly influence the sediment composition in Nylandssjön. Spring temperature, snow and ice phenology (e.g. the percentage of snow loss in spring, the timing of lake ice-off) were identified as important drivers for the inputs of terrestrial material to the lake, and were therefore also important for shaping the aquatic biological community. Main changes were detected in the late-80s/mid-90s and mid-2000s associated with increases in algal productivity (see from organic biomarkers), in total richness of the protistan community and in relative abundances of Chlorophyta, Dinophyceae as well as Cyanobacteria abundance. These changes could be linked to a decline in terrestrial inputs to the lake during the snow melt and run-off period, which in turn was driven by warmer winter temperatures. Even if our data shows that meteorological factors do affect the sediment composition, they only explain part of the variability. This is most likely a consequence of the high inter-annual variability in abiotic and biotic parameters highlighting the difficulty to draw firm conclusions concerning drivers of biological changes at an annual or sub-annual resolution even with the 40-year varved sediment record from Nylandssjön. Hence, it is necessary to have an even longer time perspective in order to reveal the full implications of climate change.},\n\tlanguage = {English},\n\turldate = {2019-06-24},\n\tjournal = {Frontiers in Ecology and Evolution},\n\tauthor = {Capo, Eric and Rydberg, Johan and Tolu, Julie and Domaizon, Isabelle and Debroas, Didier and Bindler, Richard and Bigler, Christian},\n\tyear = {2019},\n\tkeywords = {\\#nosource, Inorganic geochemistry, Meteorological data, Varved sediment record, metabarcoding, organic proxies, paleolimnology, sedimentary DNA},\n\tpages = {00245},\n}\n\n\n\n\n\n To assess the sensitivity of lakes to anthropogenically-driven environmental changes (e.g., nutrient supply, climate change), it is necessary to first isolate the effects of between-year variability in weather conditions. This variability can strongly impact a lake’s biological community especially in boreal and arctic areas where snow phenology play an important role in controlling the input of terrestrial matter to the lake. Identifying the importance of this inherent variability is difficult without time series that span at least several decades. Here, we applied a molecular approach (metabarcoding on eukaryotic 18S rRNA genes and qPCR on cyanobacterial 16S rRNA genes) to sedimentary DNA (sed-DNA) to unravel the annual variability of microbial community in 40 years’ sediment record from the boreal lake Nylandssjön which preserve annually-laminated sediments. Our comparison between seasonal meteorological data, sediment inorganic geochemistry (X-ray fluorescence analyses) and organic biomarkers (pyrolysis-gas chromatography/mass spectrometry analyses), demonstrated that inter-annual variability strongly influence the sediment composition in Nylandssjön. Spring temperature, snow and ice phenology (e.g. the percentage of snow loss in spring, the timing of lake ice-off) were identified as important drivers for the inputs of terrestrial material to the lake, and were therefore also important for shaping the aquatic biological community. Main changes were detected in the late-80s/mid-90s and mid-2000s associated with increases in algal productivity (see from organic biomarkers), in total richness of the protistan community and in relative abundances of Chlorophyta, Dinophyceae as well as Cyanobacteria abundance. These changes could be linked to a decline in terrestrial inputs to the lake during the snow melt and run-off period, which in turn was driven by warmer winter temperatures. Even if our data shows that meteorological factors do affect the sediment composition, they only explain part of the variability. This is most likely a consequence of the high inter-annual variability in abiotic and biotic parameters highlighting the difficulty to draw firm conclusions concerning drivers of biological changes at an annual or sub-annual resolution even with the 40-year varved sediment record from Nylandssjön. Hence, it is necessary to have an even longer time perspective in order to reveal the full implications of climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Light and nutrient control phytoplankton biomass responses to global change in northern lakes.\n \n \n \n \n\n\n \n Bergström, A.; and Karlsson, J.\n\n\n \n\n\n\n Global Change Biology, 25(6): 2021–2029. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14623\n\n\n\n
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\n\n\n@article{bergstrom_light_2019,\n\ttitle = {Light and nutrient control phytoplankton biomass responses to global change in northern lakes},\n\tvolume = {25},\n\tcopyright = {© 2019 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14623},\n\tdoi = {10.1111/gcb.14623},\n\tabstract = {Global change affects terrestrial loadings of colored dissolved organic carbon (DOC) and nutrients to northern lakes. Still, little is known about how phytoplankton respond to changes in light and nutrient availability across gradients in lake DOC. In this study, we used results from whole-lake studies in northern Sweden to show that annual mean phytoplankton biomass expressed unimodal curved relationships across lake DOC gradients, peaking at threshold DOC levels of around 11 mg/L. Whole-lake single nutrient enrichment in selected lakes caused elevated biomass, with most pronounced effect at the threshold DOC level. These patterns give support to the suggested dual control by DOC on phytoplankton via nutrient (positively) and light (negatively) availability and imply that the lakes' location along the DOC axis is critical in determining to what extent phytoplankton respond to changes in DOC and/or nutrient loadings. By using data from the large Swedish Lake Monitoring Survey, we further estimated that 80\\% of northern Swedish lakes are below the DOC threshold, potentially experiencing increased phytoplankton biomass with browning alone, and/or combined with nutrient enrichment. The results support the previous model results on effects of browning and eutrophication on lake phytoplankton, and provide important understanding of how northern lakes may respond to future global changes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Bergström, Ann-Kristin and Karlsson, Jan},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14623},\n\tkeywords = {\\#nosource, Dissolved organic carbon, Nitrogen, Phosphorus, Phytoplankton, Whole-lake nutrient enrichment experiments, dissolved organic carbon, nitrogen, phosphorus, phytoplankton, whole-lake nutrient enrichment experiments},\n\tpages = {2021--2029},\n}\n\n\n\n\n\n Global change affects terrestrial loadings of colored dissolved organic carbon (DOC) and nutrients to northern lakes. Still, little is known about how phytoplankton respond to changes in light and nutrient availability across gradients in lake DOC. In this study, we used results from whole-lake studies in northern Sweden to show that annual mean phytoplankton biomass expressed unimodal curved relationships across lake DOC gradients, peaking at threshold DOC levels of around 11 mg/L. Whole-lake single nutrient enrichment in selected lakes caused elevated biomass, with most pronounced effect at the threshold DOC level. These patterns give support to the suggested dual control by DOC on phytoplankton via nutrient (positively) and light (negatively) availability and imply that the lakes' location along the DOC axis is critical in determining to what extent phytoplankton respond to changes in DOC and/or nutrient loadings. By using data from the large Swedish Lake Monitoring Survey, we further estimated that 80% of northern Swedish lakes are below the DOC threshold, potentially experiencing increased phytoplankton biomass with browning alone, and/or combined with nutrient enrichment. The results support the previous model results on effects of browning and eutrophication on lake phytoplankton, and provide important understanding of how northern lakes may respond to future global changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Defoliation of a grass is mediated by the positive effect of dung deposition, moss removal and enhanced soil nutrient contents: results from a reindeer grazing simulation experiment.\n \n \n \n \n\n\n \n Barthelemy, H.; Dorrepaal, E.; and Olofsson, J.\n\n\n \n\n\n\n Oikos, 128(10): 1515–1524. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/oik.06310\n\n\n\n
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\n\n\n@article{barthelemy_defoliation_2019,\n\ttitle = {Defoliation of a grass is mediated by the positive effect of dung deposition, moss removal and enhanced soil nutrient contents: results from a reindeer grazing simulation experiment},\n\tvolume = {128},\n\tcopyright = {© 2019 The Authors. Oikos © 2019 Nordic Society Oikos},\n\tissn = {1600-0706},\n\tshorttitle = {Defoliation of a grass is mediated by the positive effect of dung deposition, moss removal and enhanced soil nutrient contents},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.06310},\n\tdoi = {10.1111/oik.06310},\n\tabstract = {Herbivory is one of the key drivers shaping plant community dynamics. Herbivores can strongly influence plant productivity directly through defoliation and the return of nutrients in the form of dung and urine, but also indirectly by reducing the abundance of neighbouring plants and inducing changes in soil processes. However, the relative importance of these processes is poorly understood. We, therefore, established a common garden experiment to study plant responses to defoliation, dung addition, moss cover, and the soil legacy of reindeer grazing. We used an arctic tundra grazed by reindeer as our study system, and Festuca ovina, a common grazing-tolerant grass species as the model species. The soil legacy of reindeer grazing had the strongest effect on plants, and resulted in higher growth in soils originating from previously heavily-grazed sites. Defoliation also had a strong effect and reduced shoot and root growth and nutrient uptake. Plants did not fully compensate for the tissue lost due to defoliation, even when nutrient availability was high. In contrast, defoliation enhanced plant nitrogen concentrations. Dung addition increased plant production, nitrogen concentrations and nutrient uptake, although the effect was fairly small. Mosses also had a positive effect on aboveground plant production as long as the plants were not defoliated. The presence of a thick moss layer reduced plant growth following defoliation. This study demonstrates that grasses, even though they suffer from defoliation, can tolerate high densities of herbivores when all aspects of herbivores on ecosystems are taken into account. Our results further show that the positive effect of herbivores on plant growth via changes in soil properties is essential for plants to cope with a high grazing pressure. The strong effect of the soil legacy of reindeer grazing reveals that herbivores can have long-lasting effects on plant productivity and ecosystem functioning after grazing has ceased.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2024-03-26},\n\tjournal = {Oikos},\n\tauthor = {Barthelemy, Hélène and Dorrepaal, Ellen and Olofsson, Johan},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/oik.06310},\n\tkeywords = {\\#nosource, Arctic tundra, Festuca ovina, plant compensatory growth, plant nitrogen content, reindeer grazing, soil legacy},\n\tpages = {1515--1524},\n}\n\n\n\n\n\n Herbivory is one of the key drivers shaping plant community dynamics. Herbivores can strongly influence plant productivity directly through defoliation and the return of nutrients in the form of dung and urine, but also indirectly by reducing the abundance of neighbouring plants and inducing changes in soil processes. However, the relative importance of these processes is poorly understood. We, therefore, established a common garden experiment to study plant responses to defoliation, dung addition, moss cover, and the soil legacy of reindeer grazing. We used an arctic tundra grazed by reindeer as our study system, and Festuca ovina, a common grazing-tolerant grass species as the model species. The soil legacy of reindeer grazing had the strongest effect on plants, and resulted in higher growth in soils originating from previously heavily-grazed sites. Defoliation also had a strong effect and reduced shoot and root growth and nutrient uptake. Plants did not fully compensate for the tissue lost due to defoliation, even when nutrient availability was high. In contrast, defoliation enhanced plant nitrogen concentrations. Dung addition increased plant production, nitrogen concentrations and nutrient uptake, although the effect was fairly small. Mosses also had a positive effect on aboveground plant production as long as the plants were not defoliated. The presence of a thick moss layer reduced plant growth following defoliation. This study demonstrates that grasses, even though they suffer from defoliation, can tolerate high densities of herbivores when all aspects of herbivores on ecosystems are taken into account. Our results further show that the positive effect of herbivores on plant growth via changes in soil properties is essential for plants to cope with a high grazing pressure. The strong effect of the soil legacy of reindeer grazing reveals that herbivores can have long-lasting effects on plant productivity and ecosystem functioning after grazing has ceased.\n
\n\n\n\n \n\n \n \n \n \n \n \n Patterns and drivers in spring and autumn phenology differ above- and belowground in four ecosystems under the same macroclimatic conditions.\n \n \n \n \n\n\n \n Schwieger, S.; Blume-Werry, G.; Peters, B.; Smiljanic, M.; and Kreyling, J.\n\n\n \n\n\n\n Plant and Soil, 445(1-2): 217–229. 2019.\n Publisher: Springer\n\n\n\n
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\n\n\n@article{schwieger_patterns_2019,\n\ttitle = {Patterns and drivers in spring and autumn phenology differ above- and belowground in four ecosystems under the same macroclimatic conditions},\n\tvolume = {445},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-187824},\n\tdoi = {10.1007/s11104-019-04300-w},\n\tabstract = {Background and aims: Start and end of the growing season determine important ecosystem processes, but their drivers may differ above-and belowground, between autumn and spring, and between ecosyste ...},\n\tlanguage = {eng},\n\tnumber = {1-2},\n\turldate = {2024-03-26},\n\tjournal = {Plant and Soil},\n\tauthor = {Schwieger, Sarah and Blume-Werry, Gesche and Peters, Bo and Smiljanic, Marko and Kreyling, Juergen},\n\tyear = {2019},\n\tnote = {Publisher: Springer},\n\tpages = {217--229},\n}\n\n\n\n\n\n Background and aims: Start and end of the growing season determine important ecosystem processes, but their drivers may differ above-and belowground, between autumn and spring, and between ecosyste ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Biophysical controls on CO2 evasion from Arctic inland waters.\n \n \n \n \n\n\n \n Rocher-Ros, G.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2019.\n Publisher: Umeå University\n\n\n\n
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\n\n\n@phdthesis{rocher-ros_biophysical_2019,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Biophysical controls on {CO2} evasion from {Arctic} inland waters},\n\turl = {http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-158882},\n\tabstract = {DiVA portal is a finding tool for research publications and student theses written at the following 49 universities and research institutions.},\n\tlanguage = {eng},\n\turldate = {2020-03-19},\n\tschool = {Umeå University},\n\tauthor = {Rocher-Ros, Gerard},\n\tcollaborator = {Giesler, Reiner and Sponseller, Ryan A. and Bergström, Ann-Kristin},\n\tyear = {2019},\n\tnote = {Publisher: Umeå University},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n DiVA portal is a finding tool for research publications and student theses written at the following 49 universities and research institutions.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Legacy Effects of Winter Climate on Microbial Functioning After Snowmelt in a Subarctic Tundra.\n \n \n \n \n\n\n \n Väisänen, M.; Gavazov, K.; Krab, E. J.; and Dorrepaal, E.\n\n\n \n\n\n\n Microbial Ecology, 77(1): 186–190. January 2019.\n \n\n\n\n
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\n\n\n@article{vaisanen_legacy_2019,\n\ttitle = {The {Legacy} {Effects} of {Winter} {Climate} on {Microbial} {Functioning} {After} {Snowmelt} in a {Subarctic} {Tundra}},\n\tvolume = {77},\n\tissn = {1432-184X},\n\turl = {https://doi.org/10.1007/s00248-018-1213-1},\n\tdoi = {10.1007/s00248-018-1213-1},\n\tabstract = {Warming-induced increases in microbial CO2 release in northern tundra may positively feedback to climate change. However, shifts in microbial extracellular enzyme activities (EEAs) may alter the impacts of warming over the longer term. We investigated the in situ effects of 3 years of winter warming in combination with the in vitro effects of a rapid warming (6 days) on microbial CO2 release and EEAs in a subarctic tundra heath after snowmelt in spring. Winter warming did not change microbial CO2 release at ambient (10 °C) or at rapidly increased temperatures, i.e., a warm spell (18 °C) but induced changes (P {\\textless} 0.1) in the Q10 of microbial respiration and an oxidative EEA. Thus, although warmer winters may induce legacy effects in microbial temperature acclimation, we found no evidence for changes in potential carbon mineralization after spring thaw.},\n\tnumber = {1},\n\tjournal = {Microbial Ecology},\n\tauthor = {Väisänen, Maria and Gavazov, Konstantin and Krab, Eveline J. and Dorrepaal, Ellen},\n\tmonth = jan,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {186--190},\n}\n\n\n\n\n\n Warming-induced increases in microbial CO2 release in northern tundra may positively feedback to climate change. However, shifts in microbial extracellular enzyme activities (EEAs) may alter the impacts of warming over the longer term. We investigated the in situ effects of 3 years of winter warming in combination with the in vitro effects of a rapid warming (6 days) on microbial CO2 release and EEAs in a subarctic tundra heath after snowmelt in spring. Winter warming did not change microbial CO2 release at ambient (10 °C) or at rapidly increased temperatures, i.e., a warm spell (18 °C) but induced changes (P \\textless 0.1) in the Q10 of microbial respiration and an oxidative EEA. Thus, although warmer winters may induce legacy effects in microbial temperature acclimation, we found no evidence for changes in potential carbon mineralization after spring thaw.\n
\n\n\n\n \n\n \n \n \n \n \n Widespread drying of European peatlands in recent centuries.\n \n \n \n\n\n \n Swindles, G. T; Morris, P. J; Mullan, D. J; Payne, R. J; Roland, T. P; Amesbury, M. J; Lamentowicz, M.; Turner, T E.; Gallego-Sala, A.; Sim, T.; and others\n\n\n \n\n\n\n Nature Geoscience, 12(11): 922–928. 2019.\n Publisher: Nature Publishing Group UK London\n\n\n\n
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\n\n\n@article{swindles_widespread_2019,\n\ttitle = {Widespread drying of {European} peatlands in recent centuries},\n\tvolume = {12},\n\tdoi = {10.1038/s41561-019-0462-z},\n\tabstract = {Climate warming and human impacts are thought to be causing peatlands to dry, potentially converting them from sinks to sources of carbon. However, it is unclear whether the hydrological status of peatlands has moved beyond their natural envelope. Here we show that European peatlands have undergone substantial, widespread drying during the last {\\textasciitilde}300 years. We analyse testate amoeba-derived hydrological reconstructions from 31 peatlands across Britain, Ireland, Scandinavia and Continental Europe to examine changes in peatland surface wetness during the last 2,000 years. We find that 60\\% of our study sites were drier during the period 1800–2000 ce than they have been for the last 600 years, 40\\% of sites were drier than they have been for 1,000 years and 24\\% of sites were drier than they have been for 2,000 years. This marked recent transition in the hydrology of European peatlands is concurrent with compound pressures including climatic drying, warming and direct human impacts on peatlands, although these factors vary among regions and individual sites. Our results suggest that the wetness of many European peatlands may now be moving away from natural baselines. Our findings highlight the need for effective management and restoration of European peatlands.},\n\tnumber = {11},\n\tjournal = {Nature Geoscience},\n\tauthor = {Swindles, Graeme T and Morris, Paul J and Mullan, Donal J and Payne, Richard J and Roland, Thomas P and Amesbury, Matthew J and Lamentowicz, Mariusz and Turner, T Edward and Gallego-Sala, Angela and Sim, Thomas and {others}},\n\tyear = {2019},\n\tnote = {Publisher: Nature Publishing Group UK London},\n\tkeywords = {\\#nosource},\n\tpages = {922--928},\n}\n\n\n\n\n\n Climate warming and human impacts are thought to be causing peatlands to dry, potentially converting them from sinks to sources of carbon. However, it is unclear whether the hydrological status of peatlands has moved beyond their natural envelope. Here we show that European peatlands have undergone substantial, widespread drying during the last ~300 years. We analyse testate amoeba-derived hydrological reconstructions from 31 peatlands across Britain, Ireland, Scandinavia and Continental Europe to examine changes in peatland surface wetness during the last 2,000 years. We find that 60% of our study sites were drier during the period 1800–2000 ce than they have been for the last 600 years, 40% of sites were drier than they have been for 1,000 years and 24% of sites were drier than they have been for 2,000 years. This marked recent transition in the hydrology of European peatlands is concurrent with compound pressures including climatic drying, warming and direct human impacts on peatlands, although these factors vary among regions and individual sites. Our results suggest that the wetness of many European peatlands may now be moving away from natural baselines. Our findings highlight the need for effective management and restoration of European peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant expansion drives bacteria and collembola communities under winter climate change in frost-affected tundra.\n \n \n \n \n\n\n \n Krab, E. J.; Monteux, S.; Weedon, J. T.; and Dorrepaal, E.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 138: 107569. November 2019.\n \n\n\n\n
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\n\n\n@article{krab_plant_2019,\n\ttitle = {Plant expansion drives bacteria and collembola communities under winter climate change in frost-affected tundra},\n\tvolume = {138},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071719302330},\n\tdoi = {10.1016/j.soilbio.2019.107569},\n\tabstract = {At high latitudes, winter warming facilitates vegetation expansion into barren frost-affected soils. The interplay of changes in winter climate and plant presence may alter soil functioning via effects on decomposers. Responses of decomposer soil fauna and microorganisms to such changes likely differ from each other, since their life histories, dispersal mechanisms and microhabitats vary greatly. We investigated the relative impacts of short-term winter warming and increases in plant cover on bacteria and collembola community composition in cryoturbated, non-sorted circle tundra. By covering non-sorted circles with insulating gardening fibre cloth (fleeces) or using stone walls accumulating snow, we imposed two climate-change scenarios: snow accumulation increased autumn-to-late winter soil temperatures (−1 cm) by 1.4 °C, while fleeces warmed soils during that period by 1 °C and increased spring temperatures by 1.1 °C. Summer bacteria and collembola communities were sampled from within-circle locations differing in vegetation abundance and soil properties. Two years of winter warming had no effects on either decomposer community. Instead, their community compositions were strongly determined by sampling location: communities in barren circle centres were distinct from those in vegetated outer rims, while communities in sparsely vegetated patches of circle centres were intermediate. Diversity patterns indicate that collembola communities are tightly linked to plant presence while bacteria communities correlated with soil properties. Our results thus suggest that direct effects of short-term winter warming are likely to be minimal, but that vegetation encroachment on barren cryoturbated ground will affect decomposer community composition substantially. At decadal timescales, collembola community changes may follow relatively fast after warming-driven plant establishment into barren areas, whereas bacteria communities may take longer to respond. If shifts in decomposer community composition are indicative for changes in their activity, vegetation overgrowth will likely have much stronger effects on soil functioning in frost-affected tundra than short-term winter warming.},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Krab, Eveline J. and Monteux, Sylvain and Weedon, James T. and Dorrepaal, Ellen},\n\tmonth = nov,\n\tyear = {2019},\n\tkeywords = {\\#nosource, Arctic, Global warming, Microbes, Shrub encroachment, Snow, Soil fauna},\n\tpages = {107569},\n}\n\n\n\n\n\n At high latitudes, winter warming facilitates vegetation expansion into barren frost-affected soils. The interplay of changes in winter climate and plant presence may alter soil functioning via effects on decomposers. Responses of decomposer soil fauna and microorganisms to such changes likely differ from each other, since their life histories, dispersal mechanisms and microhabitats vary greatly. We investigated the relative impacts of short-term winter warming and increases in plant cover on bacteria and collembola community composition in cryoturbated, non-sorted circle tundra. By covering non-sorted circles with insulating gardening fibre cloth (fleeces) or using stone walls accumulating snow, we imposed two climate-change scenarios: snow accumulation increased autumn-to-late winter soil temperatures (−1 cm) by 1.4 °C, while fleeces warmed soils during that period by 1 °C and increased spring temperatures by 1.1 °C. Summer bacteria and collembola communities were sampled from within-circle locations differing in vegetation abundance and soil properties. Two years of winter warming had no effects on either decomposer community. Instead, their community compositions were strongly determined by sampling location: communities in barren circle centres were distinct from those in vegetated outer rims, while communities in sparsely vegetated patches of circle centres were intermediate. Diversity patterns indicate that collembola communities are tightly linked to plant presence while bacteria communities correlated with soil properties. Our results thus suggest that direct effects of short-term winter warming are likely to be minimal, but that vegetation encroachment on barren cryoturbated ground will affect decomposer community composition substantially. At decadal timescales, collembola community changes may follow relatively fast after warming-driven plant establishment into barren areas, whereas bacteria communities may take longer to respond. If shifts in decomposer community composition are indicative for changes in their activity, vegetation overgrowth will likely have much stronger effects on soil functioning in frost-affected tundra than short-term winter warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dwelling in the deep – strongly increased root growth and rooting depth enhance plant interactions with thawing permafrost soil.\n \n \n \n \n\n\n \n Blume-Werry, G.; Milbau, A.; Teuber, L. M.; Johansson, M.; and Dorrepaal, E.\n\n\n \n\n\n\n New Phytologist, 223(3): 1328–1339. August 2019.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{blume-werry_dwelling_2019,\n\ttitle = {Dwelling in the deep – strongly increased root growth and rooting depth enhance plant interactions with thawing permafrost soil},\n\tvolume = {223},\n\tissn = {0028-646X},\n\turl = {https://doi.org/10.1111/nph.15903},\n\tdoi = {10.1111/nph.15903},\n\tabstract = {Summary Climate-warming-induced permafrost thaw exposes large amounts of carbon and nitrogen in soil at considerable depths, below the seasonally thawing active layer. The extent to which plant roots can reach and interact with these hitherto detached, deep carbon and nitrogen stores remains unknown. We aimed to quantify how permafrost thaw affects root dynamics across soil depths and plant functional types compared with above-ground abundance, and potential consequences for plant?soil interactions. A decade of experimental permafrost thaw strongly increased total root length and growth in the active layer, and deep roots invaded the newly thawed permafrost underneath. Root litter input to soil across all depths was 10 times greater with permafrost thaw. Root growth timing was unaffected by experimental permafrost thaw but peaked later in deeper soil, reflecting the seasonally receding thaw front. Deep-rooting species could sequester 15N added at the base of the ambient active layer in October, which was after root growth had ceased. Deep soil organic matter that has long been locked up in permafrost is thus no longer detached from plant processes upon thaw. Whether via nutrient uptake, carbon storage, or rhizosphere priming, plant root interactions with thawing permafrost soils may feed back on our climate both positively and negatively.},\n\tnumber = {3},\n\turldate = {2023-07-21},\n\tjournal = {New Phytologist},\n\tauthor = {Blume-Werry, Gesche and Milbau, Ann and Teuber, Laurenz M. and Johansson, Margareta and Dorrepaal, Ellen},\n\tmonth = aug,\n\tyear = {2019},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, Eriophorum, arctic tundra, fine roots, minirhizotrons, peatland, root biomass, root litter, root phenology},\n\tpages = {1328--1339},\n}\n\n\n\n\n\n Summary Climate-warming-induced permafrost thaw exposes large amounts of carbon and nitrogen in soil at considerable depths, below the seasonally thawing active layer. The extent to which plant roots can reach and interact with these hitherto detached, deep carbon and nitrogen stores remains unknown. We aimed to quantify how permafrost thaw affects root dynamics across soil depths and plant functional types compared with above-ground abundance, and potential consequences for plant?soil interactions. A decade of experimental permafrost thaw strongly increased total root length and growth in the active layer, and deep roots invaded the newly thawed permafrost underneath. Root litter input to soil across all depths was 10 times greater with permafrost thaw. Root growth timing was unaffected by experimental permafrost thaw but peaked later in deeper soil, reflecting the seasonally receding thaw front. Deep-rooting species could sequester 15N added at the base of the ambient active layer in October, which was after root growth had ceased. Deep soil organic matter that has long been locked up in permafrost is thus no longer detached from plant processes upon thaw. Whether via nutrient uptake, carbon storage, or rhizosphere priming, plant root interactions with thawing permafrost soils may feed back on our climate both positively and negatively.\n
\n\n\n\n \n\n \n \n \n \n \n \n Coupled carbon and nitrogen losses in response to seven years of chronic warming in subarctic soils.\n \n \n \n \n\n\n \n Marañón-Jiménez, S.; Peñuelas, J.; Richter, A.; Sigurdsson, B. D.; Fuchslueger, L.; Leblans, N. I. W.; and Janssens, I. A.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 134: 152–161. July 2019.\n \n\n\n\n
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\n\n\n@article{maranon-jimenez_coupled_2019,\n\ttitle = {Coupled carbon and nitrogen losses in response to seven years of chronic warming in subarctic soils},\n\tvolume = {134},\n\tissn = {0038-0717},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0038071719301038},\n\tdoi = {10.1016/j.soilbio.2019.03.028},\n\tabstract = {Increasing temperatures may alter the stoichiometric demands of soil microbes and impair their capacity to stabilize carbon (C) and retain nitrogen (N), with critical consequences for the soil C and N storage at high latitude soils. Geothermally active areas in Iceland provided wide, continuous and stable gradients of soil temperatures to test this hypothesis. In order to characterize the stoichiometric demands of microbes from these subarctic soils, we incubated soils from ambient temperatures after the factorial addition of C, N and P substrates separately and in combination. In a second experiment, soils that had been exposed to different in situ warming intensities (+0, +0.5, +1.8, +3.4, +8.7, +15.9 °C above ambient) for seven years were incubated after the combined addition of C, N and P to evaluate the capacity of soil microbes to store and immobilize C and N at the different warming scenarios. The seven years of chronic soil warming triggered large and proportional soil C and N losses (4.1 ± 0.5\\% °C−1 of the stocks in unwarmed soils) from the upper 10 cm of soil, with a predominant depletion of the physically accessible organic substrates that were weakly sorbed in soil minerals up to 8.7 °C warming. Soil microbes met the increasing respiratory demands under conditions of low C accessibility at the expenses of a reduction of the standing biomass in warmer soils. This together with the strict microbial C:N stoichiometric demands also constrained their capacity of N retention, and increased the vulnerability of soil to N losses. Our findings suggest a strong control of microbial physiology and C:N stoichiometric needs on the retention of soil N and on the resilience of soil C stocks from high-latitudes to warming, particularly during periods of vegetation dormancy and low C inputs.},\n\turldate = {2019-05-20},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Marañón-Jiménez, S. and Peñuelas, J. and Richter, A. and Sigurdsson, B. D. and Fuchslueger, L. and Leblans, N. I. W. and Janssens, I. A.},\n\tmonth = jul,\n\tyear = {2019},\n\tkeywords = {\\#nosource, Microbial biomass, Microbial carbon and nutrients limitation, Nitrogen immobilization, Nitrogen loss, Substrate induced respiration, Temperature increase},\n\tpages = {152--161},\n}\n\n\n\n\n\n Increasing temperatures may alter the stoichiometric demands of soil microbes and impair their capacity to stabilize carbon (C) and retain nitrogen (N), with critical consequences for the soil C and N storage at high latitude soils. Geothermally active areas in Iceland provided wide, continuous and stable gradients of soil temperatures to test this hypothesis. In order to characterize the stoichiometric demands of microbes from these subarctic soils, we incubated soils from ambient temperatures after the factorial addition of C, N and P substrates separately and in combination. In a second experiment, soils that had been exposed to different in situ warming intensities (+0, +0.5, +1.8, +3.4, +8.7, +15.9 °C above ambient) for seven years were incubated after the combined addition of C, N and P to evaluate the capacity of soil microbes to store and immobilize C and N at the different warming scenarios. The seven years of chronic soil warming triggered large and proportional soil C and N losses (4.1 ± 0.5% °C−1 of the stocks in unwarmed soils) from the upper 10 cm of soil, with a predominant depletion of the physically accessible organic substrates that were weakly sorbed in soil minerals up to 8.7 °C warming. Soil microbes met the increasing respiratory demands under conditions of low C accessibility at the expenses of a reduction of the standing biomass in warmer soils. This together with the strict microbial C:N stoichiometric demands also constrained their capacity of N retention, and increased the vulnerability of soil to N losses. Our findings suggest a strong control of microbial physiology and C:N stoichiometric needs on the retention of soil N and on the resilience of soil C stocks from high-latitudes to warming, particularly during periods of vegetation dormancy and low C inputs.\n
\n\n\n\n \n\n \n \n \n \n \n \n High carbon emissions from thermokarst lakes of Western Siberia.\n \n \n \n \n\n\n \n Serikova, S.; Pokrovsky, O. S.; Laudon, H.; Krickov, I. V.; Lim, A. G.; Manasypov, R. M.; and Karlsson, J.\n\n\n \n\n\n\n Nature Communications, 10(1): 1552. April 2019.\n \n\n\n\n
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\n\n\n@article{serikova_high_2019,\n\ttitle = {High carbon emissions from thermokarst lakes of {Western} {Siberia}},\n\tvolume = {10},\n\tcopyright = {2019 The Author(s)},\n\tissn = {2041-1723},\n\turl = {http://www.nature.com/articles/s41467-019-09592-1},\n\tdoi = {10.1038/s41467-019-09592-1},\n\tabstract = {The Western Siberia Lowland (WSL) is the world’s largest frozen peatland complex, however carbon emissions (CO2+CH4) from lakes in this region remain unknown. Here, the authors sample 76 lakes and show high carbon emissions from lakes across all permafrost zones in the WSL.},\n\tlanguage = {En},\n\tnumber = {1},\n\turldate = {2019-06-24},\n\tjournal = {Nature Communications},\n\tauthor = {Serikova, S. and Pokrovsky, O. S. and Laudon, H. and Krickov, I. V. and Lim, A. G. and Manasypov, R. M. and Karlsson, J.},\n\tmonth = apr,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {1552},\n}\n\n\n\n\n\n The Western Siberia Lowland (WSL) is the world’s largest frozen peatland complex, however carbon emissions (CO2+CH4) from lakes in this region remain unknown. Here, the authors sample 76 lakes and show high carbon emissions from lakes across all permafrost zones in the WSL.\n
\n\n\n\n \n\n \n \n \n \n \n \n Acclimation of Fine Root Systems to Soil Warming: Comparison of an Experimental Setup and a Natural Soil Temperature Gradient.\n \n \n \n \n\n\n \n Parts, K.; Tedersoo, L.; Schindlbacher, A.; Sigurdsson, B. D.; Leblans, N. I. W.; Oddsdóttir, E. S.; Borken, W.; and Ostonen, I.\n\n\n \n\n\n\n Ecosystems, 22(3): 457–472. July 2019.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{parts_acclimation_2019,\n\ttitle = {Acclimation of {Fine} {Root} {Systems} to {Soil} {Warming}: {Comparison} of an {Experimental} {Setup} and a {Natural} {Soil} {Temperature} {Gradient}},\n\tvolume = {22},\n\tissn = {1435-0629},\n\tshorttitle = {Acclimation of {Fine} {Root} {Systems} to {Soil} {Warming}},\n\turl = {https://doi.org/10.1007/s10021-018-0280-y},\n\tdoi = {10.1007/s10021-018-0280-y},\n\tabstract = {Global warming is predicted to impact high-latitude and high-altitude forests severely, jeopardizing their overall functioning and carbon storage, both of which depend on the warming response of tree fine root systems. This paper investigates the effect of soil warming on the biomass, morphology and colonizing ectomycorrhizal community of spruce fine and absorptive fine roots. We compare the responses of spruce roots growing at a man-made long-term soil warming (+ 4°C) experiment to results obtained from a geothermal soil temperature gradient (+ 1 to + 14°C) extending to the forest die-off edge, to shed light on the generalizability of the warming response and reveal any thresholds in acclimation ability. Trees in warmer soils formed longer and less-branched absorptive roots with higher specific root length and area, and lower root tissue density in both spruce stands, irrespective of warming method and location. Soil warming at the experimental warming site also supported the occurrence of a more varied EcM community and an increase in the abundance of Tomentella spp., indicating a shift in nutrient foraging. Fine and absorptive fine root biomass decreased toward warmer soil, with a sharp reduction occurring between + 4 and + 6°C from the ambient and leading to the collapse of the fine root system at the geothermal gradient. At the experimental warming site, the applied + 4°C warming had no effect on fine and absorptive fine root biomass. The similar fine root responses at the two warming sites suggest that the observations possibly reflect general acclimation patterns in spruce forests to global warming.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2019-05-20},\n\tjournal = {Ecosystems},\n\tauthor = {Parts, Kaarin and Tedersoo, Leho and Schindlbacher, Andreas and Sigurdsson, Bjarni D. and Leblans, Niki I. W. and Oddsdóttir, Edda S. and Borken, Werner and Ostonen, Ivika},\n\tmonth = jul,\n\tyear = {2019},\n\tkeywords = {\\#nosource, Picea abies, Picea sitchensis, boreal and temperate forests, climate change, ectomycorrhiza, fine root biomass, root tissue density, root traits, soil temperature gradient, specific root length},\n\tpages = {457--472},\n}\n\n\n\n\n\n Global warming is predicted to impact high-latitude and high-altitude forests severely, jeopardizing their overall functioning and carbon storage, both of which depend on the warming response of tree fine root systems. This paper investigates the effect of soil warming on the biomass, morphology and colonizing ectomycorrhizal community of spruce fine and absorptive fine roots. We compare the responses of spruce roots growing at a man-made long-term soil warming (+ 4°C) experiment to results obtained from a geothermal soil temperature gradient (+ 1 to + 14°C) extending to the forest die-off edge, to shed light on the generalizability of the warming response and reveal any thresholds in acclimation ability. Trees in warmer soils formed longer and less-branched absorptive roots with higher specific root length and area, and lower root tissue density in both spruce stands, irrespective of warming method and location. Soil warming at the experimental warming site also supported the occurrence of a more varied EcM community and an increase in the abundance of Tomentella spp., indicating a shift in nutrient foraging. Fine and absorptive fine root biomass decreased toward warmer soil, with a sharp reduction occurring between + 4 and + 6°C from the ambient and leading to the collapse of the fine root system at the geothermal gradient. At the experimental warming site, the applied + 4°C warming had no effect on fine and absorptive fine root biomass. The similar fine root responses at the two warming sites suggest that the observations possibly reflect general acclimation patterns in spruce forests to global warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Uneven global distribution of food web studies under climate change.\n \n \n \n \n\n\n \n Cameron, E. K.; Sundqvist, M. K.; Keith, S. A.; CaraDonna, P. J.; Mousing, E. A.; Nilsson, K. A.; Metcalfe, D. B.; and Classen, A. T.\n\n\n \n\n\n\n Ecosphere, 10(3): e02645. March 2019.\n \n\n\n\n
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\n\n\n@article{cameron_uneven_2019,\n\ttitle = {Uneven global distribution of food web studies under climate change},\n\tvolume = {10},\n\tissn = {2150-8925},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2645},\n\tdoi = {10.1002/ecs2.2645},\n\tabstract = {Abstract Trophic interactions within food webs affect species distributions, coexistence, and provision of ecosystem services but can be strongly impacted by climatic changes. Understanding these impacts is therefore essential for managing ecosystems and sustaining human well-being. Here, we conducted a global synthesis of terrestrial, marine, and freshwater studies to identify key gaps in our knowledge of climate change impacts on food webs and determine whether the areas currently studied are those most likely to be impacted by climate change. We found research suffers from a strong geographic bias, with only 3.5\\% of studies occurring in the tropics. Importantly, the distribution of sites sampled under projected climate changes was biased?areas with decreases or large increases in precipitation and areas with low magnitudes of temperature change were under-represented. Our results suggest that understanding of climate change impacts on food webs could be broadened by considering more than two trophic levels, responses in addition to species abundance and biomass, impacts of a wider suite of climatic variables, and tropical ecosystems. Most importantly, to enable better forecasts of biodiversity responses to climate change, we identify critically under-represented geographic regions and climatic conditions which should be prioritized in future research.},\n\tnumber = {3},\n\turldate = {2019-11-05},\n\tjournal = {Ecosphere},\n\tauthor = {Cameron, Erin K. and Sundqvist, Maja K. and Keith, Sally A. and CaraDonna, Paul J. and Mousing, Erik A. and Nilsson, Karin A. and Metcalfe, Daniel B. and Classen, Aimée T.},\n\tmonth = mar,\n\tyear = {2019},\n\tkeywords = {\\#nosource, aquatic, climate change, data gaps, extreme events, food webs, freshwater, global, marine, precipitation, species interactions, terrestrial, warming},\n\tpages = {e02645},\n}\n\n\n\n\n\n Abstract Trophic interactions within food webs affect species distributions, coexistence, and provision of ecosystem services but can be strongly impacted by climatic changes. Understanding these impacts is therefore essential for managing ecosystems and sustaining human well-being. Here, we conducted a global synthesis of terrestrial, marine, and freshwater studies to identify key gaps in our knowledge of climate change impacts on food webs and determine whether the areas currently studied are those most likely to be impacted by climate change. We found research suffers from a strong geographic bias, with only 3.5% of studies occurring in the tropics. Importantly, the distribution of sites sampled under projected climate changes was biased?areas with decreases or large increases in precipitation and areas with low magnitudes of temperature change were under-represented. Our results suggest that understanding of climate change impacts on food webs could be broadened by considering more than two trophic levels, responses in addition to species abundance and biomass, impacts of a wider suite of climatic variables, and tropical ecosystems. Most importantly, to enable better forecasts of biodiversity responses to climate change, we identify critically under-represented geographic regions and climatic conditions which should be prioritized in future research.\n
\n\n\n\n \n\n \n \n \n \n \n \n Experimental evidence of the long-term effects of reindeer on Arctic vegetation greenness and species richness at a larger landscape scale.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Moen, J.; Björk, R. G.; Vowles, T.; Kytöviita, M.; Parsons, M. A.; and Olofsson, J.\n\n\n \n\n\n\n Journal of Ecology, 107(6): 2724–2736. 2019.\n \n\n\n\n
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\n\n\n@article{sundqvist_experimental_2019,\n\ttitle = {Experimental evidence of the long-term effects of reindeer on {Arctic} vegetation greenness and species richness at a larger landscape scale},\n\tvolume = {107},\n\tcopyright = {© 2019 The Authors. Journal of Ecology © 2019 British Ecological Society},\n\tissn = {1365-2745},\n\turl = {http://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.13201},\n\tdoi = {10.1111/1365-2745.13201},\n\tabstract = {Large herbivores influence plant community structure and ecosystem processes in many ecosystems. In large parts of the Arctic, reindeer (or caribou) are the only large herbivores present. Recent studies show that reindeer have the potential to mitigate recent warming-induced shrub encroachment in the Arctic and the associated greening of high-latitude ecosystems. This will potentially have large scale consequences for ecosystem productivity and carbon cycling. To date, information on variation in the interactions between reindeer and plants across Arctic landscapes has been scarce. We utilized a network of experimental sites across a latitudinal gradient in the Scandinavian mountains where reindeer have been excluded from 59 study plots for at least 15 years. We used this study system to test the effect of long-term exclusion of reindeer on the abundance of major plant functional groups, the greenness indexes Leaf Area Index (LAI) and Normalized Difference Vegetation Index (NDVI), soil mineral nitrogen (N) and phosphorous (P), and species richness, and to determine whether the effect of reindeer exclusion is dependent on reindeer density, productivity, soil fertility or climate. We found that NDVI and LAI, lichen and deciduous shrub abundances were largely reduced while soil mineral N was enhanced by reindeer. The direction and amplitude of other plant functional group responses to reindeer exclusion differed between forest and tundra as well as shrub- and herbaceous-dominated vegetation. Higher reindeer densities were related to decreased plant species richness in low-productive sites and to increased species richness in productive sites. The relative reduction in LAI and associated absolute reductions of deciduous shrubs in response to reindeer were positively related to reindeer density, while the relative reduction in NDVI was not. Further, relative reductions in LAI and NDVI in response to reindeer were unrelated to climate and soil fertility. Synthesis. Our results provide long-term experimental evidence highlighting the role of reindeer density in regulating plant species richness, global climate change induced greenness patterns and shrub encroachment at regional scales in the Arctic. These findings emphasize the need to consider reindeer in models predicting vegetation patterns and changes in high-latitude ecosystems.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2019-11-05},\n\tjournal = {Journal of Ecology},\n\tauthor = {Sundqvist, Maja K. and Moen, Jon and Björk, Robert G. and Vowles, Tage and Kytöviita, Minna-Maarit and Parsons, Malcolm A. and Olofsson, Johan},\n\tyear = {2019},\n\tkeywords = {\\#nosource, climate change, forest, grazing, large mammalian herbivores, plant community composition, plant–herbivore interactions, soil nutrients, tundra},\n\tpages = {2724--2736},\n}\n\n\n\n\n\n Large herbivores influence plant community structure and ecosystem processes in many ecosystems. In large parts of the Arctic, reindeer (or caribou) are the only large herbivores present. Recent studies show that reindeer have the potential to mitigate recent warming-induced shrub encroachment in the Arctic and the associated greening of high-latitude ecosystems. This will potentially have large scale consequences for ecosystem productivity and carbon cycling. To date, information on variation in the interactions between reindeer and plants across Arctic landscapes has been scarce. We utilized a network of experimental sites across a latitudinal gradient in the Scandinavian mountains where reindeer have been excluded from 59 study plots for at least 15 years. We used this study system to test the effect of long-term exclusion of reindeer on the abundance of major plant functional groups, the greenness indexes Leaf Area Index (LAI) and Normalized Difference Vegetation Index (NDVI), soil mineral nitrogen (N) and phosphorous (P), and species richness, and to determine whether the effect of reindeer exclusion is dependent on reindeer density, productivity, soil fertility or climate. We found that NDVI and LAI, lichen and deciduous shrub abundances were largely reduced while soil mineral N was enhanced by reindeer. The direction and amplitude of other plant functional group responses to reindeer exclusion differed between forest and tundra as well as shrub- and herbaceous-dominated vegetation. Higher reindeer densities were related to decreased plant species richness in low-productive sites and to increased species richness in productive sites. The relative reduction in LAI and associated absolute reductions of deciduous shrubs in response to reindeer were positively related to reindeer density, while the relative reduction in NDVI was not. Further, relative reductions in LAI and NDVI in response to reindeer were unrelated to climate and soil fertility. Synthesis. Our results provide long-term experimental evidence highlighting the role of reindeer density in regulating plant species richness, global climate change induced greenness patterns and shrub encroachment at regional scales in the Arctic. These findings emphasize the need to consider reindeer in models predicting vegetation patterns and changes in high-latitude ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Photo-reactivity of dissolved organic carbon in the freshwater continuum.\n \n \n \n \n\n\n \n Panneer Selvam, B.; Lapierre, J.; Soares, A. R. A.; Bastviken, D.; Karlsson, J.; and Berggren, M.\n\n\n \n\n\n\n Aquatic Sciences, 81(4): 57. July 2019.\n \n\n\n\n
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\n\n\n@article{panneer_selvam_photo-reactivity_2019,\n\ttitle = {Photo-reactivity of dissolved organic carbon in the freshwater continuum},\n\tvolume = {81},\n\tissn = {1420-9055},\n\turl = {https://doi.org/10.1007/s00027-019-0653-0},\n\tdoi = {10.1007/s00027-019-0653-0},\n\tabstract = {The patterns in dissolved organic carbon (DOC) photo-mineralization along the freshwater continuum from land to sea are poorly known. Specifically, it has not been resolved how the photo-degradation of DOC into CO2 (PD) depends on the combination of intrinsic properties of DOC and extrinsic variables that affect the photo-reactions. We measured PD per unit of absorbed ultraviolet light energy (PD-Ew) in headwater streams, lakes, intermediate rivers and river mouths in Sweden. Surprisingly, no trend of decreasing PD-Ew was found with decreases in colored DOC. However, there was a relationship between PD-Ew and pH, best described by a quadratic (U-shaped) curve, indicating environmental control of photo-reactivity. Interestingly, the highest values for both of these variables were recorded for river mouths. Moreover, PD-Ew increased with proxy variables for the amount of autochthonous DOC in the water. Thus, changes in pH and autochthonous DOC input along the continuum may sustain high DOC photo-mineralization throughout continental aquatic networks.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2019-07-30},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Panneer Selvam, Balathandayuthabani and Lapierre, Jean-François and Soares, Ana R. A. and Bastviken, David and Karlsson, Jan and Berggren, Martin},\n\tmonth = jul,\n\tyear = {2019},\n\tkeywords = {\\#nosource, Colored dissolved organic matter, Dissolved organic carbon, Freshwater systems, Photo-reactivity, pH},\n\tpages = {57},\n}\n\n\n\n\n\n The patterns in dissolved organic carbon (DOC) photo-mineralization along the freshwater continuum from land to sea are poorly known. Specifically, it has not been resolved how the photo-degradation of DOC into CO2 (PD) depends on the combination of intrinsic properties of DOC and extrinsic variables that affect the photo-reactions. We measured PD per unit of absorbed ultraviolet light energy (PD-Ew) in headwater streams, lakes, intermediate rivers and river mouths in Sweden. Surprisingly, no trend of decreasing PD-Ew was found with decreases in colored DOC. However, there was a relationship between PD-Ew and pH, best described by a quadratic (U-shaped) curve, indicating environmental control of photo-reactivity. Interestingly, the highest values for both of these variables were recorded for river mouths. Moreover, PD-Ew increased with proxy variables for the amount of autochthonous DOC in the water. Thus, changes in pH and autochthonous DOC input along the continuum may sustain high DOC photo-mineralization throughout continental aquatic networks.\n
\n\n\n\n \n\n \n \n \n \n \n \n Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation.\n \n \n \n \n\n\n \n Shirokova, L. S.; Chupakov, A. V.; Zabelina, S. A.; Neverova, N. V.; Payandi-Rolland, D.; Causserand, C.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Biogeosciences, 16(12): 2511–2526. June 2019.\n \n\n\n\n
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\n\n\n@article{shirokova_humic_2019,\n\ttitle = {Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation},\n\tvolume = {16},\n\tissn = {1726-4170},\n\turl = {https://www.biogeosciences.net/16/2511/2019/},\n\tdoi = {10.5194/bg-16-2511-2019},\n\tabstract = {{\\textless}p{\\textgreater}{\\textless}strong{\\textgreater}Abstract.{\\textless}/strong{\\textgreater} In contrast to the large number of studies on humic waters from permafrost-free regions and oligotrophic waters from permafrost-bearing regions, the bio- and photolability of DOM from the humic surface waters of permafrost-bearing regions has not been thoroughly evaluated. Following standardized protocol, we measured biodegradation (at low, intermediate and high temperatures) and photodegradation (at one intermediate temperature) of DOM in surface waters along the hydrological continuum (depression {\\textless}span class="inline-formula"{\\textgreater}→{\\textless}/span{\\textgreater} stream {\\textless}span class="inline-formula"{\\textgreater}→{\\textless}/span{\\textgreater} thermokarst lake {\\textless}span class="inline-formula"{\\textgreater}→{\\textless}/span{\\textgreater} Pechora River) within a frozen peatland in European Russia. In all systems, within the experimental resolution of 5\\ \\% to 10\\ \\%, there was no bio- or photodegradation of DOM over a 1-month incubation period. It is possible that the main cause of the lack of degradation is the dominance of allochthonous refractory (soil, peat) DOM in all waters studied. However, all surface waters were supersaturated with {\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater}. Thus, this study suggests that, rather than bio- and photodegradation of DOM in the water column, other factors such as peat pore-water DOM processing and respiration of sediments are the main drivers of elevated {\\textless}span class="inline-formula"{\\textgreater}\\textit{p}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater} and {\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater} emission in humic boreal waters of frozen peat bogs.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\tnumber = {12},\n\turldate = {2019-07-30},\n\tjournal = {Biogeosciences},\n\tauthor = {Shirokova, Liudmila S. and Chupakov, Artem V. and Zabelina, Svetlana A. and Neverova, Natalia V. and Payandi-Rolland, Dahedrey and Causserand, Carole and Karlsson, Jan and Pokrovsky, Oleg S.},\n\tmonth = jun,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {2511--2526},\n}\n\n\n\n\n\n \\textlessp\\textgreater\\textlessstrong\\textgreaterAbstract.\\textless/strong\\textgreater In contrast to the large number of studies on humic waters from permafrost-free regions and oligotrophic waters from permafrost-bearing regions, the bio- and photolability of DOM from the humic surface waters of permafrost-bearing regions has not been thoroughly evaluated. Following standardized protocol, we measured biodegradation (at low, intermediate and high temperatures) and photodegradation (at one intermediate temperature) of DOM in surface waters along the hydrological continuum (depression \\textlessspan class=\"inline-formula\"\\textgreater→\\textless/span\\textgreater stream \\textlessspan class=\"inline-formula\"\\textgreater→\\textless/span\\textgreater thermokarst lake \\textlessspan class=\"inline-formula\"\\textgreater→\\textless/span\\textgreater Pechora River) within a frozen peatland in European Russia. In all systems, within the experimental resolution of 5 % to 10 %, there was no bio- or photodegradation of DOM over a 1-month incubation period. It is possible that the main cause of the lack of degradation is the dominance of allochthonous refractory (soil, peat) DOM in all waters studied. However, all surface waters were supersaturated with \\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater. Thus, this study suggests that, rather than bio- and photodegradation of DOM in the water column, other factors such as peat pore-water DOM processing and respiration of sediments are the main drivers of elevated \\textlessspan class=\"inline-formula\"\\textgreaterpCO$_{\\textrm{2}}$\\textless/span\\textgreater and \\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater emission in humic boreal waters of frozen peat bogs.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n Trouble brewing?.\n \n \n \n \n\n\n \n Ogden, L. E.\n\n\n \n\n\n\n New Scientist, 242(3233): 42–43. June 2019.\n \n\n\n\n
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\n\n\n@article{ogden_trouble_2019,\n\ttitle = {Trouble brewing?},\n\tvolume = {242},\n\tissn = {0262-4079},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0262407919310371},\n\tdoi = {10.1016/S0262-4079(19)31037-1},\n\tabstract = {An ingenious experiment is using the humble teabag to probe worrying carbon emissions in the Arctic, finds Lesley Evans Ogden},\n\tlanguage = {en},\n\tnumber = {3233},\n\turldate = {2020-03-19},\n\tjournal = {New Scientist},\n\tauthor = {Ogden, Lesley Evans},\n\tmonth = jun,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {42--43},\n}\n\n\n\n\n\n An ingenious experiment is using the humble teabag to probe worrying carbon emissions in the Arctic, finds Lesley Evans Ogden\n
\n\n\n\n \n\n \n \n \n \n \n \n Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome.\n \n \n \n \n\n\n \n Rheubottom, S. I.; Barrio, I. C.; Kozlov, M. V.; Alatalo, J. M.; Andersson, T.; Asmus, A. L.; Baubin, C.; Brearley, F. Q.; Egelkraut, D. D.; Ehrich, D.; Gauthier, G.; Jónsdóttir, I. S.; Konieczka, S.; Lévesque, E.; Olofsson, J.; Prevéy, J. S.; Slevan-Tremblay, G.; Sokolov, A.; Sokolova, N.; Sokovnina, S.; Speed, J. D. M.; Suominen, O.; Zverev, V.; and Hik, D. S.\n\n\n \n\n\n\n Polar Biology, 42(10): 1881–1897. October 2019.\n \n\n\n\n
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\n\n\n@article{rheubottom_hiding_2019,\n\ttitle = {Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome},\n\tvolume = {42},\n\tissn = {1432-2056},\n\tshorttitle = {Hiding in the background},\n\turl = {https://doi.org/10.1007/s00300-019-02568-3},\n\tdoi = {10.1007/s00300-019-02568-3},\n\tabstract = {Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and year-of-sampling weather, habitat characteristics, and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94\\% and ranging between 0.02 and 5.69\\% of plant biomass. Our results suggest that mid-summer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2020-03-19},\n\tjournal = {Polar Biology},\n\tauthor = {Rheubottom, Sarah I. and Barrio, Isabel C. and Kozlov, Mikhail V. and Alatalo, Juha M. and Andersson, Tommi and Asmus, Ashley L. and Baubin, Capucine and Brearley, Francis Q. and Egelkraut, Dagmar D. and Ehrich, Dorothee and Gauthier, Gilles and Jónsdóttir, Ingibjörg Svala and Konieczka, Sophia and Lévesque, Esther and Olofsson, Johan and Prevéy, Janet S. and Slevan-Tremblay, Guillaume and Sokolov, Aleksandr and Sokolova, Natalia and Sokovnina, Svetlana and Speed, James D. M. and Suominen, Otso and Zverev, Vitali and Hik, David S.},\n\tmonth = oct,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {1881--1897},\n}\n\n\n\n\n\n Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and year-of-sampling weather, habitat characteristics, and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant biomass. Our results suggest that mid-summer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Impact of structural habitat modifications in coastal temperate systems on fish recruitment: a systematic review.\n \n \n \n \n\n\n \n Macura, B.; Byström, P.; Airoldi, L.; Eriksson, B. K.; Rudstam, L.; and Støttrup, J. G.\n\n\n \n\n\n\n Environmental Evidence, 8(1): 14. March 2019.\n \n\n\n\n
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\n\n\n@article{macura_impact_2019,\n\ttitle = {Impact of structural habitat modifications in coastal temperate systems on fish recruitment: a systematic review},\n\tvolume = {8},\n\tissn = {2047-2382},\n\tshorttitle = {Impact of structural habitat modifications in coastal temperate systems on fish recruitment},\n\turl = {https://doi.org/10.1186/s13750-019-0157-3},\n\tdoi = {10.1186/s13750-019-0157-3},\n\tabstract = {Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. As a result, an increasing number of structural modifications occur in coastal nursery and spawning habitats of fish. Concomitant to this increase, there have been declines in many coastal fish populations and changes in the composition of fish communities. As requested by Swedish stakeholders, this review aimed to synthesise scientific evidence of the impact on fish recruitment of structural modifications in temperate coastal areas.},\n\tnumber = {1},\n\turldate = {2020-03-19},\n\tjournal = {Environmental Evidence},\n\tauthor = {Macura, Biljana and Byström, Pär and Airoldi, Laura and Eriksson, Britas Klemens and Rudstam, Lars and Støttrup, Josianne G.},\n\tmonth = mar,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {14},\n}\n\n\n\n\n\n Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. As a result, an increasing number of structural modifications occur in coastal nursery and spawning habitats of fish. Concomitant to this increase, there have been declines in many coastal fish populations and changes in the composition of fish communities. As requested by Swedish stakeholders, this review aimed to synthesise scientific evidence of the impact on fish recruitment of structural modifications in temperate coastal areas.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global distribution of earthworm diversity.\n \n \n \n \n\n\n \n Phillips, H. R. P.; Guerra, C. A.; Bartz, M. L. C.; Briones, M. J. I.; Brown, G.; Crowther, T. W.; Ferlian, O.; Gongalsky, K. B.; van den Hoogen, J.; Krebs, J.; Orgiazzi, A.; Routh, D.; Schwarz, B.; Bach, E. M.; Bennett, J.; Brose, U.; Decaëns, T.; König-Ries, B.; Loreau, M.; Mathieu, J.; Mulder, C.; van der Putten, W. H.; Ramirez, K. S.; Rillig, M. C.; Russell, D.; Rutgers, M.; Thakur, M. P.; de Vries, F. T.; Wall, D. H.; Wardle, D. A.; Arai, M.; Ayuke, F. O.; Baker, G. H.; Beauséjour, R.; Bedano, J. C.; Birkhofer, K.; Blanchart, E.; Blossey, B.; Bolger, T.; Bradley, R. L.; Callaham, M. A.; Capowiez, Y.; Caulfield, M. E.; Choi, A.; Crotty, F. V.; Dávalos, A.; Cosin, D. J. D.; Dominguez, A.; Duhour, A. E.; van Eekeren, N.; Emmerling, C.; Falco, L. B.; Fernández, R.; Fonte, S. J.; Fragoso, C.; Franco, A. L. C.; Fugère, M.; Fusilero, A. T.; Gholami, S.; Gundale, M. J.; López, M. G.; Hackenberger, D. K.; Hernández, L. M.; Hishi, T.; Holdsworth, A. R.; Holmstrup, M.; Hopfensperger, K. N.; Lwanga, E. H.; Huhta, V.; Hurisso, T. T.; Iannone, B. V.; Iordache, M.; Joschko, M.; Kaneko, N.; Kanianska, R.; Keith, A. M.; Kelly, C. A.; Kernecker, M. L.; Klaminder, J.; Koné, A. W.; Kooch, Y.; Kukkonen, S. T.; Lalthanzara, H.; Lammel, D. R.; Lebedev, I. M.; Li, Y.; Lidon, J. B. J.; Lincoln, N. K.; Loss, S. R.; Marichal, R.; Matula, R.; Moos, J. H.; Moreno, G.; Morón-Ríos, A.; Muys, B.; Neirynck, J.; Norgrove, L.; Novo, M.; Nuutinen, V.; Nuzzo, V.; Rahman P, M.; Pansu, J.; Paudel, S.; Pérès, G.; Pérez-Camacho, L.; Piñeiro, R.; Ponge, J.; Rashid, M. I.; Rebollo, S.; Rodeiro-Iglesias, J.; Rodríguez, M. Á.; Roth, A. M.; Rousseau, G. X.; Rozen, A.; Sayad, E.; van Schaik, L.; Scharenbroch, B. C.; Schirrmann, M.; Schmidt, O.; Schröder, B.; Seeber, J.; Shashkov, M. P.; Singh, J.; Smith, S. M.; Steinwandter, M.; Talavera, J. A.; Trigo, D.; Tsukamoto, J.; de Valença, A. W.; Vanek, S. J.; Virto, I.; Wackett, A. A.; Warren, M. W.; Wehr, N. H.; Whalen, J. K.; Wironen, M. B.; Wolters, V.; Zenkova, I. V.; Zhang, W.; Cameron, E. K.; and Eisenhauer, N.\n\n\n \n\n\n\n Science, 366(6464): 480–485. October 2019.\n \n\n\n\n
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\n\n\n\n@article{phillips_global_2019,\n\ttitle = {Global distribution of earthworm diversity},\n\tvolume = {366},\n\tissn = {0036-8075, 1095-9203},\n\turl = {https://www.sciencemag.org/lookup/doi/10.1126/science.aax4851},\n\tdoi = {10.1126/science.aax4851},\n\tlanguage = {en},\n\tnumber = {6464},\n\turldate = {2020-03-19},\n\tjournal = {Science},\n\tauthor = {Phillips, Helen R. P. and Guerra, Carlos A. and Bartz, Marie L. C. and Briones, Maria J. I. and Brown, George and Crowther, Thomas W. and Ferlian, Olga and Gongalsky, Konstantin B. and van den Hoogen, Johan and Krebs, Julia and Orgiazzi, Alberto and Routh, Devin and Schwarz, Benjamin and Bach, Elizabeth M. and Bennett, Joanne and Brose, Ulrich and Decaëns, Thibaud and König-Ries, Birgitta and Loreau, Michel and Mathieu, Jérôme and Mulder, Christian and van der Putten, Wim H. and Ramirez, Kelly S. and Rillig, Matthias C. and Russell, David and Rutgers, Michiel and Thakur, Madhav P. and de Vries, Franciska T. and Wall, Diana H. and Wardle, David A. and Arai, Miwa and Ayuke, Fredrick O. and Baker, Geoff H. and Beauséjour, Robin and Bedano, José C. and Birkhofer, Klaus and Blanchart, Eric and Blossey, Bernd and Bolger, Thomas and Bradley, Robert L. and Callaham, Mac A. and Capowiez, Yvan and Caulfield, Mark E. and Choi, Amy and Crotty, Felicity V. and Dávalos, Andrea and Cosin, Darío J. Diaz and Dominguez, Anahí and Duhour, Andrés Esteban and van Eekeren, Nick and Emmerling, Christoph and Falco, Liliana B. and Fernández, Rosa and Fonte, Steven J. and Fragoso, Carlos and Franco, André L. C. and Fugère, Martine and Fusilero, Abegail T. and Gholami, Shaieste and Gundale, Michael J. and López, Mónica Gutiérrez and Hackenberger, Davorka K. and Hernández, Luis M. and Hishi, Takuo and Holdsworth, Andrew R. and Holmstrup, Martin and Hopfensperger, Kristine N. and Lwanga, Esperanza Huerta and Huhta, Veikko and Hurisso, Tunsisa T. and Iannone, Basil V. and Iordache, Madalina and Joschko, Monika and Kaneko, Nobuhiro and Kanianska, Radoslava and Keith, Aidan M. and Kelly, Courtland A. and Kernecker, Maria L. and Klaminder, Jonatan and Koné, Armand W. and Kooch, Yahya and Kukkonen, Sanna T. and Lalthanzara, H. and Lammel, Daniel R. and Lebedev, Iurii M. and Li, Yiqing and Lidon, Juan B. Jesus and Lincoln, Noa K. and Loss, Scott R. and Marichal, Raphael and Matula, Radim and Moos, Jan Hendrik and Moreno, Gerardo and Morón-Ríos, Alejandro and Muys, Bart and Neirynck, Johan and Norgrove, Lindsey and Novo, Marta and Nuutinen, Visa and Nuzzo, Victoria and Rahman P, Mujeeb and Pansu, Johan and Paudel, Shishir and Pérès, Guénola and Pérez-Camacho, Lorenzo and Piñeiro, Raúl and Ponge, Jean-François and Rashid, Muhammad Imtiaz and Rebollo, Salvador and Rodeiro-Iglesias, Javier and Rodríguez, Miguel Á. and Roth, Alexander M. and Rousseau, Guillaume X. and Rozen, Anna and Sayad, Ehsan and van Schaik, Loes and Scharenbroch, Bryant C. and Schirrmann, Michael and Schmidt, Olaf and Schröder, Boris and Seeber, Julia and Shashkov, Maxim P. and Singh, Jaswinder and Smith, Sandy M. and Steinwandter, Michael and Talavera, José A. and Trigo, Dolores and Tsukamoto, Jiro and de Valença, Anne W. and Vanek, Steven J. and Virto, Iñigo and Wackett, Adrian A. and Warren, Matthew W. and Wehr, Nathaniel H. and Whalen, Joann K. and Wironen, Michael B. and Wolters, Volkmar and Zenkova, Irina V. and Zhang, Weixin and Cameron, Erin K. and Eisenhauer, Nico},\n\tmonth = oct,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {480--485},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Partitioning spatial, environmental, and community drivers of ecosystem functioning.\n \n \n \n \n\n\n \n Truchy, A.; Göthe, E.; Angeler, D. G.; Ecke, F.; Sponseller, R. A.; Bundschuh, M.; Johnson, R. K.; and McKie, B. G.\n\n\n \n\n\n\n Landscape Ecology, 34(10): 2371–2384. October 2019.\n \n\n\n\n
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\n\n\n@article{truchy_partitioning_2019,\n\ttitle = {Partitioning spatial, environmental, and community drivers of ecosystem functioning},\n\tvolume = {34},\n\tissn = {1572-9761},\n\turl = {https://doi.org/10.1007/s10980-019-00894-9},\n\tdoi = {10.1007/s10980-019-00894-9},\n\tabstract = {Community composition, environmental variation, and spatial structuring can influence ecosystem functioning, and ecosystem service delivery. While the role of space in regulating ecosystem functioning is well recognised in theory, it is rarely considered explicitly in empirical studies.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2020-03-19},\n\tjournal = {Landscape Ecology},\n\tauthor = {Truchy, Amélie and Göthe, Emma and Angeler, David G. and Ecke, Frauke and Sponseller, Ryan A. and Bundschuh, Mirco and Johnson, Richard K. and McKie, Brendan G.},\n\tmonth = oct,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {2371--2384},\n}\n\n\n\n\n\n Community composition, environmental variation, and spatial structuring can influence ecosystem functioning, and ecosystem service delivery. While the role of space in regulating ecosystem functioning is well recognised in theory, it is rarely considered explicitly in empirical studies.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting responses in dissolved organic carbon to extreme climate events from adjacent boreal landscapes in Northern Sweden.\n \n \n \n \n\n\n \n Tiwari, T.; Sponseller, R. A; and Laudon, H.\n\n\n \n\n\n\n Environmental Research Letters, 14(8): 084007. July 2019.\n \n\n\n\n
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\n\n\n\n@article{tiwari_contrasting_2019,\n\ttitle = {Contrasting responses in dissolved organic carbon to extreme climate events from adjacent boreal landscapes in {Northern} {Sweden}},\n\tvolume = {14},\n\tissn = {1748-9326},\n\turl = {https://iopscience.iop.org/article/10.1088/1748-9326/ab23d4},\n\tdoi = {10.1088/1748-9326/ab23d4},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2020-03-19},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Tiwari, Tejshree and Sponseller, Ryan A and Laudon, Hjalmar},\n\tmonth = jul,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {084007},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Bromoanisoles and methoxylated bromodiphenyl ethers in macroalgae from Nordic coastal regions.\n \n \n \n \n\n\n \n Bidleman, T. F.; Andersson, A.; Brugel, S.; Ericson, L.; Haglund, P.; Kupryianchyk, D.; Lau, D. C. P.; Liljelind, P.; Lundin, L.; Tysklind, A.; and Tysklind, M.\n\n\n \n\n\n\n Environmental Science: Processes & Impacts, 21(5): 881–892. 2019.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{bidleman_bromoanisoles_2019,\n\ttitle = {Bromoanisoles and methoxylated bromodiphenyl ethers in macroalgae from {Nordic} coastal regions},\n\tvolume = {21},\n\tissn = {2050-7887, 2050-7895},\n\turl = {http://xlink.rsc.org/?DOI=C9EM00042A},\n\tdoi = {10.1039/C9EM00042A},\n\tabstract = {The content of bromoanisoles and methoxylated bromodiphenyl ethers varies by orders of magnitude among sixteen species of macroalgae collected from Nordic coastal waters.\n , \n \n Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products (HNPs), some of which have toxic properties similar to those of well-known anthropogenic contaminants. Sixteen species of red, green and brown macroalgae were collected in 2017–2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analyzed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Target compounds were quantified by gas chromatography-low resolution mass spectrometry (GC-LRMS), with qualitative confirmation in selected species by GC-high resolution mass spectrometry (GC-HRMS). Quantified compounds were 2,4-diBA, 2,4,6-triBA, 2′-MeO-BDE68, 6-MeO-BDE47, and two tribromo-MeO-BDEs and one tetrabromo-MeO-BDE with unknown bromine substituent positions. Semiquantitative results for pentabromo-MeO-BDEs were also obtained for a few species by GC-HRMS. Three extraction methods were compared; soaking in methanol, soaking in methanol–dichloromethane, and blending with mixed solvents. Extraction yields of BAs did not differ significantly (\n p\n {\\textgreater} 0.05) with the three methods and the two soaking methods gave equivalent yields of MeO-BDEs. Extraction efficiencies of MeO-BDEs were significantly lower using the blend method (\n p\n {\\textless} 0.05). For reasons of simplicity and efficiency, the soaking methods are preferred. Concentrations varied by orders of magnitude among species: ∑\n 2\n BAs 57 to 57 700 and ∑\n 5\n MeO-BDEs {\\textless} 10 to 476 pg g\n −1\n wet weight (ww). Macroalgae standing out with ∑\n 2\n BAs {\\textgreater}1000 pg g\n −1\n ww were\n Ascophyllum nodosum\n ,\n Ceramium tenuicorne\n ,\n Ceramium virgatum\n ,\n Fucus radicans\n ,\n Fucus serratus\n ,\n Fucus vesiculosus\n ,\n Saccharina latissima\n ,\n Laminaria digitata\n , and\n Acrosiphonia/Spongomorpha\n sp. Species\n A. nodosum\n ,\n C. tenuicorne\n ,\n Chara virgata\n ,\n F. radicans\n and\n F. vesiculosus\n (Sweden Atlantic only) had ∑\n 5\n MeO-BDEs {\\textgreater}100 pg g\n −1\n ww. Profiles of individual compounds showed distinct differences among species and locations.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2020-03-19},\n\tjournal = {Environmental Science: Processes \\& Impacts},\n\tauthor = {Bidleman, Terry F. and Andersson, Agneta and Brugel, Sonia and Ericson, Lars and Haglund, Peter and Kupryianchyk, Darya and Lau, Danny C. P. and Liljelind, Per and Lundin, Lisa and Tysklind, Anders and Tysklind, Mats},\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {881--892},\n}\n\n\n\n\n\n The content of bromoanisoles and methoxylated bromodiphenyl ethers varies by orders of magnitude among sixteen species of macroalgae collected from Nordic coastal waters. , Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products (HNPs), some of which have toxic properties similar to those of well-known anthropogenic contaminants. Sixteen species of red, green and brown macroalgae were collected in 2017–2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analyzed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Target compounds were quantified by gas chromatography-low resolution mass spectrometry (GC-LRMS), with qualitative confirmation in selected species by GC-high resolution mass spectrometry (GC-HRMS). Quantified compounds were 2,4-diBA, 2,4,6-triBA, 2′-MeO-BDE68, 6-MeO-BDE47, and two tribromo-MeO-BDEs and one tetrabromo-MeO-BDE with unknown bromine substituent positions. Semiquantitative results for pentabromo-MeO-BDEs were also obtained for a few species by GC-HRMS. Three extraction methods were compared; soaking in methanol, soaking in methanol–dichloromethane, and blending with mixed solvents. Extraction yields of BAs did not differ significantly ( p \\textgreater 0.05) with the three methods and the two soaking methods gave equivalent yields of MeO-BDEs. Extraction efficiencies of MeO-BDEs were significantly lower using the blend method ( p \\textless 0.05). For reasons of simplicity and efficiency, the soaking methods are preferred. Concentrations varied by orders of magnitude among species: ∑ 2 BAs 57 to 57 700 and ∑ 5 MeO-BDEs \\textless 10 to 476 pg g −1 wet weight (ww). Macroalgae standing out with ∑ 2 BAs \\textgreater1000 pg g −1 ww were Ascophyllum nodosum , Ceramium tenuicorne , Ceramium virgatum , Fucus radicans , Fucus serratus , Fucus vesiculosus , Saccharina latissima , Laminaria digitata , and Acrosiphonia/Spongomorpha sp. Species A. nodosum , C. tenuicorne , Chara virgata , F. radicans and F. vesiculosus (Sweden Atlantic only) had ∑ 5 MeO-BDEs \\textgreater100 pg g −1 ww. Profiles of individual compounds showed distinct differences among species and locations.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Effect of Stream Discharge on Hyporheic Exchange.\n \n \n \n \n\n\n \n Mojarrad, B. B.; Betterle, A.; Singh, T.; Olid, C.; and Wörman, A.\n\n\n \n\n\n\n Water, 11(7): 1436. July 2019.\n \n\n\n\n
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\n\n\n@article{mojarrad_effect_2019,\n\ttitle = {The {Effect} of {Stream} {Discharge} on {Hyporheic} {Exchange}},\n\tvolume = {11},\n\tissn = {2073-4441},\n\turl = {https://www.mdpi.com/2073-4441/11/7/1436},\n\tdoi = {10.3390/w11071436},\n\tabstract = {Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2019-07-30},\n\tjournal = {Water},\n\tauthor = {Mojarrad, Brian Babak and Betterle, Andrea and Singh, Tanu and Olid, Carolina and Wörman, Anders},\n\tmonth = jul,\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {1436},\n}\n\n\n\n\n\n Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Landscape process domains drive patterns of CO2 evasion from river networks.\n \n \n \n \n\n\n \n Rocher‐Ros, G.; Sponseller, R. A.; Lidberg, W.; Mörth, C.; and Giesler, R.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 4(4): 87–95. 2019.\n \n\n\n\n
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\n\n\n@article{rocherros_landscape_2019,\n\ttitle = {Landscape process domains drive patterns of {CO2} evasion from river networks},\n\tvolume = {4},\n\tcopyright = {© 2019 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.},\n\tissn = {2378-2242},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10108},\n\tdoi = {10.1002/lol2.10108},\n\tabstract = {Streams are important emitters of CO2 but extreme spatial variability in their physical properties can make upscaling very uncertain. Here, we determined critical drivers of stream CO2 evasion at scales from 30 to 400 m across a 52.5 km2 catchment in northern Sweden. We found that turbulent reaches never have elevated CO2 concentrations, while less turbulent locations can potentially support a broad range of CO2 concentrations, consistent with global observations. The predictability of stream pCO2 is greatly improved when we include a proxy for soil-stream connectivity. Catchment topography shapes network patterns of evasion by creating hydrologically linked “domains” characterized by high water-atmosphere exchange and/or strong soil-stream connection. This template generates spatial variability in the drivers of CO2 evasion that can strongly bias regional and global estimates. To overcome this complexity, we provide the foundations of a mechanistic framework of CO2 evasion by considering how landscape process domains regulate transfer and supply.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2019-08-30},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Rocher‐Ros, Gerard and Sponseller, Ryan A. and Lidberg, William and Mörth, Carl-Magnus and Giesler, Reiner},\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {87--95},\n}\n\n\n\n\n\n Streams are important emitters of CO2 but extreme spatial variability in their physical properties can make upscaling very uncertain. Here, we determined critical drivers of stream CO2 evasion at scales from 30 to 400 m across a 52.5 km2 catchment in northern Sweden. We found that turbulent reaches never have elevated CO2 concentrations, while less turbulent locations can potentially support a broad range of CO2 concentrations, consistent with global observations. The predictability of stream pCO2 is greatly improved when we include a proxy for soil-stream connectivity. Catchment topography shapes network patterns of evasion by creating hydrologically linked “domains” characterized by high water-atmosphere exchange and/or strong soil-stream connection. This template generates spatial variability in the drivers of CO2 evasion that can strongly bias regional and global estimates. To overcome this complexity, we provide the foundations of a mechanistic framework of CO2 evasion by considering how landscape process domains regulate transfer and supply.\n
\n\n\n\n \n\n \n \n \n \n \n \n Homogenization of freshwater lakes: Recent compositional shifts in fish communities are explained by gamefish movement and not climate change.\n \n \n \n \n\n\n \n Cazelles, K.; Bartley, T.; Guzzo, M. M.; Brice, M.; MacDougall, A. S.; Bennett, J. R.; Esch, E. H.; Kadoya, T.; Kelly, J.; Matsuzaki, S.; Nilsson, K. A.; and McCann, K. S.\n\n\n \n\n\n\n Global Change Biology, 25(12): 4222–4233. 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14829\n\n\n\n
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\n\n\n@article{cazelles_homogenization_2019,\n\ttitle = {Homogenization of freshwater lakes: {Recent} compositional shifts in fish communities are explained by gamefish movement and not climate change},\n\tvolume = {25},\n\tcopyright = {© 2019 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\tshorttitle = {Homogenization of freshwater lakes},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14829},\n\tdoi = {10.1111/gcb.14829},\n\tabstract = {Globally, lake fish communities are being subjected to a range of scale-dependent anthropogenic pressures, from climate change to eutrophication, and from overexploitation to species introductions. As a consequence, the composition of these communities is being reshuffled, in most cases leading to a surge in taxonomic similarity at the regional scale termed homogenization. The drivers of homogenization remain unclear, which may be a reflection of interactions between various environmental changes. In this study, we investigate two potential drivers of the recent changes in the composition of freshwater fish communities: recreational fishing and climate change. Our results, derived from 524 lakes of Ontario, Canada sampled in two periods (1965–1982 and 2008–2012), demonstrate that the main contributors to homogenization are the dispersal of gamefish species, most of which are large predators. Alternative explanations relating to lake habitat (e.g., area, phosphorus) or variations in climate have limited explanatory power. Our analysis suggests that human-assisted migration is the primary driver of the observed compositional shifts, homogenizing freshwater fish community among Ontario lakes and generating food webs dominated by gamefish species.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2020-04-23},\n\tjournal = {Global Change Biology},\n\tauthor = {Cazelles, Kevin and Bartley, Timothy and Guzzo, Matthew M. and Brice, Marie-Hélène and MacDougall, Andrew S. and Bennett, Joseph R. and Esch, Ellen H. and Kadoya, Taku and Kelly, Jocelyn and Matsuzaki, Shin-ichiro and Nilsson, Karin A. and McCann, Kevin S.},\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14829},\n\tkeywords = {\\#nosource, Ontario, angling pressure, climate change, compositional shift, fresh lake fish communities, homogenization, predatory fish},\n\tpages = {4222--4233},\n}\n\n\n\n\n\n Globally, lake fish communities are being subjected to a range of scale-dependent anthropogenic pressures, from climate change to eutrophication, and from overexploitation to species introductions. As a consequence, the composition of these communities is being reshuffled, in most cases leading to a surge in taxonomic similarity at the regional scale termed homogenization. The drivers of homogenization remain unclear, which may be a reflection of interactions between various environmental changes. In this study, we investigate two potential drivers of the recent changes in the composition of freshwater fish communities: recreational fishing and climate change. Our results, derived from 524 lakes of Ontario, Canada sampled in two periods (1965–1982 and 2008–2012), demonstrate that the main contributors to homogenization are the dispersal of gamefish species, most of which are large predators. Alternative explanations relating to lake habitat (e.g., area, phosphorus) or variations in climate have limited explanatory power. Our analysis suggests that human-assisted migration is the primary driver of the observed compositional shifts, homogenizing freshwater fish community among Ontario lakes and generating food webs dominated by gamefish species.\n
\n\n\n\n \n\n \n \n \n \n \n \n The browning and re-browning of lakes: Divergent lake-water organic carbon trends linked to acid deposition and climate change.\n \n \n \n \n\n\n \n Meyer-Jacob, C.; Michelutti, N.; Paterson, A. M.; Cumming, B. F.; Keller, W. (.; and Smol, J. P.\n\n\n \n\n\n\n Scientific Reports, 9(1): 1–10. November 2019.\n Number: 1 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{meyer-jacob_browning_2019,\n\ttitle = {The browning and re-browning of lakes: {Divergent} lake-water organic carbon trends linked to acid deposition and climate change},\n\tvolume = {9},\n\tcopyright = {2019 The Author(s)},\n\tissn = {2045-2322},\n\tshorttitle = {The browning and re-browning of lakes},\n\turl = {https://www.nature.com/articles/s41598-019-52912-0},\n\tdoi = {10.1038/s41598-019-52912-0},\n\tabstract = {Dissolved organic carbon (DOC) concentrations and water colour are increasing in many inland waters across northern Europe and northeastern North America. This inland-water “browning” has profound physical, chemical and biological repercussions for aquatic ecosystems affecting water quality, biological community structures and aquatic productivity. Potential drivers of this “browning” trend are complex and include reductions in atmospheric acid deposition, changes in land use/cover, increased nitrogen deposition and climate change. However, because of the overlapping impacts of these stressors, their relative contributions to DOC dynamics remain unclear, and without appropriate long-term monitoring data, it has not been possible to determine whether the ongoing “browning” is unprecedented or simply a “re-browning” to pre-industrial DOC levels. Here, we demonstrate the long-term impacts of acid deposition and climate change on lake-water DOC concentrations in low and high acid-deposition areas using infrared spectroscopic techniques on {\\textasciitilde}200-year-long lake-sediment records from central Canada. We show that acid deposition suppressed naturally higher DOC concentrations during the 20th century, but that a “re-browning” of lakes is now occurring with emissions reductions in formerly high deposition areas. In contrast, in low deposition areas, climate change is forcing lakes towards new ecological states, as lake-water DOC concentrations now often exceed pre-industrial levels.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-04-23},\n\tjournal = {Scientific Reports},\n\tauthor = {Meyer-Jacob, Carsten and Michelutti, Neal and Paterson, Andrew M. and Cumming, Brian F. and Keller, Wendel (Bill) and Smol, John P.},\n\tmonth = nov,\n\tyear = {2019},\n\tnote = {Number: 1\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {1--10},\n}\n\n\n\n\n\n Dissolved organic carbon (DOC) concentrations and water colour are increasing in many inland waters across northern Europe and northeastern North America. This inland-water “browning” has profound physical, chemical and biological repercussions for aquatic ecosystems affecting water quality, biological community structures and aquatic productivity. Potential drivers of this “browning” trend are complex and include reductions in atmospheric acid deposition, changes in land use/cover, increased nitrogen deposition and climate change. However, because of the overlapping impacts of these stressors, their relative contributions to DOC dynamics remain unclear, and without appropriate long-term monitoring data, it has not been possible to determine whether the ongoing “browning” is unprecedented or simply a “re-browning” to pre-industrial DOC levels. Here, we demonstrate the long-term impacts of acid deposition and climate change on lake-water DOC concentrations in low and high acid-deposition areas using infrared spectroscopic techniques on ~200-year-long lake-sediment records from central Canada. We show that acid deposition suppressed naturally higher DOC concentrations during the 20th century, but that a “re-browning” of lakes is now occurring with emissions reductions in formerly high deposition areas. In contrast, in low deposition areas, climate change is forcing lakes towards new ecological states, as lake-water DOC concentrations now often exceed pre-industrial levels.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of filtration methods and water volume on the quantification of brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) eDNA concentrations via droplet digital PCR.\n \n \n \n \n\n\n \n Capo, E.; Spong, G.; Königsson, H.; and Byström, P.\n\n\n \n\n\n\n Environmental DNA, 2(2): 152–160. November 2019.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/edn3.52\n\n\n\n
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\n\n\n@article{capo_effects_2019,\n\ttitle = {Effects of filtration methods and water volume on the quantification of brown trout ({Salmo} trutta) and {Arctic} char ({Salvelinus} alpinus) {eDNA} concentrations via droplet digital {PCR}},\n\tvolume = {2},\n\tissn = {2637-4943},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/edn3.52},\n\tdoi = {10.1002/edn3.52},\n\tabstract = {The quantification of the abundance of aquatic organisms via the use of environmental DNA (eDNA) molecules present in water is potentially a useful tool for efficient and noninvasive population monitoring. However, questions remain about the reliability of molecular methods. Among the factors that can hamper the reliability of the eDNA quantification, we investigated the influence of five filtration methods (filter pore size, filter type) and filtered water volume (1 and 2 L) on the total eDNA and the fish eDNA concentrations of two species, brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) from tanks with known number of individuals and biomass. We applied a droplet digital PCR (ddPCR) approach to DNA extracted from water samples collected from two cultivation tanks (each of them containing one of the targeted species). Results showed that the quantification of fish eDNA concentrations of both species varies with filtration methods. More specifically, the 0.45-µm Sterivex enclosed filters were identified to recover the highest eDNA concentrations. Difficulties to filter 2 L water samples were present for small pore size filters (≤0.45 µm) and likely caused by filter clogging. To overcome issues related to filter clogging, common in studies aiming to quantify fish eDNA molecules from water samples, we recommend a procedure involving filtration of multiple 1 L water samples with 0.45-µm enclosed filters, to recover both high quality and high concentrations of eDNA from targeted species, and subsequent processing of independent DNA extracts with the ddPCR method.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-03-19},\n\tjournal = {Environmental DNA},\n\tauthor = {Capo, Eric and Spong, Göran and Königsson, Helena and Byström, Pär},\n\tmonth = nov,\n\tyear = {2019},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/edn3.52},\n\tkeywords = {\\#nosource, Arctic char, brown trout, ddPCR assays, environmental DNA, lakes},\n\tpages = {152--160},\n}\n\n\n\n\n\n The quantification of the abundance of aquatic organisms via the use of environmental DNA (eDNA) molecules present in water is potentially a useful tool for efficient and noninvasive population monitoring. However, questions remain about the reliability of molecular methods. Among the factors that can hamper the reliability of the eDNA quantification, we investigated the influence of five filtration methods (filter pore size, filter type) and filtered water volume (1 and 2 L) on the total eDNA and the fish eDNA concentrations of two species, brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) from tanks with known number of individuals and biomass. We applied a droplet digital PCR (ddPCR) approach to DNA extracted from water samples collected from two cultivation tanks (each of them containing one of the targeted species). Results showed that the quantification of fish eDNA concentrations of both species varies with filtration methods. More specifically, the 0.45-µm Sterivex enclosed filters were identified to recover the highest eDNA concentrations. Difficulties to filter 2 L water samples were present for small pore size filters (≤0.45 µm) and likely caused by filter clogging. To overcome issues related to filter clogging, common in studies aiming to quantify fish eDNA molecules from water samples, we recommend a procedure involving filtration of multiple 1 L water samples with 0.45-µm enclosed filters, to recover both high quality and high concentrations of eDNA from targeted species, and subsequent processing of independent DNA extracts with the ddPCR method.\n
\n\n\n\n \n\n \n \n \n \n \n \n The unique methodological challenges of winter limnology.\n \n \n \n \n\n\n \n Block, B. D.; Denfeld, B. A.; Stockwell, J. D.; Flaim, G.; Grossart, H. F.; Knoll, L. B.; Maier, D. B.; North, R. L.; Rautio, M.; Rusak, J. A.; Sadro, S.; Weyhenmeyer, G. A.; Bramburger, A. J.; Branstrator, D. K.; Salonen, K.; and Hampton, S. E.\n\n\n \n\n\n\n Limnology and Oceanography: Methods, 17(1): 42–57. 2019.\n \n\n\n\n
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\n\n\n@article{block_unique_2019,\n\ttitle = {The unique methodological challenges of winter limnology},\n\tvolume = {17},\n\tcopyright = {© 2018 Association for the Sciences of Limnology and Oceanography},\n\tissn = {1541-5856},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lom3.10295},\n\tdoi = {10.1002/lom3.10295},\n\tabstract = {Winter is an important season for many limnological processes, which can range from biogeochemical transformations to ecological interactions. Interest in the structure and function of lake ecosystems under ice is on the rise. Although limnologists working at polar latitudes have a long history of winter work, the required knowledge to successfully sample under winter conditions is not widely available and relatively few limnologists receive formal training. In particular, the deployment and operation of equipment in below 0°C temperatures pose considerable logistical and methodological challenges, as do the safety risks of sampling during the ice-covered period. Here, we consolidate information on winter lake sampling and describe effective methods to measure physical, chemical, and biological variables in and under ice. We describe variation in snow and ice conditions and discuss implications for sampling logistics and safety. We outline commonly encountered methodological challenges and make recommendations for best practices to maximize safety and efficiency when sampling through ice or deploying instruments in ice-covered lakes. Application of such practices over a broad range of ice-covered lakes will contribute to a better understanding of the factors that regulate lakes during winter and how winter conditions affect the subsequent ice-free period.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2019-02-21},\n\tjournal = {Limnology and Oceanography: Methods},\n\tauthor = {Block, Benjamin D. and Denfeld, Blaize A. and Stockwell, Jason D. and Flaim, Giovanna and Grossart, Hans-Peter F. and Knoll, Lesley B. and Maier, Dominique B. and North, Rebecca L. and Rautio, Milla and Rusak, James A. and Sadro, Steve and Weyhenmeyer, Gesa A. and Bramburger, Andrew J. and Branstrator, Donn K. and Salonen, Kalevi and Hampton, Stephanie E.},\n\tyear = {2019},\n\tkeywords = {\\#nosource},\n\tpages = {42--57},\n}\n\n\n\n\n\n Winter is an important season for many limnological processes, which can range from biogeochemical transformations to ecological interactions. Interest in the structure and function of lake ecosystems under ice is on the rise. Although limnologists working at polar latitudes have a long history of winter work, the required knowledge to successfully sample under winter conditions is not widely available and relatively few limnologists receive formal training. In particular, the deployment and operation of equipment in below 0°C temperatures pose considerable logistical and methodological challenges, as do the safety risks of sampling during the ice-covered period. Here, we consolidate information on winter lake sampling and describe effective methods to measure physical, chemical, and biological variables in and under ice. We describe variation in snow and ice conditions and discuss implications for sampling logistics and safety. We outline commonly encountered methodological challenges and make recommendations for best practices to maximize safety and efficiency when sampling through ice or deploying instruments in ice-covered lakes. Application of such practices over a broad range of ice-covered lakes will contribute to a better understanding of the factors that regulate lakes during winter and how winter conditions affect the subsequent ice-free period.\n
\n\n\n\n \n\n \n \n \n \n \n \n Belowground plant parts are crucial for comprehensively estimating total plant richness in herbaceous and woody habitats.\n \n \n \n \n\n\n \n Träger, S.; Öpik, M.; Vasar, M.; and Wilson, S. D.\n\n\n \n\n\n\n Ecology, 100(2): e02575. 2019.\n \n\n\n\n
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\n\n\n@article{trager_belowground_2019,\n\ttitle = {Belowground plant parts are crucial for comprehensively estimating total plant richness in herbaceous and woody habitats},\n\tvolume = {100},\n\tcopyright = {© 2018 by the Ecological Society of America},\n\tissn = {1939-9170},\n\turl = {http://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.2575},\n\tdoi = {10.1002/ecy.2575},\n\tabstract = {Most studies consider aboveground plant species richness as a representative biodiversity measure. This approach inevitably assumes that the partitioning of total plant species richness into above- and belowground components is constant or at least consistent within and across vegetation types. However, with studies considering belowground plant richness still scarce and completely absent along vegetation gradients, this assumption lacks experimental support. Novel DNA sequencing techniques allow economical, high-throughput species identification of belowground environmental samples, enabling the measurement of the contributions of both above- and belowground plant components to total plant richness. We investigated above- and belowground plant species richness in four vegetation types (birch forest, heath, low alpine tundra, high alpine tundra) at the scale of herbaceous plant neighborhoods (dm) using 454 sequencing of the chloroplast trnL (UAA) intron to determine the plant species richness of environmental root samples and combined it with aboveground data from vegetation surveys to obtain total plant species richness. We correlated the measured plant species richness components with each other and with their respective plant biomass components within and across vegetation types. Total plant species richness exceeded aboveground richness twice on average and by as much as three times in low alpine tundra, indicating that a significant fraction of belowground plant richness cannot be recorded aboveground. More importantly, no consistent relationship among richness components (above- and belowground) was found within or across vegetation types, indicating that aboveground richness alone cannot predict total plant richness in contrasting vegetation types. Finally, no consistent relationship between plant richness and the corresponding biomass component was found. Our results clearly show that aboveground plant richness alone is a poor estimator of total plant species richness within and across different vegetation types. Consequently, it is crucial to account for belowground plant richness in future plant ecological studies in order to validate currently accepted plant richness patterns, as well as to measure potential changes in plant community composition in a changing environment.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2019-02-21},\n\tjournal = {Ecology},\n\tauthor = {Träger, Sabrina and Öpik, Maarja and Vasar, Martti and Wilson, Scott D.},\n\tyear = {2019},\n\tkeywords = {\\#nosource, 454 sequencing, above- and belowground plant richness, next-generation sequencing, plant biomass, root identification, trnL (UAA) intron, vegetation surveys},\n\tpages = {e02575},\n}\n\n\n\n\n\n Most studies consider aboveground plant species richness as a representative biodiversity measure. This approach inevitably assumes that the partitioning of total plant species richness into above- and belowground components is constant or at least consistent within and across vegetation types. However, with studies considering belowground plant richness still scarce and completely absent along vegetation gradients, this assumption lacks experimental support. Novel DNA sequencing techniques allow economical, high-throughput species identification of belowground environmental samples, enabling the measurement of the contributions of both above- and belowground plant components to total plant richness. We investigated above- and belowground plant species richness in four vegetation types (birch forest, heath, low alpine tundra, high alpine tundra) at the scale of herbaceous plant neighborhoods (dm) using 454 sequencing of the chloroplast trnL (UAA) intron to determine the plant species richness of environmental root samples and combined it with aboveground data from vegetation surveys to obtain total plant species richness. We correlated the measured plant species richness components with each other and with their respective plant biomass components within and across vegetation types. Total plant species richness exceeded aboveground richness twice on average and by as much as three times in low alpine tundra, indicating that a significant fraction of belowground plant richness cannot be recorded aboveground. More importantly, no consistent relationship among richness components (above- and belowground) was found within or across vegetation types, indicating that aboveground richness alone cannot predict total plant richness in contrasting vegetation types. Finally, no consistent relationship between plant richness and the corresponding biomass component was found. Our results clearly show that aboveground plant richness alone is a poor estimator of total plant species richness within and across different vegetation types. Consequently, it is crucial to account for belowground plant richness in future plant ecological studies in order to validate currently accepted plant richness patterns, as well as to measure potential changes in plant community composition in a changing environment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Investigating tissue bioconcentration and the behavioural effects of two pharmaceutical pollutants on sea trout (Salmo trutta) in the laboratory and field.\n \n \n \n \n\n\n \n McCallum, E. S.; Sundelin, A.; Fick, J.; Alanärä, A.; Klaminder, J.; Hellström, G.; and Brodin, T.\n\n\n \n\n\n\n Aquatic Toxicology, 207: 170–178. February 2019.\n \n\n\n\n
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\n\n\n@article{mccallum_investigating_2019,\n\ttitle = {Investigating tissue bioconcentration and the behavioural effects of two pharmaceutical pollutants on sea trout ({Salmo} trutta) in the laboratory and field},\n\tvolume = {207},\n\tissn = {0166-445X},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0166445X18307173},\n\tdoi = {10.1016/j.aquatox.2018.11.028},\n\tabstract = {Pharmaceuticals entering aquatic ecosystems via wastewater effluents are of increasing concern for wild animals. Because some pharmaceuticals are designed to modulate human behaviour, measuring the impacts of exposure to pharmaceuticals on fish behaviour has become a valuable endpoint. While laboratory studies have shown that pharmaceuticals can affect fish behaviour, there is a lack of understanding if behaviour is similarly affected in natural environments. Here, we exposed sea trout (Salmo trutta) smolts to two concentrations of two pharmaceutical pollutants often detected in surface waters: temazepam (a benzodiazepine, anxiolytic) or irbesartan (an angiotensin II receptor blocker, anti-hypertensive). We tested the hypothesis that changes to behavioural traits (anxiety and activity) measured in laboratory trials following exposure are predictive of behaviour in the natural environment (downstream migration). Measures of anxiety and activity in the laboratory assay did not vary with temazepam treatment, but temazepam-exposed fish began migrating faster in the field. Activity in the laboratory assay did predict overall migration speed in the field. In contrast to temazepam, we found that irbesartan exposure did not affect behaviour in the laboratory, field, or the relationship between the two endpoints. However, irbesartan was also not readily taken up into fish tissue (i.e. below detection levels in the muscle tissue), while temazepam bioconcentrated (bioconcentration factor 7.68) rapidly (t1/2 {\\textless} 24 h). Our findings add to a growing literature showing that benzodiazepine pollutants can modulate fish behaviour and that laboratory assays may be less sensitive at detecting the effects of pollutants compared to measuring effects in natural settings. Therefore, we underscore the importance of measuring behavioural effects in the natural environment.},\n\turldate = {2019-02-21},\n\tjournal = {Aquatic Toxicology},\n\tauthor = {McCallum, Erin S. and Sundelin, Anna and Fick, Jerker and Alanärä, Anders and Klaminder, Jonatan and Hellström, Gustav and Brodin, Tomas},\n\tmonth = feb,\n\tyear = {2019},\n\tkeywords = {\\#nosource, Bioconcentration, Ecotoxicology, In situ, Scototaxis, Steady-state},\n\tpages = {170--178},\n}\n\n\n\n\n\n Pharmaceuticals entering aquatic ecosystems via wastewater effluents are of increasing concern for wild animals. Because some pharmaceuticals are designed to modulate human behaviour, measuring the impacts of exposure to pharmaceuticals on fish behaviour has become a valuable endpoint. While laboratory studies have shown that pharmaceuticals can affect fish behaviour, there is a lack of understanding if behaviour is similarly affected in natural environments. Here, we exposed sea trout (Salmo trutta) smolts to two concentrations of two pharmaceutical pollutants often detected in surface waters: temazepam (a benzodiazepine, anxiolytic) or irbesartan (an angiotensin II receptor blocker, anti-hypertensive). We tested the hypothesis that changes to behavioural traits (anxiety and activity) measured in laboratory trials following exposure are predictive of behaviour in the natural environment (downstream migration). Measures of anxiety and activity in the laboratory assay did not vary with temazepam treatment, but temazepam-exposed fish began migrating faster in the field. Activity in the laboratory assay did predict overall migration speed in the field. In contrast to temazepam, we found that irbesartan exposure did not affect behaviour in the laboratory, field, or the relationship between the two endpoints. However, irbesartan was also not readily taken up into fish tissue (i.e. below detection levels in the muscle tissue), while temazepam bioconcentrated (bioconcentration factor 7.68) rapidly (t1/2 \\textless 24 h). Our findings add to a growing literature showing that benzodiazepine pollutants can modulate fish behaviour and that laboratory assays may be less sensitive at detecting the effects of pollutants compared to measuring effects in natural settings. Therefore, we underscore the importance of measuring behavioural effects in the natural environment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Ecological stoichiometry and nutrient partitioning in two insect herbivores responsible for large-scale forest disturbance in the Fennoscandian subarctic.\n \n \n \n \n\n\n \n Metcalfe, D. B.; Cherif, M.; Jepsen, J. U.; Vindstad, O. P. L.; Kristensen, J. Å; and Belsing, U.\n\n\n \n\n\n\n Ecological Entomology, 44: 118–128. 2019.\n \n\n\n\n
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\n\n\n@article{metcalfe_ecological_2019,\n\ttitle = {Ecological stoichiometry and nutrient partitioning in two insect herbivores responsible for large-scale forest disturbance in the {Fennoscandian} subarctic},\n\tvolume = {44},\n\tcopyright = {© 2018 The Royal Entomological Society},\n\tissn = {1365-2311},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/een.12679},\n\tdoi = {10.1111/een.12679},\n\tabstract = {1. Outbreaks of herbivorous insects can have large impacts on regional soil carbon (C) storage and nutrient cycling. In northernmost Europe, population outbreaks of several geometrid moth species regularly cause large-scale defoliation in subarctic birch forests. An improved understanding is required of how leaf C and nutrients are processed after ingestion by herbivores and what this means for the quantity and quality of different materials produced (frass, bodies). 2. In this study, larvae of two geometrid species responsible for major outbreaks (Epirrita autumnata and Operophtera brumata) were raised on exclusive diets of Betula pubescens var. czerepanovii (N. I. Orlova) Hämet Ahti and two other abundant understorey species (Betula nana, Vaccinium myrtillus). The quantities of C, nitrogen (N) and phosphorus (P) ingested and allocated to frass, bodies and (in the case of C) respired were recorded. 3. Overall, 23\\%, 70\\% and 48\\% of ingested C, N and P were allocated to bodies, respectively, rather than frass and (in the case of C) respiration. Operophtera brumata consistently maintained more constant body stoichiometric ratios of C, N and P than did E. autumnata, across the wide variation in physico-chemical properties of plant diet supplied. 4. These observed differences and similarities on C and nutrient processing may improve researchers' ability to predict the amount and stoichiometry of frass and bodies generated after geometrid outbreaks.},\n\tlanguage = {en},\n\turldate = {2018-10-25},\n\tjournal = {Ecological Entomology},\n\tauthor = {Metcalfe, Daniel B. and Cherif, Mehdi and Jepsen, Jane U. and Vindstad, Ole Petter L. and Kristensen, Jeppe Å and Belsing, Ulrika},\n\tyear = {2019},\n\tkeywords = {\\#nosource, Consumer-driven nutrient recycling, ecological stoichiometry, geometrid moth, homeostasis, stable isotope, subarctic birch forest},\n\tpages = {118--128},\n}\n\n\n\n\n\n 1. Outbreaks of herbivorous insects can have large impacts on regional soil carbon (C) storage and nutrient cycling. In northernmost Europe, population outbreaks of several geometrid moth species regularly cause large-scale defoliation in subarctic birch forests. An improved understanding is required of how leaf C and nutrients are processed after ingestion by herbivores and what this means for the quantity and quality of different materials produced (frass, bodies). 2. In this study, larvae of two geometrid species responsible for major outbreaks (Epirrita autumnata and Operophtera brumata) were raised on exclusive diets of Betula pubescens var. czerepanovii (N. I. Orlova) Hämet Ahti and two other abundant understorey species (Betula nana, Vaccinium myrtillus). The quantities of C, nitrogen (N) and phosphorus (P) ingested and allocated to frass, bodies and (in the case of C) respired were recorded. 3. Overall, 23%, 70% and 48% of ingested C, N and P were allocated to bodies, respectively, rather than frass and (in the case of C) respiration. Operophtera brumata consistently maintained more constant body stoichiometric ratios of C, N and P than did E. autumnata, across the wide variation in physico-chemical properties of plant diet supplied. 4. These observed differences and similarities on C and nutrient processing may improve researchers' ability to predict the amount and stoichiometry of frass and bodies generated after geometrid outbreaks.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting vegetation states do not diverge in soil organic matter storage: evidence from historical sites in tundra.\n \n \n \n \n\n\n \n Stark, S.; Egelkraut, D.; Aronsson, K.; and Olofsson, J.\n\n\n \n\n\n\n Ecology, 0(0): e02731. 2019.\n \n\n\n\n
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\n\n\n@article{stark_contrasting_2019,\n\ttitle = {Contrasting vegetation states do not diverge in soil organic matter storage: evidence from historical sites in tundra},\n\tvolume = {0},\n\tcopyright = {This article is protected by copyright. All rights reserved.},\n\tissn = {1939-9170},\n\tshorttitle = {Contrasting vegetation states do not diverge in soil organic matter storage},\n\turl = {http://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.2731},\n\tdoi = {10.1002/ecy.2731},\n\tabstract = {Ecosystems where severe disturbance has induced permanent shifts in vegetation and soil processes may represent alternative stable states. To date, little is known on how long-lasting changes in soil processes are following such disturbances, and how the changes in plant and soil processes between the alternative states eventually manifest themselves in soil organic matter (SOM) storage. Here, we analyzed plant density, the shrub:forb –ratio, microbial respiration, extracellular enzyme activities and SOM stocks in soils of subarctic tundra and historical milking grounds, where reindeer herding induced a vegetation transition from deciduous shrubs to graminoids several centuries earlier but were abandoned a century ago. This provides the possibility to compare sites with similar topography, but highly contrasting vegetation for centuries. We found that enzymatic activities and N:P stoichiometry differed between control and disturbed sites, confirming that culturally induced vegetation shifts exert lasting impacts on tundra soil processes. Transition zones, where shrubs had encroached into the historical milking grounds during the past 50 years, indicated that microbial activities for N and P acquisition changed more rapidly along a vegetation shift than those for microbial C acquisition. Although plant and soil processes differed between control and disturbed sites, we found no effect of historical vegetation transition on SOM stock. Across the study sites, soil SOM stocks were correlated with total plant density but not with the shrub:forb ratio. Our finding that SOM stock was insensitive to a centennial difference in plant community composition suggests that, as such, grazing-induced alternative vegetation states might not necessarily differ in SOM sequestration. This article is protected by copyright. All rights reserved.},\n\tlanguage = {en},\n\tnumber = {0},\n\turldate = {2019-04-23},\n\tjournal = {Ecology},\n\tauthor = {Stark, Sari and Egelkraut, Dagmar and Aronsson, Kjell-Åke and Olofsson, Johan},\n\tyear = {2019},\n\tkeywords = {\\#nosource, cultural landscape, extracellular enzymes, historical ecology, reindeer, soil carbon stock, tundra},\n\tpages = {e02731},\n}\n\n\n\n\n\n Ecosystems where severe disturbance has induced permanent shifts in vegetation and soil processes may represent alternative stable states. To date, little is known on how long-lasting changes in soil processes are following such disturbances, and how the changes in plant and soil processes between the alternative states eventually manifest themselves in soil organic matter (SOM) storage. Here, we analyzed plant density, the shrub:forb –ratio, microbial respiration, extracellular enzyme activities and SOM stocks in soils of subarctic tundra and historical milking grounds, where reindeer herding induced a vegetation transition from deciduous shrubs to graminoids several centuries earlier but were abandoned a century ago. This provides the possibility to compare sites with similar topography, but highly contrasting vegetation for centuries. We found that enzymatic activities and N:P stoichiometry differed between control and disturbed sites, confirming that culturally induced vegetation shifts exert lasting impacts on tundra soil processes. Transition zones, where shrubs had encroached into the historical milking grounds during the past 50 years, indicated that microbial activities for N and P acquisition changed more rapidly along a vegetation shift than those for microbial C acquisition. Although plant and soil processes differed between control and disturbed sites, we found no effect of historical vegetation transition on SOM stock. Across the study sites, soil SOM stocks were correlated with total plant density but not with the shrub:forb ratio. Our finding that SOM stock was insensitive to a centennial difference in plant community composition suggests that, as such, grazing-induced alternative vegetation states might not necessarily differ in SOM sequestration. This article is protected by copyright. All rights reserved.\n
\n\n\n\n \n\n \n \n \n \n \n \n Biogeochemistry of dissolved carbon, major and trace elements during spring flood periods on the Ob River.\n \n \n \n \n\n\n \n Vorobyev, S. N.; Pokrovsky, O. S.; Kolesnichenko, L. G.; Manasypov, R. M.; Shirokova, L. S.; Karlsson, J.; and Kirpotin, S. N.\n\n\n \n\n\n\n Hydrological Processes, 0(0): 0. 2019.\n \n\n\n\n
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\n\n\n@article{vorobyev_biogeochemistry_2019,\n\ttitle = {Biogeochemistry of dissolved carbon, major and trace elements during spring flood periods on the {Ob} {River}},\n\tvolume = {0},\n\tcopyright = {This article is protected by copyright. All rights reserved.},\n\tissn = {1099-1085},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.13424},\n\tdoi = {10.1002/hyp.13424},\n\tabstract = {Detailed knowledge of the flood period of Arctic rivers remains one of the few factors impeding rigorous prediction of the effect of climate change on carbon and related element flux from the land to the Arctic Ocean. In order to test the temporal and spatial variability of element concentration in the Ob River (western Siberia) water during flood period, and to quantify the contribution of spring flood period to the annual element export, we sampled the main channel year round in 2014-2017 for dissolved C, major and trace element concentrations. We revealed high stability (ca ≤ 10\\% relative variation) of dissolved C, major and trace element concentrations in the Ob River during spring flood period over a 1 km section of the river channel and over 3 days continuous monitoring (3 h frequency). We identified two groups of elements with contrasting relationship to discharge: (1) DIC and soluble elements (Cl, SO4, Li, B, Na, Mg, Ca, P, V, Cr, Mn, As, Rb, Sr, Mo, Ba, W, U) negatively correlated (p {\\textless} 0.05) with discharge and exhibited minimal concentrations during spring flood and autumn high flow, and (2) DOC and particle-reactive elements (Al, Fe, Ti, Y, Zr, Nb, Cs, REEs, Hf, Tl, Pb, Th), some nutrients (K) and metalloids (Ge, Sb, Te), positively correlated (p {\\textless} 0.05) with discharge and showed highest concentrations during spring flood. We attribute the decreased concentration of soluble elements with discharge to dilution by groundwater feeding, and increased concentration of DOC and particle-reactive metals with discharge to leaching from surface soil, plant litter and suspended particles. Overall, the present study provides first order assessment of fluxes of major and trace elements in the middle course of the Ob River and reveals their high temporal and spatial stability as well as characterizes the mechanism of river water chemical composition acquisition.},\n\tlanguage = {en},\n\tnumber = {0},\n\turldate = {2019-03-22},\n\tjournal = {Hydrological Processes},\n\tauthor = {Vorobyev, S. N. and Pokrovsky, O. S. and Kolesnichenko, L. G. and Manasypov, R. M. and Shirokova, L. S. and Karlsson, J. and Kirpotin, S. N.},\n\tyear = {2019},\n\tkeywords = {\\#nosource, Siberia, baseflow, colloids, flood, lakes, metals, organic carbon, riparian zone, rivers, underground waters},\n\tpages = {0},\n}\n\n\n\n\n\n Detailed knowledge of the flood period of Arctic rivers remains one of the few factors impeding rigorous prediction of the effect of climate change on carbon and related element flux from the land to the Arctic Ocean. In order to test the temporal and spatial variability of element concentration in the Ob River (western Siberia) water during flood period, and to quantify the contribution of spring flood period to the annual element export, we sampled the main channel year round in 2014-2017 for dissolved C, major and trace element concentrations. We revealed high stability (ca ≤ 10% relative variation) of dissolved C, major and trace element concentrations in the Ob River during spring flood period over a 1 km section of the river channel and over 3 days continuous monitoring (3 h frequency). We identified two groups of elements with contrasting relationship to discharge: (1) DIC and soluble elements (Cl, SO4, Li, B, Na, Mg, Ca, P, V, Cr, Mn, As, Rb, Sr, Mo, Ba, W, U) negatively correlated (p \\textless 0.05) with discharge and exhibited minimal concentrations during spring flood and autumn high flow, and (2) DOC and particle-reactive elements (Al, Fe, Ti, Y, Zr, Nb, Cs, REEs, Hf, Tl, Pb, Th), some nutrients (K) and metalloids (Ge, Sb, Te), positively correlated (p \\textless 0.05) with discharge and showed highest concentrations during spring flood. We attribute the decreased concentration of soluble elements with discharge to dilution by groundwater feeding, and increased concentration of DOC and particle-reactive metals with discharge to leaching from surface soil, plant litter and suspended particles. Overall, the present study provides first order assessment of fluxes of major and trace elements in the middle course of the Ob River and reveals their high temporal and spatial stability as well as characterizes the mechanism of river water chemical composition acquisition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Alternative transient states and slow plant community responses after changed flooding regimes.\n \n \n \n \n\n\n \n Sarneel, J. M.; Hefting, M. M.; Kowalchuk, G. A.; Nilsson, C.; Velden, M. V. d.; Visser, E. J. W.; Voesenek, L. A. C. J.; and Jansson, R.\n\n\n \n\n\n\n Global Change Biology, 25(4): 1358–1367. 2019.\n \n\n\n\n
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\n\n\n@article{sarneel_alternative_2019,\n\ttitle = {Alternative transient states and slow plant community responses after changed flooding regimes},\n\tvolume = {25},\n\tcopyright = {© 2019 The Authors. Global Change Biology Published by John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14569},\n\tdoi = {10.1111/gcb.14569},\n\tabstract = {Climate change will have large consequences for flooding frequencies in freshwater systems. In interaction with anthropogenic activities (flow regulation, channel restoration and catchment land-use) this will both increase flooding and drought across the world. Like in many other ecosystems facing changed environmental conditions, it remains difficult to predict the rate and trajectory of vegetation responses to changed conditions. Given that critical ecosystem services (e.g. bank stabilization, carbon subsidies to aquatic communities or water purification) depend on riparian vegetation composition, it is important to understand how and how fast riparian vegetation responds to changing flooding regimes. We studied vegetation changes over 19 growing seasons in turfs that were transplanted in a full-factorial design between three riparian elevations with different flooding frequencies. We found that (a) some transplanted communities may have developed into an alternative stable state and were still different from the target community, and (b) pathways of vegetation change were highly directional but alternative trajectories did occur, (c) changes were rather linear but faster when flooding frequencies increased than when they decreased, and (d) we observed fastest changes in turfs when proxies for mortality and colonization were highest. These results provide rare examples of alternative transient trajectories and stable states under field conditions, which is an important step towards understanding their drivers and their frequency in a changing world.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2019-04-05},\n\tjournal = {Global Change Biology},\n\tauthor = {Sarneel, Judith M. and Hefting, Mariet M. and Kowalchuk, George A. and Nilsson, Christer and Velden, Merit Van der and Visser, Eric J. W. and Voesenek, Laurentius A. C. J. and Jansson, Roland},\n\tyear = {2019},\n\tkeywords = {\\#nosource, alternative stable states, drought events, flood regime change, hydrological alterations, hysteresis, riparian vegetation, river restoration, species traits},\n\tpages = {1358--1367},\n}\n\n\n\n\n\n Climate change will have large consequences for flooding frequencies in freshwater systems. In interaction with anthropogenic activities (flow regulation, channel restoration and catchment land-use) this will both increase flooding and drought across the world. Like in many other ecosystems facing changed environmental conditions, it remains difficult to predict the rate and trajectory of vegetation responses to changed conditions. Given that critical ecosystem services (e.g. bank stabilization, carbon subsidies to aquatic communities or water purification) depend on riparian vegetation composition, it is important to understand how and how fast riparian vegetation responds to changing flooding regimes. We studied vegetation changes over 19 growing seasons in turfs that were transplanted in a full-factorial design between three riparian elevations with different flooding frequencies. We found that (a) some transplanted communities may have developed into an alternative stable state and were still different from the target community, and (b) pathways of vegetation change were highly directional but alternative trajectories did occur, (c) changes were rather linear but faster when flooding frequencies increased than when they decreased, and (d) we observed fastest changes in turfs when proxies for mortality and colonization were highest. These results provide rare examples of alternative transient trajectories and stable states under field conditions, which is an important step towards understanding their drivers and their frequency in a changing world.\n
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\n \n \n\n \n \n \n \n \n \n Consequences of grazer-induced vegetation transitions on ecosystem carbon storage in the tundra.\n \n \n \n \n\n\n \n Ylänne, H.; Olofsson, J.; Oksanen, L.; and Stark, S.\n\n\n \n\n\n\n Functional Ecology, 32(4): 1091–1102. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.13029\n\n\n\n
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\n\n\n@article{ylanne_consequences_2018,\n\ttitle = {Consequences of grazer-induced vegetation transitions on ecosystem carbon storage in the tundra},\n\tvolume = {32},\n\tcopyright = {© 2017 The Authors. Functional Ecology © 2017 British Ecological Society},\n\tissn = {1365-2435},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.13029},\n\tdoi = {10.1111/1365-2435.13029},\n\tabstract = {Large herbivores can control plant community composition and, under certain conditions, even induce vegetation shifts to alternative ecosystem states. As different plant assemblages maintain contrasting carbon (C) cycling patterns, herbivores have the potential to alter C sequestration at regional scales. Their influence is of particular interest in the Arctic tundra, where a large share of the world's soil C reservoir is stored. We assessed the influence of grazing mammals on tundra vegetation and C stocks by resampling two sites located along pasture rotation fences in northern Norway. These fences have separated lightly grazed areas from heavily grazed areas (in close proximity to the fences) and moderately grazed areas (further away from the fences) for the past 50 years. Fourteen years earlier, the lightly and moderately grazed areas were dominated by dwarf shrubs, whereas heavy grazing had promoted the establishment of graminoid-dominated vegetation. Since then, both reindeer densities and temperatures have increased, and more time has passed for transient dynamics to be expressed. We expected that the vegetation and C stocks would have changed under all grazing intensities, but not necessarily in the same way. At the site where relative reindeer numbers and trampling intensity had increased the most, graminoid-dominated vegetation was now also found in the moderately grazed area. At the other site, the dominant vegetation types under all grazing intensities were the same as 14 years earlier. We show that the heavily grazed, graminoid-dominated areas stored less C above-ground than the lightly grazed, shrub-dominated areas. Yet, the below-ground consequences of grazing-induced grassification varied between the sites: Grazing did not alter organic soil C stocks at the site where both evergreen and deciduous shrubs were abundant in the lightly grazed area, whereas heavy grazing increased organic soil C stocks at the site where the deciduous shrub Betula nana was dominant. Our results indicate that, despite the negative impacts of grazers on above-ground C storage, their impact on below-ground C may even be positive. We suggest that the site-specific responses of organic soil C stocks to grazing could be explained by the differences in vegetation under light grazing. This would imply that the replacement of deciduous shrubs by graminoids, as a consequence of grazing could be beneficial for C sequestration in tundra soils. A plain language summary is available for this article.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Functional Ecology},\n\tauthor = {Ylänne, Henni and Olofsson, Johan and Oksanen, Lauri and Stark, Sari},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.13029},\n\tkeywords = {\\#nosource, Carbon stocks, Grazing, Herbivory, Plant functional types, Plant–soil interactions, Rangifer tarandus, Reindeer, Soil carbon, carbon stocks, grazing, herbivory, plant functional types, plant–soil interactions, reindeer, soil carbon},\n\tpages = {1091--1102},\n}\n\n\n\n\n\n Large herbivores can control plant community composition and, under certain conditions, even induce vegetation shifts to alternative ecosystem states. As different plant assemblages maintain contrasting carbon (C) cycling patterns, herbivores have the potential to alter C sequestration at regional scales. Their influence is of particular interest in the Arctic tundra, where a large share of the world's soil C reservoir is stored. We assessed the influence of grazing mammals on tundra vegetation and C stocks by resampling two sites located along pasture rotation fences in northern Norway. These fences have separated lightly grazed areas from heavily grazed areas (in close proximity to the fences) and moderately grazed areas (further away from the fences) for the past 50 years. Fourteen years earlier, the lightly and moderately grazed areas were dominated by dwarf shrubs, whereas heavy grazing had promoted the establishment of graminoid-dominated vegetation. Since then, both reindeer densities and temperatures have increased, and more time has passed for transient dynamics to be expressed. We expected that the vegetation and C stocks would have changed under all grazing intensities, but not necessarily in the same way. At the site where relative reindeer numbers and trampling intensity had increased the most, graminoid-dominated vegetation was now also found in the moderately grazed area. At the other site, the dominant vegetation types under all grazing intensities were the same as 14 years earlier. We show that the heavily grazed, graminoid-dominated areas stored less C above-ground than the lightly grazed, shrub-dominated areas. Yet, the below-ground consequences of grazing-induced grassification varied between the sites: Grazing did not alter organic soil C stocks at the site where both evergreen and deciduous shrubs were abundant in the lightly grazed area, whereas heavy grazing increased organic soil C stocks at the site where the deciduous shrub Betula nana was dominant. Our results indicate that, despite the negative impacts of grazers on above-ground C storage, their impact on below-ground C may even be positive. We suggest that the site-specific responses of organic soil C stocks to grazing could be explained by the differences in vegetation under light grazing. This would imply that the replacement of deciduous shrubs by graminoids, as a consequence of grazing could be beneficial for C sequestration in tundra soils. A plain language summary is available for this article.\n
\n\n\n\n \n\n \n \n \n \n \n \n Human-mediated introduction of geoengineering earthworms in the Fennoscandian arctic.\n \n \n \n \n\n\n \n Wackett, A. A.; Yoo, K.; Olofsson, J.; and Klaminder, J.\n\n\n \n\n\n\n Biological Invasions, 20(6): 1377–1386. June 2018.\n \n\n\n\n
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\n\n\n@article{wackett_human-mediated_2018,\n\ttitle = {Human-mediated introduction of geoengineering earthworms in the {Fennoscandian} arctic},\n\tvolume = {20},\n\tissn = {1573-1464},\n\turl = {https://doi.org/10.1007/s10530-017-1642-7},\n\tdoi = {10.1007/s10530-017-1642-7},\n\tabstract = {It is now well established that European earthworms are re-shaping formerly glaciated forests in North America with dramatic ecological consequences. However, few have considered the potential invasiveness of this species assemblage in the European arctic. Here we argue that some earthworm species (Lumbricus rubellus, Lumbricus terrestris and Aporrectodea sp.) with great geomorphological impact (geoengineering species) are non-native and invasive in the Fennoscandian arctic birch forests, where they have been introduced by agrarian settlers and most recently through recreational fishing and gardening. Our exploratory surveys indicate no obvious historical dispersal mechanism that can explain early arrival of these earthworms into the Fennoscandian arctic: that is, these species do not appear to establish naturally along coastlines mimicking conditions following deglaciation in Fennoscandia, nor were they spread by early native (Sami) cultures. The importance of anthropogenic sources and the invasive characteristics of L. rubellus and Aporrectodea sp. in the arctic is evident from their radiation outwards from abandoned farms and modern cabin lawns into adjacent arctic birch forests. They appear to outcompete previously established litter-dwelling earthworm species (i.e. Dendrobaena octaedra) that likely colonized the Fennoscandian landscape rapidly following deglaciation via hydrochory and/or dispersal by early Sami settlements. The high geoengineering earthworm biomasses, their recognized ecological impact in other formerly glaciated environments, and their persistence once established leads us to suggest that geoengineering earthworms may pose a potent threat to some of the most remote and protected arctic environments in northern Europe.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Biological Invasions},\n\tauthor = {Wackett, Adrian A. and Yoo, Kyungsoo and Olofsson, Johan and Klaminder, Jonatan},\n\tmonth = jun,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Arctic, Earthworm invasion, Hydrochory, Land use, Lumbricidae},\n\tpages = {1377--1386},\n}\n\n\n\n\n\n It is now well established that European earthworms are re-shaping formerly glaciated forests in North America with dramatic ecological consequences. However, few have considered the potential invasiveness of this species assemblage in the European arctic. Here we argue that some earthworm species (Lumbricus rubellus, Lumbricus terrestris and Aporrectodea sp.) with great geomorphological impact (geoengineering species) are non-native and invasive in the Fennoscandian arctic birch forests, where they have been introduced by agrarian settlers and most recently through recreational fishing and gardening. Our exploratory surveys indicate no obvious historical dispersal mechanism that can explain early arrival of these earthworms into the Fennoscandian arctic: that is, these species do not appear to establish naturally along coastlines mimicking conditions following deglaciation in Fennoscandia, nor were they spread by early native (Sami) cultures. The importance of anthropogenic sources and the invasive characteristics of L. rubellus and Aporrectodea sp. in the arctic is evident from their radiation outwards from abandoned farms and modern cabin lawns into adjacent arctic birch forests. They appear to outcompete previously established litter-dwelling earthworm species (i.e. Dendrobaena octaedra) that likely colonized the Fennoscandian landscape rapidly following deglaciation via hydrochory and/or dispersal by early Sami settlements. The high geoengineering earthworm biomasses, their recognized ecological impact in other formerly glaciated environments, and their persistence once established leads us to suggest that geoengineering earthworms may pose a potent threat to some of the most remote and protected arctic environments in northern Europe.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of Terrestrial Organic Matter on Aquatic Primary Production as Mediated by Pelagic–Benthic Resource Fluxes.\n \n \n \n \n\n\n \n Rivera Vasconcelos, F.; Diehl, S.; Rodríguez, P.; Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Ecosystems, 21(6): 1255–1268. September 2018.\n \n\n\n\n
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\n\n\n@article{rivera_vasconcelos_effects_2018,\n\ttitle = {Effects of {Terrestrial} {Organic} {Matter} on {Aquatic} {Primary} {Production} as {Mediated} by {Pelagic}–{Benthic} {Resource} {Fluxes}},\n\tvolume = {21},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-017-0217-x},\n\tdoi = {10.1007/s10021-017-0217-x},\n\tabstract = {Flows of energy and matter across habitat boundaries can be major determinants of the functioning of recipient ecosystems. It is currently debated whether terrestrial dissolved organic matter (tDOM) is a resource subsidy or a resource subtraction in recipient lakes. We present data from a long-term field experiment in which pelagic phosphorus concentration and whole-ecosystem primary production increased with increasing tDOM input, suggesting that tDOM acted primarily as a direct nutrient subsidy. Piecewise structural equation modeling supports, however, a substantial contribution of a second mechanism: colored tDOM acted also as a resource subtraction by shading benthic algae, preventing them from intercepting nutrients released across the sediment–water interface. Inhibition of benthic algae by colored tDOM thus indirectly promoted pelagic algae and whole-ecosystem primary production. We conclude that cross-ecosystem terrestrial DOM inputs can modify light and nutrient flows between aquatic habitats and alter the relative contributions of benthic and pelagic habitats to total primary production. These results are particularly relevant for shallow northern lakes, which are projected to receive increased tDOM runoff.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Rivera Vasconcelos, Francisco and Diehl, Sebastian and Rodríguez, Patricia and Karlsson, Jan and Byström, Pär},\n\tmonth = sep,\n\tyear = {2018},\n\tkeywords = {\\#nosource, allochthonous input, benthic, brownification, dissolved organic matter, light, nutrients, pelagic, piecewise SEM, resource competition, spatial subsidy, warming},\n\tpages = {1255--1268},\n}\n\n\n\n\n\n Flows of energy and matter across habitat boundaries can be major determinants of the functioning of recipient ecosystems. It is currently debated whether terrestrial dissolved organic matter (tDOM) is a resource subsidy or a resource subtraction in recipient lakes. We present data from a long-term field experiment in which pelagic phosphorus concentration and whole-ecosystem primary production increased with increasing tDOM input, suggesting that tDOM acted primarily as a direct nutrient subsidy. Piecewise structural equation modeling supports, however, a substantial contribution of a second mechanism: colored tDOM acted also as a resource subtraction by shading benthic algae, preventing them from intercepting nutrients released across the sediment–water interface. Inhibition of benthic algae by colored tDOM thus indirectly promoted pelagic algae and whole-ecosystem primary production. We conclude that cross-ecosystem terrestrial DOM inputs can modify light and nutrient flows between aquatic habitats and alter the relative contributions of benthic and pelagic habitats to total primary production. These results are particularly relevant for shallow northern lakes, which are projected to receive increased tDOM runoff.\n
\n\n\n\n \n\n \n \n \n \n \n \n Headwater Mires Constitute a Major Source of Nitrogen (N) to Surface Waters in the Boreal Landscape.\n \n \n \n \n\n\n \n Sponseller, R. A.; Blackburn, M.; Nilsson, M. B.; and Laudon, H.\n\n\n \n\n\n\n Ecosystems, 21(1): 31–44. January 2018.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{sponseller_headwater_2018,\n\ttitle = {Headwater {Mires} {Constitute} a {Major} {Source} of {Nitrogen} ({N}) to {Surface} {Waters} in the {Boreal} {Landscape}},\n\tvolume = {21},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-017-0133-0},\n\tdoi = {10.1007/s10021-017-0133-0},\n\tabstract = {Nutrient exports from soils have important implications for long-term patterns of nutrient limitation on land and resource delivery to aquatic environments. While plant–soil systems are notably efficient at retaining limiting nutrients, spatial and temporal mismatches in resource supply and demand may create opportunities for hydrologic losses to occur. Spatial mismatches may be particularly important in peat-forming landscapes, where the development of a two-layer vertical structure can isolate plant communities on the surface from resource pools that accumulate at depth. Our objectives were to test this idea in northern Sweden, where nitrogen (N) limitation of terrestrial plants is widespread, and where peat-forming, mire ecosystems are dominant features of the landscape. We quantified vertical patterns of N chemistry in a minerogenic mire, estimated the seasonal and annual hydrologic export of organic and inorganic N from this system, and evaluated the broader influence of mire cover on N chemistry across a stream network. Relatively high concentrations of ammonium (up to 2 mg l−1) were observed in groundwater several meters below the peat surface, and N was routed to the outlet stream along deep, preferential flowpaths. Areal estimates of inorganic N export from the mire were several times greater than from an adjacent, forested catchment, with markedly higher loss rates during the growing season, when plant N demand is ostensibly greatest. At broader scales, mire cover was positively correlated with long-term concentrations of inorganic and organic N in streams across the drainage network. This study provides an example of how mire formation and peat accumulation can create broad-scale heterogeneity in nutrient supply and demand across boreal landscapes. This mismatch allows for hydrologic losses of reactive N that are independent of annual plant demand and potentially important to receiving lakes and streams.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Sponseller, Ryan A. and Blackburn, M. and Nilsson, M. B. and Laudon, H.},\n\tmonth = jan,\n\tyear = {2018},\n\tkeywords = {\\#nosource, boreal, mire, nitrogen, peat, peatlands, watershed biogeochemistry},\n\tpages = {31--44},\n}\n\n\n\n\n\n Nutrient exports from soils have important implications for long-term patterns of nutrient limitation on land and resource delivery to aquatic environments. While plant–soil systems are notably efficient at retaining limiting nutrients, spatial and temporal mismatches in resource supply and demand may create opportunities for hydrologic losses to occur. Spatial mismatches may be particularly important in peat-forming landscapes, where the development of a two-layer vertical structure can isolate plant communities on the surface from resource pools that accumulate at depth. Our objectives were to test this idea in northern Sweden, where nitrogen (N) limitation of terrestrial plants is widespread, and where peat-forming, mire ecosystems are dominant features of the landscape. We quantified vertical patterns of N chemistry in a minerogenic mire, estimated the seasonal and annual hydrologic export of organic and inorganic N from this system, and evaluated the broader influence of mire cover on N chemistry across a stream network. Relatively high concentrations of ammonium (up to 2 mg l−1) were observed in groundwater several meters below the peat surface, and N was routed to the outlet stream along deep, preferential flowpaths. Areal estimates of inorganic N export from the mire were several times greater than from an adjacent, forested catchment, with markedly higher loss rates during the growing season, when plant N demand is ostensibly greatest. At broader scales, mire cover was positively correlated with long-term concentrations of inorganic and organic N in streams across the drainage network. This study provides an example of how mire formation and peat accumulation can create broad-scale heterogeneity in nutrient supply and demand across boreal landscapes. This mismatch allows for hydrologic losses of reactive N that are independent of annual plant demand and potentially important to receiving lakes and streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n High riverine CO2 emissions at the permafrost boundary of Western Siberia.\n \n \n \n \n\n\n \n Serikova, S.; Pokrovsky, O. S.; Ala-Aho, P.; Kazantsev, V.; Kirpotin, S. N.; Kopysov, S. G.; Krickov, I. V.; Laudon, H.; Manasypov, R. M.; Shirokova, L. S.; Soulsby, C.; Tetzlaff, D.; and Karlsson, J.\n\n\n \n\n\n\n Nature Geoscience, 11(11): 825–829. November 2018.\n Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{serikova_high_2018,\n\ttitle = {High riverine {CO2} emissions at the permafrost boundary of {Western} {Siberia}},\n\tvolume = {11},\n\tcopyright = {2018 The Author(s)},\n\tissn = {1752-0908},\n\turl = {https://www.nature.com/articles/s41561-018-0218-1},\n\tdoi = {10.1038/s41561-018-0218-1},\n\tabstract = {The fate of the vast stocks of organic carbon stored in permafrost of the Western Siberian Lowland, the world’s largest peatland, is uncertain. Specifically, the amount of greenhouse gas emissions from rivers in the region is unknown. Here we present estimates of annual CO2 emissions from 58 rivers across all permafrost zones of the Western Siberian Lowland, between 56 and 67° N. We find that emissions peak at the permafrost boundary, and decrease where permafrost is more prevalent and in colder climatic conditions. River CO2 emissions were high, and on average two times greater than downstream carbon export. We suggest that high emissions and emission/export ratios are a result of warm temperatures and the long transit times of river water. We show that rivers in the Western Siberian Lowland play an important role in the carbon cycle by degassing terrestrial carbon before its transport to the Arctic Ocean, and suggest that changes in both temperature and precipitation are important for understanding and predicting high-latitude river CO2 emissions in a changing climate.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2024-03-27},\n\tjournal = {Nature Geoscience},\n\tauthor = {Serikova, S. and Pokrovsky, O. S. and Ala-Aho, P. and Kazantsev, V. and Kirpotin, S. N. and Kopysov, S. G. and Krickov, I. V. and Laudon, H. and Manasypov, R. M. and Shirokova, L. S. and Soulsby, C. and Tetzlaff, D. and Karlsson, J.},\n\tmonth = nov,\n\tyear = {2018},\n\tnote = {Publisher: Nature Publishing Group},\n\tkeywords = {\\#nosource, Carbon cycle, Climate-change impacts, Limnology},\n\tpages = {825--829},\n}\n\n\n\n\n\n The fate of the vast stocks of organic carbon stored in permafrost of the Western Siberian Lowland, the world’s largest peatland, is uncertain. Specifically, the amount of greenhouse gas emissions from rivers in the region is unknown. Here we present estimates of annual CO2 emissions from 58 rivers across all permafrost zones of the Western Siberian Lowland, between 56 and 67° N. We find that emissions peak at the permafrost boundary, and decrease where permafrost is more prevalent and in colder climatic conditions. River CO2 emissions were high, and on average two times greater than downstream carbon export. We suggest that high emissions and emission/export ratios are a result of warm temperatures and the long transit times of river water. We show that rivers in the Western Siberian Lowland play an important role in the carbon cycle by degassing terrestrial carbon before its transport to the Arctic Ocean, and suggest that changes in both temperature and precipitation are important for understanding and predicting high-latitude river CO2 emissions in a changing climate.\n
\n\n\n\n \n\n \n \n \n \n \n \n Autumnal warming does not change root phenology in two contrasting vegetation types of subarctic tundra.\n \n \n \n \n\n\n \n Schwieger, S.; Kreyling, J.; Milbau, A.; and Blume-Werry, G.\n\n\n \n\n\n\n Plant and Soil, 424(1): 145–156. March 2018.\n \n\n\n\n
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\n\n\n@article{schwieger_autumnal_2018,\n\ttitle = {Autumnal warming does not change root phenology in two contrasting vegetation types of subarctic tundra},\n\tvolume = {424},\n\tissn = {1573-5036},\n\turl = {https://doi.org/10.1007/s11104-017-3343-5},\n\tdoi = {10.1007/s11104-017-3343-5},\n\tabstract = {Root phenology is important in controlling carbon and nutrient fluxes in terrestrial ecosystems, yet, remains largely unexplored, especially in the Arctic. We compared below- and aboveground phenology and ending of the growing season in two contrasting vegetation types of subarctic tundra: heath and meadow, and their response to experimental warming in autumn.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Plant and Soil},\n\tauthor = {Schwieger, Sarah and Kreyling, Jürgen and Milbau, Ann and Blume-Werry, Gesche},\n\tmonth = mar,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Belowground, Climate change, Fine roots, Plant phenology, Root growth, Subarctic tundra},\n\tpages = {145--156},\n}\n\n\n\n\n\n Root phenology is important in controlling carbon and nutrient fluxes in terrestrial ecosystems, yet, remains largely unexplored, especially in the Arctic. We compared below- and aboveground phenology and ending of the growing season in two contrasting vegetation types of subarctic tundra: heath and meadow, and their response to experimental warming in autumn.\n
\n\n\n\n \n\n \n \n \n \n \n \n Freeze-thaw cycles of Arctic thaw ponds remove colloidal metals and generate low-molecular-weight organic matter.\n \n \n \n \n\n\n \n Pokrovsky, O. S.; Karlsson, J.; and Giesler, R.\n\n\n \n\n\n\n Biogeochemistry, 137(3): 321–336. February 2018.\n \n\n\n\n
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\n\n\n@article{pokrovsky_freeze-thaw_2018,\n\ttitle = {Freeze-thaw cycles of {Arctic} thaw ponds remove colloidal metals and generate low-molecular-weight organic matter},\n\tvolume = {137},\n\tissn = {1573-515X},\n\turl = {https://doi.org/10.1007/s10533-018-0421-6},\n\tdoi = {10.1007/s10533-018-0421-6},\n\tabstract = {High-latitude boreal and arctic surface/inland waters contain sizeable reservoirs of dissolved organic matter (DOM) and trace elements (TE), which are subject to seasonal freezing. Specifically, shallow ponds and lakes in the permafrost zone often freeze solid, which can lead to transformations in the colloidal and dissolved fractions of DOM and TE. Here, we present results from experimental freeze-thaw cycles using iron (Fe)- and DOM-rich water from thaw ponds situated in Stordalen and Storflaket palsa mires in northern Sweden. After ten cycles of freezing, 85\\% of Fe and 25\\% of dissolved organic carbon (DOC) were removed from solution in circumneutral fen water (pH 6.9) but a much smaller removal of Fe and DOC ({\\textless} 7\\%) was found in acidic bog water (pH 3.6). This removal pattern was consistent with initial supersaturation of fen water with respect to Fe hydroxide and a lack of supersaturation with any secondary mineral phase in the bog water. There was a nearly two- to threefold increase in the low-molecular-weight (LMW) fraction of organic carbon (OC) and several TEs caused by the repeated freeze-thaw cycles. Future increases in the freeze-thaw frequency of surface waters with climate warming may remove up to 25\\% of DOC in circumneutral organic-rich waters. Furthermore, an increase of LMW OC may result in enhanced carbon dioxide losses from aquatic ecosystems since this fraction is potentially more susceptible to biodegradation.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Biogeochemistry},\n\tauthor = {Pokrovsky, Oleg S. and Karlsson, Jan and Giesler, Reiner},\n\tmonth = feb,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Bog, Carbon, Fen, Metal, Peat, Ultrafiltration, stordalen, storflaket},\n\tpages = {321--336},\n}\n\n\n\n\n\n High-latitude boreal and arctic surface/inland waters contain sizeable reservoirs of dissolved organic matter (DOM) and trace elements (TE), which are subject to seasonal freezing. Specifically, shallow ponds and lakes in the permafrost zone often freeze solid, which can lead to transformations in the colloidal and dissolved fractions of DOM and TE. Here, we present results from experimental freeze-thaw cycles using iron (Fe)- and DOM-rich water from thaw ponds situated in Stordalen and Storflaket palsa mires in northern Sweden. After ten cycles of freezing, 85% of Fe and 25% of dissolved organic carbon (DOC) were removed from solution in circumneutral fen water (pH 6.9) but a much smaller removal of Fe and DOC (\\textless 7%) was found in acidic bog water (pH 3.6). This removal pattern was consistent with initial supersaturation of fen water with respect to Fe hydroxide and a lack of supersaturation with any secondary mineral phase in the bog water. There was a nearly two- to threefold increase in the low-molecular-weight (LMW) fraction of organic carbon (OC) and several TEs caused by the repeated freeze-thaw cycles. Future increases in the freeze-thaw frequency of surface waters with climate warming may remove up to 25% of DOC in circumneutral organic-rich waters. Furthermore, an increase of LMW OC may result in enhanced carbon dioxide losses from aquatic ecosystems since this fraction is potentially more susceptible to biodegradation.\n
\n\n\n\n \n\n \n \n \n \n \n \n Persistent nitrogen limitation of stream biofilm communities along climate gradients in the Arctic.\n \n \n \n \n\n\n \n Myrstener, M.; Rocher-Ros, G.; Burrows, R. M.; Bergström, A.; Giesler, R.; and Sponseller, R. A.\n\n\n \n\n\n\n Global Change Biology, 24(8): 3680–3691. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14117\n\n\n\n
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\n\n\n@article{myrstener_persistent_2018,\n\ttitle = {Persistent nitrogen limitation of stream biofilm communities along climate gradients in the {Arctic}},\n\tvolume = {24},\n\tcopyright = {© 2018 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14117},\n\tdoi = {10.1111/gcb.14117},\n\tabstract = {Climate change is rapidly reshaping Arctic landscapes through shifts in vegetation cover and productivity, soil resource mobilization, and hydrological regimes. The implications of these changes for stream ecosystems and food webs is unclear and will depend largely on microbial biofilm responses to concurrent shifts in temperature, light, and resource supply from land. To study those responses, we used nutrient diffusing substrates to manipulate resource supply to biofilm communities along regional gradients in stream temperature, riparian shading, and dissolved organic carbon (DOC) loading in Arctic Sweden. We found strong nitrogen (N) limitation across this gradient for gross primary production, community respiration and chlorophyll-a accumulation. For unamended biofilms, activity and biomass accrual were not closely related to any single physical or chemical driver across this region. However, the magnitude of biofilm response to N addition was: in tundra streams, biofilm response was constrained by thermal regimes, whereas variation in light availability regulated this response in birch and coniferous forest streams. Furthermore, heterotrophic responses to experimental N addition increased across the region with greater stream water concentrations of DOC relative to inorganic N. Thus, future shifts in resource supply to these ecosystems are likely to interact with other concurrent environmental changes to regulate stream productivity. Indeed, our results suggest that in the absence of increased nutrient inputs, Arctic streams will be less sensitive to future changes in other habitat variables such as temperature and DOC loading.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Myrstener, Maria and Rocher-Ros, Gerard and Burrows, Ryan M. and Bergström, Ann-Kristin and Giesler, Reiner and Sponseller, Ryan A.},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.14117},\n\tkeywords = {\\#nosource, Arctic, Bioassay, Biofilm, Climate Change, Co-limitation, Nitrogen limitation, Nutrient addition, Stream productivity, bioassay, biofilm, climate change, colimitation, nitrogen limitation, nutrient addition, stream productivity},\n\tpages = {3680--3691},\n}\n\n\n\n\n\n Climate change is rapidly reshaping Arctic landscapes through shifts in vegetation cover and productivity, soil resource mobilization, and hydrological regimes. The implications of these changes for stream ecosystems and food webs is unclear and will depend largely on microbial biofilm responses to concurrent shifts in temperature, light, and resource supply from land. To study those responses, we used nutrient diffusing substrates to manipulate resource supply to biofilm communities along regional gradients in stream temperature, riparian shading, and dissolved organic carbon (DOC) loading in Arctic Sweden. We found strong nitrogen (N) limitation across this gradient for gross primary production, community respiration and chlorophyll-a accumulation. For unamended biofilms, activity and biomass accrual were not closely related to any single physical or chemical driver across this region. However, the magnitude of biofilm response to N addition was: in tundra streams, biofilm response was constrained by thermal regimes, whereas variation in light availability regulated this response in birch and coniferous forest streams. Furthermore, heterotrophic responses to experimental N addition increased across the region with greater stream water concentrations of DOC relative to inorganic N. Thus, future shifts in resource supply to these ecosystems are likely to interact with other concurrent environmental changes to regulate stream productivity. Indeed, our results suggest that in the absence of increased nutrient inputs, Arctic streams will be less sensitive to future changes in other habitat variables such as temperature and DOC loading.\n
\n\n\n\n \n\n \n \n \n \n \n \n Patchy field sampling biases understanding of climate change impacts across the Arctic.\n \n \n \n \n\n\n \n Metcalfe, D. B.; Hermans, T. D. G.; Ahlstrand, J.; Becker, M.; Berggren, M.; Björk, R. G.; Björkman, M. P.; Blok, D.; Chaudhary, N.; Chisholm, C.; Classen, A. T.; Hasselquist, N. J.; Jonsson, M.; Kristensen, J. A.; Kumordzi, B. B.; Lee, H.; Mayor, J. R.; Prevéy, J.; Pantazatou, K.; Rousk, J.; Sponseller, R. A.; Sundqvist, M. K.; Tang, J.; Uddling, J.; Wallin, G.; Zhang, W.; Ahlström, A.; Tenenbaum, D. E.; and Abdi, A. M.\n\n\n \n\n\n\n Nature Ecology & Evolution, 2(9): 1443–1448. September 2018.\n Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{metcalfe_patchy_2018,\n\ttitle = {Patchy field sampling biases understanding of climate change impacts across the {Arctic}},\n\tvolume = {2},\n\tcopyright = {2018 The Author(s), under exclusive licence to Springer Nature Limited},\n\tissn = {2397-334X},\n\turl = {https://www.nature.com/articles/s41559-018-0612-5},\n\tdoi = {10.1038/s41559-018-0612-5},\n\tabstract = {Effective societal responses to rapid climate change in the Arctic rely on an accurate representation of region-specific ecosystem properties and processes. However, this is limited by the scarcity and patchy distribution of field measurements. Here, we use a comprehensive, geo-referenced database of primary field measurements in 1,840 published studies across the Arctic to identify statistically significant spatial biases in field sampling and study citation across this globally important region. We find that 31\\% of all study citations are derived from sites located within 50 km of just two research sites: Toolik Lake in the USA and Abisko in Sweden. Furthermore, relatively colder, more rapidly warming and sparsely vegetated sites are under-sampled and under-recognized in terms of citations, particularly among microbiology-related studies. The poorly sampled and cited areas, mainly in the Canadian high-Arctic archipelago and the Arctic coastline of Russia, constitute a large fraction of the Arctic ice-free land area. Our results suggest that the current pattern of sampling and citation may bias the scientific consensuses that underpin attempts to accurately predict and effectively mitigate climate change in the region. Further work is required to increase both the quality and quantity of sampling, and incorporate existing literature from poorly cited areas to generate a more representative picture of Arctic climate change and its environmental impacts.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2024-03-27},\n\tjournal = {Nature Ecology \\& Evolution},\n\tauthor = {Metcalfe, Daniel B. and Hermans, Thirze D. G. and Ahlstrand, Jenny and Becker, Michael and Berggren, Martin and Björk, Robert G. and Björkman, Mats P. and Blok, Daan and Chaudhary, Nitin and Chisholm, Chelsea and Classen, Aimée T. and Hasselquist, Niles J. and Jonsson, Micael and Kristensen, Jeppe A. and Kumordzi, Bright B. and Lee, Hanna and Mayor, Jordan R. and Prevéy, Janet and Pantazatou, Karolina and Rousk, Johannes and Sponseller, Ryan A. and Sundqvist, Maja K. and Tang, Jing and Uddling, Johan and Wallin, Göran and Zhang, Wenxin and Ahlström, Anders and Tenenbaum, David E. and Abdi, Abdulhakim M.},\n\tmonth = sep,\n\tyear = {2018},\n\tnote = {Publisher: Nature Publishing Group},\n\tkeywords = {\\#nosource, Climate change, Environmental sciences, Research data},\n\tpages = {1443--1448},\n}\n\n\n\n\n\n Effective societal responses to rapid climate change in the Arctic rely on an accurate representation of region-specific ecosystem properties and processes. However, this is limited by the scarcity and patchy distribution of field measurements. Here, we use a comprehensive, geo-referenced database of primary field measurements in 1,840 published studies across the Arctic to identify statistically significant spatial biases in field sampling and study citation across this globally important region. We find that 31% of all study citations are derived from sites located within 50 km of just two research sites: Toolik Lake in the USA and Abisko in Sweden. Furthermore, relatively colder, more rapidly warming and sparsely vegetated sites are under-sampled and under-recognized in terms of citations, particularly among microbiology-related studies. The poorly sampled and cited areas, mainly in the Canadian high-Arctic archipelago and the Arctic coastline of Russia, constitute a large fraction of the Arctic ice-free land area. Our results suggest that the current pattern of sampling and citation may bias the scientific consensuses that underpin attempts to accurately predict and effectively mitigate climate change in the region. Further work is required to increase both the quality and quantity of sampling, and incorporate existing literature from poorly cited areas to generate a more representative picture of Arctic climate change and its environmental impacts.\n
\n\n\n\n \n\n \n \n \n \n \n \n The role of bryophytes for tree seedling responses to winter climate change: Implications for the stress gradient hypothesis.\n \n \n \n \n\n\n \n Lett, S.; Wardle, D. A.; Nilsson, M.; Teuber, L. M.; and Dorrepaal, E.\n\n\n \n\n\n\n Journal of Ecology, 106(3): 1142–1155. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.12898\n\n\n\n
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\n\n\n@article{lett_role_2018,\n\ttitle = {The role of bryophytes for tree seedling responses to winter climate change: {Implications} for the stress gradient hypothesis},\n\tvolume = {106},\n\tcopyright = {© 2017 The Authors. Journal of Ecology © 2017 British Ecological Society},\n\tissn = {1365-2745},\n\tshorttitle = {The role of bryophytes for tree seedling responses to winter climate change},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.12898},\n\tdoi = {10.1111/1365-2745.12898},\n\tabstract = {When tree seedlings establish beyond the current tree line due to climate warming, they encounter existing vegetation, such as bryophytes that often dominate in arctic and alpine tundra. The stress gradient hypothesis (SGH) predicts that plant interactions in tundra become increasingly negative as climate warms and conditions become less harsh. However, for seedlings, climate warming might not result in lower winter stress, if insulating snow cover is reduced. We aimed to understand if bryophytes facilitate seedling survival in a changing winter climate and if these effects of bryophytes on tree seedlings comply with the SGH along elevational gradients under contrasting snow conditions. In the Swedish subarctic, we transplanted intact bryophyte cores covered by each of three bryophyte species and bryophyte-free control soil from above the tree line to two field common garden sites, representing current and future tree line air temperature conditions (i.e. current tree line elevation and a lower, warmer, elevation below the tree line). We planted seedlings of Betula pubescens and Pinus sylvestris into these cores and subjected them to experimental manipulation of snow cover during one winter. In agreement with the SGH, milder conditions caused by increased snow cover enhanced the generally negative or neutral effects of bryophytes on seedlings immediately after winter. Furthermore, survival of P. sylvestris seedlings after one full year was higher at lower elevation, especially when snow cover was thinner. However, in contrast with the SGH, impacts of bryophytes on over-winter survival of seedlings did not differ between elevations, and impacts on survival of B. pubescens seedlings after 1 year was more negative at lower elevation. Bryophyte species differed in their effect on seedling survival after winter, but these differences were not related to their insulating capacity. Synthesis. Our study demonstrates that interactions from bryophytes can modify the impacts of winter climate change on tree seedlings, and vice versa. These responses do not always comply with SGH, but could ultimately have consequences for large-scale ecological processes such as tree line shifts. These new insights need to be taken into account in predictions of plant species responses to climate change.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {Lett, Signe and Wardle, David A. and Nilsson, Marie-Charlotte and Teuber, Laurenz M. and Dorrepaal, Ellen},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.12898},\n\tkeywords = {\\#nosource, B. pubescens, P. sylvestris, alpine, climate change, competition, facilitation, plant–plant interactions, snow cover, subarctic, tree line},\n\tpages = {1142--1155},\n}\n\n\n\n\n\n When tree seedlings establish beyond the current tree line due to climate warming, they encounter existing vegetation, such as bryophytes that often dominate in arctic and alpine tundra. The stress gradient hypothesis (SGH) predicts that plant interactions in tundra become increasingly negative as climate warms and conditions become less harsh. However, for seedlings, climate warming might not result in lower winter stress, if insulating snow cover is reduced. We aimed to understand if bryophytes facilitate seedling survival in a changing winter climate and if these effects of bryophytes on tree seedlings comply with the SGH along elevational gradients under contrasting snow conditions. In the Swedish subarctic, we transplanted intact bryophyte cores covered by each of three bryophyte species and bryophyte-free control soil from above the tree line to two field common garden sites, representing current and future tree line air temperature conditions (i.e. current tree line elevation and a lower, warmer, elevation below the tree line). We planted seedlings of Betula pubescens and Pinus sylvestris into these cores and subjected them to experimental manipulation of snow cover during one winter. In agreement with the SGH, milder conditions caused by increased snow cover enhanced the generally negative or neutral effects of bryophytes on seedlings immediately after winter. Furthermore, survival of P. sylvestris seedlings after one full year was higher at lower elevation, especially when snow cover was thinner. However, in contrast with the SGH, impacts of bryophytes on over-winter survival of seedlings did not differ between elevations, and impacts on survival of B. pubescens seedlings after 1 year was more negative at lower elevation. Bryophyte species differed in their effect on seedling survival after winter, but these differences were not related to their insulating capacity. Synthesis. Our study demonstrates that interactions from bryophytes can modify the impacts of winter climate change on tree seedlings, and vice versa. These responses do not always comply with SGH, but could ultimately have consequences for large-scale ecological processes such as tree line shifts. These new insights need to be taken into account in predictions of plant species responses to climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Towards an Improved Conceptualization of Riparian Zones in Boreal Forest Headwaters.\n \n \n \n \n\n\n \n Ledesma, J. L. J.; Futter, M. N.; Blackburn, M.; Lidman, F.; Grabs, T.; Sponseller, R. A.; Laudon, H.; Bishop, K. H.; and Köhler, S. J.\n\n\n \n\n\n\n Ecosystems, 21(2): 297–315. March 2018.\n \n\n\n\n
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\n\n\n@article{ledesma_towards_2018,\n\ttitle = {Towards an {Improved} {Conceptualization} of {Riparian} {Zones} in {Boreal} {Forest} {Headwaters}},\n\tvolume = {21},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-017-0149-5},\n\tdoi = {10.1007/s10021-017-0149-5},\n\tabstract = {The boreal ecoregion supports about one-third of the world’s forest. Over 90\\% of boreal forest streams are found in headwaters, where terrestrial–aquatic interfaces are dominated by organic matter (OM)-rich riparian zones (RZs). Because these transition zones are key features controlling catchment biogeochemistry, appropriate RZ conceptualizations are needed to sustainably manage surface water quality in the face of a changing climate and increased demands for forest biomass. Here we present a simple, yet comprehensive, conceptualization of RZ function based on hydrological connectivity, biogeochemical processes, and spatial heterogeneity. We consider four dimensions of hydrological connectivity: (1) laterally along hillslopes, (2) longitudinally along the stream, (3) vertically down the riparian profile, and (4) temporally through event-based and seasonal changes in hydrology. Of particular importance is the vertical dimension, characterized by a ‘Dominant Source Layer’ that has the highest contribution to solute and water fluxes to streams. In addition to serving as the primary source of OM to boreal streams, RZs shape water chemistry through two sets of OM-dependent biogeochemical processes: (1) transport and retention of OM-associated material and (2) redox-mediated transformations controlled by RZ water residence time and availability of labile OM. These processes can lead to both retention and release of pollutants. Variations in width, hydrological connectivity, and OM storage drive spatial heterogeneity in RZ biogeochemical function. This conceptualization provides a useful theoretical framework for environmental scientists and ecologically sustainable and economically effective forest management in the boreal region and elsewhere, where forest headwaters are dominated by low-gradient, OM-rich RZs.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Ledesma, José L. J. and Futter, Martyn N. and Blackburn, M. and Lidman, Fredrik and Grabs, Thomas and Sponseller, Ryan A. and Laudon, Hjalmar and Bishop, Kevin H. and Köhler, Stephan J.},\n\tmonth = mar,\n\tyear = {2018},\n\tkeywords = {\\#nosource, catchment biogeochemistry, catchment heterogeneity, forest management, hydrological connectivity, redox, riparian buffer, soil organic matter, terrestrial–aquatic interface, water quality},\n\tpages = {297--315},\n}\n\n\n\n\n\n The boreal ecoregion supports about one-third of the world’s forest. Over 90% of boreal forest streams are found in headwaters, where terrestrial–aquatic interfaces are dominated by organic matter (OM)-rich riparian zones (RZs). Because these transition zones are key features controlling catchment biogeochemistry, appropriate RZ conceptualizations are needed to sustainably manage surface water quality in the face of a changing climate and increased demands for forest biomass. Here we present a simple, yet comprehensive, conceptualization of RZ function based on hydrological connectivity, biogeochemical processes, and spatial heterogeneity. We consider four dimensions of hydrological connectivity: (1) laterally along hillslopes, (2) longitudinally along the stream, (3) vertically down the riparian profile, and (4) temporally through event-based and seasonal changes in hydrology. Of particular importance is the vertical dimension, characterized by a ‘Dominant Source Layer’ that has the highest contribution to solute and water fluxes to streams. In addition to serving as the primary source of OM to boreal streams, RZs shape water chemistry through two sets of OM-dependent biogeochemical processes: (1) transport and retention of OM-associated material and (2) redox-mediated transformations controlled by RZ water residence time and availability of labile OM. These processes can lead to both retention and release of pollutants. Variations in width, hydrological connectivity, and OM storage drive spatial heterogeneity in RZ biogeochemical function. This conceptualization provides a useful theoretical framework for environmental scientists and ecologically sustainable and economically effective forest management in the boreal region and elsewhere, where forest headwaters are dominated by low-gradient, OM-rich RZs.\n
\n\n\n\n \n\n \n \n \n \n \n \n How landscape organization and scale shape catchment hydrology and biogeochemistry: insights from a long-term catchment study.\n \n \n \n \n\n\n \n Laudon, H.; and Sponseller, R. A.\n\n\n \n\n\n\n WIREs Water, 5(2): e1265. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/wat2.1265\n\n\n\n
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\n\n\n@article{laudon_how_2018,\n\ttitle = {How landscape organization and scale shape catchment hydrology and biogeochemistry: insights from a long-term catchment study},\n\tvolume = {5},\n\tcopyright = {© 2017 Wiley Periodicals, Inc.},\n\tissn = {2049-1948},\n\tshorttitle = {How landscape organization and scale shape catchment hydrology and biogeochemistry},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/wat2.1265},\n\tdoi = {10.1002/wat2.1265},\n\tabstract = {Catchment science plays a critical role in the protection of water resources in the face of ongoing changes in climate, long-range transport of air pollutants, and land use. Addressing these challenges, however, requires improved understanding of how, when, and where changes in water quantity and quality occur within river networks. To reach these goals, we must recognize how different catchment features are organized to regulate surface chemistry at multiple scales, from processes controlling headwaters, to the downstream mixing of water from multiple landscape sources and deep aquifers. Here we synthesize 30-years of hydrological and biogeochemical research from the Krycklan catchment study (KCS) in northern Sweden to demonstrate the benefits of coupling long-term monitoring with multi-scale research to advance our understanding of catchment functioning across space and time. We show that the regulation of hydrological and biogeochemical patterns in the KCS can be decomposed into four, hierarchically structured landscape features that include: (1) transmissivity and reactivity of dominant source layers within riparian soils, (2) spatial arrangement of groundwater input zones that govern water and solute fluxes at reach- to segment-scales, (3) landscape scale heterogeneity (forests, mires, and lakes) that generates unique biogeochemical signals downstream, and (4) broad-scale mixing of surface streams with deep groundwater contributions. While this set of features are perhaps specific to the study region, analogous hierarchical controls are likely to be widespread. Resolving these scale dependent processes is important for predicting how, when, and where different environmental changes may influence patterns of surface water chemistry within river networks. WIREs Water 2018, 5:e1265. doi: 10.1002/wat2.1265 This article is categorized under: Science of Water {\\textgreater} Hydrological Processes Science of Water {\\textgreater} Water and Environmental Change Science of Water {\\textgreater} Methods},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {WIREs Water},\n\tauthor = {Laudon, Hjalmar and Sponseller, Ryan A.},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/wat2.1265},\n\tkeywords = {\\#nosource},\n\tpages = {e1265},\n}\n\n\n\n\n\n Catchment science plays a critical role in the protection of water resources in the face of ongoing changes in climate, long-range transport of air pollutants, and land use. Addressing these challenges, however, requires improved understanding of how, when, and where changes in water quantity and quality occur within river networks. To reach these goals, we must recognize how different catchment features are organized to regulate surface chemistry at multiple scales, from processes controlling headwaters, to the downstream mixing of water from multiple landscape sources and deep aquifers. Here we synthesize 30-years of hydrological and biogeochemical research from the Krycklan catchment study (KCS) in northern Sweden to demonstrate the benefits of coupling long-term monitoring with multi-scale research to advance our understanding of catchment functioning across space and time. We show that the regulation of hydrological and biogeochemical patterns in the KCS can be decomposed into four, hierarchically structured landscape features that include: (1) transmissivity and reactivity of dominant source layers within riparian soils, (2) spatial arrangement of groundwater input zones that govern water and solute fluxes at reach- to segment-scales, (3) landscape scale heterogeneity (forests, mires, and lakes) that generates unique biogeochemical signals downstream, and (4) broad-scale mixing of surface streams with deep groundwater contributions. While this set of features are perhaps specific to the study region, analogous hierarchical controls are likely to be widespread. Resolving these scale dependent processes is important for predicting how, when, and where different environmental changes may influence patterns of surface water chemistry within river networks. WIREs Water 2018, 5:e1265. doi: 10.1002/wat2.1265 This article is categorized under: Science of Water \\textgreater Hydrological Processes Science of Water \\textgreater Water and Environmental Change Science of Water \\textgreater Methods\n
\n\n\n\n \n\n \n \n \n \n \n \n Catchment properties predict autochthony in stream filter feeders.\n \n \n \n \n\n\n \n Jonsson, M.; Polvi, L. E.; Sponseller, R. A.; and Stenroth, K.\n\n\n \n\n\n\n Hydrobiologia, 815(1): 83–95. June 2018.\n \n\n\n\n
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\n\n\n@article{jonsson_catchment_2018,\n\ttitle = {Catchment properties predict autochthony in stream filter feeders},\n\tvolume = {815},\n\tissn = {1573-5117},\n\turl = {https://doi.org/10.1007/s10750-018-3553-8},\n\tdoi = {10.1007/s10750-018-3553-8},\n\tabstract = {Stream ecological theory predicts that the use of allochthonous resources declines with increasing channel width, while at the same time primary production and autochthonous carbon use by consumers increase. Although these expectations have found support in several studies, it is not well known how terrestrial runoff and/or inputs of primary production from lakes alter these longitudinal patterns. To investigate this, we analyzed the diet of filter-feeding black fly and caddisfly larvae from 23 boreal streams, encompassing gradients in drainage area, land cover and land use, and distance to nearest upstream lake outlet. In five of these streams, we also sampled repeatedly during autumn to test if allochthony of filter feeders increases over time as new litter inputs are processed. Across sites, filter-feeder autochthony was 21.1–75.1\\%, did not differ between black fly and caddisfly larvae, was not positively related to drainage area, and did not decrease with distance from lakes. Instead, lake and wetland cover promoted filter-feeder autochthony independently of stream size, whereas catchment-scale forest cover and forestry reduced autochthony. Further, we found no seasonal increase in allochthony, indicating low assimilation of particles derived from autumn litter fall. Hence, catchment properties, rather than local conditions, can influence levels of autochthony in boreal streams.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Hydrobiologia},\n\tauthor = {Jonsson, Micael and Polvi, Lina E. and Sponseller, Ryan A. and Stenroth, Karolina},\n\tmonth = jun,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Allochthony, Aquatic insects, Autochthony, Land cover, Land use, Stream},\n\tpages = {83--95},\n}\n\n\n\n\n\n Stream ecological theory predicts that the use of allochthonous resources declines with increasing channel width, while at the same time primary production and autochthonous carbon use by consumers increase. Although these expectations have found support in several studies, it is not well known how terrestrial runoff and/or inputs of primary production from lakes alter these longitudinal patterns. To investigate this, we analyzed the diet of filter-feeding black fly and caddisfly larvae from 23 boreal streams, encompassing gradients in drainage area, land cover and land use, and distance to nearest upstream lake outlet. In five of these streams, we also sampled repeatedly during autumn to test if allochthony of filter feeders increases over time as new litter inputs are processed. Across sites, filter-feeder autochthony was 21.1–75.1%, did not differ between black fly and caddisfly larvae, was not positively related to drainage area, and did not decrease with distance from lakes. Instead, lake and wetland cover promoted filter-feeder autochthony independently of stream size, whereas catchment-scale forest cover and forestry reduced autochthony. Further, we found no seasonal increase in allochthony, indicating low assimilation of particles derived from autumn litter fall. Hence, catchment properties, rather than local conditions, can influence levels of autochthony in boreal streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Identifying and assessing the potential hydrological function of past artificial forest drainage.\n \n \n \n \n\n\n \n Hasselquist, E. M.; Lidberg, W.; Sponseller, R. A.; Ågren, A.; and Laudon, H.\n\n\n \n\n\n\n Ambio, 47(5): 546–556. September 2018.\n \n\n\n\n
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\n\n\n@article{hasselquist_identifying_2018,\n\ttitle = {Identifying and assessing the potential hydrological function of past artificial forest drainage},\n\tvolume = {47},\n\tissn = {1654-7209},\n\turl = {https://doi.org/10.1007/s13280-017-0984-9},\n\tdoi = {10.1007/s13280-017-0984-9},\n\tabstract = {Drainage of forested wetlands for increased timber production has profoundly altered the hydrology and water quality of their downstream waterways. Some ditches need network maintenance (DNM), but potential positive effects on tree productivity must be balanced against environmental impacts. Currently, no clear guidelines exist for DNM that strike this balance. Our study helps begin to prioritise DNM by: (1) quantifying ditches by soil type in the 68 km2 Krycklan Catchment Study in northern Sweden and (2) using upslope catchment area algorithms on new high-resolution digital elevation models to determine their likelihood to drain water. Ditches nearly doubled the size of the stream network (178–327 km) and 17\\% of ditches occurred on well-draining sedimentary soils, presumably making DNM unwarranted. Modelling results suggest that 25–50\\% of ditches may never support flow. With new laser scanning technology, simple mapping and modelling methods can locate ditches and model their function, facilitating efforts to balance DNM with environmental impacts.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Ambio},\n\tauthor = {Hasselquist, Eliza Maher and Lidberg, William and Sponseller, Ryan A. and Ågren, Anneli and Laudon, Hjalmar},\n\tmonth = sep,\n\tyear = {2018},\n\tkeywords = {\\#nosource, DEM, Flow accumulation model, Hydrology, LiDAR, Peatland, Terrain-based prediction},\n\tpages = {546--556},\n}\n\n\n\n\n\n Drainage of forested wetlands for increased timber production has profoundly altered the hydrology and water quality of their downstream waterways. Some ditches need network maintenance (DNM), but potential positive effects on tree productivity must be balanced against environmental impacts. Currently, no clear guidelines exist for DNM that strike this balance. Our study helps begin to prioritise DNM by: (1) quantifying ditches by soil type in the 68 km2 Krycklan Catchment Study in northern Sweden and (2) using upslope catchment area algorithms on new high-resolution digital elevation models to determine their likelihood to drain water. Ditches nearly doubled the size of the stream network (178–327 km) and 17% of ditches occurred on well-draining sedimentary soils, presumably making DNM unwarranted. Modelling results suggest that 25–50% of ditches may never support flow. With new laser scanning technology, simple mapping and modelling methods can locate ditches and model their function, facilitating efforts to balance DNM with environmental impacts.\n
\n\n\n\n \n\n \n \n \n \n \n \n Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities.\n \n \n \n \n\n\n \n George, T. S.; Giles, C. D.; Menezes-Blackburn, D.; Condron, L. M.; Gama-Rodrigues, A. C.; Jaisi, D.; Lang, F.; Neal, A. L.; Stutter, M. I.; Almeida, D. S.; Bol, R.; Cabugao, K. G.; Celi, L.; Cotner, J. B.; Feng, G.; Goll, D. S.; Hallama, M.; Krueger, J.; Plassard, C.; Rosling, A.; Darch, T.; Fraser, T.; Giesler, R.; Richardson, A. E.; Tamburini, F.; Shand, C. A.; Lumsdon, D. G.; Zhang, H.; Blackwell, M. S. A.; Wearing, C.; Mezeli, M. M.; Almås, Å. R.; Audette, Y.; Bertrand, I.; Beyhaut, E.; Boitt, G.; Bradshaw, N.; Brearley, C. A.; Bruulsema, T. W.; Ciais, P.; Cozzolino, V.; Duran, P. C.; Mora, M. L.; de Menezes, A. B.; Dodd, R. J.; Dunfield, K.; Engl, C.; Frazão, J. J.; Garland, G.; González Jiménez, J. L.; Graca, J.; Granger, S. J.; Harrison, A. F.; Heuck, C.; Hou, E. Q.; Johnes, P. J.; Kaiser, K.; Kjær, H. A.; Klumpp, E.; Lamb, A. L.; Macintosh, K. A.; Mackay, E. B.; McGrath, J.; McIntyre, C.; McLaren, T.; Mészáros, E.; Missong, A.; Mooshammer, M.; Negrón, C. P.; Nelson, L. A.; Pfahler, V.; Poblete-Grant, P.; Randall, M.; Seguel, A.; Seth, K.; Smith, A. C.; Smits, M. M.; Sobarzo, J. A.; Spohn, M.; Tawaraya, K.; Tibbett, M.; Voroney, P.; Wallander, H.; Wang, L.; Wasaki, J.; and Haygarth, P. M.\n\n\n \n\n\n\n Plant and Soil, 427(1): 191–208. June 2018.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{george_organic_2018,\n\ttitle = {Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities},\n\tvolume = {427},\n\tissn = {1573-5036},\n\tshorttitle = {Organic phosphorus in the terrestrial environment},\n\turl = {https://doi.org/10.1007/s11104-017-3391-x},\n\tdoi = {10.1007/s11104-017-3391-x},\n\tabstract = {The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Plant and Soil},\n\tauthor = {George, T. S. and Giles, C. D. and Menezes-Blackburn, D. and Condron, L. M. and Gama-Rodrigues, A. C. and Jaisi, D. and Lang, F. and Neal, A. L. and Stutter, M. I. and Almeida, D. S. and Bol, R. and Cabugao, K. G. and Celi, L. and Cotner, J. B. and Feng, G. and Goll, D. S. and Hallama, M. and Krueger, J. and Plassard, C. and Rosling, A. and Darch, T. and Fraser, T. and Giesler, R. and Richardson, A. E. and Tamburini, F. and Shand, C. A. and Lumsdon, D. G. and Zhang, H. and Blackwell, M. S. A. and Wearing, C. and Mezeli, M. M. and Almås, Å. R. and Audette, Y. and Bertrand, I. and Beyhaut, E. and Boitt, G. and Bradshaw, N. and Brearley, C. A. and Bruulsema, T. W. and Ciais, P. and Cozzolino, V. and Duran, P. C. and Mora, M. L. and de Menezes, A. B. and Dodd, R. J. and Dunfield, K. and Engl, C. and Frazão, J. J. and Garland, G. and González Jiménez, J. L. and Graca, J. and Granger, S. J. and Harrison, A. F. and Heuck, C. and Hou, E. Q. and Johnes, P. J. and Kaiser, K. and Kjær, H. A. and Klumpp, E. and Lamb, A. L. and Macintosh, K. A. and Mackay, E. B. and McGrath, J. and McIntyre, C. and McLaren, T. and Mészáros, E. and Missong, A. and Mooshammer, M. and Negrón, C. P. and Nelson, L. A. and Pfahler, V. and Poblete-Grant, P. and Randall, M. and Seguel, A. and Seth, K. and Smith, A. C. and Smits, M. M. and Sobarzo, J. A. and Spohn, M. and Tawaraya, K. and Tibbett, M. and Voroney, P. and Wallander, H. and Wang, L. and Wasaki, J. and Haygarth, P. M.},\n\tmonth = jun,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Ecosystems services, Method development, Microbiome, Modelling, Organic phosphorus, Stoichiometry},\n\tpages = {191--208},\n}\n\n\n\n\n\n The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction.\n
\n\n\n\n \n\n \n \n \n \n \n \n Decreased cryogenic disturbance: one of the potential mechanisms behind the vegetation change in the Arctic.\n \n \n \n \n\n\n \n Becher, M.; Olofsson, J.; Berglund, L.; and Klaminder, J.\n\n\n \n\n\n\n Polar Biology, 41(1): 101–110. January 2018.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{becher_decreased_2018,\n\ttitle = {Decreased cryogenic disturbance: one of the potential mechanisms behind the vegetation change in the {Arctic}},\n\tvolume = {41},\n\tissn = {1432-2056},\n\tshorttitle = {Decreased cryogenic disturbance},\n\turl = {https://doi.org/10.1007/s00300-017-2173-5},\n\tdoi = {10.1007/s00300-017-2173-5},\n\tabstract = {During the last few decades, the Arctic has experienced large-scale vegetation changes. Understanding the mechanisms behind this vegetation change is crucial for our ability to predict future changes. This study tested the hypothesis that decreased cryogenic disturbances cause vegetation change in patterned ground study fields (non-sorted circles) in Abisko, Sweden during the last few decades. The hypothesis was tested by surveying the composition of plant communities across a gradient in cryogenic disturbance and by reinvestigating plant communities previously surveyed in the 1980s to scrutinise how these communities changed in response to reduced cryogenic disturbance. Whereas the historical changes in species occurrence associated with decreased cryogenic disturbances were relatively consistent with the changes along the contemporary gradient of cryogenic disturbances, the species abundance revealed important transient changes highly dependent on the initial plant community composition. Our results suggest that altered cryogenic disturbances cause temporal changes in vegetation dynamics, but the net effects on vegetation communities depend on the composition of initial plant species.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Polar Biology},\n\tauthor = {Becher, M. and Olofsson, J. and Berglund, L. and Klaminder, J.},\n\tmonth = jan,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Cryogenic disturbance, Differential heave, Freeze/thaw-indices, Non-sorted circles, Patterned ground, Plant abundance},\n\tpages = {101--110},\n}\n\n\n\n\n\n During the last few decades, the Arctic has experienced large-scale vegetation changes. Understanding the mechanisms behind this vegetation change is crucial for our ability to predict future changes. This study tested the hypothesis that decreased cryogenic disturbances cause vegetation change in patterned ground study fields (non-sorted circles) in Abisko, Sweden during the last few decades. The hypothesis was tested by surveying the composition of plant communities across a gradient in cryogenic disturbance and by reinvestigating plant communities previously surveyed in the 1980s to scrutinise how these communities changed in response to reduced cryogenic disturbance. Whereas the historical changes in species occurrence associated with decreased cryogenic disturbances were relatively consistent with the changes along the contemporary gradient of cryogenic disturbances, the species abundance revealed important transient changes highly dependent on the initial plant community composition. Our results suggest that altered cryogenic disturbances cause temporal changes in vegetation dynamics, but the net effects on vegetation communities depend on the composition of initial plant species.\n
\n\n\n\n \n\n \n \n \n \n \n \n Urine is an important nitrogen source for plants irrespective of vegetation composition in an Arctic tundra: Insights from a 15N-enriched urea tracer experiment.\n \n \n \n \n\n\n \n Barthelemy, H.; Stark, S.; Michelsen, A.; and Olofsson, J.\n\n\n \n\n\n\n Journal of Ecology, 106(1): 367–378. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.12820\n\n\n\n
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\n\n\n@article{barthelemy_urine_2018,\n\ttitle = {Urine is an important nitrogen source for plants irrespective of vegetation composition in an {Arctic} tundra: {Insights} from a {15N}-enriched urea tracer experiment},\n\tvolume = {106},\n\tcopyright = {© 2017 The Authors. Journal of Ecology © 2017 British Ecological Society},\n\tissn = {1365-2745},\n\tshorttitle = {Urine is an important nitrogen source for plants irrespective of vegetation composition in an {Arctic} tundra},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.12820},\n\tdoi = {10.1111/1365-2745.12820},\n\tabstract = {Mammalian herbivores can strongly influence nitrogen (N) cycling and herbivore urine could be a central component of the N cycle in grazed ecosystems. Despite its potential role for ecosystem productivity and functioning, the fate of N derived from urine has rarely been investigated in grazed ecosystems. This study explored the fate of 15N-enriched urea in tundra sites that have been either lightly or intensively grazed by reindeer for more than 50 years. We followed the fate of the 15N applied to the plant canopy, at 2 weeks and 1 year after tracer addition, in the different ecosystem N pools. 15N-urea was rapidly incorporated in cryptogams and in above-ground parts of vascular plants, while the soil microbial pool and plant roots sequestered only a marginal proportion. Furthermore, the litter layer constituted a large sink for the 15N-urea, at least in the short term, indicating a high biological activity in the litter layer and high immobilization in the first phases of organic matter decomposition. Mosses and lichens still constituted the largest sink for the 15N-urea 1 year after tracer addition at both levels of grazing intensity demonstrating their large ability to capture and retain N from urine. Despite large fundamental differences in their traits, deciduous and evergreen shrubs were just as efficient as graminoids in taking up the 15N-urea. The total recovery of 15N-urea was lower in the intensively grazed sites, suggesting that reindeer reduce ecosystem N retention. Synthesis. The rapid incorporation of the applied 15N-urea indicates that arctic plants can take advantage of a pulse of incoming N from urine. In addition, δ15N values of all taxa in the heavily grazed sites converged towards the δ15N values for urine, bringing further evidence that urine is an important N source for plants in grazed tundra ecosystems.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {Barthelemy, Hélène and Stark, Sari and Michelsen, Anders and Olofsson, Johan},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.12820},\n\tkeywords = {\\#nosource, Arctic tundra, N labelling, above- and belowground linkages, cryptogams, grazing intensity, microbial N biomass, nutrient cycling, plant nutrient uptake, plant–herbivore interactions, urine},\n\tpages = {367--378},\n}\n\n\n\n\n\n Mammalian herbivores can strongly influence nitrogen (N) cycling and herbivore urine could be a central component of the N cycle in grazed ecosystems. Despite its potential role for ecosystem productivity and functioning, the fate of N derived from urine has rarely been investigated in grazed ecosystems. This study explored the fate of 15N-enriched urea in tundra sites that have been either lightly or intensively grazed by reindeer for more than 50 years. We followed the fate of the 15N applied to the plant canopy, at 2 weeks and 1 year after tracer addition, in the different ecosystem N pools. 15N-urea was rapidly incorporated in cryptogams and in above-ground parts of vascular plants, while the soil microbial pool and plant roots sequestered only a marginal proportion. Furthermore, the litter layer constituted a large sink for the 15N-urea, at least in the short term, indicating a high biological activity in the litter layer and high immobilization in the first phases of organic matter decomposition. Mosses and lichens still constituted the largest sink for the 15N-urea 1 year after tracer addition at both levels of grazing intensity demonstrating their large ability to capture and retain N from urine. Despite large fundamental differences in their traits, deciduous and evergreen shrubs were just as efficient as graminoids in taking up the 15N-urea. The total recovery of 15N-urea was lower in the intensively grazed sites, suggesting that reindeer reduce ecosystem N retention. Synthesis. The rapid incorporation of the applied 15N-urea indicates that arctic plants can take advantage of a pulse of incoming N from urine. In addition, δ15N values of all taxa in the heavily grazed sites converged towards the δ15N values for urine, bringing further evidence that urine is an important N source for plants in grazed tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lake morphometry moderates the relationship between water color and fish biomass in small boreal lakes.\n \n \n \n \n\n\n \n Seekell, D. A.; Byström, P.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 63(5): 2171–2178. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10931\n\n\n\n
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\n\n\n@article{seekell_lake_2018,\n\ttitle = {Lake morphometry moderates the relationship between water color and fish biomass in small boreal lakes},\n\tvolume = {63},\n\tcopyright = {© 2018 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.10931},\n\tdoi = {10.1002/lno.10931},\n\tabstract = {Lake morphometry may moderate the effects of water color on fish biomass in boreal lakes, but empirical evidence is scarce because there are a limited number of lakes for which both water color and bathymetry have been measured. We evaluated variations in catch-per-unit-effort (CPUE), an indicator of fish biomass, across orthogonal gradients of light extinction and mean depth in 16 small Swedish lakes (mean depth 1.7–4.8 m, surface area 1–10 ha). Multiple regression coefficients indicated that the effect of light extinction on CPUE was negative, and that the relationship was more negative for deeper lakes than it was for shallower lakes. The pattern was strongest for lakes with mean depths between 2.1 m and 3.5 m. We estimated that 26\\% of small lakes in boreal Sweden fall within this mean depth range. These results contribute to the growing understanding of how variations in water color and lake morphometry influence patterns of fish biomass across the boreal landscape.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Seekell, David A. and Byström, Pär and Karlsson, Jan},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10931},\n\tkeywords = {\\#nosource},\n\tpages = {2171--2178},\n}\n\n\n\n\n\n Lake morphometry may moderate the effects of water color on fish biomass in boreal lakes, but empirical evidence is scarce because there are a limited number of lakes for which both water color and bathymetry have been measured. We evaluated variations in catch-per-unit-effort (CPUE), an indicator of fish biomass, across orthogonal gradients of light extinction and mean depth in 16 small Swedish lakes (mean depth 1.7–4.8 m, surface area 1–10 ha). Multiple regression coefficients indicated that the effect of light extinction on CPUE was negative, and that the relationship was more negative for deeper lakes than it was for shallower lakes. The pattern was strongest for lakes with mean depths between 2.1 m and 3.5 m. We estimated that 26% of small lakes in boreal Sweden fall within this mean depth range. These results contribute to the growing understanding of how variations in water color and lake morphometry influence patterns of fish biomass across the boreal landscape.\n
\n\n\n\n \n\n \n \n \n \n \n \n Prolonged exposure does not increase soil microbial community compositional response to warming along geothermal gradients.\n \n \n \n \n\n\n \n Radujković, D.; Verbruggen, E.; Sigurdsson, B. D; Leblans, N. I W; Janssens, I. A; Vicca, S.; and Weedon, J. T\n\n\n \n\n\n\n FEMS Microbiology Ecology, 94(2): fix174. February 2018.\n \n\n\n\n
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\n\n\n@article{radujkovic_prolonged_2018,\n\ttitle = {Prolonged exposure does not increase soil microbial community compositional response to warming along geothermal gradients},\n\tvolume = {94},\n\tissn = {0168-6496},\n\turl = {https://doi.org/10.1093/femsec/fix174},\n\tdoi = {10.1093/femsec/fix174},\n\tabstract = {Global change is expected to affect soil microbial communities through their responsiveness to temperature. It has been proposed that prolonged exposure to elevated temperatures may lead to progressively larger effects on soil microbial community composition. However, due to the relatively short-term nature of most warming experiments, this idea has been challenging to evaluate. The present study took the advantage of natural geothermal gradients (from +1°C to +19°C above ambient) in two subarctic grasslands to test the hypothesis that long-term exposure (\\>50 years) intensifies the effect of warming on microbial community composition compared to short-term exposure (5–7 years). Community profiles from amplicon sequencing of bacterial and fungal rRNA genes did not support this hypothesis: significant changes relative to ambient were observed only starting from the warming intensity of +9°C in the long term and +7°C/+3°C in the short term, for bacteria and fungi, respectively. Our results suggest that microbial communities in high-latitude grasslands will not undergo lasting shifts in community composition under the warming predicted for the coming 100 years (+2.2°C to +8.3°C).},\n\tnumber = {2},\n\turldate = {2024-03-27},\n\tjournal = {FEMS Microbiology Ecology},\n\tauthor = {Radujković, Dajana and Verbruggen, Erik and Sigurdsson, Bjarni D and Leblans, Niki I W and Janssens, Ivan A and Vicca, Sara and Weedon, James T},\n\tmonth = feb,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {fix174},\n}\n\n\n\n\n\n Global change is expected to affect soil microbial communities through their responsiveness to temperature. It has been proposed that prolonged exposure to elevated temperatures may lead to progressively larger effects on soil microbial community composition. However, due to the relatively short-term nature of most warming experiments, this idea has been challenging to evaluate. The present study took the advantage of natural geothermal gradients (from +1°C to +19°C above ambient) in two subarctic grasslands to test the hypothesis that long-term exposure (>50 years) intensifies the effect of warming on microbial community composition compared to short-term exposure (5–7 years). Community profiles from amplicon sequencing of bacterial and fungal rRNA genes did not support this hypothesis: significant changes relative to ambient were observed only starting from the warming intensity of +9°C in the long term and +7°C/+3°C in the short term, for bacteria and fungi, respectively. Our results suggest that microbial communities in high-latitude grasslands will not undergo lasting shifts in community composition under the warming predicted for the coming 100 years (+2.2°C to +8.3°C).\n
\n\n\n\n \n\n \n \n \n \n \n \n Dissolved Organic Matter Controls Seasonal and Spatial Selenium Concentration Variability in Thaw Lakes across a Permafrost Gradient.\n \n \n \n \n\n\n \n Pokrovsky, O. S.; Bueno, M.; Manasypov, R. M.; Shirokova, L. S.; Karlsson, J.; and Amouroux, D.\n\n\n \n\n\n\n Environmental Science & Technology, 52(18): 10254–10262. September 2018.\n Publisher: American Chemical Society\n\n\n\n
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\n\n\n@article{pokrovsky_dissolved_2018,\n\ttitle = {Dissolved {Organic} {Matter} {Controls} {Seasonal} and {Spatial} {Selenium} {Concentration} {Variability} in {Thaw} {Lakes} across a {Permafrost} {Gradient}},\n\tvolume = {52},\n\tissn = {0013-936X},\n\turl = {https://doi.org/10.1021/acs.est.8b00918},\n\tdoi = {10.1021/acs.est.8b00918},\n\tabstract = {Little is known about the sources and processing of selenium, an important toxicant and essential micronutrient, within boreal and sub-arctic environments. Upon climate warming and permafrost thaw, the behavior of Se in northern peatlands becomes an issue of major concern, because a sizable amount of Se can be emitted to the atmosphere from thawing soils and inland water surfaces and exported to downstream waters, thus impacting the Arctic biota. Working toward providing a first-order assessment of spatial and temporal variation of Se concentration in thermokarst waters of the largest frozen peatland in the world, we sampled thaw lakes and rivers across a 750-km latitudinal profile. This profile covered sporadic, discontinuous, and continuous permafrost regions of western Siberia Lowland (WSL), where we measured dissolved ({\\textless}0.45 μm) Se concentration during spring (June), summer (August), and autumn (September). We found maximum Se concentration in the discontinuous permafrost zone. Considering all sampled lakes, Se exhibited linear relationship (R2 = 0.7 to 0.9, p {\\textless} 0.05, n ≈ 70) with dissolved organic carbon (DOC) concentration during summer and autumn. Across the permafrost gradient, the lakes in discontinuous permafrost regions demonstrated stronger relationship with DOC and UV-absorbance compared to lakes in sporadic/isolated and continuous permafrost zones. Both seasonal and spatial features of Se distribution in thermokarst lakes and ponds suggest that Se is mainly released during thawing of frozen peat. Mobilization and immobilization of Se within peat–lake–river watersheds likely occurs as organic and organo-Fe, Al colloids, probably associated with reduced and elemental Se forms. The increase of active layer thickness may enhance leaching of Se in the form of organic complexes with aromatic carbon from the deep horizons of the peat profile. Further, the northward shift of permafrost boundaries in WSL may sizably increase Se concentration in lakes of continuous permafrost zone.},\n\tnumber = {18},\n\turldate = {2024-03-27},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Pokrovsky, Oleg S. and Bueno, Maite and Manasypov, Rinat M. and Shirokova, Liudmila S. and Karlsson, Jan and Amouroux, David},\n\tmonth = sep,\n\tyear = {2018},\n\tnote = {Publisher: American Chemical Society},\n\tkeywords = {\\#nosource},\n\tpages = {10254--10262},\n}\n\n\n\n\n\n Little is known about the sources and processing of selenium, an important toxicant and essential micronutrient, within boreal and sub-arctic environments. Upon climate warming and permafrost thaw, the behavior of Se in northern peatlands becomes an issue of major concern, because a sizable amount of Se can be emitted to the atmosphere from thawing soils and inland water surfaces and exported to downstream waters, thus impacting the Arctic biota. Working toward providing a first-order assessment of spatial and temporal variation of Se concentration in thermokarst waters of the largest frozen peatland in the world, we sampled thaw lakes and rivers across a 750-km latitudinal profile. This profile covered sporadic, discontinuous, and continuous permafrost regions of western Siberia Lowland (WSL), where we measured dissolved (\\textless0.45 μm) Se concentration during spring (June), summer (August), and autumn (September). We found maximum Se concentration in the discontinuous permafrost zone. Considering all sampled lakes, Se exhibited linear relationship (R2 = 0.7 to 0.9, p \\textless 0.05, n ≈ 70) with dissolved organic carbon (DOC) concentration during summer and autumn. Across the permafrost gradient, the lakes in discontinuous permafrost regions demonstrated stronger relationship with DOC and UV-absorbance compared to lakes in sporadic/isolated and continuous permafrost zones. Both seasonal and spatial features of Se distribution in thermokarst lakes and ponds suggest that Se is mainly released during thawing of frozen peat. Mobilization and immobilization of Se within peat–lake–river watersheds likely occurs as organic and organo-Fe, Al colloids, probably associated with reduced and elemental Se forms. The increase of active layer thickness may enhance leaching of Se in the form of organic complexes with aromatic carbon from the deep horizons of the peat profile. Further, the northward shift of permafrost boundaries in WSL may sizably increase Se concentration in lakes of continuous permafrost zone.\n
\n\n\n\n \n\n \n \n \n \n \n \n Industrial and natural compounds in filter-feeding black fly larvae and water in 3 tundra streams.\n \n \n \n \n\n\n \n Kupryianchyk, D.; Giesler, R.; Bidleman, T. F.; Liljelind, P.; Lau, D. C. P.; Sponseller, R. A.; and Andersson, P. L.\n\n\n \n\n\n\n Environmental Toxicology and Chemistry, 37(12): 3011–3017. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/etc.4267\n\n\n\n
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\n\n\n@article{kupryianchyk_industrial_2018,\n\ttitle = {Industrial and natural compounds in filter-feeding black fly larvae and water in 3 tundra streams},\n\tvolume = {37},\n\tcopyright = {© 2018 SETAC},\n\tissn = {1552-8618},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/etc.4267},\n\tdoi = {10.1002/etc.4267},\n\tabstract = {We report concentrations of polychlorinated biphenyls, polybrominated diphenyl ethers, novel flame retardants, and naturally occurring bromoanisoles in water and filter-feeding black fly (Simuliidae) larvae in 3 tundra streams in northern Sweden. The results demonstrate that black fly larvae accumulate a wide range of organic contaminants and can be used as bioindicators of water pollution in Arctic streams. Environ Toxicol Chem 2018;37:3011–3017. © 2018 SETAC},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2024-03-26},\n\tjournal = {Environmental Toxicology and Chemistry},\n\tauthor = {Kupryianchyk, Darya and Giesler, Reiner and Bidleman, Terry F. and Liljelind, Per and Lau, Danny Chun Pong and Sponseller, Ryan A. and Andersson, Patrik L.},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/etc.4267},\n\tkeywords = {\\#nosource, Arctic streams, Bioaccumulation, Emerging pollutants, Fate and transport, Legacy contaminants, Long-range transport, bioaccumulation, emerging pollutants, fate and transport},\n\tpages = {3011--3017},\n}\n\n\n\n\n\n We report concentrations of polychlorinated biphenyls, polybrominated diphenyl ethers, novel flame retardants, and naturally occurring bromoanisoles in water and filter-feeding black fly (Simuliidae) larvae in 3 tundra streams in northern Sweden. The results demonstrate that black fly larvae accumulate a wide range of organic contaminants and can be used as bioindicators of water pollution in Arctic streams. Environ Toxicol Chem 2018;37:3011–3017. © 2018 SETAC\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon Dioxide and Methane Dynamics in a Small Boreal Lake During Winter and Spring Melt Events.\n \n \n \n \n\n\n \n Denfeld, B. A.; Klaus, M.; Laudon, H.; Sponseller, R. A.; and Karlsson, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 123(8): 2527–2540. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018JG004622\n\n\n\n
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\n\n\n@article{denfeld_carbon_2018,\n\ttitle = {Carbon {Dioxide} and {Methane} {Dynamics} in a {Small} {Boreal} {Lake} {During} {Winter} and {Spring} {Melt} {Events}},\n\tvolume = {123},\n\tcopyright = {©2018. American Geophysical Union. All Rights Reserved.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018JG004622},\n\tdoi = {10.1029/2018JG004622},\n\tabstract = {In seasonally ice-covered lakes, carbon dioxide (CO2) and methane (CH4) emission at ice-off can account for a significant fraction of the annual budget. Yet knowledge of the mechanisms controlling below lake-ice carbon (C) dynamics and subsequent CO2 and CH4 emissions at ice-off is limited. To understand the control of below ice C dynamics, and C emissions in spring, we measured spatial variation in CO2, CH4, and dissolved inorganic and organic carbon from ice-on to ice-off, in a small boreal lake during a winter with sporadic melting events. Winter melt events were associated with decreased surface water DOC in the forest-dominated basin and increased surface water CH4 in the mire-dominated basin. At the whole-lake scale, CH4 accumulated below ice throughout the winter, whereas CO2 accumulation was greatest in early winter. Mass-balance estimates suggest that, in addition to the CO2 and CH4 accumulated during winter, external inputs of CO2 and CH4 and internal processing during ice-melt could represent significant sources of C gas emissions during ice-off. Moreover, internal processing of CO2 and CH4 worked in opposition, with production of CO2 and oxidation of CH4 dominating at ice-off. These findings have important implications for how small boreal lakes will respond to warmer winters in the future; increased winter melt events will likely increase external inputs below ice and thus alter the extent and timing of CO2 and CH4 emissions to the atmosphere at ice-off.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2024-03-26},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Denfeld, B. A. and Klaus, M. and Laudon, H. and Sponseller, R. A. and Karlsson, J.},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018JG004622},\n\tkeywords = {\\#nosource, carbon cycle, carbon dioxide, emissions, ice-covered lake, methane, winter limnology},\n\tpages = {2527--2540},\n}\n\n\n\n\n\n In seasonally ice-covered lakes, carbon dioxide (CO2) and methane (CH4) emission at ice-off can account for a significant fraction of the annual budget. Yet knowledge of the mechanisms controlling below lake-ice carbon (C) dynamics and subsequent CO2 and CH4 emissions at ice-off is limited. To understand the control of below ice C dynamics, and C emissions in spring, we measured spatial variation in CO2, CH4, and dissolved inorganic and organic carbon from ice-on to ice-off, in a small boreal lake during a winter with sporadic melting events. Winter melt events were associated with decreased surface water DOC in the forest-dominated basin and increased surface water CH4 in the mire-dominated basin. At the whole-lake scale, CH4 accumulated below ice throughout the winter, whereas CO2 accumulation was greatest in early winter. Mass-balance estimates suggest that, in addition to the CO2 and CH4 accumulated during winter, external inputs of CO2 and CH4 and internal processing during ice-melt could represent significant sources of C gas emissions during ice-off. Moreover, internal processing of CO2 and CH4 worked in opposition, with production of CO2 and oxidation of CH4 dominating at ice-off. These findings have important implications for how small boreal lakes will respond to warmer winters in the future; increased winter melt events will likely increase external inputs below ice and thus alter the extent and timing of CO2 and CH4 emissions to the atmosphere at ice-off.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Global Food-Energy-Water Nexus.\n \n \n \n \n\n\n \n D'Odorico, P.; Davis, K. F.; Rosa, L.; Carr, J. A.; Chiarelli, D.; Dell'Angelo, J.; Gephart, J.; MacDonald, G. K.; Seekell, D. A.; Suweis, S.; and Rulli, M. C.\n\n\n \n\n\n\n Reviews of Geophysics, 56(3): 456–531. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2017RG000591\n\n\n\n
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\n\n\n@article{dodorico_global_2018,\n\ttitle = {The {Global} {Food}-{Energy}-{Water} {Nexus}},\n\tvolume = {56},\n\tcopyright = {©2018. The Authors.},\n\tissn = {1944-9208},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2017RG000591},\n\tdoi = {10.1029/2017RG000591},\n\tabstract = {Water availability is a major factor constraining humanity's ability to meet the future food and energy needs of a growing and increasingly affluent human population. Water plays an important role in the production of energy, including renewable energy sources and the extraction of unconventional fossil fuels that are expected to become important players in future energy security. The emergent competition for water between the food and energy systems is increasingly recognized in the concept of the “food-energy-water nexus.” The nexus between food and water is made even more complex by the globalization of agriculture and rapid growth in food trade, which results in a massive virtual transfer of water among regions and plays an important role in the food and water security of some regions. This review explores multiple components of the food-energy-water nexus and highlights possible approaches that could be used to meet food and energy security with the limited renewable water resources of the planet. Despite clear tensions inherent in meeting the growing and changing demand for food and energy in the 21st century, the inherent linkages among food, water, and energy systems can offer an opportunity for synergistic strategies aimed at resilient food, water, and energy security, such as the circular economy.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Reviews of Geophysics},\n\tauthor = {D'Odorico, Paolo and Davis, Kyle Frankel and Rosa, Lorenzo and Carr, Joel A. and Chiarelli, Davide and Dell'Angelo, Jampel and Gephart, Jessica and MacDonald, Graham K. and Seekell, David A. and Suweis, Samir and Rulli, Maria Cristina},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2017RG000591},\n\tkeywords = {\\#nosource, Circular Economy, FEW Nexus, Food Security, Food-water nexus, Water Security, Water Sustainability},\n\tpages = {456--531},\n}\n\n\n\n\n\n Water availability is a major factor constraining humanity's ability to meet the future food and energy needs of a growing and increasingly affluent human population. Water plays an important role in the production of energy, including renewable energy sources and the extraction of unconventional fossil fuels that are expected to become important players in future energy security. The emergent competition for water between the food and energy systems is increasingly recognized in the concept of the “food-energy-water nexus.” The nexus between food and water is made even more complex by the globalization of agriculture and rapid growth in food trade, which results in a massive virtual transfer of water among regions and plays an important role in the food and water security of some regions. This review explores multiple components of the food-energy-water nexus and highlights possible approaches that could be used to meet food and energy security with the limited renewable water resources of the planet. Despite clear tensions inherent in meeting the growing and changing demand for food and energy in the 21st century, the inherent linkages among food, water, and energy systems can offer an opportunity for synergistic strategies aimed at resilient food, water, and energy security, such as the circular economy.\n
\n\n\n\n \n\n \n \n \n \n \n \n The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems: A latitudinal study across Europe.\n \n \n \n \n\n\n \n Bravo, A. G.; Kothawala, D. N.; Attermeyer, K.; Tessier, E.; Bodmer, P.; Ledesma, J. L. J.; Audet, J.; Casas-Ruiz, J. P.; Catalán, N.; Cauvy-Fraunié, S.; Colls, M.; Deininger, A.; Evtimova, V. V.; Fonvielle, J. A.; Fuß, T.; Gilbert, P.; Herrero Ortega, S.; Liu, L.; Mendoza-Lera, C.; Monteiro, J.; Mor, J.; Nagler, M.; Niedrist, G. H.; Nydahl, A. C.; Pastor, A.; Pegg, J.; Gutmann Roberts, C.; Pilotto, F.; Portela, A. P.; González-Quijano, C. R.; Romero, F.; Rulík, M.; and Amouroux, D.\n\n\n \n\n\n\n Water Research, 144: 172–182. November 2018.\n \n\n\n\n
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\n\n\n@article{bravo_interplay_2018,\n\ttitle = {The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems: {A} latitudinal study across {Europe}},\n\tvolume = {144},\n\tissn = {0043-1354},\n\tshorttitle = {The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0043135418305244},\n\tdoi = {10.1016/j.watres.2018.06.064},\n\tabstract = {Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (\\%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06–2.78 ng L−1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8–159 pg L−1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive \\%MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.},\n\turldate = {2024-03-26},\n\tjournal = {Water Research},\n\tauthor = {Bravo, Andrea G. and Kothawala, Dolly N. and Attermeyer, Katrin and Tessier, Emmanuel and Bodmer, Pascal and Ledesma, José L. J. and Audet, Joachim and Casas-Ruiz, Joan Pere and Catalán, Núria and Cauvy-Fraunié, Sophie and Colls, Miriam and Deininger, Anne and Evtimova, Vesela V. and Fonvielle, Jérémy A. and Fuß, Thomas and Gilbert, Peter and Herrero Ortega, Sonia and Liu, Liu and Mendoza-Lera, Clara and Monteiro, Juliana and Mor, Jordi-René and Nagler, Magdalena and Niedrist, Georg H. and Nydahl, Anna C. and Pastor, Ada and Pegg, Josephine and Gutmann Roberts, Catherine and Pilotto, Francesca and Portela, Ana Paula and González-Quijano, Clara Romero and Romero, Ferran and Rulík, Martin and Amouroux, David},\n\tmonth = nov,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Fluorescence, Mercury, Methylmercury, Organic matter, Rivers, Streams},\n\tpages = {172--182},\n}\n\n\n\n\n\n Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06–2.78 ng L−1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8–159 pg L−1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Role of climate and herbivory on native and alien conifer seedling recruitment at and above the Fennoscandian tree line.\n \n \n \n \n\n\n \n Bognounou, F.; Hulme, P. E.; Oksanen, L.; Suominen, O.; and Olofsson, J.\n\n\n \n\n\n\n Journal of Vegetation Science, 29(4): 573–584. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.12637\n\n\n\n
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\n\n\n@article{bognounou_role_2018,\n\ttitle = {Role of climate and herbivory on native and alien conifer seedling recruitment at and above the {Fennoscandian} tree line},\n\tvolume = {29},\n\tcopyright = {© 2018 International Association for Vegetation Science},\n\tissn = {1654-1103},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.12637},\n\tdoi = {10.1111/jvs.12637},\n\tabstract = {Questions We investigated the importance of climate and herbivory on native and alien conifer colonization of the birch-dominated Fennoscandian tree line by addressing the following questions: (a) are tree line and tundra habitats similarly suitable for conifer seedling recruitment; (b) do ungulate and rodent herbivores differentially impact seedling recruitment; and (c) how does the role of habitat and herbivory on seedling recruitment vary across a marked climate gradient? Location Northern Fennoscandia, Sweden (Vassijaure and Paddus), and Norway (Joatka and Seiland). Methods We conducted an experiment to assess the emergence rate, survival probability and height development of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and Siberian larch (Larix sibirica) seedlings. Three experimental plots (i.e., open control, reindeer exclosure and complete vertebrate exclosure) were established in both tree line and tundra habitats at each of the four locations. Seeds of the three conifer species were sown in each plot in June 1999 during three consecutive years. The surviving seedlings were counted in August to September 1999, 2000, 2001, 2002 and 2007. The height of all seedlings was measured in 2007. Results Our study reveals that Norway spruce, Scots pine and Siberian larch can regenerate from seed at and above the current tree line in northern Fennoscandia. Their performance was generally higher above tree line in tundra than at tree line, but depended on species identity, climate aridity and mammal herbivory, particularly by rodents. These results suggest that the species composition and latitudinal limit of the tree line in the future might depend not only on direct effects of the future climate on the current tree line species, but also on the intensity of alien and native conifer introductions, as well as changes in herbivore populations. Conclusion If sufficient seeds of Norway spruce, Scots pine and Siberian larch should reach the current tree line, their performances will increase with a warmer and wetter climate, and this effect will be markedly modulated by herbivores (particularly rodents). Further work is required to extend these results to determine the ability of these conifers to become tree line-forming species in the future.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-26},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Bognounou, Fidele and Hulme, Philip E. and Oksanen, Lauri and Suominen, Otso and Olofsson, Johan},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jvs.12637},\n\tkeywords = {\\#nosource, biological invasions, conifer, exclosures, lemmings, propagule pressure, reindeer, seedling recruitment, seedling survival, tundra, vole},\n\tpages = {573--584},\n}\n\n\n\n\n\n Questions We investigated the importance of climate and herbivory on native and alien conifer colonization of the birch-dominated Fennoscandian tree line by addressing the following questions: (a) are tree line and tundra habitats similarly suitable for conifer seedling recruitment; (b) do ungulate and rodent herbivores differentially impact seedling recruitment; and (c) how does the role of habitat and herbivory on seedling recruitment vary across a marked climate gradient? Location Northern Fennoscandia, Sweden (Vassijaure and Paddus), and Norway (Joatka and Seiland). Methods We conducted an experiment to assess the emergence rate, survival probability and height development of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and Siberian larch (Larix sibirica) seedlings. Three experimental plots (i.e., open control, reindeer exclosure and complete vertebrate exclosure) were established in both tree line and tundra habitats at each of the four locations. Seeds of the three conifer species were sown in each plot in June 1999 during three consecutive years. The surviving seedlings were counted in August to September 1999, 2000, 2001, 2002 and 2007. The height of all seedlings was measured in 2007. Results Our study reveals that Norway spruce, Scots pine and Siberian larch can regenerate from seed at and above the current tree line in northern Fennoscandia. Their performance was generally higher above tree line in tundra than at tree line, but depended on species identity, climate aridity and mammal herbivory, particularly by rodents. These results suggest that the species composition and latitudinal limit of the tree line in the future might depend not only on direct effects of the future climate on the current tree line species, but also on the intensity of alien and native conifer introductions, as well as changes in herbivore populations. Conclusion If sufficient seeds of Norway spruce, Scots pine and Siberian larch should reach the current tree line, their performances will increase with a warmer and wetter climate, and this effect will be markedly modulated by herbivores (particularly rodents). Further work is required to extend these results to determine the ability of these conifers to become tree line-forming species in the future.\n
\n\n\n\n \n\n \n \n \n \n \n \n Tundra Trait Team: A database of plant traits spanning the tundra biome.\n \n \n \n \n\n\n \n Bjorkman, A. D.; Myers-Smith, I. H.; Elmendorf, S. C.; Normand, S.; Thomas, H. J. D.; Alatalo, J. M.; Alexander, H.; Anadon-Rosell, A.; Angers-Blondin, S.; Bai, Y.; Baruah, G.; te Beest, M.; Berner, L.; Björk, R. G.; Blok, D.; Bruelheide, H.; Buchwal, A.; Buras, A.; Carbognani, M.; Christie, K.; Collier, L. S.; Cooper, E. J.; Cornelissen, J. H. C.; Dickinson, K. J. M.; Dullinger, S.; Elberling, B.; Eskelinen, A.; Forbes, B. C.; Frei, E. R.; Iturrate-Garcia, M.; Good, M. K.; Grau, O.; Green, P.; Greve, M.; Grogan, P.; Haider, S.; Hájek, T.; Hallinger, M.; Happonen, K.; Harper, K. A.; Heijmans, M. M. P. D.; Henry, G. H. R.; Hermanutz, L.; Hewitt, R. E.; Hollister, R. D.; Hudson, J.; Hülber, K.; Iversen, C. M.; Jaroszynska, F.; Jiménez-Alfaro, B.; Johnstone, J.; Jorgensen, R. H.; Kaarlejärvi, E.; Klady, R.; Klimešová, J.; Korsten, A.; Kuleza, S.; Kulonen, A.; Lamarque, L. J.; Lantz, T.; Lavalle, A.; Lembrechts, J. J.; Lévesque, E.; Little, C. J.; Luoto, M.; Macek, P.; Mack, M. C.; Mathakutha, R.; Michelsen, A.; Milbau, A.; Molau, U.; Morgan, J. W.; Mörsdorf, M. A.; Nabe-Nielsen, J.; Nielsen, S. S.; Ninot, J. M.; Oberbauer, S. F.; Olofsson, J.; Onipchenko, V. G.; Petraglia, A.; Pickering, C.; Prevéy, J. S.; Rixen, C.; Rumpf, S. B.; Schaepman-Strub, G.; Semenchuk, P.; Shetti, R.; Soudzilovskaia, N. A.; Spasojevic, M. J.; Speed, J. D. M.; Street, L. E.; Suding, K.; Tape, K. D.; Tomaselli, M.; Trant, A.; Treier, U. A.; Tremblay, J.; Tremblay, M.; Venn, S.; Virkkala, A.; Vowles, T.; Weijers, S.; Wilmking, M.; Wipf, S.; and Zamin, T.\n\n\n \n\n\n\n Global Ecology and Biogeography, 27(12): 1402–1411. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/geb.12821\n\n\n\n
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\n\n\n@article{bjorkman_tundra_2018,\n\ttitle = {Tundra {Trait} {Team}: {A} database of plant traits spanning the tundra biome},\n\tvolume = {27},\n\tcopyright = {© 2018 The Authors Global Ecology and Biogeography Published by John Wiley \\& Sons Ltd},\n\tissn = {1466-8238},\n\tshorttitle = {Tundra {Trait} {Team}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12821},\n\tdoi = {10.1111/geb.12821},\n\tabstract = {Motivation The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits ({\\textgreater} 1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99\\% of observations are georeferenced. Time period and grain All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86\\%), while the remainder represent plot or site means or maximums per species. Software format csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2024-03-26},\n\tjournal = {Global Ecology and Biogeography},\n\tauthor = {Bjorkman, Anne D. and Myers-Smith, Isla H. and Elmendorf, Sarah C. and Normand, Signe and Thomas, Haydn J. D. and Alatalo, Juha M. and Alexander, Heather and Anadon-Rosell, Alba and Angers-Blondin, Sandra and Bai, Yang and Baruah, Gaurav and te Beest, Mariska and Berner, Logan and Björk, Robert G. and Blok, Daan and Bruelheide, Helge and Buchwal, Agata and Buras, Allan and Carbognani, Michele and Christie, Katherine and Collier, Laura S. and Cooper, Elisabeth J. and Cornelissen, J. Hans C. and Dickinson, Katharine J. M. and Dullinger, Stefan and Elberling, Bo and Eskelinen, Anu and Forbes, Bruce C. and Frei, Esther R. and Iturrate-Garcia, Maitane and Good, Megan K. and Grau, Oriol and Green, Peter and Greve, Michelle and Grogan, Paul and Haider, Sylvia and Hájek, Tomáš and Hallinger, Martin and Happonen, Konsta and Harper, Karen A. and Heijmans, Monique M. P. D. and Henry, Gregory H. R. and Hermanutz, Luise and Hewitt, Rebecca E. and Hollister, Robert D. and Hudson, James and Hülber, Karl and Iversen, Colleen M. and Jaroszynska, Francesca and Jiménez-Alfaro, Borja and Johnstone, Jill and Jorgensen, Rasmus Halfdan and Kaarlejärvi, Elina and Klady, Rebecca and Klimešová, Jitka and Korsten, Annika and Kuleza, Sara and Kulonen, Aino and Lamarque, Laurent J. and Lantz, Trevor and Lavalle, Amanda and Lembrechts, Jonas J. and Lévesque, Esther and Little, Chelsea J. and Luoto, Miska and Macek, Petr and Mack, Michelle C. and Mathakutha, Rabia and Michelsen, Anders and Milbau, Ann and Molau, Ulf and Morgan, John W. and Mörsdorf, Martin Alfons and Nabe-Nielsen, Jacob and Nielsen, Sigrid Schøler and Ninot, Josep M. and Oberbauer, Steven F. and Olofsson, Johan and Onipchenko, Vladimir G. and Petraglia, Alessandro and Pickering, Catherine and Prevéy, Janet S. and Rixen, Christian and Rumpf, Sabine B. and Schaepman-Strub, Gabriela and Semenchuk, Philipp and Shetti, Rohan and Soudzilovskaia, Nadejda A. and Spasojevic, Marko J. and Speed, James David Mervyn and Street, Lorna E. and Suding, Katharine and Tape, Ken D. and Tomaselli, Marcello and Trant, Andrew and Treier, Urs A. and Tremblay, Jean-Pierre and Tremblay, Maxime and Venn, Susanna and Virkkala, Anna-Maria and Vowles, Tage and Weijers, Stef and Wilmking, Martin and Wipf, Sonja and Zamin, Tara},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/geb.12821},\n\tkeywords = {\\#nosource, Arctic, alpine, plant functional traits, tundra},\n\tpages = {1402--1411},\n}\n\n\n\n\n\n Motivation The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (\\textgreater 1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.\n
\n\n\n\n \n\n \n \n \n \n \n \n High Grazing Pressure of Geese Threatens Conservation and Restoration of Reed Belts.\n \n \n \n \n\n\n \n Bakker, E. S.; Veen, C. G. F.; Ter Heerdt, G. J. N.; Huig, N.; and Sarneel, J. M.\n\n\n \n\n\n\n Frontiers in Plant Science, 9: 1649. November 2018.\n Publisher: Frontiers\n\n\n\n
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\n\n\n@article{bakker_high_2018,\n\ttitle = {High {Grazing} {Pressure} of {Geese} {Threatens} {Conservation} and {Restoration} of {Reed} {Belts}},\n\tvolume = {9},\n\tissn = {1664-462X},\n\turl = {https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01649/full},\n\tdoi = {10.3389/fpls.2018.01649},\n\tabstract = {Reed (Phragmites australis Cav.) Trin. ex Steud.) beds are important habitat for marsh birds, but are declining throughout Europe. Increasing numbers of the native marsh bird, the Greylag goose ({\\textless}italic{\\textgreater}Anser anser{\\textless}/italic{\\textgreater} L.), are hypothesized to cause reed bed decline and inhibit restoration of reed beds, but data are largely lacking. In this study, we experimentally tested the effect of grazing by Greylag geese on the growth and expansion of reed growing in belts along lake shorelines. After 5 years of protecting reed from grazing with exclosures, reed stems were over 4-fold denser and taller than in the grazed plots. Grazing pressure was intense with 50–100\\% of the stems being grazed among years in the control plots open to grazing. After 5 years of protection we opened half of the exclosures and the geese immediately grazed almost 100\\% of the reed stems. Whereas this did not affect the reed stem density, the stem height was strongly reduced and similar to permanently grazed reed. The next year geese were actively chased away by management from mid-March to mid-June, which changed the maximum amount of geese from over 2300 to less than 50. As a result, reed stem density and height increased and the reed belt had recovered over the full 6 m length of the experimental plots. Lastly, we introduced reed plants in an adjacent lake where no reed was growing and geese did visit this area. After two years, the density of the planted reed was six to nine-fold higher and significantly taller in exclosures compared to control plots where geese had access to the reed plants. We conclude that there is a conservation dilemma regarding how to preserve and restore reed belts in the presence of high densities of Greylag geese as conservation of both reed belts and high goose numbers seems infeasible. We suggest that there are three possible solutions for this dilemma: (1) effects of the geese can be mediated by goose population management, (2) the robustness of the reed marshes can be increased, and (3) at the landscape level, spatial planning can be used to configure landscapes with large reed bed reserves surrounded by unmown, unfertilized meadows.},\n\tlanguage = {English},\n\turldate = {2024-03-26},\n\tjournal = {Frontiers in Plant Science},\n\tauthor = {Bakker, Elisabeth S. and Veen, Ciska G. F. and Ter Heerdt, Gerard J. N. and Huig, Naomi and Sarneel, Judith M.},\n\tmonth = nov,\n\tyear = {2018},\n\tnote = {Publisher: Frontiers},\n\tkeywords = {Anser anser, Aquatic plant, Exclosure, Herbivory, Landscape configuration, Phragmites australis, restoration, wetland},\n\tpages = {1649},\n}\n\n\n\n\n\n Reed (Phragmites australis Cav.) Trin. ex Steud.) beds are important habitat for marsh birds, but are declining throughout Europe. Increasing numbers of the native marsh bird, the Greylag goose (\\textlessitalic\\textgreaterAnser anser\\textless/italic\\textgreater L.), are hypothesized to cause reed bed decline and inhibit restoration of reed beds, but data are largely lacking. In this study, we experimentally tested the effect of grazing by Greylag geese on the growth and expansion of reed growing in belts along lake shorelines. After 5 years of protecting reed from grazing with exclosures, reed stems were over 4-fold denser and taller than in the grazed plots. Grazing pressure was intense with 50–100% of the stems being grazed among years in the control plots open to grazing. After 5 years of protection we opened half of the exclosures and the geese immediately grazed almost 100% of the reed stems. Whereas this did not affect the reed stem density, the stem height was strongly reduced and similar to permanently grazed reed. The next year geese were actively chased away by management from mid-March to mid-June, which changed the maximum amount of geese from over 2300 to less than 50. As a result, reed stem density and height increased and the reed belt had recovered over the full 6 m length of the experimental plots. Lastly, we introduced reed plants in an adjacent lake where no reed was growing and geese did visit this area. After two years, the density of the planted reed was six to nine-fold higher and significantly taller in exclosures compared to control plots where geese had access to the reed plants. We conclude that there is a conservation dilemma regarding how to preserve and restore reed belts in the presence of high densities of Greylag geese as conservation of both reed belts and high goose numbers seems infeasible. We suggest that there are three possible solutions for this dilemma: (1) effects of the geese can be mediated by goose population management, (2) the robustness of the reed marshes can be increased, and (3) at the landscape level, spatial planning can be used to configure landscapes with large reed bed reserves surrounded by unmown, unfertilized meadows.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lags in the response of mountain plant communities to climate change.\n \n \n \n \n\n\n \n Alexander, J. M.; Chalmandrier, L.; Lenoir, J.; Burgess, T. I.; Essl, F.; Haider, S.; Kueffer, C.; McDougall, K.; Milbau, A.; Nuñez, M. A.; Pauchard, A.; Rabitsch, W.; Rew, L. J.; Sanders, N. J.; and Pellissier, L.\n\n\n \n\n\n\n Global Change Biology, 24(2): 563–579. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13976\n\n\n\n
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\n\n\n@article{alexander_lags_2018,\n\ttitle = {Lags in the response of mountain plant communities to climate change},\n\tvolume = {24},\n\tcopyright = {© 2017 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13976},\n\tdoi = {10.1111/gcb.13976},\n\tabstract = {Rapid climatic changes and increasing human influence at high elevations around the world will have profound impacts on mountain biodiversity. However, forecasts from statistical models (e.g. species distribution models) rarely consider that plant community changes could substantially lag behind climatic changes, hindering our ability to make temporally realistic projections for the coming century. Indeed, the magnitudes of lags, and the relative importance of the different factors giving rise to them, remain poorly understood. We review evidence for three types of lag: “dispersal lags” affecting plant species’ spread along elevational gradients, “establishment lags” following their arrival in recipient communities, and “extinction lags” of resident species. Variation in lags is explained by variation among species in physiological and demographic responses, by effects of altered biotic interactions, and by aspects of the physical environment. Of these, altered biotic interactions could contribute substantially to establishment and extinction lags, yet impacts of biotic interactions on range dynamics are poorly understood. We develop a mechanistic community model to illustrate how species turnover in future communities might lag behind simple expectations based on species’ range shifts with unlimited dispersal. The model shows a combined contribution of altered biotic interactions and dispersal lags to plant community turnover along an elevational gradient following climate warming. Our review and simulation support the view that accounting for disequilibrium range dynamics will be essential for realistic forecasts of patterns of biodiversity under climate change, with implications for the conservation of mountain species and the ecosystem functions they provide.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Global Change Biology},\n\tauthor = {Alexander, Jake M. and Chalmandrier, Loïc and Lenoir, Jonathan and Burgess, Treena I. and Essl, Franz and Haider, Sylvia and Kueffer, Christoph and McDougall, Keith and Milbau, Ann and Nuñez, Martin A. and Pauchard, Aníbal and Rabitsch, Wolfgang and Rew, Lisa J. and Sanders, Nathan J. and Pellissier, Loïc},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13976},\n\tkeywords = {\\#nosource, alpine ecosystems, biotic interactions, climate change, climatic debt, migration, novel interactions, range dynamics, range expansion},\n\tpages = {563--579},\n}\n\n\n\n\n\n Rapid climatic changes and increasing human influence at high elevations around the world will have profound impacts on mountain biodiversity. However, forecasts from statistical models (e.g. species distribution models) rarely consider that plant community changes could substantially lag behind climatic changes, hindering our ability to make temporally realistic projections for the coming century. Indeed, the magnitudes of lags, and the relative importance of the different factors giving rise to them, remain poorly understood. We review evidence for three types of lag: “dispersal lags” affecting plant species’ spread along elevational gradients, “establishment lags” following their arrival in recipient communities, and “extinction lags” of resident species. Variation in lags is explained by variation among species in physiological and demographic responses, by effects of altered biotic interactions, and by aspects of the physical environment. Of these, altered biotic interactions could contribute substantially to establishment and extinction lags, yet impacts of biotic interactions on range dynamics are poorly understood. We develop a mechanistic community model to illustrate how species turnover in future communities might lag behind simple expectations based on species’ range shifts with unlimited dispersal. The model shows a combined contribution of altered biotic interactions and dispersal lags to plant community turnover along an elevational gradient following climate warming. Our review and simulation support the view that accounting for disequilibrium range dynamics will be essential for realistic forecasts of patterns of biodiversity under climate change, with implications for the conservation of mountain species and the ecosystem functions they provide.\n
\n\n\n\n \n\n \n \n \n \n \n \n Permafrost and lakes control river isotope composition across a boreal Arctic transect in the Western Siberian lowlands.\n \n \n \n \n\n\n \n Ala-aho, P.; Soulsby, C.; Pokrovsky, O. S.; Kirpotin, S. N.; Karlsson, J.; Serikova, S.; Manasypov, R.; Lim, A.; Krickov, I.; Kolesnichenko, L. G.; Laudon, H.; and Tetzlaff, D.\n\n\n \n\n\n\n Environmental Research Letters, 13(3): 034028. February 2018.\n Publisher: IOP Publishing\n\n\n\n
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\n\n\n@article{ala-aho_permafrost_2018,\n\ttitle = {Permafrost and lakes control river isotope composition across a boreal {Arctic} transect in the {Western} {Siberian} lowlands},\n\tvolume = {13},\n\tissn = {1748-9326},\n\turl = {https://dx.doi.org/10.1088/1748-9326/aaa4fe},\n\tdoi = {10.1088/1748-9326/aaa4fe},\n\tabstract = {The Western Siberian Lowlands (WSL) store large quantities of organic carbon that will be exposed and mobilized by the thawing of permafrost. The fate of mobilized carbon, however, is not well understood, partly because of inadequate knowledge of hydrological controls in the region which has a vast low-relief surface area, extensive lake and wetland coverage and gradually increasing permafrost influence. We used stable water isotopes to improve our understanding of dominant landscape controls on the hydrology of the WSL. We sampled rivers along a 1700 km South–North transect from permafrost-free to continuous permafrost repeatedly over three years, and derived isotope proxies for catchment hydrological responsiveness and connectivity. We found correlations between the isotope proxies and catchment characteristics, suggesting that lakes and wetlands are intimately connected to rivers, and that permafrost increases the responsiveness of the catchment to rainfall and snowmelt events, reducing catchment mean transit times. Our work provides rare isotope-based field evidence that permafrost and lakes/wetlands influence hydrological pathways across a wide range of spatial scales (10–105 km2) and permafrost coverage (0\\%–70\\%). This has important implications, because both permafrost extent and lake/wetland coverage are affected by permafrost thaw in the changing climate. Changes in these hydrological landscape controls are likely to alter carbon export and emission via inland waters, which may be of global significance.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-26},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Ala-aho, P. and Soulsby, C. and Pokrovsky, O. S. and Kirpotin, S. N. and Karlsson, J. and Serikova, S. and Manasypov, R. and Lim, A. and Krickov, I. and Kolesnichenko, L. G. and Laudon, H. and Tetzlaff, D.},\n\tmonth = feb,\n\tyear = {2018},\n\tnote = {Publisher: IOP Publishing},\n\tkeywords = {\\#nosource},\n\tpages = {034028},\n}\n\n\n\n\n\n The Western Siberian Lowlands (WSL) store large quantities of organic carbon that will be exposed and mobilized by the thawing of permafrost. The fate of mobilized carbon, however, is not well understood, partly because of inadequate knowledge of hydrological controls in the region which has a vast low-relief surface area, extensive lake and wetland coverage and gradually increasing permafrost influence. We used stable water isotopes to improve our understanding of dominant landscape controls on the hydrology of the WSL. We sampled rivers along a 1700 km South–North transect from permafrost-free to continuous permafrost repeatedly over three years, and derived isotope proxies for catchment hydrological responsiveness and connectivity. We found correlations between the isotope proxies and catchment characteristics, suggesting that lakes and wetlands are intimately connected to rivers, and that permafrost increases the responsiveness of the catchment to rainfall and snowmelt events, reducing catchment mean transit times. Our work provides rare isotope-based field evidence that permafrost and lakes/wetlands influence hydrological pathways across a wide range of spatial scales (10–105 km2) and permafrost coverage (0%–70%). This has important implications, because both permafrost extent and lake/wetland coverage are affected by permafrost thaw in the changing climate. Changes in these hydrological landscape controls are likely to alter carbon export and emission via inland waters, which may be of global significance.\n
\n\n\n\n \n\n \n \n \n \n \n \n The sedimentary and remote-sensing reflection of biomass burning in Europe.\n \n \n \n \n\n\n \n Adolf, C.; Wunderle, S.; Colombaroli, D.; Weber, H.; Gobet, E.; Heiri, O.; van Leeuwen, J. F. N.; Bigler, C.; Connor, S. E.; Gałka, M.; La Mantia, T.; Makhortykh, S.; Svitavská-Svobodová, H.; Vannière, B.; and Tinner, W.\n\n\n \n\n\n\n Global Ecology and Biogeography, 27(2): 199–212. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/geb.12682\n\n\n\n
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\n\n\n@article{adolf_sedimentary_2018,\n\ttitle = {The sedimentary and remote-sensing reflection of biomass burning in {Europe}},\n\tvolume = {27},\n\tcopyright = {© 2017 John Wiley \\& Sons Ltd},\n\tissn = {1466-8238},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12682},\n\tdoi = {10.1111/geb.12682},\n\tabstract = {Aim We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10–500 µm) and macroscopic charcoal (MAC from sieves, particles {\\textgreater} 100 µm). Location North–south and east–west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period Lake sediments and MODIS active fire and burned area products were collected for the years 2012–2015. Methods Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm2/year) and the MODIS-derived products to identify source areas of charcoal and the extent to which lake-sediment charcoal is linked to fire parameters across the continent. Results Source area of sedimentary charcoal was estimated to a 40-km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel-type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS-derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles ({\\textgreater} 600 µm), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2024-03-26},\n\tjournal = {Global Ecology and Biogeography},\n\tauthor = {Adolf, Carole and Wunderle, Stefan and Colombaroli, Daniele and Weber, Helga and Gobet, Erika and Heiri, Oliver and van Leeuwen, Jacqueline F. N. and Bigler, Christian and Connor, Simon E. and Gałka, Mariusz and La Mantia, Tommaso and Makhortykh, Sergey and Svitavská-Svobodová, Helena and Vannière, Boris and Tinner, Willy},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/geb.12682},\n\tkeywords = {\\#nosource, MODIS, calibration in space, fire ecology, fire regime, lake-sediment charcoal, palaeoecology},\n\tpages = {199--212},\n}\n\n\n\n\n\n Aim We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10–500 µm) and macroscopic charcoal (MAC from sieves, particles \\textgreater 100 µm). Location North–south and east–west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period Lake sediments and MODIS active fire and burned area products were collected for the years 2012–2015. Methods Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm2/year) and the MODIS-derived products to identify source areas of charcoal and the extent to which lake-sediment charcoal is linked to fire parameters across the continent. Results Source area of sedimentary charcoal was estimated to a 40-km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel-type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS-derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles (\\textgreater 600 µm), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.\n
\n\n\n\n \n\n \n \n \n \n \n \n Environmental and taxonomic controls of carbon and oxygen stable isotope composition in Sphagnum across broad climatic and geographic ranges.\n \n \n \n \n\n\n \n Granath, G.; Rydin, H.; Baltzer, J. L.; Bengtsson, F.; Boncek, N.; Bragazza, L.; Bu, Z.; Caporn, S. J. M.; Dorrepaal, E.; Galanina, O.; Gałka, M.; Ganeva, A.; Gillikin, D. P.; Goia, I.; Goncharova, N.; Hájek, M.; Haraguchi, A.; Harris, L. I.; Humphreys, E.; Jiroušek, M.; Kajukało, K.; Karofeld, E.; Koronatova, N. G.; Kosykh, N. P.; Lamentowicz, M.; Lapshina, E.; Limpens, J.; Linkosalmi, M.; Ma, J.; Mauritz, M.; Munir, T. M.; Natali, S. M.; Natcheva, R.; Noskova, M.; Payne, R. J.; Pilkington, K.; Robinson, S.; Robroek, B. J. M.; Rochefort, L.; Singer, D.; Stenøien, H. K.; Tuittila, E.; Vellak, K.; Verheyden, A.; Waddington, J. M.; and Rice, S. K.\n\n\n \n\n\n\n Biogeosciences, 15(16): 5189–5202. August 2018.\n 00000\n\n\n\n
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\n\n\n@article{granath_environmental_2018,\n\ttitle = {Environmental and taxonomic controls of carbon and oxygen stable isotope composition in \\textit{{Sphagnum}} across broad climatic and geographic ranges},\n\tvolume = {15},\n\tissn = {1726-4170},\n\turl = {https://www.biogeosciences.net/15/5189/2018/bg-15-5189-2018.html},\n\tdoi = {10.5194/bg-15-5189-2018},\n\tabstract = {{\\textless}p{\\textgreater}{\\textless}strong{\\textgreater}Abstract.{\\textless}/strong{\\textgreater} Rain-fed peatlands are dominated by peat mosses (\\textit{Sphagnum} sp.), which for their growth depend on nutrients, water and CO$_{\\textrm{2}}$ uptake from the atmosphere. As the isotopic composition of carbon ($^{\\textrm{12,13}}$C) and oxygen ($^{\\textrm{16,18}}$O) of these \\textit{Sphagnum} mosses are affected by environmental conditions, \\textit{Sphagnum} tissue accumulated in peat constitutes a potential long-term archive that can be used for climate reconstruction. However, there is inadequate understanding of how isotope values are influenced by environmental conditions, which restricts their current use as environmental and palaeoenvironmental indicators. Here we tested (i) to what extent C and O isotopic variation in living tissue of \\textit{Sphagnum} is species-specific and associated with local hydrological gradients, climatic gradients (evapotranspiration, temperature, precipitation) and elevation; (ii) whether the C isotopic signature can be a proxy for net primary productivity (NPP) of \\textit{Sphagnum}; and (iii) to what extent \\textit{Sphagnum} tissue \\textit{δ}$^{\\textrm{18}}$O tracks the \\textit{δ}$^{\\textrm{18}}$O isotope signature of precipitation. In total, we analysed 337 samples from 93 sites across North America and Eurasia using two important peat-forming \\textit{Sphagnum }species (\\textit{S. magellanicum}, \\textit{S. fuscum}) common to the Holarctic realm. There were differences in \\textit{δ}$^{\\textrm{13}}$C values between species. For \\textit{S. magellanicum} \\textit{δ}$^{\\textrm{13}}$C decreased with increasing height above the water table (HWT, \\textit{R}$^{\\textrm{2}}$ = 17{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\%) and was positively correlated to productivity (\\textit{R}$^{\\textrm{2}}$ = 7{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\%). Together these two variables explained 46{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\% of the between-site variation in \\textit{δ}$^{\\textrm{13}}$C values. For \\textit{S. fuscum}, productivity was the only significant predictor of \\textit{δ}$^{\\textrm{13}}$C but had low explanatory power (total \\textit{R}$^{\\textrm{2}}$ = 6{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\%). For \\textit{δ}$^{\\textrm{18}}$O values, approximately 90{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\% of the variation was found between sites. Globally modelled annual \\textit{δ}$^{\\textrm{18}}$O values in precipitation explained 69{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\% of the between-site variation in tissue \\textit{δ}$^{\\textrm{18}}$O. \\textit{S. magellanicum} showed lower \\textit{δ}$^{\\textrm{18}}$O enrichment than \\textit{S. fuscum} (−0.83{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}‰ lower). Elevation and climatic variables were weak predictors of tissue \\textit{δ}$^{\\textrm{18}}$O values after controlling for \\textit{δ}$^{\\textrm{18}}$O values of the precipitation. To summarize, our study provides evidence for (a) good predictability of tissue \\textit{δ}$^{\\textrm{18}}$O values from modelled annual \\textit{δ}$^{\\textrm{18}}$O values in precipitation, and (b) the possibility of relating tissue \\textit{δ}$^{\\textrm{13}}$C values to HWT and NPP, but this appears to be species-dependent. These results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\tnumber = {16},\n\turldate = {2018-09-17},\n\tjournal = {Biogeosciences},\n\tauthor = {Granath, Gustaf and Rydin, Håkan and Baltzer, Jennifer L. and Bengtsson, Fia and Boncek, Nicholas and Bragazza, Luca and Bu, Zhao-Jun and Caporn, Simon J. M. and Dorrepaal, Ellen and Galanina, Olga and Gałka, Mariusz and Ganeva, Anna and Gillikin, David P. and Goia, Irina and Goncharova, Nadezhda and Hájek, Michal and Haraguchi, Akira and Harris, Lorna I. and Humphreys, Elyn and Jiroušek, Martin and Kajukało, Katarzyna and Karofeld, Edgar and Koronatova, Natalia G. and Kosykh, Natalia P. and Lamentowicz, Mariusz and Lapshina, Elena and Limpens, Juul and Linkosalmi, Maiju and Ma, Jin-Ze and Mauritz, Marguerite and Munir, Tariq M. and Natali, Susan M. and Natcheva, Rayna and Noskova, Maria and Payne, Richard J. and Pilkington, Kyle and Robinson, Sean and Robroek, Bjorn J. M. and Rochefort, Line and Singer, David and Stenøien, Hans K. and Tuittila, Eeva-Stiina and Vellak, Kai and Verheyden, Anouk and Waddington, James Michael and Rice, Steven K.},\n\tmonth = aug,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {5189--5202},\n}\n\n\n\n\n\n \\textlessp\\textgreater\\textlessstrong\\textgreaterAbstract.\\textless/strong\\textgreater Rain-fed peatlands are dominated by peat mosses (Sphagnum sp.), which for their growth depend on nutrients, water and CO$_{\\textrm{2}}$ uptake from the atmosphere. As the isotopic composition of carbon ($^{\\textrm{12,13}}$C) and oxygen ($^{\\textrm{16,18}}$O) of these Sphagnum mosses are affected by environmental conditions, Sphagnum tissue accumulated in peat constitutes a potential long-term archive that can be used for climate reconstruction. However, there is inadequate understanding of how isotope values are influenced by environmental conditions, which restricts their current use as environmental and palaeoenvironmental indicators. Here we tested (i) to what extent C and O isotopic variation in living tissue of Sphagnum is species-specific and associated with local hydrological gradients, climatic gradients (evapotranspiration, temperature, precipitation) and elevation; (ii) whether the C isotopic signature can be a proxy for net primary productivity (NPP) of Sphagnum; and (iii) to what extent Sphagnum tissue δ$^{\\textrm{18}}$O tracks the δ$^{\\textrm{18}}$O isotope signature of precipitation. In total, we analysed 337 samples from 93 sites across North America and Eurasia using two important peat-forming Sphagnum species (S. magellanicum, S. fuscum) common to the Holarctic realm. There were differences in δ$^{\\textrm{13}}$C values between species. For S. magellanicum δ$^{\\textrm{13}}$C decreased with increasing height above the water table (HWT, R$^{\\textrm{2}}$ = 17\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater%) and was positively correlated to productivity (R$^{\\textrm{2}}$ = 7\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater%). Together these two variables explained 46\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater% of the between-site variation in δ$^{\\textrm{13}}$C values. For S. fuscum, productivity was the only significant predictor of δ$^{\\textrm{13}}$C but had low explanatory power (total R$^{\\textrm{2}}$ = 6\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater%). For δ$^{\\textrm{18}}$O values, approximately 90\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater% of the variation was found between sites. Globally modelled annual δ$^{\\textrm{18}}$O values in precipitation explained 69\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater% of the between-site variation in tissue δ$^{\\textrm{18}}$O. S. magellanicum showed lower δ$^{\\textrm{18}}$O enrichment than S. fuscum (−0.83\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater‰ lower). Elevation and climatic variables were weak predictors of tissue δ$^{\\textrm{18}}$O values after controlling for δ$^{\\textrm{18}}$O values of the precipitation. To summarize, our study provides evidence for (a) good predictability of tissue δ$^{\\textrm{18}}$O values from modelled annual δ$^{\\textrm{18}}$O values in precipitation, and (b) the possibility of relating tissue δ$^{\\textrm{13}}$C values to HWT and NPP, but this appears to be species-dependent. These results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n Riverine particulate C and N generated at the permafrost thaw front: case study of western Siberian rivers across a 1700 km latitudinal transect.\n \n \n \n \n\n\n \n Krickov, I. V.; Lim, A. G.; Manasypov, R. M.; Loiko, S. V.; Shirokova, L. S.; Kirpotin, S. N.; Karlsson, J.; and Pokrovsky, O. S.\n\n\n \n\n\n\n Biogeosciences, 15(22): 6867–6884. November 2018.\n \n\n\n\n
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\n\n\n@article{krickov_riverine_2018,\n\ttitle = {Riverine particulate {C} and {N} generated at the permafrost thaw front: case study of western {Siberian} rivers across a 1700\\ km latitudinal transect},\n\tvolume = {15},\n\tissn = {1726-4170},\n\tshorttitle = {Riverine particulate {C} and {N} generated at the permafrost thaw front},\n\turl = {https://www.biogeosciences.net/15/6867/2018/},\n\tdoi = {10.5194/bg-15-6867-2018},\n\tabstract = {{\\textless}p{\\textgreater}{\\textless}strong{\\textgreater}Abstract.{\\textless}/strong{\\textgreater} In contrast to numerous studies on the dynamics of dissolved ( \\< 0.45{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}µm) elements in permafrost-affected high-latitude rivers, very little is known of the behavior of river suspended ( \\> 0.45{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}µm) matter (RSM) in these regions. In order to test the effect of climate, permafrost and physio-geographical landscape parameters (bogs, forest and lake coverage of the watershed) on RSM and particulate C, N and P concentrations in river water, we sampled 33 small and medium-sized rivers (10–100{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}000{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}km$^{\\textrm{2}}$ watershed) along a 1700{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}km N–S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL). The concentrations of C and N in RSM decreased with the increase in river watershed size, illustrating (i) the importance of organic debris in small rivers which drain peatlands and (ii) the role of mineral matter from bank abrasion in larger rivers. The presence of lakes in the watershed increased C and N but decreased P concentrations in the RSM. The C : N ratio in the RSM reflected the source from the deep soil horizon rather than surface soil horizon, similar to that of other Arctic rivers. This suggests the export of peat and mineral particles through suprapermafrost flow occurring at the base of the active layer. There was a maximum of both particulate C and N concentrations and export fluxes at the beginning of permafrost appearance, in the sporadic and discontinuous zone (62–64°{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}N). This presumably reflected the organic matter mobilization from newly thawed organic horizons in soils at the active latitudinal thawing front. The results suggest that a northward shift of permafrost boundaries and an increase in active layer thickness may increase particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2, while P export may remain unchanged. In contrast, within a long-term climate warming scenario, the disappearance of permafrost in the north, the drainage of lakes and transformation of bogs to forest may decrease C and N concentrations in RSM by 2 to 3 times.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\tnumber = {22},\n\turldate = {2018-11-27},\n\tjournal = {Biogeosciences},\n\tauthor = {Krickov, Ivan V. and Lim, Artem G. and Manasypov, Rinat M. and Loiko, Sergey V. and Shirokova, Liudmila S. and Kirpotin, Sergey N. and Karlsson, Jan and Pokrovsky, Oleg S.},\n\tmonth = nov,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {6867--6884},\n}\n\n\n\n\n\n \\textlessp\\textgreater\\textlessstrong\\textgreaterAbstract.\\textless/strong\\textgreater In contrast to numerous studies on the dynamics of dissolved ( < 0.45\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreaterµm) elements in permafrost-affected high-latitude rivers, very little is known of the behavior of river suspended ( > 0.45\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreaterµm) matter (RSM) in these regions. In order to test the effect of climate, permafrost and physio-geographical landscape parameters (bogs, forest and lake coverage of the watershed) on RSM and particulate C, N and P concentrations in river water, we sampled 33 small and medium-sized rivers (10–100\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater000\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreaterkm$^{\\textrm{2}}$ watershed) along a 1700\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreaterkm N–S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL). The concentrations of C and N in RSM decreased with the increase in river watershed size, illustrating (i) the importance of organic debris in small rivers which drain peatlands and (ii) the role of mineral matter from bank abrasion in larger rivers. The presence of lakes in the watershed increased C and N but decreased P concentrations in the RSM. The C : N ratio in the RSM reflected the source from the deep soil horizon rather than surface soil horizon, similar to that of other Arctic rivers. This suggests the export of peat and mineral particles through suprapermafrost flow occurring at the base of the active layer. There was a maximum of both particulate C and N concentrations and export fluxes at the beginning of permafrost appearance, in the sporadic and discontinuous zone (62–64°\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreaterN). This presumably reflected the organic matter mobilization from newly thawed organic horizons in soils at the active latitudinal thawing front. The results suggest that a northward shift of permafrost boundaries and an increase in active layer thickness may increase particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2, while P export may remain unchanged. In contrast, within a long-term climate warming scenario, the disappearance of permafrost in the north, the drainage of lakes and transformation of bogs to forest may decrease C and N concentrations in RSM by 2 to 3 times.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern Siberia.\n \n \n \n \n\n\n \n Walz, J.; Knoblauch, C.; Tigges, R.; Opel, T.; Schirrmeister, L.; and Pfeiffer, E.\n\n\n \n\n\n\n Biogeosciences, 15(17): 5423–5436. September 2018.\n Publisher: Copernicus GmbH\n\n\n\n
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\n\n\n@article{walz_greenhouse_2018,\n\ttitle = {Greenhouse gas production in degrading ice-rich permafrost deposits in northeastern {Siberia}},\n\tvolume = {15},\n\tissn = {1726-4170},\n\turl = {https://www.biogeosciences.net/15/5423/2018/},\n\tdoi = {10.5194/bg-15-5423-2018},\n\tabstract = {{\\textless}p{\\textgreater}{\\textless}strong{\\textgreater}Abstract.{\\textless}/strong{\\textgreater} Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide ({\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater}) and methane ({\\textless}span class="inline-formula"{\\textgreater}CH$_{\\textrm{4}}${\\textless}/span{\\textgreater}) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production as a result of degrading ice-rich permafrost deposits from three locations in the northeastern Siberian Laptev Sea region. The deposits span a period of about 55\\ kyr from the last glacial period and Holocene interglacial. Samples from all three locations were incubated under aerobic and anaerobic conditions for 134 days at 4\\ {\\textless}span class="inline-formula"{\\textgreater}$^{\\textrm{∘}}${\\textless}/span{\\textgreater}C. Greenhouse gas production was generally higher in deposits from glacial periods, where 0.2\\ \\%–6.1\\ \\% of the initially available OC was decomposed to {\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater}. In contrast, only 0.1\\ \\%–4.0\\ \\% of initial OC was decomposed in permafrost deposits from the Holocene and the late glacial transition. Within the deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the greenhouse gas production potentials over longer periods, deposits from two locations were incubated for a total of 785 days. However, more than 50\\ \\% of total {\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater} production over 785 days occurred within the first 134 days under aerobic conditions, while 80\\ \\% were produced over the same period under anaerobic conditions, which emphasizes the nonlinearity of the OC decomposition processes. Methanogenesis was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than {\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater} production.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\tnumber = {17},\n\turldate = {2020-06-10},\n\tjournal = {Biogeosciences},\n\tauthor = {Walz, Josefine and Knoblauch, Christian and Tigges, Ronja and Opel, Thomas and Schirrmeister, Lutz and Pfeiffer, Eva-Maria},\n\tmonth = sep,\n\tyear = {2018},\n\tnote = {Publisher: Copernicus GmbH},\n\tkeywords = {\\#nosource},\n\tpages = {5423--5436},\n}\n\n\n\n\n\n \\textlessp\\textgreater\\textlessstrong\\textgreaterAbstract.\\textless/strong\\textgreater Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide (\\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater) and methane (\\textlessspan class=\"inline-formula\"\\textgreaterCH$_{\\textrm{4}}$\\textless/span\\textgreater) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production as a result of degrading ice-rich permafrost deposits from three locations in the northeastern Siberian Laptev Sea region. The deposits span a period of about 55 kyr from the last glacial period and Holocene interglacial. Samples from all three locations were incubated under aerobic and anaerobic conditions for 134 days at 4 \\textlessspan class=\"inline-formula\"\\textgreater$^{\\textrm{∘}}$\\textless/span\\textgreaterC. Greenhouse gas production was generally higher in deposits from glacial periods, where 0.2 %–6.1 % of the initially available OC was decomposed to \\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater. In contrast, only 0.1 %–4.0 % of initial OC was decomposed in permafrost deposits from the Holocene and the late glacial transition. Within the deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the greenhouse gas production potentials over longer periods, deposits from two locations were incubated for a total of 785 days. However, more than 50 % of total \\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater production over 785 days occurred within the first 134 days under aerobic conditions, while 80 % were produced over the same period under anaerobic conditions, which emphasizes the nonlinearity of the OC decomposition processes. Methanogenesis was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than \\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater production.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n The Sphagnome Project: enabling ecological and evolutionary insights through a genus-level sequencing project.\n \n \n \n \n\n\n \n Weston, D. J.; Turetsky, M. R.; Johnson, M. G.; Granath, G.; Lindo, Z.; Belyea, L. R.; Rice, S. K.; Hanson, D. T.; Engelhardt, K. A. M.; Schmutz, J.; Dorrepaal, E.; Euskirchen, E. S.; Stenøien, H. K.; Szövényi, P.; Jackson, M.; Piatkowski, B. T.; Muchero, W.; Norby, R. J.; Kostka, J. E.; Glass, J. B.; Rydin, H.; Limpens, J.; Tuittila, E.; Ullrich, K. K.; Carrell, A.; Benscoter, B. W.; Chen, J.; Oke, T. A.; Nilsson, M. B.; Ranjan, P.; Jacobson, D.; Lilleskov, E. A.; Clymo, R. S.; and Shaw, A. J.\n\n\n \n\n\n\n New Phytologist, 217(1): 16–25. January 2018.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{weston_sphagnome_2018,\n\ttitle = {The {Sphagnome} {Project}: enabling ecological and evolutionary insights through a genus-level sequencing project},\n\tvolume = {217},\n\tissn = {0028-646X},\n\turl = {https://doi.org/10.1111/nph.14860},\n\tdoi = {10.1111/nph.14860},\n\tabstract = {Summary Considerable progress has been made in ecological and evolutionary genetics with studies demonstrating how genes underlying plant and microbial traits can influence adaptation and even ?extend? to influence community structure and ecosystem level processes. Progress in this area is limited to model systems with deep genetic and genomic resources that often have negligible ecological impact or interest. Thus, important linkages between genetic adaptations and their consequences at organismal and ecological scales are often lacking. Here we introduce the Sphagnome Project, which incorporates genomics into a long-running history of Sphagnum research that has documented unparalleled contributions to peatland ecology, carbon sequestration, biogeochemistry, microbiome research, niche construction, and ecosystem engineering. The Sphagnome Project encompasses a genus-level sequencing effort that represents a new type of model system driven not only by genetic tractability, but by ecologically relevant questions and hypotheses.},\n\tnumber = {1},\n\turldate = {2023-07-21},\n\tjournal = {New Phytologist},\n\tauthor = {Weston, David J. and Turetsky, Merritt R. and Johnson, Matthew G. and Granath, Gustaf and Lindo, Zoë and Belyea, Lisa R. and Rice, Steven K. and Hanson, David T. and Engelhardt, Katharina A. M. and Schmutz, Jeremy and Dorrepaal, Ellen and Euskirchen, Eugénie S. and Stenøien, Hans K. and Szövényi, Péter and Jackson, Michelle and Piatkowski, Bryan T. and Muchero, Wellington and Norby, Richard J. and Kostka, Joel E. and Glass, Jennifer B. and Rydin, Håkan and Limpens, Juul and Tuittila, Eeva-Stiina and Ullrich, Kristian K. and Carrell, Alyssa and Benscoter, Brian W. and Chen, Jin-Gui and Oke, Tobi A. and Nilsson, Mats B. and Ranjan, Priya and Jacobson, Daniel and Lilleskov, Erik A. and Clymo, R. S. and Shaw, A. Jonathan},\n\tmonth = jan,\n\tyear = {2018},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, Sphagnome, Sphagnum, ecological genomics, ecosystem engineering, evolutionary genetics, genome sequencing, niche construction, peatlands},\n\tpages = {16--25},\n}\n\n\n\n\n\n Summary Considerable progress has been made in ecological and evolutionary genetics with studies demonstrating how genes underlying plant and microbial traits can influence adaptation and even ?extend? to influence community structure and ecosystem level processes. Progress in this area is limited to model systems with deep genetic and genomic resources that often have negligible ecological impact or interest. Thus, important linkages between genetic adaptations and their consequences at organismal and ecological scales are often lacking. Here we introduce the Sphagnome Project, which incorporates genomics into a long-running history of Sphagnum research that has documented unparalleled contributions to peatland ecology, carbon sequestration, biogeochemistry, microbiome research, niche construction, and ecosystem engineering. The Sphagnome Project encompasses a genus-level sequencing effort that represents a new type of model system driven not only by genetic tractability, but by ecologically relevant questions and hypotheses.\n
\n\n\n\n \n\n \n \n \n \n \n \n Detecting macroecological patterns in bacterial communities across independent studies of global soils.\n \n \n \n \n\n\n \n Ramirez, K. S.; Knight, C. G.; de Hollander, M.; Brearley, F. Q.; Constantinides, B.; Cotton, A.; Creer, S.; Crowther, T. W.; Davison, J.; Delgado-Baquerizo, M.; Dorrepaal, E.; Elliott, D. R.; Fox, G.; Griffiths, R. I.; Hale, C.; Hartman, K.; Houlden, A.; Jones, D. L.; Krab, E. J.; Maestre, F. T.; McGuire, K. L.; Monteux, S.; Orr, C. H.; van der Putten, W. H.; Roberts, I. S.; Robinson, D. A.; Rocca, J. D.; Rowntree, J.; Schlaeppi, K.; Shepherd, M.; Singh, B. K.; Straathof, A. L.; Bhatnagar, J. M.; Thion, C.; van der Heijden, M. G. A.; and de Vries, F. T.\n\n\n \n\n\n\n Nature Microbiology, 3(2): 189–196. February 2018.\n \n\n\n\n
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\n\n\n@article{ramirez_detecting_2018,\n\ttitle = {Detecting macroecological patterns in bacterial communities across independent studies of global soils},\n\tvolume = {3},\n\tissn = {2058-5276},\n\turl = {https://doi.org/10.1038/s41564-017-0062-x},\n\tdoi = {10.1038/s41564-017-0062-x},\n\tabstract = {The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential ‘indicator’ taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.},\n\tnumber = {2},\n\tjournal = {Nature Microbiology},\n\tauthor = {Ramirez, Kelly S. and Knight, Christopher G. and de Hollander, Mattias and Brearley, Francis Q. and Constantinides, Bede and Cotton, Anne and Creer, Si and Crowther, Thomas W. and Davison, John and Delgado-Baquerizo, Manuel and Dorrepaal, Ellen and Elliott, David R. and Fox, Graeme and Griffiths, Robert I. and Hale, Chris and Hartman, Kyle and Houlden, Ashley and Jones, David L. and Krab, Eveline J. and Maestre, Fernando T. and McGuire, Krista L. and Monteux, Sylvain and Orr, Caroline H. and van der Putten, Wim H. and Roberts, Ian S. and Robinson, David A. and Rocca, Jennifer D. and Rowntree, Jennifer and Schlaeppi, Klaus and Shepherd, Matthew and Singh, Brajesh K. and Straathof, Angela L. and Bhatnagar, Jennifer M. and Thion, Cécile and van der Heijden, Marcel G. A. and de Vries, Franciska T.},\n\tmonth = feb,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {189--196},\n}\n\n\n\n\n\n The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential ‘indicator’ taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.\n
\n\n\n\n \n\n \n \n \n \n \n \n Vascular plant-mediated controls on atmospheric carbon assimilation and peat carbon decomposition under climate change.\n \n \n \n \n\n\n \n Gavazov, K.; Albrecht, R.; Buttler, A.; Dorrepaal, E.; Garnett, M. H.; Gogo, S.; Hagedorn, F.; Mills, R. T. E.; Robroek, B. J. M.; and Bragazza, L.\n\n\n \n\n\n\n Global Change Biology, 24(9): 3911–3921. September 2018.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{gavazov_vascular_2018,\n\ttitle = {Vascular plant-mediated controls on atmospheric carbon assimilation and peat carbon decomposition under climate change},\n\tvolume = {24},\n\tissn = {1354-1013},\n\turl = {https://doi.org/10.1111/gcb.14140},\n\tdoi = {10.1111/gcb.14140},\n\tabstract = {Abstract Climate change can alter peatland plant community composition by promoting the growth of vascular plants. How such vegetation change affects peatland carbon dynamics remains, however, unclear. In order to assess the effect of vegetation change on carbon uptake and release, we performed a vascular plant-removal experiment in two Sphagnum-dominated peatlands that represent contrasting stages of natural vegetation succession along a climatic gradient. Periodic measurements of net ecosystem CO2 exchange revealed that vascular plants play a crucial role in assuring the potential for net carbon uptake, particularly with a warmer climate. The presence of vascular plants, however, also increased ecosystem respiration, and by using the seasonal variation of respired CO2 radiocarbon (bomb-14C) signature we demonstrate an enhanced heterotrophic decomposition of peat carbon due to rhizosphere priming. The observed rhizosphere priming of peat carbon decomposition was matched by more advanced humification of dissolved organic matter, which remained apparent beyond the plant growing season. Our results underline the relevance of rhizosphere priming in peatlands, especially when assessing the future carbon sink function of peatlands undergoing a shift in vegetation community composition in association with climate change.},\n\tnumber = {9},\n\turldate = {2023-07-21},\n\tjournal = {Global Change Biology},\n\tauthor = {Gavazov, Konstantin and Albrecht, Remy and Buttler, Alexandre and Dorrepaal, Ellen and Garnett, Mark H. and Gogo, Sebastien and Hagedorn, Frank and Mills, Robert T. E. and Robroek, Bjorn J. M. and Bragazza, Luca},\n\tmonth = sep,\n\tyear = {2018},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, climate warming, decomposition, ecosystem respiration, elevation gradient, net ecosystem CO2 exchange, peatlands, rhizosphere priming, vascular plant biomass},\n\tpages = {3911--3921},\n}\n\n\n\n\n\n Abstract Climate change can alter peatland plant community composition by promoting the growth of vascular plants. How such vegetation change affects peatland carbon dynamics remains, however, unclear. In order to assess the effect of vegetation change on carbon uptake and release, we performed a vascular plant-removal experiment in two Sphagnum-dominated peatlands that represent contrasting stages of natural vegetation succession along a climatic gradient. Periodic measurements of net ecosystem CO2 exchange revealed that vascular plants play a crucial role in assuring the potential for net carbon uptake, particularly with a warmer climate. The presence of vascular plants, however, also increased ecosystem respiration, and by using the seasonal variation of respired CO2 radiocarbon (bomb-14C) signature we demonstrate an enhanced heterotrophic decomposition of peat carbon due to rhizosphere priming. The observed rhizosphere priming of peat carbon decomposition was matched by more advanced humification of dissolved organic matter, which remained apparent beyond the plant growing season. Our results underline the relevance of rhizosphere priming in peatlands, especially when assessing the future carbon sink function of peatlands undergoing a shift in vegetation community composition in association with climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-term in situ permafrost thaw effects on bacterial communities and potential aerobic respiration.\n \n \n \n \n\n\n \n Monteux, S.; Weedon, J. T.; Blume-Werry, G.; Gavazov, K.; Jassey, V. E. J.; Johansson, M.; Keuper, F.; Olid, C.; and Dorrepaal, E.\n\n\n \n\n\n\n The ISME Journal, 12(9): 2129–2141. September 2018.\n \n\n\n\n
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\n\n\n@article{monteux_long-term_2018,\n\ttitle = {Long-term in situ permafrost thaw effects on bacterial communities and potential aerobic respiration},\n\tvolume = {12},\n\tissn = {1751-7370},\n\turl = {https://doi.org/10.1038/s41396-018-0176-z},\n\tdoi = {10.1038/s41396-018-0176-z},\n\tabstract = {The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential respiration at different depths, and the extent to which they are related with each other and with root density. Active layer and permafrost BCS strongly differed, and the BCS in formerly frozen soils (below the natural thawfront) converged under induced deep thaw to strongly resemble the active layer BCS, possibly as a result of colonization by overlying microorganisms. Overall, respiration rates decreased with depth and soils showed lower potential respiration when subjected to deeper thaw, which we attributed to gradual labile carbon pool depletion. Despite deeper rooting under induced deep thaw, root density measurements did not improve soil chemistry-based models of potential respiration. However, BCS explained an additional unique portion of variation in respiration, particularly when accounting for differences in organic matter content. Our results suggest that by measuring bacterial community composition, we can improve both our understanding and the modeling of the permafrost carbon feedback.},\n\tnumber = {9},\n\tjournal = {The ISME Journal},\n\tauthor = {Monteux, Sylvain and Weedon, James T. and Blume-Werry, Gesche and Gavazov, Konstantin and Jassey, Vincent E. J. and Johansson, Margareta and Keuper, Frida and Olid, Carolina and Dorrepaal, Ellen},\n\tmonth = sep,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {2129--2141},\n}\n\n\n\n\n\n The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential respiration at different depths, and the extent to which they are related with each other and with root density. Active layer and permafrost BCS strongly differed, and the BCS in formerly frozen soils (below the natural thawfront) converged under induced deep thaw to strongly resemble the active layer BCS, possibly as a result of colonization by overlying microorganisms. Overall, respiration rates decreased with depth and soils showed lower potential respiration when subjected to deeper thaw, which we attributed to gradual labile carbon pool depletion. Despite deeper rooting under induced deep thaw, root density measurements did not improve soil chemistry-based models of potential respiration. However, BCS explained an additional unique portion of variation in respiration, particularly when accounting for differences in organic matter content. Our results suggest that by measuring bacterial community composition, we can improve both our understanding and the modeling of the permafrost carbon feedback.\n
\n\n\n\n \n\n \n \n \n \n \n \n Terrestrial support of zooplankton biomass in northern rivers.\n \n \n \n \n\n\n \n Berggren, M.; Bengtson, P.; Soares, A. R. A.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 63(6): 2479–2492. 2018.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10954\n\n\n\n
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\n\n\n@article{berggren_terrestrial_2018,\n\ttitle = {Terrestrial support of zooplankton biomass in northern rivers},\n\tvolume = {63},\n\tcopyright = {© 2018 Association for the Sciences of Limnology and Oceanography},\n\tissn = {1939-5590},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.10954},\n\tdoi = {10.1002/lno.10954},\n\tabstract = {The contribution of terrestrially derived carbon to micro-crustacean zooplankton biomass (i.e., allochthony) has been previously studied in lakes, reservoirs, and estuaries, but little is known about zooplankton allochthony in rivers. In lacustrine environments, allochthony is regulated by distinct selective feeding behavior of different taxa. However, we hypothesized that restricted possibility for selective grazing in turbulent environments such as rivers would decouple zooplankton from specific microbial and algal food resources, such that their allochthony would mirror the terrestrial contribution to the surrounding bulk particle pool. We tested this idea by analyzing allochthony in 13 widely distributed Swedish rivers, using a dual-isotope mixing model. Zooplankton biomasses were generally low, and allochthony in different micro-crustacean groups (Cladocera, Cyclopoida, Calanoida) varied from 2\\% to 77\\%. As predicted, there were no correlations between allochthony and variables indicating the supply of algal and microbial food resources, such as chlorophyll a and bacterial production. Instead, the allochthony was generally similar to the share allochthonous contribution in bulk particulate organic matter, with relationships close to the 1 : 1 line. The zooplankton community allochthony was strongly regulated by the ecosystem metabolic balance between production and respiration, which in turn was dependent upon the ratio between total autochthonous organic carbon concentrations and water color. Our study for the first time shows that micro-crustacean allochthony is regulated differently in rivers compared to in lacustrine systems, and points to inefficient support of zooplankton biomass by algal resources in turbulent waters.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2023-07-20},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Berggren, M. and Bengtson, P. and Soares, A. R. A. and Karlsson, J.},\n\tyear = {2018},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lno.10954},\n\tkeywords = {\\#nosource},\n\tpages = {2479--2492},\n}\n\n\n\n\n\n The contribution of terrestrially derived carbon to micro-crustacean zooplankton biomass (i.e., allochthony) has been previously studied in lakes, reservoirs, and estuaries, but little is known about zooplankton allochthony in rivers. In lacustrine environments, allochthony is regulated by distinct selective feeding behavior of different taxa. However, we hypothesized that restricted possibility for selective grazing in turbulent environments such as rivers would decouple zooplankton from specific microbial and algal food resources, such that their allochthony would mirror the terrestrial contribution to the surrounding bulk particle pool. We tested this idea by analyzing allochthony in 13 widely distributed Swedish rivers, using a dual-isotope mixing model. Zooplankton biomasses were generally low, and allochthony in different micro-crustacean groups (Cladocera, Cyclopoida, Calanoida) varied from 2% to 77%. As predicted, there were no correlations between allochthony and variables indicating the supply of algal and microbial food resources, such as chlorophyll a and bacterial production. Instead, the allochthony was generally similar to the share allochthonous contribution in bulk particulate organic matter, with relationships close to the 1 : 1 line. The zooplankton community allochthony was strongly regulated by the ecosystem metabolic balance between production and respiration, which in turn was dependent upon the ratio between total autochthonous organic carbon concentrations and water color. Our study for the first time shows that micro-crustacean allochthony is regulated differently in rivers compared to in lacustrine systems, and points to inefficient support of zooplankton biomass by algal resources in turbulent waters.\n
\n\n\n\n \n\n \n \n \n \n \n \n Using stable isotopes to assess surface water source dynamics and hydrological connectivity in a high-latitude wetland and permafrost influenced landscape.\n \n \n \n \n\n\n \n Ala-aho, P.; Soulsby, C.; Pokrovsky, O. S.; Kirpotin, S. N.; Karlsson, J.; Serikova, S.; Vorobyev, S. N.; Manasypov, R. M.; Loiko, S.; and Tetzlaff, D.\n\n\n \n\n\n\n Journal of Hydrology, 556: 279–293. January 2018.\n \n\n\n\n
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\n\n\n@article{ala-aho_using_2018,\n\ttitle = {Using stable isotopes to assess surface water source dynamics and hydrological connectivity in a high-latitude wetland and permafrost influenced landscape},\n\tvolume = {556},\n\tissn = {0022-1694},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0022169417307874},\n\tdoi = {10.1016/j.jhydrol.2017.11.024},\n\tabstract = {Climate change is expected to alter hydrological and biogeochemical processes in high-latitude inland waters. A critical question for understanding contemporary and future responses to environmental change is how the spatio-temporal dynamics of runoff generation processes will be affected. We sampled stable water isotopes in soils, lakes and rivers on an unprecedented spatio-temporal scale along a 1700 km transect over three years in the Western Siberia Lowlands. Our findings suggest that snowmelt mixes with, and displaces, large volumes of water stored in the organic soils and lakes to generate runoff during the thaw season. Furthermore, we saw a persistent hydrological connection between water bodies and the landscape across permafrost regions. Our findings help to bridge the understanding between small and large scale hydrological studies in high-latitude systems. These isotope data provide a means to conceptualise hydrological connectivity in permafrost and wetland influenced regions, which is needed for an improved understanding of future biogeochemical changes.},\n\tlanguage = {en},\n\turldate = {2023-07-20},\n\tjournal = {Journal of Hydrology},\n\tauthor = {Ala-aho, P. and Soulsby, C. and Pokrovsky, O. S. and Kirpotin, S. N. and Karlsson, J. and Serikova, S. and Vorobyev, S. N. and Manasypov, R. M. and Loiko, S. and Tetzlaff, D.},\n\tmonth = jan,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Hydrological connectivity, Low-relief, Runoff generation, Snowmelt, Stable water isotopes},\n\tpages = {279--293},\n}\n\n\n\n\n\n Climate change is expected to alter hydrological and biogeochemical processes in high-latitude inland waters. A critical question for understanding contemporary and future responses to environmental change is how the spatio-temporal dynamics of runoff generation processes will be affected. We sampled stable water isotopes in soils, lakes and rivers on an unprecedented spatio-temporal scale along a 1700 km transect over three years in the Western Siberia Lowlands. Our findings suggest that snowmelt mixes with, and displaces, large volumes of water stored in the organic soils and lakes to generate runoff during the thaw season. Furthermore, we saw a persistent hydrological connection between water bodies and the landscape across permafrost regions. Our findings help to bridge the understanding between small and large scale hydrological studies in high-latitude systems. These isotope data provide a means to conceptualise hydrological connectivity in permafrost and wetland influenced regions, which is needed for an improved understanding of future biogeochemical changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Proportion of fine roots, but not plant biomass allocation belowground, increases with elevation in arctic tundra.\n \n \n \n \n\n\n \n Blume-Werry, G.; Lindén, E.; Andresen, L.; Classen, A. T.; Sanders, N. J.; von Oppen, J.; and Sundqvist, M. K.\n\n\n \n\n\n\n Journal of Vegetation Science, 29: 226–235. 2018.\n 00000\n\n\n\n
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\n\n\n@article{blume-werry_proportion_2018,\n\ttitle = {Proportion of fine roots, but not plant biomass allocation belowground, increases with elevation in arctic tundra},\n\tvolume = {29},\n\tissn = {1654-1103},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/jvs.12605/abstract},\n\tdoi = {10.1111/jvs.12605},\n\tabstract = {Questions\n\nRoots represent a considerable proportion of biomass, primary production, and litter input in arctic tundra, and plant allocation of biomass to above- or belowground tissue in response to climate change is a key factor in the future carbon balance of these ecosystems. According to optimality theory plants allocate carbon to the above- or belowground structure that captures the most limiting resource. We used an elevational gradient to test this theory and as a space-for-time substitution to inform on tundra carbon allocation patterns under a shifting climate, by exploring if increasing elevation was positively related to the root:shoot ratio, as well as a greater plant allocation to adsorptive over storage roots.\n\n\nLocation\n\nArctic tundra heath dominated by Empetrum hermaphroditum close to Abisko, Sweden.\n\n\nMethods\n\nWe measured root:shoot and fine:coarse root ratios of the plant communities along an elevational gradient by sampling above- and belowground biomass, further separating root biomass into fine ({\\textless} 1 mm) and coarse roots.\n\n\nResults\n\nPlant biomass was higher at the lower elevations, but the root:shoot ratio did not vary with elevation. Resource allocation to fine relative to coarse roots increased with elevation, resulting in a fine:coarse root ratio that more than doubled with increasing elevation.\n\n\nConclusions\n\nContrary to previous works, the root:shoot ratio along this elevational gradient remained stable. However, communities along our study system were dominated by the same species at each elevation which suggests that when changes in the root:shoot ratio occur with elevation these changes may be driven by differences in allocation patterns among species and thus turnover in plant community structure. Our results further reveal that the allocation of biomass to fine relative to coarse roots can differ between locations along an elevational gradient even when overall above- versus belowground biomass allocation does not. Given the functionally different roles of fine versus coarse roots this could have large implications for belowground carbon cycling. Our results highlight the importance of direct effects versus indirect effects (such as changes in plant community composition and nutrient availability) of climate change for future carbon allocation above- and belowground.\nThis article is protected by copyright. All rights reserved.},\n\tlanguage = {en},\n\turldate = {2018-01-02},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Blume-Werry, Gesche and Lindén, Elin and Andresen, Lisa and Classen, Aimée T. and Sanders, Nathan J. and von Oppen, Jonathan and Sundqvist, Maja K.},\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Above- and belowground linkages, Betula nana, Empetrum hermaphroditum, above- and below-ground linkages, arctic tundra, biomass allocation, elevational gradient, fine roots, heath vegetation},\n\tpages = {226--235},\n}\n\n\n\n\n\n Questions Roots represent a considerable proportion of biomass, primary production, and litter input in arctic tundra, and plant allocation of biomass to above- or belowground tissue in response to climate change is a key factor in the future carbon balance of these ecosystems. According to optimality theory plants allocate carbon to the above- or belowground structure that captures the most limiting resource. We used an elevational gradient to test this theory and as a space-for-time substitution to inform on tundra carbon allocation patterns under a shifting climate, by exploring if increasing elevation was positively related to the root:shoot ratio, as well as a greater plant allocation to adsorptive over storage roots. Location Arctic tundra heath dominated by Empetrum hermaphroditum close to Abisko, Sweden. Methods We measured root:shoot and fine:coarse root ratios of the plant communities along an elevational gradient by sampling above- and belowground biomass, further separating root biomass into fine (\\textless 1 mm) and coarse roots. Results Plant biomass was higher at the lower elevations, but the root:shoot ratio did not vary with elevation. Resource allocation to fine relative to coarse roots increased with elevation, resulting in a fine:coarse root ratio that more than doubled with increasing elevation. Conclusions Contrary to previous works, the root:shoot ratio along this elevational gradient remained stable. However, communities along our study system were dominated by the same species at each elevation which suggests that when changes in the root:shoot ratio occur with elevation these changes may be driven by differences in allocation patterns among species and thus turnover in plant community structure. Our results further reveal that the allocation of biomass to fine relative to coarse roots can differ between locations along an elevational gradient even when overall above- versus belowground biomass allocation does not. Given the functionally different roles of fine versus coarse roots this could have large implications for belowground carbon cycling. Our results highlight the importance of direct effects versus indirect effects (such as changes in plant community composition and nutrient availability) of climate change for future carbon allocation above- and belowground. This article is protected by copyright. All rights reserved.\n
\n\n\n\n \n\n \n \n \n \n \n \n Greenhouse gas emissions from boreal inland waters unchanged after forest harvesting.\n \n \n \n \n\n\n \n Klaus, M.; Geibrink, E.; Jonsson, A.; Bergström, A.; Bastviken, D.; Laudon, H.; Klaminder, J.; and Karlsson, J.\n\n\n \n\n\n\n Biogeosciences, 15(18): 5575–5594. September 2018.\n \n\n\n\n
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\n\n\n@article{klaus_greenhouse_2018,\n\ttitle = {Greenhouse gas emissions from boreal inland waters unchanged after forest harvesting},\n\tvolume = {15},\n\tissn = {1726-4170},\n\turl = {https://www.biogeosciences.net/15/5575/2018/},\n\tdoi = {10.5194/bg-15-5575-2018},\n\tabstract = {{\\textless}p{\\textgreater}{\\textless}strong{\\textgreater}Abstract.{\\textless}/strong{\\textgreater} Forestry practices often result in an increased export of carbon and nitrogen to downstream aquatic systems. Although these losses affect the greenhouse gas (GHG) budget of managed forests, it is unknown if they modify GHG emissions of recipient aquatic systems. To assess this question, air–water fluxes of carbon dioxide ({\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater}), methane ({\\textless}span class="inline-formula"{\\textgreater}CH$_{\\textrm{4}}${\\textless}/span{\\textgreater}) and nitrous oxide ({\\textless}span class="inline-formula"{\\textgreater}N$_{\\textrm{2}}$O{\\textless}/span{\\textgreater}) were quantified for humic lakes and their inlet streams in four boreal catchments using a before-after control-impact experiment. Two catchments were treated with forest clear-cuts followed by site preparation (18{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\% and 44{\\textless}span class="thinspace"{\\textgreater}{\\textless}/span{\\textgreater}\\% of the catchment area). GHG fluxes and hydrological and physicochemical water characteristics were measured at multiple locations in lakes and streams at high temporal resolution throughout the summer season over a 4-year period. Both lakes and streams evaded all GHGs. The treatment did not significantly change GHG fluxes in streams or lakes within 3 years after the treatment, despite significant increases of {\\textless}span class="inline-formula"{\\textgreater}CO$_{\\textrm{2}}${\\textless}/span{\\textgreater} and {\\textless}span class="inline-formula"{\\textgreater}CH$_{\\textrm{4}}${\\textless}/span{\\textgreater} concentrations in hillslope groundwater. Our results highlight that GHGs leaching from forest clear-cuts may be buffered in the riparian zone–stream continuum, likely acting as effective biogeochemical processors and wind shelters to prevent additional GHG evasion via downstream inland waters. These findings are representative of low productive forests located in relatively flat landscapes where forestry practices cause only a limited initial impact on catchment hydrology and biogeochemistry.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\tnumber = {18},\n\turldate = {2019-05-06},\n\tjournal = {Biogeosciences},\n\tauthor = {Klaus, Marcus and Geibrink, Erik and Jonsson, Anders and Bergström, Ann-Kristin and Bastviken, David and Laudon, Hjalmar and Klaminder, Jonatan and Karlsson, Jan},\n\tmonth = sep,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {5575--5594},\n}\n\n\n\n\n\n \\textlessp\\textgreater\\textlessstrong\\textgreaterAbstract.\\textless/strong\\textgreater Forestry practices often result in an increased export of carbon and nitrogen to downstream aquatic systems. Although these losses affect the greenhouse gas (GHG) budget of managed forests, it is unknown if they modify GHG emissions of recipient aquatic systems. To assess this question, air–water fluxes of carbon dioxide (\\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater), methane (\\textlessspan class=\"inline-formula\"\\textgreaterCH$_{\\textrm{4}}$\\textless/span\\textgreater) and nitrous oxide (\\textlessspan class=\"inline-formula\"\\textgreaterN$_{\\textrm{2}}$O\\textless/span\\textgreater) were quantified for humic lakes and their inlet streams in four boreal catchments using a before-after control-impact experiment. Two catchments were treated with forest clear-cuts followed by site preparation (18\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater% and 44\\textlessspan class=\"thinspace\"\\textgreater\\textless/span\\textgreater% of the catchment area). GHG fluxes and hydrological and physicochemical water characteristics were measured at multiple locations in lakes and streams at high temporal resolution throughout the summer season over a 4-year period. Both lakes and streams evaded all GHGs. The treatment did not significantly change GHG fluxes in streams or lakes within 3 years after the treatment, despite significant increases of \\textlessspan class=\"inline-formula\"\\textgreaterCO$_{\\textrm{2}}$\\textless/span\\textgreater and \\textlessspan class=\"inline-formula\"\\textgreaterCH$_{\\textrm{4}}$\\textless/span\\textgreater concentrations in hillslope groundwater. Our results highlight that GHGs leaching from forest clear-cuts may be buffered in the riparian zone–stream continuum, likely acting as effective biogeochemical processors and wind shelters to prevent additional GHG evasion via downstream inland waters. These findings are representative of low productive forests located in relatively flat landscapes where forestry practices cause only a limited initial impact on catchment hydrology and biogeochemistry.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n Predicting global scale exposure of humans to PCB 153 from historical emissions.\n \n \n \n \n\n\n \n McLachlan, M. S.; Undeman, E.; Zhao, F.; and MacLeod, M.\n\n\n \n\n\n\n Environmental Science: Processes & Impacts, 20(5): 747–756. 2018.\n \n\n\n\n
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\n\n\n\n@article{mclachlan_predicting_2018,\n\ttitle = {Predicting global scale exposure of humans to {PCB} 153 from historical emissions},\n\tvolume = {20},\n\tissn = {2050-7887, 2050-7895},\n\turl = {http://xlink.rsc.org/?DOI=C8EM00023A},\n\tdoi = {10.1039/C8EM00023A},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2019-04-23},\n\tjournal = {Environmental Science: Processes \\& Impacts},\n\tauthor = {McLachlan, Michael S. and Undeman, Emma and Zhao, Fangyuan and MacLeod, Matthew},\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {747--756},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Microbial temperature sensitivity and biomass change explain soil carbon loss with warming.\n \n \n \n \n\n\n \n Walker, T. W. N.; Kaiser, C.; Strasser, F.; Herbold, C. W.; Leblans, N. I. W.; Woebken, D.; Janssens, I. A.; Sigurdsson, B. D.; and Richter, A.\n\n\n \n\n\n\n Nature Climate Change, 8(10): 885. October 2018.\n \n\n\n\n
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\n\n\n@article{walker_microbial_2018,\n\ttitle = {Microbial temperature sensitivity and biomass change explain soil carbon loss with warming},\n\tvolume = {8},\n\tcopyright = {2018 The Author(s)},\n\tissn = {1758-6798},\n\turl = {https://www.nature.com/articles/s41558-018-0259-x},\n\tdoi = {10.1038/s41558-018-0259-x},\n\tabstract = {Soil microbial activity is accelerated by warming and does not acclimate over periods of at least 50 years. Resulting soil carbon loss is nevertheless temporary because substrate depletion reduces microbial biomass and constrains the influence of microbes over the ecosystem.},\n\tlanguage = {En},\n\tnumber = {10},\n\turldate = {2019-05-20},\n\tjournal = {Nature Climate Change},\n\tauthor = {Walker, Tom W. N. and Kaiser, Christina and Strasser, Florian and Herbold, Craig W. and Leblans, Niki I. W. and Woebken, Dagmar and Janssens, Ivan A. and Sigurdsson, Bjarni D. and Richter, Andreas},\n\tmonth = oct,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {885},\n}\n\n\n\n\n\n Soil microbial activity is accelerated by warming and does not acclimate over periods of at least 50 years. Resulting soil carbon loss is nevertheless temporary because substrate depletion reduces microbial biomass and constrains the influence of microbes over the ecosystem.\n
\n\n\n\n \n\n \n \n \n \n \n \n Functional diversity of Collembola is reduced in soils subjected to short-term, but not long-term, geothermal warming.\n \n \n \n \n\n\n \n Holmstrup, M.; Ehlers, B. K.; Slotsbo, S.; Ilieva‐Makulec, K.; Sigurdsson, B. D.; Leblans, N. I. W.; Ellers, J.; and Berg, M. P.\n\n\n \n\n\n\n Functional Ecology, 32(5): 1304–1316. 2018.\n \n\n\n\n
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\n\n\n@article{holmstrup_functional_2018,\n\ttitle = {Functional diversity of {Collembola} is reduced in soils subjected to short-term, but not long-term, geothermal warming},\n\tvolume = {32},\n\tcopyright = {© 2018 The Authors. Functional Ecology © 2018 British Ecological Society},\n\tissn = {1365-2435},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.13058},\n\tdoi = {10.1111/1365-2435.13058},\n\tabstract = {Human activities have caused global changes of atmospheric chemistry resulting in increased temperature especially in the colder regions of the northern hemisphere. Since warming of the environment can have drastic effects on terrestrial ecosystems it is important to experimentally evaluate the extent of such effects in long-term field-based experiments. In this study we make use of both recent (short-term) and long-term geothermal warming of Icelandic soils to examine the responses of Collembola, an ecologically important group of soil invertebrates, to warming. On the basis of metabolic scaling theory, we hypothesized that species of small size would be more successful in warmed soils than species of larger size. Further we expected that top-soil-dwelling species would benefit more from warming than deep-soil-dwelling species. In order to test these hypotheses we sampled Collembola along replicated gradients of increasing temperature in areas that had been heated for about 6 years and more than 50 years respectively. Collembola were identified to species level, counted and the community-weighted mean trait scores for six functional and ecological traits were calculated. Results show that both short-term and long-term soil warming caused a shift towards a higher relative abundance of species with small body size. Furthermore, abundance of top-soil-dwelling Collembola tended to increase after short-term warming, but the opposite was observed after long-term warming. Using trait-based diversity indices (FRic and RaoQ), we show that functional richness and diversity of Collembola communities was significantly reduced (almost halved) as a result of short-term soil warming to about 10°C above normal, but this effect was not detected in plots equally warmed for more than 50 years. This indicates that the functional diversity of Collembola communities have high resilience towards soil warming in a long-term perspective. A plain language summary is available for this article.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2019-05-20},\n\tjournal = {Functional Ecology},\n\tauthor = {Holmstrup, Martin and Ehlers, Bodil K. and Slotsbo, Stine and Ilieva‐Makulec, Krassimira and Sigurdsson, Bjarni D. and Leblans, Niki I. W. and Ellers, Jacintha and Berg, Matty P.},\n\tyear = {2018},\n\tkeywords = {\\#nosource, adaptation, ecological traits, global warming, soil ecology, springtails},\n\tpages = {1304--1316},\n}\n\n\n\n\n\n Human activities have caused global changes of atmospheric chemistry resulting in increased temperature especially in the colder regions of the northern hemisphere. Since warming of the environment can have drastic effects on terrestrial ecosystems it is important to experimentally evaluate the extent of such effects in long-term field-based experiments. In this study we make use of both recent (short-term) and long-term geothermal warming of Icelandic soils to examine the responses of Collembola, an ecologically important group of soil invertebrates, to warming. On the basis of metabolic scaling theory, we hypothesized that species of small size would be more successful in warmed soils than species of larger size. Further we expected that top-soil-dwelling species would benefit more from warming than deep-soil-dwelling species. In order to test these hypotheses we sampled Collembola along replicated gradients of increasing temperature in areas that had been heated for about 6 years and more than 50 years respectively. Collembola were identified to species level, counted and the community-weighted mean trait scores for six functional and ecological traits were calculated. Results show that both short-term and long-term soil warming caused a shift towards a higher relative abundance of species with small body size. Furthermore, abundance of top-soil-dwelling Collembola tended to increase after short-term warming, but the opposite was observed after long-term warming. Using trait-based diversity indices (FRic and RaoQ), we show that functional richness and diversity of Collembola communities was significantly reduced (almost halved) as a result of short-term soil warming to about 10°C above normal, but this effect was not detected in plots equally warmed for more than 50 years. This indicates that the functional diversity of Collembola communities have high resilience towards soil warming in a long-term perspective. A plain language summary is available for this article.\n
\n\n\n\n \n\n \n \n \n \n \n \n Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses.\n \n \n \n \n\n\n \n Marañón-Jiménez, S.; Soong, J. L.; Leblans, N. I. W.; Sigurdsson, B. D.; Peñuelas, J.; Richter, A.; Asensio, D.; Fransen, E.; and Janssens, I. A.\n\n\n \n\n\n\n Biogeochemistry, 138(3): 245–260. May 2018.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{maranon-jimenez_geothermally_2018,\n\ttitle = {Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial {C} losses},\n\tvolume = {138},\n\tissn = {1573-515X},\n\turl = {https://doi.org/10.1007/s10533-018-0443-0},\n\tdoi = {10.1007/s10533-018-0443-0},\n\tabstract = {Increasing temperatures can accelerate soil organic matter decomposition and release large amounts of CO2 to the atmosphere, potentially inducing positive warming feedbacks. Alterations to the temperature sensitivity and physiological functioning of soil microorganisms may play a key role in these carbon (C) losses. Geothermally active areas in Iceland provide stable and continuous soil temperature gradients to test this hypothesis, encompassing the full range of warming scenarios projected by the Intergovernmental Panel on Climate Change for the northern region. We took soils from these geothermal sites 7 years after the onset of warming and incubated them at varying temperatures and substrate availability conditions to detect persistent alterations of microbial physiology to long-term warming. Seven years of continuous warming ranging from 1.8 to 15.9 °C triggered a 8.6–58.0\\% decrease on the C concentrations in the topsoil (0–10 cm) of these sub-arctic silt-loam Andosols. The sensitivity of microbial respiration to temperature (Q10) was not altered. However, soil microbes showed a persistent increase in their microbial metabolic quotients (microbial respiration per unit of microbial biomass) and a subsequent diminished C retention in biomass. After an initial depletion of labile soil C upon soil warming, increasing energy costs of metabolic maintenance and resource acquisition led to a weaker capacity of C stabilization in the microbial biomass of warmer soils. This mechanism contributes to our understanding of the acclimated response of soil respiration to in situ soil warming at the ecosystem level, despite a lack of acclimation at the physiological level. Persistent increases in the respiratory costs of soil microbes in response to warming constitute a fundamental process that should be incorporated into climate change-C cycling models.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2019-05-20},\n\tjournal = {Biogeochemistry},\n\tauthor = {Marañón-Jiménez, S. and Soong, J. L. and Leblans, N. I. W. and Sigurdsson, B. D. and Peñuelas, J. and Richter, A. and Asensio, D. and Fransen, E. and Janssens, I. A.},\n\tmonth = may,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Metabolic quotient, Microbial biomass, Microbial physiology, Q10, Soil CO2 fluxes, Soil respiration, Temperature increase},\n\tpages = {245--260},\n}\n\n\n\n\n\n Increasing temperatures can accelerate soil organic matter decomposition and release large amounts of CO2 to the atmosphere, potentially inducing positive warming feedbacks. Alterations to the temperature sensitivity and physiological functioning of soil microorganisms may play a key role in these carbon (C) losses. Geothermally active areas in Iceland provide stable and continuous soil temperature gradients to test this hypothesis, encompassing the full range of warming scenarios projected by the Intergovernmental Panel on Climate Change for the northern region. We took soils from these geothermal sites 7 years after the onset of warming and incubated them at varying temperatures and substrate availability conditions to detect persistent alterations of microbial physiology to long-term warming. Seven years of continuous warming ranging from 1.8 to 15.9 °C triggered a 8.6–58.0% decrease on the C concentrations in the topsoil (0–10 cm) of these sub-arctic silt-loam Andosols. The sensitivity of microbial respiration to temperature (Q10) was not altered. However, soil microbes showed a persistent increase in their microbial metabolic quotients (microbial respiration per unit of microbial biomass) and a subsequent diminished C retention in biomass. After an initial depletion of labile soil C upon soil warming, increasing energy costs of metabolic maintenance and resource acquisition led to a weaker capacity of C stabilization in the microbial biomass of warmer soils. This mechanism contributes to our understanding of the acclimated response of soil respiration to in situ soil warming at the ecosystem level, despite a lack of acclimation at the physiological level. Persistent increases in the respiratory costs of soil microbes in response to warming constitute a fundamental process that should be incorporated into climate change-C cycling models.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lessons learned from monitoring the stable water isotopic variability in precipitation and streamflow across a snow-dominated subarctic catchment.\n \n \n \n \n\n\n \n Lyon, S. W.; Ploum, S. W.; Velde, Y. v. d.; Rocher-Ros, G.; Mörth, C.; and Giesler, R.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 50(1): e1454778. January 2018.\n \n\n\n\n
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\n\n\n@article{lyon_lessons_2018,\n\ttitle = {Lessons learned from monitoring the stable water isotopic variability in precipitation and streamflow across a snow-dominated subarctic catchment},\n\tvolume = {50},\n\tissn = {1523-0430},\n\turl = {https://doi.org/10.1080/15230430.2018.1454778},\n\tdoi = {10.1080/15230430.2018.1454778},\n\tabstract = {This empirical study explores shifts in stable water isotopic composition for a subarctic catchment located in northern Sweden as it transitions from spring freshet to summer low flows. Relative changes in the isotopic composition of streamflow across the main catchment and fifteen nested subcatchments are characterized in relation to the isotopic composition of precipitation. With our sampling campaign, we explore the variability in stream-water isotopic composition that originates from precipitation as the input shifts from snow to rain and as landscape flow pathways change across scales. The isotopic similarity of high-elevation snowpack water and early season rainfall water seen through our sampling scheme made it difficult to truly isolate the impact of seasonal precipitation phase change on stream-water isotopic response. This highlights the need to explicitly consider the complexity of arctic and alpine landscapes when designing sampling strategies to characterize hydrological variability via stable water isotopes. Results show a potential influence of evaporation and source water mixing both spatially (variations with elevation) and temporally (variations from post-freshet to summer flows) on the composition of stream water across Miellajokka. As such, the data collected in this empirical study allow for initial conceptualization of the relative importance of, for example, hydrological connectivity within this mountainous, subarctic landscape.},\n\tnumber = {1},\n\turldate = {2019-08-30},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Lyon, Steve W. and Ploum, Stefan W. and Velde, Ype van der and Rocher-Ros, Gerard and Mörth, Carl-Magnus and Giesler, Reiner},\n\tmonth = jan,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Catchment hydrology, freshet, spring flood, stable water isotopes, tracers},\n\tpages = {e1454778},\n}\n\n\n\n\n\n This empirical study explores shifts in stable water isotopic composition for a subarctic catchment located in northern Sweden as it transitions from spring freshet to summer low flows. Relative changes in the isotopic composition of streamflow across the main catchment and fifteen nested subcatchments are characterized in relation to the isotopic composition of precipitation. With our sampling campaign, we explore the variability in stream-water isotopic composition that originates from precipitation as the input shifts from snow to rain and as landscape flow pathways change across scales. The isotopic similarity of high-elevation snowpack water and early season rainfall water seen through our sampling scheme made it difficult to truly isolate the impact of seasonal precipitation phase change on stream-water isotopic response. This highlights the need to explicitly consider the complexity of arctic and alpine landscapes when designing sampling strategies to characterize hydrological variability via stable water isotopes. Results show a potential influence of evaporation and source water mixing both spatially (variations with elevation) and temporally (variations from post-freshet to summer flows) on the composition of stream water across Miellajokka. As such, the data collected in this empirical study allow for initial conceptualization of the relative importance of, for example, hydrological connectivity within this mountainous, subarctic landscape.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting responses of springtails and mites to elevation and vegetation type in the sub-Arctic.\n \n \n \n \n\n\n \n Bokhorst, S.; (Ciska) Veen, G. F.; Sundqvist, M.; De Long, J. R.; Kardol, P.; and Wardle, D. A.\n\n\n \n\n\n\n Pedobiologia, 67: 57–64. March 2018.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{bokhorst_contrasting_2018,\n\ttitle = {Contrasting responses of springtails and mites to elevation and vegetation type in the sub-{Arctic}},\n\tvolume = {67},\n\tissn = {0031-4056},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0031405617302603},\n\tdoi = {10.1016/j.pedobi.2018.02.004},\n\tabstract = {Climate change is affecting the species composition and functioning of Arctic and sub-Arctic plant and soil communities. Here we studied patterns in soil microarthropod (springtails and mites) communities across a gradient of increasing elevation that spanned 450 m, across which mean temperature declined by approximately 2.5 °C, in sub-Arctic Sweden. Across this gradient we characterized microarthropod communities in each of two types of vegetation, i.e., heath and meadow, to determine whether their responses to declining temperature differed with vegetation type. Mite abundance declined with increasing elevation, while springtail abundance showed the opposite response. Springtail communities were dominated by larger species at higher elevation. Mite abundance was unaffected by vegetation type, while springtail abundance was 53\\% higher in the heath than meadow vegetation across the gradient. Springtails but not mites responded differently to elevation in heath and meadow vegetation; hemi-edaphic species dominated in the heath at higher elevation while epi-edaphic species dominated in the meadow. Our results suggest that sub-Arctic mite and springtail communities will likely respond in contrasting ways to changes in vegetation and soil properties resulting from climate warming.},\n\tlanguage = {en},\n\turldate = {2019-11-05},\n\tjournal = {Pedobiologia},\n\tauthor = {Bokhorst, Stef and (Ciska) Veen, G. F. and Sundqvist, Maja and De Long, Jonathan R. and Kardol, Paul and Wardle, David A.},\n\tmonth = mar,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Acari, Climate change, Collembola, Elevational gradient, Heath, Meadow, Microarthropod},\n\tpages = {57--64},\n}\n\n\n\n\n\n Climate change is affecting the species composition and functioning of Arctic and sub-Arctic plant and soil communities. Here we studied patterns in soil microarthropod (springtails and mites) communities across a gradient of increasing elevation that spanned 450 m, across which mean temperature declined by approximately 2.5 °C, in sub-Arctic Sweden. Across this gradient we characterized microarthropod communities in each of two types of vegetation, i.e., heath and meadow, to determine whether their responses to declining temperature differed with vegetation type. Mite abundance declined with increasing elevation, while springtail abundance showed the opposite response. Springtail communities were dominated by larger species at higher elevation. Mite abundance was unaffected by vegetation type, while springtail abundance was 53% higher in the heath than meadow vegetation across the gradient. Springtails but not mites responded differently to elevation in heath and meadow vegetation; hemi-edaphic species dominated in the heath at higher elevation while epi-edaphic species dominated in the meadow. Our results suggest that sub-Arctic mite and springtail communities will likely respond in contrasting ways to changes in vegetation and soil properties resulting from climate warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Soils beneath different arctic shrubs have contrasting responses to a natural gradient in temperature.\n \n \n \n \n\n\n \n Zhao, Q.; Sundqvist, M. K.; Newman, G. S.; and Classen, A. T.\n\n\n \n\n\n\n Ecosphere, 9(6): e02290. 2018.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{zhao_soils_2018,\n\ttitle = {Soils beneath different arctic shrubs have contrasting responses to a natural gradient in temperature},\n\tvolume = {9},\n\tcopyright = {© 2018 The Authors.},\n\tissn = {2150-8925},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecs2.2290},\n\tdoi = {10.1002/ecs2.2290},\n\tabstract = {Shrubs commonly form islands of fertility and are expanding their distribution and dominance in the arctic due to climate change, yet how soil properties may be influenced when different species of shrubs expand under warmer climates remains less explored. Important plant traits, such as their associated root community, are linked to functionally different and dominant shrub species in the arctic and these traits likely shape biogeochemical cycling in areas of shrub expansion. Using an elevational gradient as a proxy for warming, we explored how biochemical processes beneath two important arctic shrubs varied under warmer (low elevation) and cooler (high elevation) climates. Interestingly, the influence of elevation on biogeochemistry varied between the two shrubs. At the low elevation, Betula nana L., an ectomycorrhizal shrub, had high carbon (C) degrading enzyme activities, and relatively low potential net nitrogen (N) mineralization rates. Conversely, Empetrum nigrum ssp. hermaphroditum Hagerup, an ericoid mycorrhizal dwarf-shrub, had higher enzyme activities and net N immobilization rates at the higher elevation. Further, E. nigrum ssp. hermpahroditum appeared to have a more closed C and nutrient cycle than B. nana—enzymes degrading C, N, and phosphorus were tightly correlated with each other and with total C and ammonium concentrations in the humus beneath E. nigrum ssp. hermaphroditum, but not beneath B. nana. Our results suggest differences in the warming responses of C and N cycling beneath shrub species across an arctic tundra landscape.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2019-11-05},\n\tjournal = {Ecosphere},\n\tauthor = {Zhao, Qiong and Sundqvist, Maja K. and Newman, Gregory S. and Classen, Aimée T.},\n\tyear = {2018},\n\tkeywords = {\\#nosource, biochemical processes, ectomycorrhizae, ericoid mycorrhizae, global warming, shrub species},\n\tpages = {e02290},\n}\n\n\n\n\n\n Shrubs commonly form islands of fertility and are expanding their distribution and dominance in the arctic due to climate change, yet how soil properties may be influenced when different species of shrubs expand under warmer climates remains less explored. Important plant traits, such as their associated root community, are linked to functionally different and dominant shrub species in the arctic and these traits likely shape biogeochemical cycling in areas of shrub expansion. Using an elevational gradient as a proxy for warming, we explored how biochemical processes beneath two important arctic shrubs varied under warmer (low elevation) and cooler (high elevation) climates. Interestingly, the influence of elevation on biogeochemistry varied between the two shrubs. At the low elevation, Betula nana L., an ectomycorrhizal shrub, had high carbon (C) degrading enzyme activities, and relatively low potential net nitrogen (N) mineralization rates. Conversely, Empetrum nigrum ssp. hermaphroditum Hagerup, an ericoid mycorrhizal dwarf-shrub, had higher enzyme activities and net N immobilization rates at the higher elevation. Further, E. nigrum ssp. hermpahroditum appeared to have a more closed C and nutrient cycle than B. nana—enzymes degrading C, N, and phosphorus were tightly correlated with each other and with total C and ammonium concentrations in the humus beneath E. nigrum ssp. hermaphroditum, but not beneath B. nana. Our results suggest differences in the warming responses of C and N cycling beneath shrub species across an arctic tundra landscape.\n
\n\n\n\n \n\n \n \n \n \n \n \n Roughness effects of diatomaceous slime fouling on turbulent boundary layer hydrodynamics.\n \n \n \n \n\n\n \n Murphy, E. A. K.; Barros, J. M.; Schultz, M. P.; Flack, K. A.; Steppe, C. N.; and Reidenbach, M. A.\n\n\n \n\n\n\n Biofouling, 34(9): 976–988. October 2018.\n \n\n\n\n
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\n\n\n@article{murphy_roughness_2018,\n\ttitle = {Roughness effects of diatomaceous slime fouling on turbulent boundary layer hydrodynamics},\n\tvolume = {34},\n\tissn = {0892-7014},\n\turl = {https://doi.org/10.1080/08927014.2018.1517867},\n\tdoi = {10.1080/08927014.2018.1517867},\n\tabstract = {Biofilm fouling significantly impacts ship performance. Here, the impact of biofilm on boundary layer structure at a ship-relevant, low Reynolds number was investigated. Boundary layer measurements were performed over slime-fouled plates using high resolution particle image velocimetry (PIV). The velocity profile over the biofilm showed a downward shift in the log-law region (ΔU+), resulting in an effective roughness height (ks) of 8.8 mm, significantly larger than the physical thickness of the biofilm (1.7 ± 0.5 mm) and generating more than three times as much frictional drag as the smooth-wall. The skin-friction coefficient, Cf, of the biofilm was 9.0 × 10−3 compared with 2.9 × 10−3 for the smooth wall. The biofilm also enhances turbulent kinetic energy (tke) and Reynolds shear stress, which are more heterogeneous in the streamwise direction than smooth-wall flows. This suggests that biofilms increase drag due to high levels of momentum transport, likely resulting from protruding streamers and surface compliance.},\n\tnumber = {9},\n\turldate = {2019-07-16},\n\tjournal = {Biofouling},\n\tauthor = {Murphy, Elizabeth A. K. and Barros, Julio M. and Schultz, Michael P. and Flack, Karen A. and Steppe, Cecily N. and Reidenbach, Matthew A.},\n\tmonth = oct,\n\tyear = {2018},\n\tpmid = {30602310},\n\tkeywords = {\\#nosource, Biofilm, PIV, boundary layer, drag, roughness, turbulence},\n\tpages = {976--988},\n}\n\n\n\n\n\n Biofilm fouling significantly impacts ship performance. Here, the impact of biofilm on boundary layer structure at a ship-relevant, low Reynolds number was investigated. Boundary layer measurements were performed over slime-fouled plates using high resolution particle image velocimetry (PIV). The velocity profile over the biofilm showed a downward shift in the log-law region (ΔU+), resulting in an effective roughness height (ks) of 8.8 mm, significantly larger than the physical thickness of the biofilm (1.7 ± 0.5 mm) and generating more than three times as much frictional drag as the smooth-wall. The skin-friction coefficient, Cf, of the biofilm was 9.0 × 10−3 compared with 2.9 × 10−3 for the smooth wall. The biofilm also enhances turbulent kinetic energy (tke) and Reynolds shear stress, which are more heterogeneous in the streamwise direction than smooth-wall flows. This suggests that biofilms increase drag due to high levels of momentum transport, likely resulting from protruding streamers and surface compliance.\n
\n\n\n\n \n\n \n \n \n \n \n \n A song of ice and mud : Interactions of microbes with roots, fauna and carbon in warming permafrost-affected soils.\n \n \n \n \n\n\n \n Monteux, S.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2018.\n \n\n\n\n
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\n\n\n@phdthesis{monteux_song_2018,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {A song of ice and mud : {Interactions} of microbes with roots, fauna and carbon in warming permafrost-affected soils},\n\tshorttitle = {A song of ice and mud},\n\turl = {http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-151472},\n\tabstract = {Permafrost-affected soils store a large quantity of soil organic matter (SOM) – ca. half of worldwide soil carbon – and currently undergo rapid and severe warming due to climate change. Increased SOM decomposition by microorganisms and soil fauna due to climate change, poses the risk of a positive climate feedback through the release of greenhouse gases. Direct effects of climate change on SOM decomposition, through such mechanisms as deepening of the seasonally-thawing active layer and increasing soil temperatures, have gathered considerable scientific attention in the last two decades. Yet, indirect effects mediated by changes in plant, microbial, and fauna communities, remain poorly understood. Microbial communities, which may be affected by climate change-induced changes in vegetation composition or rooting patterns, and may in turn affect SOM decomposition, are the primary focus of the work described in this thesis.\n\nWe used (I) a field-scale permafrost thaw experiment in a palsa peatland, (II) a laboratory incubation of Yedoma permafrost with inoculation by exotic microorganisms, (III) a microcosm experiment with five plant species grown either in Sphagnum peat or in newly-thawed permafrost peat, and (IV) a field-scale cold season warming experiment in cryoturbated tundra to address the indirect effects of climate change on microbial drivers of SOM decomposition. Community composition data for bacteria and fungi were obtained by amplicon sequencing and phospholipid fatty acid extraction, and for collembola by Tullgren extraction, alongside measurements of soil chemistry, CO2 emissions and root density.\n\nWe showed that in situ thawing of a palsa peatland caused colonization of permafrost soil by overlying soil microbes. Further, we observed that functional limitations of permafrost microbial communities can hamper microbial metabolism in vitro. Relieving these functional limitations in vitro increased cumulative CO2 emissions by 32\\% over 161 days and introduced nitrification. In addition, we found that different plant species did not harbour different rhizosphere bacterial communities in Sphagnum peat topsoil, but did when grown in newly-thawed permafrost peat. Plant species may thus differ in how they affect functional limitations in thawing permafrost soil. Therefore, climate change-induced changes in vegetation composition might alter functioning in the newly-thawed, subsoil permafrost layer of northern peatlands, but less likely so in the topsoil. Finally, we observed that vegetation encroachment in barren cryoturbated soil, due to reduced cryogenic activity with higher temperatures, change both bacterial and collembola community composition, which may in turn affect soil functioning.\n\nThis thesis shows that microbial community dynamics and plant-decomposer interactions play an important role in the functioning of warming permafrost-affected soils. More specifically, it demonstrates that the effects of climate change on plants can trickle down on microbial communities, in turn affecting SOM decomposition in thawing permafrost.},\n\tlanguage = {eng},\n\turldate = {2018-09-12},\n\tschool = {Umeå University},\n\tauthor = {Monteux, Sylvain},\n\tcollaborator = {Dorrepaal, Ellen and Keuper, Frida and Weedon, James T.},\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Permafrost-affected soils store a large quantity of soil organic matter (SOM) – ca. half of worldwide soil carbon – and currently undergo rapid and severe warming due to climate change. Increased SOM decomposition by microorganisms and soil fauna due to climate change, poses the risk of a positive climate feedback through the release of greenhouse gases. Direct effects of climate change on SOM decomposition, through such mechanisms as deepening of the seasonally-thawing active layer and increasing soil temperatures, have gathered considerable scientific attention in the last two decades. Yet, indirect effects mediated by changes in plant, microbial, and fauna communities, remain poorly understood. Microbial communities, which may be affected by climate change-induced changes in vegetation composition or rooting patterns, and may in turn affect SOM decomposition, are the primary focus of the work described in this thesis. We used (I) a field-scale permafrost thaw experiment in a palsa peatland, (II) a laboratory incubation of Yedoma permafrost with inoculation by exotic microorganisms, (III) a microcosm experiment with five plant species grown either in Sphagnum peat or in newly-thawed permafrost peat, and (IV) a field-scale cold season warming experiment in cryoturbated tundra to address the indirect effects of climate change on microbial drivers of SOM decomposition. Community composition data for bacteria and fungi were obtained by amplicon sequencing and phospholipid fatty acid extraction, and for collembola by Tullgren extraction, alongside measurements of soil chemistry, CO2 emissions and root density. We showed that in situ thawing of a palsa peatland caused colonization of permafrost soil by overlying soil microbes. Further, we observed that functional limitations of permafrost microbial communities can hamper microbial metabolism in vitro. Relieving these functional limitations in vitro increased cumulative CO2 emissions by 32% over 161 days and introduced nitrification. In addition, we found that different plant species did not harbour different rhizosphere bacterial communities in Sphagnum peat topsoil, but did when grown in newly-thawed permafrost peat. Plant species may thus differ in how they affect functional limitations in thawing permafrost soil. Therefore, climate change-induced changes in vegetation composition might alter functioning in the newly-thawed, subsoil permafrost layer of northern peatlands, but less likely so in the topsoil. Finally, we observed that vegetation encroachment in barren cryoturbated soil, due to reduced cryogenic activity with higher temperatures, change both bacterial and collembola community composition, which may in turn affect soil functioning. This thesis shows that microbial community dynamics and plant-decomposer interactions play an important role in the functioning of warming permafrost-affected soils. More specifically, it demonstrates that the effects of climate change on plants can trickle down on microbial communities, in turn affecting SOM decomposition in thawing permafrost.\n
\n\n\n\n \n\n \n \n \n \n \n \n Interaction strength and stability in stage-structured food web modules.\n \n \n \n \n\n\n \n Nilsson, K. A.; McCann, K. S.; and Caskenette, A. L.\n\n\n \n\n\n\n Oikos, 127(10): 1494–1505. April 2018.\n 00000\n\n\n\n
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\n\n\n@article{nilsson_interaction_2018,\n\ttitle = {Interaction strength and stability in stage-structured food web modules},\n\tvolume = {127},\n\tcopyright = {© 2018 The Authors},\n\tissn = {1600-0706},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.05029},\n\tdoi = {10.1111/oik.05029},\n\tabstract = {There has been a long-standing debate on what creates stability in food webs. One major finding is that weak interactions can mute the destabilizing potential of strong interactions. Considering that stage structure is common in nature, that existing studies on stability that include population stage structure point in different directions, and the recent theoretical developments in the area of stage structure, there is a need to address the effects of population stage structure in this context. Using simple food web modules, with stage structure in an intermediate consumer, we here begin to theoretically investigate the effects of stage structure on food web stability. We found a general correspondence to previous results such that strong interactions had destabilizing effects and weak interactions that result in decreased energy flux had stabilizing effects. However, we also found a number of novel results connected to stage structure. Interestingly, weak interactions can be destabilizing when they excite other interactions. We also found that cohort cycles and predator–prey cycles did not respond in the same way to increasing interactions strength. We found that the combined effects of two predators feeding on the same prey can strongly destabilize a system. Consistent with previous studies, we also found that stage-specific feeding can create a refuge effect that leads to a lack of strong destabilization at high interaction strength. Overall, stage structure had both stabilizing and destabilizing aspects. Some effects could be explained by our current understanding of energetic processes; others need additional consideration. Additional aspects such as shunting of energy between stages, control of biomass fluxes, and interactions between lags and energy flux, should be considered.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2018-07-05},\n\tjournal = {Oikos},\n\tauthor = {Nilsson, Karin A. and McCann, Kevin S. and Caskenette, Amanda L.},\n\tmonth = apr,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, interaction strength, stability, stage structure},\n\tpages = {1494--1505},\n}\n\n\n\n\n\n There has been a long-standing debate on what creates stability in food webs. One major finding is that weak interactions can mute the destabilizing potential of strong interactions. Considering that stage structure is common in nature, that existing studies on stability that include population stage structure point in different directions, and the recent theoretical developments in the area of stage structure, there is a need to address the effects of population stage structure in this context. Using simple food web modules, with stage structure in an intermediate consumer, we here begin to theoretically investigate the effects of stage structure on food web stability. We found a general correspondence to previous results such that strong interactions had destabilizing effects and weak interactions that result in decreased energy flux had stabilizing effects. However, we also found a number of novel results connected to stage structure. Interestingly, weak interactions can be destabilizing when they excite other interactions. We also found that cohort cycles and predator–prey cycles did not respond in the same way to increasing interactions strength. We found that the combined effects of two predators feeding on the same prey can strongly destabilize a system. Consistent with previous studies, we also found that stage-specific feeding can create a refuge effect that leads to a lack of strong destabilization at high interaction strength. Overall, stage structure had both stabilizing and destabilizing aspects. Some effects could be explained by our current understanding of energetic processes; others need additional consideration. Additional aspects such as shunting of energy between stages, control of biomass fluxes, and interactions between lags and energy flux, should be considered.\n
\n\n\n\n \n\n \n \n \n \n \n \n Short and Long-Term Controls on Active Layer and Permafrost Carbon Turnover Across the Arctic.\n \n \n \n \n\n\n \n Faucherre, S.; Jørgensen, C. J.; Blok, D.; Weiss, N.; Siewert, M. B.; Bang‐Andreasen, T.; Hugelius, G.; Kuhry, P.; and Elberling, B.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 123(2): 372–390. February 2018.\n 00002\n\n\n\n
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\n\n\n@article{faucherre_short_2018,\n\ttitle = {Short and {Long}-{Term} {Controls} on {Active} {Layer} and {Permafrost} {Carbon} {Turnover} {Across} the {Arctic}},\n\tvolume = {123},\n\tcopyright = {©2018. American Geophysical Union. All Rights Reserved.},\n\tissn = {2169-8961},\n\turl = {http://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JG004069},\n\tdoi = {10.1002/2017JG004069},\n\tabstract = {Decomposition of soil organic matter (SOM) in permafrost terrain and the production of greenhouse gases is a key factor for understanding climate change-carbon feedbacks. Previous studies have shown that SOM decomposition is mostly controlled by soil temperature, soil moisture, and carbon-nitrogen ratio (C:N). However, focus has generally been on site-specific processes and little is known about variations in the controls on SOM decomposition across Arctic sites. For assessing SOM decomposition, we retrieved 241 samples from 101 soil profiles across three contrasting Arctic regions and incubated them in the laboratory under aerobic conditions. We assessed soil carbon losses (Closs) five times during a 1 year incubation. The incubated material consisted of near-surface active layer (ALNS), subsurface active layer (ALSS), peat, and permafrost samples. Samples were analyzed for carbon, nitrogen, water content, δ13C, δ15N, and dry bulk density (DBD). While no significant differences were observed between total ALSS and permafrost Closs over 1 year incubation (2.3 ± 2.4\\% and 2.5 ± 1.5\\% Closs, respectively), ALNS samples showed higher Closs (7.9 ± 4.2\\%). DBD was the best explanatory parameter for active layer Closs across sites. Additionally, results of permafrost samples show that C:N ratio can be used to characterize initial Closs between sites. This data set on the influence of abiotic parameter on microbial SOM decomposition can improve model simulations of Arctic soil CO2 production by providing representative mean values of CO2 production rates and identifying standard parameters or proxies for upscaling potential CO2 production from site to regional scales.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2018-08-30},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Faucherre, Samuel and Jørgensen, Christian Juncher and Blok, Daan and Weiss, Niels and Siewert, Matthias Benjamin and Bang‐Andreasen, Toke and Hugelius, Gustaf and Kuhry, Peter and Elberling, Bo},\n\tmonth = feb,\n\tyear = {2018},\n\tnote = {00002},\n\tkeywords = {\\#nosource, carbon, carbon dioxide, carbon mineralization, decomposition, permafrost},\n\tpages = {372--390},\n}\n\n\n\n\n\n Decomposition of soil organic matter (SOM) in permafrost terrain and the production of greenhouse gases is a key factor for understanding climate change-carbon feedbacks. Previous studies have shown that SOM decomposition is mostly controlled by soil temperature, soil moisture, and carbon-nitrogen ratio (C:N). However, focus has generally been on site-specific processes and little is known about variations in the controls on SOM decomposition across Arctic sites. For assessing SOM decomposition, we retrieved 241 samples from 101 soil profiles across three contrasting Arctic regions and incubated them in the laboratory under aerobic conditions. We assessed soil carbon losses (Closs) five times during a 1 year incubation. The incubated material consisted of near-surface active layer (ALNS), subsurface active layer (ALSS), peat, and permafrost samples. Samples were analyzed for carbon, nitrogen, water content, δ13C, δ15N, and dry bulk density (DBD). While no significant differences were observed between total ALSS and permafrost Closs over 1 year incubation (2.3 ± 2.4% and 2.5 ± 1.5% Closs, respectively), ALNS samples showed higher Closs (7.9 ± 4.2%). DBD was the best explanatory parameter for active layer Closs across sites. Additionally, results of permafrost samples show that C:N ratio can be used to characterize initial Closs between sites. This data set on the influence of abiotic parameter on microbial SOM decomposition can improve model simulations of Arctic soil CO2 production by providing representative mean values of CO2 production rates and identifying standard parameters or proxies for upscaling potential CO2 production from site to regional scales.\n
\n\n\n\n \n\n \n \n \n \n \n \n High-resolution digital mapping of soil organic carbon in permafrost terrain using machine learning : a case study in a sub-Arctic peatland environment.\n \n \n \n \n\n\n \n Siewert, M. B.\n\n\n \n\n\n\n Biogeosciences, 15(6): 1663–1682. 2018.\n 00002\n\n\n\n
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\n\n\n\n@article{siewert_high-resolution_2018,\n\ttitle = {High-resolution digital mapping of soil organic carbon in permafrost terrain using machine learning : a case study in a sub-{Arctic} peatland environment},\n\tvolume = {15},\n\tshorttitle = {High-resolution digital mapping of soil organic carbon in permafrost terrain using machine learning},\n\turl = {http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-146566},\n\tdoi = {10.5194/bg-15-1663-2018},\n\tlanguage = {eng},\n\tnumber = {6},\n\turldate = {2018-08-30},\n\tjournal = {Biogeosciences},\n\tauthor = {Siewert, Matthias B.},\n\tyear = {2018},\n\tnote = {00002},\n\tkeywords = {\\#nosource},\n\tpages = {1663--1682},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Drivers of dissolved organic carbon export in a subarctic catchment: Importance of microbial decomposition, sorption-desorption, peatland and lateral flow.\n \n \n \n \n\n\n \n Tang, J.; Yurova, A. Y.; Schurgers, G.; Miller, P. A.; Olin, S.; Smith, B.; Siewert, M. B.; Olefeldt, D.; Pilesjö, P.; and Poska, A.\n\n\n \n\n\n\n Science of The Total Environment, 622-623: 260–274. May 2018.\n 00001\n\n\n\n
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\n\n\n@article{tang_drivers_2018,\n\ttitle = {Drivers of dissolved organic carbon export in a subarctic catchment: {Importance} of microbial decomposition, sorption-desorption, peatland and lateral flow},\n\tvolume = {622-623},\n\tissn = {0048-9697},\n\tshorttitle = {Drivers of dissolved organic carbon export in a subarctic catchment},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0048969717333107},\n\tdoi = {10.1016/j.scitotenv.2017.11.252},\n\tabstract = {Tundra soils account for 50\\% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.},\n\turldate = {2018-08-30},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Tang, Jing and Yurova, Alla Y. and Schurgers, Guy and Miller, Paul A. and Olin, Stefan and Smith, Benjamin and Siewert, Matthias B. and Olefeldt, David and Pilesjö, Petter and Poska, Anneli},\n\tmonth = may,\n\tyear = {2018},\n\tnote = {00001},\n\tkeywords = {\\#nosource, DOC flux, LPJ-GUESS, Lateral flow, Peatland, Sorption-desorption, Subarctic catchment},\n\tpages = {260--274},\n}\n\n\n\n\n\n Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon dioxide stimulates lake primary production.\n \n \n \n \n\n\n \n Hamdan, M.; Byström, P.; Hotchkiss, E. R.; Al-Haidarey, M. J.; Ask, J.; and Karlsson, J.\n\n\n \n\n\n\n Scientific Reports, 8(1): 10878. July 2018.\n 00000\n\n\n\n
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\n\n\n@article{hamdan_carbon_2018,\n\ttitle = {Carbon dioxide stimulates lake primary production},\n\tvolume = {8},\n\tcopyright = {2018 The Author(s)},\n\tissn = {2045-2322},\n\turl = {http://www.nature.com/articles/s41598-018-29166-3},\n\tdoi = {10.1038/s41598-018-29166-3},\n\tabstract = {Gross primary production (GPP) is a fundamental ecosystem process that sequesters carbon dioxide (CO2) and forms the resource base for higher trophic levels. Still, the relative contribution of different controls on GPP at the whole-ecosystem scale is far from resolved. Here we show, by manipulating CO2 concentrations in large-scale experimental pond ecosystems, that CO2 availability is a key driver of whole-ecosystem GPP. This result suggests we need to reformulate past conceptual models describing controls of lake ecosystem productivity and include our findings when developing models used to predict future lake ecosystem responses to environmental change.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-07-30},\n\tjournal = {Scientific Reports},\n\tauthor = {Hamdan, Mohammed and Byström, Pär and Hotchkiss, Erin R. and Al-Haidarey, Mohammed J. and Ask, Jenny and Karlsson, Jan},\n\tmonth = jul,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {10878},\n}\n\n\n\n\n\n Gross primary production (GPP) is a fundamental ecosystem process that sequesters carbon dioxide (CO2) and forms the resource base for higher trophic levels. Still, the relative contribution of different controls on GPP at the whole-ecosystem scale is far from resolved. Here we show, by manipulating CO2 concentrations in large-scale experimental pond ecosystems, that CO2 availability is a key driver of whole-ecosystem GPP. This result suggests we need to reformulate past conceptual models describing controls of lake ecosystem productivity and include our findings when developing models used to predict future lake ecosystem responses to environmental change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dissolved organic carbon in streams within a subarctic catchment analysed using a GIS/remote sensing approach.\n \n \n \n \n\n\n \n Mzobe, P.; Berggren, M.; Pilesjö, P.; Lundin, E.; Olefeldt, D.; Roulet, N. T.; and Persson, A.\n\n\n \n\n\n\n PLOS ONE, 13(7): e0199608. July 2018.\n 00000\n\n\n\n
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\n\n\n@article{mzobe_dissolved_2018,\n\ttitle = {Dissolved organic carbon in streams within a subarctic catchment analysed using a {GIS}/remote sensing approach},\n\tvolume = {13},\n\tissn = {1932-6203},\n\turl = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0199608},\n\tdoi = {10.1371/journal.pone.0199608},\n\tabstract = {Climate change projections show that temperature and precipitation increases can alter the exchange of greenhouse gases between the atmosphere and high latitude landscapes, including their freshwaters. Dissolved organic carbon (DOC) plays an important role in greenhouse gas emissions, but the impact of catchment productivity on DOC release to subarctic waters remains poorly known, especially at regional scales. We test the hypothesis that increased terrestrial productivity, as indicated by the normalized difference vegetation index (NDVI), generates higher stream DOC concentrations in the Stordalen catchment in subarctic Sweden. Furthermore, we aimed to determine the degree to which other generic catchment properties (elevation, slope) explain DOC concentration, and whether or not land cover variables representing the local vegetation type (e.g., mire, forest) need to be included to obtain adequate predictive models for DOC delivered into rivers. We show that the land cover type, especially the proportion of mire, played a dominant role in the catchment’s release of DOC, while NDVI, slope, and elevation were supporting predictor variables. The NDVI as a single predictor showed weak and inconsistent relationships to DOC concentrations in recipient waters, yet NDVI was a significant positive regulator of DOC in multiple regression models that included land cover variables. Our study illustrates that vegetation type exerts primary control in DOC regulation in Stordalen, while productivity (NDVI) is of secondary importance. Thus, predictive multiple linear regression models for DOC can be utilized combining these different types of explanatory variables.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2018-07-16},\n\tjournal = {PLOS ONE},\n\tauthor = {Mzobe, Pearl and Berggren, Martin and Pilesjö, Petter and Lundin, Erik and Olefeldt, David and Roulet, Nigel T. and Persson, Andreas},\n\tmonth = jul,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Climate change, Forests, Lakes, Linear regression analysis, Rivers, Surface water, Tundra, Wetlands},\n\tpages = {e0199608},\n}\n\n\n\n\n\n Climate change projections show that temperature and precipitation increases can alter the exchange of greenhouse gases between the atmosphere and high latitude landscapes, including their freshwaters. Dissolved organic carbon (DOC) plays an important role in greenhouse gas emissions, but the impact of catchment productivity on DOC release to subarctic waters remains poorly known, especially at regional scales. We test the hypothesis that increased terrestrial productivity, as indicated by the normalized difference vegetation index (NDVI), generates higher stream DOC concentrations in the Stordalen catchment in subarctic Sweden. Furthermore, we aimed to determine the degree to which other generic catchment properties (elevation, slope) explain DOC concentration, and whether or not land cover variables representing the local vegetation type (e.g., mire, forest) need to be included to obtain adequate predictive models for DOC delivered into rivers. We show that the land cover type, especially the proportion of mire, played a dominant role in the catchment’s release of DOC, while NDVI, slope, and elevation were supporting predictor variables. The NDVI as a single predictor showed weak and inconsistent relationships to DOC concentrations in recipient waters, yet NDVI was a significant positive regulator of DOC in multiple regression models that included land cover variables. Our study illustrates that vegetation type exerts primary control in DOC regulation in Stordalen, while productivity (NDVI) is of secondary importance. Thus, predictive multiple linear regression models for DOC can be utilized combining these different types of explanatory variables.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global drivers of tree seedling establishment at alpine treelines in a changing climate.\n \n \n \n \n\n\n \n Lett, S.; and Dorrepaal, E.\n\n\n \n\n\n\n Functional Ecology, 32(7): 1666–1680. 2018.\n 00000\n\n\n\n
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\n\n\n@article{lett_global_2018,\n\ttitle = {Global drivers of tree seedling establishment at alpine treelines in a changing climate},\n\tvolume = {32},\n\tcopyright = {© 2018 The Authors. Functional Ecology © 2018 British Ecological Society},\n\tissn = {1365-2435},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2435.13137},\n\tdoi = {10.1111/1365-2435.13137},\n\tabstract = {Alpine and Arctic treeline expansion depends on establishment of tree seedlings beyond the current treeline, which is expected to occur with climate warming. However, treelines often fail to respond to higher temperatures, and it is therefore likely that other environmental factors are important for seedling establishment. We aimed to analyse our current understanding of how temperature and a range of other environmental drivers affect tree seedling establishment at the alpine and Arctic treelines world-wide and to assess the relative importance of temperature compared with other factors and how they interact. We collected 366 observations from 76 experimental and observational papers for a qualitative analysis of the role of a wide range of environmental factors on tree seed germination, tree seedling growth, survival and natural occurrence. For a subset of these studies, where the experimental design allowed, we conducted formal meta-analyses to reveal if there were global drivers for different seedling life traits. The analyses showed that a wide range of abiotic and biotic factors affected tree seedling establishment besides from temperature, including water, snow, nutrients, light and surrounding vegetation. The meta-analyses showed that different seedling life stages do not respond similarly to environmental factors. For example, temperature had positive effects on growth, while tree seedling survival and germination showed mixed responses to warming. Further, warming was as often as not the strongest factor controlling tree seedling establishment, when compared to with one of five other environmental factors. Moreover, warming effects often depended on other factors such as moisture or the presence of surrounding vegetation. Our results suggest that population dynamics of trees at the alpine and Arctic treeline is responsive to environmental changes and show that there is a clear need for multifactorial studies if we want to fully understand and predict the interplay between warming and other environmental factors and their effect on tree seedling establishment across current treelines. A plain language summary is available for this article.},\n\tnumber = {7},\n\turldate = {2018-07-05},\n\tjournal = {Functional Ecology},\n\tauthor = {Lett, Signe and Dorrepaal, Ellen},\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, germination, growth, nutrients, plant interactions, snow, soil moisture, survival, warming},\n\tpages = {1666--1680},\n}\n\n\n\n\n\n Alpine and Arctic treeline expansion depends on establishment of tree seedlings beyond the current treeline, which is expected to occur with climate warming. However, treelines often fail to respond to higher temperatures, and it is therefore likely that other environmental factors are important for seedling establishment. We aimed to analyse our current understanding of how temperature and a range of other environmental drivers affect tree seedling establishment at the alpine and Arctic treelines world-wide and to assess the relative importance of temperature compared with other factors and how they interact. We collected 366 observations from 76 experimental and observational papers for a qualitative analysis of the role of a wide range of environmental factors on tree seed germination, tree seedling growth, survival and natural occurrence. For a subset of these studies, where the experimental design allowed, we conducted formal meta-analyses to reveal if there were global drivers for different seedling life traits. The analyses showed that a wide range of abiotic and biotic factors affected tree seedling establishment besides from temperature, including water, snow, nutrients, light and surrounding vegetation. The meta-analyses showed that different seedling life stages do not respond similarly to environmental factors. For example, temperature had positive effects on growth, while tree seedling survival and germination showed mixed responses to warming. Further, warming was as often as not the strongest factor controlling tree seedling establishment, when compared to with one of five other environmental factors. Moreover, warming effects often depended on other factors such as moisture or the presence of surrounding vegetation. Our results suggest that population dynamics of trees at the alpine and Arctic treeline is responsive to environmental changes and show that there is a clear need for multifactorial studies if we want to fully understand and predict the interplay between warming and other environmental factors and their effect on tree seedling establishment across current treelines. A plain language summary is available for this article.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant functional trait change across a warming tundra biome.\n \n \n \n \n\n\n \n Bjorkman, A. D.; Myers-Smith, I. H.; Elmendorf, S. C.; Normand, S.; Rüger, N.; Beck, P. S. A.; Blach-Overgaard, A.; Blok, D.; Cornelissen, J. H. C.; Forbes, B. C.; Georges, D.; Goetz, S. J.; Guay, K. C.; Henry, G. H. R.; HilleRisLambers, J.; Hollister, R. D.; Karger, D. N.; Kattge, J.; Manning, P.; Prevéy, J. S.; Rixen, C.; Schaepman-Strub, G.; Thomas, H. J. D.; Vellend, M.; Wilmking, M.; Wipf, S.; Carbognani, M.; Hermanutz, L.; Lévesque, E.; Molau, U.; Petraglia, A.; Soudzilovskaia, N. A.; Spasojevic, M. J.; Tomaselli, M.; Vowles, T.; Alatalo, J. M.; Alexander, H. D.; Anadon-Rosell, A.; Angers-Blondin, S.; Beest, M. t.; Berner, L.; Björk, R. G.; Buchwal, A.; Buras, A.; Christie, K.; Cooper, E. J.; Dullinger, S.; Elberling, B.; Eskelinen, A.; Frei, E. R.; Grau, O.; Grogan, P.; Hallinger, M.; Harper, K. A.; Heijmans, M. M. P. D.; Hudson, J.; Hülber, K.; Iturrate-Garcia, M.; Iversen, C. M.; Jaroszynska, F.; Johnstone, J. F.; Jørgensen, R. H.; Kaarlejärvi, E.; Klady, R.; Kuleza, S.; Kulonen, A.; Lamarque, L. J.; Lantz, T.; Little, C. J.; Speed, J. D. M.; Michelsen, A.; Milbau, A.; Nabe-Nielsen, J.; Nielsen, S. S.; Ninot, J. M.; Oberbauer, S. F.; Olofsson, J.; Onipchenko, V. G.; Rumpf, S. B.; Semenchuk, P.; Shetti, R.; Collier, L. S.; Street, L. E.; Suding, K. N.; Tape, K. D.; Trant, A.; Treier, U. A.; Tremblay, J.; Tremblay, M.; Venn, S.; Weijers, S.; Zamin, T.; Boulanger-Lapointe, N.; Gould, W. A.; Hik, D. S.; Hofgaard, A.; Jónsdóttir, I. S.; Jorgenson, J.; Klein, J.; Magnusson, B.; Tweedie, C.; Wookey, P. A.; Bahn, M.; Blonder, B.; Bodegom, P. M. v.; Bond-Lamberty, B.; Campetella, G.; Cerabolini, B. E. L.; Chapin, F. S.; Cornwell, W. K.; Craine, J.; Dainese, M.; Vries, F. T. d.; Díaz, S.; Enquist, B. J.; Green, W.; Milla, R.; Niinemets, Ü.; Onoda, Y.; Ordoñez, J. C.; Ozinga, W. A.; Penuelas, J.; Poorter, H.; Poschlod, P.; Reich, P. B.; Sandel, B.; Schamp, B.; Sheremetev, S.; and Weiher, E.\n\n\n \n\n\n\n Nature, 562(7725): 57. October 2018.\n \n\n\n\n
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\n\n\n@article{bjorkman_plant_2018,\n\ttitle = {Plant functional trait change across a warming tundra biome},\n\tvolume = {562},\n\tcopyright = {2018 Springer Nature Limited},\n\tissn = {1476-4687},\n\turl = {https://www.nature.com/articles/s41586-018-0563-7},\n\tdoi = {10.1038/s41586-018-0563-7},\n\tabstract = {Analyses of the relationships between temperature, moisture and seven key plant functional traits across the tundra and over time show that community height increased with warming across all sites, whereas other traits lagged behind predicted rates of change.},\n\tlanguage = {En},\n\tnumber = {7725},\n\turldate = {2018-10-25},\n\tjournal = {Nature},\n\tauthor = {Bjorkman, Anne D. and Myers-Smith, Isla H. and Elmendorf, Sarah C. and Normand, Signe and Rüger, Nadja and Beck, Pieter S. A. and Blach-Overgaard, Anne and Blok, Daan and Cornelissen, J. Hans C. and Forbes, Bruce C. and Georges, Damien and Goetz, Scott J. and Guay, Kevin C. and Henry, Gregory H. R. and HilleRisLambers, Janneke and Hollister, Robert D. and Karger, Dirk N. and Kattge, Jens and Manning, Peter and Prevéy, Janet S. and Rixen, Christian and Schaepman-Strub, Gabriela and Thomas, Haydn J. D. and Vellend, Mark and Wilmking, Martin and Wipf, Sonja and Carbognani, Michele and Hermanutz, Luise and Lévesque, Esther and Molau, Ulf and Petraglia, Alessandro and Soudzilovskaia, Nadejda A. and Spasojevic, Marko J. and Tomaselli, Marcello and Vowles, Tage and Alatalo, Juha M. and Alexander, Heather D. and Anadon-Rosell, Alba and Angers-Blondin, Sandra and Beest, Mariska te and Berner, Logan and Björk, Robert G. and Buchwal, Agata and Buras, Allan and Christie, Katherine and Cooper, Elisabeth J. and Dullinger, Stefan and Elberling, Bo and Eskelinen, Anu and Frei, Esther R. and Grau, Oriol and Grogan, Paul and Hallinger, Martin and Harper, Karen A. and Heijmans, Monique M. P. D. and Hudson, James and Hülber, Karl and Iturrate-Garcia, Maitane and Iversen, Colleen M. and Jaroszynska, Francesca and Johnstone, Jill F. and Jørgensen, Rasmus Halfdan and Kaarlejärvi, Elina and Klady, Rebecca and Kuleza, Sara and Kulonen, Aino and Lamarque, Laurent J. and Lantz, Trevor and Little, Chelsea J. and Speed, James D. M. and Michelsen, Anders and Milbau, Ann and Nabe-Nielsen, Jacob and Nielsen, Sigrid Schøler and Ninot, Josep M. and Oberbauer, Steven F. and Olofsson, Johan and Onipchenko, Vladimir G. and Rumpf, Sabine B. and Semenchuk, Philipp and Shetti, Rohan and Collier, Laura Siegwart and Street, Lorna E. and Suding, Katharine N. and Tape, Ken D. and Trant, Andrew and Treier, Urs A. and Tremblay, Jean-Pierre and Tremblay, Maxime and Venn, Susanna and Weijers, Stef and Zamin, Tara and Boulanger-Lapointe, Noémie and Gould, William A. and Hik, David S. and Hofgaard, Annika and Jónsdóttir, Ingibjörg S. and Jorgenson, Janet and Klein, Julia and Magnusson, Borgthor and Tweedie, Craig and Wookey, Philip A. and Bahn, Michael and Blonder, Benjamin and Bodegom, Peter M. van and Bond-Lamberty, Benjamin and Campetella, Giandiego and Cerabolini, Bruno E. L. and Chapin, F. Stuart and Cornwell, William K. and Craine, Joseph and Dainese, Matteo and Vries, Franciska T. de and Díaz, Sandra and Enquist, Brian J. and Green, Walton and Milla, Ruben and Niinemets, Ülo and Onoda, Yusuke and Ordoñez, Jenny C. and Ozinga, Wim A. and Penuelas, Josep and Poorter, Hendrik and Poschlod, Peter and Reich, Peter B. and Sandel, Brody and Schamp, Brandon and Sheremetev, Serge and Weiher, Evan},\n\tmonth = oct,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {57},\n}\n\n\n\n\n\n Analyses of the relationships between temperature, moisture and seven key plant functional traits across the tundra and over time show that community height increased with warming across all sites, whereas other traits lagged behind predicted rates of change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Similarity in spatial structure constrains ecosystem relationships: Building a macroscale understanding of lakes.\n \n \n \n \n\n\n \n Lapierre, J.; Collins, S. M.; Seekell, D. A.; Cheruvelil, K. S.; Tan, P.; Skaff, N. K.; Taranu, Z. E.; Fergus, C. E.; and Soranno, P. A.\n\n\n \n\n\n\n Global Ecology and Biogeography, 27: 1251–1263. September 2018.\n 00000\n\n\n\n
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\n\n\n@article{lapierre_similarity_2018,\n\ttitle = {Similarity in spatial structure constrains ecosystem relationships: {Building} a macroscale understanding of lakes},\n\tvolume = {27},\n\tcopyright = {© 2018 John Wiley \\& Sons Ltd},\n\tissn = {1466-8238},\n\tshorttitle = {Similarity in spatial structure constrains ecosystem relationships},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12781},\n\tdoi = {10.1111/geb.12781},\n\tabstract = {Aim We aimed to measure the dominant spatial patterns in ecosystem properties (such as nutrients and measures of primary production) and the multi-scaled geographical driver variables of these properties and to quantify how the spatial structure of pattern in all of these variables influences the strength of relationships among them. Location and time period: We studied {\\textgreater} 8,500 lakes in a 1.8 million km2 area of Northeast U.S.A. Data comprised 10-year medians (2002–2011) for measured ecosystem properties, long-term climate averages and recent land use/land cover variables. Major taxa studied: We focused on ecosystem properties at the base of aquatic food webs, including concentrations of nutrients and algal pigments that are proxies of primary productivity. Methods We quantified spatial structure in ecosystem properties and their geographical driver variables using distance-based Moran eigenvector maps (dbMEMs). We then compared the similarity in spatial structure for all pairs of variables with the correlation between variables to illustrate how spatial structure constrains relationships among ecosystem properties. Results The strength of spatial structure decreased in order for climate, land cover/use, lake ecosystem properties and lake and landscape morphometry. Having a comparable spatial structure is a necessary condition to observe a strong relationship between a pair of variables, but not a sufficient one; variables with very different spatial structure are never strongly correlated. Lake ecosystem properties tended to have an intermediary spatial structure compared with that of their main drivers, probably because climate and landscape variables with known ecological links induce spatial patterns. Main conclusions:Our empirical results describe inherent spatial constraints that dictate the expected relationships between ecosystem properties and their geographical drivers at macroscales. Our results also suggest that understanding the spatial scales at which ecological processes operate is necessary to predict the effects of multi-scaled environmental changes on ecosystem properties.},\n\tlanguage = {en},\n\turldate = {2018-09-20},\n\tjournal = {Global Ecology and Biogeography},\n\tauthor = {Lapierre, Jean-Francois and Collins, Sarah M. and Seekell, David A. and Cheruvelil, Kendra Spence and Tan, Pang-Ning and Skaff, Nicholas K. and Taranu, Zofia E. and Fergus, C. Emi and Soranno, Patricia A.},\n\tmonth = sep,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Moran eigenvector maps, climate, ecosystem, lake, landscape, macroscales, spatial autocorrelation, spatial scale, spatial structure},\n\tpages = {1251--1263},\n}\n\n\n\n\n\n Aim We aimed to measure the dominant spatial patterns in ecosystem properties (such as nutrients and measures of primary production) and the multi-scaled geographical driver variables of these properties and to quantify how the spatial structure of pattern in all of these variables influences the strength of relationships among them. Location and time period: We studied \\textgreater 8,500 lakes in a 1.8 million km2 area of Northeast U.S.A. Data comprised 10-year medians (2002–2011) for measured ecosystem properties, long-term climate averages and recent land use/land cover variables. Major taxa studied: We focused on ecosystem properties at the base of aquatic food webs, including concentrations of nutrients and algal pigments that are proxies of primary productivity. Methods We quantified spatial structure in ecosystem properties and their geographical driver variables using distance-based Moran eigenvector maps (dbMEMs). We then compared the similarity in spatial structure for all pairs of variables with the correlation between variables to illustrate how spatial structure constrains relationships among ecosystem properties. Results The strength of spatial structure decreased in order for climate, land cover/use, lake ecosystem properties and lake and landscape morphometry. Having a comparable spatial structure is a necessary condition to observe a strong relationship between a pair of variables, but not a sufficient one; variables with very different spatial structure are never strongly correlated. Lake ecosystem properties tended to have an intermediary spatial structure compared with that of their main drivers, probably because climate and landscape variables with known ecological links induce spatial patterns. Main conclusions:Our empirical results describe inherent spatial constraints that dictate the expected relationships between ecosystem properties and their geographical drivers at macroscales. Our results also suggest that understanding the spatial scales at which ecological processes operate is necessary to predict the effects of multi-scaled environmental changes on ecosystem properties.\n
\n\n\n\n \n\n \n \n \n \n \n \n Winter warming effects on tundra shrub performance are species-specific and dependent on spring conditions.\n \n \n \n \n\n\n \n Krab, E. J.; Rönnefarth, J.; Becher, M.; Blume-Werry, G.; Keuper, F.; Klaminder, J.; Kreyling, J.; Makoto, K.; Milbau, A.; and Dorrepaal, E.\n\n\n \n\n\n\n Journal of Ecology, 106: 599–612. 2018.\n 00000\n\n\n\n
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\n\n\n@article{krab_winter_2018,\n\ttitle = {Winter warming effects on tundra shrub performance are species-specific and dependent on spring conditions},\n\tvolume = {106},\n\tissn = {1365-2745},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/1365-2745.12872/abstract},\n\tdoi = {10.1111/1365-2745.12872},\n\tabstract = {1.Climate change driven increases in winter temperatures positively affect conditions for shrub growth in arctic tundra by decreasing plant frost damage and stimulation of nutrient availability. However, the extent to which shrubs may benefit from these conditions may be strongly dependent on the following spring climate. Species-specific differences in phenology and spring frost sensitivity likely affect shrub growth responses to warming. Additionally, effects of changes in winter and spring climate may differ over small spatial scales, as shrub growth may be dependent on natural variation in snow cover, shrub density and cryoturbation. 2.We investigated the effects of winter warming and altered spring climate on growing-season performance of three common and widespread shrub species in cryoturbated non-sorted circle arctic tundra. By insulating sparsely vegetated non-sorted circles and parts of the surrounding heath with additional snow or gardening fleeces we created two climate change scenarios: Snow addition increased soil temperatures in autumn and winter and delayed snowmelt timing without increasing spring temperatures, whereas fleeces increased soil temperature similarly in autumn and winter, but created warmer spring conditions without altering snowmelt timing. 3.Winter warming affected shrub performance, but the direction and magnitude were species-specific and dependent on spring conditions. Spring warming advanced, and later snowmelt delayed canopy green-up. The fleece treatment did not affect shoot growth and biomass in any shrub species despite decreasing leaf frost-damage in E. nigrum. Snow addition decreased frost damage and stimulated growth of V. vitis-idaea by approximately 50\\%, while decreasing in B. nana growth (P {\\textless} 0.1). All of these effects were consistent in the mostly barren circles and surrounding heath. 4.Synthesis. In cryoturbated arctic tundra, growth of V. vitis-idaea may substantially increase when a thicker snow cover delays snowmelt, whereas in longer-term, warmer winters and springs may favor E. nigrum instead. This may affect shrub community composition and cover, with potentially far-reaching effects on arctic ecosystem functioning via its effects on cryoturbation, carbon cycling and trophic cascading. Our results highlight the importance of disentangling effects of winter and spring climate change timing and nature, as spring conditions are a crucial factor in determining the impact of winter warming on plant performance. This article is protected by copyright. All rights reserved.},\n\tlanguage = {en},\n\turldate = {2017-09-26},\n\tjournal = {Journal of Ecology},\n\tauthor = {Krab, Eveline J. and Rönnefarth, Jonas and Becher, Marina and Blume-Werry, Gesche and Keuper, Frida and Klaminder, Jonatan and Kreyling, Juergen and Makoto, Kobayashi and Milbau, Ann and Dorrepaal, Ellen},\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Betula nana, Cryoturbation, Empetrum nigrum, Plant phenology, Vaccinium vitis-idaea, shrubs, snow cover, snowmelt timing, spring climate, winter climate change},\n\tpages = {599--612},\n}\n\n\n\n\n\n 1.Climate change driven increases in winter temperatures positively affect conditions for shrub growth in arctic tundra by decreasing plant frost damage and stimulation of nutrient availability. However, the extent to which shrubs may benefit from these conditions may be strongly dependent on the following spring climate. Species-specific differences in phenology and spring frost sensitivity likely affect shrub growth responses to warming. Additionally, effects of changes in winter and spring climate may differ over small spatial scales, as shrub growth may be dependent on natural variation in snow cover, shrub density and cryoturbation. 2.We investigated the effects of winter warming and altered spring climate on growing-season performance of three common and widespread shrub species in cryoturbated non-sorted circle arctic tundra. By insulating sparsely vegetated non-sorted circles and parts of the surrounding heath with additional snow or gardening fleeces we created two climate change scenarios: Snow addition increased soil temperatures in autumn and winter and delayed snowmelt timing without increasing spring temperatures, whereas fleeces increased soil temperature similarly in autumn and winter, but created warmer spring conditions without altering snowmelt timing. 3.Winter warming affected shrub performance, but the direction and magnitude were species-specific and dependent on spring conditions. Spring warming advanced, and later snowmelt delayed canopy green-up. The fleece treatment did not affect shoot growth and biomass in any shrub species despite decreasing leaf frost-damage in E. nigrum. Snow addition decreased frost damage and stimulated growth of V. vitis-idaea by approximately 50%, while decreasing in B. nana growth (P \\textless 0.1). All of these effects were consistent in the mostly barren circles and surrounding heath. 4.Synthesis. In cryoturbated arctic tundra, growth of V. vitis-idaea may substantially increase when a thicker snow cover delays snowmelt, whereas in longer-term, warmer winters and springs may favor E. nigrum instead. This may affect shrub community composition and cover, with potentially far-reaching effects on arctic ecosystem functioning via its effects on cryoturbation, carbon cycling and trophic cascading. Our results highlight the importance of disentangling effects of winter and spring climate change timing and nature, as spring conditions are a crucial factor in determining the impact of winter warming on plant performance. This article is protected by copyright. All rights reserved.\n
\n\n\n\n \n\n \n \n \n \n \n \n Inversion frequencies and phenotypic effects are modulated by the environment: insights from a reciprocal transplant study in Coelopa frigida.\n \n \n \n \n\n\n \n Berdan, E.; Rosenquist, H.; Larson, K.; and Wellenreuther, M.\n\n\n \n\n\n\n Evolutionary Ecology, 32(6): 683–698. October 2018.\n \n\n\n\n
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\n\n\n@article{berdan_inversion_2018,\n\ttitle = {Inversion frequencies and phenotypic effects are modulated by the environment: insights from a reciprocal transplant study in {Coelopa} frigida},\n\tvolume = {32},\n\tissn = {1573-8477},\n\tshorttitle = {Inversion frequencies and phenotypic effects are modulated by the environment},\n\turl = {https://doi.org/10.1007/s10682-018-9960-5},\n\tdoi = {10.1007/s10682-018-9960-5},\n\tabstract = {Understanding how environmental variation drives phenotypic diversification within species is a major objective in evolutionary biology. The seaweed fly Coelopa frigida provides an excellent model for the study of genetically driven phenotypes because it carries an α/β inversion polymorphism that affects body size. Coelopa frigida inhabits highly variable beds of decomposing seaweed on the coast in Scandinavia thus providing a suitable test ground to investigate the genetic effects of substrate on both the frequency of the inversion (directional selection) and on the phenotype (genotype × environment effects). Here we use a reciprocal transplant experiment to test the effect of the α/β inversion on body size traits and development time across four suitable natural breeding substrates from the clinal distribution. We show that while development time is unaffected by G × E effects, both the frequency of the inversion and the relative phenotypic effects of the inversion on body size differ between population × substrate combinations. This indicates that the environment modulates the fitness as well as the phenotypic effects of the inversion karyotypes. It further suggests that the inversion may have accumulated qualitatively different mutations in different populations that interact with the environment. Together our results are consistent with the idea that the inversion in C. frigida likely evolves via a combination of local mutation, G × E effects, and differential fitness of inversion karyotypes in heterogeneous environments.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2018-10-25},\n\tjournal = {Evolutionary Ecology},\n\tauthor = {Berdan, Emma and Rosenquist, Hanna and Larson, Keith and Wellenreuther, Maren},\n\tmonth = oct,\n\tyear = {2018},\n\tkeywords = {\\#nosource, Adaptation, Coelopa frigida, Frequency effects, G × E interactions, Inversion polymorphism},\n\tpages = {683--698},\n}\n\n\n\n\n\n Understanding how environmental variation drives phenotypic diversification within species is a major objective in evolutionary biology. The seaweed fly Coelopa frigida provides an excellent model for the study of genetically driven phenotypes because it carries an α/β inversion polymorphism that affects body size. Coelopa frigida inhabits highly variable beds of decomposing seaweed on the coast in Scandinavia thus providing a suitable test ground to investigate the genetic effects of substrate on both the frequency of the inversion (directional selection) and on the phenotype (genotype × environment effects). Here we use a reciprocal transplant experiment to test the effect of the α/β inversion on body size traits and development time across four suitable natural breeding substrates from the clinal distribution. We show that while development time is unaffected by G × E effects, both the frequency of the inversion and the relative phenotypic effects of the inversion on body size differ between population × substrate combinations. This indicates that the environment modulates the fitness as well as the phenotypic effects of the inversion karyotypes. It further suggests that the inversion may have accumulated qualitatively different mutations in different populations that interact with the environment. Together our results are consistent with the idea that the inversion in C. frigida likely evolves via a combination of local mutation, G × E effects, and differential fitness of inversion karyotypes in heterogeneous environments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Using laboratory incubations to predict the fate of pharmaceuticals in aquatic ecosystems.\n \n \n \n \n\n\n \n Fahlman, J.; Fick, J.; Karlsson, J.; Jonsson, M.; Brodin, T.; and Klaminder, J.\n\n\n \n\n\n\n Environmental Chemistry, 15(8): 463–471. November 2018.\n \n\n\n\n
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\n\n\n@article{fahlman_using_2018,\n\ttitle = {Using laboratory incubations to predict the fate of pharmaceuticals in aquatic ecosystems},\n\tvolume = {15},\n\tissn = {1449-8979},\n\turl = {http://www.publish.csiro.au/EN/EN18154},\n\tdoi = {10.1071/EN18154},\n\tabstract = {Environmental context Environmental persistence of excreted pharmaceuticals in aquatic ecosystems is usually predicted using small-scale laboratory experiments assumed to simulate natural conditions. We studied five pharmaceuticals comparing their removal rates from water under laboratory conditions and under natural environmental conditions existing in a large pond. We found that the laboratory conditions did not fully capture the complexity within the pond, which led to different removal rates in the two systems. Abstract Environmental persistence is a key property when evaluating risks with excreted pharmaceuticals in aquatic ecosystems. Such persistence is typically predicted using small-scale laboratory incubations, but the variation in aquatic environments and scarcity of field studies to verify laboratory-based persistence estimates create uncertainties around the predictive power of these incubations. In this study we: (1) assess the persistence of five pharmaceuticals (diclofenac, diphenhydramine, hydroxyzine, trimethoprim and oxazepam) in laboratory experiments under different environmental conditions; and (2) use a three-month-long field study in an aquatic ecosystem to verify the laboratory-based persistence estimates. In our laboratory assays, we found that water temperature (TEMP), concentrations of organic solutes (TOC), presence of sediment (SED), and solar radiation (SOL) individually affected dissipation rates. Moreover, we identified rarely studied interaction effects between the treatments (i.e. SOL × SED and TEMP × SOL), which affected the persistence of the studied drugs. Half-lives obtained from the laboratory assays largely explained the dissipation rates during the first week of the field study. However, none of the applied models could accurately predict the long-term dissipation rates (month time-scale) from the water column. For example, the studied antibioticum (trimethoprim) and the anti-anxiety drug (oxazepam) remained at detectable levels in the aquatic environment long after ({\\textasciitilde}150 days) our laboratory based models predicted complete dissipation. We conclude that small-scale laboratory incubations seem sufficient to approximate the short-term (i.e. within a week) dissipation rate of drugs in aquatic ecosystems. However, this simplistic approach does not capture interacting environmental processes that preserve a fraction of the dissolved pharmaceuticals for months in natural water bodies.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2019-02-21},\n\tjournal = {Environmental Chemistry},\n\tauthor = {Fahlman, Johan and Fick, Jerker and Karlsson, Jan and Jonsson, Micael and Brodin, Tomas and Klaminder, Jonatan},\n\tmonth = nov,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {463--471},\n}\n\n\n\n\n\n Environmental context Environmental persistence of excreted pharmaceuticals in aquatic ecosystems is usually predicted using small-scale laboratory experiments assumed to simulate natural conditions. We studied five pharmaceuticals comparing their removal rates from water under laboratory conditions and under natural environmental conditions existing in a large pond. We found that the laboratory conditions did not fully capture the complexity within the pond, which led to different removal rates in the two systems. Abstract Environmental persistence is a key property when evaluating risks with excreted pharmaceuticals in aquatic ecosystems. Such persistence is typically predicted using small-scale laboratory incubations, but the variation in aquatic environments and scarcity of field studies to verify laboratory-based persistence estimates create uncertainties around the predictive power of these incubations. In this study we: (1) assess the persistence of five pharmaceuticals (diclofenac, diphenhydramine, hydroxyzine, trimethoprim and oxazepam) in laboratory experiments under different environmental conditions; and (2) use a three-month-long field study in an aquatic ecosystem to verify the laboratory-based persistence estimates. In our laboratory assays, we found that water temperature (TEMP), concentrations of organic solutes (TOC), presence of sediment (SED), and solar radiation (SOL) individually affected dissipation rates. Moreover, we identified rarely studied interaction effects between the treatments (i.e. SOL × SED and TEMP × SOL), which affected the persistence of the studied drugs. Half-lives obtained from the laboratory assays largely explained the dissipation rates during the first week of the field study. However, none of the applied models could accurately predict the long-term dissipation rates (month time-scale) from the water column. For example, the studied antibioticum (trimethoprim) and the anti-anxiety drug (oxazepam) remained at detectable levels in the aquatic environment long after (~150 days) our laboratory based models predicted complete dissipation. We conclude that small-scale laboratory incubations seem sufficient to approximate the short-term (i.e. within a week) dissipation rate of drugs in aquatic ecosystems. However, this simplistic approach does not capture interacting environmental processes that preserve a fraction of the dissolved pharmaceuticals for months in natural water bodies.\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-Term Climate Regime Modulates the Impact of Short-Term Climate Variability on Decomposition in Alpine Grassland Soils.\n \n \n \n \n\n\n \n Althuizen, I. H. J.; Lee, H.; Sarneel, J. M.; and Vandvik, V.\n\n\n \n\n\n\n Ecosystems, 21(8): 1580–1592. December 2018.\n \n\n\n\n
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\n\n\n@article{althuizen_long-term_2018,\n\ttitle = {Long-{Term} {Climate} {Regime} {Modulates} the {Impact} of {Short}-{Term} {Climate} {Variability} on {Decomposition} in {Alpine} {Grassland} {Soils}},\n\tvolume = {21},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-018-0241-5},\n\tdoi = {10.1007/s10021-018-0241-5},\n\tabstract = {Decomposition of plant litter is an important process in the terrestrial carbon cycle and makes up approximately 70\\% of the global carbon flux from soils to the atmosphere. Climate change is expected to have significant direct and indirect effects on the litter decomposition processes at various timescales. Using the TeaBag Index, we investigated the impact on decomposition of short-term direct effects of temperature and precipitation by comparing temporal variability over years, versus long-term climate impacts that incorporate indirect effects mediated through environmental changes by comparing sites along climatic gradients. We measured the initial decomposition rate (k) and the stabilization factor (S; amount of labile litter stabilizing) across a climate grid combining three levels of summer temperature (6.5–10.5°C) with four levels of annual precipitation (600–2700 mm) in three summers with varying temperature and precipitation. Several (a)biotic factors were measured to characterize environmental differences between sites. Increased temperatures enhanced k, whereas increased precipitation decreased k across years and climatic regimes. In contrast, S showed diverse responses to annual changes in temperature and precipitation between climate regimes. Stabilization of labile litter fractions increased with temperature only in boreal and sub-alpine sites, while it decreased with increasing precipitation only in sub-alpine and alpine sites. Environmental factors such as soil pH, soil C/N, litter C/N, and plant diversity that are associated with long-term climate variation modulate the response of k and S. This highlights the importance of long-term climate in shaping the environmental conditions that influences the response of decomposition processes to climate change.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2019-04-05},\n\tjournal = {Ecosystems},\n\tauthor = {Althuizen, Inge H. J. and Lee, Hanna and Sarneel, Judith M. and Vandvik, Vigdis},\n\tmonth = dec,\n\tyear = {2018},\n\tkeywords = {\\#nosource, annual variability, climate change, decomposition, grassland, litter bag, precipitation, tea bag index, temperature},\n\tpages = {1580--1592},\n}\n\n\n\n\n\n Decomposition of plant litter is an important process in the terrestrial carbon cycle and makes up approximately 70% of the global carbon flux from soils to the atmosphere. Climate change is expected to have significant direct and indirect effects on the litter decomposition processes at various timescales. Using the TeaBag Index, we investigated the impact on decomposition of short-term direct effects of temperature and precipitation by comparing temporal variability over years, versus long-term climate impacts that incorporate indirect effects mediated through environmental changes by comparing sites along climatic gradients. We measured the initial decomposition rate (k) and the stabilization factor (S; amount of labile litter stabilizing) across a climate grid combining three levels of summer temperature (6.5–10.5°C) with four levels of annual precipitation (600–2700 mm) in three summers with varying temperature and precipitation. Several (a)biotic factors were measured to characterize environmental differences between sites. Increased temperatures enhanced k, whereas increased precipitation decreased k across years and climatic regimes. In contrast, S showed diverse responses to annual changes in temperature and precipitation between climate regimes. Stabilization of labile litter fractions increased with temperature only in boreal and sub-alpine sites, while it decreased with increasing precipitation only in sub-alpine and alpine sites. Environmental factors such as soil pH, soil C/N, litter C/N, and plant diversity that are associated with long-term climate variation modulate the response of k and S. This highlights the importance of long-term climate in shaping the environmental conditions that influences the response of decomposition processes to climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Ecological Restoration as a Means of Managing Inland Flood Hazards.\n \n \n \n \n\n\n \n Nilsson, C.; Riis, T.; Sarneel, J. M.; and Svavarsdóttir, K.\n\n\n \n\n\n\n BioScience, 68(2): 89–99. February 2018.\n \n\n\n\n
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\n\n\n@article{nilsson_ecological_2018,\n\ttitle = {Ecological {Restoration} as a {Means} of {Managing} {Inland} {Flood} {Hazards}},\n\tvolume = {68},\n\tissn = {0006-3568},\n\turl = {https://academic.oup.com/bioscience/article/68/2/89/4797263},\n\tdoi = {10.1093/biosci/bix148},\n\tabstract = {Abstract. Many streams and rivers experience major floods. Historically, human societies have responded to such floods by moving away from them or by abating t},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2019-03-27},\n\tjournal = {BioScience},\n\tauthor = {Nilsson, Christer and Riis, Tenna and Sarneel, Judith M. and Svavarsdóttir, Kristín},\n\tmonth = feb,\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {89--99},\n}\n\n\n\n\n\n Abstract. Many streams and rivers experience major floods. Historically, human societies have responded to such floods by moving away from them or by abating t\n
\n\n\n\n \n\n \n \n \n \n \n \n Ecosystem engineers in rivers: An introduction to how and where organisms create positive biogeomorphic feedbacks.\n \n \n \n \n\n\n \n Polvi, L. E.; and Sarneel, J. M.\n\n\n \n\n\n\n Wiley Interdisciplinary Reviews: Water, 5(2): e1271. 2018.\n \n\n\n\n
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\n\n\n@article{polvi_ecosystem_2018,\n\ttitle = {Ecosystem engineers in rivers: {An} introduction to how and where organisms create positive biogeomorphic feedbacks},\n\tvolume = {5},\n\tcopyright = {© 2017 Wiley Periodicals, Inc.},\n\tissn = {2049-1948},\n\tshorttitle = {Ecosystem engineers in rivers},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/wat2.1271},\n\tdoi = {10.1002/wat2.1271},\n\tabstract = {Ecosystem engineers substantially alter physical flow characteristics and shape a river's form and function. Because the recurrence interval of geomorphic processes and disturbances in rivers commonly match the temporal scale of plants’ life cycles or alterations by animals, the resulting feedbacks are an important component of rivers. In this review, we focus on biota that directly or indirectly induce a physical change in rivers and cause positive feedbacks on the functioning of that organism. We provide an overview of how various ecosystem engineers affect rivers at different temporal and spatial scales and plot them on a conceptual gradient of river types. Various plants engineer the river environment through stabilizing sediment and reducing flow velocities, including macrophytes, woody plants, and algal mats and biofilms. Among animals that engineer, beaver that build dams cause substantial changes to river dynamics. In addition, benthic macroinvertebrates and mussels can stabilize sediment and reduce velocities, and aquatic and riparian grazers modulate the effect of plants. Humans are also considered river ecosystem engineers. Most of the ecosystem engineers reported in literature occur in rivers with low to intermediate relative stability, intermediate channel widths, and small to intermediate grain sizes. Ecosystem engineers that create positive biogeomorphic feedbacks are important to take into account when managing river systems, as many common invasive species are successful due to their engineering capabilities. River restoration can use ecosystem engineers to spur holistic recovery. Future research points towards examining ecosystem engineers on longer spatial and temporal scales and understanding the co-evolution of organisms and landforms through engineering. WIREs Water 2018, 5:e1271. doi: 10.1002/wat2.1271 This article is categorized under: Water and Life {\\textgreater} Nature of Freshwater Ecosystems Water and Life {\\textgreater} Conservation, Management, and Awareness},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2019-03-27},\n\tjournal = {Wiley Interdisciplinary Reviews: Water},\n\tauthor = {Polvi, Lina E. and Sarneel, Judith M.},\n\tyear = {2018},\n\tkeywords = {\\#nosource},\n\tpages = {e1271},\n}\n\n\n\n\n\n Ecosystem engineers substantially alter physical flow characteristics and shape a river's form and function. Because the recurrence interval of geomorphic processes and disturbances in rivers commonly match the temporal scale of plants’ life cycles or alterations by animals, the resulting feedbacks are an important component of rivers. In this review, we focus on biota that directly or indirectly induce a physical change in rivers and cause positive feedbacks on the functioning of that organism. We provide an overview of how various ecosystem engineers affect rivers at different temporal and spatial scales and plot them on a conceptual gradient of river types. Various plants engineer the river environment through stabilizing sediment and reducing flow velocities, including macrophytes, woody plants, and algal mats and biofilms. Among animals that engineer, beaver that build dams cause substantial changes to river dynamics. In addition, benthic macroinvertebrates and mussels can stabilize sediment and reduce velocities, and aquatic and riparian grazers modulate the effect of plants. Humans are also considered river ecosystem engineers. Most of the ecosystem engineers reported in literature occur in rivers with low to intermediate relative stability, intermediate channel widths, and small to intermediate grain sizes. Ecosystem engineers that create positive biogeomorphic feedbacks are important to take into account when managing river systems, as many common invasive species are successful due to their engineering capabilities. River restoration can use ecosystem engineers to spur holistic recovery. Future research points towards examining ecosystem engineers on longer spatial and temporal scales and understanding the co-evolution of organisms and landforms through engineering. WIREs Water 2018, 5:e1271. doi: 10.1002/wat2.1271 This article is categorized under: Water and Life \\textgreater Nature of Freshwater Ecosystems Water and Life \\textgreater Conservation, Management, and Awareness\n
\n\n\n\n \n\n \n \n \n \n \n \n Quality transformation of dissolved organic carbon during water transit through lakes: contrasting controls by photochemical and biological processes.\n \n \n \n \n\n\n \n Berggren, M.; Klaus, M.; Selvam, B. P.; Ström, L.; Laudon, H.; Jansson, M.; and Karlsson, J.\n\n\n \n\n\n\n Biogeosciences, 15(2): 457–470. January 2018.\n 00000\n\n\n\n
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\n\n\n@article{berggren_quality_2018,\n\ttitle = {Quality transformation of dissolved organic carbon during water transit through lakes: contrasting controls by photochemical and biological processes},\n\tvolume = {15},\n\tissn = {1726-4189},\n\tshorttitle = {Quality transformation of dissolved organic carbon during water transit through lakes},\n\turl = {https://www.biogeosciences.net/15/457/2018/},\n\tdoi = {10.5194/bg-15-457-2018},\n\tabstract = {Dissolved organic carbon (DOC) may be removed, transformed, or added during water transit through lakes, resulting in changes in DOC composition and pigmentation (color). However, the process-based understanding of these changes is incomplete, especially for headwater lakes. We hypothesized that because heterotrophic bacteria preferentially consume noncolored DOC, while photochemical processing removes colored fractions, the overall changes in DOC color upon water passage through a lake depend on the relative importance of these two processes, accordingly. To test this hypothesis we combined laboratory experiments with field studies in nine boreal lakes, assessing both the relative importance of different DOC decay processes (biological or photochemical) and the loss of color during water transit time (WTT) through the lakes. We found that influence from photo-decay dominated changes in DOC quality in the epilimnia of relatively clear headwater lakes, resulting in systematic and selective net losses of colored DOC. However, in highly pigmented brown-water lakes (absorbance at 420 nm {\\textgreater} 7 m−1) biological processes dominated, and there was no systematic relationship between color loss and WTT. Moreover, in situ data and dark experiments supported our hypothesis on the selective microbial removal of nonpigmented DOC, mainly of low molecular weight, leading to persistent water color in these highly colored lakes. Our study shows that brown headwater lakes may not conform to the commonly reported pattern of the selective removal of colored constituents in freshwaters, as DOC can show a sustained degree of pigmentation upon transit through these lakes.},\n\tnumber = {2},\n\turldate = {2018-02-13},\n\tjournal = {Biogeosciences},\n\tauthor = {Berggren, M. and Klaus, M. and Selvam, B. P. and Ström, L. and Laudon, H. and Jansson, M. and Karlsson, J.},\n\tmonth = jan,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {457--470},\n}\n\n\n\n\n\n Dissolved organic carbon (DOC) may be removed, transformed, or added during water transit through lakes, resulting in changes in DOC composition and pigmentation (color). However, the process-based understanding of these changes is incomplete, especially for headwater lakes. We hypothesized that because heterotrophic bacteria preferentially consume noncolored DOC, while photochemical processing removes colored fractions, the overall changes in DOC color upon water passage through a lake depend on the relative importance of these two processes, accordingly. To test this hypothesis we combined laboratory experiments with field studies in nine boreal lakes, assessing both the relative importance of different DOC decay processes (biological or photochemical) and the loss of color during water transit time (WTT) through the lakes. We found that influence from photo-decay dominated changes in DOC quality in the epilimnia of relatively clear headwater lakes, resulting in systematic and selective net losses of colored DOC. However, in highly pigmented brown-water lakes (absorbance at 420 nm \\textgreater 7 m−1) biological processes dominated, and there was no systematic relationship between color loss and WTT. Moreover, in situ data and dark experiments supported our hypothesis on the selective microbial removal of nonpigmented DOC, mainly of low molecular weight, leading to persistent water color in these highly colored lakes. Our study shows that brown headwater lakes may not conform to the commonly reported pattern of the selective removal of colored constituents in freshwaters, as DOC can show a sustained degree of pigmentation upon transit through these lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Functional Group, Biomass, and Climate Change Effects on Ecological Drought in Semiarid Grasslands.\n \n \n \n \n\n\n \n Wilson, S. D.; Schlaepfer, D. R.; Bradford, J. B.; Lauenroth, W. K.; Duniway, M. C.; Hall, S. A.; Jamiyansharav, K.; Jia, G.; Lkhagva, A.; Munson, S. M.; Pyke, D. A.; and Tietjen, B.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 123(3): 1072–1085. March 2018.\n 00000\n\n\n\n
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\n\n\n@article{wilson_functional_2018,\n\ttitle = {Functional {Group}, {Biomass}, and {Climate} {Change} {Effects} on {Ecological} {Drought} in {Semiarid} {Grasslands}},\n\tvolume = {123},\n\tcopyright = {©2018. American Geophysical Union. All Rights Reserved.},\n\tissn = {2169-8961},\n\turl = {http://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JG004173},\n\tdoi = {10.1002/2017JG004173},\n\tabstract = {Water relations in plant communities are influenced both by contrasting functional groups (grasses and shrubs) and by climate change via complex effects on interception, uptake, and transpiration. We modeled the effects of functional group replacement and biomass increase, both of which can be outcomes of invasion and vegetation management, and climate change on ecological drought (soil water potential below which photosynthesis stops) in 340 semiarid grassland sites over 30 year periods. Relative to control vegetation (climate and site-determined mixes of functional groups), the frequency and duration of drought were increased by shrubs and decreased by annual grasses. The rankings of shrubs, control vegetation, and annual grasses in terms of drought effects were generally consistent in current and future climates, suggesting that current differences among functional groups on drought effects predict future differences. Climate change accompanied by experimentally increased biomass (i.e., the effects of invasions that increase community biomass or management that increases productivity through fertilization or respite from grazing) increased drought frequency and duration and advanced drought onset. Our results suggest that the replacement of perennial temperate semiarid grasslands by shrubs, or increased biomass, can increase ecological drought in both current and future climates.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-07-05},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Wilson, S. D. and Schlaepfer, D. R. and Bradford, J. B. and Lauenroth, W. K. and Duniway, M. C. and Hall, S. A. and Jamiyansharav, K. and Jia, G. and Lkhagva, A. and Munson, S. M. and Pyke, D. A. and Tietjen, B.},\n\tmonth = mar,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, biological invasion, ecosystem function, global change, precipitation},\n\tpages = {1072--1085},\n}\n\n\n\n\n\n Water relations in plant communities are influenced both by contrasting functional groups (grasses and shrubs) and by climate change via complex effects on interception, uptake, and transpiration. We modeled the effects of functional group replacement and biomass increase, both of which can be outcomes of invasion and vegetation management, and climate change on ecological drought (soil water potential below which photosynthesis stops) in 340 semiarid grassland sites over 30 year periods. Relative to control vegetation (climate and site-determined mixes of functional groups), the frequency and duration of drought were increased by shrubs and decreased by annual grasses. The rankings of shrubs, control vegetation, and annual grasses in terms of drought effects were generally consistent in current and future climates, suggesting that current differences among functional groups on drought effects predict future differences. Climate change accompanied by experimentally increased biomass (i.e., the effects of invasions that increase community biomass or management that increases productivity through fertilization or respite from grazing) increased drought frequency and duration and advanced drought onset. Our results suggest that the replacement of perennial temperate semiarid grasslands by shrubs, or increased biomass, can increase ecological drought in both current and future climates.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes.\n \n \n \n \n\n\n \n Creed, I. F.; Bergström, A.; Trick, C. G.; Grimm, N. B.; Hessen, D. O.; Karlsson, J.; Kidd, K. A.; Kritzberg, E.; McKnight, D. M.; Freeman, E. C.; Senar, O. E.; Andersson, A.; Ask, J.; Berggren, M.; Cherif, M.; Giesler, R.; Hotchkiss, E. R.; Kortelainen, P.; Palta, M. M.; Vrede, T.; and Weyhenmeyer, G. A.\n\n\n \n\n\n\n Global Change Biology, 24(8): 3692–3714. March 2018.\n 00001\n\n\n\n
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\n\n\n@article{creed_global_2018,\n\ttitle = {Global change-driven effects on dissolved organic matter composition: {Implications} for food webs of northern lakes},\n\tvolume = {24},\n\tcopyright = {© 2018 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\tshorttitle = {Global change-driven effects on dissolved organic matter composition},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14129},\n\tdoi = {10.1111/gcb.14129},\n\tabstract = {Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2018-07-05},\n\tjournal = {Global Change Biology},\n\tauthor = {Creed, Irena F. and Bergström, Ann-Kristin and Trick, Charles G. and Grimm, Nancy B. and Hessen, Dag O. and Karlsson, Jan and Kidd, Karen A. and Kritzberg, Emma and McKnight, Diane M. and Freeman, Erika C. and Senar, Oscar E. and Andersson, Agneta and Ask, Jenny and Berggren, Martin and Cherif, Mehdi and Giesler, Reiner and Hotchkiss, Erin R. and Kortelainen, Pirkko and Palta, Monica M. and Vrede, Tobias and Weyhenmeyer, Gesa A.},\n\tmonth = mar,\n\tyear = {2018},\n\tnote = {00001},\n\tkeywords = {\\#nosource, atmospheric change, cyanobacteria, dissolved organic matter, food webs, lake, mercury, northern},\n\tpages = {3692--3714},\n}\n\n\n\n\n\n Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.\n
\n\n\n\n \n\n \n \n \n \n \n \n A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters.\n \n \n \n \n\n\n \n Engel, F.; Farrell, K. J.; McCullough, I. M.; Scordo, F.; Denfeld, B. A.; Dugan, H. A.; Eyto, E. d.; Hanson, P. C.; McClure, R. P.; Nõges, P.; Nõges, T.; Ryder, E.; Weathers, K. C.; and Weyhenmeyer, G. A.\n\n\n \n\n\n\n The Science of Nature, 105(3-4): 25. April 2018.\n 00000\n\n\n\n
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\n\n\n@article{engel_lake_2018,\n\ttitle = {A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters},\n\tvolume = {105},\n\tissn = {0028-1042, 1432-1904},\n\turl = {https://link.springer.com/article/10.1007/s00114-018-1547-z},\n\tdoi = {10.1007/s00114-018-1547-z},\n\tabstract = {The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO2) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO2 production by mineralization as well as CO2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of 0.70+0.27−0.310.70−0.31+0.27 \\{0.70\\}\\_\\{-0.31\\}{\\textasciicircum}\\{+0.27\\} to 1.52+1.09−0.901.52−0.90+1.09 \\{1.52\\}\\_\\{-0.90\\}{\\textasciicircum}\\{+1.09\\} Pg C yr−1 depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.},\n\tlanguage = {en},\n\tnumber = {3-4},\n\turldate = {2018-07-05},\n\tjournal = {The Science of Nature},\n\tauthor = {Engel, Fabian and Farrell, Kaitlin J. and McCullough, Ian M. and Scordo, Facundo and Denfeld, Blaize A. and Dugan, Hilary A. and Eyto, Elvira de and Hanson, Paul C. and McClure, Ryan P. and Nõges, Peeter and Nõges, Tiina and Ryder, Elizabeth and Weathers, Kathleen C. and Weyhenmeyer, Gesa A.},\n\tmonth = apr,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {25},\n}\n\n\n\n\n\n The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO2) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO2 production by mineralization as well as CO2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of 0.70+0.27−0.310.70−0.31+0.27 \\0.70\\_\\-0.31\\\\textasciicircum\\+0.27\\ to 1.52+1.09−0.901.52−0.90+1.09 \\1.52\\_\\-0.90\\\\textasciicircum\\+1.09\\ Pg C yr−1 depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting plankton stoichiometry and nutrient regeneration in northern arctic and boreal lakes.\n \n \n \n \n\n\n \n Bergström, A.; Karlsson, J.; Karlsson, D.; and Vrede, T.\n\n\n \n\n\n\n Aquatic Sciences, 80(2): 24. April 2018.\n 00000\n\n\n\n
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\n\n\n@article{bergstrom_contrasting_2018,\n\ttitle = {Contrasting plankton stoichiometry and nutrient regeneration in northern arctic and boreal lakes},\n\tvolume = {80},\n\tissn = {1015-1621, 1420-9055},\n\turl = {https://link.springer.com/article/10.1007/s00027-018-0575-2},\n\tdoi = {10.1007/s00027-018-0575-2},\n\tabstract = {Contrasting carbon: nitrogen: phosphorus (C: N: P) stoichiometry between phytoplankton and zooplankton affect consumer growth and phytoplankton nutrient limitation via nutrient recycling by zooplankton. However, no study has assessed how regional differences in terrestrial loadings of organic matter affect plankton N: P stoichiometry and recycling in systems with low N deposition and N-limited phytoplankton. We address this question by using data from 14 unproductive headwater arctic and boreal lakes. We found that boreal lakes had higher lake water- and seston C, N and P concentrations than arctic lakes, whereas seston C: N, C: P and N: P ratios did not differ among regions. Boreal zooplankton were also richer in N and P relative to C, with lower somatic N: P ratios, compared to arctic lakes. Consequently, the estimated N: P imbalances between seston and zooplankton were negative in arctic lakes, indicating zooplankton feeding on phytoplankton of suboptimal N content, resulting in low consumer driven N: P recycling (medians arctic sub-mid and high altitude lakes: 11 and 13). In boreal lakes, estimated N: P imbalance did not differ from zero, with a seston N: P stoichiometry matching the N:P requirements of zooplankton, which resulted in higher consumer driven N: P recycling (median 18). Our results imply that regional climate induced catchment differences, through enhanced terrestrial nutrient inputs, affect plankton stoichiometry by raising consumer N: P recycling ratio and changing zooplankton from being mainly N- (arctic) to NP co-limited (boreal). Browning of lakes, in regions with low N deposition, may therefore promote large-scale regional changes in plankton nutrient limitation with potential feedbacks on pelagic food webs.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2018-07-05},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Bergström, Ann-Kristin and Karlsson, Jan and Karlsson, Daniel and Vrede, Tobias},\n\tmonth = apr,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {24},\n}\n\n\n\n\n\n Contrasting carbon: nitrogen: phosphorus (C: N: P) stoichiometry between phytoplankton and zooplankton affect consumer growth and phytoplankton nutrient limitation via nutrient recycling by zooplankton. However, no study has assessed how regional differences in terrestrial loadings of organic matter affect plankton N: P stoichiometry and recycling in systems with low N deposition and N-limited phytoplankton. We address this question by using data from 14 unproductive headwater arctic and boreal lakes. We found that boreal lakes had higher lake water- and seston C, N and P concentrations than arctic lakes, whereas seston C: N, C: P and N: P ratios did not differ among regions. Boreal zooplankton were also richer in N and P relative to C, with lower somatic N: P ratios, compared to arctic lakes. Consequently, the estimated N: P imbalances between seston and zooplankton were negative in arctic lakes, indicating zooplankton feeding on phytoplankton of suboptimal N content, resulting in low consumer driven N: P recycling (medians arctic sub-mid and high altitude lakes: 11 and 13). In boreal lakes, estimated N: P imbalance did not differ from zero, with a seston N: P stoichiometry matching the N:P requirements of zooplankton, which resulted in higher consumer driven N: P recycling (median 18). Our results imply that regional climate induced catchment differences, through enhanced terrestrial nutrient inputs, affect plankton stoichiometry by raising consumer N: P recycling ratio and changing zooplankton from being mainly N- (arctic) to NP co-limited (boreal). Browning of lakes, in regions with low N deposition, may therefore promote large-scale regional changes in plankton nutrient limitation with potential feedbacks on pelagic food webs.\n
\n\n\n\n \n\n \n \n \n \n \n \n Inverse relationship of epilithic algae and pelagic phosphorus in unproductive lakes: Roles of N2 fixers and light.\n \n \n \n \n\n\n \n Diehl, S.; Thomsson, G.; Kahlert, M.; Guo, J.; Karlsson, J.; and Liess, A.\n\n\n \n\n\n\n Freshwater Biology, 63(7): 662–675. 2018.\n 00000\n\n\n\n
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\n\n\n@article{diehl_inverse_2018,\n\ttitle = {Inverse relationship of epilithic algae and pelagic phosphorus in unproductive lakes: {Roles} of {N2} fixers and light},\n\tvolume = {63},\n\tcopyright = {© 2018 John Wiley \\& Sons Ltd},\n\tissn = {1365-2427},\n\tshorttitle = {Inverse relationship of epilithic algae and pelagic phosphorus in unproductive lakes},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.13103},\n\tdoi = {10.1111/fwb.13103},\n\tabstract = {Phosphorus (P) often limits the biomass of primary producers in freshwater lakes. However, in unproductive northern lakes, where anthropogenic nitrogen (N) deposition is low, N instead of P can limit primary producers. In addition, light can be limiting to primary producers at high concentrations of coloured dissolved organic matter (cDOM), as cDOM is the major determinant of light penetration in these lakes. To address resource limitation of epilithic algal biomass, we repeatedly sampled epilithon (periphyton on stony substrata) in 20 lakes covering a large, correlated cDOM and N-deposition gradient across boreal and subarctic Sweden. Across these lakes, pelagic total N (TN) and total P (TP) were positively correlated, and benthic light supply was negatively correlated, with cDOM. Microscopically determined algal biovolume and epilithic carbon (C), N and P were subsequently regressed against benthic light supply and pelagic TN and TP. Patterns in epilithic biovolume were driven by N2-fixing cyanobacteria, which accounted for 2\\%–90\\% of total epilithic biovolume. Averaged over the growing season, epilithic algal biovolume, C and N were negatively related to TP and positively to TN, and were highest in the clearest, most phosphorus-poor lakes, where epilithon was heavily dominated by potentially N2-fixing cyanobacteria. A structural equation model supports the hypothesis that cDOM had two counteracting effects on total epilithic algal biovolume: a positive one by providing N to algae that depend on dissolved N for growth, and a negative one by shading N2-fixing cyanobacteria, with the negative effect being somewhat stronger. Together, these findings suggest that (1) light and N are the main resources limiting epilithic algal biomass in boreal to subarctic Swedish lakes, (2) epilithic cyanobacteria are more competitive in high-light and low-nitrogen environments, where their N2-fixing ability allows them to reach high biomass, and (3) epilithic N increases with N2 fixer biomass and is—seemingly paradoxically—highest in the most oligotrophic lakes.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2018-07-05},\n\tjournal = {Freshwater Biology},\n\tauthor = {Diehl, Sebastian and Thomsson, Gustaf and Kahlert, Maria and Guo, Junwen and Karlsson, Jan and Liess, Antonia},\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource, dissolved organic matter, light, nitrogen-fixing cyanobacteria, nutrients, periphyton},\n\tpages = {662--675},\n}\n\n\n\n\n\n Phosphorus (P) often limits the biomass of primary producers in freshwater lakes. However, in unproductive northern lakes, where anthropogenic nitrogen (N) deposition is low, N instead of P can limit primary producers. In addition, light can be limiting to primary producers at high concentrations of coloured dissolved organic matter (cDOM), as cDOM is the major determinant of light penetration in these lakes. To address resource limitation of epilithic algal biomass, we repeatedly sampled epilithon (periphyton on stony substrata) in 20 lakes covering a large, correlated cDOM and N-deposition gradient across boreal and subarctic Sweden. Across these lakes, pelagic total N (TN) and total P (TP) were positively correlated, and benthic light supply was negatively correlated, with cDOM. Microscopically determined algal biovolume and epilithic carbon (C), N and P were subsequently regressed against benthic light supply and pelagic TN and TP. Patterns in epilithic biovolume were driven by N2-fixing cyanobacteria, which accounted for 2%–90% of total epilithic biovolume. Averaged over the growing season, epilithic algal biovolume, C and N were negatively related to TP and positively to TN, and were highest in the clearest, most phosphorus-poor lakes, where epilithon was heavily dominated by potentially N2-fixing cyanobacteria. A structural equation model supports the hypothesis that cDOM had two counteracting effects on total epilithic algal biovolume: a positive one by providing N to algae that depend on dissolved N for growth, and a negative one by shading N2-fixing cyanobacteria, with the negative effect being somewhat stronger. Together, these findings suggest that (1) light and N are the main resources limiting epilithic algal biomass in boreal to subarctic Swedish lakes, (2) epilithic cyanobacteria are more competitive in high-light and low-nitrogen environments, where their N2-fixing ability allows them to reach high biomass, and (3) epilithic N increases with N2 fixer biomass and is—seemingly paradoxically—highest in the most oligotrophic lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Emissions from thaw ponds largely offset the carbon sink of northern permafrost wetlands.\n \n \n \n \n\n\n \n Kuhn, M.; Lundin, E. J.; Giesler, R.; Johansson, M.; and Karlsson, J.\n\n\n \n\n\n\n Scientific Reports, 8(1): 9535. June 2018.\n 00000\n\n\n\n
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\n\n\n@article{kuhn_emissions_2018,\n\ttitle = {Emissions from thaw ponds largely offset the carbon sink of northern permafrost wetlands},\n\tvolume = {8},\n\tcopyright = {2018 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-018-27770-x},\n\tdoi = {10.1038/s41598-018-27770-x},\n\tabstract = {Northern regions have received considerable attention not only because the effects of climate change are amplified at high latitudes but also because this region holds vast amounts of carbon (C) stored in permafrost. These carbon stocks are vulnerable to warming temperatures and increased permafrost thaw and the breakdown and release of soil C in the form of carbon dioxide (CO2) and methane (CH4). The majority of research has focused on quantifying and upscaling the effects of thaw on CO2 and CH4 emissions from terrestrial systems. However, small ponds formed in permafrost wetlands following thawing have been recognized as hotspots for C emissions. Here, we examined the importance of small ponds for C fluxes in two permafrost wetland ecosystems in northern Sweden. Detailed flux estimates of thaw ponds during the growing season show that ponds emit, on average (±SD), 279 ± 415 and 7 ± 11 mmol C m���2 d−1 of CO2 and CH4, respectively. Importantly, addition of pond emissions to the total C budget of the wetland decreases the C sink by {\\textasciitilde}39\\%. Our results emphasize the need for integrated research linking C cycling on land and in water in order to make correct assessments of contemporary C balances.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-07-04},\n\tjournal = {Scientific Reports},\n\tauthor = {Kuhn, McKenzie and Lundin, Erik J. and Giesler, Reiner and Johansson, Margareta and Karlsson, Jan},\n\tmonth = jun,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {9535},\n}\n\n\n\n\n\n Northern regions have received considerable attention not only because the effects of climate change are amplified at high latitudes but also because this region holds vast amounts of carbon (C) stored in permafrost. These carbon stocks are vulnerable to warming temperatures and increased permafrost thaw and the breakdown and release of soil C in the form of carbon dioxide (CO2) and methane (CH4). The majority of research has focused on quantifying and upscaling the effects of thaw on CO2 and CH4 emissions from terrestrial systems. However, small ponds formed in permafrost wetlands following thawing have been recognized as hotspots for C emissions. Here, we examined the importance of small ponds for C fluxes in two permafrost wetland ecosystems in northern Sweden. Detailed flux estimates of thaw ponds during the growing season show that ponds emit, on average (±SD), 279 ± 415 and 7 ± 11 mmol C m���2 d−1 of CO2 and CH4, respectively. Importantly, addition of pond emissions to the total C budget of the wetland decreases the C sink by ~39%. Our results emphasize the need for integrated research linking C cycling on land and in water in order to make correct assessments of contemporary C balances.\n
\n\n\n\n \n\n \n \n \n \n \n \n Context-dependent interactions and the regulation of species richness in freshwater fish.\n \n \n \n \n\n\n \n MacDougall, A. S.; Harvey, E.; McCune, J. L.; Nilsson, K. A.; Bennett, J.; Firn, J.; Bartley, T.; Grace, J. B.; Kelly, J.; Tunney, T. D.; McMeans, B.; Matsuzaki, S. S.; Kadoya, T.; Esch, E.; Cazelles, K.; Lester, N.; and McCann, K. S.\n\n\n \n\n\n\n Nature Communications, 9(1): 973. March 2018.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{macdougall_context-dependent_2018,\n\ttitle = {Context-dependent interactions and the regulation of species richness in freshwater fish},\n\tvolume = {9},\n\tcopyright = {2018 The Author(s)},\n\tissn = {2041-1723},\n\turl = {https://www.nature.com/articles/s41467-018-03419-1},\n\tdoi = {10.1038/s41467-018-03419-1},\n\tabstract = {Species richness patterns are driven by biotic and abiotic factors, the relative strengths of which are unclear. Here, the authors test how species interactions or environmental traits influence fish richness across over 700 Canadian lakes, showing a surprisingly small role of negative interactions.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-03-10},\n\tjournal = {Nature Communications},\n\tauthor = {MacDougall, Andrew S. and Harvey, Eric and McCune, Jenny L. and Nilsson, Karin A. and Bennett, Joseph and Firn, Jennifer and Bartley, Timothy and Grace, James B. and Kelly, Jocelyn and Tunney, Tyler D. and McMeans, Bailey and Matsuzaki, Shin-Ichiro S. and Kadoya, Taku and Esch, Ellen and Cazelles, Kevin and Lester, Nigel and McCann, Kevin S.},\n\tmonth = mar,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {973},\n}\n\n\n\n\n\n Species richness patterns are driven by biotic and abiotic factors, the relative strengths of which are unclear. Here, the authors test how species interactions or environmental traits influence fish richness across over 700 Canadian lakes, showing a surprisingly small role of negative interactions.\n
\n\n\n\n \n\n \n \n \n \n \n \n A synthesis of carbon dioxide and methane dynamics during the ice-covered period of northern lakes.\n \n \n \n \n\n\n \n Denfeld, B. A.; Baulch, H. M.; del Giorgio, P. A.; Hampton, S. E.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 3(3): 117–131. June 2018.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{denfeld_synthesis_2018,\n\ttitle = {A synthesis of carbon dioxide and methane dynamics during the ice-covered period of northern lakes},\n\tvolume = {3},\n\tissn = {23782242},\n\tshorttitle = {A synthesis of carbon dioxide and methane dynamics during the ice-covered period of northern lakes},\n\turl = {http://doi.wiley.com/10.1002/lol2.10079},\n\tdoi = {10.1002/lol2.10079},\n\tabstract = {The ice-covered period on lakes in the northern hemisphere has often been neglected or assumed to have less importance relative to the open water season. However, recent studies challenge this convention, suggesting that the winter period is more dynamic than previously thought. In this review, we synthesize the current understanding of under-ice carbon dioxide (CO2) and methane (CH4) dynamics, highlighting the annual importance of CO2 and CH4 emissions from lakes at ice-melt. We compiled data from 25 studies that showed that the ice-melt period represents 17\\% and 27\\% of the annual CO2 and CH4 emissions, respectively. We also found evidence that the magnitude and type of emission (i.e., CO2 and CH4) varies with characteristics of lakes including geographic location, lake morphometry, and physicochemical conditions. The scarcity of winter and spring carbon data from northern lakes represents a major gap in our understanding of annual budgets in these lakes and calls for future research during this key period.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-07-05},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Denfeld, Blaize A. and Baulch, Helen M. and del Giorgio, Paul A. and Hampton, Stephanie E. and Karlsson, Jan},\n\tmonth = jun,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {117--131},\n}\n\n\n\n\n\n The ice-covered period on lakes in the northern hemisphere has often been neglected or assumed to have less importance relative to the open water season. However, recent studies challenge this convention, suggesting that the winter period is more dynamic than previously thought. In this review, we synthesize the current understanding of under-ice carbon dioxide (CO2) and methane (CH4) dynamics, highlighting the annual importance of CO2 and CH4 emissions from lakes at ice-melt. We compiled data from 25 studies that showed that the ice-melt period represents 17% and 27% of the annual CO2 and CH4 emissions, respectively. We also found evidence that the magnitude and type of emission (i.e., CO2 and CH4) varies with characteristics of lakes including geographic location, lake morphometry, and physicochemical conditions. The scarcity of winter and spring carbon data from northern lakes represents a major gap in our understanding of annual budgets in these lakes and calls for future research during this key period.\n
\n\n\n\n \n\n \n \n \n \n \n \n Weak response of greenhouse gas emissions to whole lake N enrichment: Greenhouse gas emissions from lakes.\n \n \n \n \n\n\n \n Klaus, M.; Bergström, A.; Jonsson, A.; Deininger, A.; Geibrink, E.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 63(S1): S340–S353. March 2018.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{klaus_weak_2018,\n\ttitle = {Weak response of greenhouse gas emissions to whole lake {N} enrichment: {Greenhouse} gas emissions from lakes},\n\tvolume = {63},\n\tissn = {00243590},\n\tshorttitle = {Weak response of greenhouse gas emissions to whole lake {N} enrichment},\n\turl = {http://doi.wiley.com/10.1002/lno.10743},\n\tdoi = {10.1002/lno.10743},\n\tabstract = {Global warming and land use scenarios suggest increased 21st century nitrogen (N) inputs to aquatic systems. Nitrogen affects in-lake processing and, potentially, atmospheric exchange of greenhouse gases, probably being most relevant in unproductive systems. Here, we test for the first time the effect of a whole-lake experimental increase (threefold) in external nitrate loads on the atmospheric exchange of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from N-limited unproductive boreal lakes. Nitrate enrichment effects were assessed within a paired Before/After-Control/Impact framework based on 2-hourly to biweekly surface-water sampling of dissolved gas concentrations, and monthly whole-lake inventory surveys, carried out over 4 yrs in six lakes. Nitrate enrichment did not affect gas exchange during summer stratification and whole-lake gas inventories during summer and winter stratification. This finding specifically emphasizes the modest role of internal carbon fixation for the CO2 dynamics of unproductive boreal lakes. A global synthesis of 52 published studies revealed a wide range of nutrient fertilization effects, both in systems similar to our experimental lakes, and other more productive systems. Effects depended mainly on the spatiotemporal scale of the study and became more pronounced when N enrichment was combined with phosphorous. Conclusively, although short-term and habitat-specific effects can occur, changes in N supply have only weak whole-ecosystem effects on greenhouse gas emissions from unproductive boreal lakes.},\n\tlanguage = {en},\n\tnumber = {S1},\n\turldate = {2018-05-21},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Klaus, Marcus and Bergström, Ann-Kristin and Jonsson, Anders and Deininger, Anne and Geibrink, Erik and Karlsson, Jan},\n\tmonth = mar,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {S340--S353},\n}\n\n\n\n\n\n Global warming and land use scenarios suggest increased 21st century nitrogen (N) inputs to aquatic systems. Nitrogen affects in-lake processing and, potentially, atmospheric exchange of greenhouse gases, probably being most relevant in unproductive systems. Here, we test for the first time the effect of a whole-lake experimental increase (threefold) in external nitrate loads on the atmospheric exchange of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from N-limited unproductive boreal lakes. Nitrate enrichment effects were assessed within a paired Before/After-Control/Impact framework based on 2-hourly to biweekly surface-water sampling of dissolved gas concentrations, and monthly whole-lake inventory surveys, carried out over 4 yrs in six lakes. Nitrate enrichment did not affect gas exchange during summer stratification and whole-lake gas inventories during summer and winter stratification. This finding specifically emphasizes the modest role of internal carbon fixation for the CO2 dynamics of unproductive boreal lakes. A global synthesis of 52 published studies revealed a wide range of nutrient fertilization effects, both in systems similar to our experimental lakes, and other more productive systems. Effects depended mainly on the spatiotemporal scale of the study and became more pronounced when N enrichment was combined with phosphorous. Conclusively, although short-term and habitat-specific effects can occur, changes in N supply have only weak whole-ecosystem effects on greenhouse gas emissions from unproductive boreal lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Allochthonous organic matter supports benthic but not pelagic food webs in shallow coastal ecosystems.\n \n \n \n \n\n\n \n Bartels, P.; Ask, J.; Andersson, A.; Karlsson, J.; and Giesler, R.\n\n\n \n\n\n\n Ecosystems, 21: 1459–1470. February 2018.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{bartels_allochthonous_2018,\n\ttitle = {Allochthonous organic matter supports benthic but not pelagic food webs in shallow coastal ecosystems},\n\tvolume = {21},\n\tissn = {1432-9840, 1435-0629},\n\turl = {https://link.springer.com/article/10.1007/s10021-018-0233-5},\n\tdoi = {10.1007/s10021-018-0233-5},\n\tabstract = {Rivers transport large amounts of allochthonous organic matter (OM) to the ocean every year, but there are still fundamental gaps in how allochthonous OM is processed in the marine environment. Here, we estimated the relative contribution of allochthonous OM (allochthony) to the biomass of benthic and pelagic consumers in a shallow coastal ecosystem in the northern Baltic Sea. We used deuterium as a tracer of allochthony and assessed both temporal variation (monthly from May to August) and spatial variation (within and outside river plume). We found variability in allochthony in space and time and across species, with overall higher values for zoobenthos (26.2 ± 20.9\\%) than for zooplankton (0.8 ± 0.3\\%). Zooplankton allochthony was highest in May and very low during the other months, likely as a result of high inputs of allochthonous OM during the spring flood that fueled the pelagic food chain for a short period. In contrast, zoobenthos allochthony was only lower in June and remained high during the other months. Allochthony of zoobenthos was generally higher close to the river mouth than outside of the river plume, whereas it did not vary spatially for zooplankton. Last, zoobenthos allochthony was higher in deeper than in shallower areas, indicating that allochthonous OM might be more important when autochthonous resources are limited. Our results suggest that climate change predictions of increasing inputs of allochthonous OM to coastal ecosystems may affect basal energy sources supporting coastal food webs.},\n\tlanguage = {en},\n\turldate = {2018-03-10},\n\tjournal = {Ecosystems},\n\tauthor = {Bartels, Pia and Ask, Jenny and Andersson, Agneta and Karlsson, Jan and Giesler, Reiner},\n\tmonth = feb,\n\tyear = {2018},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {1459--1470},\n}\n\n\n Rivers transport large amounts of allochthonous organic matter (OM) to the ocean every year, but there are still fundamental gaps in how allochthonous OM is processed in the marine environment. Here, we estimated the relative contribution of allochthonous OM (allochthony) to the biomass of benthic and pelagic consumers in a shallow coastal ecosystem in the northern Baltic Sea. We used deuterium as a tracer of allochthony and assessed both temporal variation (monthly from May to August) and spatial variation (within and outside river plume). We found variability in allochthony in space and time and across species, with overall higher values for zoobenthos (26.2 ± 20.9%) than for zooplankton (0.8 ± 0.3%). Zooplankton allochthony was highest in May and very low during the other months, likely as a result of high inputs of allochthonous OM during the spring flood that fueled the pelagic food chain for a short period. In contrast, zoobenthos allochthony was only lower in June and remained high during the other months. Allochthony of zoobenthos was generally higher close to the river mouth than outside of the river plume, whereas it did not vary spatially for zooplankton. Last, zoobenthos allochthony was higher in deeper than in shallower areas, indicating that allochthonous OM might be more important when autochthonous resources are limited. Our results suggest that climate change predictions of increasing inputs of allochthonous OM to coastal ecosystems may affect basal energy sources supporting coastal food webs.\n
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\n \n \n\n \n \n \n \n \n \n Open tundra persist, but arctic features decline—Vegetation changes in the warming Fennoscandian tundra.\n \n \n \n \n\n\n \n Vuorinen, K. E. M.; Oksanen, L.; Oksanen, T.; Pyykönen, A.; Olofsson, J.; and Virtanen, R.\n\n\n \n\n\n\n Global Change Biology, 23(9): 3794–3807. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13710\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{vuorinen_open_2017,\n\ttitle = {Open tundra persist, but arctic features decline—{Vegetation} changes in the warming {Fennoscandian} tundra},\n\tvolume = {23},\n\tcopyright = {© 2017 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13710},\n\tdoi = {10.1111/gcb.13710},\n\tabstract = {In the forest-tundra ecotone of the North Fennoscandian inland, summer and winter temperatures have increased by two to three centigrades since 1965, which is expected to result in major vegetation changes. To document the expected expansion of woodlands and scrublands and its impact on the arctic vegetation, we repeated a vegetation transect study conducted in 1976 in the Darju, spanning from woodland to a summit, 200 m above the tree line. Contrary to our expectations, tree line movement was not detected, and there was no increase in willows or shrubby mountain birches, either. Nevertheless, the stability of tundra was apparent. Small-sized, poorly competing arctic species had declined, lichen cover had decreased, and vascular plants, especially evergreen ericoid dwarf shrubs, had gained ground. The novel climate seems to favour competitive clonal species and species thriving in closed vegetation, creating a community hostile for seedling establishment, but equally hostile for many arctic species, too. Preventing trees and shrubs from invading the tundra is thus not sufficient for conserving arctic biota in the changing climate. The only dependable cure is to stop the global warming.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Vuorinen, Katariina E. M. and Oksanen, Lauri and Oksanen, Tarja and Pyykönen, Anni and Olofsson, Johan and Virtanen, Risto},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13710},\n\tkeywords = {\\#nosource, Arctic, Empetrum nigrum, Lichens, alpine, arctic, climate change, disturbance, lichens, mosses, reindeer, tree line, tundra, vegetation},\n\tpages = {3794--3807},\n}\n\n\n\n\n\n In the forest-tundra ecotone of the North Fennoscandian inland, summer and winter temperatures have increased by two to three centigrades since 1965, which is expected to result in major vegetation changes. To document the expected expansion of woodlands and scrublands and its impact on the arctic vegetation, we repeated a vegetation transect study conducted in 1976 in the Darju, spanning from woodland to a summit, 200 m above the tree line. Contrary to our expectations, tree line movement was not detected, and there was no increase in willows or shrubby mountain birches, either. Nevertheless, the stability of tundra was apparent. Small-sized, poorly competing arctic species had declined, lichen cover had decreased, and vascular plants, especially evergreen ericoid dwarf shrubs, had gained ground. The novel climate seems to favour competitive clonal species and species thriving in closed vegetation, creating a community hostile for seedling establishment, but equally hostile for many arctic species, too. Preventing trees and shrubs from invading the tundra is thus not sufficient for conserving arctic biota in the changing climate. The only dependable cure is to stop the global warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Coordinated responses of soil communities to elevation in three subarctic vegetation types.\n \n \n \n \n\n\n \n Veen, G. F. (.; De Long, J. R.; Kardol, P.; Sundqvist, M. K.; Snoek, L. B.; and Wardle, D. A.\n\n\n \n\n\n\n Oikos, 126(11): 1586–1599. 2017.\n _eprint: https://nsojournals.onlinelibrary.wiley.com/doi/pdf/10.1111/oik.04158\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{veen_coordinated_2017,\n\ttitle = {Coordinated responses of soil communities to elevation in three subarctic vegetation types},\n\tvolume = {126},\n\tcopyright = {© 2017 The Authors},\n\tissn = {1600-0706},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.04158},\n\tdoi = {10.1111/oik.04158},\n\tabstract = {Global warming has begun to have a major impact on the species composition and functioning of plant and soil communities. However, long-term community and ecosystem responses to increased temperature are still poorly understood. In this study, we used a well-established elevational gradient in northern Sweden to elucidate how plant, microbial and nematode communities shift with elevation and associated changes in temperature in three highly contrasting vegetation types (i.e. heath, meadow and Salix vegetation). We found that responses of both the abundance and composition of microbial and nematode communities to elevation differed greatly among the vegetation types. Within vegetation types, changes with elevation of plant, microbial and nematode communities were mostly linked at fine levels of taxonomic resolution, but this pattern disappeared when coarser functional group levels were considered. Further, nematode communities shifted towards more conservative nutrient cycling strategies with increasing elevation in heath and meadow vegetation. Conversely, in Salix vegetation microbial communities with conservative strategies were most pronounced at the mid-elevation. These results provide limited support for increasing conservative nutrient cycling strategies at higher elevation (i.e. with a harsher climate). Our findings indicate that climate-induced changes in plant community composition may greatly modify or counteract the impact of climate change on soil communities. Therefore, to better understand and predict ecosystem responses to climate change, it will be crucial to consider vegetation type and its specific interactions with soil communities.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2024-03-27},\n\tjournal = {Oikos},\n\tauthor = {Veen, G. F. (Ciska) and De Long, Jonathan R. and Kardol, Paul and Sundqvist, Maja K. and Snoek, L. Basten and Wardle, David A.},\n\tyear = {2017},\n\tnote = {\\_eprint: https://nsojournals.onlinelibrary.wiley.com/doi/pdf/10.1111/oik.04158},\n\tkeywords = {\\#nosource},\n\tpages = {1586--1599},\n}\n\n\n\n\n\n Global warming has begun to have a major impact on the species composition and functioning of plant and soil communities. However, long-term community and ecosystem responses to increased temperature are still poorly understood. In this study, we used a well-established elevational gradient in northern Sweden to elucidate how plant, microbial and nematode communities shift with elevation and associated changes in temperature in three highly contrasting vegetation types (i.e. heath, meadow and Salix vegetation). We found that responses of both the abundance and composition of microbial and nematode communities to elevation differed greatly among the vegetation types. Within vegetation types, changes with elevation of plant, microbial and nematode communities were mostly linked at fine levels of taxonomic resolution, but this pattern disappeared when coarser functional group levels were considered. Further, nematode communities shifted towards more conservative nutrient cycling strategies with increasing elevation in heath and meadow vegetation. Conversely, in Salix vegetation microbial communities with conservative strategies were most pronounced at the mid-elevation. These results provide limited support for increasing conservative nutrient cycling strategies at higher elevation (i.e. with a harsher climate). Our findings indicate that climate-induced changes in plant community composition may greatly modify or counteract the impact of climate change on soil communities. Therefore, to better understand and predict ecosystem responses to climate change, it will be crucial to consider vegetation type and its specific interactions with soil communities.\n
\n\n\n\n \n\n \n \n \n \n \n \n Potential contributions of root decomposition to the nitrogen cycle in arctic forest and tundra.\n \n \n \n \n\n\n \n Träger, S.; Milbau, A.; and Wilson, S. D.\n\n\n \n\n\n\n Ecology and Evolution, 7(24): 11021–11032. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.3522\n\n\n\n
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\n\n\n@article{trager_potential_2017,\n\ttitle = {Potential contributions of root decomposition to the nitrogen cycle in arctic forest and tundra},\n\tvolume = {7},\n\tcopyright = {© 2017 The Authors. Ecology and Evolution published by John Wiley \\& Sons Ltd.},\n\tissn = {2045-7758},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.3522},\n\tdoi = {10.1002/ece3.3522},\n\tabstract = {Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely observed increase in woody vegetation that accompanies climate change in the Arctic. We combined measurements of root production from minirhizotron images with tissue analysis of roots from differing root diameter and color classes to obtain potential N input following decomposition. In addition, we tested for changes in N concentration of roots during early stages of decomposition, and investigated whether vegetation type (forest or tundra) affected changes in tissue N concentration during decomposition. For completeness, we also present respective measurements of leaves. The potential N input from roots was twofold greater in forest than in tundra, mainly due to greater root production in forest. Potential N input varied with root diameter and color, but this variation tended to be similar in forest and tundra. As for roots, the potential N input from leaves was significantly greater in forest than in tundra. Vegetation type had no effect on changes in root or leaf N concentration after 1 year of decomposition. Our results suggest that shifts in vegetation that accompany climate change in the Arctic will likely increase plant-associated potential N input both belowground and aboveground. In contrast, shifts in vegetation might not alter changes in tissue N concentration during early stages of decomposition. Overall, differences between forest and tundra in potential contribution of decomposing roots to the N cycle reinforce differences between habitats that occur for leaves.},\n\tlanguage = {en},\n\tnumber = {24},\n\turldate = {2024-03-27},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Träger, Sabrina and Milbau, Ann and Wilson, Scott D.},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.3522},\n\tkeywords = {\\#nosource, home-field advantage, litter quality, minirhizotron, nitrogen content, plant litter, reciprocal transplant experiment, root production},\n\tpages = {11021--11032},\n}\n\n\n\n\n\n Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely observed increase in woody vegetation that accompanies climate change in the Arctic. We combined measurements of root production from minirhizotron images with tissue analysis of roots from differing root diameter and color classes to obtain potential N input following decomposition. In addition, we tested for changes in N concentration of roots during early stages of decomposition, and investigated whether vegetation type (forest or tundra) affected changes in tissue N concentration during decomposition. For completeness, we also present respective measurements of leaves. The potential N input from roots was twofold greater in forest than in tundra, mainly due to greater root production in forest. Potential N input varied with root diameter and color, but this variation tended to be similar in forest and tundra. As for roots, the potential N input from leaves was significantly greater in forest than in tundra. Vegetation type had no effect on changes in root or leaf N concentration after 1 year of decomposition. Our results suggest that shifts in vegetation that accompany climate change in the Arctic will likely increase plant-associated potential N input both belowground and aboveground. In contrast, shifts in vegetation might not alter changes in tissue N concentration during early stages of decomposition. Overall, differences between forest and tundra in potential contribution of decomposing roots to the N cycle reinforce differences between habitats that occur for leaves.\n
\n\n\n\n \n\n \n \n \n \n \n \n Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands.\n \n \n \n \n\n\n \n Tietjen, B.; Schlaepfer, D. R.; Bradford, J. B.; Lauenroth, W. K.; Hall, S. A.; Duniway, M. C.; Hochstrasser, T.; Jia, G.; Munson, S. M.; Pyke, D. A.; and Wilson, S. D.\n\n\n \n\n\n\n Global Change Biology, 23(7): 2743–2754. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13598\n\n\n\n
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\n\n\n@article{tietjen_climate_2017,\n\ttitle = {Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands},\n\tvolume = {23},\n\tcopyright = {© 2017 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13598},\n\tdoi = {10.1111/gcb.13598},\n\tabstract = {Drylands occur worldwide and are particularly vulnerable to climate change because dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability and change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding. We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation. Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change-induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, that is, leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water-limited ecosystems.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-27},\n\tjournal = {Global Change Biology},\n\tauthor = {Tietjen, Britta and Schlaepfer, Daniel R. and Bradford, John B. and Lauenroth, William K. and Hall, Sonia A. and Duniway, Michael C. and Hochstrasser, Tamara and Jia, Gensuo and Munson, Seth M. and Pyke, David A. and Wilson, Scott D.},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.13598},\n\tkeywords = {\\#nosource, direct and indirect effects, drought risk, ecohydrological model, shrub encroachment, soil water availability, vegetation impacts},\n\tpages = {2743--2754},\n}\n\n\n\n\n\n Drylands occur worldwide and are particularly vulnerable to climate change because dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability and change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding. We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation. Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change-induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, that is, leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water-limited ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Temperature Dependence of Apparent Respiratory Quotients and Oxygen Penetration Depth in Contrasting Lake Sediments.\n \n \n \n \n\n\n \n Sobek, S.; Gudasz, C.; Koehler, B.; Tranvik, L. J.; Bastviken, D.; and Morales-Pineda, M.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 122(11): 3076–3087. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2017JG003833\n\n\n\n
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\n\n\n@article{sobek_temperature_2017,\n\ttitle = {Temperature {Dependence} of {Apparent} {Respiratory} {Quotients} and {Oxygen} {Penetration} {Depth} in {Contrasting} {Lake} {Sediments}},\n\tvolume = {122},\n\tcopyright = {©2017. American Geophysical Union. All Rights Reserved.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2017JG003833},\n\tdoi = {10.1002/2017JG003833},\n\tabstract = {Lake sediments constitute an important compartment in the carbon cycle of lakes, by burying carbon over geological timescales and by production and emission of greenhouse gases. The degradation of organic carbon (OC) in lake sediments is linked to both temperature and oxygen (O2), but the interactive nature of this regulation has not been studied in lake sediments in a quantitative way. We present the first systematic investigation of the effects of temperature on the apparent respiratory quotient (RQ, i.e., the molar ratio between carbon dioxide (CO2) production and O2 consumption) in two contrasting lake sediments. Laboratory incubations of sediment cores of a humic lake and an eutrophic lake across a 1–21°C temperature gradient over 157 days revealed that both CO2 production and O2 consumption were positively, exponentially, and similarly dependent on temperature. The apparent RQ differed significantly between the lake sediments (0.63 ± 0.26 and 0.99 ± 0.28 in the humic and the eutrophic lake, respectively; mean ± SD) and was significantly and positively related to temperature. The O2 penetration depth into the sediment varied by a factor of 2 over the 1–21°C temperature range and was significantly, negatively, and similarly related to temperature in both lake sediments. Accordingly, increasing temperature may influence the overall extent of OC degradation in lake sediments by limiting O2 supply to aerobic microbial respiration to the topmost sediment layer, resulting in a concomitant shift to less effective anaerobic degradation pathways. This suggests that temperature may represent a key controlling factor of the OC burial efficiency in lake sediments.},\n\tlanguage = {sv},\n\tnumber = {11},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Sobek, Sebastian and Gudasz, Cristian and Koehler, Birgit and Tranvik, Lars J. and Bastviken, David and Morales-Pineda, María},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2017JG003833},\n\tkeywords = {\\#nosource, 0408 Benthic processes, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, 0439 Ecosystems: structure and dynamics, 0458 Limnology, Limnology, aquatic biogeochemistry, limnology, respiration, sediment},\n\tpages = {3076--3087},\n}\n\n\n\n\n\n Lake sediments constitute an important compartment in the carbon cycle of lakes, by burying carbon over geological timescales and by production and emission of greenhouse gases. The degradation of organic carbon (OC) in lake sediments is linked to both temperature and oxygen (O2), but the interactive nature of this regulation has not been studied in lake sediments in a quantitative way. We present the first systematic investigation of the effects of temperature on the apparent respiratory quotient (RQ, i.e., the molar ratio between carbon dioxide (CO2) production and O2 consumption) in two contrasting lake sediments. Laboratory incubations of sediment cores of a humic lake and an eutrophic lake across a 1–21°C temperature gradient over 157 days revealed that both CO2 production and O2 consumption were positively, exponentially, and similarly dependent on temperature. The apparent RQ differed significantly between the lake sediments (0.63 ± 0.26 and 0.99 ± 0.28 in the humic and the eutrophic lake, respectively; mean ± SD) and was significantly and positively related to temperature. The O2 penetration depth into the sediment varied by a factor of 2 over the 1–21°C temperature range and was significantly, negatively, and similarly related to temperature in both lake sediments. Accordingly, increasing temperature may influence the overall extent of OC degradation in lake sediments by limiting O2 supply to aerobic microbial respiration to the topmost sediment layer, resulting in a concomitant shift to less effective anaerobic degradation pathways. This suggests that temperature may represent a key controlling factor of the OC burial efficiency in lake sediments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Interactive Effects Between Reindeer and Habitat Fertility Drive Soil Nutrient Availabilities in Arctic Tundra.\n \n \n \n \n\n\n \n Sitters, J.; te Beest, M.; Cherif, M.; Giesler, R.; and Olofsson, J.\n\n\n \n\n\n\n Ecosystems, 20(7): 1266–1277. November 2017.\n \n\n\n\n
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\n\n\n@article{sitters_interactive_2017,\n\ttitle = {Interactive {Effects} {Between} {Reindeer} and {Habitat} {Fertility} {Drive} {Soil} {Nutrient} {Availabilities} in {Arctic} {Tundra}},\n\tvolume = {20},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-017-0108-1},\n\tdoi = {10.1007/s10021-017-0108-1},\n\tabstract = {Herbivores impact nutrient availability and cycling, and the net effect of herbivory on soil nutrients is generally assumed to be positive in nutrient-rich environments and negative in nutrient-poor ones. This is, however, far from a uniform pattern, and there is a recognized need to investigate any interactive effects of herbivory and habitat fertility (i.e., plant C/N ratios) on soil nutrient availabilities. We determined long-term effects of reindeer on soil extractable nitrogen (N) and phosphorus (P) and their net mineralization rates along a fertility gradient of plant carbon (C) to N and P ratios in arctic tundra. Our results showed that reindeer had a positive effect on soil N in the more nutrient-poor sites and a negative effect on soil P in the more nutrient-rich sites, which contrasts from the general consensus. The increase in N availability was linked to a decrease in plant and litter C/N ratios, suggesting that a shift in vegetation composition toward more graminoids favors higher N cycling. Soil P availability was not as closely linked to the vegetation and is likely regulated more by herbivore-induced changes in soil physical and chemical properties. The changes in soil extractable N and P resulted in higher soil N/P ratios, suggesting that reindeer could drive the vegetation toward P-limitation. This research highlights the importance of including both the elements N and P and conducting studies along environmental gradients in order to better understand the interactive effects of herbivory and habitat fertility on nutrient cycling and primary production.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Sitters, Judith and te Beest, Mariska and Cherif, Mehdi and Giesler, Reiner and Olofsson, Johan},\n\tmonth = nov,\n\tyear = {2017},\n\tkeywords = {\\#nosource, carbon, decomposition, grazing, herbivory, litter, microbial mineralization, nitrogen, nutrient cycling, phosphorus, plant stoichiometry},\n\tpages = {1266--1277},\n}\n\n\n\n\n\n Herbivores impact nutrient availability and cycling, and the net effect of herbivory on soil nutrients is generally assumed to be positive in nutrient-rich environments and negative in nutrient-poor ones. This is, however, far from a uniform pattern, and there is a recognized need to investigate any interactive effects of herbivory and habitat fertility (i.e., plant C/N ratios) on soil nutrient availabilities. We determined long-term effects of reindeer on soil extractable nitrogen (N) and phosphorus (P) and their net mineralization rates along a fertility gradient of plant carbon (C) to N and P ratios in arctic tundra. Our results showed that reindeer had a positive effect on soil N in the more nutrient-poor sites and a negative effect on soil P in the more nutrient-rich sites, which contrasts from the general consensus. The increase in N availability was linked to a decrease in plant and litter C/N ratios, suggesting that a shift in vegetation composition toward more graminoids favors higher N cycling. Soil P availability was not as closely linked to the vegetation and is likely regulated more by herbivore-induced changes in soil physical and chemical properties. The changes in soil extractable N and P resulted in higher soil N/P ratios, suggesting that reindeer could drive the vegetation toward P-limitation. This research highlights the importance of including both the elements N and P and conducting studies along environmental gradients in order to better understand the interactive effects of herbivory and habitat fertility on nutrient cycling and primary production.\n
\n\n\n\n \n\n \n \n \n \n \n \n Large Lakes Dominate CO2 Evasion From Lakes in an Arctic Catchment.\n \n \n \n \n\n\n \n Rocher-Ros, G.; Giesler, R.; Lundin, E.; Salimi, S.; Jonsson, A.; and Karlsson, J.\n\n\n \n\n\n\n Geophysical Research Letters, 44(24): 12,254–12,261. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL076146\n\n\n\n
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\n\n\n@article{rocher-ros_large_2017,\n\ttitle = {Large {Lakes} {Dominate} {CO2} {Evasion} {From} {Lakes} in an {Arctic} {Catchment}},\n\tvolume = {44},\n\tcopyright = {©2017. American Geophysical Union. All Rights Reserved.},\n\tissn = {1944-8007},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2017GL076146},\n\tdoi = {10.1002/2017GL076146},\n\tabstract = {CO2 evasion from freshwater lakes is an important component of the carbon cycle. However, the relative contribution from different lake sizes may vary, since several parameters underlying CO2 flux are size dependent. Here we estimated the annual lake CO2 evasion from a catchment in northern Sweden encompassing about 30,000 differently sized lakes. We show that areal CO2 fluxes decreased rapidly with lake size, but this was counteracted by the greater overall coverage of larger lakes. As a result, total efflux increased with lake size and the single largest lake in the catchment dominated the CO2 evasion (53\\% of all CO2 evaded). By contrast, the contribution from the smallest ponds (about 27,000) was minor ({\\textless}6\\%). Our results emphasize the importance of accounting for both CO2 flux rates and areal contribution of various sized lakes in assessments of CO2 evasion at the landscape scale.},\n\tlanguage = {en},\n\tnumber = {24},\n\turldate = {2024-03-27},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Rocher-Ros, Gerard and Giesler, Reiner and Lundin, Erik and Salimi, Shokoufeh and Jonsson, Anders and Karlsson, Jan},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL076146},\n\tkeywords = {\\#nosource, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, 0458 Limnology, 0746 Lakes, 0748 Ponds, lake CO2 evasion, lake size distribution, upscaling C cycle},\n\tpages = {12,254--12,261},\n}\n\n\n\n\n\n CO2 evasion from freshwater lakes is an important component of the carbon cycle. However, the relative contribution from different lake sizes may vary, since several parameters underlying CO2 flux are size dependent. Here we estimated the annual lake CO2 evasion from a catchment in northern Sweden encompassing about 30,000 differently sized lakes. We show that areal CO2 fluxes decreased rapidly with lake size, but this was counteracted by the greater overall coverage of larger lakes. As a result, total efflux increased with lake size and the single largest lake in the catchment dominated the CO2 evasion (53% of all CO2 evaded). By contrast, the contribution from the smallest ponds (about 27,000) was minor (\\textless6%). Our results emphasize the importance of accounting for both CO2 flux rates and areal contribution of various sized lakes in assessments of CO2 evasion at the landscape scale.\n
\n\n\n\n \n\n \n \n \n \n \n \n Climate change effects on the stability and chemistry of soil organic carbon pools in a subalpine grassland.\n \n \n \n \n\n\n \n Puissant, J.; Mills, R. T. E.; Robroek, B. J. M.; Gavazov, K.; Perrette, Y.; De Danieli, S.; Spiegelberger, T.; Buttler, A.; Brun, J.; and Cécillon, L.\n\n\n \n\n\n\n Biogeochemistry, 132(1): 123–139. January 2017.\n \n\n\n\n
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\n\n\n@article{puissant_climate_2017,\n\ttitle = {Climate change effects on the stability and chemistry of soil organic carbon pools in a subalpine grassland},\n\tvolume = {132},\n\tissn = {1573-515X},\n\turl = {https://doi.org/10.1007/s10533-016-0291-8},\n\tdoi = {10.1007/s10533-016-0291-8},\n\tabstract = {Mountain soils stock large quantities of carbon as particulate organic matter that may be highly vulnerable to climate change. To explore potential shifts in soil organic matter (SOM) form and stability under climate change (warming and reduced precipitations), we studied the dynamics of SOM pools of a mountain grassland in the Swiss Jura as part of a climate manipulation experiment. The climate manipulation (elevational soil transplantation) was set up in October 2009 and simulated two realistic climate change scenarios. After 4 years of manipulation, we performed SOM physical fractionation to extract SOM fractions corresponding to specific turnover rates, in winter and in summer. Soil organic matter fraction chemistry was studied with ultraviolet, 3D fluorescence, and mid-infrared spectroscopies. The most labile SOM fractions showed high intra-annual dynamics (amounts and chemistry) mediated via the seasonal changes of fresh plant debris inputs and confirming their high contribution to the microbial loop. Our climate change manipulation modified the chemical differences between free and intra-aggregate organic matter, suggesting a modification of soil macro-aggregates dynamics. Interestingly, the 4-year climate manipulation affected directly the SOM dynamics, with a decrease in organic C bulk soil content, resulting from significant C-losses in the mineral-associated SOM fraction (MAOM), the most stable form of SOM. This SOC decrease was associated with a decrease in clay content, above- and belowground plants biomass, soil microbial biomass and activity. The combination of these climate changes effects on the plant–soil system could have led to increase C-losses from the MAOM fraction through clay-SOM washing out and DOC leaching in this subalpine grassland.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Biogeochemistry},\n\tauthor = {Puissant, Jérémy and Mills, Robert T. E. and Robroek, Bjorn J. M. and Gavazov, Konstantin and Perrette, Yves and De Danieli, Sébastien and Spiegelberger, Thomas and Buttler, Alexandre and Brun, Jean-Jacques and Cécillon, Lauric},\n\tmonth = jan,\n\tyear = {2017},\n\tkeywords = {\\#nosource, 3D fluorescence spectroscopy, Infrared spectroscopy, Mineral associated organic matter, Particulate organic matter, Water extractable organic carbon},\n\tpages = {123--139},\n}\n\n\n\n\n\n Mountain soils stock large quantities of carbon as particulate organic matter that may be highly vulnerable to climate change. To explore potential shifts in soil organic matter (SOM) form and stability under climate change (warming and reduced precipitations), we studied the dynamics of SOM pools of a mountain grassland in the Swiss Jura as part of a climate manipulation experiment. The climate manipulation (elevational soil transplantation) was set up in October 2009 and simulated two realistic climate change scenarios. After 4 years of manipulation, we performed SOM physical fractionation to extract SOM fractions corresponding to specific turnover rates, in winter and in summer. Soil organic matter fraction chemistry was studied with ultraviolet, 3D fluorescence, and mid-infrared spectroscopies. The most labile SOM fractions showed high intra-annual dynamics (amounts and chemistry) mediated via the seasonal changes of fresh plant debris inputs and confirming their high contribution to the microbial loop. Our climate change manipulation modified the chemical differences between free and intra-aggregate organic matter, suggesting a modification of soil macro-aggregates dynamics. Interestingly, the 4-year climate manipulation affected directly the SOM dynamics, with a decrease in organic C bulk soil content, resulting from significant C-losses in the mineral-associated SOM fraction (MAOM), the most stable form of SOM. This SOC decrease was associated with a decrease in clay content, above- and belowground plants biomass, soil microbial biomass and activity. The combination of these climate changes effects on the plant–soil system could have led to increase C-losses from the MAOM fraction through clay-SOM washing out and DOC leaching in this subalpine grassland.\n
\n\n\n\n \n\n \n \n \n \n \n \n The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition.\n \n \n \n \n\n\n \n Öquist, M. G.; Erhagen, B.; Haei, M.; Sparrman, T.; Ilstedt, U.; Schleucher, J.; and Nilsson, M. B.\n\n\n \n\n\n\n Plant and Soil, 414(1): 113–125. May 2017.\n \n\n\n\n
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\n\n\n@article{oquist_effect_2017,\n\ttitle = {The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition},\n\tvolume = {414},\n\tissn = {1573-5036},\n\turl = {https://doi.org/10.1007/s11104-016-3104-x},\n\tdoi = {10.1007/s11104-016-3104-x},\n\tabstract = {Mineralization of soil organic matter (SOM) constitutes a major carbon flux to the atmosphere. The carbon use efficiency (CUE) of the saprotrophic microorganisms mineralizing SOM is integral for soil carbon dynamics. Here we investigate how the CUE is affected by temperature, metabolic conditions, and the molecular complexity of the substrate.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2024-03-27},\n\tjournal = {Plant and Soil},\n\tauthor = {Öquist, Mats G. and Erhagen, Björn and Haei, Mahsa and Sparrman, Tobias and Ilstedt, Ulrik and Schleucher, Jürgen and Nilsson, Mats B.},\n\tmonth = may,\n\tyear = {2017},\n\tkeywords = {\\#nosource, 13C–substrate, Boreal forest soil, Carbon use efficiency (CUE), Decomposition, Metabolic condition, NMR},\n\tpages = {113--125},\n}\n\n\n\n\n\n Mineralization of soil organic matter (SOM) constitutes a major carbon flux to the atmosphere. The carbon use efficiency (CUE) of the saprotrophic microorganisms mineralizing SOM is integral for soil carbon dynamics. Here we investigate how the CUE is affected by temperature, metabolic conditions, and the molecular complexity of the substrate.\n
\n\n\n\n \n\n \n \n \n \n \n \n Mountain roads shift native and non-native plant species' ranges.\n \n \n \n \n\n\n \n Lembrechts, J. J.; Alexander, J. M.; Cavieres, L. A.; Haider, S.; Lenoir, J.; Kueffer, C.; McDougall, K.; Naylor, B. J.; Nuñez, M. A.; Pauchard, A.; Rew, L. J.; Nijs, I.; and Milbau, A.\n\n\n \n\n\n\n Ecography, 40(3): 353–364. 2017.\n _eprint: https://nsojournals.onlinelibrary.wiley.com/doi/pdf/10.1111/ecog.02200\n\n\n\n
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\n\n\n@article{lembrechts_mountain_2017,\n\ttitle = {Mountain roads shift native and non-native plant species' ranges},\n\tvolume = {40},\n\tcopyright = {© 2016 The Authors},\n\tissn = {1600-0587},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/ecog.02200},\n\tdoi = {10.1111/ecog.02200},\n\tabstract = {Roads are known to act as corridors for dispersal of plant species. With their variable microclimate, role as corridors for species movement and reoccurring disturbance events, they show several characteristics that might influence range dynamics of both native and non-native species. Previous research on plant species ranges in mountains however seldom included the effects of roads. To study how ranges of native and non-native species differ between roads and adjacent vegetation, we used a global dataset of plant species composition along mountain roads. We compared average elevation and range width of species, and used generalized linear mixed models (GLMMs) to compile their range optimum and amplitude. We then explored differences between roadside and adjacent plots based on a species’ origin (native vs non-native) and nitrogen and temperature affinity. Most non-native species had on average higher elevational ranges and broader amplitudes in roadsides. Higher optima for non-native species were associated with high nitrogen and temperature affinity. While lowland native species showed patterns comparable to those in non-native species, highland native species had significantly lower elevational ranges in roadsides compared to the adjacent vegetation. We conclude that roadsides indeed change the elevational ranges of a variety of species. These changes are not limited to the expansion of non-native species along mountain roads, but also include both upward and downward changes in ranges of native species. Roadsides may thus facilitate upward range shifts, for instance related to climate change, and they could serve as corridors to facilitate migration of alpine species between adjacent high-elevation areas. We recommend including the effects of mountain roads in species distribution models to fine-tune the predictions of range changes in a warming climate.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Ecography},\n\tauthor = {Lembrechts, Jonas J. and Alexander, Jake M. and Cavieres, Lohengrin A. and Haider, Sylvia and Lenoir, Jonathan and Kueffer, Christoph and McDougall, Keith and Naylor, Bridgett J. and Nuñez, Martín A. and Pauchard, Aníbal and Rew, Lisa J. and Nijs, Ivan and Milbau, Ann},\n\tyear = {2017},\n\tnote = {\\_eprint: https://nsojournals.onlinelibrary.wiley.com/doi/pdf/10.1111/ecog.02200},\n\tkeywords = {\\#nosource, Species distributions, disturbance, mountain roads, native and non-native species, nitrogen and temperature affinity, plant invasion, range shifts},\n\tpages = {353--364},\n}\n\n\n\n\n\n Roads are known to act as corridors for dispersal of plant species. With their variable microclimate, role as corridors for species movement and reoccurring disturbance events, they show several characteristics that might influence range dynamics of both native and non-native species. Previous research on plant species ranges in mountains however seldom included the effects of roads. To study how ranges of native and non-native species differ between roads and adjacent vegetation, we used a global dataset of plant species composition along mountain roads. We compared average elevation and range width of species, and used generalized linear mixed models (GLMMs) to compile their range optimum and amplitude. We then explored differences between roadside and adjacent plots based on a species’ origin (native vs non-native) and nitrogen and temperature affinity. Most non-native species had on average higher elevational ranges and broader amplitudes in roadsides. Higher optima for non-native species were associated with high nitrogen and temperature affinity. While lowland native species showed patterns comparable to those in non-native species, highland native species had significantly lower elevational ranges in roadsides compared to the adjacent vegetation. We conclude that roadsides indeed change the elevational ranges of a variety of species. These changes are not limited to the expansion of non-native species along mountain roads, but also include both upward and downward changes in ranges of native species. Roadsides may thus facilitate upward range shifts, for instance related to climate change, and they could serve as corridors to facilitate migration of alpine species between adjacent high-elevation areas. We recommend including the effects of mountain roads in species distribution models to fine-tune the predictions of range changes in a warming climate.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lake responses to long-term disturbances and management practices.\n \n \n \n \n\n\n \n Lau, D. C. P.; Vrede, T.; and Goedkoop, W.\n\n\n \n\n\n\n Freshwater Biology, 62(4): 792–806. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.12902\n\n\n\n
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\n\n\n@article{lau_lake_2017,\n\ttitle = {Lake responses to long-term disturbances and management practices},\n\tvolume = {62},\n\tcopyright = {© 2017 John Wiley \\& Sons Ltd},\n\tissn = {1365-2427},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.12902},\n\tdoi = {10.1111/fwb.12902},\n\tabstract = {Long-term human-induced disturbances such as acidification and algal invasions, and management practices such as liming, are known to alter community structure and biodiversity of north temperate lakes. We assessed if they impacted on the trophic ecology and production of apex consumers (i.e. fish) and the overall food-chain length (FCL) of boreal lake ecosystems, and if these functional responses were consistent with the biodiversity changes. We hypothesise that fish production and FCL decrease with decreasing species biodiversity of lake communities, and that long-term environmental perturbations will alter the relative reliance of fish on littoral versus pelagic trophic pathways and their ontogenetic changes in trophic position (TP). We analysed long-term data and stable isotopes of multiple organismal groups – phytoplankton, zooplankton, littoral and sub-littoral/profundal macroinvertebrates, and fish – collected from small boreal lakes that have been subjected to acidification, lime application and/or algal invasion by Gonyostomum semen. Species biodiversity, FCL and fish production (i.e. growth and catch-per-unit-effort) were compared among three lake categories, i.e. acidic, limed and circumneutral (reference) lakes, within each three lakes were selected. Fish TP and their relative littoral versus pelagic reliance were estimated based on stable nitrogen and carbon isotopes respectively. Gonyostomum contributed to 77–98\\% phytoplankton biovolume in acidic lakes, {\\textless}1–79\\% in limed lakes and 0–30\\% in circumneutral lakes. Its prevalence was correlated with total organic carbon concentration but not with lake pH, alkalinity or any other environmental variable. Diversity and evenness of phytoplankton, macroinvertebrates and fish generally decreased with increasing Gonyostomum biovolume, such that biodiversity was higher in circumneutral and limed lakes than in acidic lakes. Isotopic data revealed that FCL was shortest in limed lakes (3.94 ± 0.08; least-squares mean ± SE), intermediate in acidic lakes (4.19 ± 0.07) and longest in circumneutral lakes (4.38 ± 0.08). Limed lakes also had the lowest fish growth and CPUE. Overall littoral reliance of fish was higher in acidic lakes (0.53 ± 0.03) than in limed lakes (0.42 ± 0.02) and circumneutral lakes (0.30 ± 0.02), suggesting that fish production and FCL there could have been sustained by the increased littoral reliance when pelagic trophic pathways were hindered by Gonyostomum invasion. European perch (Perca fluviatilis), the most common fish in the lakes, showed faster TP increases in acidic and limed lakes, likely due to their earlier ontogenetic shift from zooplanktivory to zoobenthivory and/or piscivory. Overall, our findings indicate that long-term disturbances (i.e. acidification and algal invasions) and management practices (i.e. liming) can (i) induce contrasting responses in biodiversity, FCL and fish production of boreal lakes; (ii) be the primary driver of FCL variation among small and similar-size ecosystems; and (iii) alter the trophic ecology (i.e. TP change during ontogeny and littoral reliance) of key fish species. The trophic ecology and production of apex consumers and FCL together can provide useful integrated proxies for ecosystem functioning, which can supplement traditional biodiversity measurements for more robust environmental assessments.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Freshwater Biology},\n\tauthor = {Lau, Danny C. P. and Vrede, Tobias and Goedkoop, Willem},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/fwb.12902},\n\tkeywords = {\\#nosource, Acidification, Liming, acidification, biodieversity, fish, food webs, invasions, liming, stable isotopes},\n\tpages = {792--806},\n}\n\n\n\n\n\n Long-term human-induced disturbances such as acidification and algal invasions, and management practices such as liming, are known to alter community structure and biodiversity of north temperate lakes. We assessed if they impacted on the trophic ecology and production of apex consumers (i.e. fish) and the overall food-chain length (FCL) of boreal lake ecosystems, and if these functional responses were consistent with the biodiversity changes. We hypothesise that fish production and FCL decrease with decreasing species biodiversity of lake communities, and that long-term environmental perturbations will alter the relative reliance of fish on littoral versus pelagic trophic pathways and their ontogenetic changes in trophic position (TP). We analysed long-term data and stable isotopes of multiple organismal groups – phytoplankton, zooplankton, littoral and sub-littoral/profundal macroinvertebrates, and fish – collected from small boreal lakes that have been subjected to acidification, lime application and/or algal invasion by Gonyostomum semen. Species biodiversity, FCL and fish production (i.e. growth and catch-per-unit-effort) were compared among three lake categories, i.e. acidic, limed and circumneutral (reference) lakes, within each three lakes were selected. Fish TP and their relative littoral versus pelagic reliance were estimated based on stable nitrogen and carbon isotopes respectively. Gonyostomum contributed to 77–98% phytoplankton biovolume in acidic lakes, \\textless1–79% in limed lakes and 0–30% in circumneutral lakes. Its prevalence was correlated with total organic carbon concentration but not with lake pH, alkalinity or any other environmental variable. Diversity and evenness of phytoplankton, macroinvertebrates and fish generally decreased with increasing Gonyostomum biovolume, such that biodiversity was higher in circumneutral and limed lakes than in acidic lakes. Isotopic data revealed that FCL was shortest in limed lakes (3.94 ± 0.08; least-squares mean ± SE), intermediate in acidic lakes (4.19 ± 0.07) and longest in circumneutral lakes (4.38 ± 0.08). Limed lakes also had the lowest fish growth and CPUE. Overall littoral reliance of fish was higher in acidic lakes (0.53 ± 0.03) than in limed lakes (0.42 ± 0.02) and circumneutral lakes (0.30 ± 0.02), suggesting that fish production and FCL there could have been sustained by the increased littoral reliance when pelagic trophic pathways were hindered by Gonyostomum invasion. European perch (Perca fluviatilis), the most common fish in the lakes, showed faster TP increases in acidic and limed lakes, likely due to their earlier ontogenetic shift from zooplanktivory to zoobenthivory and/or piscivory. Overall, our findings indicate that long-term disturbances (i.e. acidification and algal invasions) and management practices (i.e. liming) can (i) induce contrasting responses in biodiversity, FCL and fish production of boreal lakes; (ii) be the primary driver of FCL variation among small and similar-size ecosystems; and (iii) alter the trophic ecology (i.e. TP change during ontogeny and littoral reliance) of key fish species. The trophic ecology and production of apex consumers and FCL together can provide useful integrated proxies for ecosystem functioning, which can supplement traditional biodiversity measurements for more robust environmental assessments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Utilising a Suite of Isotopic and Elemental Tracers to Constrain Cryoturbation Rates and Patterns in a Non-sorted Circle.\n \n \n \n \n\n\n \n Jelinski, N. A.; Yoo, K.; and Klaminder, J.\n\n\n \n\n\n\n Permafrost and Periglacial Processes, 28(4): 634–648. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.1944\n\n\n\n
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\n\n\n@article{jelinski_utilising_2017,\n\ttitle = {Utilising a {Suite} of {Isotopic} and {Elemental} {Tracers} to {Constrain} {Cryoturbation} {Rates} and {Patterns} in a {Non}-sorted {Circle}},\n\tvolume = {28},\n\tcopyright = {Copyright © 2017 John Wiley \\& Sons, Ltd.},\n\tissn = {1099-1530},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ppp.1944},\n\tdoi = {10.1002/ppp.1944},\n\tabstract = {The empirical quantification of rates of material movement in cryoturbated soils has lagged behind the physical and chemical characterisation of these materials. We applied a novel suite of elemental (C, Hg), stable isotope (13C) and radioisotope (137Cs, 210Pb, 14C, 10Be) tracers in conjunction with analytical and numerical models to constrain the rates and patterns of soil movement due to cryoturbation in a non-sorted circle (NSC) near Abisko, Sweden. We present the first observations of the variability of 10Be across a patterned-ground feature, which facilitate the interpretation of subsurface peaks in soil organic carbon, Hg and 13C and provide constraints on the surficial histories of cryoturbated materials. Apparent rates of surficial lateral movement across the NSC estimated from 137Cs and 210Pb (0–2.55 cm year−1) decreased with distance from its centre and were an order of magnitude greater than rates of subduction and subsurface movement estimated from 14C (0.04–0.27 cm year−1). Novel estimates of the original surficial residence times of cryoturbated parcels based on excess 10Be and Hg inventories ranged from 238 to 3940 years. Our results demonstrate the utility of the spatially explicit application of elemental and radioisotopic tracer suites to constrain cryoturbation rates in Arctic patterned ground. Copyright © 2017 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Permafrost and Periglacial Processes},\n\tauthor = {Jelinski, Nicolas A. and Yoo, Kyungsoo and Klaminder, Jonatan},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.1944},\n\tkeywords = {\\#nosource, 10Be, 137Cs, 14C, 210Pb, Cryoturbation, cryoturbation, non-sorted circle},\n\tpages = {634--648},\n}\n\n\n\n\n\n The empirical quantification of rates of material movement in cryoturbated soils has lagged behind the physical and chemical characterisation of these materials. We applied a novel suite of elemental (C, Hg), stable isotope (13C) and radioisotope (137Cs, 210Pb, 14C, 10Be) tracers in conjunction with analytical and numerical models to constrain the rates and patterns of soil movement due to cryoturbation in a non-sorted circle (NSC) near Abisko, Sweden. We present the first observations of the variability of 10Be across a patterned-ground feature, which facilitate the interpretation of subsurface peaks in soil organic carbon, Hg and 13C and provide constraints on the surficial histories of cryoturbated materials. Apparent rates of surficial lateral movement across the NSC estimated from 137Cs and 210Pb (0–2.55 cm year−1) decreased with distance from its centre and were an order of magnitude greater than rates of subduction and subsurface movement estimated from 14C (0.04–0.27 cm year−1). Novel estimates of the original surficial residence times of cryoturbated parcels based on excess 10Be and Hg inventories ranged from 238 to 3940 years. Our results demonstrate the utility of the spatially explicit application of elemental and radioisotopic tracer suites to constrain cryoturbation rates in Arctic patterned ground. Copyright © 2017 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contributions of terrestrial organic carbon to northern lake sediments.\n \n \n \n \n\n\n \n Gudasz, C.; Ruppenthal, M.; Kalbitz, K.; Cerli, C.; Fiedler, S.; Oelmann, Y.; Andersson, A.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography Letters, 2(6): 218–227. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10051\n\n\n\n
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\n\n\n@article{gudasz_contributions_2017,\n\ttitle = {Contributions of terrestrial organic carbon to northern lake sediments},\n\tvolume = {2},\n\tcopyright = {© 2017 The Author. Limnology and Oceanography Letters published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography},\n\tissn = {2378-2242},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10051},\n\tdoi = {10.1002/lol2.10051},\n\tabstract = {Sediments of northern lakes sequester large amounts of organic carbon (OC), but direct evidence of the relative importance of their sources is lacking. We used stable isotope ratios of nonexchangeable hydrogen (δ2Hn) in topsoil, algae, and surface sediments in order to measure the relative contribution of terrestrial OC in surface sediments of 14 mountainous arctic and lowland boreal lakes in Sweden. The terrestrial contribution to the sediment OC pool was on average 66\\% (range 46–80) and similar between arctic and boreal lakes. Proxies for the supply of terrestrial and algal OC explained trends in the relative contribution of terrestrial OC across lakes. However, the data suggest divergent predominant sources for terrestrial OC of sediments in Swedish lakes, with dissolved matter dominating in lowland boreal lakes and particulate OC in mountainous arctic lakes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2024-03-27},\n\tjournal = {Limnology and Oceanography Letters},\n\tauthor = {Gudasz, Cristian and Ruppenthal, Marc and Kalbitz, Karsten and Cerli, Chiara and Fiedler, Sabine and Oelmann, Yvonne and Andersson, August and Karlsson, Jan},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/lol2.10051},\n\tkeywords = {\\#nosource},\n\tpages = {218--227},\n}\n\n\n\n\n\n Sediments of northern lakes sequester large amounts of organic carbon (OC), but direct evidence of the relative importance of their sources is lacking. We used stable isotope ratios of nonexchangeable hydrogen (δ2Hn) in topsoil, algae, and surface sediments in order to measure the relative contribution of terrestrial OC in surface sediments of 14 mountainous arctic and lowland boreal lakes in Sweden. The terrestrial contribution to the sediment OC pool was on average 66% (range 46–80) and similar between arctic and boreal lakes. Proxies for the supply of terrestrial and algal OC explained trends in the relative contribution of terrestrial OC across lakes. However, the data suggest divergent predominant sources for terrestrial OC of sediments in Swedish lakes, with dissolved matter dominating in lowland boreal lakes and particulate OC in mountainous arctic lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Tracing Pb Pollution Penetration in Temperate Podzols.\n \n \n \n \n\n\n \n Ferro-Vázquez, C.; Pérez-Rodríguez, M.; Nóvoa-Muñoz, J. C.; Klaminder, J.; Bindler, R.; and Martínez Cortizas, A.\n\n\n \n\n\n\n Land Degradation & Development, 28(8): 2432–2445. 2017.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ldr.2777\n\n\n\n
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\n\n\n@article{ferro-vazquez_tracing_2017,\n\ttitle = {Tracing {Pb} {Pollution} {Penetration} in {Temperate} {Podzols}},\n\tvolume = {28},\n\tcopyright = {Copyright © 2017 John Wiley \\& Sons, Ltd.},\n\tissn = {1099-145X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ldr.2777},\n\tdoi = {10.1002/ldr.2777},\n\tabstract = {We combine high-resolution soil sampling with lead (Pb) analyses (concentrations and stable isotopes) in two temperate podzols, together with previous data obtained with selective Al and Fe dissolution techniques. We aim to assess how atmospheric Pb is incorporated into the soils during pedogenesis. Partial least squares modelling for Pb concentrations shows that the podzolization process has the largest effect on Pb concentration (80·3\\% of the variance). The proportion of inorganic secondary compounds, the input of fresh organic matter from the soil surface and the relative abundance of Fe versus Al are responsible for a small part of the Pb concentration variance. Lead isotopic composition (206Pb/207Pb ratios) depends on soil organic matter content either fresh/poorly humified (57·3\\% of the variance) or humified (24·7\\% of the variance). The Pb linked to inorganic compounds and the overall podzolization process play a minor role in isotopic signature (5·3 and 3·7\\% of the variance respectively). Soil pH appears to be the controlling variable of the different transport and retention mechanisms. The relatively low isotopic ratios observed in spodic horizons result from geogenic Pb released through the preferential dissolution of the isotopically distinct most weatherable minerals of the parent material in the eluvial horizons, which undergoes downward mobilization. An accurate knowledge of soil reactive components and formation mechanisms is essential to a correct diagnose of the scope of Pb pollution and a more effective design of remediation strategies. Copyright © 2017 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2024-03-27},\n\tjournal = {Land Degradation \\& Development},\n\tauthor = {Ferro-Vázquez, Cruz and Pérez-Rodríguez, Marta and Nóvoa-Muñoz, Juan Carlos and Klaminder, Jonatan and Bindler, Richard and Martínez Cortizas, Antonio},\n\tyear = {2017},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/ldr.2777},\n\tkeywords = {\\#nosource, Lead isotopes, Partial Least Squares modelling, atmospheric deposition, lead isotopes, partial least squares modelling, podzols},\n\tpages = {2432--2445},\n}\n\n\n\n\n\n We combine high-resolution soil sampling with lead (Pb) analyses (concentrations and stable isotopes) in two temperate podzols, together with previous data obtained with selective Al and Fe dissolution techniques. We aim to assess how atmospheric Pb is incorporated into the soils during pedogenesis. Partial least squares modelling for Pb concentrations shows that the podzolization process has the largest effect on Pb concentration (80·3% of the variance). The proportion of inorganic secondary compounds, the input of fresh organic matter from the soil surface and the relative abundance of Fe versus Al are responsible for a small part of the Pb concentration variance. Lead isotopic composition (206Pb/207Pb ratios) depends on soil organic matter content either fresh/poorly humified (57·3% of the variance) or humified (24·7% of the variance). The Pb linked to inorganic compounds and the overall podzolization process play a minor role in isotopic signature (5·3 and 3·7% of the variance respectively). Soil pH appears to be the controlling variable of the different transport and retention mechanisms. The relatively low isotopic ratios observed in spodic horizons result from geogenic Pb released through the preferential dissolution of the isotopically distinct most weatherable minerals of the parent material in the eluvial horizons, which undergoes downward mobilization. An accurate knowledge of soil reactive components and formation mechanisms is essential to a correct diagnose of the scope of Pb pollution and a more effective design of remediation strategies. Copyright © 2017 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome.\n \n \n \n \n\n\n \n Barrio, I. C.; Lindén, E.; Te Beest, M.; Olofsson, J.; Rocha, A.; Soininen, E. M.; Alatalo, J. M.; Andersson, T.; Asmus, A.; Boike, J.; Bråthen, K. A.; Bryant, J. P.; Buchwal, A.; Bueno, C. G.; Christie, K. S.; Denisova, Y. V.; Egelkraut, D.; Ehrich, D.; Fishback, L.; Forbes, B. C.; Gartzia, M.; Grogan, P.; Hallinger, M.; Heijmans, M. M. P. D.; Hik, D. S.; Hofgaard, A.; Holmgren, M.; Høye, T. T.; Huebner, D. C.; Jónsdóttir, I. S.; Kaarlejärvi, E.; Kumpula, T.; Lange, C. Y. M. J. G.; Lange, J.; Lévesque, E.; Limpens, J.; Macias-Fauria, M.; Myers-Smith, I.; van Nieukerken, E. J.; Normand, S.; Post, E. S.; Schmidt, N. M.; Sitters, J.; Skoracka, A.; Sokolov, A.; Sokolova, N.; Speed, J. D. M.; Street, L. E.; Sundqvist, M. K.; Suominen, O.; Tananaev, N.; Tremblay, J.; Urbanowicz, C.; Uvarov, S. A.; Watts, D.; Wilmking, M.; Wookey, P. A.; Zimmermann, H. H.; Zverev, V.; and Kozlov, M. V.\n\n\n \n\n\n\n Polar Biology, 40(11): 2265–2278. November 2017.\n \n\n\n\n
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\n\n\n@article{barrio_background_2017,\n\ttitle = {Background invertebrate herbivory on dwarf birch ({Betula} glandulosa-nana complex) increases with temperature and precipitation across the tundra biome},\n\tvolume = {40},\n\tissn = {1432-2056},\n\turl = {https://doi.org/10.1007/s00300-017-2139-7},\n\tdoi = {10.1007/s00300-017-2139-7},\n\tabstract = {Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2\\% of the leaves and removed 1.4\\% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12\\% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6–7\\% over the current levels with a 1 °C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2024-03-27},\n\tjournal = {Polar Biology},\n\tauthor = {Barrio, Isabel C. and Lindén, Elin and Te Beest, Mariska and Olofsson, Johan and Rocha, Adrian and Soininen, Eeva M. and Alatalo, Juha M. and Andersson, Tommi and Asmus, Ashley and Boike, Julia and Bråthen, Kari Anne and Bryant, John P. and Buchwal, Agata and Bueno, C. Guillermo and Christie, Katherine S. and Denisova, Yulia V. and Egelkraut, Dagmar and Ehrich, Dorothee and Fishback, LeeAnn and Forbes, Bruce C. and Gartzia, Maite and Grogan, Paul and Hallinger, Martin and Heijmans, Monique M. P. D. and Hik, David S. and Hofgaard, Annika and Holmgren, Milena and Høye, Toke T. and Huebner, Diane C. and Jónsdóttir, Ingibjörg Svala and Kaarlejärvi, Elina and Kumpula, Timo and Lange, Cynthia Y. M. J. G. and Lange, Jelena and Lévesque, Esther and Limpens, Juul and Macias-Fauria, Marc and Myers-Smith, Isla and van Nieukerken, Erik J. and Normand, Signe and Post, Eric S. and Schmidt, Niels Martin and Sitters, Judith and Skoracka, Anna and Sokolov, Alexander and Sokolova, Natalya and Speed, James D. M. and Street, Lorna E. and Sundqvist, Maja K. and Suominen, Otso and Tananaev, Nikita and Tremblay, Jean-Pierre and Urbanowicz, Christine and Uvarov, Sergey A. and Watts, David and Wilmking, Martin and Wookey, Philip A. and Zimmermann, Heike H. and Zverev, Vitali and Kozlov, Mikhail V.},\n\tmonth = nov,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Background insect herbivory, Climate change, Externally feeding defoliators, Gall makers, Latitudinal Herbivory Hypothesis, Leaf damage, Leaf miners, Macroecological pattern},\n\tpages = {2265--2278},\n}\n\n\n\n\n\n Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6–7% over the current levels with a 1 °C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Land use influences macroinvertebrate community composition in boreal headwaters through altered stream conditions.\n \n \n \n \n\n\n \n Jonsson, M.; Burrows, R. M.; Lidman, J.; Fältström, E.; Laudon, H.; and Sponseller, R. A.\n\n\n \n\n\n\n Ambio, 46(3): 311–323. April 2017.\n \n\n\n\n
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\n\n\n@article{jonsson_land_2017,\n\ttitle = {Land use influences macroinvertebrate community composition in boreal headwaters through altered stream conditions},\n\tvolume = {46},\n\tissn = {1654-7209},\n\turl = {https://doi.org/10.1007/s13280-016-0837-y},\n\tdoi = {10.1007/s13280-016-0837-y},\n\tabstract = {Land use is known to alter the nature of land–water interactions, but the potential effects of widespread forest management on headwaters in boreal regions remain poorly understood. We evaluated the importance of catchment land use, land cover, and local stream variables for macroinvertebrate community and functional trait diversity in 18 boreal headwater streams. Variation in macroinvertebrate metrics was often best explained by in-stream variables, primarily water chemistry (e.g. pH). However, variation in stream variables was, in turn, significantly associated with catchment-scale forestry land use. More specifically, streams running through catchments that were dominated by young (11–50 years) forests had higher pH, greater organic matter standing stock, higher abundance of aquatic moss, and the highest macroinvertebrate diversity, compared to streams running through recently clear-cut and old forests. This indicates that catchment-scale forest management can modify in-stream habitat conditions with effects on stream macroinvertebrate communities and that characteristics of younger forests may promote conditions that benefit headwater biodiversity.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Ambio},\n\tauthor = {Jonsson, Micael and Burrows, Ryan M. and Lidman, Johan and Fältström, Emma and Laudon, Hjalmar and Sponseller, Ryan A.},\n\tmonth = apr,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Aquatic insects, Biodiversity, Forestry, Functional traits},\n\tpages = {311--323},\n}\n\n\n\n\n\n Land use is known to alter the nature of land–water interactions, but the potential effects of widespread forest management on headwaters in boreal regions remain poorly understood. We evaluated the importance of catchment land use, land cover, and local stream variables for macroinvertebrate community and functional trait diversity in 18 boreal headwater streams. Variation in macroinvertebrate metrics was often best explained by in-stream variables, primarily water chemistry (e.g. pH). However, variation in stream variables was, in turn, significantly associated with catchment-scale forestry land use. More specifically, streams running through catchments that were dominated by young (11–50 years) forests had higher pH, greater organic matter standing stock, higher abundance of aquatic moss, and the highest macroinvertebrate diversity, compared to streams running through recently clear-cut and old forests. This indicates that catchment-scale forest management can modify in-stream habitat conditions with effects on stream macroinvertebrate communities and that characteristics of younger forests may promote conditions that benefit headwater biodiversity.\n
\n\n\n\n \n\n \n \n \n \n \n \n Compositional Stability of the Bacterial Community in a Climate-Sensitive Sub-Arctic Peatland.\n \n \n \n \n\n\n \n Weedon, J. T.; Kowalchuk, G. A.; Aerts, R.; Freriks, S.; Röling, W. F. M.; and van Bodegom, P. M.\n\n\n \n\n\n\n Frontiers in Microbiology, 8: 00317. March 2017.\n Publisher: Frontiers\n\n\n\n
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\n\n\n@article{weedon_compositional_2017,\n\ttitle = {Compositional {Stability} of the {Bacterial} {Community} in a {Climate}-{Sensitive} {Sub}-{Arctic} {Peatland}},\n\tvolume = {8},\n\tissn = {1664-302X},\n\turl = {https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00317/full},\n\tdoi = {10.3389/fmicb.2017.00317},\n\tabstract = {{\\textless}p{\\textgreater}The climate sensitivity of microbe-mediated soil processes such as carbon and nitrogen cycling offers an interesting case for evaluating the corresponding sensitivity of microbial community composition to environmental change. Better understanding of the degree of linkage between functional and compositional stability would contribute to ongoing efforts to build mechanistic models aiming at predicting rates of microbe-mediated processes. We used an amplicon sequencing approach to test if previously observed large effects of experimental soil warming on C and N cycle fluxes (50–100\\% increases) in a sub-arctic {\\textless}italic{\\textgreater}Sphagnum{\\textless}/italic{\\textgreater} peatland were reflected in changes in the composition of the soil bacterial community. We found that treatments that previously induced changes to fluxes did not associate with changes in the phylogenetic composition of the soil bacterial community. For both DNA- and RNA-based analyses, variation in bacterial communities could be explained by the hierarchy: spatial variation (12–15\\% of variance explained) \\> temporal variation (7–11\\%) \\> climate treatment (4–9\\%). We conclude that the bacterial community in this environment is stable under changing conditions, despite the previously observed sensitivity of process rates—evidence that microbe-mediated soil processes can alter without concomitant changes in bacterial communities. We propose that progress in linking soil microbial communities to ecosystem processes can be advanced by further investigating the relative importance of community composition effects versus physico-chemical factors in controlling biogeochemical process rates in different contexts.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\turldate = {2024-03-27},\n\tjournal = {Frontiers in Microbiology},\n\tauthor = {Weedon, James T. and Kowalchuk, George A. and Aerts, Rien and Freriks, Stef and Röling, Wilfred F. M. and van Bodegom, Peter M.},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {Publisher: Frontiers},\n\tkeywords = {\\#nosource, 16S, Bacteria, Carbon, Climate Change, DNA, Nitrogen, Peatlands, RNA, Seasonality},\n\tpages = {00317},\n}\n\n\n\n\n\n \\textlessp\\textgreaterThe climate sensitivity of microbe-mediated soil processes such as carbon and nitrogen cycling offers an interesting case for evaluating the corresponding sensitivity of microbial community composition to environmental change. Better understanding of the degree of linkage between functional and compositional stability would contribute to ongoing efforts to build mechanistic models aiming at predicting rates of microbe-mediated processes. We used an amplicon sequencing approach to test if previously observed large effects of experimental soil warming on C and N cycle fluxes (50–100% increases) in a sub-arctic \\textlessitalic\\textgreaterSphagnum\\textless/italic\\textgreater peatland were reflected in changes in the composition of the soil bacterial community. We found that treatments that previously induced changes to fluxes did not associate with changes in the phylogenetic composition of the soil bacterial community. For both DNA- and RNA-based analyses, variation in bacterial communities could be explained by the hierarchy: spatial variation (12–15% of variance explained) > temporal variation (7–11%) > climate treatment (4–9%). We conclude that the bacterial community in this environment is stable under changing conditions, despite the previously observed sensitivity of process rates—evidence that microbe-mediated soil processes can alter without concomitant changes in bacterial communities. We propose that progress in linking soil microbial communities to ecosystem processes can be advanced by further investigating the relative importance of community composition effects versus physico-chemical factors in controlling biogeochemical process rates in different contexts.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n Both seed germination and seedling mortality increase with experimental warming and fertilization in a subarctic tundra.\n \n \n \n \n\n\n \n Milbau, A.; Vandeplas, N.; Kockelbergh, F.; and Nijs, I.\n\n\n \n\n\n\n AoB PLANTS, 9(5): plx040. September 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{milbau_both_2017,\n\ttitle = {Both seed germination and seedling mortality increase with experimental warming and fertilization in a subarctic tundra},\n\tvolume = {9},\n\tissn = {2041-2851},\n\turl = {https://doi.org/10.1093/aobpla/plx040},\n\tdoi = {10.1093/aobpla/plx040},\n\tabstract = {Climate change is expected to force many species in arctic regions to migrate and track their climatic niche. This requires recruitment from seed, which currently shows very low rates in arctic regions, where long-lived and vegetatively reproducing plants dominate. Therefore, we pose the question whether recruitment (germination and seedling establishment) in arctic regions will significantly improve in a warmer world, and thus allow species to follow their climatic niche. We used a full factorial experiment to examine if realistic warmer temperatures (+3 °C; infrared radiation) and increased nitrogen availability (+1.4 g N m−2 year−1) affected germination, seedling survival and above- and below-ground seedling biomass in five species common in subarctic regions (Anthoxanthum odoratum, Betula nana, Pinus sylvestris, Solidago virgaurea, Vaccinium myrtillus). We found that warming increased seedling emergence in all species, but that subsequent mortality also increased, resulting in no net warming effect on seedling establishment. Warming slightly increased above-ground seedling biomass. Fertilization, on the other hand, did not influence seedling biomass, but it increased seedling establishment in B. nana while it reduced establishment in V. myrtillus. This may help B. nana dominate over V. myrtillus in warmer tundra. Surprisingly, no interactive effects between warming and fertilization were found. The lack of a general positive response of seedling establishment to warmer and more nutrient-rich conditions suggests that (sub)arctic species may experience difficulties in tracking their climatic niche. Predictions of future species distributions in arctic regions solely based on abiotic factors may therefore overestimate species’ ranges due to their poor establishment. Also, the opposite response to fertilization of two key (sub)arctic dwarf shrubs, i.e. B. nana and V. myrtillus, could have important implications for the future development of arctic plant communities and argues for more research into the role of fertilization for plant establishment.},\n\tnumber = {5},\n\turldate = {2024-03-26},\n\tjournal = {AoB PLANTS},\n\tauthor = {Milbau, Ann and Vandeplas, Nicolas and Kockelbergh, Fred and Nijs, Ivan},\n\tmonth = sep,\n\tyear = {2017},\n\tkeywords = {\\#nosource},\n\tpages = {plx040},\n}\n\n\n\n\n\n Climate change is expected to force many species in arctic regions to migrate and track their climatic niche. This requires recruitment from seed, which currently shows very low rates in arctic regions, where long-lived and vegetatively reproducing plants dominate. Therefore, we pose the question whether recruitment (germination and seedling establishment) in arctic regions will significantly improve in a warmer world, and thus allow species to follow their climatic niche. We used a full factorial experiment to examine if realistic warmer temperatures (+3 °C; infrared radiation) and increased nitrogen availability (+1.4 g N m−2 year−1) affected germination, seedling survival and above- and below-ground seedling biomass in five species common in subarctic regions (Anthoxanthum odoratum, Betula nana, Pinus sylvestris, Solidago virgaurea, Vaccinium myrtillus). We found that warming increased seedling emergence in all species, but that subsequent mortality also increased, resulting in no net warming effect on seedling establishment. Warming slightly increased above-ground seedling biomass. Fertilization, on the other hand, did not influence seedling biomass, but it increased seedling establishment in B. nana while it reduced establishment in V. myrtillus. This may help B. nana dominate over V. myrtillus in warmer tundra. Surprisingly, no interactive effects between warming and fertilization were found. The lack of a general positive response of seedling establishment to warmer and more nutrient-rich conditions suggests that (sub)arctic species may experience difficulties in tracking their climatic niche. Predictions of future species distributions in arctic regions solely based on abiotic factors may therefore overestimate species’ ranges due to their poor establishment. Also, the opposite response to fertilization of two key (sub)arctic dwarf shrubs, i.e. B. nana and V. myrtillus, could have important implications for the future development of arctic plant communities and argues for more research into the role of fertilization for plant establishment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Winter ecology of a subalpine grassland: Effects of snow removal on soil respiration, microbial structure and function.\n \n \n \n \n\n\n \n Gavazov, K.; Ingrisch, J.; Hasibeder, R.; Mills, R. T. E.; Buttler, A.; Gleixner, G.; Pumpanen, J.; and Bahn, M.\n\n\n \n\n\n\n Science of The Total Environment, 590-591: 316–324. July 2017.\n \n\n\n\n
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\n\n\n@article{gavazov_winter_2017,\n\ttitle = {Winter ecology of a subalpine grassland: {Effects} of snow removal on soil respiration, microbial structure and function},\n\tvolume = {590-591},\n\tissn = {0048-9697},\n\tshorttitle = {Winter ecology of a subalpine grassland},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969717305156},\n\tdoi = {10.1016/j.scitotenv.2017.03.010},\n\tabstract = {Seasonal snow cover provides essential insulation for mountain ecosystems, but expected changes in precipitation patterns and snow cover duration due to global warming can influence the activity of soil microbial communities. In turn, these changes have the potential to create new dynamics of soil organic matter cycling. To assess the effects of experimental snow removal and advanced spring conditions on soil carbon (C) and nitrogen (N) dynamics, and on the biomass and structure of soil microbial communities, we performed an in situ study in a subalpine grassland in the Austrian Alps, in conjunction with soil incubations under controlled conditions. We found substantial winter C-mineralisation and high accumulation of inorganic and organic N in the topsoil, peaking at snowmelt. Soil microbial biomass doubled under the snow, paralleled by a fivefold increase in its C:N ratio, but no apparent change in its bacteria-dominated community structure. Snow removal led to a series of mild freeze-thaw cycles, which had minor effects on in situ soil CO2 production and N mineralisation. Incubated soil under advanced spring conditions, however, revealed an impaired microbial metabolism shortly after snow removal, characterised by a limited capacity for C-mineralisation of both fresh plant-derived substrates and existing soil organic matter (SOM), leading to reduced priming effects. This effect was transient and the observed recovery in microbial respiration and SOM priming towards the end of the winter season indicated microbial resilience to short-lived freeze-thaw disturbance under field conditions. Bacteria showed a higher potential for uptake of plant-derived C substrates during this recovery phase. The observed temporary loss in microbial C-mineralisation capacity and the promotion of bacteria over fungi can likely impede winter SOM cycling in mountain grasslands under recurrent winter climate change events, with plausible implications for soil nutrient availability and plant-soil interactions.},\n\turldate = {2024-03-26},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Gavazov, Konstantin and Ingrisch, Johannes and Hasibeder, Roland and Mills, Robert T. E. and Buttler, Alexandre and Gleixner, Gerd and Pumpanen, Jukka and Bahn, Michael},\n\tmonth = jul,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Climate change, Fungal:Bacterial ratio, Microbial C:N, PLFA, Priming effect, Substrate induced respiration, climate change, plfa},\n\tpages = {316--324},\n}\n\n\n\n\n\n Seasonal snow cover provides essential insulation for mountain ecosystems, but expected changes in precipitation patterns and snow cover duration due to global warming can influence the activity of soil microbial communities. In turn, these changes have the potential to create new dynamics of soil organic matter cycling. To assess the effects of experimental snow removal and advanced spring conditions on soil carbon (C) and nitrogen (N) dynamics, and on the biomass and structure of soil microbial communities, we performed an in situ study in a subalpine grassland in the Austrian Alps, in conjunction with soil incubations under controlled conditions. We found substantial winter C-mineralisation and high accumulation of inorganic and organic N in the topsoil, peaking at snowmelt. Soil microbial biomass doubled under the snow, paralleled by a fivefold increase in its C:N ratio, but no apparent change in its bacteria-dominated community structure. Snow removal led to a series of mild freeze-thaw cycles, which had minor effects on in situ soil CO2 production and N mineralisation. Incubated soil under advanced spring conditions, however, revealed an impaired microbial metabolism shortly after snow removal, characterised by a limited capacity for C-mineralisation of both fresh plant-derived substrates and existing soil organic matter (SOM), leading to reduced priming effects. This effect was transient and the observed recovery in microbial respiration and SOM priming towards the end of the winter season indicated microbial resilience to short-lived freeze-thaw disturbance under field conditions. Bacteria showed a higher potential for uptake of plant-derived C substrates during this recovery phase. The observed temporary loss in microbial C-mineralisation capacity and the promotion of bacteria over fungi can likely impede winter SOM cycling in mountain grasslands under recurrent winter climate change events, with plausible implications for soil nutrient availability and plant-soil interactions.\n
\n\n\n\n \n\n \n \n \n \n \n \n An Operational Framework for the Advancement of a Molecule-to-Biosphere Stoichiometry Theory.\n \n \n \n \n\n\n \n Cherif, M.; Faithfull, C.; Guo, J.; Meunier, C. L.; Sitters, J.; Uszko, W.; and Rivera Vasconcelos, F.\n\n\n \n\n\n\n Frontiers in Marine Science, 4: 00286. 2017.\n 00000\n\n\n\n
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\n\n\n@article{cherif_operational_2017,\n\ttitle = {An {Operational} {Framework} for the {Advancement} of a {Molecule}-to-{Biosphere} {Stoichiometry} {Theory}},\n\tvolume = {4},\n\tissn = {2296-7745},\n\turl = {http://journal.frontiersin.org/article/10.3389/fmars.2017.00286/full},\n\tdoi = {10.3389/fmars.2017.00286},\n\tabstract = {Biological stoichiometry is an approach that focuses on the balance of elements in biological interactions. It is a theory that has the potential to causally link material processes at all biological levels – from molecules to the biosphere. But the lack of a coherent operational framework has so far restricted progress in this direction. Here, we provide a framework to help infer how a stoichiometric imbalance observed at one level impacts all other biological levels. Our framework enables us to high the areas of the theory in need of completion, development and integration at all biological levels. Our hope is that this framework will contribute to the building of a more predictive theory of elemental transfers within the biosphere, and thus, to a better understanding of human-induced perturbations to the global biogeochemical cycles.},\n\tlanguage = {English},\n\turldate = {2017-09-11},\n\tjournal = {Frontiers in Marine Science},\n\tauthor = {Cherif, Mehdi and Faithfull, Carolyn and Guo, Junwen and Meunier, Cédric L. and Sitters, Judith and Uszko, Wojciech and Rivera Vasconcelos, Francisco},\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Biological stoichiometry, Consumer-driven nutrient recycling, Growth-rate hypothesis, Ligh:nutrient hypothesis, biological organization, ecological theory, theory integration},\n\tpages = {00286},\n}\n\n\n\n\n\n Biological stoichiometry is an approach that focuses on the balance of elements in biological interactions. It is a theory that has the potential to causally link material processes at all biological levels – from molecules to the biosphere. But the lack of a coherent operational framework has so far restricted progress in this direction. Here, we provide a framework to help infer how a stoichiometric imbalance observed at one level impacts all other biological levels. Our framework enables us to high the areas of the theory in need of completion, development and integration at all biological levels. Our hope is that this framework will contribute to the building of a more predictive theory of elemental transfers within the biosphere, and thus, to a better understanding of human-induced perturbations to the global biogeochemical cycles.\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-lasting ecological legacies of reindeer on tundra vegetation.\n \n \n \n \n\n\n \n Egelkraut, D. D.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2017.\n Publisher: Umeå University\n\n\n\n
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\n\n\n@phdthesis{egelkraut_long-lasting_2017,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Long-lasting ecological legacies of reindeer on tundra vegetation},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-142131},\n\tabstract = {Reindeer can have strong effects on the plant species composition and functioning of tundra ecosystems, and often promote a transition towards a graminoid-dominated vegetation type. As a result, th ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Egelkraut, Dagmar D.},\n\tcollaborator = {Olofsson, Johan and Forbes, Bruce C. and Tømmervik, Hans},\n\tyear = {2017},\n\tnote = {Publisher: Umeå University},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n Reindeer can have strong effects on the plant species composition and functioning of tundra ecosystems, and often promote a transition towards a graminoid-dominated vegetation type. As a result, th ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Sensitivity of soil carbon fractions and their specific stabilization mechanisms to extreme soil warming in a subarctic grassland.\n \n \n \n \n\n\n \n Poeplau, C.; Kätterer, T.; Leblans, N. I. W.; and Sigurdsson, B. D.\n\n\n \n\n\n\n Global Change Biology, 23(3): 1316–1327. 2017.\n \n\n\n\n
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\n\n\n@article{poeplau_sensitivity_2017,\n\ttitle = {Sensitivity of soil carbon fractions and their specific stabilization mechanisms to extreme soil warming in a subarctic grassland},\n\tvolume = {23},\n\tcopyright = {© 2016 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13491},\n\tdoi = {10.1111/gcb.13491},\n\tabstract = {Terrestrial carbon cycle feedbacks to global warming are major uncertainties in climate models. For in-depth understanding of changes in soil organic carbon (SOC) after soil warming, long-term responses of SOC stabilization mechanisms such as aggregation, organo-mineral interactions and chemical recalcitrance need to be addressed. This study investigated the effect of 6 years of geothermal soil warming on different SOC fractions in an unmanaged grassland in Iceland. Along an extreme warming gradient of +0 to +40 °C, we isolated five fractions of SOC that varied conceptually in turnover rate from active to passive in the following order: particulate organic matter (POM), dissolved organic carbon (DOC), SOC in sand and stable aggregates (SA), SOC in silt and clay (SC-rSOC) and resistant SOC (rSOC). Soil warming of 0.6 °C increased bulk SOC by 22 ± 43\\% (0–10 cm soil layer) and 27 ± 54\\% (20–30 cm), while further warming led to exponential SOC depletion of up to 79 ± 14\\% (0–10 cm) and 74 ± 8\\% (20–30) in the most warmed plots ( +40 °C). Only the SA fraction was more sensitive than the bulk soil, with 93 ± 6\\% (0–10 cm) and 86 ± 13\\% (20–30 cm) SOC losses and the highest relative enrichment in 13C as an indicator for the degree of decomposition (+1.6 ± 1.5‰ in 0–10 cm and +1.3 ± 0.8‰ in 20–30 cm). The SA fraction mass also declined along the warming gradient, while the SC fraction mass increased. This was explained by deactivation of aggregate-binding mechanisms. There was no difference between the responses of SC-rSOC (slow-cycling) and rSOC (passive) to warming, and 13C enrichment in rSOC was equal to that in bulk soil. We concluded that the sensitivity of SOC to warming was not a function of age or chemical recalcitrance, but triggered by changes in biophysical stabilization mechanisms, such as aggregation.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2019-05-20},\n\tjournal = {Global Change Biology},\n\tauthor = {Poeplau, Christopher and Kätterer, Thomas and Leblans, Niki I. W. and Sigurdsson, Bjarni D.},\n\tyear = {2017},\n\tkeywords = {\\#nosource, global change, soil carbon fractionation, soil organic matter, soil warming, temperature manipulation, temperature sensitivity, trophic fractionation, δ13C},\n\tpages = {1316--1327},\n}\n\n\n\n\n\n Terrestrial carbon cycle feedbacks to global warming are major uncertainties in climate models. For in-depth understanding of changes in soil organic carbon (SOC) after soil warming, long-term responses of SOC stabilization mechanisms such as aggregation, organo-mineral interactions and chemical recalcitrance need to be addressed. This study investigated the effect of 6 years of geothermal soil warming on different SOC fractions in an unmanaged grassland in Iceland. Along an extreme warming gradient of +0 to +40 °C, we isolated five fractions of SOC that varied conceptually in turnover rate from active to passive in the following order: particulate organic matter (POM), dissolved organic carbon (DOC), SOC in sand and stable aggregates (SA), SOC in silt and clay (SC-rSOC) and resistant SOC (rSOC). Soil warming of 0.6 °C increased bulk SOC by 22 ± 43% (0–10 cm soil layer) and 27 ± 54% (20–30 cm), while further warming led to exponential SOC depletion of up to 79 ± 14% (0–10 cm) and 74 ± 8% (20–30) in the most warmed plots ( +40 °C). Only the SA fraction was more sensitive than the bulk soil, with 93 ± 6% (0–10 cm) and 86 ± 13% (20–30 cm) SOC losses and the highest relative enrichment in 13C as an indicator for the degree of decomposition (+1.6 ± 1.5‰ in 0–10 cm and +1.3 ± 0.8‰ in 20–30 cm). The SA fraction mass also declined along the warming gradient, while the SC fraction mass increased. This was explained by deactivation of aggregate-binding mechanisms. There was no difference between the responses of SC-rSOC (slow-cycling) and rSOC (passive) to warming, and 13C enrichment in rSOC was equal to that in bulk soil. We concluded that the sensitivity of SOC to warming was not a function of age or chemical recalcitrance, but triggered by changes in biophysical stabilization mechanisms, such as aggregation.\n
\n\n\n\n \n\n \n \n \n \n \n \n The emissions of nitrous oxide and methane from natural soil temperature gradients in a volcanic area in southwest Iceland.\n \n \n \n \n\n\n \n Maljanen, M.; Yli-Moijala, H.; Biasi, C.; Leblans, N. I. W.; De Boeck, H. J.; Bjarnadóttir, B.; and Sigurdsson, B. D.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 109: 70–80. June 2017.\n \n\n\n\n
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\n\n\n@article{maljanen_emissions_2017,\n\ttitle = {The emissions of nitrous oxide and methane from natural soil temperature gradients in a volcanic area in southwest {Iceland}},\n\tvolume = {109},\n\tissn = {0038-0717},\n\turl = {http://www.sciencedirect.com/science/article/pii/S003807171730130X},\n\tdoi = {10.1016/j.soilbio.2017.01.021},\n\tabstract = {Nitrous oxide (N2O) and methane (CH4) emissions were measured along three natural geothermal soil temperature (Ts) gradients in freely drained upland soils in a volcanic area in Iceland. Two of the Ts gradients (underneath a grassland (GN) and a forest site (FN), respectively) were recently formed (in May 2008) and thus subjected to relatively short-term warming. The third Ts gradient, underneath another grassland site (GO), had been subjected to long-term soil warming (over at least 45 years). The N2O and CH4 emissions were measured using the static chamber method. In addition, subsurface soil gas concentrations (5–20 cm) were studied. N2O emissions from GN were slightly higher than those from GO in the temperature elevation range up to +5 °C, while CH4 uptake rates were similar. Under moderate soil warming ({\\textless}+5 °C) there were no significant increases in gas flux rates within any of the sites, but when soil warming exceeded +20 °C, both N2O and CH4 emissions increased significantly at all sites. While net uptake of CH4 (up to −0.15 mg CH4 m−2 h−1) and occasional N2O uptake (up to −12 μg N2O m−2 h−1) were measured in the unwarmed plots at all sites, net emissions were only measured from the warmest plots (up to 2600 μg N2O m−2 h−1 and up to 1.3 mg CH4 m−2 h−1). The subsurface soil N2O concentrations increased with soil warming, indicating enhanced N-turnover. Subsurface soil CH4 concentrations initially decreased under moderate soil warming (up to +5 °C), but above that threshold they also increased significantly. A portion of the N2O and CH4 emitted from the warmest plots may, however, be geothermally derived, this should be further confirmed with isotope studies. In conclusion, our research suggests that moderate increases in soil temperature (up to +5 °C) may not significantly increase N2O and CH4 emissions at these upland soils, both in the short and longer term. However, warming trends exceeding +5 °C as predicted for 2100 in pessimistic scenarios may cause increased trace gas emissions and thus significant positive feedbacks to climate change.},\n\turldate = {2019-05-20},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Maljanen, Marja and Yli-Moijala, Heli and Biasi, Christina and Leblans, Niki I. W. and De Boeck, Hans J. and Bjarnadóttir, Brynhildur and Sigurdsson, Bjarni D.},\n\tmonth = jun,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Andosol, Carbon, Geothermal, Greenhouse gas, Nitrogen, Warming},\n\tpages = {70--80},\n}\n\n\n\n\n\n Nitrous oxide (N2O) and methane (CH4) emissions were measured along three natural geothermal soil temperature (Ts) gradients in freely drained upland soils in a volcanic area in Iceland. Two of the Ts gradients (underneath a grassland (GN) and a forest site (FN), respectively) were recently formed (in May 2008) and thus subjected to relatively short-term warming. The third Ts gradient, underneath another grassland site (GO), had been subjected to long-term soil warming (over at least 45 years). The N2O and CH4 emissions were measured using the static chamber method. In addition, subsurface soil gas concentrations (5–20 cm) were studied. N2O emissions from GN were slightly higher than those from GO in the temperature elevation range up to +5 °C, while CH4 uptake rates were similar. Under moderate soil warming (\\textless+5 °C) there were no significant increases in gas flux rates within any of the sites, but when soil warming exceeded +20 °C, both N2O and CH4 emissions increased significantly at all sites. While net uptake of CH4 (up to −0.15 mg CH4 m−2 h−1) and occasional N2O uptake (up to −12 μg N2O m−2 h−1) were measured in the unwarmed plots at all sites, net emissions were only measured from the warmest plots (up to 2600 μg N2O m−2 h−1 and up to 1.3 mg CH4 m−2 h−1). The subsurface soil N2O concentrations increased with soil warming, indicating enhanced N-turnover. Subsurface soil CH4 concentrations initially decreased under moderate soil warming (up to +5 °C), but above that threshold they also increased significantly. A portion of the N2O and CH4 emitted from the warmest plots may, however, be geothermally derived, this should be further confirmed with isotope studies. In conclusion, our research suggests that moderate increases in soil temperature (up to +5 °C) may not significantly increase N2O and CH4 emissions at these upland soils, both in the short and longer term. However, warming trends exceeding +5 °C as predicted for 2100 in pessimistic scenarios may cause increased trace gas emissions and thus significant positive feedbacks to climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Phenological responses of Icelandic subarctic grasslands to short-term and long-term natural soil warming.\n \n \n \n \n\n\n \n Leblans, N. I. W.; Sigurdsson, B. D.; Vicca, S.; Fu, Y.; Penuelas, J.; and Janssens, I. A.\n\n\n \n\n\n\n Global Change Biology, 23(11): 4932–4945. 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{leblans_phenological_2017,\n\ttitle = {Phenological responses of {Icelandic} subarctic grasslands to short-term and long-term natural soil warming},\n\tvolume = {23},\n\tcopyright = {© 2017 John Wiley \\& Sons Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13749},\n\tdoi = {10.1111/gcb.13749},\n\tabstract = {The phenology of vegetation, particularly the length of the growing season (LOS; i.e., the period from greenup to senescence), is highly sensitive to climate change, which could imply potent feedbacks to the climate system, for example, by altering the ecosystem carbon (C) balance. In recent decades, the largest extensions of LOS have been reported at high northern latitudes, but further warming-induced LOS extensions may be constrained by too short photoperiod or unfulfilled chilling requirements. Here, we studied subarctic grasslands, which cover a vast area and contain large C stocks, but for which LOS changes under further warming are highly uncertain. We measured LOS extensions of Icelandic subarctic grasslands along natural geothermal soil warming gradients of different age (short term, where the measurements started after 5 years of warming and long term, i.e., warmed since ≥50 years) using ground-level measurements of normalized difference vegetation index. We found that LOS linearly extended with on average 2.1 days per °C soil warming up to the highest soil warming levels (ca. +10°C) and that LOS had the potential to extend at least 1 month. This indicates that the warming impact on LOS in these subarctic grasslands will likely not saturate in the near future. A similar response to short- and long-term warming indicated a strong physiological control of the phenological response of the subarctic grasslands to warming and suggested that genetic adaptations and community changes were likely of minor importance. We conclude that the warming-driven extension of the LOSs of these subarctic grasslands did not saturate up to +10°C warming, and hence that growing seasons of high-latitude grasslands are likely to continue lengthening with future warming (unless genetic adaptations or species shifts do occur). This persistence of the warming-induced extension of LOS has important implications for the C-sink potential of subarctic grasslands under climate change.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2019-05-20},\n\tjournal = {Global Change Biology},\n\tauthor = {Leblans, Niki I. W. and Sigurdsson, Bjarni D. and Vicca, Sara and Fu, Yongshuo and Penuelas, Josep and Janssens, Ivan A.},\n\tyear = {2017},\n\tkeywords = {\\#nosource, Iceland, climate change, geothermal warming, normalized difference vegetation index, phenology, subarctic grassland},\n\tpages = {4932--4945},\n}\n\n\n\n\n\n The phenology of vegetation, particularly the length of the growing season (LOS; i.e., the period from greenup to senescence), is highly sensitive to climate change, which could imply potent feedbacks to the climate system, for example, by altering the ecosystem carbon (C) balance. In recent decades, the largest extensions of LOS have been reported at high northern latitudes, but further warming-induced LOS extensions may be constrained by too short photoperiod or unfulfilled chilling requirements. Here, we studied subarctic grasslands, which cover a vast area and contain large C stocks, but for which LOS changes under further warming are highly uncertain. We measured LOS extensions of Icelandic subarctic grasslands along natural geothermal soil warming gradients of different age (short term, where the measurements started after 5 years of warming and long term, i.e., warmed since ≥50 years) using ground-level measurements of normalized difference vegetation index. We found that LOS linearly extended with on average 2.1 days per °C soil warming up to the highest soil warming levels (ca. +10°C) and that LOS had the potential to extend at least 1 month. This indicates that the warming impact on LOS in these subarctic grasslands will likely not saturate in the near future. A similar response to short- and long-term warming indicated a strong physiological control of the phenological response of the subarctic grasslands to warming and suggested that genetic adaptations and community changes were likely of minor importance. We conclude that the warming-driven extension of the LOSs of these subarctic grasslands did not saturate up to +10°C warming, and hence that growing seasons of high-latitude grasslands are likely to continue lengthening with future warming (unless genetic adaptations or species shifts do occur). This persistence of the warming-induced extension of LOS has important implications for the C-sink potential of subarctic grasslands under climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Icelandic grasslands as long-term C sinks under elevated organic N inputs.\n \n \n \n \n\n\n \n Leblans, N. I. W.; Sigurdsson, B. D.; Aerts, R.; Vicca, S.; Magnússon, B.; and Janssens, I. A.\n\n\n \n\n\n\n Biogeochemistry, 134(3): 279–299. August 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{leblans_icelandic_2017,\n\ttitle = {Icelandic grasslands as long-term {C} sinks under elevated organic {N} inputs},\n\tvolume = {134},\n\tissn = {1573-515X},\n\turl = {https://doi.org/10.1007/s10533-017-0362-5},\n\tdoi = {10.1007/s10533-017-0362-5},\n\tabstract = {About 10\\% of the anthropogenic CO2 emissions have been absorbed by northern terrestrial ecosystems during the past decades. It has been hypothesized that part of this increasing carbon (C) sink is caused by the alleviation of nitrogen (N) limitation by increasing anthropogenic N inputs. However, little is known about this N-dependent C sink. Here, we studied the effect of chronic seabird-derived N inputs (47–67 kg N ha−1 year−1) on the net soil organic C (SOC) storage rate of unmanaged Icelandic grasslands on the volcanic Vestmannaeyjar archipelago by using a stock change approach in combination with soil dating. We studied both early developmental (young) soils that had been receiving increased N inputs over a decadal timescale since an eruption in 1963, and well-developed soils, that had been receiving N inputs over a millennial timescale. For the latter, however, the effects on both decadal (topsoil; 40 years) and millennial (total soil profile; 1600 years) SOC storage could be studied, as the age of topsoil and the total soil profile could be determined from volcanic ash layers deposited in 1973 and 395 AD. We found that enhanced N availability—either from accumulation over time, or seabird derived—increased the net SOC storage rate. Under low N inputs, early developmental soils were weak decadal C sinks (0.018 ton SOC ha−1 year−1), but this increased quickly under ca. 30 years of elevated N inputs to 0.29 ton SOC ha−1 year−1, thereby equalling the decadal SOC storage rate of the unfertilized well-developed soils. Furthermore, for the well-developed soils, chronically elevated N inputs not only stimulated the decadal SOC storage rate in the topsoil, but also the total millennial SOC storage was consistently higher. Hence, our study suggests that Icelandic grasslands, if not disturbed, can remain C sinks for many centuries under current climatic conditions and that chronically elevated N inputs can induce a permanent strengthening of this sink.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2019-05-20},\n\tjournal = {Biogeochemistry},\n\tauthor = {Leblans, Niki I. W. and Sigurdsson, Bjarni D. and Aerts, Rien and Vicca, Sara and Magnússon, Borgthór and Janssens, Ivan A.},\n\tmonth = aug,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Long-term carbon storage, N inputs, Soil development, Surtsey, Terrestrial C sink},\n\tpages = {279--299},\n}\n\n\n\n\n\n About 10% of the anthropogenic CO2 emissions have been absorbed by northern terrestrial ecosystems during the past decades. It has been hypothesized that part of this increasing carbon (C) sink is caused by the alleviation of nitrogen (N) limitation by increasing anthropogenic N inputs. However, little is known about this N-dependent C sink. Here, we studied the effect of chronic seabird-derived N inputs (47–67 kg N ha−1 year−1) on the net soil organic C (SOC) storage rate of unmanaged Icelandic grasslands on the volcanic Vestmannaeyjar archipelago by using a stock change approach in combination with soil dating. We studied both early developmental (young) soils that had been receiving increased N inputs over a decadal timescale since an eruption in 1963, and well-developed soils, that had been receiving N inputs over a millennial timescale. For the latter, however, the effects on both decadal (topsoil; 40 years) and millennial (total soil profile; 1600 years) SOC storage could be studied, as the age of topsoil and the total soil profile could be determined from volcanic ash layers deposited in 1973 and 395 AD. We found that enhanced N availability—either from accumulation over time, or seabird derived—increased the net SOC storage rate. Under low N inputs, early developmental soils were weak decadal C sinks (0.018 ton SOC ha−1 year−1), but this increased quickly under ca. 30 years of elevated N inputs to 0.29 ton SOC ha−1 year−1, thereby equalling the decadal SOC storage rate of the unfertilized well-developed soils. Furthermore, for the well-developed soils, chronically elevated N inputs not only stimulated the decadal SOC storage rate in the topsoil, but also the total millennial SOC storage was consistently higher. Hence, our study suggests that Icelandic grasslands, if not disturbed, can remain C sinks for many centuries under current climatic conditions and that chronically elevated N inputs can induce a permanent strengthening of this sink.\n
\n\n\n\n \n\n \n \n \n \n \n \n Impact of Soil Warming on the Plant Metabolome of Icelandic Grasslands.\n \n \n \n \n\n\n \n Gargallo-Garriga, A.; Ayala-Roque, M.; Sardans, J.; Bartrons, M.; Granda, V.; Sigurdsson, B. D.; Leblans, N. I. W.; Oravec, M.; Urban, O.; Janssens, I. A.; and Peñuelas, J.\n\n\n \n\n\n\n Metabolites, 7(3): 44. September 2017.\n \n\n\n\n
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\n\n\n@article{gargallo-garriga_impact_2017,\n\ttitle = {Impact of {Soil} {Warming} on the {Plant} {Metabolome} of {Icelandic} {Grasslands}},\n\tvolume = {7},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\turl = {https://www.mdpi.com/2218-1989/7/3/44},\n\tdoi = {10.3390/metabo7030044},\n\tabstract = {Climate change is stronger at high than at temperate and tropical latitudes. The natural geothermal conditions in southern Iceland provide an opportunity to study the impact of warming on plants, because of the geothermal bedrock channels that induce stable gradients of soil temperature. We studied two valleys, one where such gradients have been present for centuries (long-term treatment), and another where new gradients were created in 2008 after a shallow crustal earthquake (short-term treatment). We studied the impact of soil warming (0 to +15 °C) on the foliar metabolomes of two common plant species of high northern latitudes: Agrostis capillaris, a monocotyledon grass; and Ranunculus acris, a dicotyledonous herb, and evaluated the dependence of shifts in their metabolomes on the length of the warming treatment. The two species responded differently to warming, depending on the length of exposure. The grass metabolome clearly shifted at the site of long-term warming, but the herb metabolome did not. The main up-regulated compounds at the highest temperatures at the long-term site were saccharides and amino acids, both involved in heat-shock metabolic pathways. Moreover, some secondary metabolites, such as phenolic acids and terpenes, associated with a wide array of stresses, were also up-regulated. Most current climatic models predict an increase in annual average temperature between 2–8 °C over land masses in the Arctic towards the end of this century. The metabolomes of A. capillaris and R. acris shifted abruptly and nonlinearly to soil warming \\>5 °C above the control temperature for the coming decades. These results thus suggest that a slight warming increase may not imply substantial changes in plant function, but if the temperature rises more than 5 °C, warming may end up triggering metabolic pathways associated with heat stress in some plant species currently dominant in this region.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2019-05-20},\n\tjournal = {Metabolites},\n\tauthor = {Gargallo-Garriga, Albert and Ayala-Roque, Marta and Sardans, Jordi and Bartrons, Mireia and Granda, Victor and Sigurdsson, Bjarni D. and Leblans, Niki I. W. and Oravec, Michal and Urban, Otmar and Janssens, Ivan A. and Peñuelas, Josep},\n\tmonth = sep,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Iceland, climate change, geothermal bedrock channels, grassland, metabolome, warming},\n\tpages = {44},\n}\n\n\n\n\n\n Climate change is stronger at high than at temperate and tropical latitudes. The natural geothermal conditions in southern Iceland provide an opportunity to study the impact of warming on plants, because of the geothermal bedrock channels that induce stable gradients of soil temperature. We studied two valleys, one where such gradients have been present for centuries (long-term treatment), and another where new gradients were created in 2008 after a shallow crustal earthquake (short-term treatment). We studied the impact of soil warming (0 to +15 °C) on the foliar metabolomes of two common plant species of high northern latitudes: Agrostis capillaris, a monocotyledon grass; and Ranunculus acris, a dicotyledonous herb, and evaluated the dependence of shifts in their metabolomes on the length of the warming treatment. The two species responded differently to warming, depending on the length of exposure. The grass metabolome clearly shifted at the site of long-term warming, but the herb metabolome did not. The main up-regulated compounds at the highest temperatures at the long-term site were saccharides and amino acids, both involved in heat-shock metabolic pathways. Moreover, some secondary metabolites, such as phenolic acids and terpenes, associated with a wide array of stresses, were also up-regulated. Most current climatic models predict an increase in annual average temperature between 2–8 °C over land masses in the Arctic towards the end of this century. The metabolomes of A. capillaris and R. acris shifted abruptly and nonlinearly to soil warming >5 °C above the control temperature for the coming decades. These results thus suggest that a slight warming increase may not imply substantial changes in plant function, but if the temperature rises more than 5 °C, warming may end up triggering metabolic pathways associated with heat stress in some plant species currently dominant in this region.\n
\n\n\n\n \n\n \n \n \n \n \n \n Mosses as mediators of climate change: implications for tree seedling establishment in the tundra.\n \n \n \n \n\n\n \n Lett, S.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2017.\n 00000\n\n\n\n
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\n\n\n@phdthesis{lett_mosses_2017,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Mosses as mediators of climate change: implications for tree seedling establishment in the tundra},\n\turl = {http://www.diva-portal.org/smash/record.jsf?pid=diva2%3A1070385&dswid=3684},\n\tabstract = {Alpine and arctic tree line expansion depends on the establishment of tree seedlings above the current tree line, which is expected to occur with climate warming. However, tree lines often fail to respond to higher temperatures. Other environmental factors are therefore likely important for tree seedling establishment. Above the tree line, establishing seedlings encounter existing vegetation such as bryophytes, which often dominate in arctic and alpine tundra. Bryophytes modify their environment in various ways and may mediate climate change effects on establishing tree seedlings, and with that tree line expansion. The aim of this thesis was to understand if and how the environment, in particular bryophytes, mediates the impact of climate change on tree seedling establishment at the alpine and arctic tree line. This was explored by reviewing literature on tree seedling establishment at alpine and arctic tree lines globally. In addition, tree seedling survival and growth of Betula pubescens and Pinus sylvestris were assessed experimentally. Here, individuals were planted into mono-specific mats of different bryophytes species and exposed to warming and different precipitation regimes. The literature review revealed that besides from temperature, tree seedling establishment is affected by a wide range of abiotic and biotic factors including water, snow, nutrients, light, disturbance and surrounding vegetation. Furthermore the review revealed that for example vegetation can change tree seedling responses to climate change. The experiments showed that especially tree seedling survival was adversely affected by the presence of bryophytes and that the impacts of bryophytes were larger than those of the climate treatments. Seedling growth, on the other hand, was not hampered by the presence of bryophytes, which is in line with earlier findings that seedling survival, growth and seed germination do not respond similarly to changes in environmental conditions. Moreover, we found several indications that vegetation above the tree line, including bryophytes, mediated tree seedling responses to warming and precipitation or snow cover. This thesis shows that temperature alone should not be used to predict future tree seedling establishment above the alpine and arctic tree line and that extrapolations from climate envelope models could strongly over or under estimate tree line responses to warming. This underlines the value of multi-factorial studies for understanding the interplay between warming and other environmental factors and their effects on tree seedling establishment across current tree lines.},\n\tlanguage = {eng},\n\turldate = {2017-02-28},\n\tschool = {Umeå University},\n\tauthor = {Lett, Signe},\n\tcollaborator = {Dorrepaal, Ellen and Wardle, David A. and Nilsson, Marie-Charlotte},\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Alpine and arctic tree line expansion depends on the establishment of tree seedlings above the current tree line, which is expected to occur with climate warming. However, tree lines often fail to respond to higher temperatures. Other environmental factors are therefore likely important for tree seedling establishment. Above the tree line, establishing seedlings encounter existing vegetation such as bryophytes, which often dominate in arctic and alpine tundra. Bryophytes modify their environment in various ways and may mediate climate change effects on establishing tree seedlings, and with that tree line expansion. The aim of this thesis was to understand if and how the environment, in particular bryophytes, mediates the impact of climate change on tree seedling establishment at the alpine and arctic tree line. This was explored by reviewing literature on tree seedling establishment at alpine and arctic tree lines globally. In addition, tree seedling survival and growth of Betula pubescens and Pinus sylvestris were assessed experimentally. Here, individuals were planted into mono-specific mats of different bryophytes species and exposed to warming and different precipitation regimes. The literature review revealed that besides from temperature, tree seedling establishment is affected by a wide range of abiotic and biotic factors including water, snow, nutrients, light, disturbance and surrounding vegetation. Furthermore the review revealed that for example vegetation can change tree seedling responses to climate change. The experiments showed that especially tree seedling survival was adversely affected by the presence of bryophytes and that the impacts of bryophytes were larger than those of the climate treatments. Seedling growth, on the other hand, was not hampered by the presence of bryophytes, which is in line with earlier findings that seedling survival, growth and seed germination do not respond similarly to changes in environmental conditions. Moreover, we found several indications that vegetation above the tree line, including bryophytes, mediated tree seedling responses to warming and precipitation or snow cover. This thesis shows that temperature alone should not be used to predict future tree seedling establishment above the alpine and arctic tree line and that extrapolations from climate envelope models could strongly over or under estimate tree line responses to warming. This underlines the value of multi-factorial studies for understanding the interplay between warming and other environmental factors and their effects on tree seedling establishment across current tree lines.\n
\n\n\n\n \n\n \n \n \n \n \n \n Legacy effects of altered flooding regimes on decomposition in a boreal floodplain.\n \n \n \n \n\n\n \n Sarneel, J. M. J.; and Veen, G. F. C.\n\n\n \n\n\n\n Plant and Soil, 421(1): 57–66. December 2017.\n \n\n\n\n
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\n\n\n@article{sarneel_legacy_2017,\n\ttitle = {Legacy effects of altered flooding regimes on decomposition in a boreal floodplain},\n\tvolume = {421},\n\tissn = {1573-5036},\n\turl = {https://doi.org/10.1007/s11104-017-3382-y},\n\tdoi = {10.1007/s11104-017-3382-y},\n\tabstract = {Background and aimsSince long-term experiments are scarce, we have poor understanding of how changed flooding regimes affect processes such as litter decomposition.MethodsWe simulated short- and long-term changed flooding regimes by transplanting turfs between low (frequently flooded) and high (in-frequently flooded) elevations on the river bank in 2000 (old turfs) and 2014 (young turfs). We tested how incubation elevation, turf origin and turf age affected decomposition of standard litter (tea) and four types of local litter.ResultsFor tea, we found that the initial decomposition rate (k) and stabilization (S) of labile material during the second decomposition phase were highest at high incubation elevation. We found intermediate values for k and S in young transplanted turfs, but turf origin was not important in old turfs. Local litter mass loss was generally highest at high incubation elevations, and effects of turf origin and turf age were litter-specific.ConclusionWe conclude that incubation elevation, i.e., the current flooding regime, was the most important factor driving decomposition. Soil origin (flooding history) affected decomposition of tea only in young turfs. Therefore, we expect that changes in flooding regimes predominantly affect decomposition directly, while indirect legacy effects are weaker and litter- or site-specific.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2019-03-27},\n\tjournal = {Plant and Soil},\n\tauthor = {Sarneel, J. M. Judith and Veen, G. F. Ciska},\n\tmonth = dec,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Boreal zone, Ecosystem function, Floodplain, River management, TBI, Tea bag method},\n\tpages = {57--66},\n}\n\n\n\n\n\n Background and aimsSince long-term experiments are scarce, we have poor understanding of how changed flooding regimes affect processes such as litter decomposition.MethodsWe simulated short- and long-term changed flooding regimes by transplanting turfs between low (frequently flooded) and high (in-frequently flooded) elevations on the river bank in 2000 (old turfs) and 2014 (young turfs). We tested how incubation elevation, turf origin and turf age affected decomposition of standard litter (tea) and four types of local litter.ResultsFor tea, we found that the initial decomposition rate (k) and stabilization (S) of labile material during the second decomposition phase were highest at high incubation elevation. We found intermediate values for k and S in young transplanted turfs, but turf origin was not important in old turfs. Local litter mass loss was generally highest at high incubation elevations, and effects of turf origin and turf age were litter-specific.ConclusionWe conclude that incubation elevation, i.e., the current flooding regime, was the most important factor driving decomposition. Soil origin (flooding history) affected decomposition of tea only in young turfs. Therefore, we expect that changes in flooding regimes predominantly affect decomposition directly, while indirect legacy effects are weaker and litter- or site-specific.\n
\n\n\n\n \n\n \n \n \n \n \n \n The volume and mean depth of Earth's lakes.\n \n \n \n \n\n\n \n Cael, B. B.; Heathcote, A. J.; and Seekell, D. A.\n\n\n \n\n\n\n Geophysical Research Letters, 44(1): 2016GL071378. January 2017.\n 00003\n\n\n\n
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\n\n\n@article{cael_volume_2017,\n\ttitle = {The volume and mean depth of {Earth}'s lakes},\n\tvolume = {44},\n\tissn = {1944-8007},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/2016GL071378/abstract},\n\tdoi = {10.1002/2016GL071378},\n\tabstract = {Global lake volume estimates are scarce, highly variable, and poorly documented. We developed a rigorous method for estimating global lake depth and volume based on the Hurst coefficient of Earth's surface, which provides a mechanistic connection between lake area and volume. Volume-area scaling based on the Hurst coefficient is accurate and consistent when applied to lake data sets spanning diverse regions. We applied these relationships to a global lake area census to estimate global lake volume and depth. The volume of Earth's lakes is 199,000 km3 (95\\% confidence interval 196,000–202,000 km3). This volume is in the range of historical estimates (166,000–280,000 km3), but the overall mean depth of 41.8 m (95\\% CI 41.2–42.4 m) is significantly lower than previous estimates (62–151 m). These results highlight and constrain the relative scarcity of lake waters in the hydrosphere and have implications for the role of lakes in global biogeochemical cycles.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-03-20},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Cael, B. B. and Heathcote, A. J. and Seekell, David A.},\n\tmonth = jan,\n\tyear = {2017},\n\tnote = {00003},\n\tkeywords = {\\#nosource, 0458 Limnology, 0746 Lakes, Limnology, mean depth, scaling, topograhy, volume},\n\tpages = {2016GL071378},\n}\n\n\n\n\n\n Global lake volume estimates are scarce, highly variable, and poorly documented. We developed a rigorous method for estimating global lake depth and volume based on the Hurst coefficient of Earth's surface, which provides a mechanistic connection between lake area and volume. Volume-area scaling based on the Hurst coefficient is accurate and consistent when applied to lake data sets spanning diverse regions. We applied these relationships to a global lake area census to estimate global lake volume and depth. The volume of Earth's lakes is 199,000 km3 (95% confidence interval 196,000–202,000 km3). This volume is in the range of historical estimates (166,000–280,000 km3), but the overall mean depth of 41.8 m (95% CI 41.2–42.4 m) is significantly lower than previous estimates (62–151 m). These results highlight and constrain the relative scarcity of lake waters in the hydrosphere and have implications for the role of lakes in global biogeochemical cycles.\n
\n\n\n\n \n\n \n \n \n \n \n \n How Do Biota Respond to Additional Physical Restoration of Restored Streams?.\n \n \n \n \n\n\n \n Nilsson, C.; Sarneel, J. M.; Palm, D.; Gardeström, J.; Pilotto, F.; Polvi, L. E.; Lind, L.; Holmqvist, D.; and Lundqvist, H.\n\n\n \n\n\n\n Ecosystems, 20(1): 144–162. January 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{nilsson_how_2017,\n\ttitle = {How {Do} {Biota} {Respond} to {Additional} {Physical} {Restoration} of {Restored} {Streams}?},\n\tvolume = {20},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-016-0020-0},\n\tdoi = {10.1007/s10021-016-0020-0},\n\tabstract = {Restoration of channelized streams by returning coarse sediment from stream edges to the wetted channel has become a common practice in Sweden. Yet, restoration activities do not always result in the return of desired biota. This study evaluated a restoration project in the Vindel River in northern Sweden in which practitioners further increased channel complexity of previously restored stream reaches by placing very large boulders ({\\textgreater}1 m), trees ({\\textgreater}8 m), and salmonid spawning gravel from adjacent upland areas into the channels. One reach restored with basic methods and another with enhanced methods were selected in each of ten different tributaries to the main channel. Geomorphic and hydraulic complexity was enhanced but the chemical composition of riparian soils and the communities of riparian plants and fish did not exhibit any clear responses to the enhanced restoration measures during the first 5 years compared to reaches restored with basic restoration methods. The variation in the collected data was among streams instead of between types of restored reaches. We conclude that restoration is a disturbance in itself, that immigration potential varies across landscapes, and that biotic recovery processes in boreal river systems are slow. We suggest that enhanced restoration has to apply a catchment-scale approach accounting for connectivity and availability of source populations, and that low-intensity monitoring has to be performed over several decades to evaluate restoration outcomes.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2019-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Nilsson, Christer and Sarneel, Judith M. and Palm, Daniel and Gardeström, Johanna and Pilotto, Francesca and Polvi, Lina E. and Lind, Lovisa and Holmqvist, Daniel and Lundqvist, Hans},\n\tmonth = jan,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Sweden, fish, geomorphic complexity, hydraulics, ice, landscape scale, restoration, riparian chemistry, riparian plants},\n\tpages = {144--162},\n}\n\n\n\n\n\n Restoration of channelized streams by returning coarse sediment from stream edges to the wetted channel has become a common practice in Sweden. Yet, restoration activities do not always result in the return of desired biota. This study evaluated a restoration project in the Vindel River in northern Sweden in which practitioners further increased channel complexity of previously restored stream reaches by placing very large boulders (\\textgreater1 m), trees (\\textgreater8 m), and salmonid spawning gravel from adjacent upland areas into the channels. One reach restored with basic methods and another with enhanced methods were selected in each of ten different tributaries to the main channel. Geomorphic and hydraulic complexity was enhanced but the chemical composition of riparian soils and the communities of riparian plants and fish did not exhibit any clear responses to the enhanced restoration measures during the first 5 years compared to reaches restored with basic restoration methods. The variation in the collected data was among streams instead of between types of restored reaches. We conclude that restoration is a disturbance in itself, that immigration potential varies across landscapes, and that biotic recovery processes in boreal river systems are slow. We suggest that enhanced restoration has to apply a catchment-scale approach accounting for connectivity and availability of source populations, and that low-intensity monitoring has to be performed over several decades to evaluate restoration outcomes.\n
\n\n\n\n \n\n \n \n \n \n \n \n New insights on resource stoichiometry: assessing availability of carbon, nitrogen, and phosphorus to bacterioplankton.\n \n \n \n \n\n\n \n Soares, A. R. A.; Bergström, A.; Sponseller, R. A.; Moberg, J. M.; Giesler, R.; Kritzberg, E. S.; Jansson, M.; and Berggren, M.\n\n\n \n\n\n\n Biogeosciences, 14(6): 1527–1539. March 2017.\n 00005\n\n\n\n
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\n\n\n@article{soares_new_2017,\n\ttitle = {New insights on resource stoichiometry: assessing availability of carbon, nitrogen, and phosphorus to bacterioplankton},\n\tvolume = {14},\n\tissn = {1726-4189},\n\tshorttitle = {New insights on resource stoichiometry},\n\turl = {http://www.biogeosciences.net/14/1527/2017/},\n\tdoi = {10.5194/bg-14-1527-2017},\n\tabstract = {Boreal lake and river ecosystems receive large quantities of organic nutrients and carbon (C) from their catchments. How bacterioplankton respond to these inputs is not well understood, in part because we base our understanding and predictions on total pools, yet we know little about the stoichiometry of bioavailable elements within organic matter. We designed bioassays with the purpose of exhausting the pools of readily bioavailable dissolved organic carbon (BDOC), bioavailable dissolved nitrogen (BDN), and bioavailable dissolved phosphorus (BDP) as fast as possible. Applying the method in four boreal lakes at base-flow conditions yielded concentrations of bioavailable resources in the range 105–693 µg C L−1 for BDOC (2 \\% of initial total DOC), 24–288 µg N L−1 for BDN (31 \\% of initial total dissolved nitrogen), and 0.2–17 µg P L−1 for BDP (49 \\% of initial total dissolved phosphorus). Thus, relative bioavailability increased from carbon (C) to nitrogen (N) to phosphorus (P). We show that the main fraction of bioavailable nutrients is organic, representing 80 \\% of BDN and 61 \\% of BDP. In addition, we demonstrate that total C : N and C : P ratios are as much as 13-fold higher than C : N and C : P ratios for bioavailable resource fractions. Further, by applying additional bioavailability measurements to seven widely distributed rivers, we provide support for a general pattern of relatively high bioavailability of P and N in relation to C. Altogether, our findings underscore the poor availability of C for support of bacterial metabolism in boreal C-rich freshwaters, and suggest that these ecosystems are very sensitive to increased input of bioavailable DOC.},\n\tnumber = {6},\n\turldate = {2017-03-28},\n\tjournal = {Biogeosciences},\n\tauthor = {Soares, A. R. A. and Bergström, A.-K. and Sponseller, R. A. and Moberg, J. M. and Giesler, R. and Kritzberg, E. S. and Jansson, M. and Berggren, M.},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {00005},\n\tkeywords = {\\#nosource},\n\tpages = {1527--1539},\n}\n\n\n\n\n\n Boreal lake and river ecosystems receive large quantities of organic nutrients and carbon (C) from their catchments. How bacterioplankton respond to these inputs is not well understood, in part because we base our understanding and predictions on total pools, yet we know little about the stoichiometry of bioavailable elements within organic matter. We designed bioassays with the purpose of exhausting the pools of readily bioavailable dissolved organic carbon (BDOC), bioavailable dissolved nitrogen (BDN), and bioavailable dissolved phosphorus (BDP) as fast as possible. Applying the method in four boreal lakes at base-flow conditions yielded concentrations of bioavailable resources in the range 105–693 µg C L−1 for BDOC (2 % of initial total DOC), 24–288 µg N L−1 for BDN (31 % of initial total dissolved nitrogen), and 0.2–17 µg P L−1 for BDP (49 % of initial total dissolved phosphorus). Thus, relative bioavailability increased from carbon (C) to nitrogen (N) to phosphorus (P). We show that the main fraction of bioavailable nutrients is organic, representing 80 % of BDN and 61 % of BDP. In addition, we demonstrate that total C : N and C : P ratios are as much as 13-fold higher than C : N and C : P ratios for bioavailable resource fractions. Further, by applying additional bioavailability measurements to seven widely distributed rivers, we provide support for a general pattern of relatively high bioavailability of P and N in relation to C. Altogether, our findings underscore the poor availability of C for support of bacterial metabolism in boreal C-rich freshwaters, and suggest that these ecosystems are very sensitive to increased input of bioavailable DOC.\n
\n\n\n\n \n\n \n \n \n \n \n \n Root heterogeneity along an arctic elevational gradient: the importance of resolution.\n \n \n \n \n\n\n \n Träger, S.; and Wilson, S. D.\n\n\n \n\n\n\n Functional Ecology, 31(2): 480–487. February 2017.\n 00001\n\n\n\n
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\n\n\n@article{trager_root_2017,\n\ttitle = {Root heterogeneity along an arctic elevational gradient: the importance of resolution},\n\tvolume = {31},\n\tissn = {1365-2435},\n\tshorttitle = {Root heterogeneity along an arctic elevational gradient},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12721/abstract},\n\tdoi = {10.1111/1365-2435.12721},\n\tabstract = {* Spatial heterogeneity affects plant performance and is influenced by plants, but the scale at which fine roots react to or generate spatial heterogeneity has received little attention. Fine roots might be expected to respond to heterogeneity at a scale comparable to their diameter (mm), but studies to date have been conducted at much coarser resolutions (cm – m). Here we quantify root heterogeneity in contrasting habitats with special attention to the influence of resolution.\n\n\n* We measured fine root length heterogeneity at resolutions ranging from 1 to 300 mm2, at four elevations along an arctic alpine gradient from 500 m a.s.l. (forest) to 1100 m (tundra). We calculated the magnitude of heterogeneity as the coefficient of variation of root length, and the scale of heterogeneity using semivariance analysis.\n\n\n* The magnitude of heterogeneity was about twofold greater at fine than coarse resolution. Further, the magnitude of heterogeneity was generally greatest at the highest elevation, suggesting that soil at 1100 m was less evenly occupied by plant roots than soils at lower elevations. The exception to this was at the 1 mm2 resolution, for which the magnitude of heterogeneity did not vary with elevation, possibly because heterogeneity at this scale is related to ecophysiological processes common to all vegetation types.\n\n\n* The scale of root length heterogeneity increased significantly with resolution coarseness, suggesting that roots respond to or generate patchiness at small scales that have not previously been examined. In contrast, the scale of heterogeneity did not vary significantly with elevation and the accompanying turnover in growth form.\n\n\n* Our results suggest that roots in four vegetation types respond to or generate very fine scales of spatial heterogeneity, including scales much smaller than those that have previously been examined. Both the magnitude and scale of heterogeneity varied with sampling resolution, suggesting resolutions as small as a few millimetres are relevant to studies of spatial root interactions and below-ground processes.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-11-17},\n\tjournal = {Functional Ecology},\n\tauthor = {Träger, Sabrina and Wilson, Scott D.},\n\tmonth = feb,\n\tyear = {2017},\n\tnote = {00001},\n\tkeywords = {\\#nosource, alpine, forest, minirhizotron, patchiness, root length, semivariance, tundra},\n\tpages = {480--487},\n}\n\n\n\n\n\n * Spatial heterogeneity affects plant performance and is influenced by plants, but the scale at which fine roots react to or generate spatial heterogeneity has received little attention. Fine roots might be expected to respond to heterogeneity at a scale comparable to their diameter (mm), but studies to date have been conducted at much coarser resolutions (cm – m). Here we quantify root heterogeneity in contrasting habitats with special attention to the influence of resolution. * We measured fine root length heterogeneity at resolutions ranging from 1 to 300 mm2, at four elevations along an arctic alpine gradient from 500 m a.s.l. (forest) to 1100 m (tundra). We calculated the magnitude of heterogeneity as the coefficient of variation of root length, and the scale of heterogeneity using semivariance analysis. * The magnitude of heterogeneity was about twofold greater at fine than coarse resolution. Further, the magnitude of heterogeneity was generally greatest at the highest elevation, suggesting that soil at 1100 m was less evenly occupied by plant roots than soils at lower elevations. The exception to this was at the 1 mm2 resolution, for which the magnitude of heterogeneity did not vary with elevation, possibly because heterogeneity at this scale is related to ecophysiological processes common to all vegetation types. * The scale of root length heterogeneity increased significantly with resolution coarseness, suggesting that roots respond to or generate patchiness at small scales that have not previously been examined. In contrast, the scale of heterogeneity did not vary significantly with elevation and the accompanying turnover in growth form. * Our results suggest that roots in four vegetation types respond to or generate very fine scales of spatial heterogeneity, including scales much smaller than those that have previously been examined. Both the magnitude and scale of heterogeneity varied with sampling resolution, suggesting resolutions as small as a few millimetres are relevant to studies of spatial root interactions and below-ground processes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Composition of riparian litter input regulates organic matter decomposition: Implications for headwater stream functioning in a managed forest landscape.\n \n \n \n \n\n\n \n Lidman, J.; Jonsson, M.; Burrows, R. M.; Bundschuh, M.; and Sponseller, R. A.\n\n\n \n\n\n\n Ecology and Evolution, 7(4): 1068–1077. February 2017.\n 00000\n\n\n\n
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\n\n\n@article{lidman_composition_2017,\n\ttitle = {Composition of riparian litter input regulates organic matter decomposition: {Implications} for headwater stream functioning in a managed forest landscape},\n\tvolume = {7},\n\tissn = {2045-7758},\n\tshorttitle = {Composition of riparian litter input regulates organic matter decomposition},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/ece3.2726/abstract},\n\tdoi = {10.1002/ece3.2726},\n\tabstract = {Although the importance of stream condition for leaf litter decomposition has been extensively studied, little is known about how processing rates change in response to altered riparian vegetation community composition. We investigated patterns of plant litter input and decomposition across 20 boreal headwater streams that varied in proportions of riparian deciduous and coniferous trees. We measured a suite of in-stream physical and chemical characteristics, as well as the amount and type of litter inputs from riparian vegetation, and related these to decomposition rates of native (alder, birch, and spruce) and introduced (lodgepole pine) litter species incubated in coarse- and fine-mesh bags. Total litter inputs ranged more than fivefold among sites and increased with the proportion of deciduous vegetation in the riparian zone. In line with differences in initial litter quality, mean decomposition rate was highest for alder, followed by birch, spruce, and lodgepole pine (12, 55, and 68\\% lower rates, respectively). Further, these rates were greater in coarse-mesh bags that allow colonization by macroinvertebrates. Variance in decomposition rate among sites for different species was best explained by different sets of environmental conditions, but litter-input composition (i.e., quality) was overall highly important. On average, native litter decomposed faster in sites with higher-quality litter input and (with the exception of spruce) higher concentrations of dissolved nutrients and open canopies. By contrast, lodgepole pine decomposed more rapidly in sites receiving lower-quality litter inputs. Birch litter decomposition rate in coarse-mesh bags was best predicted by the same environmental variables as in fine-mesh bags, with additional positive influences of macroinvertebrate species richness. Hence, to facilitate energy turnover in boreal headwaters, forest management with focus on conifer production should aim at increasing the presence of native deciduous trees along streams, as they promote conditions that favor higher decomposition rates of terrestrial plant litter.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-11-17},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Lidman, Johan and Jonsson, Micael and Burrows, Ryan M. and Bundschuh, Mirco and Sponseller, Ryan A.},\n\tmonth = feb,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, boreal, introduced species, land use, litter quality, priming effect},\n\tpages = {1068--1077},\n}\n\n\n\n\n\n Although the importance of stream condition for leaf litter decomposition has been extensively studied, little is known about how processing rates change in response to altered riparian vegetation community composition. We investigated patterns of plant litter input and decomposition across 20 boreal headwater streams that varied in proportions of riparian deciduous and coniferous trees. We measured a suite of in-stream physical and chemical characteristics, as well as the amount and type of litter inputs from riparian vegetation, and related these to decomposition rates of native (alder, birch, and spruce) and introduced (lodgepole pine) litter species incubated in coarse- and fine-mesh bags. Total litter inputs ranged more than fivefold among sites and increased with the proportion of deciduous vegetation in the riparian zone. In line with differences in initial litter quality, mean decomposition rate was highest for alder, followed by birch, spruce, and lodgepole pine (12, 55, and 68% lower rates, respectively). Further, these rates were greater in coarse-mesh bags that allow colonization by macroinvertebrates. Variance in decomposition rate among sites for different species was best explained by different sets of environmental conditions, but litter-input composition (i.e., quality) was overall highly important. On average, native litter decomposed faster in sites with higher-quality litter input and (with the exception of spruce) higher concentrations of dissolved nutrients and open canopies. By contrast, lodgepole pine decomposed more rapidly in sites receiving lower-quality litter inputs. Birch litter decomposition rate in coarse-mesh bags was best predicted by the same environmental variables as in fine-mesh bags, with additional positive influences of macroinvertebrate species richness. Hence, to facilitate energy turnover in boreal headwaters, forest management with focus on conifer production should aim at increasing the presence of native deciduous trees along streams, as they promote conditions that favor higher decomposition rates of terrestrial plant litter.\n
\n\n\n\n \n\n \n \n \n \n \n \n Multiple sources and sinks of dissolved inorganic carbon across Swedish streams, refocusing the lens of stable C isotopes.\n \n \n \n \n\n\n \n Campeau, A.; Wallin, M. B.; Giesler, R.; Löfgren, S.; Mörth, C.; Schiff, S.; Venkiteswaran, J. J.; and Bishop, K.\n\n\n \n\n\n\n Scientific Reports, 7(1): 9158. August 2017.\n 00000\n\n\n\n
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\n\n\n@article{campeau_multiple_2017,\n\ttitle = {Multiple sources and sinks of dissolved inorganic carbon across {Swedish} streams, refocusing the lens of stable {C} isotopes},\n\tvolume = {7},\n\tcopyright = {2017 The Author(s)},\n\tissn = {2045-2322},\n\turl = {https://www.nature.com/articles/s41598-017-09049-9},\n\tdoi = {10.1038/s41598-017-09049-9},\n\tabstract = {It is well established that stream dissolved inorganic carbon (DIC) fluxes play a central role in the global C cycle, yet the sources of stream DIC remain to a large extent unresolved. Here, we explore large-scale patterns in δ13C-DIC from streams across Sweden to separate and further quantify the sources and sinks of stream DIC. We found that stream DIC is governed by a variety of sources and sinks including biogenic and geogenic sources, CO2 evasion, as well as in-stream processes. Although soil respiration was the main source of DIC across all streams, a geogenic DIC influence was identified in the northernmost region. All streams were affected by various degrees of atmospheric CO2 evasion, but residual variance in δ13C-DIC also indicated a significant influence of in-stream metabolism and anaerobic processes. Due to those multiple sources and sinks, we emphasize that simply quantifying aquatic DIC fluxes will not be sufficient to characterise their role in the global C cycle.},\n\tlanguage = {En},\n\tnumber = {1},\n\turldate = {2017-11-17},\n\tjournal = {Scientific Reports},\n\tauthor = {Campeau, Audrey and Wallin, Marcus B. and Giesler, Reiner and Löfgren, Stefan and Mörth, Carl-Magnus and Schiff, Sherry and Venkiteswaran, Jason J. and Bishop, Kevin},\n\tmonth = aug,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {9158},\n}\n\n\n\n\n\n It is well established that stream dissolved inorganic carbon (DIC) fluxes play a central role in the global C cycle, yet the sources of stream DIC remain to a large extent unresolved. Here, we explore large-scale patterns in δ13C-DIC from streams across Sweden to separate and further quantify the sources and sinks of stream DIC. We found that stream DIC is governed by a variety of sources and sinks including biogenic and geogenic sources, CO2 evasion, as well as in-stream processes. Although soil respiration was the main source of DIC across all streams, a geogenic DIC influence was identified in the northernmost region. All streams were affected by various degrees of atmospheric CO2 evasion, but residual variance in δ13C-DIC also indicated a significant influence of in-stream metabolism and anaerobic processes. Due to those multiple sources and sinks, we emphasize that simply quantifying aquatic DIC fluxes will not be sufficient to characterise their role in the global C cycle.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon dynamics at frost-patterned tundra driven by long-term vegetation change rather than by short-term non-growing season warming.\n \n \n \n \n\n\n \n Väisänen, M.; Krab, E. J.; and Dorrepaal, E.\n\n\n \n\n\n\n Biogeochemistry, 136(1): 103–117. October 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{vaisanen_carbon_2017,\n\ttitle = {Carbon dynamics at frost-patterned tundra driven by long-term vegetation change rather than by short-term non-growing season warming},\n\tvolume = {136},\n\tissn = {0168-2563, 1573-515X},\n\turl = {https://link.springer.com/article/10.1007/s10533-017-0385-y},\n\tdoi = {10.1007/s10533-017-0385-y},\n\tabstract = {Frost-patterned grounds, such as mostly barren frost boils surrounded by denser vegetation, are typical habitat mosaics in tundra. Plant and microbial processes in these habitats may be susceptible to short-term warming outside the growing season, while the areal cover of barren frost boils has decreased during the past decades due to climate warming-induced shrub expansion. The relative importance of such short-term and long-term climate impacts on carbon (C) dynamics remains unknown. We measured ecosystem CO2 uptake and release (in the field), microbial respiration (in the laboratory), as well as microbial biomass N and soil extractable N in frost boils and the directly adjacent heath in late spring and late summer. These habitats had been experimentally warmed with insulating fleeces from late September until late May for three consecutive years, which allowed us to investigate the direct short-term effects of warming and longer-term, indirect climate effects via vegetation establishment into frost boils. Non-growing season warming increased C uptake at the frost boils in late spring and decreased it in late summer, while the timing and direction of responses was opposite for the heath. Experimental warming had no effects on microbial or ecosystem C release or soil N at either of the habitats. However, C cycling was manifold higher at the heath compared to the frost boils, likely because of a higher SOM stock in the soil. Short-term climate change can thus directly alter ecosystem C uptake at frost-patterned grounds but will most likely not affect microbial C release. We conclude that the C dynamics at frost-patterned grounds under a changing climate depend most strongly on the potential of vegetation to encroach into frost boils in the long-term.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-11-17},\n\tjournal = {Biogeochemistry},\n\tauthor = {Väisänen, Maria and Krab, Eveline J. and Dorrepaal, Ellen},\n\tmonth = oct,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {103--117},\n}\n\n\n\n\n\n Frost-patterned grounds, such as mostly barren frost boils surrounded by denser vegetation, are typical habitat mosaics in tundra. Plant and microbial processes in these habitats may be susceptible to short-term warming outside the growing season, while the areal cover of barren frost boils has decreased during the past decades due to climate warming-induced shrub expansion. The relative importance of such short-term and long-term climate impacts on carbon (C) dynamics remains unknown. We measured ecosystem CO2 uptake and release (in the field), microbial respiration (in the laboratory), as well as microbial biomass N and soil extractable N in frost boils and the directly adjacent heath in late spring and late summer. These habitats had been experimentally warmed with insulating fleeces from late September until late May for three consecutive years, which allowed us to investigate the direct short-term effects of warming and longer-term, indirect climate effects via vegetation establishment into frost boils. Non-growing season warming increased C uptake at the frost boils in late spring and decreased it in late summer, while the timing and direction of responses was opposite for the heath. Experimental warming had no effects on microbial or ecosystem C release or soil N at either of the habitats. However, C cycling was manifold higher at the heath compared to the frost boils, likely because of a higher SOM stock in the soil. Short-term climate change can thus directly alter ecosystem C uptake at frost-patterned grounds but will most likely not affect microbial C release. We conclude that the C dynamics at frost-patterned grounds under a changing climate depend most strongly on the potential of vegetation to encroach into frost boils in the long-term.\n
\n\n\n\n \n\n \n \n \n \n \n \n Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species.\n \n \n \n \n\n\n \n Keuper, F.; Dorrepaal, E.; van Bodegom, P. M.; van Logtestijn, R.; Venhuizen, G.; van Hal, J.; and Aerts, R.\n\n\n \n\n\n\n Global Change Biology, 23(10): 4257–4266. October 2017.\n 00000\n\n\n\n
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\n\n\n@article{keuper_experimentally_2017,\n\ttitle = {Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species},\n\tvolume = {23},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.13804/abstract},\n\tdoi = {10.1111/gcb.13804},\n\tabstract = {Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such changes may substantially affect net primary production and species composition. We aimed to identify the potential impact of increased N-availability due to permafrost thawing on subarctic peatland plant production and species performance, relative to the impact of increased N-availability in superficial organic layers. Therefore, we investigated whether plant roots are present at the thaw-front (45 cm depth) and whether N-uptake (15N-tracer) at the thaw-front occurs during maximum thaw-depth, coinciding with the end of the growing season. Moreover, we performed a unique 3-year belowground fertilization experiment with fully factorial combinations of deep- (thaw-front) and shallow-fertilization (10 cm depth) and controls. We found that certain species are present with roots at the thaw-front (Rubus chamaemorus) and have the capacity (R. chamaemorus, Eriophorum vaginatum) for N-uptake from the thaw-front between autumn and spring when aboveground tissue is largely senescent. In response to 3-year shallow-belowground fertilization (S) both shallow- (Empetrum hermaphroditum) and deep-rooting species increased aboveground biomass and N-content, but only deep-rooting species responded positively to enhanced nutrient supply at the thaw-front (D). Moreover, the effects of shallow-fertilization and thaw-front fertilization on aboveground biomass production of the deep-rooting species were similar in magnitude (S: 71\\%; D: 111\\% increase compared to control) and additive (S + D: 181\\% increase). Our results show that plant-available N released from thawing permafrost can form a thus far overlooked additional N-source for deep-rooting subarctic plant species and increase their biomass production beyond the already established impact of warming-driven enhanced shallow N-mineralization. This may result in shifts in plant community composition and may partially counteract the increased carbon losses from thawing permafrost.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2017-11-17},\n\tjournal = {Global Change Biology},\n\tauthor = {Keuper, Frida and Dorrepaal, Ellen and van Bodegom, Peter M. and van Logtestijn, Richard and Venhuizen, Gemma and van Hal, Jurgen and Aerts, Rien},\n\tmonth = oct,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Empetrum hermaphroditum, Rubus chamaemorus, belowground nitrogen, climate change, fertilization, frozen soil, permafrost thaw, root uptake},\n\tpages = {4257--4266},\n}\n\n\n\n\n\n Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such changes may substantially affect net primary production and species composition. We aimed to identify the potential impact of increased N-availability due to permafrost thawing on subarctic peatland plant production and species performance, relative to the impact of increased N-availability in superficial organic layers. Therefore, we investigated whether plant roots are present at the thaw-front (45 cm depth) and whether N-uptake (15N-tracer) at the thaw-front occurs during maximum thaw-depth, coinciding with the end of the growing season. Moreover, we performed a unique 3-year belowground fertilization experiment with fully factorial combinations of deep- (thaw-front) and shallow-fertilization (10 cm depth) and controls. We found that certain species are present with roots at the thaw-front (Rubus chamaemorus) and have the capacity (R. chamaemorus, Eriophorum vaginatum) for N-uptake from the thaw-front between autumn and spring when aboveground tissue is largely senescent. In response to 3-year shallow-belowground fertilization (S) both shallow- (Empetrum hermaphroditum) and deep-rooting species increased aboveground biomass and N-content, but only deep-rooting species responded positively to enhanced nutrient supply at the thaw-front (D). Moreover, the effects of shallow-fertilization and thaw-front fertilization on aboveground biomass production of the deep-rooting species were similar in magnitude (S: 71%; D: 111% increase compared to control) and additive (S + D: 181% increase). Our results show that plant-available N released from thawing permafrost can form a thus far overlooked additional N-source for deep-rooting subarctic plant species and increase their biomass production beyond the already established impact of warming-driven enhanced shallow N-mineralization. This may result in shifts in plant community composition and may partially counteract the increased carbon losses from thawing permafrost.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal resource limitation of heterotrophic biofilms in boreal streams.\n \n \n \n \n\n\n \n Burrows, R. M.; Laudon, H.; McKie, B. G.; and Sponseller, R. A.\n\n\n \n\n\n\n Limnology and Oceanography, 62(1): 164–176. January 2017.\n 00000\n\n\n\n
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\n\n\n@article{burrows_seasonal_2017,\n\ttitle = {Seasonal resource limitation of heterotrophic biofilms in boreal streams},\n\tvolume = {62},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/lno.10383/abstract},\n\tdoi = {10.1002/lno.10383},\n\tabstract = {Unraveling the potentially shifting controls over microbial activity among habitats and across seasonal transitions is critical for understanding how freshwater ecosystems influence broader elemental cycles, and how these systems may respond to global changes. We used nutrient-diffusing substrates to investigate seasonal patterns and constraints on microbial activity of biofilms in streams draining distinct landscape features of the boreal biome (forests, mires, and lakes). Microbial respiration (MR) largely mirrored spatial and temporal variation in water temperature. However, limitation by labile carbon (C) was a constraint to microbial activity during ice-covered periods, when MR of control nutrient-diffusing substrates fell below rates predicted from stream temperature alone. Variation in C limitation among the study streams was reflective of putative organic C availability, with C limitation of biofilms weakest in the dissolved organic C (DOC)-rich, mire-outlet stream and greatest in the relatively DOC-poor, forest stream. Incidences of nutrient limitation were only observed during warmer months. Our study illustrates how variation in processes mediated by heterotrophic biofilms and seasonal shifts in resource limitation can emerge in a stream network draining a heterogeneous landscape. In addition, our results show that, for a large portion of the year, heterotrophic processes in boreal streams can be strongly limited by the availability of labile C, despite high DOC concentrations. Metabolic constraints to dissolved organic matter processing at near-freezing temperatures, coupled with hydrological controls over the delivery of more labile organic resources to streams (e.g., soil freezing and flooding), have potentially strong influences on the productivity of boreal streams.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-11-17},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Burrows, Ryan M. and Laudon, Hjalmar and McKie, Brendan G. and Sponseller, Ryan A.},\n\tmonth = jan,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Boreal forest, Dissolved organic carbon, Metabolism, Microbial processing, Resource limitation, Wetlands},\n\tpages = {164--176},\n}\n\n\n\n\n\n Unraveling the potentially shifting controls over microbial activity among habitats and across seasonal transitions is critical for understanding how freshwater ecosystems influence broader elemental cycles, and how these systems may respond to global changes. We used nutrient-diffusing substrates to investigate seasonal patterns and constraints on microbial activity of biofilms in streams draining distinct landscape features of the boreal biome (forests, mires, and lakes). Microbial respiration (MR) largely mirrored spatial and temporal variation in water temperature. However, limitation by labile carbon (C) was a constraint to microbial activity during ice-covered periods, when MR of control nutrient-diffusing substrates fell below rates predicted from stream temperature alone. Variation in C limitation among the study streams was reflective of putative organic C availability, with C limitation of biofilms weakest in the dissolved organic C (DOC)-rich, mire-outlet stream and greatest in the relatively DOC-poor, forest stream. Incidences of nutrient limitation were only observed during warmer months. Our study illustrates how variation in processes mediated by heterotrophic biofilms and seasonal shifts in resource limitation can emerge in a stream network draining a heterogeneous landscape. In addition, our results show that, for a large portion of the year, heterotrophic processes in boreal streams can be strongly limited by the availability of labile C, despite high DOC concentrations. Metabolic constraints to dissolved organic matter processing at near-freezing temperatures, coupled with hydrological controls over the delivery of more labile organic resources to streams (e.g., soil freezing and flooding), have potentially strong influences on the productivity of boreal streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n To what extent is the DNA of microbial eukaryotes modified during burying into lake sediments? A repeat-coring approach on annually laminated sediments.\n \n \n \n \n\n\n \n Capo, E.; Domaizon, I.; Maier, D.; Debroas, D.; and Bigler, C.\n\n\n \n\n\n\n Journal of Paleolimnology, 58(4): 479–495. December 2017.\n 00000\n\n\n\n
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\n\n\n@article{capo_what_2017,\n\ttitle = {To what extent is the {DNA} of microbial eukaryotes modified during burying into lake sediments? {A} repeat-coring approach on annually laminated sediments},\n\tvolume = {58},\n\tissn = {0921-2728, 1573-0417},\n\tshorttitle = {To what extent is the {DNA} of microbial eukaryotes modified during burying into lake sediments?},\n\turl = {https://link.springer.com/article/10.1007/s10933-017-0005-9},\n\tdoi = {10.1007/s10933-017-0005-9},\n\tabstract = {Paleogenetics provides a powerful framework to reconstruct the long-term temporal dynamics of various biological groups from aquatic sediments. However, validations are still required to ensure the authenticity of the molecular signal obtained from sedimentary DNA. Here, we investigated the effects of early diagenesis on the DNA signal from micro-eukaryotes preserved in sediments by comparing metabarcoding inventories obtained for two sediment cores sampled in 2007 and 2013 respectively. High-throughput sequencing (Illumina MiSeq) of sedimentary DNA was utilized to reconstruct the composition of microbial eukaryotic communities by targeting the V7 region of the 18S rDNA gene. No significant difference was detected between the molecular inventories obtained for the two cores both for total richness and diversity indices. Moreover, community structures obtained for the two cores were congruent as revealed by procrustean analysis. Though most of the eukaryotic groups showed no significant difference in terms of richness and relative proportion according to the core, the group of fungi was found to differ both in terms of richness and relative proportion (possibly due to their spatial heterogeneity and potential activity in sediments). Considering the OTUs level (i.e. Operational Taxonomic Units as a proxy of ecological species), our results showed that, for the older analyzed strata (age: 15–40 years), the composition and structure of communities were very similar for the two cores (except for fungi) and the DNA signal was considered stable. However, for the uppermost strata (age {\\textless} 15 years), changes of moderate magnitude were detected in the relative abundance of few OTUs. Overall, this study points out that, in Nylandssjön sediments, early diagenesis did not induce marked modifications in the micro-eukaryotic DNA signal, thus opening new perspectives based on the analysis of eukaryotic sedimentary DNA to address scientific issues both in the domains of paleolimnology and microbial ecology. Because this study site is ideal for DNA preservation in sediment (quick sedimentation processes, no sediment resuspension, anoxic conditions at sediment–water interface), the generalization of our conclusions, in particular for less favorable sites, must be considered cautiously.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-11-17},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Capo, Eric and Domaizon, Isabelle and Maier, Dominique and Debroas, Didier and Bigler, Christian},\n\tmonth = dec,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {479--495},\n}\n\n\n\n\n\n Paleogenetics provides a powerful framework to reconstruct the long-term temporal dynamics of various biological groups from aquatic sediments. However, validations are still required to ensure the authenticity of the molecular signal obtained from sedimentary DNA. Here, we investigated the effects of early diagenesis on the DNA signal from micro-eukaryotes preserved in sediments by comparing metabarcoding inventories obtained for two sediment cores sampled in 2007 and 2013 respectively. High-throughput sequencing (Illumina MiSeq) of sedimentary DNA was utilized to reconstruct the composition of microbial eukaryotic communities by targeting the V7 region of the 18S rDNA gene. No significant difference was detected between the molecular inventories obtained for the two cores both for total richness and diversity indices. Moreover, community structures obtained for the two cores were congruent as revealed by procrustean analysis. Though most of the eukaryotic groups showed no significant difference in terms of richness and relative proportion according to the core, the group of fungi was found to differ both in terms of richness and relative proportion (possibly due to their spatial heterogeneity and potential activity in sediments). Considering the OTUs level (i.e. Operational Taxonomic Units as a proxy of ecological species), our results showed that, for the older analyzed strata (age: 15–40 years), the composition and structure of communities were very similar for the two cores (except for fungi) and the DNA signal was considered stable. However, for the uppermost strata (age \\textless 15 years), changes of moderate magnitude were detected in the relative abundance of few OTUs. Overall, this study points out that, in Nylandssjön sediments, early diagenesis did not induce marked modifications in the micro-eukaryotic DNA signal, thus opening new perspectives based on the analysis of eukaryotic sedimentary DNA to address scientific issues both in the domains of paleolimnology and microbial ecology. Because this study site is ideal for DNA preservation in sediment (quick sedimentation processes, no sediment resuspension, anoxic conditions at sediment–water interface), the generalization of our conclusions, in particular for less favorable sites, must be considered cautiously.\n
\n\n\n\n \n\n \n \n \n \n \n \n Investigating molecular changes in organic matter composition in two Holocene lake-sediment records from central Sweden using pyrolysis-GC/MS.\n \n \n \n \n\n\n \n Ninnes, S.; Tolu, J.; Meyer-Jacob, C.; Mighall, T. M.; and Bindler, R.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 122(6): 2016JG003715. June 2017.\n 00000\n\n\n\n
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\n\n\n@article{ninnes_investigating_2017,\n\ttitle = {Investigating molecular changes in organic matter composition in two {Holocene} lake-sediment records from central {Sweden} using pyrolysis-{GC}/{MS}},\n\tvolume = {122},\n\tissn = {2169-8961},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/2016JG003715/abstract},\n\tdoi = {10.1002/2016JG003715},\n\tabstract = {Organic matter (OM) is a key component of lake sediments, affecting carbon, nutrient, and trace metal cycling at local and global scales. Yet little is known about long-term (millennial) changes in OM composition due to the inherent chemical complexity arising from multiple OM sources and from secondary transformations. In this study we explore how the molecular composition of OM changes throughout the Holocene in two adjacent boreal lakes in central Sweden and compare molecular-level information with conventional OM variables, including total carbon, total nitrogen, C:N ratios, δ13C, and δ15N. To characterize the molecular OM composition, we employed a new method based on pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), which yields semiquantitative data on {\\textgreater}100 organic compounds of different origin and degradation status. We identify large changes in OM composition after deglaciation (circa 8500 ± 500 B.C.), associated with early landscape development, and during the most recent 40–50 years, driven by degradation processes. With molecular-level information we can also distinguish between natural landscape development and human catchment disturbance during the last 1700 years. Our study demonstrates that characterization of the molecular OM composition by the high-throughput Py-GC/MS method is an efficient complement to conventional OM variables for identification and understanding of past OM dynamics in lake-sediment records. Holocene changes observed for pyrolytic compounds and compound classes known for having different reactivity indicate the need for further paleo-reconstruction of the molecular OM composition to better understand both past and future OM dynamics and associated environmental changes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-11-17},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Ninnes, Sofia and Tolu, Julie and Meyer-Jacob, Carsten and Mighall, Tim M. and Bindler, Richard},\n\tmonth = jun,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, 0420 Biomolecular and chemical tracers, 1055 Organic and biogenic geochemistry, Holocene, carbon, lake sediment, organic matter composition, pyrolysis-GC/MS, stable isotopes},\n\tpages = {2016JG003715},\n}\n\n\n\n\n\n Organic matter (OM) is a key component of lake sediments, affecting carbon, nutrient, and trace metal cycling at local and global scales. Yet little is known about long-term (millennial) changes in OM composition due to the inherent chemical complexity arising from multiple OM sources and from secondary transformations. In this study we explore how the molecular composition of OM changes throughout the Holocene in two adjacent boreal lakes in central Sweden and compare molecular-level information with conventional OM variables, including total carbon, total nitrogen, C:N ratios, δ13C, and δ15N. To characterize the molecular OM composition, we employed a new method based on pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), which yields semiquantitative data on \\textgreater100 organic compounds of different origin and degradation status. We identify large changes in OM composition after deglaciation (circa 8500 ± 500 B.C.), associated with early landscape development, and during the most recent 40–50 years, driven by degradation processes. With molecular-level information we can also distinguish between natural landscape development and human catchment disturbance during the last 1700 years. Our study demonstrates that characterization of the molecular OM composition by the high-throughput Py-GC/MS method is an efficient complement to conventional OM variables for identification and understanding of past OM dynamics in lake-sediment records. Holocene changes observed for pyrolytic compounds and compound classes known for having different reactivity indicate the need for further paleo-reconstruction of the molecular OM composition to better understand both past and future OM dynamics and associated environmental changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Pelagic food web response to whole lake N fertilization.\n \n \n \n \n\n\n \n Deininger, A.; Faithfull, C. L.; Karlsson, J.; Klaus, M.; and Bergström, A.\n\n\n \n\n\n\n Limnology and Oceanography, 62(4): 1498–1511. July 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{deininger_pelagic_2017,\n\ttitle = {Pelagic food web response to whole lake {N} fertilization},\n\tvolume = {62},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/lno.10513/abstract},\n\tdoi = {10.1002/lno.10513},\n\tabstract = {Anthropogenic activities are increasing inorganic nitrogen (N) loadings to unproductive boreal lakes. In many of these lakes phytoplankton are N limited, consequently N fertilization may affect ecosystem productivity and consumer resource use. Here, we conducted whole lake inorganic N fertilization experiments with six small N limited unproductive boreal lakes (three control and three N enriched) in an area receiving low N deposition with one reference and two impact years. Our aim was to assess the effects of N fertilization on pelagic biomass production and consumer resource use. We found that phytoplankton primary production (PP) and biomass, and the PP: bacterioplankton production ratio increased after fertilization. As expected, the relative contribution of phytoplankton derived resources (autochthony) that supported the crustacean zooplankton community increased. Yet, the response in the consumer community was modest with autochthony only increasing in one of the three major zooplankton groups and with no effect on zooplankton biomass. In conclusion, our findings imply that newly available phytoplankton energy derived from N fertilization was not efficiently transferred up to zooplankton, indicating a mismatch between producer energy supply and consumer energy use with potential accumulation of phytoplankton biomass as the result.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-09-11},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Deininger, A. and Faithfull, C. L. and Karlsson, J. and Klaus, M. and Bergström, A.-K.},\n\tmonth = jul,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {1498--1511},\n}\n\n\n\n\n\n Anthropogenic activities are increasing inorganic nitrogen (N) loadings to unproductive boreal lakes. In many of these lakes phytoplankton are N limited, consequently N fertilization may affect ecosystem productivity and consumer resource use. Here, we conducted whole lake inorganic N fertilization experiments with six small N limited unproductive boreal lakes (three control and three N enriched) in an area receiving low N deposition with one reference and two impact years. Our aim was to assess the effects of N fertilization on pelagic biomass production and consumer resource use. We found that phytoplankton primary production (PP) and biomass, and the PP: bacterioplankton production ratio increased after fertilization. As expected, the relative contribution of phytoplankton derived resources (autochthony) that supported the crustacean zooplankton community increased. Yet, the response in the consumer community was modest with autochthony only increasing in one of the three major zooplankton groups and with no effect on zooplankton biomass. In conclusion, our findings imply that newly available phytoplankton energy derived from N fertilization was not efficiently transferred up to zooplankton, indicating a mismatch between producer energy supply and consumer energy use with potential accumulation of phytoplankton biomass as the result.\n
\n\n\n\n \n\n \n \n \n \n \n \n How important are terrestrial organic carbon inputs for secondary production in freshwater ecosystems?.\n \n \n \n \n\n\n \n Brett, M. T.; Bunn, S. E.; Chandra, S.; Galloway, A. W. E.; Guo, F.; Kainz, M. J.; Kankaala, P.; Lau, D. C. P.; Moulton, T. P.; Power, M. E.; Rasmussen, J. B.; Taipale, S. J.; Thorp, J. H.; and Wehr, J. D.\n\n\n \n\n\n\n Freshwater Biology, 62(5): 833–853. May 2017.\n 00000\n\n\n\n
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\n\n\n@article{brett_how_2017,\n\ttitle = {How important are terrestrial organic carbon inputs for secondary production in freshwater ecosystems?},\n\tvolume = {62},\n\tissn = {1365-2427},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/fwb.12909/abstract},\n\tdoi = {10.1111/fwb.12909},\n\tabstract = {* Many freshwater systems receive substantial inputs of terrestrial organic matter. Terrestrially derived dissolved organic carbon (t-DOC) inputs can modify light availability, the spatial distribution of primary production, heat, and oxygen in aquatic systems, as well as inorganic nutrient bioavailability. It is also well-established that some terrestrial inputs (such as invertebrates and fruits) provide high-quality food resources for consumers in some systems.\n\n\n* In small to moderate-sized streams, leaf litter inputs average approximately three times greater than the autochthonous production. Conversely, in oligo/mesotrophic lakes algal production is typically five times greater than the available flux of allochthonous basal resources.\n\n\n* Terrestrial particulate organic carbon (t-POC) inputs to lakes and rivers are comprised of 80\\%–90\\% biochemically recalcitrant lignocellulose, which is highly resistant to enzymatic breakdown by animal consumers. Further, t-POC and heterotrophic bacteria lack essential biochemical compounds that are critical for rapid growth and reproduction in aquatic invertebrates and fishes. Several studies have directly shown that these resources have very low food quality for herbivorous zooplankton and benthic invertebrates.\n\n\n* Much of the nitrogen assimilated by stream consumers is probably of algal origin, even in systems where there appears to be a significant terrestrial carbon contribution. Amino acid stable isotope analyses for large river food webs indicate that most upper trophic level essential amino acids are derived from algae. Similarly, profiles of essential fatty acids in consumers show a strong dependence on the algal food resources.\n\n\n* Primary production to respiration ratios are not a meaningful index to assess consumer allochthony because respiration represents an oxidised carbon flux that cannot be utilised by animal consumers. Rather, the relative importance of allochthonous subsidies for upper trophic level production should be addressed by considering the rates at which terrestrial and autochthonous resources are consumed and the growth efficiency supported by this food.\n\n\n* Ultimately, the biochemical composition of a particular basal resource, and not just its quantity or origin, determines how readily this material is incorporated into upper trophic level consumers. Because of its highly favourable biochemical composition and greater availability, we conclude that microalgal production supports most animal production in freshwater ecosystems.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-05-27},\n\tjournal = {Freshwater Biology},\n\tauthor = {Brett, Michael T. and Bunn, Stuart E. and Chandra, Sudeep and Galloway, Aaron W. E. and Guo, Fen and Kainz, Martin J. and Kankaala, Paula and Lau, Danny C. P. and Moulton, Timothy P. and Power, Mary E. and Rasmussen, Joseph B. and Taipale, Sami J. and Thorp, James H. and Wehr, John D.},\n\tmonth = may,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Autochthonous, allochthonous, biochemical composition, freshwater, resource utilisation},\n\tpages = {833--853},\n}\n\n\n\n\n\n * Many freshwater systems receive substantial inputs of terrestrial organic matter. Terrestrially derived dissolved organic carbon (t-DOC) inputs can modify light availability, the spatial distribution of primary production, heat, and oxygen in aquatic systems, as well as inorganic nutrient bioavailability. It is also well-established that some terrestrial inputs (such as invertebrates and fruits) provide high-quality food resources for consumers in some systems. * In small to moderate-sized streams, leaf litter inputs average approximately three times greater than the autochthonous production. Conversely, in oligo/mesotrophic lakes algal production is typically five times greater than the available flux of allochthonous basal resources. * Terrestrial particulate organic carbon (t-POC) inputs to lakes and rivers are comprised of 80%–90% biochemically recalcitrant lignocellulose, which is highly resistant to enzymatic breakdown by animal consumers. Further, t-POC and heterotrophic bacteria lack essential biochemical compounds that are critical for rapid growth and reproduction in aquatic invertebrates and fishes. Several studies have directly shown that these resources have very low food quality for herbivorous zooplankton and benthic invertebrates. * Much of the nitrogen assimilated by stream consumers is probably of algal origin, even in systems where there appears to be a significant terrestrial carbon contribution. Amino acid stable isotope analyses for large river food webs indicate that most upper trophic level essential amino acids are derived from algae. Similarly, profiles of essential fatty acids in consumers show a strong dependence on the algal food resources. * Primary production to respiration ratios are not a meaningful index to assess consumer allochthony because respiration represents an oxidised carbon flux that cannot be utilised by animal consumers. Rather, the relative importance of allochthonous subsidies for upper trophic level production should be addressed by considering the rates at which terrestrial and autochthonous resources are consumed and the growth efficiency supported by this food. * Ultimately, the biochemical composition of a particular basal resource, and not just its quantity or origin, determines how readily this material is incorporated into upper trophic level consumers. Because of its highly favourable biochemical composition and greater availability, we conclude that microalgal production supports most animal production in freshwater ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Inferring past trends in lake water organic carbon concentrations in northern lakes using sediment spectroscopy.\n \n \n \n \n\n\n \n Meyer-Jacob, C.; Michelutti, N.; Paterson, A. M.; Monteith, D.; Yang, H.; Weckström, J.; Smol, J. P.; and Bindler, R.\n\n\n \n\n\n\n Environmental Science & Technology, 51(22): 13248–13255. November 2017.\n 00001\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{meyer-jacob_inferring_2017,\n\ttitle = {Inferring past trends in lake water organic carbon concentrations in northern lakes using sediment spectroscopy},\n\tvolume = {51},\n\tissn = {0013-936X},\n\turl = {http://dx.doi.org/10.1021/acs.est.7b03147},\n\tdoi = {10.1021/acs.est.7b03147},\n\tabstract = {Changing lake water total organic carbon (TOC) concentrations are of concern for lake management because of corresponding effects on aquatic ecosystem functioning, drinking water resources and carbon cycling between land and sea. Understanding the importance of human activities on TOC changes requires knowledge of past concentrations; however, water-monitoring data are typically only available for the past few decades, if at all. Here, we present a universal model to infer past lake water TOC concentrations in northern lakes across Europe and North America that uses visible-near-infrared (VNIR) spectroscopy on lake sediments. In the orthogonal partial least-squares model, VNIR spectra of surface-sediment samples are calibrated against corresponding surface water TOC concentrations (0.5–41 mg L–1) from 345 Arctic to northern temperate lakes in Canada, Greenland, Sweden and Finland. Internal model-cross-validation resulted in a R2 of 0.57 and a prediction error of 4.4 mg TOC L–1. First applications to lakes in southern Ontario and Scotland, which are outside of the model’s geographic range, show the model accurately captures monitoring trends, and suggests that TOC dynamics during the 20th century at these sites were primarily driven by changes in atmospheric deposition. Our results demonstrate that the lake water TOC model has multiregional applications and is not biased by postdepositional diagenesis, allowing the identification of past TOC variations in northern lakes of Europe and North America over time scales of decades to millennia.},\n\tnumber = {22},\n\turldate = {2017-11-21},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Meyer-Jacob, Carsten and Michelutti, Neal and Paterson, Andrew M. and Monteith, Don and Yang, Handong and Weckström, Jan and Smol, John P. and Bindler, Richard},\n\tmonth = nov,\n\tyear = {2017},\n\tnote = {00001},\n\tkeywords = {\\#nosource},\n\tpages = {13248--13255},\n}\n\n\n\n\n\n Changing lake water total organic carbon (TOC) concentrations are of concern for lake management because of corresponding effects on aquatic ecosystem functioning, drinking water resources and carbon cycling between land and sea. Understanding the importance of human activities on TOC changes requires knowledge of past concentrations; however, water-monitoring data are typically only available for the past few decades, if at all. Here, we present a universal model to infer past lake water TOC concentrations in northern lakes across Europe and North America that uses visible-near-infrared (VNIR) spectroscopy on lake sediments. In the orthogonal partial least-squares model, VNIR spectra of surface-sediment samples are calibrated against corresponding surface water TOC concentrations (0.5–41 mg L–1) from 345 Arctic to northern temperate lakes in Canada, Greenland, Sweden and Finland. Internal model-cross-validation resulted in a R2 of 0.57 and a prediction error of 4.4 mg TOC L–1. First applications to lakes in southern Ontario and Scotland, which are outside of the model’s geographic range, show the model accurately captures monitoring trends, and suggests that TOC dynamics during the 20th century at these sites were primarily driven by changes in atmospheric deposition. Our results demonstrate that the lake water TOC model has multiregional applications and is not biased by postdepositional diagenesis, allowing the identification of past TOC variations in northern lakes of Europe and North America over time scales of decades to millennia.\n
\n\n\n\n \n\n \n \n \n \n \n \n Genetic differences between willow warbler migratory phenotypes are few and cluster in large haplotype blocks.\n \n \n \n \n\n\n \n Lundberg, M.; Liedvogel, M.; Larson, K. W.; Sigeman, H.; Grahn, M.; Wright, A.; Åkesson, S.; and Bensch, S.\n\n\n \n\n\n\n Evolution Letters, 1(3): 155–168. August 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{lundberg_genetic_2017,\n\ttitle = {Genetic differences between willow warbler migratory phenotypes are few and cluster in large haplotype blocks},\n\tvolume = {1},\n\tissn = {2056-3744},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/evl3.15/abstract},\n\tdoi = {10.1002/evl3.15},\n\tabstract = {It is well established that differences in migratory behavior between populations of songbirds have a genetic basis but the actual genes underlying these traits remains largely unknown. In an attempt to identify such candidate genes we de novo assembled the genome of the willow warbler Phylloscopus trochilus, and used whole-genome resequencing and a SNP array to associate genomic variation with migratory phenotypes across two migratory divides around the Baltic Sea that separate SW migrating P. t. trochilus wintering in western Africa and SSE migrating P. t. acredula wintering in eastern and southern Africa. We found that the genomes of the two migratory phenotypes lack clear differences except for three highly differentiated regions located on chromosomes 1, 3, and 5 (containing 146, 135, and 53 genes, respectively). Within each migratory phenotype we found virtually no differences in allele frequencies for thousands of SNPs, even when comparing geographically distant populations breeding in Scandinavia and Far East Russia ({\\textgreater}6000 km). In each of the three differentiated regions, multidimensional scaling-based clustering of SNP genotypes from more than 1100 individuals demonstrates the presence of distinct haplotype clusters that are associated with each migratory phenotype. In turn, this suggests that recombination is absent or rare between haplotypes, which could be explained by inversion polymorphisms. Whereas SNP alleles on chromosome 3 correlate with breeding altitude and latitude, the allele distribution within the regions on chromosomes 1 and 5 perfectly matches the geographical distribution of the migratory phenotypes. The most differentiated 10 kb windows and missense mutations within these differentiated regions are associated with genes involved in fatty acid synthesis, possibly representing physiological adaptations to the different migratory strategies. The ∼200 genes in these regions, of which several lack described function, will direct future experimental and comparative studies in the search for genes that underlie important migratory traits.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-09-11},\n\tjournal = {Evolution Letters},\n\tauthor = {Lundberg, Max and Liedvogel, Miriam and Larson, Keith W. and Sigeman, Hanna and Grahn, Mats and Wright, Anthony and Åkesson, Susanne and Bensch, Staffan},\n\tmonth = aug,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Divergent chromosome region, local adaptation, migration},\n\tpages = {155--168},\n}\n\n\n\n\n\n It is well established that differences in migratory behavior between populations of songbirds have a genetic basis but the actual genes underlying these traits remains largely unknown. In an attempt to identify such candidate genes we de novo assembled the genome of the willow warbler Phylloscopus trochilus, and used whole-genome resequencing and a SNP array to associate genomic variation with migratory phenotypes across two migratory divides around the Baltic Sea that separate SW migrating P. t. trochilus wintering in western Africa and SSE migrating P. t. acredula wintering in eastern and southern Africa. We found that the genomes of the two migratory phenotypes lack clear differences except for three highly differentiated regions located on chromosomes 1, 3, and 5 (containing 146, 135, and 53 genes, respectively). Within each migratory phenotype we found virtually no differences in allele frequencies for thousands of SNPs, even when comparing geographically distant populations breeding in Scandinavia and Far East Russia (\\textgreater6000 km). In each of the three differentiated regions, multidimensional scaling-based clustering of SNP genotypes from more than 1100 individuals demonstrates the presence of distinct haplotype clusters that are associated with each migratory phenotype. In turn, this suggests that recombination is absent or rare between haplotypes, which could be explained by inversion polymorphisms. Whereas SNP alleles on chromosome 3 correlate with breeding altitude and latitude, the allele distribution within the regions on chromosomes 1 and 5 perfectly matches the geographical distribution of the migratory phenotypes. The most differentiated 10 kb windows and missense mutations within these differentiated regions are associated with genes involved in fatty acid synthesis, possibly representing physiological adaptations to the different migratory strategies. The ∼200 genes in these regions, of which several lack described function, will direct future experimental and comparative studies in the search for genes that underlie important migratory traits.\n
\n\n\n\n \n\n \n \n \n \n \n \n Shocks to fish production: Identification, trends, and consequences.\n \n \n \n \n\n\n \n Gephart, J. A.; Deutsch, L.; Pace, M. L.; Troell, M.; and Seekell, D. A.\n\n\n \n\n\n\n Global Environmental Change, 42: 24–32. January 2017.\n 00001\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{gephart_shocks_2017,\n\ttitle = {Shocks to fish production: {Identification}, trends, and consequences},\n\tvolume = {42},\n\tissn = {0959-3780},\n\tshorttitle = {Shocks to fish production},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0959378016304897},\n\tdoi = {10.1016/j.gloenvcha.2016.11.003},\n\tabstract = {Sudden disruptions, or shocks, to food production can adversely impact access to and trade of food commodities. Seafood is the most traded food commodity and is globally important to human nutrition. The seafood production and trade system is exposed to a variety of disruptions including fishery collapses, natural disasters, oil spills, policy changes, and aquaculture disease outbreaks, aquafeed resource access and price spikes. The patterns and trends of these shocks to fisheries and aquaculture are poorly characterized and this limits the ability to generalize or predict responses to political, economic, and environmental changes. We applied a statistical shock detection approach to historic fisheries and aquaculture data to identify shocks over the period 1976–2011. A complementary case study approach was used to identify possible key social and political dynamics related to these shocks. The lack of a trend in the frequency or magnitude of the identified shocks and the range of identified causes suggest shocks are a common feature of these systems which occur due to a variety, and often multiple and simultaneous, causes. Shocks occurred most frequently in the Caribbean and Central America, the Middle East and North Africa, and South America, while the largest magnitude shocks occurred in Asia, Europe, and Africa. Shocks also occurred more frequently in aquaculture systems than in capture systems, particularly in recent years. In response to shocks, countries tend to increase imports and experience decreases in supply. The specific combination of changes in trade and supply are context specific, which is highlighted through four case studies. Historical examples of shocks considered in this study can inform policy for responding to shocks and identify potential risks and opportunities to build resilience in the global food system.},\n\turldate = {2016-12-11},\n\tjournal = {Global Environmental Change},\n\tauthor = {Gephart, Jessica A. and Deutsch, Lisa and Pace, Michael L. and Troell, Max and Seekell, David A.},\n\tmonth = jan,\n\tyear = {2017},\n\tnote = {00001},\n\tkeywords = {\\#nosource, Fisheries, Food security, Food system, Shocks, resilience, trade},\n\tpages = {24--32},\n}\n\n\n\n\n\n Sudden disruptions, or shocks, to food production can adversely impact access to and trade of food commodities. Seafood is the most traded food commodity and is globally important to human nutrition. The seafood production and trade system is exposed to a variety of disruptions including fishery collapses, natural disasters, oil spills, policy changes, and aquaculture disease outbreaks, aquafeed resource access and price spikes. The patterns and trends of these shocks to fisheries and aquaculture are poorly characterized and this limits the ability to generalize or predict responses to political, economic, and environmental changes. We applied a statistical shock detection approach to historic fisheries and aquaculture data to identify shocks over the period 1976–2011. A complementary case study approach was used to identify possible key social and political dynamics related to these shocks. The lack of a trend in the frequency or magnitude of the identified shocks and the range of identified causes suggest shocks are a common feature of these systems which occur due to a variety, and often multiple and simultaneous, causes. Shocks occurred most frequently in the Caribbean and Central America, the Middle East and North Africa, and South America, while the largest magnitude shocks occurred in Asia, Europe, and Africa. Shocks also occurred more frequently in aquaculture systems than in capture systems, particularly in recent years. In response to shocks, countries tend to increase imports and experience decreases in supply. The specific combination of changes in trade and supply are context specific, which is highlighted through four case studies. Historical examples of shocks considered in this study can inform policy for responding to shocks and identify potential risks and opportunities to build resilience in the global food system.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of warming and increased nitrogen and sulfur deposition on boreal mire geochemistry.\n \n \n \n \n\n\n \n Olid, C.; Bindler, R.; Nilsson, M. B.; Eriksson, T.; and Klaminder, J.\n\n\n \n\n\n\n Applied Geochemistry, 78: 149–157. March 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{olid_effects_2017,\n\ttitle = {Effects of warming and increased nitrogen and sulfur deposition on boreal mire geochemistry},\n\tvolume = {78},\n\tissn = {0883-2927},\n\turl = {http://www.sciencedirect.com/science/article/pii/S088329271630230X},\n\tdoi = {10.1016/j.apgeochem.2016.12.015},\n\tabstract = {Boreal mire ecosystems are predicted to experience warmer air temperatures as well as changed deposition loads of nitrogen and sulfur during the coming century. In this study, we hypothesized that vegetation changes that accompany these new environmental conditions alter the chemical composition of peat. To test this hypothesis, we quantified changes in peat geochemistry (Al, Ca, Fe, Mg, Na, P, Pb, and Zn) that have occurred in field manipulation plots exposed to 12 years of warming and nitrogen and sulfur additions in a nutrient-poor boreal mire. In contrast to non-nutrients with a mainly atmospheric origin (i.e. Pb), Al-normalized inventories of micronutrients (Zn and Fe) and macronutrients (P and Ca) were significantly (P \\< 0.05) higher as a result of warming. For P and Ca, enrichments were also induced by nitrogen additions alone. These results suggest that mires evolving under increasing temperatures and availability of nitrogen are around two times more effective in storing nutrients in the accumulating peat. Our study provides the first empirical evidence that predicted changes in climate and nitrogen deposition scenarios will increase the retention of Ca, Fe, P, and Zn in surface peat of boreal mires in the near future, which may cause a depletion of nutrients released to inland waters dependent on mire inputs.},\n\turldate = {2017-04-28},\n\tjournal = {Applied Geochemistry},\n\tauthor = {Olid, Carolina and Bindler, Richard and Nilsson, Mats B. and Eriksson, Tobias and Klaminder, Jonatan},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Mire, Nitrogen, Peat geochemistry, climate change, nutrients, temperature},\n\tpages = {149--157},\n}\n\n\n\n\n\n Boreal mire ecosystems are predicted to experience warmer air temperatures as well as changed deposition loads of nitrogen and sulfur during the coming century. In this study, we hypothesized that vegetation changes that accompany these new environmental conditions alter the chemical composition of peat. To test this hypothesis, we quantified changes in peat geochemistry (Al, Ca, Fe, Mg, Na, P, Pb, and Zn) that have occurred in field manipulation plots exposed to 12 years of warming and nitrogen and sulfur additions in a nutrient-poor boreal mire. In contrast to non-nutrients with a mainly atmospheric origin (i.e. Pb), Al-normalized inventories of micronutrients (Zn and Fe) and macronutrients (P and Ca) were significantly (P < 0.05) higher as a result of warming. For P and Ca, enrichments were also induced by nitrogen additions alone. These results suggest that mires evolving under increasing temperatures and availability of nitrogen are around two times more effective in storing nutrients in the accumulating peat. Our study provides the first empirical evidence that predicted changes in climate and nitrogen deposition scenarios will increase the retention of Ca, Fe, P, and Zn in surface peat of boreal mires in the near future, which may cause a depletion of nutrients released to inland waters dependent on mire inputs.\n
\n\n\n\n \n\n \n \n \n \n \n \n Terrestrial support of lake food webs: Synthesis reveals controls over cross-ecosystem resource use.\n \n \n \n \n\n\n \n Tanentzap, A. J.; Kielstra, B. W.; Wilkinson, G. M.; Berggren, M.; Craig, N.; Giorgio, P. A. d.; Grey, J.; Gunn, J. M.; Jones, S. E.; Karlsson, J.; Solomon, C. T.; and Pace, M. L.\n\n\n \n\n\n\n Science Advances, 3(3): e1601765. March 2017.\n 00001\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{tanentzap_terrestrial_2017,\n\ttitle = {Terrestrial support of lake food webs: {Synthesis} reveals controls over cross-ecosystem resource use},\n\tvolume = {3},\n\tcopyright = {Copyright © 2017, The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.},\n\tissn = {2375-2548},\n\tshorttitle = {Terrestrial support of lake food webs},\n\turl = {http://advances.sciencemag.org/content/3/3/e1601765},\n\tdoi = {10.1126/sciadv.1601765},\n\tabstract = {Widespread evidence that organic matter exported from terrestrial into aquatic ecosystems supports recipient food webs remains controversial. A pressing question is not only whether high terrestrial support is possible but also what the general conditions are under which it arises. We assemble the largest data set, to date, of the isotopic composition (δ2H, δ13C, and δ15N) of lake zooplankton and the resources at the base of their associated food webs. In total, our data set spans 559 observations across 147 lakes from the boreal to subtropics. By predicting terrestrial resource support from within-lake and catchment-level characteristics, we found that half of all consumer observations that is, the median were composed of at least 42\\% terrestrially derived material. In general, terrestrial support of zooplankton was greatest in lakes with large physical and hydrological connections to catchments that were rich in aboveground and belowground organic matter. However, some consumers responded less strongly to terrestrial resources where within-lake production was elevated. Our study shows that multiple mechanisms drive widespread cross-ecosystem support of aquatic consumers across Northern Hemisphere lakes and suggests that changes in terrestrial landscapes will influence ecosystem processes well beyond their boundaries.\nThere is widespread evidence that aquatic consumers use terrestrial resources depending on the features of surrounding catchments.\nThere is widespread evidence that aquatic consumers use terrestrial resources depending on the features of surrounding catchments.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-05-11},\n\tjournal = {Science Advances},\n\tauthor = {Tanentzap, Andrew J. and Kielstra, Brian W. and Wilkinson, Grace M. and Berggren, Martin and Craig, Nicola and Giorgio, Paul A. del and Grey, Jonathan and Gunn, John M. and Jones, Stuart E. and Karlsson, Jan and Solomon, Christopher T. and Pace, Michael L.},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {00001},\n\tkeywords = {\\#nosource, food webs},\n\tpages = {e1601765},\n}\n\n\n\n\n\n Widespread evidence that organic matter exported from terrestrial into aquatic ecosystems supports recipient food webs remains controversial. A pressing question is not only whether high terrestrial support is possible but also what the general conditions are under which it arises. We assemble the largest data set, to date, of the isotopic composition (δ2H, δ13C, and δ15N) of lake zooplankton and the resources at the base of their associated food webs. In total, our data set spans 559 observations across 147 lakes from the boreal to subtropics. By predicting terrestrial resource support from within-lake and catchment-level characteristics, we found that half of all consumer observations that is, the median were composed of at least 42% terrestrially derived material. In general, terrestrial support of zooplankton was greatest in lakes with large physical and hydrological connections to catchments that were rich in aboveground and belowground organic matter. However, some consumers responded less strongly to terrestrial resources where within-lake production was elevated. Our study shows that multiple mechanisms drive widespread cross-ecosystem support of aquatic consumers across Northern Hemisphere lakes and suggests that changes in terrestrial landscapes will influence ecosystem processes well beyond their boundaries. There is widespread evidence that aquatic consumers use terrestrial resources depending on the features of surrounding catchments. There is widespread evidence that aquatic consumers use terrestrial resources depending on the features of surrounding catchments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Bryophyte traits explain climate-warming effects on tree seedling establishment.\n \n \n \n \n\n\n \n Lett, S.; Nilsson, M.; Wardle, D. A.; and Dorrepaal, E.\n\n\n \n\n\n\n Journal of Ecology, 105(2): 496–506. March 2017.\n 00001\n\n\n\n
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\n\n\n@article{lett_bryophyte_2017,\n\ttitle = {Bryophyte traits explain climate-warming effects on tree seedling establishment},\n\tvolume = {105},\n\tissn = {1365-2745},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/1365-2745.12688/abstract},\n\tdoi = {10.1111/1365-2745.12688},\n\tabstract = {* Above the alpine tree line, bryophytes cover much of the tundra soil surface in dense, often monospecific carpets. Therefore, when climate warming enables tree seedling establishment above the tree line, interaction with the bryophyte layer is inevitable. Bryophytes are known to modify their environment in various ways. However, little is known about to which extent and by which mechanisms bryophytes affect the response of tree seedlings to climate warming.\n\n\n* We aimed to assess and understand the importance of bryophyte species identity and traits for tree seedling performance at tree line temperatures and their response to warmer conditions. Seedlings of two common, tree line-forming tree species (Betula pubescens and Pinus sylvestris) were planted into intact cushions of eight common tundra bryophyte species and bryophyte-free soil and grown for 18 weeks at current (7·0 °C) and near-future (30–50 years; 9·2 °C) tree line average growing-season temperatures. Seedling performance (biomass increase and N-uptake) was measured and related to bryophyte species identity and traits indicative of their impact on the environment.\n\n\n* Tree seedlings performed equally well or better in the presence of bryophytes than in bryophyte-free soil, which contrasts to their usually negative effects in milder climates. In addition, seedling performance and their response to higher temperatures depended on bryophyte species and seedlings of both species grew largest in the pan-boreal and subarctic bryophyte Hylocomium splendens. However, B. pubescens seedlings showed much stronger responses to higher temperatures when grown in bryophytes than in bryophyte-free soil, while the opposite was true for P. sylvestris seedlings. For B. pubescens, but not for P. sylvestris, available organic nitrogen of the bryophyte species was the trait that best predicted seedling responses to higher temperatures, likely because these seedlings had increased N-demands.\n\n\n* Synthesis. Climatically driven changes in bryophyte species distribution may not only have knock-on effects on vascular plant establishment, but temperature effects on seedling performance are themselves moderated by bryophytes in a species-specific way. Bryophyte traits can serve as a useful tool for understanding and predicting these complex interactions.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-09-11},\n\tjournal = {Journal of Ecology},\n\tauthor = {Lett, Signe and Nilsson, Marie-Charlotte and Wardle, David A. and Dorrepaal, Ellen},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {00001},\n\tkeywords = {\\#nosource, Betula pubescens, Hylocomium splendens, Nitrogen, Pinus sylvestris, bryophyte density, effect traits, mosses, phenols, seedling growth, water retention capacity},\n\tpages = {496--506},\n}\n\n\n\n\n\n * Above the alpine tree line, bryophytes cover much of the tundra soil surface in dense, often monospecific carpets. Therefore, when climate warming enables tree seedling establishment above the tree line, interaction with the bryophyte layer is inevitable. Bryophytes are known to modify their environment in various ways. However, little is known about to which extent and by which mechanisms bryophytes affect the response of tree seedlings to climate warming. * We aimed to assess and understand the importance of bryophyte species identity and traits for tree seedling performance at tree line temperatures and their response to warmer conditions. Seedlings of two common, tree line-forming tree species (Betula pubescens and Pinus sylvestris) were planted into intact cushions of eight common tundra bryophyte species and bryophyte-free soil and grown for 18 weeks at current (7·0 °C) and near-future (30–50 years; 9·2 °C) tree line average growing-season temperatures. Seedling performance (biomass increase and N-uptake) was measured and related to bryophyte species identity and traits indicative of their impact on the environment. * Tree seedlings performed equally well or better in the presence of bryophytes than in bryophyte-free soil, which contrasts to their usually negative effects in milder climates. In addition, seedling performance and their response to higher temperatures depended on bryophyte species and seedlings of both species grew largest in the pan-boreal and subarctic bryophyte Hylocomium splendens. However, B. pubescens seedlings showed much stronger responses to higher temperatures when grown in bryophytes than in bryophyte-free soil, while the opposite was true for P. sylvestris seedlings. For B. pubescens, but not for P. sylvestris, available organic nitrogen of the bryophyte species was the trait that best predicted seedling responses to higher temperatures, likely because these seedlings had increased N-demands. * Synthesis. Climatically driven changes in bryophyte species distribution may not only have knock-on effects on vascular plant establishment, but temperature effects on seedling performance are themselves moderated by bryophytes in a species-specific way. Bryophyte traits can serve as a useful tool for understanding and predicting these complex interactions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Brownification increases winter mortality in fish.\n \n \n \n \n\n\n \n Hedström, P.; Bystedt, D.; Karlsson, J.; Bokma, F.; and Byström, P.\n\n\n \n\n\n\n Oecologia, 183(2): 587–595. February 2017.\n 00002\n\n\n\n
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\n\n\n@article{hedstrom_brownification_2017,\n\ttitle = {Brownification increases winter mortality in fish},\n\tvolume = {183},\n\tissn = {0029-8549, 1432-1939},\n\turl = {https://link.springer.com/article/10.1007/s00442-016-3779-y},\n\tdoi = {10.1007/s00442-016-3779-y},\n\tabstract = {In northern climates, winter is a bottleneck for many organisms. Low light and resource availability constrains individual foraging rates, potentially leading to starvation and increased mortality. Increasing input of humic substances to aquatic ecosystems causes brownification of water and hence a further decrease of light availability, which may lead to further decreased foraging rates and starvation mortality during winter. To test this hypothesis, we measured the effects of experimentally increased humic water input on consumption and survival of young-of-the-year three-spined stickleback (Gasterosteus aculeatus) over winter in large outdoor enclosures. Population densities were estimated in autumn, and the following spring and food availability and consumption were monitored over winter. As hypothesized, mortality was higher under humic (76\\%) as compared to ambient conditions (64\\%). In addition, body condition and ingested prey biomass were lower under humic conditions, even though resource availability was not lower under humic conditions. Light conditions were significantly poorer under humic conditions. This suggests that increased mortality and decreased body condition and ingested prey biomass were not due to decreased resource availability but due to decreased search efficiency in this visual feeding consumer. Increased future brownification of aquatic systems may, therefore, negatively affect both recruitment and densities of fish.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-09-11},\n\tjournal = {Oecologia},\n\tauthor = {Hedström, Per and Bystedt, David and Karlsson, Jan and Bokma, Folmer and Byström, Pär},\n\tmonth = feb,\n\tyear = {2017},\n\tnote = {00002},\n\tkeywords = {\\#nosource},\n\tpages = {587--595},\n}\n\n\n\n\n\n In northern climates, winter is a bottleneck for many organisms. Low light and resource availability constrains individual foraging rates, potentially leading to starvation and increased mortality. Increasing input of humic substances to aquatic ecosystems causes brownification of water and hence a further decrease of light availability, which may lead to further decreased foraging rates and starvation mortality during winter. To test this hypothesis, we measured the effects of experimentally increased humic water input on consumption and survival of young-of-the-year three-spined stickleback (Gasterosteus aculeatus) over winter in large outdoor enclosures. Population densities were estimated in autumn, and the following spring and food availability and consumption were monitored over winter. As hypothesized, mortality was higher under humic (76%) as compared to ambient conditions (64%). In addition, body condition and ingested prey biomass were lower under humic conditions, even though resource availability was not lower under humic conditions. Light conditions were significantly poorer under humic conditions. This suggests that increased mortality and decreased body condition and ingested prey biomass were not due to decreased resource availability but due to decreased search efficiency in this visual feeding consumer. Increased future brownification of aquatic systems may, therefore, negatively affect both recruitment and densities of fish.\n
\n\n\n\n \n\n \n \n \n \n \n \n Local adaptation along an environmental cline in a species with an inversion polymorphism.\n \n \n \n \n\n\n \n Wellenreuther, M.; Rosenquist, H.; Jaksons, P.; and Larson, K. W.\n\n\n \n\n\n\n Journal of Evolutionary Biology, 30(6): 1068–1077. June 2017.\n 00000\n\n\n\n
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\n\n\n@article{wellenreuther_local_2017,\n\ttitle = {Local adaptation along an environmental cline in a species with an inversion polymorphism},\n\tvolume = {30},\n\tissn = {1420-9101},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/jeb.13064/abstract},\n\tdoi = {10.1111/jeb.13064},\n\tabstract = {Polymorphic inversions are ubiquitous across the animal kingdom and are frequently associated with clines in inversion frequencies across environmental gradients. Such clines are thought to result from selection favouring local adaptation; however, empirical tests are scarce. The seaweed fly Coelopa frigida has an α/β inversion polymorphism, and previous work demonstrated that the α inversion frequency declines from the North Sea to the Baltic Sea and is correlated with changes in tidal range, salinity, algal composition and wrackbed stability. Here, we explicitly test the hypothesis that populations of C. frigida along this cline are locally adapted by conducting a reciprocal transplant experiment of four populations along this cline to quantify survival. We found that survival varied significantly across treatments and detected a significant Location x Substrate interaction, indicating local adaptation. Survival models showed that flies from locations at both extremes had highest survival on their native substrates, demonstrating that local adaptation is present at the extremes of the cline. Survival at the two intermediate locations was, however, not elevated at the native substrates, suggesting that gene flow in intermediate habitats may override selection. Together, our results support the notion that population extremes of species with polymorphic inversions are often locally adapted, even when spatially close, consistent with the growing view that inversions can have direct and strong effects on the fitness of species.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-09-11},\n\tjournal = {Journal of Evolutionary Biology},\n\tauthor = {Wellenreuther, M. and Rosenquist, H. and Jaksons, P. and Larson, Keith W.},\n\tmonth = jun,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Coelopa frigida, Environmental cline, Inversion, adaptation, polymorphism, survival},\n\tpages = {1068--1077},\n}\n\n\n\n\n\n Polymorphic inversions are ubiquitous across the animal kingdom and are frequently associated with clines in inversion frequencies across environmental gradients. Such clines are thought to result from selection favouring local adaptation; however, empirical tests are scarce. The seaweed fly Coelopa frigida has an α/β inversion polymorphism, and previous work demonstrated that the α inversion frequency declines from the North Sea to the Baltic Sea and is correlated with changes in tidal range, salinity, algal composition and wrackbed stability. Here, we explicitly test the hypothesis that populations of C. frigida along this cline are locally adapted by conducting a reciprocal transplant experiment of four populations along this cline to quantify survival. We found that survival varied significantly across treatments and detected a significant Location x Substrate interaction, indicating local adaptation. Survival models showed that flies from locations at both extremes had highest survival on their native substrates, demonstrating that local adaptation is present at the extremes of the cline. Survival at the two intermediate locations was, however, not elevated at the native substrates, suggesting that gene flow in intermediate habitats may override selection. Together, our results support the notion that population extremes of species with polymorphic inversions are often locally adapted, even when spatially close, consistent with the growing view that inversions can have direct and strong effects on the fitness of species.\n
\n\n\n\n \n\n \n \n \n \n \n \n Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers.\n \n \n \n \n\n\n \n Vorobyev, S. N.; Pokrovsky, O. S.; Serikova, S.; Manasypov, R. M.; Krickov, I. V.; Shirokova, L. S.; Lim, A.; Kolesnichenko, L. G.; Kirpotin, S. N.; and Karlsson, J.\n\n\n \n\n\n\n Water, 9(12): 985. December 2017.\n 00000\n\n\n\n
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\n\n\n@article{vorobyev_permafrost_2017,\n\ttitle = {Permafrost {Boundary} {Shift} in {Western} {Siberia} {May} {Not} {Modify} {Dissolved} {Nutrient} {Concentrations} in {Rivers}},\n\tvolume = {9},\n\tcopyright = {http://creativecommons.org/licenses/by/3.0/},\n\turl = {http://www.mdpi.com/2073-4441/9/12/985},\n\tdoi = {10.3390/w9120985},\n\tabstract = {Identifying the landscape and climate factors that control nutrient export by rivers in high latitude regions is one of the main challenges for understanding the Arctic Ocean response to ongoing climate change. This is especially true for Western Siberian rivers, which are responsible for a significant part of freshwater and solutes delivery to the Arctic Ocean and are draining vast permafrost-affected areas most vulnerable to thaw. Forty-nine small- and medium-sized rivers (10–100,000 km2) were sampled along a 1700 km long N–S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL) in June and August 2015. The N, P, dissolved organic and inorganic carbon (DOC and DIC, respectively), particular organic carbon (POC), Si, Ca, K, Fe, and Mn were analyzed to assess the role of environmental parameters, such as temperature, runoff, latitude, permafrost, bogs, lake, and forest coverage on nutrient concentration. The size of the watershed had no influence on nutrient concentrations in the rivers. Bogs and lakes retained nutrients whereas forests supplied P, Si, K, Ca, DIC, and Mn to rivers. The river water temperature was negatively correlated with Si and positively correlated with Fe in permafrost-free rivers. In permafrost-bearing rivers, the decrease in T northward was coupled with significant increases in PO4, Ptot, NH4, pH, DIC, Si, Ca, and Mn. North of the permafrost boundary (61° N), there was no difference in nutrient concentrations among permafrost zones (isolated, sporadic, discontinuous, and continuous). The climate warming in Western Siberia may lead to a permafrost boundary shift northward. Using a substituting space for time scenario, this may decrease or maintain the current levels of N, P, Si, K, Ca, DIC, and DOC concentrations in rivers of continuous permafrost zones compared to the present state. As a result, the export flux of nutrients by the small- and medium-sized rivers of the Western Siberian subarctic to the Arctic Ocean coastal zone may remain constant, or even decrease.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2018-01-02},\n\tjournal = {Water},\n\tauthor = {Vorobyev, Sergey N. and Pokrovsky, Oleg S. and Serikova, Svetlana and Manasypov, Rinat M. and Krickov, Ivan V. and Shirokova, Liudmila S. and Lim, Artem and Kolesnichenko, Larisa G. and Kirpotin, Sergey N. and Karlsson, Jan},\n\tmonth = dec,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Siberia, ammonium, nitrate, permafrost, phosphate, phosphorus, river},\n\tpages = {985},\n}\n\n\n\n\n\n Identifying the landscape and climate factors that control nutrient export by rivers in high latitude regions is one of the main challenges for understanding the Arctic Ocean response to ongoing climate change. This is especially true for Western Siberian rivers, which are responsible for a significant part of freshwater and solutes delivery to the Arctic Ocean and are draining vast permafrost-affected areas most vulnerable to thaw. Forty-nine small- and medium-sized rivers (10–100,000 km2) were sampled along a 1700 km long N–S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL) in June and August 2015. The N, P, dissolved organic and inorganic carbon (DOC and DIC, respectively), particular organic carbon (POC), Si, Ca, K, Fe, and Mn were analyzed to assess the role of environmental parameters, such as temperature, runoff, latitude, permafrost, bogs, lake, and forest coverage on nutrient concentration. The size of the watershed had no influence on nutrient concentrations in the rivers. Bogs and lakes retained nutrients whereas forests supplied P, Si, K, Ca, DIC, and Mn to rivers. The river water temperature was negatively correlated with Si and positively correlated with Fe in permafrost-free rivers. In permafrost-bearing rivers, the decrease in T northward was coupled with significant increases in PO4, Ptot, NH4, pH, DIC, Si, Ca, and Mn. North of the permafrost boundary (61° N), there was no difference in nutrient concentrations among permafrost zones (isolated, sporadic, discontinuous, and continuous). The climate warming in Western Siberia may lead to a permafrost boundary shift northward. Using a substituting space for time scenario, this may decrease or maintain the current levels of N, P, Si, K, Ca, DIC, and DOC concentrations in rivers of continuous permafrost zones compared to the present state. As a result, the export flux of nutrients by the small- and medium-sized rivers of the Western Siberian subarctic to the Arctic Ocean coastal zone may remain constant, or even decrease.\n
\n\n\n\n \n\n \n \n \n \n \n \n Towards the co-ordination of terrestrial ecosystem protocols across European research infrastructures.\n \n \n \n \n\n\n \n Firbank, L. G.; Bertora, C.; Blankman, D.; Delle Vedove, G.; Frenzel, M.; Grignani, C.; Groner, E.; Kertész, M.; Krab, E. J.; Matteucci, G.; Menta, C.; Mueller, C. W.; Stadler, J.; and Kunin, W. E.\n\n\n \n\n\n\n Ecology and Evolution, 7(11): 3967–3975. June 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{firbank_towards_2017,\n\ttitle = {Towards the co-ordination of terrestrial ecosystem protocols across {European} research infrastructures},\n\tvolume = {7},\n\tissn = {2045-7758},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/ece3.2997/abstract},\n\tdoi = {10.1002/ece3.2997},\n\tabstract = {The study of ecosystem processes over multiple scales of space and time is often best achieved using comparable data from multiple sites. Yet, long-term ecological observatories have often developed their own data collection protocols. Here, we address this problem by proposing a set of ecological protocols suitable for widespread adoption by the ecological community. Scientists from the European ecological research community prioritized terrestrial ecosystem parameters that could benefit from a more consistent approach to data collection within the resources available at most long-term ecological observatories. Parameters for which standard methods are in widespread use, or for which methods are evolving rapidly, were not selected. Protocols were developed by domain experts, building on existing methods where possible, and refined through a process of field testing and training. They address above-ground plant biomass; decomposition; land use and management; leaf area index; soil mesofaunal diversity; soil C and N stocks, and greenhouse gas emissions from soils. These complement existing methods to provide a complete assessment of ecological integrity. These protocols offer integrated approaches to ecological data collection that are low cost and are starting to be used across the European Long Term Ecological Research community.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2017-09-18},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Firbank, Les G. and Bertora, Chiara and Blankman, David and Delle Vedove, Gemini and Frenzel, Mark and Grignani, Carlo and Groner, Elli and Kertész, Miklós and Krab, Eveline J. and Matteucci, Giorgio and Menta, Christina and Mueller, Carsten W. and Stadler, Jutta and Kunin, William E.},\n\tmonth = jun,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, biogeochemical cycles, ecological Integrity, ecological processes, long term ecological research, quality assurance of ecological data},\n\tpages = {3967--3975},\n}\n\n\n\n\n\n The study of ecosystem processes over multiple scales of space and time is often best achieved using comparable data from multiple sites. Yet, long-term ecological observatories have often developed their own data collection protocols. Here, we address this problem by proposing a set of ecological protocols suitable for widespread adoption by the ecological community. Scientists from the European ecological research community prioritized terrestrial ecosystem parameters that could benefit from a more consistent approach to data collection within the resources available at most long-term ecological observatories. Parameters for which standard methods are in widespread use, or for which methods are evolving rapidly, were not selected. Protocols were developed by domain experts, building on existing methods where possible, and refined through a process of field testing and training. They address above-ground plant biomass; decomposition; land use and management; leaf area index; soil mesofaunal diversity; soil C and N stocks, and greenhouse gas emissions from soils. These complement existing methods to provide a complete assessment of ecological integrity. These protocols offer integrated approaches to ecological data collection that are low cost and are starting to be used across the European Long Term Ecological Research community.\n
\n\n\n\n \n\n \n \n \n \n \n \n Environmental relevant levels of a benzodiazepine (oxazepam) alters important behavioral traits in a common planktivorous fish, (Rutilus rutilus).\n \n \n \n \n\n\n \n Brodin, T.; Nordling, J.; Lagesson, A.; Klaminder, J.; Hellström, G.; Christensen, B.; and Fick, J.\n\n\n \n\n\n\n Journal of Toxicology and Environmental Health, Part A, 0(0): 1–8. August 2017.\n 00000 \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{brodin_environmental_2017,\n\ttitle = {Environmental relevant levels of a benzodiazepine (oxazepam) alters important behavioral traits in a common planktivorous fish, ({Rutilus} rutilus)},\n\tvolume = {0},\n\tissn = {1528-7394},\n\turl = {http://dx.doi.org/10.1080/15287394.2017.1352214},\n\tdoi = {10.1080/15287394.2017.1352214},\n\tabstract = {Environmental pollution by pharmaceuticals is increasingly recognized as a major threat to aquatic ecosystems worldwide. A complex mix of pharmaceuticals enters waterways via treated wastewater effluent and many remain biochemically active after the drugs reach aquatic systems. However, to date little is known regarding the ecological effects that might arise following pharmaceutical contamination of aquatic environments. One group of particular concern is behaviorally modifying pharmaceuticals as seemingly minor changes in behavior may initiate marked ecological consequences. The aim of this study was to examine the influence of a benzodiazepine anxiolytic drug (oxazepam) on key behavioral traits in wild roach (Rutilus rutilus) at concentrations similar to those encountered in effluent surface waters. Roach exposed to water with high concentrations of oxazepam (280 µg/L) exhibited increased boldness, while roach at low treatment (0.84 µg/L) became bolder and more active compared to control fish. Our results reinforce the notion that anxiolytic drugs may be affecting fish behavior in natural systems, emphasizing the need for further research on ecological impacts of pharmaceuticals in aquatic systems and development of new tools to incorporate ecologically relevant behavioral endpoints into ecotoxicological risk assessment.},\n\tnumber = {0},\n\turldate = {2017-09-11},\n\tjournal = {Journal of Toxicology and Environmental Health, Part A},\n\tauthor = {Brodin, Tomas and Nordling, Johanna and Lagesson, Annelie and Klaminder, Jonatan and Hellström, Gustav and Christensen, Bent and Fick, Jerker},\n\tmonth = aug,\n\tyear = {2017},\n\tpmid = {28829722},\n\tnote = {00000 },\n\tkeywords = {\\#nosource},\n\tpages = {1--8},\n}\n\n\n\n\n\n Environmental pollution by pharmaceuticals is increasingly recognized as a major threat to aquatic ecosystems worldwide. A complex mix of pharmaceuticals enters waterways via treated wastewater effluent and many remain biochemically active after the drugs reach aquatic systems. However, to date little is known regarding the ecological effects that might arise following pharmaceutical contamination of aquatic environments. One group of particular concern is behaviorally modifying pharmaceuticals as seemingly minor changes in behavior may initiate marked ecological consequences. The aim of this study was to examine the influence of a benzodiazepine anxiolytic drug (oxazepam) on key behavioral traits in wild roach (Rutilus rutilus) at concentrations similar to those encountered in effluent surface waters. Roach exposed to water with high concentrations of oxazepam (280 µg/L) exhibited increased boldness, while roach at low treatment (0.84 µg/L) became bolder and more active compared to control fish. Our results reinforce the notion that anxiolytic drugs may be affecting fish behavior in natural systems, emphasizing the need for further research on ecological impacts of pharmaceuticals in aquatic systems and development of new tools to incorporate ecologically relevant behavioral endpoints into ecotoxicological risk assessment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Refining particle positions using circular symmetry.\n \n \n \n \n\n\n \n Rodriguez, A.; Zhang, H.; Wiklund, K.; Brodin, T.; Klaminder, J.; Andersson, P.; and Andersson, M.\n\n\n \n\n\n\n PLOS ONE, 12(4): e0175015. April 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{rodriguez_refining_2017,\n\ttitle = {Refining particle positions using circular symmetry},\n\tvolume = {12},\n\tissn = {1932-6203},\n\turl = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0175015},\n\tdoi = {10.1371/journal.pone.0175015},\n\tabstract = {Particle and object tracking is gaining attention in industrial applications and is commonly applied in: colloidal, biophysical, ecological, and micro-fluidic research. Reliable tracking information is heavily dependent on the system under study and algorithms that correctly determine particle position between images. However, in a real environmental context with the presence of noise including particular or dissolved matter in water, and low and fluctuating light conditions, many algorithms fail to obtain reliable information. We propose a new algorithm, the Circular Symmetry algorithm (C-Sym), for detecting the position of a circular particle with high accuracy and precision in noisy conditions. The algorithm takes advantage of the spatial symmetry of the particle allowing for subpixel accuracy. We compare the proposed algorithm with four different methods using both synthetic and experimental datasets. The results show that C-Sym is the most accurate and precise algorithm when tracking micro-particles in all tested conditions and it has the potential for use in applications including tracking biota in their environment.},\n\tnumber = {4},\n\turldate = {2017-09-11},\n\tjournal = {PLOS ONE},\n\tauthor = {Rodriguez, Alvaro and Zhang, Hanqing and Wiklund, Krister and Brodin, Tomas and Klaminder, Jonatan and Andersson, Patrik and Andersson, Magnus},\n\tmonth = apr,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Algorithms, Diffraction, Experimental design, Fluorescence imaging, Fluorescence microscopy, Interpolation, Polynomials, Symmetry},\n\tpages = {e0175015},\n}\n\n\n\n\n\n Particle and object tracking is gaining attention in industrial applications and is commonly applied in: colloidal, biophysical, ecological, and micro-fluidic research. Reliable tracking information is heavily dependent on the system under study and algorithms that correctly determine particle position between images. However, in a real environmental context with the presence of noise including particular or dissolved matter in water, and low and fluctuating light conditions, many algorithms fail to obtain reliable information. We propose a new algorithm, the Circular Symmetry algorithm (C-Sym), for detecting the position of a circular particle with high accuracy and precision in noisy conditions. The algorithm takes advantage of the spatial symmetry of the particle allowing for subpixel accuracy. We compare the proposed algorithm with four different methods using both synthetic and experimental datasets. The results show that C-Sym is the most accurate and precise algorithm when tracking micro-particles in all tested conditions and it has the potential for use in applications including tracking biota in their environment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Boreal Forests Sequester Large Amounts of Mercury over Millennial Time Scales in the Absence of Wildfire.\n \n \n \n \n\n\n \n Giesler, R.; Clemmensen, K. E.; Wardle, D. A.; Klaminder, J.; and Bindler, R.\n\n\n \n\n\n\n Environmental Science & Technology, 51(5): 2621–2627. March 2017.\n 00000\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{giesler_boreal_2017,\n\ttitle = {Boreal {Forests} {Sequester} {Large} {Amounts} of {Mercury} over {Millennial} {Time} {Scales} in the {Absence} of {Wildfire}},\n\tvolume = {51},\n\tissn = {0013-936X},\n\turl = {http://dx.doi.org/10.1021/acs.est.6b06369},\n\tdoi = {10.1021/acs.est.6b06369},\n\tabstract = {Alterations in fire activity due to climate change and fire suppression may have profound effects on the balance between storage and release of carbon (C) and associated volatile elements. Stored soil mercury (Hg) is known to volatilize due to wildfires and this could substantially affect the land-air exchange of Hg; conversely the absence of fires and human disturbance may increase the time period over which Hg is sequestered. Here we show for a wildfire chronosequence spanning over more than 5000 years in boreal forest in northern Sweden that belowground inventories of total Hg are strongly related to soil humus C accumulation (R2 = 0.94, p {\\textless} 0.001). Our data clearly show that northern boreal forest soils have a strong sink capacity for Hg, and indicate that the sequestered Hg is bound in soil organic matter pools accumulating over millennia. Our results also suggest that more than half of the Hg stock in the sites with the longest time since fire originates from deposition predating the onset of large-scale anthropogenic emissions. This study emphasizes the importance of boreal forest humus soils for Hg storage and reveals that this pool is likely to persist over millennial time scales in the prolonged absence of fire.},\n\tnumber = {5},\n\turldate = {2017-09-11},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Giesler, Reiner and Clemmensen, Karina E. and Wardle, David A. and Klaminder, Jonatan and Bindler, Richard},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {2621--2627},\n}\n\n\n\n\n\n Alterations in fire activity due to climate change and fire suppression may have profound effects on the balance between storage and release of carbon (C) and associated volatile elements. Stored soil mercury (Hg) is known to volatilize due to wildfires and this could substantially affect the land-air exchange of Hg; conversely the absence of fires and human disturbance may increase the time period over which Hg is sequestered. Here we show for a wildfire chronosequence spanning over more than 5000 years in boreal forest in northern Sweden that belowground inventories of total Hg are strongly related to soil humus C accumulation (R2 = 0.94, p \\textless 0.001). Our data clearly show that northern boreal forest soils have a strong sink capacity for Hg, and indicate that the sequestered Hg is bound in soil organic matter pools accumulating over millennia. Our results also suggest that more than half of the Hg stock in the sites with the longest time since fire originates from deposition predating the onset of large-scale anthropogenic emissions. This study emphasizes the importance of boreal forest humus soils for Hg storage and reveals that this pool is likely to persist over millennial time scales in the prolonged absence of fire.\n
\n\n\n\n \n\n \n \n \n \n \n \n Migratory Connectivity of North American Caspian Tern (Hydroprogne caspia) Populations.\n \n \n \n \n\n\n \n Craig, D. P.; and Larson, K. W.\n\n\n \n\n\n\n Waterbirds, 40(1): 58–62. March 2017.\n 00000\n\n\n\n
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\n\n\n\n@article{craig_migratory_2017,\n\ttitle = {Migratory {Connectivity} of {North} {American} {Caspian} {Tern} ({Hydroprogne} caspia) {Populations}},\n\tvolume = {40},\n\tissn = {1524-4695, 1938-5390},\n\turl = {http://www.bioone.org/doi/10.1675/063.040.0108},\n\tdoi = {10.1675/063.040.0108},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-03-22},\n\tjournal = {Waterbirds},\n\tauthor = {Craig, David P. and Larson, Keith W.},\n\tmonth = mar,\n\tyear = {2017},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {58--62},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Screening of benzodiazepines in thirty European rivers.\n \n \n \n \n\n\n \n Fick, J.; Brodin, T.; Heynen, M.; Klaminder, J.; Jonsson, M.; Grabicova, K.; Randak, T.; Grabic, R.; Kodes, V.; Slobodnik, J.; Sweetman, A.; Earnshaw, M.; Barra Caracciolo, A.; Lettieri, T.; and Loos, R.\n\n\n \n\n\n\n Chemosphere, 176: 324–332. June 2017.\n 00003\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{fick_screening_2017,\n\ttitle = {Screening of benzodiazepines in thirty {European} rivers},\n\tvolume = {176},\n\tissn = {0045-6535},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0045653517303156},\n\tdoi = {10.1016/j.chemosphere.2017.02.126},\n\tabstract = {Pharmaceuticals as environmental contaminants have received a lot of interest over the past decade but, for several pharmaceuticals, relatively little is known about their occurrence in European surface waters. Benzodiazepines, a class of pharmaceuticals with anxiolytic properties, have received interest due to their behavioral modifying effect on exposed biota. In this study, our results show the presence of one or more benzodiazepine(s) in 86\\% of the analyzed surface water samples (n = 138) from 30 rivers, representing seven larger European catchments. Of the 13 benzodiazepines included in the study, we detected 9, which together showed median and mean concentrations (of the results above limit of quantification) of 5.4 and 9.6 ng L−1, respectively. Four benzodiazepines (oxazepam, temazepam, clobazam, and bromazepam) were the most commonly detected. In particular, oxazepam had the highest frequency of detection (85\\%) and a maximum concentration of 61 ng L−1. Temazepam and clobazam were found in 26\\% (maximum concentration of 39 ng L−1) and 14\\% (maximum concentration of 11 ng L−1) of the samples analyzed, respectively. Finally, bromazepam was found only in Germany and in 16 out of total 138 samples (12\\%), with a maximum concentration of 320 ng L−1. This study clearly shows that benzodiazepines are common micro-contaminants of the largest European river systems at ng L−1 levels. Although these concentrations are more than a magnitude lower than those reported to have effective effects on exposed biota, environmental effects cannot be excluded considering the possibility of additive and sub-lethal effects.},\n\turldate = {2017-03-06},\n\tjournal = {Chemosphere},\n\tauthor = {Fick, Jerker and Brodin, Tomas and Heynen, Martina and Klaminder, Jonatan and Jonsson, Micael and Grabicova, Katerina and Randak, Tomas and Grabic, Roman and Kodes, Vit and Slobodnik, Jaroslav and Sweetman, Andrew and Earnshaw, Mark and Barra Caracciolo, Anna and Lettieri, Teresa and Loos, Robert},\n\tmonth = jun,\n\tyear = {2017},\n\tnote = {00003},\n\tkeywords = {\\#nosource, Anxiolytics, Bromazepam, Clobazam, Oxazepam, Temazepam},\n\tpages = {324--332},\n}\n\n\n\n\n\n Pharmaceuticals as environmental contaminants have received a lot of interest over the past decade but, for several pharmaceuticals, relatively little is known about their occurrence in European surface waters. Benzodiazepines, a class of pharmaceuticals with anxiolytic properties, have received interest due to their behavioral modifying effect on exposed biota. In this study, our results show the presence of one or more benzodiazepine(s) in 86% of the analyzed surface water samples (n = 138) from 30 rivers, representing seven larger European catchments. Of the 13 benzodiazepines included in the study, we detected 9, which together showed median and mean concentrations (of the results above limit of quantification) of 5.4 and 9.6 ng L−1, respectively. Four benzodiazepines (oxazepam, temazepam, clobazam, and bromazepam) were the most commonly detected. In particular, oxazepam had the highest frequency of detection (85%) and a maximum concentration of 61 ng L−1. Temazepam and clobazam were found in 26% (maximum concentration of 39 ng L−1) and 14% (maximum concentration of 11 ng L−1) of the samples analyzed, respectively. Finally, bromazepam was found only in Germany and in 16 out of total 138 samples (12%), with a maximum concentration of 320 ng L−1. This study clearly shows that benzodiazepines are common micro-contaminants of the largest European river systems at ng L−1 levels. Although these concentrations are more than a magnitude lower than those reported to have effective effects on exposed biota, environmental effects cannot be excluded considering the possibility of additive and sub-lethal effects.\n
\n\n\n\n \n\n \n \n \n \n \n \n Climate change reduces extent of temperate drylands and intensifies drought in deep soils.\n \n \n \n \n\n\n \n Schlaepfer, D. R.; Bradford, J. B.; Lauenroth, W. K.; Munson, S. M.; Tietjen, B.; Hall, S. A.; Wilson, S. D.; Duniway, M. C.; Jia, G.; Pyke, D. A.; Lkhagva, A.; and Jamiyansharav, K.\n\n\n \n\n\n\n Nature Communications, 8: 14196. January 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{schlaepfer_climate_2017,\n\ttitle = {Climate change reduces extent of temperate drylands and intensifies drought in deep soils},\n\tvolume = {8},\n\tcopyright = {© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.},\n\tissn = {2041-1723},\n\turl = {http://www.nature.com/ncomms/2017/170131/ncomms14196/full/ncomms14196.html},\n\tdoi = {10.1038/ncomms14196},\n\tabstract = {Future stress on water resources, and on temperate drylands in particular, remains uncertain. Here, the authors show that climate in the late twenty first century may reduce the extent of temperate drylands, dry deep soils, and create intra-regional and intercontinental differences in ecological drought.},\n\tlanguage = {en},\n\turldate = {2017-02-07},\n\tjournal = {Nature Communications},\n\tauthor = {Schlaepfer, Daniel R. and Bradford, John B. and Lauenroth, William K. and Munson, Seth M. and Tietjen, Britta and Hall, Sonia A. and Wilson, Scott D. and Duniway, Michael C. and Jia, Gensuo and Pyke, David A. and Lkhagva, Ariuntsetseg and Jamiyansharav, Khishigbayar},\n\tmonth = jan,\n\tyear = {2017},\n\tkeywords = {\\#nosource},\n\tpages = {14196},\n}\n\n\n\n\n\n Future stress on water resources, and on temperate drylands in particular, remains uncertain. Here, the authors show that climate in the late twenty first century may reduce the extent of temperate drylands, dry deep soils, and create intra-regional and intercontinental differences in ecological drought.\n
\n\n\n\n \n\n \n \n \n \n \n \n Herbivory and nutrient limitation protect warming tundra from lowland species’ invasion and diversity loss.\n \n \n \n \n\n\n \n Eskelinen, A.; Kaarlejärvi, E.; and Olofsson, J.\n\n\n \n\n\n\n Global Change Biology, 23(1): 245–255. 2017.\n \n\n\n\n
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\n\n\n@article{eskelinen_herbivory_2017,\n\ttitle = {Herbivory and nutrient limitation protect warming tundra from lowland species’ invasion and diversity loss},\n\tvolume = {23},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.13397/full},\n\tdoi = {10.1111/gcb.13397},\n\tabstract = {00000},\n\tnumber = {1},\n\turldate = {2017-02-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Eskelinen, Anu and Kaarlejärvi, Elina and Olofsson, Johan},\n\tyear = {2017},\n\tkeywords = {\\#nosource, abiotic resistance, biotic resistance, co-limitation, colimitation, community-weighted mean traits, establishment limitation, grazing, multiple interacting global changes, range shift},\n\tpages = {245--255},\n}\n\n\n\n\n\n 00000\n
\n\n\n\n \n\n \n \n \n \n \n \n Elevation alters ecosystem properties across temperate treelines globally.\n \n \n \n \n\n\n \n Mayor, J. R.; Sanders, N. J.; Classen, A. T.; Bardgett, R. D.; Clément, J.; Fajardo, A.; Lavorel, S.; Sundqvist, M. K.; Bahn, M.; Chisholm, C.; Cieraad, E.; Gedalof, Z.; Grigulis, K.; Kudo, G.; Oberski, D. L.; and Wardle, D. A.\n\n\n \n\n\n\n Nature, 542(7639): 91–95. February 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{mayor_elevation_2017,\n\ttitle = {Elevation alters ecosystem properties across temperate treelines globally},\n\tvolume = {542},\n\tcopyright = {© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.},\n\tissn = {0028-0836},\n\turl = {http://www.nature.com/nature/journal/v542/n7639/full/nature21027.html},\n\tdoi = {10.1038/nature21027},\n\tabstract = {Temperature is a primary driver of the distribution of biodiversity as well as of ecosystem boundaries. Declining temperature with increasing elevation in montane systems has long been recognized as a major factor shaping plant community biodiversity, metabolic processes, and ecosystem dynamics. Elevational gradients, as thermoclines, also enable prediction of long-term ecological responses to climate warming. One of the most striking manifestations of increasing elevation is the abrupt transitions from forest to treeless alpine tundra. However, whether there are globally consistent above- and belowground responses to these transitions remains an open question. To disentangle the direct and indirect effects of temperature on ecosystem properties, here we evaluate replicate treeline ecotones in seven temperate regions of the world. We find that declining temperatures with increasing elevation did not affect tree leaf nutrient concentrations, but did reduce ground-layer community-weighted plant nitrogen, leading to the strong stoichiometric convergence of ground-layer plant community nitrogen to phosphorus ratios across all regions. Further, elevation-driven changes in plant nutrients were associated with changes in soil organic matter content and quality (carbon to nitrogen ratios) and microbial properties. Combined, our identification of direct and indirect temperature controls over plant communities and soil properties in seven contrasting regions suggests that future warming may disrupt the functional properties of montane ecosystems, particularly where plant community reorganization outpaces treeline advance.},\n\tlanguage = {en},\n\tnumber = {7639},\n\turldate = {2017-02-10},\n\tjournal = {Nature},\n\tauthor = {Mayor, Jordan R. and Sanders, Nathan J. and Classen, Aimée T. and Bardgett, Richard D. and Clément, Jean-Christophe and Fajardo, Alex and Lavorel, Sandra and Sundqvist, Maja K. and Bahn, Michael and Chisholm, Chelsea and Cieraad, Ellen and Gedalof, Ze’ev and Grigulis, Karl and Kudo, Gaku and Oberski, Daniel L. and Wardle, David A.},\n\tmonth = feb,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Climate-change ecology, Ecosystem ecology, Element cycles},\n\tpages = {91--95},\n}\n\n\n\n\n\n Temperature is a primary driver of the distribution of biodiversity as well as of ecosystem boundaries. Declining temperature with increasing elevation in montane systems has long been recognized as a major factor shaping plant community biodiversity, metabolic processes, and ecosystem dynamics. Elevational gradients, as thermoclines, also enable prediction of long-term ecological responses to climate warming. One of the most striking manifestations of increasing elevation is the abrupt transitions from forest to treeless alpine tundra. However, whether there are globally consistent above- and belowground responses to these transitions remains an open question. To disentangle the direct and indirect effects of temperature on ecosystem properties, here we evaluate replicate treeline ecotones in seven temperate regions of the world. We find that declining temperatures with increasing elevation did not affect tree leaf nutrient concentrations, but did reduce ground-layer community-weighted plant nitrogen, leading to the strong stoichiometric convergence of ground-layer plant community nitrogen to phosphorus ratios across all regions. Further, elevation-driven changes in plant nutrients were associated with changes in soil organic matter content and quality (carbon to nitrogen ratios) and microbial properties. Combined, our identification of direct and indirect temperature controls over plant communities and soil properties in seven contrasting regions suggests that future warming may disrupt the functional properties of montane ecosystems, particularly where plant community reorganization outpaces treeline advance.\n
\n\n\n\n \n\n \n \n \n \n \n \n Regulation of soil organic matter decomposition in permafrost-affected Siberian tundra soils - Impact of oxygen availability, freezing and thawing, temperature, and labile organic matter.\n \n \n \n \n\n\n \n Walz, J.; Knoblauch, C.; Böhme, L.; and Pfeiffer, E.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 110: 34–43. July 2017.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{walz_regulation_2017,\n\ttitle = {Regulation of soil organic matter decomposition in permafrost-affected {Siberian} tundra soils - {Impact} of oxygen availability, freezing and thawing, temperature, and labile organic matter},\n\tvolume = {110},\n\tissn = {0038-0717},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0038071716302668},\n\tdoi = {10.1016/j.soilbio.2017.03.001},\n\tabstract = {The large amounts of soil organic matter (SOM) in permafrost-affected soils are prone to increased microbial decomposition in a warming climate. The environmental parameters regulating the production of carbon dioxide (CO2) and methane (CH4), however, are insufficiently understood to confidently predict the feedback of thawing permafrost to global warming. Therefore, the effects of oxygen availability, freezing and thawing, temperature, and labile organic matter (OM) additions on greenhouse gas production were studied in northeast Siberian polygonal tundra soils, including the seasonally thawed active layer and upper perennially frozen permafrost. Soils were incubated at constant temperatures of 1 °C, 4 °C, or 8 °C for up to 150 days. CO2 production in surface layers was three times higher than in the deeper soil. Under anaerobic conditions, SOM decomposition was 2–6 times lower than under aerobic conditions and more CO2 than CH4 was produced. CH4 contributed less than 2\\% to anaerobic decomposition in thawed permafrost but more than 20\\% in the active layer. A freeze-thaw cycle caused a short-lived pulse of CO2 production directly after re-thawing. Q10 values, calculated via the equal-carbon method, increased with soil depth from 3.4 ± 1.6 in surface layers to 6.1 ± 2.8 in the permafrost. The addition of plant-derived labile OM (13C-labelled Carex aquatilis leaves) resulted in an increase in SOM decomposition only in permafrost (positive priming). The current results indicate that the decomposition of permafrost SOM will be more strongly influenced by rising temperatures and the availability of labile OM than active layer material. The obtained data can be used to inform process-based models to improve simulations of greenhouse gas production potentials from thawing permafrost landscapes.},\n\tlanguage = {en},\n\turldate = {2020-06-10},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Walz, Josefine and Knoblauch, Christian and Böhme, Luisa and Pfeiffer, Eva-Maria},\n\tmonth = jul,\n\tyear = {2017},\n\tkeywords = {\\#nosource, Aerobic, Anaerobic, Incubation, Lena river delta, Permafrost carbon, Priming, Q},\n\tpages = {34--43},\n}\n\n\n\n\n\n The large amounts of soil organic matter (SOM) in permafrost-affected soils are prone to increased microbial decomposition in a warming climate. The environmental parameters regulating the production of carbon dioxide (CO2) and methane (CH4), however, are insufficiently understood to confidently predict the feedback of thawing permafrost to global warming. Therefore, the effects of oxygen availability, freezing and thawing, temperature, and labile organic matter (OM) additions on greenhouse gas production were studied in northeast Siberian polygonal tundra soils, including the seasonally thawed active layer and upper perennially frozen permafrost. Soils were incubated at constant temperatures of 1 °C, 4 °C, or 8 °C for up to 150 days. CO2 production in surface layers was three times higher than in the deeper soil. Under anaerobic conditions, SOM decomposition was 2–6 times lower than under aerobic conditions and more CO2 than CH4 was produced. CH4 contributed less than 2% to anaerobic decomposition in thawed permafrost but more than 20% in the active layer. A freeze-thaw cycle caused a short-lived pulse of CO2 production directly after re-thawing. Q10 values, calculated via the equal-carbon method, increased with soil depth from 3.4 ± 1.6 in surface layers to 6.1 ± 2.8 in the permafrost. The addition of plant-derived labile OM (13C-labelled Carex aquatilis leaves) resulted in an increase in SOM decomposition only in permafrost (positive priming). The current results indicate that the decomposition of permafrost SOM will be more strongly influenced by rising temperatures and the availability of labile OM than active layer material. The obtained data can be used to inform process-based models to improve simulations of greenhouse gas production potentials from thawing permafrost landscapes.\n
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\n \n \n\n \n \n \n \n \n \n Long-term experimentally deepened snow decreases growing-season respiration in a low- and high-arctic tundra ecosystem.\n \n \n \n \n\n\n \n Semenchuk, P. R.; Christiansen, C. T.; Grogan, P.; Elberling, B.; and Cooper, E. J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 121(5): 1236–1248. 2016.\n _eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2015JG003251\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{semenchuk_long-term_2016,\n\ttitle = {Long-term experimentally deepened snow decreases growing-season respiration in a low- and high-arctic tundra ecosystem},\n\tvolume = {121},\n\tcopyright = {©2016. American Geophysical Union. All Rights Reserved.},\n\tissn = {2169-8961},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2015JG003251},\n\tdoi = {10.1002/2015JG003251},\n\tabstract = {Tundra soils store large amounts of carbon (C) that could be released through enhanced ecosystem respiration (ER) as the arctic warms. Over time, this may change the quantity and quality of available soil C pools, which in-turn may feedback and regulate ER responses to climate warming. Therefore, short-term increases in ER rates due to experimental warming may not be sustained over longer periods, as observed in other studies. One important aspect, which is often overlooked, is how climatic changes affecting ER in one season may carry-over and determine ER in following seasons. Using snow fences, we increased snow depth and thereby winter soil temperatures in a high-arctic site in Svalbard (78°N) and a low-arctic site in the Northwest Territories, Canada (64°N), for 5 and 9 years, respectively. Deepened snow enhanced winter ER while having negligible effect on growing-season soil temperatures and soil moisture. Growing-season ER at the high-arctic site was not affected by the snow treatment after 2 years. However, surprisingly, the deepened snow treatments significantly reduced growing-season ER rates after 5 years at the high-arctic site and after 8–9 years at the low-arctic site. We speculate that the reduction in ER rates, that became apparent only after several years of experimental manipulation, may, at least in part, be due to prolonged depletion of labile C substrate as a result of warmer soils over multiple cold seasons. Long-term changes in winter climate may therefore significantly influence annual net C balance not just because of increased wintertime C loss but also because of “legacy” effects on ER rates during the following growing seasons.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Semenchuk, Philipp R. and Christiansen, Casper T. and Grogan, Paul and Elberling, Bo and Cooper, Elisabeth J.},\n\tyear = {2016},\n\tnote = {\\_eprint: https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2015JG003251},\n\tkeywords = {\\#nosource, Diel, seasonal, and annual cycles, Snow, Trace gases, carbon cycling, climate change, cold season, ecosystem respiration, snow fence, tundra, winter},\n\tpages = {1236--1248},\n}\n\n\n\n\n\n Tundra soils store large amounts of carbon (C) that could be released through enhanced ecosystem respiration (ER) as the arctic warms. Over time, this may change the quantity and quality of available soil C pools, which in-turn may feedback and regulate ER responses to climate warming. Therefore, short-term increases in ER rates due to experimental warming may not be sustained over longer periods, as observed in other studies. One important aspect, which is often overlooked, is how climatic changes affecting ER in one season may carry-over and determine ER in following seasons. Using snow fences, we increased snow depth and thereby winter soil temperatures in a high-arctic site in Svalbard (78°N) and a low-arctic site in the Northwest Territories, Canada (64°N), for 5 and 9 years, respectively. Deepened snow enhanced winter ER while having negligible effect on growing-season soil temperatures and soil moisture. Growing-season ER at the high-arctic site was not affected by the snow treatment after 2 years. However, surprisingly, the deepened snow treatments significantly reduced growing-season ER rates after 5 years at the high-arctic site and after 8–9 years at the low-arctic site. We speculate that the reduction in ER rates, that became apparent only after several years of experimental manipulation, may, at least in part, be due to prolonged depletion of labile C substrate as a result of warmer soils over multiple cold seasons. Long-term changes in winter climate may therefore significantly influence annual net C balance not just because of increased wintertime C loss but also because of “legacy” effects on ER rates during the following growing seasons.\n
\n\n\n\n \n\n \n \n \n \n \n \n Assessing resilience in long-term ecological data sets.\n \n \n \n \n\n\n \n Müller, F.; Bergmann, M.; Dannowski, R.; Dippner, J. W.; Gnauck, A.; Haase, P.; Jochimsen, M. C.; Kasprzak, P.; Kröncke, I.; Kümmerlin, R.; Küster, M.; Lischeid, G.; Meesenburg, H.; Merz, C.; Millat, G.; Müller, J.; Padisák, J.; Schimming, C. G.; Schubert, H.; Schult, M.; Selmeczy, G.; Shatwell, T.; Stoll, S.; Schwabe, M.; Soltwedel, T.; Straile, D.; and Theuerkauf, M.\n\n\n \n\n\n\n Ecological Indicators, 65: 10–43. June 2016.\n \n\n\n\n
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\n\n\n@article{muller_assessing_2016,\n\tseries = {The value of long-term ecosystem research ({LTER}): {Addressing} global change ecology using site-based data},\n\ttitle = {Assessing resilience in long-term ecological data sets},\n\tvolume = {65},\n\tissn = {1470-160X},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1470160X15006305},\n\tdoi = {10.1016/j.ecolind.2015.10.066},\n\tabstract = {In this paper the concept of resilience is discussed on the base of 13 case studies from the German branch of the International Long-Term Ecological Research Program. In the introduction the resilience approach is presented as one possibility to describe ecosystem dynamics. The relations with the concepts of adaptability and ecological integrity are discussed and the research questions are formulated. The focal research objectives are related to the conditions of resilient behaviour of ecosystems, the role of spatio-temporal scales, the differences between short- or long-term dynamics, the basic methodological requirements to exactly define resilience, the role of the reference state and indicators and the suitability of resilience as a management concept. The main part of the paper consists of 13 small case study descriptions, which demonstrate phase transitions and resilient dynamics of several terrestrial and aquatic ecosystems at different time scales. In the discussion, some problems arising from the interpretation of the time series are highlighted and discussed. The topics of discussion are the conceptual challenges of the resilience approach, methodological problems, the role of indicator selection, the complex interactions between different disturbances, the significance of time scales and a comparison of the case studies. The article ends with a conclusion which focuses on the demand to link resilience with adaptability, in order to support the long-term dynamics of ecosystem development.},\n\turldate = {2024-03-26},\n\tjournal = {Ecological Indicators},\n\tauthor = {Müller, F. and Bergmann, M. and Dannowski, R. and Dippner, J. W. and Gnauck, A. and Haase, P. and Jochimsen, Marc C. and Kasprzak, P. and Kröncke, I. and Kümmerlin, R. and Küster, M. and Lischeid, G. and Meesenburg, H. and Merz, C. and Millat, G. and Müller, J. and Padisák, J. and Schimming, C. G. and Schubert, H. and Schult, M. and Selmeczy, G. and Shatwell, T. and Stoll, S. and Schwabe, M. and Soltwedel, T. and Straile, D. and Theuerkauf, M.},\n\tmonth = jun,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Ecosystem resilience and adaptability, Indicator selection, LTER, Long-term ecological research, Spatio-temporal scales},\n\tpages = {10--43},\n}\n\n\n\n\n\n In this paper the concept of resilience is discussed on the base of 13 case studies from the German branch of the International Long-Term Ecological Research Program. In the introduction the resilience approach is presented as one possibility to describe ecosystem dynamics. The relations with the concepts of adaptability and ecological integrity are discussed and the research questions are formulated. The focal research objectives are related to the conditions of resilient behaviour of ecosystems, the role of spatio-temporal scales, the differences between short- or long-term dynamics, the basic methodological requirements to exactly define resilience, the role of the reference state and indicators and the suitability of resilience as a management concept. The main part of the paper consists of 13 small case study descriptions, which demonstrate phase transitions and resilient dynamics of several terrestrial and aquatic ecosystems at different time scales. In the discussion, some problems arising from the interpretation of the time series are highlighted and discussed. The topics of discussion are the conceptual challenges of the resilience approach, methodological problems, the role of indicator selection, the complex interactions between different disturbances, the significance of time scales and a comparison of the case studies. The article ends with a conclusion which focuses on the demand to link resilience with adaptability, in order to support the long-term dynamics of ecosystem development.\n
\n\n\n\n \n\n \n \n \n \n \n \n Drug-Induced Behavioral Changes: Using Laboratory Observations to Predict Field Observations.\n \n \n \n \n\n\n \n Klaminder, J.; Hellström, G.; Fahlman, J.; Jonsson, M.; Fick, J.; Lagesson, A.; Bergman, E.; and Brodin, T.\n\n\n \n\n\n\n Frontiers in Environmental Science, 4: 00081. 2016.\n 00005\n\n\n\n
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\n\n\n@article{klaminder_drug-induced_2016,\n\ttitle = {Drug-{Induced} {Behavioral} {Changes}: {Using} {Laboratory} {Observations} to {Predict} {Field} {Observations}},\n\tvolume = {4},\n\tissn = {2296-665X},\n\tshorttitle = {Drug-{Induced} {Behavioral} {Changes}},\n\turl = {http://journal.frontiersin.org/article/10.3389/fenvs.2016.00081/abstract},\n\tdoi = {10.3389/fenvs.2016.00081},\n\tabstract = {Behavioral assays constitute important research tools when assessing how fish respond to environmental change. However, it is unclear how behavioral modifications recorded in laboratory assays are expressed in natural ecosystems, a limitation that makes it difficult to evaluate the predictive power of laboratory-based measurements. In this study, we hypothesized that exposure to a benzodiazepine (i.e., oxazepam) increases boldness and activity in laboratory assays as well as in field assays – that is, laboratory results can be used to predict field results. Moreover, we expected the modified behavior to affect other important ecological measures such as habitat selection and home range. To test our hypothesis, we exposed European perch (Perca fluviatilis) to oxazepam and measured subsequent changes in behavioral trials both in laboratory assays and in a lake ecosystem populated with a predatory fish species, pike (Esox lucius). In the lake, the positions of both perch and pike were tracked every three minutes for a month using acoustic telemetry. In the laboratory assay, the oxazepam-exposed perch were bolder and more active than the non-exposed perch. In the lake assay, the oxazepam-exposed perch were also more bold and active, had a larger home range, and used pelagic habitats more than the non-exposed perch. We conclude that ecotoxicological behavioral assays are useful for predicting the effects of exposure in natural systems. However, although individual responses to exposure were similar in both the laboratory and field trials, effects were more obvious in the field study, mainly due to reduced variability in the behavior measures from the lake. Hence, short-term behavioral assays may fail to detect all the effects expressed in natural environments. Nevertheless, our study clearly demonstrates that behavior modifications observed in laboratory settings can be used to predict how fish perform in aquatic ecosystems.},\n\tlanguage = {English},\n\turldate = {2017-01-03},\n\tjournal = {Frontiers in Environmental Science},\n\tauthor = {Klaminder, Jonatan and Hellström, Gustav and Fahlman, Johan and Jonsson, Micael and Fick, Jerker and Lagesson, Annelie and Bergman, Eva and Brodin, Tomas},\n\tyear = {2016},\n\tnote = {00005},\n\tkeywords = {\\#nosource, Anxiety, Field manipulation, GABAergic, Landscape of fear, behaviour},\n\tpages = {00081},\n}\n\n\n\n\n\n Behavioral assays constitute important research tools when assessing how fish respond to environmental change. However, it is unclear how behavioral modifications recorded in laboratory assays are expressed in natural ecosystems, a limitation that makes it difficult to evaluate the predictive power of laboratory-based measurements. In this study, we hypothesized that exposure to a benzodiazepine (i.e., oxazepam) increases boldness and activity in laboratory assays as well as in field assays – that is, laboratory results can be used to predict field results. Moreover, we expected the modified behavior to affect other important ecological measures such as habitat selection and home range. To test our hypothesis, we exposed European perch (Perca fluviatilis) to oxazepam and measured subsequent changes in behavioral trials both in laboratory assays and in a lake ecosystem populated with a predatory fish species, pike (Esox lucius). In the lake, the positions of both perch and pike were tracked every three minutes for a month using acoustic telemetry. In the laboratory assay, the oxazepam-exposed perch were bolder and more active than the non-exposed perch. In the lake assay, the oxazepam-exposed perch were also more bold and active, had a larger home range, and used pelagic habitats more than the non-exposed perch. We conclude that ecotoxicological behavioral assays are useful for predicting the effects of exposure in natural systems. However, although individual responses to exposure were similar in both the laboratory and field trials, effects were more obvious in the field study, mainly due to reduced variability in the behavior measures from the lake. Hence, short-term behavioral assays may fail to detect all the effects expressed in natural environments. Nevertheless, our study clearly demonstrates that behavior modifications observed in laboratory settings can be used to predict how fish perform in aquatic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n The size-distribution of Earth’s lakes.\n \n \n \n \n\n\n \n Cael, B. B.; and Seekell, D. A.\n\n\n \n\n\n\n Scientific Reports, 6: 29633. July 2016.\n \n\n\n\n
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\n\n\n@article{cael_size-distribution_2016,\n\ttitle = {The size-distribution of {Earth}’s lakes},\n\tvolume = {6},\n\tissn = {2045-2322},\n\turl = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4937396/},\n\tdoi = {10.1038/srep29633},\n\tabstract = {Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km2 are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes {\\textless}8.5 km2 are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.},\n\turldate = {2024-03-26},\n\tjournal = {Scientific Reports},\n\tauthor = {Cael, B. B. and Seekell, D. A.},\n\tmonth = jul,\n\tyear = {2016},\n\tpmid = {27388607},\n\tpmcid = {PMC4937396},\n\tkeywords = {\\#nosource},\n\tpages = {29633},\n}\n\n\n\n\n\n Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km2 are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes \\textless8.5 km2 are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.\n
\n\n\n\n \n\n \n \n \n \n \n \n The hidden season: growing season is 50% longer below than above ground along an arctic elevation gradient.\n \n \n \n \n\n\n \n Blume-Werry, G.; Wilson, S. D.; Kreyling, J.; and Milbau, A.\n\n\n \n\n\n\n New Phytologist, 209(3): 978–986. February 2016.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{blume-werry_hidden_2016,\n\ttitle = {The hidden season: growing season is 50\\% longer below than above ground along an arctic elevation gradient},\n\tvolume = {209},\n\tissn = {0028-646X},\n\turl = {https://doi.org/10.1111/nph.13655},\n\tdoi = {10.1111/nph.13655},\n\tabstract = {Summary There is compelling evidence from experiments and observations that climate warming prolongs the growing season in arctic regions. Until now, the start, peak, and end of the growing season, which are used to model influences of vegetation on biogeochemical cycles, were commonly quantified using above-ground phenological data. Yet, over 80\\% of the plant biomass in arctic regions can be below ground, and the timing of root growth affects biogeochemical processes by influencing plant water and nutrient uptake, soil carbon input and microbial activity. We measured timing of above- and below-ground production in three plant communities along an arctic elevation gradient over two growing seasons. Below-ground production peaked later in the season and was more temporally uniform than above-ground production. Most importantly, the growing season continued c. 50\\% longer below than above ground. Our results strongly suggest that traditional above-ground estimates of phenology in arctic regions, including remotely sensed information, are not as complete a representation of whole-plant production intensity or duration, as studies that include root phenology. We therefore argue for explicit consideration of root phenology in studies of carbon and nutrient cycling, in terrestrial biosphere models, and scenarios of how arctic ecosystems will respond to climate warming.},\n\tnumber = {3},\n\turldate = {2023-07-21},\n\tjournal = {New Phytologist},\n\tauthor = {Blume-Werry, Gesche and Wilson, Scott D. and Kreyling, Juergen and Milbau, Ann},\n\tmonth = feb,\n\tyear = {2016},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, below ground, below-ground, belowground, fine roots, phenology, root growth, root production, sub-Arctic},\n\tpages = {978--986},\n}\n\n\n\n\n\n Summary There is compelling evidence from experiments and observations that climate warming prolongs the growing season in arctic regions. Until now, the start, peak, and end of the growing season, which are used to model influences of vegetation on biogeochemical cycles, were commonly quantified using above-ground phenological data. Yet, over 80% of the plant biomass in arctic regions can be below ground, and the timing of root growth affects biogeochemical processes by influencing plant water and nutrient uptake, soil carbon input and microbial activity. We measured timing of above- and below-ground production in three plant communities along an arctic elevation gradient over two growing seasons. Below-ground production peaked later in the season and was more temporally uniform than above-ground production. Most importantly, the growing season continued c. 50% longer below than above ground. Our results strongly suggest that traditional above-ground estimates of phenology in arctic regions, including remotely sensed information, are not as complete a representation of whole-plant production intensity or duration, as studies that include root phenology. We therefore argue for explicit consideration of root phenology in studies of carbon and nutrient cycling, in terrestrial biosphere models, and scenarios of how arctic ecosystems will respond to climate warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting Responses of Soil Microbial and Nematode Communities to Warming and Plant Functional Group Removal Across a Post-fire Boreal Forest Successional Gradient.\n \n \n \n \n\n\n \n De Long, J. R.; Dorrepaal, E.; Kardol, P.; Nilsson, M.; Teuber, L. M.; and Wardle, D. A.\n\n\n \n\n\n\n Ecosystems, 19(2): 339–355. March 2016.\n \n\n\n\n
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\n\n\n@article{de_long_contrasting_2016,\n\ttitle = {Contrasting {Responses} of {Soil} {Microbial} and {Nematode} {Communities} to {Warming} and {Plant} {Functional} {Group} {Removal} {Across} a {Post}-fire {Boreal} {Forest} {Successional} {Gradient}},\n\tvolume = {19},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-015-9935-0},\n\tdoi = {10.1007/s10021-015-9935-0},\n\tabstract = {Global warming is causing increases in surface temperatures and has the potential to influence the structure of soil microbial and faunal communities. However, little is known about how warming interacts with other ecosystem drivers, such as plant functional groups or changes associated with succession, to affect the soil community and thereby alter ecosystem functioning. We investigated how experimental warming and the removal of plant functional groups along a post-fire boreal forest successional gradient impacted soil microbial and nematode communities. Our results showed that warming altered soil microbial communities and favored bacterial-based microbial communities, but these effects were mediated by mosses and shrubs, and often varied with successional stage. Meanwhile, the nematode community was generally unaffected by warming and was positively affected by the presence of mosses and shrubs, with these effects mostly independent of successional stage. These results highlight that different groups of soil organisms may respond dissimilarly to interactions between warming and changes to plant functional groups, with likely consequences for ecosystem functioning that may vary with successional stage. Due to the ubiquitous presence of shrubs and mosses in boreal forests, the effects observed in this study are likely to be significant over a large proportion of the terrestrial land surface. Our results demonstrate that it is crucial to consider interactive effects between warming, plant functional groups, and successional stage when predicting soil community responses to global climate change in forested ecosystems.},\n\tnumber = {2},\n\tjournal = {Ecosystems},\n\tauthor = {De Long, Jonathan R. and Dorrepaal, Ellen and Kardol, Paul and Nilsson, Marie-Charlotte and Teuber, Laurenz M. and Wardle, David A.},\n\tmonth = mar,\n\tyear = {2016},\n\tkeywords = {\\#nosource},\n\tpages = {339--355},\n}\n\n\n\n\n\n Global warming is causing increases in surface temperatures and has the potential to influence the structure of soil microbial and faunal communities. However, little is known about how warming interacts with other ecosystem drivers, such as plant functional groups or changes associated with succession, to affect the soil community and thereby alter ecosystem functioning. We investigated how experimental warming and the removal of plant functional groups along a post-fire boreal forest successional gradient impacted soil microbial and nematode communities. Our results showed that warming altered soil microbial communities and favored bacterial-based microbial communities, but these effects were mediated by mosses and shrubs, and often varied with successional stage. Meanwhile, the nematode community was generally unaffected by warming and was positively affected by the presence of mosses and shrubs, with these effects mostly independent of successional stage. These results highlight that different groups of soil organisms may respond dissimilarly to interactions between warming and changes to plant functional groups, with likely consequences for ecosystem functioning that may vary with successional stage. Due to the ubiquitous presence of shrubs and mosses in boreal forests, the effects observed in this study are likely to be significant over a large proportion of the terrestrial land surface. Our results demonstrate that it is crucial to consider interactive effects between warming, plant functional groups, and successional stage when predicting soil community responses to global climate change in forested ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Cryogenic soil processes in a changing climate.\n \n \n \n \n\n\n \n Becher, M.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2016.\n Publisher: Umeå universitet\n\n\n\n
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\n\n\n@phdthesis{becher_cryogenic_2016,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Cryogenic soil processes in a changing climate},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-112509},\n\tabstract = {A considerable part of the global pool of terrestrial carbon is stored in high latitude soils. In these soils, repeated cycles of freezing and thawing creates soil motion (cryoturbation) that in co ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Becher, Marina},\n\tcollaborator = {Klaminder, Jonatan and Olofsson, Johan and Karlsson, Jan and Börlin, Niclas},\n\tyear = {2016},\n\tnote = {Publisher: Umeå universitet},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n A considerable part of the global pool of terrestrial carbon is stored in high latitude soils. In these soils, repeated cycles of freezing and thawing creates soil motion (cryoturbation) that in co ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Oxygen transport in periodically ventilated polychaete burrows.\n \n \n \n \n\n\n \n Murphy, E. A. K.; and Reidenbach, M. A.\n\n\n \n\n\n\n Marine Biology, 163(10): 208. September 2016.\n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{murphy_oxygen_2016,\n\ttitle = {Oxygen transport in periodically ventilated polychaete burrows},\n\tvolume = {163},\n\tissn = {1432-1793},\n\turl = {https://doi.org/10.1007/s00227-016-2983-y},\n\tdoi = {10.1007/s00227-016-2983-y},\n\tabstract = {Burrowing organisms play a critical role for the functioning of coastal marine sediments, in part due to their pumping of oxygenated water through the burrow. In cohesive sediments, oxygenated burrow water allows for the diffusive flux of oxygen across the burrow wall and into the sediment, where it is consumed. In this study, we quantified the burrow excurrent velocities, volume of water ventilated and oxygenation patterns within the burrow of the polychaete Alitta succinea. We determined that periodic ventilation of the burrow results in oscillations of the flux of oxygen across the burrow wall and oxygen concentration within the sediment near the burrow wall. Additionally, we investigated the effects of temperature changes on oxygen dynamics in the burrow. The volumetric flow rate and frequency of burrow ventilation increased with temperature. Correspondingly, the frequency of the oscillations in oxygen flux across the burrow walls also increased with temperature. However, the time-averaged flux of oxygen across the burrow wall did not change with temperature (1.5 ± 0.3ol m−2 d−1), and the distance of oxygen penetration into the burrow wall decreased with temperature (from 3.4 ± 0.5 at 6 °C to 1.6 ± 0.1 at 33 °C). Thus, seasonal changes in the volume of oxygenated sediment, as well as the pattern of oxygenation that sediment experiences, are expected to be significant while the total oxygen flux is expected to remain relatively uniform. We show that burrower ventilation behavior mediates the effects of temperature on sediment oxygen uptake.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2019-07-16},\n\tjournal = {Marine Biology},\n\tauthor = {Murphy, Elizabeth A. K. and Reidenbach, Matthew A.},\n\tmonth = sep,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Intertidal Mudflat, Oxygen Flux, Particle Image Velocimetry, Polychaete, Volumetric Flow Rate},\n\tpages = {208},\n}\n\n\n\n\n\n Burrowing organisms play a critical role for the functioning of coastal marine sediments, in part due to their pumping of oxygenated water through the burrow. In cohesive sediments, oxygenated burrow water allows for the diffusive flux of oxygen across the burrow wall and into the sediment, where it is consumed. In this study, we quantified the burrow excurrent velocities, volume of water ventilated and oxygenation patterns within the burrow of the polychaete Alitta succinea. We determined that periodic ventilation of the burrow results in oscillations of the flux of oxygen across the burrow wall and oxygen concentration within the sediment near the burrow wall. Additionally, we investigated the effects of temperature changes on oxygen dynamics in the burrow. The volumetric flow rate and frequency of burrow ventilation increased with temperature. Correspondingly, the frequency of the oscillations in oxygen flux across the burrow walls also increased with temperature. However, the time-averaged flux of oxygen across the burrow wall did not change with temperature (1.5 ± 0.3ol m−2 d−1), and the distance of oxygen penetration into the burrow wall decreased with temperature (from 3.4 ± 0.5 at 6 °C to 1.6 ± 0.1 at 33 °C). Thus, seasonal changes in the volume of oxygenated sediment, as well as the pattern of oxygenation that sediment experiences, are expected to be significant while the total oxygen flux is expected to remain relatively uniform. We show that burrower ventilation behavior mediates the effects of temperature on sediment oxygen uptake.\n
\n\n\n\n \n\n \n \n \n \n \n \n Geothermal ecosystems as natural climate change experiments: The ForHot research site in Iceland as a case study.\n \n \n \n \n\n\n \n Sigurdsson, B. D; Leblans, N. I W; Dauwe, S.; Guðmundsdóttir, E.; Gundersen, P.; Gunnarsdóttir, G. E; Holmstrup, M.; Ilieva-Makulec, K.; Kätterer, T.; Marteinsdóttir, B.; Maljanen, M.; Oddsdóttir, E. S; Ostonen, I.; Peñuelas, J.; Poeplau, C.; Richter, A.; Sigurðsson, P.; van Bodegom, P.; Wallander, H.; Weedon, J.; and Janssens, I.\n\n\n \n\n\n\n Icelandic Agricultural Sciences, 29: 53–71. 2016.\n \n\n\n\n
\n\n\n\n \n \n![\"Geothermal](\"//bibbase.org/img/filetypes/pdf.svg\"\n\t "\\"Paper\\"\n\t")
Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{sigurdsson_geothermal_2016,\n\ttitle = {Geothermal ecosystems as natural climate change experiments: {The} {ForHot} research site in {Iceland} as a case study},\n\tvolume = {29},\n\tissn = {2298786X},\n\tshorttitle = {Geothermal ecosystems as natural climate change experiments},\n\turl = {http://ias.is/wp-content/uploads/Icelandic_Agricultural_Sciences_29_2016/Geothermal-ecosystems-as-natural-climate-change-experiments.pdf},\n\tdoi = {10.16886/IAS.2016.05},\n\tabstract = {This article describes how natural geothermal soil temperature gradients in Iceland have been used to study terrestrial ecosystem responses to soil warming. The experimental approach was evaluated at three study sites in southern Iceland; one grassland site that has been warm for at least 50 years (GO), and another comparable grassland site (GN) and a Sitka spruce plantation (FN) site that have both been warmed since an earthquake took place in 2008. Within each site type, five ca. 50 m long transects, with six permanent study plots each, were established across the soil warming gradients, spanning from unwarmed control conditions to gradually warmer soils. It was attempted to select the plots so the annual warming levels would be ca. +1, +3, +5, +10 and +20 °C within each transect. Results of continuous measurements of soil temperature (Ts) from 2013-2015 revealed that the soil warming was relatively constant and followed the seasonal Ts cycle of the unwarmed control plots. Volumetric water content in the top 5 cm of soil was repeatedly surveyed during 2013-2016. The grassland soils were wetter than the FN soils, but they had sometimes some significant warming-induced drying in the surface layer of the warmest plots, in contrast to FN. Soil chemistry did not show any indications that geothermal water had reached the root zone, but soil pH did increase somewhat with warming, which was probably linked to vegetation changes. As expected, the potential decomposition rate of organic matter increased significantly with warming. It was concluded that the natural geothermal gradients at the ForHot sites in Iceland offered realistic conditions for studying terrestrial ecosystem responses to warming with minimal artefacts.},\n\tlanguage = {en},\n\turldate = {2019-05-20},\n\tjournal = {Icelandic Agricultural Sciences},\n\tauthor = {Sigurdsson, Bjarni D and Leblans, Niki I W and Dauwe, Steven and Guðmundsdóttir, Elín and Gundersen, Per and Gunnarsdóttir, Gunnhildur E and Holmstrup, Martin and Ilieva-Makulec, Krassimira and Kätterer, Thomas and Marteinsdóttir, Bryndís and Maljanen, Marja and Oddsdóttir, Edda S and Ostonen, Ivika and Peñuelas, Josep and Poeplau, Christopher and Richter, Andreas and Sigurðsson, Páll and van Bodegom, Peter and Wallander, Håkan and Weedon, James and Janssens, Ivan},\n\tyear = {2016},\n\tkeywords = {\\#nosource},\n\tpages = {53--71},\n}\n\n\n\n\n\n This article describes how natural geothermal soil temperature gradients in Iceland have been used to study terrestrial ecosystem responses to soil warming. The experimental approach was evaluated at three study sites in southern Iceland; one grassland site that has been warm for at least 50 years (GO), and another comparable grassland site (GN) and a Sitka spruce plantation (FN) site that have both been warmed since an earthquake took place in 2008. Within each site type, five ca. 50 m long transects, with six permanent study plots each, were established across the soil warming gradients, spanning from unwarmed control conditions to gradually warmer soils. It was attempted to select the plots so the annual warming levels would be ca. +1, +3, +5, +10 and +20 °C within each transect. Results of continuous measurements of soil temperature (Ts) from 2013-2015 revealed that the soil warming was relatively constant and followed the seasonal Ts cycle of the unwarmed control plots. Volumetric water content in the top 5 cm of soil was repeatedly surveyed during 2013-2016. The grassland soils were wetter than the FN soils, but they had sometimes some significant warming-induced drying in the surface layer of the warmest plots, in contrast to FN. Soil chemistry did not show any indications that geothermal water had reached the root zone, but soil pH did increase somewhat with warming, which was probably linked to vegetation changes. As expected, the potential decomposition rate of organic matter increased significantly with warming. It was concluded that the natural geothermal gradients at the ForHot sites in Iceland offered realistic conditions for studying terrestrial ecosystem responses to warming with minimal artefacts.\n
\n\n\n\n \n\n \n \n \n \n \n \n Passing the point of no return.\n \n \n \n \n\n\n \n Seekell, D. A.\n\n\n \n\n\n\n Science, 354(6316): 1109–1109. December 2016.\n 00000 \n\n\n\n
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\n\n\n@article{seekell_passing_2016,\n\ttitle = {Passing the point of no return},\n\tvolume = {354},\n\tcopyright = {Copyright © 2016, American Association for the Advancement of Science},\n\tissn = {0036-8075, 1095-9203},\n\turl = {http://science.sciencemag.org/content/354/6316/1109.3},\n\tdoi = {10.1126/science.aal2188},\n\tabstract = {Early warning signals indicate impending ecosystem regime changes\nEarly warning signals indicate impending ecosystem regime changes},\n\tlanguage = {en},\n\tnumber = {6316},\n\turldate = {2016-12-11},\n\tjournal = {Science},\n\tauthor = {Seekell, David A.},\n\tmonth = dec,\n\tyear = {2016},\n\tpmid = {27934729},\n\tnote = {00000 },\n\tkeywords = {\\#nosource},\n\tpages = {1109--1109},\n}\n\n\n\n\n\n Early warning signals indicate impending ecosystem regime changes Early warning signals indicate impending ecosystem regime changes\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of experimental snowmelt and rain on dispersal of six plant species.\n \n \n \n \n\n\n \n Sarneel, J. M.\n\n\n \n\n\n\n Ecohydrology, 9(8): 1464–1470. 2016.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{sarneel_effects_2016,\n\ttitle = {Effects of experimental snowmelt and rain on dispersal of six plant species},\n\tvolume = {9},\n\tcopyright = {© 2016 The Authors. Ecohydrology published by John Wiley \\& Sons Ltd.},\n\tissn = {1936-0592},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1002/eco.1739},\n\tdoi = {10.1002/eco.1739},\n\tabstract = {Water flows affect dispersal of propagules of many plant species, and rivers and streams are therefore very important dispersal vectors. However, small water flows such as trough rain and snowmelt are much more common, but their effects on dispersal are barely studied. The importance of this form of dispersal deserves attention, especially when considering that climate change is predicted to change the amounts of rain and snow worldwide. Dispersal through melting snow and rain was addressed experimentally, using artificial soils mounted on slopes with different angles and subjected to a melting snow pack or an equivalent amount of dripping water. Seeds on the soil moved on average 3·02 cm (±1·81 SE) in rain treatments and 0·23 cm (±0·3 SE) in snowmelt treatments. Tracking plastic granules in field conditions further showed that snowmelt exhibited minimal dispersal capacity. Dispersal distances by rain were enhanced by increasing slope angles and with decreasing seed volume. Given that many species in cold environments have small seeds, dispersal by rain could provide an important (secondary) dispersal mechanism in these habitats. © 2016 The Authors. Ecohydrology published by John Wiley \\& Sons Ltd.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2019-04-05},\n\tjournal = {Ecohydrology},\n\tauthor = {Sarneel, J. M.},\n\tyear = {2016},\n\tkeywords = {\\#nosource, boreal ecosystems, bythisochory, climate change, dispersal vector, erosion, hydrochory, rain, snow},\n\tpages = {1464--1470},\n}\n\n\n\n\n\n Water flows affect dispersal of propagules of many plant species, and rivers and streams are therefore very important dispersal vectors. However, small water flows such as trough rain and snowmelt are much more common, but their effects on dispersal are barely studied. The importance of this form of dispersal deserves attention, especially when considering that climate change is predicted to change the amounts of rain and snow worldwide. Dispersal through melting snow and rain was addressed experimentally, using artificial soils mounted on slopes with different angles and subjected to a melting snow pack or an equivalent amount of dripping water. Seeds on the soil moved on average 3·02 cm (±1·81 SE) in rain treatments and 0·23 cm (±0·3 SE) in snowmelt treatments. Tracking plastic granules in field conditions further showed that snowmelt exhibited minimal dispersal capacity. Dispersal distances by rain were enhanced by increasing slope angles and with decreasing seed volume. Given that many species in cold environments have small seeds, dispersal by rain could provide an important (secondary) dispersal mechanism in these habitats. © 2016 The Authors. Ecohydrology published by John Wiley & Sons Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n Root production in contrasting ecosystems: the impact of rhizotron sampling frequency.\n \n \n \n \n\n\n \n Balogianni, V. G.; Blume-Werry, G.; and Wilson, S. D.\n\n\n \n\n\n\n Plant Ecology, 217(11): 1359–1367. November 2016.\n 00002\n\n\n\n
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\n\n\n@article{balogianni_root_2016,\n\ttitle = {Root production in contrasting ecosystems: the impact of rhizotron sampling frequency},\n\tvolume = {217},\n\tissn = {1385-0237, 1573-5052},\n\tshorttitle = {Root production in contrasting ecosystems},\n\turl = {http://link.springer.com/article/10.1007/s11258-016-0588-7},\n\tdoi = {10.1007/s11258-016-0588-7},\n\tabstract = {Despite their critical role in every terrestrial ecosystem, fine root production and mortality have not been widely compared among systems due to the practical difficulties of belowground research. We examined fine root production and mortality among five contrasting sites: native and invaded grassland in eastern Montana, USA, aspen forest in southern Saskatchewan, Canada, and birch forest and tundra in northern Sweden. Additionally, we investigated the importance of minirhizotron sampling interval on measures of root production and mortality by comparing measures produced from 1-, 7-, 14-, and 21-day sample intervals. Root length and mortality varied significantly among sites, with invaded grassland having the greatest root length ({\\textgreater}2 × than any other site) and significantly greater root mortality than native grassland (54 \\%). In contrast, there were no significant differences in root production among the sites. Sample interval had no significant influence on root production or mortality. Minirhizotron sampling intervals up to 3 weeks did not underestimate the measures of root production and mortality in comparison to measures derived from shorter sampling intervals, regardless of the site studied. The results suggest that 3 weeks can be an accurate and efficient sample interval when studying root production and mortality with minirhizotrons.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2017-02-07},\n\tjournal = {Plant Ecology},\n\tauthor = {Balogianni, Vasiliki G. and Blume-Werry, Gesche and Wilson, Scott D.},\n\tmonth = nov,\n\tyear = {2016},\n\tnote = {00002},\n\tkeywords = {\\#nosource, Arctic, Minirhizotrons, Plant Sciences, Prairie, Sample interval, mortality, tundra},\n\tpages = {1359--1367},\n}\n\n\n\n\n\n Despite their critical role in every terrestrial ecosystem, fine root production and mortality have not been widely compared among systems due to the practical difficulties of belowground research. We examined fine root production and mortality among five contrasting sites: native and invaded grassland in eastern Montana, USA, aspen forest in southern Saskatchewan, Canada, and birch forest and tundra in northern Sweden. Additionally, we investigated the importance of minirhizotron sampling interval on measures of root production and mortality by comparing measures produced from 1-, 7-, 14-, and 21-day sample intervals. Root length and mortality varied significantly among sites, with invaded grassland having the greatest root length (\\textgreater2 × than any other site) and significantly greater root mortality than native grassland (54 %). In contrast, there were no significant differences in root production among the sites. Sample interval had no significant influence on root production or mortality. Minirhizotron sampling intervals up to 3 weeks did not underestimate the measures of root production and mortality in comparison to measures derived from shorter sampling intervals, regardless of the site studied. The results suggest that 3 weeks can be an accurate and efficient sample interval when studying root production and mortality with minirhizotrons.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of elevation and nitrogen and phosphorus fertilization on plant defence compounds in subarctic tundra heath vegetation.\n \n \n \n \n\n\n \n De Long, J. R.; Sundqvist, M. K.; Gundale, M. J.; Giesler, R.; and Wardle, D. A.\n\n\n \n\n\n\n Functional Ecology, 30(2): 314–325. February 2016.\n 00006\n\n\n\n
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\n\n\n@article{de_long_effects_2016,\n\ttitle = {Effects of elevation and nitrogen and phosphorus fertilization on plant defence compounds in subarctic tundra heath vegetation},\n\tvolume = {30},\n\tissn = {1365-2435},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12493/abstract},\n\tdoi = {10.1111/1365-2435.12493},\n\tabstract = {* Plant chemical and structural defence compounds are well known to impact upon herbivory of fresh leaves and influence decomposition rates after leaf senescence. A number of theories predict that alleviating nutrient limitation and reducing other environmental stressors will result in decreased production of plant chemical defences.\n\n\n* In this study, we measured plant defence properties [total polyphenols (TP), condensed tannins (CT) and lignin concentrations, and protein complexation capacity (PCC)] in both fresh and senesced plant leaves in a fully factorial N and P fertilization experiment set-up at each of three elevations along an elevational gradient in Swedish subarctic tundra heath vegetation. Further, we performed a decomposition of variance analysis on community-weighted averages (CWAs) of plant defence properties to determine the relative contributions of interspecific and intraspecific variation to the total variation observed in response to elevation and nutrient addition.\n\n\n* We hypothesized that N fertilization would reduce plant defence properties and that this reduction would be greater at higher elevations, while the effects of P fertilization would have no effect at any elevation.\n\n\n* At the community level, N addition reduced CT and PCC in both fresh and senesced leaves and TP in senesced leaves, while P addition had few effects, broadly in line with our hypothesis. The effects of N addition frequently varied with elevation, but in contrast to our hypothesis, the said effects were strongest at the lowest elevations. The effects of N addition and the interactive effect of N with elevation were primarily driven by intraspecific, rather than interspecific, variation.\n\n\n* Our findings suggest that as temperatures warm and N availability increases due to global climate change, secondary metabolites in subarctic heath vegetation will decline particularly within species. Our results highlight the need to consider the effects of both nutrient availability and temperature, and their interaction, in driving subarctic plant defence.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-07},\n\tjournal = {Functional Ecology},\n\tauthor = {De Long, Jonathan R. and Sundqvist, Maja K. and Gundale, Michael J. and Giesler, Reiner and Wardle, David A.},\n\tmonth = feb,\n\tyear = {2016},\n\tnote = {00006},\n\tkeywords = {\\#nosource, Decomposition, Global climate change, condensed tannins, litter feedback, nutrient addition, plant defence theory, protein complexation capacity, subarctic tundra},\n\tpages = {314--325},\n}\n\n\n\n\n\n * Plant chemical and structural defence compounds are well known to impact upon herbivory of fresh leaves and influence decomposition rates after leaf senescence. A number of theories predict that alleviating nutrient limitation and reducing other environmental stressors will result in decreased production of plant chemical defences. * In this study, we measured plant defence properties [total polyphenols (TP), condensed tannins (CT) and lignin concentrations, and protein complexation capacity (PCC)] in both fresh and senesced plant leaves in a fully factorial N and P fertilization experiment set-up at each of three elevations along an elevational gradient in Swedish subarctic tundra heath vegetation. Further, we performed a decomposition of variance analysis on community-weighted averages (CWAs) of plant defence properties to determine the relative contributions of interspecific and intraspecific variation to the total variation observed in response to elevation and nutrient addition. * We hypothesized that N fertilization would reduce plant defence properties and that this reduction would be greater at higher elevations, while the effects of P fertilization would have no effect at any elevation. * At the community level, N addition reduced CT and PCC in both fresh and senesced leaves and TP in senesced leaves, while P addition had few effects, broadly in line with our hypothesis. The effects of N addition frequently varied with elevation, but in contrast to our hypothesis, the said effects were strongest at the lowest elevations. The effects of N addition and the interactive effect of N with elevation were primarily driven by intraspecific, rather than interspecific, variation. * Our findings suggest that as temperatures warm and N availability increases due to global climate change, secondary metabolites in subarctic heath vegetation will decline particularly within species. Our results highlight the need to consider the effects of both nutrient availability and temperature, and their interaction, in driving subarctic plant defence.\n
\n\n\n\n \n\n \n \n \n \n \n \n The effects of temperature and resource availability on denitrification and relative N2O production in boreal lake sediments.\n \n \n \n \n\n\n \n Myrstener, M.; Jonsson, A.; and Bergström, A.\n\n\n \n\n\n\n Journal of Environmental Sciences, 47: 82–90. September 2016.\n 00000\n\n\n\n
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\n\n\n@article{myrstener_effects_2016,\n\ttitle = {The effects of temperature and resource availability on denitrification and relative {N2O} production in boreal lake sediments},\n\tvolume = {47},\n\tissn = {1001-0742},\n\turl = {https://www.sciencedirect.com/science/article/pii/S1001074216300328},\n\tdoi = {10.1016/j.jes.2016.03.003},\n\tabstract = {Anthropogenic environmental stressors (like atmospheric deposition, land use change, and climate warming) are predicted to increase inorganic nitrogen and organic carbon loading to northern boreal lakes, with potential consequences for denitrification in lakes. However, our ability to predict effects of these changes is currently limited as northern boreal lakes have been largely neglected in denitrification studies. The aim of this study was therefore to assess how maximum potential denitrification and N2O production rates, and the relationship between the two (relative N2O production), is controlled by availability of nitrate (NO3−), carbon (C), phosphorus (P), and temperature. Experiments were performed using the acetylene inhibition technique on sediments from a small, nutrient poor boreal lake in northern Sweden in 2014. Maximum potential denitrification and N2O production rates at 4°C were reached already at NO3− additions of 106–120 μg NO3−–N/L, and remained unchanged with higher NO3 amendments. Higher incubation temperatures increased maximum potential denitrification and N2O production rates, and Q10 was somewhat higher for N2O production (1.77) than for denitrification (1.69). The relative N2O production ranged between 13\\% and 64\\%, and was not related to NO3− concentration, but the ratio increased when incubations were amended with C and P (from a median of 16\\% to 27\\%). Combined, our results suggests that unproductive northern boreal lakes currently have low potential for denitrification but are susceptible to small changes in NO3 loading especially if these are accompanied by enhanced C and P availability, likely promoting higher N2O production relative to N2.},\n\turldate = {2017-02-08},\n\tjournal = {Journal of Environmental Sciences},\n\tauthor = {Myrstener, Maria and Jonsson, Anders and Bergström, Ann-Kristin},\n\tmonth = sep,\n\tyear = {2016},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Acetylene, DOC, NO3, Nitrous oxide ratio, Sediment, carbon},\n\tpages = {82--90},\n}\n\n\n\n\n\n Anthropogenic environmental stressors (like atmospheric deposition, land use change, and climate warming) are predicted to increase inorganic nitrogen and organic carbon loading to northern boreal lakes, with potential consequences for denitrification in lakes. However, our ability to predict effects of these changes is currently limited as northern boreal lakes have been largely neglected in denitrification studies. The aim of this study was therefore to assess how maximum potential denitrification and N2O production rates, and the relationship between the two (relative N2O production), is controlled by availability of nitrate (NO3−), carbon (C), phosphorus (P), and temperature. Experiments were performed using the acetylene inhibition technique on sediments from a small, nutrient poor boreal lake in northern Sweden in 2014. Maximum potential denitrification and N2O production rates at 4°C were reached already at NO3− additions of 106–120 μg NO3−–N/L, and remained unchanged with higher NO3 amendments. Higher incubation temperatures increased maximum potential denitrification and N2O production rates, and Q10 was somewhat higher for N2O production (1.77) than for denitrification (1.69). The relative N2O production ranged between 13% and 64%, and was not related to NO3− concentration, but the ratio increased when incubations were amended with C and P (from a median of 16% to 27%). Combined, our results suggests that unproductive northern boreal lakes currently have low potential for denitrification but are susceptible to small changes in NO3 loading especially if these are accompanied by enhanced C and P availability, likely promoting higher N2O production relative to N2.\n
\n\n\n\n \n\n \n \n \n \n \n \n Herbivores influence nutrient cycling and plant nutrient uptake : insights from tundra ecosystems.\n \n \n \n \n\n\n \n Barthelemy, H.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2016.\n ISBN: 978-91-7601-456-1 (print)\n\n\n\n
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\n\n\n@phdthesis{barthelemy_herbivores_2016,\n\taddress = {Umeå, Sweden},\n\ttitle = {Herbivores influence nutrient cycling and plant nutrient uptake : insights from tundra ecosystems},\n\tshorttitle = {Herbivores influence nutrient cycling and plant nutrient uptake},\n\turl = {http://www.diva-portal.org/smash/record.jsf?pid=diva2:927068},\n\tabstract = {Reindeer appear to have strong positive effects on plant productivity and nutrient cycling in strongly nutrient-limited ecosystems. While the direct effects of grazing on vegetation composition hav ...},\n\tlanguage = {eng},\n\turldate = {2017-02-08},\n\tschool = {Umeå University},\n\tauthor = {Barthelemy, Hélène},\n\tyear = {2016},\n\tnote = {ISBN: 978-91-7601-456-1 (print)},\n\tkeywords = {\\#nosource, 15N stable isotopes, Reindeer grazing, arctic, crobial communities, dung and urine, large herbivore, nutrient cycling, plant nutrient uptake, plant, plant ecology, soil interactions, soil nutrient availability, ⛔ No DOI found},\n}\n\n\n\n\n\n Reindeer appear to have strong positive effects on plant productivity and nutrient cycling in strongly nutrient-limited ecosystems. While the direct effects of grazing on vegetation composition hav ...\n
\n\n\n\n \n\n \n \n \n \n \n \n The hidden life of plants : fine root dynamics in northern ecosystems.\n \n \n \n \n\n\n \n Blume-Werry, G.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2016.\n ISBN: 978-91-7601-533-9 (print)\n\n\n\n
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\n\n\n@phdthesis{blume-werry_hidden_2016,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {The hidden life of plants : fine root dynamics in northern ecosystems},\n\tshorttitle = {The hidden life of plants},\n\turl = {http://umu.diva-portal.org/smash/record.jsf?pid=diva2:954761},\n\tabstract = {Fine roots constitute a large part of the primary production in northern (arctic and boreal) ecosystems, and are key players in ecosystem fluxes of water, nutrients and carbon. Data on root dynamic ...},\n\tlanguage = {eng},\n\turldate = {2017-02-07},\n\tschool = {Umeå University},\n\tauthor = {Blume-Werry, Gesche},\n\tcollaborator = {Jansson, Roland and Milbau, Ann and Wilson, Scott D.},\n\tyear = {2016},\n\tnote = {ISBN: 978-91-7601-533-9 (print)},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Fine roots constitute a large part of the primary production in northern (arctic and boreal) ecosystems, and are key players in ecosystem fluxes of water, nutrients and carbon. Data on root dynamic ...\n
\n\n\n\n \n\n \n \n \n \n \n \n What commodities and countries impact inequality in the global food system?.\n \n \n \n \n\n\n \n Carr, J. A.; D’Odorico, P.; Suweis, S.; and Seekell, D. A.\n\n\n \n\n\n\n Environmental Research Letters, 11(9): 095013. 2016.\n 00000\n\n\n\n
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\n\n\n@article{carr_what_2016,\n\ttitle = {What commodities and countries impact inequality in the global food system?},\n\tvolume = {11},\n\tissn = {1748-9326},\n\turl = {http://stacks.iop.org/1748-9326/11/i=9/a=095013},\n\tdoi = {10.1088/1748-9326/11/9/095013},\n\tabstract = {The global distribution of food production is unequal relative to the distribution of human populations. International trade can increase or decrease inequality in food availability, but little is known about how specific countries and commodities contribute to this redistribution. We present a method based on the Gini coefficient for evaluating the contributions of country and commodity specific trade to inequality in the global food system. We applied the method to global food production and trade data for the years 1986–2011 to identify the specific countries and commodities that contribute to increasing and decreasing inequality in global food availability relative to food production. Overall, international trade reduced inequality in food availability by 25\\%–33\\% relative to the distribution of food production, depending on the year. Across all years, about 58\\% of the total trade links acted to reduce inequality with ∼4\\% of the links providing 95\\% of the reduction in inequality. Exports from United States of America, Malaysia, Argentina, and Canada are particularly important in decreasing inequality. Specific commodities that reduce inequality when traded include cereals and vegetables. Some trade connections contribute to increasing inequality, but this effect is mostly concentrated within a small number of commodities including fruits, stimulants, and nuts. In terms of specific countries, exports from Slovenia, Oman, Singapore, and Germany act to increase overall inequality. Collectively, our analysis and results represent an opportunity for building an enhanced understanding of global-scale patterns in food availability.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2016-10-03},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Carr, Joel A. and D’Odorico, Paolo and Suweis, Samir and Seekell, David A.},\n\tyear = {2016},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {095013},\n}\n\n\n\n\n\n The global distribution of food production is unequal relative to the distribution of human populations. International trade can increase or decrease inequality in food availability, but little is known about how specific countries and commodities contribute to this redistribution. We present a method based on the Gini coefficient for evaluating the contributions of country and commodity specific trade to inequality in the global food system. We applied the method to global food production and trade data for the years 1986–2011 to identify the specific countries and commodities that contribute to increasing and decreasing inequality in global food availability relative to food production. Overall, international trade reduced inequality in food availability by 25%–33% relative to the distribution of food production, depending on the year. Across all years, about 58% of the total trade links acted to reduce inequality with ∼4% of the links providing 95% of the reduction in inequality. Exports from United States of America, Malaysia, Argentina, and Canada are particularly important in decreasing inequality. Specific commodities that reduce inequality when traded include cereals and vegetables. Some trade connections contribute to increasing inequality, but this effect is mostly concentrated within a small number of commodities including fruits, stimulants, and nuts. In terms of specific countries, exports from Slovenia, Oman, Singapore, and Germany act to increase overall inequality. Collectively, our analysis and results represent an opportunity for building an enhanced understanding of global-scale patterns in food availability.\n
\n\n\n\n \n\n \n \n \n \n \n \n Reserves and trade jointly determine exposure to food supply shocks.\n \n \n \n \n\n\n \n Marchand, P.; Carr, J. A.; Dell’Angelo, J.; Fader, M.; Gephart, J. A.; Matti Kummu; Magliocca, N. R.; Porkka, M.; Puma, M. J.; Ratajczak, Z.; Rulli, M. C.; Seekell, D. A.; Suweis, S.; Tavoni, A.; and D’Odorico, P.\n\n\n \n\n\n\n Environmental Research Letters, 11(9): 095009. 2016.\n 00005\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{marchand_reserves_2016,\n\ttitle = {Reserves and trade jointly determine exposure to food supply shocks},\n\tvolume = {11},\n\tissn = {1748-9326},\n\turl = {http://stacks.iop.org/1748-9326/11/i=9/a=095009},\n\tdoi = {10.1088/1748-9326/11/9/095009},\n\tabstract = {While a growing proportion of global food consumption is obtained through international trade, there is an ongoing debate on whether this increased reliance on trade benefits or hinders food security, and specifically, the ability of global food systems to absorb shocks due to local or regional losses of production. This paper introduces a model that simulates the short-term response to a food supply shock originating in a single country, which is partly absorbed through decreases in domestic reserves and consumption, and partly transmitted through the adjustment of trade flows. By applying the model to publicly-available data for the cereals commodity group over a 17 year period, we find that differential outcomes of supply shocks simulated through this time period are driven not only by the intensification of trade, but as importantly by changes in the distribution of reserves. Our analysis also identifies countries where trade dependency may accentuate the risk of food shortages from foreign production shocks; such risk could be reduced by increasing domestic reserves or importing food from a diversity of suppliers that possess their own reserves. This simulation-based model provides a framework to study the short-term, nonlinear and out-of-equilibrium response of trade networks to supply shocks, and could be applied to specific scenarios of environmental or economic perturbations.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2016-09-26},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Marchand, Philippe and Carr, Joel A. and Dell’Angelo, Jampel and Fader, Marianela and Gephart, Jessica A. and {Matti Kummu} and Magliocca, Nicholas R. and Porkka, Miina and Puma, Michael J. and Ratajczak, Zak and Rulli, Maria Cristina and Seekell, David A. and Suweis, Samir and Tavoni, Alessandro and D’Odorico, Paolo},\n\tyear = {2016},\n\tnote = {00005},\n\tkeywords = {\\#nosource},\n\tpages = {095009},\n}\n\n\n\n\n\n While a growing proportion of global food consumption is obtained through international trade, there is an ongoing debate on whether this increased reliance on trade benefits or hinders food security, and specifically, the ability of global food systems to absorb shocks due to local or regional losses of production. This paper introduces a model that simulates the short-term response to a food supply shock originating in a single country, which is partly absorbed through decreases in domestic reserves and consumption, and partly transmitted through the adjustment of trade flows. By applying the model to publicly-available data for the cereals commodity group over a 17 year period, we find that differential outcomes of supply shocks simulated through this time period are driven not only by the intensification of trade, but as importantly by changes in the distribution of reserves. Our analysis also identifies countries where trade dependency may accentuate the risk of food shortages from foreign production shocks; such risk could be reduced by increasing domestic reserves or importing food from a diversity of suppliers that possess their own reserves. This simulation-based model provides a framework to study the short-term, nonlinear and out-of-equilibrium response of trade networks to supply shocks, and could be applied to specific scenarios of environmental or economic perturbations.\n
\n\n\n\n \n\n \n \n \n \n \n \n Climate change will alter amphibian-mediated nutrient pathways: evidence from Rana temporaria tadpoles in experimental ponds.\n \n \n \n \n\n\n \n Norlin, L.; Byström, P.; Karlsson, J.; Johansson, M.; and Liess, A.\n\n\n \n\n\n\n Freshwater Biology, 61(4): 472–485. April 2016.\n \n\n\n\n
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\n\n\n@article{norlin_climate_2016,\n\ttitle = {Climate change will alter amphibian-mediated nutrient pathways: evidence from {Rana} temporaria tadpoles in experimental ponds},\n\tvolume = {61},\n\tissn = {1365-2427},\n\tshorttitle = {Climate change will alter amphibian-mediated nutrient pathways},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/fwb.12720/abstract},\n\tdoi = {10.1111/fwb.12720},\n\tabstract = {* With global warming, mean temperatures and brownification of many waterbodies are predicted to increase. This may have unknown consequences on aquatic consumer life histories and nutrient content, consumer-mediated nutrient recycling, and nutrient transport between water and land.\n\n\n* Using a large-scale experimental pond facility, we altered temperature (ambient/+4 °C) and brownification (clear/humic) in a 2 × 2 factorial design (n = 16 pond sections) to test two aspects of climate change on Rana temporaria tadpole life-history traits and on tadpole-mediated nutrient pathways. On day 16 after hatching, we examined tadpole-mediated nutrient recycling by measuring tadpole nutrient excretion and egestion rates and tadpole body nutrient content. We estimated tadpole growth and development rates from hatching to emergence and measured emergent frog body size and body nutrient content.\n\n\n* Brownification increased total pond water nutrient availability and total pond water nitrogen (N) : phosphorous (P) ratios. Warming positively affected tadpole growth and development rates, whereas browning increased tadpole growth rate only under ambient temperatures. Emergent frog body P content decreased with warming, but only in the clear treatments. But despite these variations in body nutrient content, body stoichiometry remained within a relatively narrow stoichiometric range for both emergent frogs (P content: 1.4–1.8\\%, N content: 11.4–11.8\\% and carbon [C] content: 46.9–51.3\\%) and tadpoles (P content: 1.1–1.2\\%, N content: 10.1–11.7\\% and C content: 48.0–50.5\\%). Warming increased tadpole body P content and browning had a positive effect on tadpole body N content and tadpole N excretion rates, probably mediated by the increased pond water total N availability.\n\n\n* We conclude that warming and brownification will interact in changing aquatic consumer growth and body nutrient stoichiometry. In addition, warming has the potential to affect emergent frog body nutrient content and may thus affect nutrient transport from water to land. Last, by increasing pond water N availability, brownification appears to intensify consumer P limitation and thus amplify consumer-meditated N recycling.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-06},\n\tjournal = {Freshwater Biology},\n\tauthor = {Norlin, Linnea and Byström, Pär and Karlsson, Jan and Johansson, Martin and Liess, Antonia},\n\tmonth = apr,\n\tyear = {2016},\n\tkeywords = {\\#nosource, aquatic subsidies, ecological stoichiometry, homeostasis, nutrient release, terrestrial subsidies},\n\tpages = {472--485},\n}\n\n\n\n\n\n * With global warming, mean temperatures and brownification of many waterbodies are predicted to increase. This may have unknown consequences on aquatic consumer life histories and nutrient content, consumer-mediated nutrient recycling, and nutrient transport between water and land. * Using a large-scale experimental pond facility, we altered temperature (ambient/+4 °C) and brownification (clear/humic) in a 2 × 2 factorial design (n = 16 pond sections) to test two aspects of climate change on Rana temporaria tadpole life-history traits and on tadpole-mediated nutrient pathways. On day 16 after hatching, we examined tadpole-mediated nutrient recycling by measuring tadpole nutrient excretion and egestion rates and tadpole body nutrient content. We estimated tadpole growth and development rates from hatching to emergence and measured emergent frog body size and body nutrient content. * Brownification increased total pond water nutrient availability and total pond water nitrogen (N) : phosphorous (P) ratios. Warming positively affected tadpole growth and development rates, whereas browning increased tadpole growth rate only under ambient temperatures. Emergent frog body P content decreased with warming, but only in the clear treatments. But despite these variations in body nutrient content, body stoichiometry remained within a relatively narrow stoichiometric range for both emergent frogs (P content: 1.4–1.8%, N content: 11.4–11.8% and carbon [C] content: 46.9–51.3%) and tadpoles (P content: 1.1–1.2%, N content: 10.1–11.7% and C content: 48.0–50.5%). Warming increased tadpole body P content and browning had a positive effect on tadpole body N content and tadpole N excretion rates, probably mediated by the increased pond water total N availability. * We conclude that warming and brownification will interact in changing aquatic consumer growth and body nutrient stoichiometry. In addition, warming has the potential to affect emergent frog body nutrient content and may thus affect nutrient transport from water to land. Last, by increasing pond water N availability, brownification appears to intensify consumer P limitation and thus amplify consumer-meditated N recycling.\n
\n\n\n\n \n\n \n \n \n \n \n Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment.\n \n \n \n\n\n \n Abbott, B. W.; Jones, J. B.; Schuur, E. A. G.; Chapin, F. S.; Bowden, W. B.; Bret-Harte, M. S.; Epstein, H. E.; Flannigan, M. D.; Harms, T. K.; Hollingsworth, T. N.; Mack, M. C.; McGuire, A. D.; Natali, S. M.; Rocha, A. V.; Tank, S. E.; Turetsky, M. R.; Vonk, J. E.; Wickland, K. P.; Aiken, G. R.; Alexander, H. D.; Amon, R. M. W.; Benscoter, B. W.; Bergeron, Y.; Bishop, K.; Blarquez, O.; Bond-Lamberty, B.; Breen, A. L.; Buffam, I.; Cai, Y.; Carcaillet, C.; Carey, S. K.; Chen, J. M.; Chen, H. Y. H.; Christensen, T. R.; Cooper, L. W.; Cornelissen, J. H. C.; de Groot, W. J.; DeLuca, T. H.; Dorrepaal, E.; Fetcher, N.; Finlay, J. C.; Forbes, B. C.; French, N. H. F.; Gauthier, S.; Girardin, M. P.; Goetz, S. J.; Goldammer, J. G.; Gough, L.; Grogan, P.; Guo, L.; Higuera, P. E.; Hinzman, L.; Hu, F. S.; Hugelius, G.; Jafarov, E. E.; Jandt, R.; Johnstone, J. F.; Karlsson, J.; Kasischke, E. S.; Kattner, G.; Kelly, R.; Keuper, F.; Kling, G. W.; Kortelainen, P.; Kouki, J.; Kuhry, P.; Laudon, H.; Laurion, I.; Macdonald, R. W.; Mann, P. J.; Martikainen, P. J.; McClelland, J. W.; Molau, U.; Oberbauer, S. F.; Olefeldt, D.; Pare, D.; Parisien, M.; Payette, S.; Peng, C.; Pokrovsky, O. S.; Rastetter, E. B.; Raymond, P. A.; Raynolds, M. K.; Rein, G.; Reynolds, J. F.; Robards, M.; Rogers, B. M.; Schaedel, C.; Schaefer, K.; Schmidt, I. K.; Shvidenko, A.; Sky, J.; Spencer, R. G. M.; Starr, G.; Striegl, R. G.; Teisserenc, R.; Tranvik, L. J.; Virtanen, T.; Welker, J. M.; and Zimov, S.\n\n\n \n\n\n\n Environmental Research Letters, 11(3): 034014. March 2016.\n 00014\n\n\n\n
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\n\n\n@article{abbott_biomass_2016,\n\ttitle = {Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment},\n\tvolume = {11},\n\tissn = {1748-9326},\n\tshorttitle = {Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire},\n\tdoi = {10.1088/1748-9326/11/3/034014},\n\tabstract = {As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75\\% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65\\%-85\\% of permafrost carbon release can still be avoided if human emissions are actively reduced.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Abbott, Benjamin W. and Jones, Jeremy B. and Schuur, Edward A. G. and Chapin, F. Stuart and Bowden, William B. and Bret-Harte, M. Syndonia and Epstein, Howard E. and Flannigan, Michael D. and Harms, Tamara K. and Hollingsworth, Teresa N. and Mack, Michelle C. and McGuire, A. David and Natali, Susan M. and Rocha, Adrian V. and Tank, Suzanne E. and Turetsky, Merritt R. and Vonk, Jorien E. and Wickland, Kimberly P. and Aiken, George R. and Alexander, Heather D. and Amon, Rainer M. W. and Benscoter, Brian W. and Bergeron, Yves and Bishop, Kevin and Blarquez, Olivier and Bond-Lamberty, Ben and Breen, Amy L. and Buffam, Ishi and Cai, Yihua and Carcaillet, Christopher and Carey, Sean K. and Chen, Jing M. and Chen, Han Y. H. and Christensen, Torben R. and Cooper, Lee W. and Cornelissen, J. Hans C. and de Groot, William J. and DeLuca, Thomas H. and Dorrepaal, Ellen and Fetcher, Ned and Finlay, Jacques C. and Forbes, Bruce C. and French, Nancy H. F. and Gauthier, Sylvie and Girardin, Martin P. and Goetz, Scott J. and Goldammer, Johann G. and Gough, Laura and Grogan, Paul and Guo, Laodong and Higuera, Philip E. and Hinzman, Larry and Hu, Feng Sheng and Hugelius, Gustaf and Jafarov, Elchin E. and Jandt, Randi and Johnstone, Jill F. and Karlsson, Jan and Kasischke, Eric S. and Kattner, Gerhard and Kelly, Ryan and Keuper, Frida and Kling, George W. and Kortelainen, Pirkko and Kouki, Jari and Kuhry, Peter and Laudon, Hjalmar and Laurion, Isabelle and Macdonald, Robie W. and Mann, Paul J. and Martikainen, Pertti J. and McClelland, James W. and Molau, Ulf and Oberbauer, Steven F. and Olefeldt, David and Pare, David and Parisien, Marc-Andre and Payette, Serge and Peng, Changhui and Pokrovsky, Oleg S. and Rastetter, Edward B. and Raymond, Peter A. and Raynolds, Martha K. and Rein, Guillermo and Reynolds, James F. and Robards, Martin and Rogers, Brendan M. and Schaedel, Christina and Schaefer, Kevin and Schmidt, Inger K. and Shvidenko, Anatoly and Sky, Jasper and Spencer, Robert G. M. and Starr, Gregory and Striegl, Robert G. and Teisserenc, Roman and Tranvik, Lars J. and Virtanen, Tarmo and Welker, Jeffrey M. and Zimov, Sergei},\n\tmonth = mar,\n\tyear = {2016},\n\tnote = {00014},\n\tkeywords = {\\#nosource, Arctic, Boreal forest, Ecosystems, arctic tundra, boreal, climate-change, coastal erosion, dissolved organic carbon, fire, interior alaska, nitrogen deposition, particulate organic carbon, permafrost carbon, sequestration, storage, vulnerability, wildfire},\n\tpages = {034014},\n}\n\n\n\n\n\n As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.\n
\n\n\n\n \n\n \n \n \n \n \n \n Is the subarctic landscape still a carbon sink? Evidence from a detailed catchment balance.\n \n \n \n \n\n\n \n Lundin, E. J.; Klaminder, J.; Giesler, R.; Persson, A.; Olefeldt, D.; Heliasz, M.; Christensen, T. R.; and Karlsson, J.\n\n\n \n\n\n\n Geophysical Research Letters, 43(5): 2015GL066970. March 2016.\n 00001\n\n\n\n
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\n\n\n@article{lundin_is_2016,\n\ttitle = {Is the subarctic landscape still a carbon sink? {Evidence} from a detailed catchment balance},\n\tvolume = {43},\n\tissn = {1944-8007},\n\tshorttitle = {Is the subarctic landscape still a carbon sink?},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/2015GL066970/abstract},\n\tdoi = {10.1002/2015GL066970},\n\tabstract = {Climate warming raises the question whether high-latitude landscape still function as net carbon (C) sinks. By compiling an integrated C balance for an intensely studied subarctic catchment, we show that this catchment's C balance is not likely to be a strong current sink of C, a commonly held assumption. In fact, it is more plausible (71\\% probability) that the studied catchment functions as a C source (−11 ± 20 g C m−2 yr−1). Analyses of individual fluxes indicate that soil and aquatic C losses offset C sequestering in other landscape components (e.g., peatlands and aboveground forest biomass). Our results stress the importance of fully integrated catchment C balance estimates and highlight the importance of upland soils and their interaction with the aquatic network for the catchment C balance.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-06},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Lundin, Erik J. and Klaminder, Jonatan and Giesler, Reiner and Persson, Andreas and Olefeldt, David and Heliasz, Michal and Christensen, Torben R. and Karlsson, Jan},\n\tmonth = mar,\n\tyear = {2016},\n\tnote = {00001},\n\tkeywords = {\\#nosource, 0428 Carbon cycling, aquatic ecosystems, carbon balance, carbon cycling, sink, source, subarctic, terrestrial ecosystems},\n\tpages = {2015GL066970},\n}\n\n\n\n\n\n Climate warming raises the question whether high-latitude landscape still function as net carbon (C) sinks. By compiling an integrated C balance for an intensely studied subarctic catchment, we show that this catchment's C balance is not likely to be a strong current sink of C, a commonly held assumption. In fact, it is more plausible (71% probability) that the studied catchment functions as a C source (−11 ± 20 g C m−2 yr−1). Analyses of individual fluxes indicate that soil and aquatic C losses offset C sequestering in other landscape components (e.g., peatlands and aboveground forest biomass). Our results stress the importance of fully integrated catchment C balance estimates and highlight the importance of upland soils and their interaction with the aquatic network for the catchment C balance.\n
\n\n\n\n \n\n \n \n \n \n \n Do warming and humic river runoff alter the metabolic balance of lake ecosystems?.\n \n \n \n\n\n \n Rodriguez, P.; Byström, P.; Geibrink, E.; Hedström, P.; Vasconcelos, F. R.; and Karlsson, J.\n\n\n \n\n\n\n Aquatic Sciences, 78(4): 717–725. October 2016.\n 00003\n\n\n\n
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\n\n\n@article{rodriguez_warming_2016,\n\ttitle = {Do warming and humic river runoff alter the metabolic balance of lake ecosystems?},\n\tvolume = {78},\n\tissn = {1015-1621},\n\tdoi = {10.1007/s00027-015-0463-y},\n\tabstract = {Global warming is expected to influence lake gross primary production (GPP) and ecosystem respiration (R) by increasing water temperature and terrestrial export of organic material and inorganic nutrients from the catchment. We experimentally tested the effects of warming (3 A degrees C) and natural humic river runoff, separately and in combination, on habitat-specific and whole ecosystem net ecosystem production (NEP = GPP - R) in replicated large scale (136 m(3)) experimental pond ecosystems over one open water season. Pelagic NEP was reduced by warming and increased with humic river water addition. Littoral NEP (benthos, macrophytes, periphyton) showed an opposite pattern with increasing NEP following warming and decreasing NEP following humic river water addition. These changes were a result of changes in GPP with warming (negative in pelagic, positive in littoral) and with humic water addition (positive in pelagic, negative in littoral), while no effects were observed on pelagic respiration. As a result of the counteracting effects on NEP in pelagic and littoral habitats, whole ecosystem NEP was not affected by the treatments. The study suggests that climate mediated changes in temperature and river runoff have relatively small effects on the overall metabolic balance of shallow aquatic ecosystems but there may be large habitat-specific effects.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Rodriguez, Patricia and Byström, Pär and Geibrink, Erik and Hedström, Per and Vasconcelos, Francisco Rivera and Karlsson, Jan},\n\tmonth = oct,\n\tyear = {2016},\n\tnote = {00003},\n\tkeywords = {\\#nosource, Humic river runoff, Littoral habitat, Pelagic habitat, Warming, Whole ecosystem metabolism, bacterial, climate, communities, cycle, dioxide, dissolved organic-carbon, eutrophication, exchange, linking, nutrient addition},\n\tpages = {717--725},\n}\n\n\n\n\n\n Global warming is expected to influence lake gross primary production (GPP) and ecosystem respiration (R) by increasing water temperature and terrestrial export of organic material and inorganic nutrients from the catchment. We experimentally tested the effects of warming (3 A degrees C) and natural humic river runoff, separately and in combination, on habitat-specific and whole ecosystem net ecosystem production (NEP = GPP - R) in replicated large scale (136 m(3)) experimental pond ecosystems over one open water season. Pelagic NEP was reduced by warming and increased with humic river water addition. Littoral NEP (benthos, macrophytes, periphyton) showed an opposite pattern with increasing NEP following warming and decreasing NEP following humic river water addition. These changes were a result of changes in GPP with warming (negative in pelagic, positive in littoral) and with humic water addition (positive in pelagic, negative in littoral), while no effects were observed on pelagic respiration. As a result of the counteracting effects on NEP in pelagic and littoral habitats, whole ecosystem NEP was not affected by the treatments. The study suggests that climate mediated changes in temperature and river runoff have relatively small effects on the overall metabolic balance of shallow aquatic ecosystems but there may be large habitat-specific effects.\n
\n\n\n\n \n\n \n \n \n \n \n Asymmetrical competition between aquatic primary producers in a warmer and browner world.\n \n \n \n\n\n \n Vasconcelos, F. R.; Diehl, S.; Rodriguez, P.; Hedström, P.; Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Ecology, 97(10): 2580–2592. October 2016.\n \n\n\n\n
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\n\n\n@article{vasconcelos_asymmetrical_2016,\n\ttitle = {Asymmetrical competition between aquatic primary producers in a warmer and browner world},\n\tvolume = {97},\n\tissn = {0012-9658},\n\tdoi = {10.1002/ecy.1487},\n\tabstract = {In shallow lakes, pelagic and benthic producers engage in spatially asymmetrical resource competition. Pelagic producers intercept the flux of light to the benthic habitat and benthic producers intercept the flux of sediment-derived nutrients to the pelagic habitat. In boreal and subarctic regions, climate change is affecting this interaction both directly through warming and indirectly through increased loading with colored dissolved organic matter (cDOM) from the catchment (brownification). We use a dynamical ecosystem model to explore the consequences of these changing environmental conditions for lake primary production and compare model predictions with the results of an experiment in which we manipulated water temperature and cDOM supply in a 2x2 factorial design. The experiment was performed in field mesocosms large enough to harbor reproducing fish populations and was run over an entire growing season. In agreement with model predictions, benthic algal production and biomass declined and pelagic algal production and biomass increased with browning. Pelagic nutrient concentrations diverged over time between low and high cDOM treatments, suggesting that browning alleviated pelagic algal nutrient limitation by shading benthic competitors and preventing them from intercepting the release of nutrients from the sediment. Warming considerably reduced benthic and pelagic algal production as well as pelagic algalbiomass and total phosphorus. The warming results are only in partial accordance with model expectations, but can be explained by an indirectly inferred, positive response of macrophyte production (which was not included in the model) to warming. Our study suggests that lake ecosystem responses to climate change are mediated by cross-habitat feedbacks between benthic and pelagic producers.},\n\tlanguage = {English},\n\tnumber = {10},\n\tjournal = {Ecology},\n\tauthor = {Vasconcelos, Francisco Rivera and Diehl, Sebastian and Rodriguez, Patricia and Hedström, Per and Karlsson, Jan and Byström, Pär},\n\tmonth = oct,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Warming, algal biomass, asymmetry, benthic, boreal, brownification, climate-change, dissolved organic-carbon, events, lake ecosystems, light, metabolic balance, pelagic, resource competition, resource competition, shallow lake, temperature-dependence},\n\tpages = {2580--2592},\n}\n\n\n\n\n\n In shallow lakes, pelagic and benthic producers engage in spatially asymmetrical resource competition. Pelagic producers intercept the flux of light to the benthic habitat and benthic producers intercept the flux of sediment-derived nutrients to the pelagic habitat. In boreal and subarctic regions, climate change is affecting this interaction both directly through warming and indirectly through increased loading with colored dissolved organic matter (cDOM) from the catchment (brownification). We use a dynamical ecosystem model to explore the consequences of these changing environmental conditions for lake primary production and compare model predictions with the results of an experiment in which we manipulated water temperature and cDOM supply in a 2x2 factorial design. The experiment was performed in field mesocosms large enough to harbor reproducing fish populations and was run over an entire growing season. In agreement with model predictions, benthic algal production and biomass declined and pelagic algal production and biomass increased with browning. Pelagic nutrient concentrations diverged over time between low and high cDOM treatments, suggesting that browning alleviated pelagic algal nutrient limitation by shading benthic competitors and preventing them from intercepting the release of nutrients from the sediment. Warming considerably reduced benthic and pelagic algal production as well as pelagic algalbiomass and total phosphorus. The warming results are only in partial accordance with model expectations, but can be explained by an indirectly inferred, positive response of macrophyte production (which was not included in the model) to warming. Our study suggests that lake ecosystem responses to climate change are mediated by cross-habitat feedbacks between benthic and pelagic producers.\n
\n\n\n\n \n\n \n \n \n \n \n \n Size-related effects of physical factors on phytoplankton communities.\n \n \n \n \n\n\n \n Portalier, S. M. J.; Cherif, M.; Zhang, L.; Fussmann, G. F.; and Loreau, M.\n\n\n \n\n\n\n Ecological Modelling, 323: 41–50. March 2016.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{portalier_size-related_2016,\n\ttitle = {Size-related effects of physical factors on phytoplankton communities},\n\tvolume = {323},\n\tissn = {0304-3800},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0304380015005554},\n\tdoi = {10.1016/j.ecolmodel.2015.12.003},\n\tabstract = {Phytoplankton communities are influenced by light availability. Therefore, one factor promoting phytoplankton species persistence is their ability to stay within the euphotic zone. This ability is determined by the interplay between species mass, buoyancy and dispersion, which are driven by physical factors. In this study, we investigate how these physical factors and light-use efficiency, all correlated with cell size, influence species persistence. Our model shows, first, that species can persist only within a size-dependent range of turbulence strength. The minimal level of turbulence required for persistence increases drastically with cell size, while all species reach similar maximal levels of turbulence. Second, the maximal water column depth allowing persistence is also size-dependent: large cells show a maximal depth at both low and high turbulence strength, while small cells show this pattern only at high turbulence strength. This study emphasizes the importance of the physical medium in ecosystems and its interplay with cell size for phytoplankton dynamics and bloom condition.},\n\turldate = {2017-05-27},\n\tjournal = {Ecological Modelling},\n\tauthor = {Portalier, Sébastien M. J. and Cherif, Mehdi and Zhang, Lai and Fussmann, Gregor F. and Loreau, Michel},\n\tmonth = mar,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Critical depth, Light limitation, Phytoplankton bloom, Turbulence},\n\tpages = {41--50},\n}\n\n\n\n\n\n Phytoplankton communities are influenced by light availability. Therefore, one factor promoting phytoplankton species persistence is their ability to stay within the euphotic zone. This ability is determined by the interplay between species mass, buoyancy and dispersion, which are driven by physical factors. In this study, we investigate how these physical factors and light-use efficiency, all correlated with cell size, influence species persistence. Our model shows, first, that species can persist only within a size-dependent range of turbulence strength. The minimal level of turbulence required for persistence increases drastically with cell size, while all species reach similar maximal levels of turbulence. Second, the maximal water column depth allowing persistence is also size-dependent: large cells show a maximal depth at both low and high turbulence strength, while small cells show this pattern only at high turbulence strength. This study emphasizes the importance of the physical medium in ecosystems and its interplay with cell size for phytoplankton dynamics and bloom condition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Potential for Local Fertilization: A Benthocosm Test of Long-Term and Short-Term Effects of Mussel Excretion on the Plankton.\n \n \n \n \n\n\n \n Cherif, M.; Granados, M.; Duffy, S.; Robert, P.; Péquin, B.; Mohit, V.; McKindsey, C. W.; Archambault, P.; Myrand, B.; Lovejoy, C.; Tremblay, R.; Plourde, S.; and Fussmann, G. F.\n\n\n \n\n\n\n PLOS ONE, 11(6): e0156411. June 2016.\n \n\n\n\n
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\n\n\n@article{cherif_potential_2016,\n\ttitle = {Potential for {Local} {Fertilization}: {A} {Benthocosm} {Test} of {Long}-{Term} and {Short}-{Term} {Effects} of {Mussel} {Excretion} on the {Plankton}},\n\tvolume = {11},\n\tissn = {1932-6203},\n\tshorttitle = {Potential for {Local} {Fertilization}},\n\turl = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0156411},\n\tdoi = {10.1371/journal.pone.0156411},\n\tabstract = {Mussel aquaculture has expanded worldwide and it is important to assess its impact on the water column and the planktonic food web to determine the sustainability of farming practices. Mussel farming may affect the planktonic food web indirectly by excreting bioavailable nutrients in the water column (a short-term effect) or by increasing nutrient effluxes from biodeposit-enriched sediments (a long-term effect). We tested both of these indirect effects in a lagoon by using plankton-enclosing benthocosms that were placed on the bottom of a shallow lagoon either inside of a mussel farm or at reference sites with no history of aquaculture. At each site, half of the benthocosms were enriched with seawater that had held mussels (excretion treatment), the other half received non-enriched seawater as a control treatment. We monitored nutrients ([PO43-] and [NH4+]), dissolved oxygen and plankton components (bacteria, the phytoplankton and the zooplankton) over 5 days. We found a significant relationship between long-term accumulation of mussel biodeposits in sediments, water-column nutrient concentrations and plankton growth. Effects of mussel excretion were not detected, too weak to be significant given the spatial and temporal variability observed in the lagoon. Effects of mussels on the water column are thus likely to be coupled to benthic processes in such semi-enclosed water bodies.},\n\tnumber = {6},\n\turldate = {2017-05-27},\n\tjournal = {PLOS ONE},\n\tauthor = {Cherif, Mehdi and Granados, Monica and Duffy, Sean and Robert, Pauline and Péquin, Bérangère and Mohit, Vani and McKindsey, Christopher W. and Archambault, Philippe and Myrand, Bruno and Lovejoy, Connie and Tremblay, Réjean and Plourde, Stéphane and Fussmann, Gregor F.},\n\tmonth = jun,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Lagoons, Mussels, Sediment, Water columns, excretion, phytoplankton, plankton, zooplankton},\n\tpages = {e0156411},\n}\n\n\n\n\n\n Mussel aquaculture has expanded worldwide and it is important to assess its impact on the water column and the planktonic food web to determine the sustainability of farming practices. Mussel farming may affect the planktonic food web indirectly by excreting bioavailable nutrients in the water column (a short-term effect) or by increasing nutrient effluxes from biodeposit-enriched sediments (a long-term effect). We tested both of these indirect effects in a lagoon by using plankton-enclosing benthocosms that were placed on the bottom of a shallow lagoon either inside of a mussel farm or at reference sites with no history of aquaculture. At each site, half of the benthocosms were enriched with seawater that had held mussels (excretion treatment), the other half received non-enriched seawater as a control treatment. We monitored nutrients ([PO43-] and [NH4+]), dissolved oxygen and plankton components (bacteria, the phytoplankton and the zooplankton) over 5 days. We found a significant relationship between long-term accumulation of mussel biodeposits in sediments, water-column nutrient concentrations and plankton growth. Effects of mussel excretion were not detected, too weak to be significant given the spatial and temporal variability observed in the lagoon. Effects of mussels on the water column are thus likely to be coupled to benthic processes in such semi-enclosed water bodies.\n
\n\n\n\n \n\n \n \n \n \n \n \n Methane oxidation at the water-ice interface of an ice-covered lake.\n \n \n \n \n\n\n \n Ricão Canelhas, M.; Denfeld, B. A.; Weyhenmeyer, G. A.; Bastviken, D.; and Bertilsson, S.\n\n\n \n\n\n\n Limnology and Oceanography, 61(S1): S78–S90. November 2016.\n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{ricao_canelhas_methane_2016,\n\ttitle = {Methane oxidation at the water-ice interface of an ice-covered lake},\n\tvolume = {61},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/lno.10288/abstract},\n\tdoi = {10.1002/lno.10288},\n\tabstract = {Lakes are important components of the global methane (CH4) cycle. In seasonally ice-covered lakes, CH4 transported by ebullition (bubbling) from anoxic sediments gets trapped at the water-ice interface. If not oxidized by methane-oxidizing bacteria (MOB), this can potentially lead to high episodic CH4 emissions at ice-melt. To understand the fate of CH4 trapped below ice, we measured depth-distributions of CH4 concentrations in the water column near bubbles trapped below ice in Lake Erken. We also performed a 21 d incubation experiment at low temperature (2.3 ± 0.2°C) to investigate the potential for CH4 oxidation. During most sampling occasions, we found steep CH4 concentration gradients just below the ice with a 13-fold decrease from the surface to a depth of 20 cm. In vitro incubations revealed that CH4 oxidation can occur at low temperatures typical for the water-ice interface. CH4 oxidation was observed as a significant decrease in CH4 concentration, a significant increase in stable isotope 13C signature, and an increase in MOB during the incubation. Thus, CH4 accumulating in the top 20 cm of the water column, fed by diffusion from CH4 in trapped bubbles, may fuel significant CH4 oxidation. Since northern latitude lakes can be ice-covered for many months of the year and significant amounts of CH4 accumulate below the ice, the extent of CH4 oxidation under these low temperature-conditions is important for understanding the potential CH4 emissions to the atmosphere during ice-melt.},\n\tlanguage = {en},\n\tnumber = {S1},\n\turldate = {2017-05-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Ricão Canelhas, Monica and Denfeld, Blaize A. and Weyhenmeyer, Gesa A. and Bastviken, David and Bertilsson, Stefan},\n\tmonth = nov,\n\tyear = {2016},\n\tkeywords = {\\#nosource},\n\tpages = {S78--S90},\n}\n\n\n\n\n\n Lakes are important components of the global methane (CH4) cycle. In seasonally ice-covered lakes, CH4 transported by ebullition (bubbling) from anoxic sediments gets trapped at the water-ice interface. If not oxidized by methane-oxidizing bacteria (MOB), this can potentially lead to high episodic CH4 emissions at ice-melt. To understand the fate of CH4 trapped below ice, we measured depth-distributions of CH4 concentrations in the water column near bubbles trapped below ice in Lake Erken. We also performed a 21 d incubation experiment at low temperature (2.3 ± 0.2°C) to investigate the potential for CH4 oxidation. During most sampling occasions, we found steep CH4 concentration gradients just below the ice with a 13-fold decrease from the surface to a depth of 20 cm. In vitro incubations revealed that CH4 oxidation can occur at low temperatures typical for the water-ice interface. CH4 oxidation was observed as a significant decrease in CH4 concentration, a significant increase in stable isotope 13C signature, and an increase in MOB during the incubation. Thus, CH4 accumulating in the top 20 cm of the water column, fed by diffusion from CH4 in trapped bubbles, may fuel significant CH4 oxidation. Since northern latitude lakes can be ice-covered for many months of the year and significant amounts of CH4 accumulate below the ice, the extent of CH4 oxidation under these low temperature-conditions is important for understanding the potential CH4 emissions to the atmosphere during ice-melt.\n
\n\n\n\n \n\n \n \n \n \n \n \n Constraints on methane oxidation in ice-covered boreal lakes.\n \n \n \n \n\n\n \n Denfeld, B. A.; Ricão Canelhas, M.; Weyhenmeyer, G. A.; Bertilsson, S.; Eiler, A.; and Bastviken, D.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 121(7): 2016JG003382. July 2016.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{denfeld_constraints_2016,\n\ttitle = {Constraints on methane oxidation in ice-covered boreal lakes},\n\tvolume = {121},\n\tissn = {2169-8961},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/2016JG003382/abstract},\n\tdoi = {10.1002/2016JG003382},\n\tabstract = {Boreal lakes can be ice covered for a substantial portion of the year at which time methane (CH4) can accumulate below ice. The amount of CH4 emitted at ice melt is partially determined by the interplay between CH4 production and CH4 oxidation, performed by methane-oxidizing bacteria (MOB). Yet the balance between oxidation and emission and the potential for CH4 oxidation in various lakes during winter is largely unknown. To address this, we performed incubations at 2°C to screen for wintertime CH4 oxidation potential in seven lakes. Results showed that CH4 oxidation was restricted to three lakes, where the phosphate concentrations were highest. Molecular analyses revealed that MOB were initially detected in all lakes, although an increase in type I MOB only occurred in the three lake water incubations where oxidation could be observed. Accordingly, the increase in CO2 was on average 5 times higher in these three lake water incubations. For one lake where no oxidation was measured, we tested if temperature and CH4 availability could trigger CH4 oxidation. However, regardless of incubation temperatures and CH4 concentrations, ranging from 2 to 20°C and 1–500 μM, respectively, no oxidation was observed. Our study indicates that some lakes with active wintertime CH4 oxidation may have low emissions during ice melt, while other and particularly nutrient poor lakes may accumulate large amounts of CH4 below ice that, in the absence of CH4 oxidation, will be emitted following ice melt. This variability in CH4 oxidation rates between lakes needs to be accounted for in large-scale CH4 emission estimates.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-05-27},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Denfeld, Blaize A. and Ricão Canelhas, Monica and Weyhenmeyer, Gesa A. and Bertilsson, Stefan and Eiler, Alexander and Bastviken, David},\n\tmonth = jul,\n\tyear = {2016},\n\tkeywords = {\\#nosource, 0458 Limnology, 4806 Carbon cycling, 4930 Greenhouse gases, Methanotrophs, ice-covered lakes, methane oxidation},\n\tpages = {2016JG003382},\n}\n\n\n\n\n\n Boreal lakes can be ice covered for a substantial portion of the year at which time methane (CH4) can accumulate below ice. The amount of CH4 emitted at ice melt is partially determined by the interplay between CH4 production and CH4 oxidation, performed by methane-oxidizing bacteria (MOB). Yet the balance between oxidation and emission and the potential for CH4 oxidation in various lakes during winter is largely unknown. To address this, we performed incubations at 2°C to screen for wintertime CH4 oxidation potential in seven lakes. Results showed that CH4 oxidation was restricted to three lakes, where the phosphate concentrations were highest. Molecular analyses revealed that MOB were initially detected in all lakes, although an increase in type I MOB only occurred in the three lake water incubations where oxidation could be observed. Accordingly, the increase in CO2 was on average 5 times higher in these three lake water incubations. For one lake where no oxidation was measured, we tested if temperature and CH4 availability could trigger CH4 oxidation. However, regardless of incubation temperatures and CH4 concentrations, ranging from 2 to 20°C and 1–500 μM, respectively, no oxidation was observed. Our study indicates that some lakes with active wintertime CH4 oxidation may have low emissions during ice melt, while other and particularly nutrient poor lakes may accumulate large amounts of CH4 below ice that, in the absence of CH4 oxidation, will be emitted following ice melt. This variability in CH4 oxidation rates between lakes needs to be accounted for in large-scale CH4 emission estimates.\n
\n\n\n\n \n\n \n \n \n \n \n \n Regional Variability and Drivers of Below Ice CO2 in Boreal and Subarctic Lakes.\n \n \n \n \n\n\n \n Denfeld, B. A.; Kortelainen, P.; Rantakari, M.; Sobek, S.; and Weyhenmeyer, G. A.\n\n\n \n\n\n\n Ecosystems, 19(3): 461–476. April 2016.\n \n\n\n\n
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\n\n\n@article{denfeld_regional_2016,\n\ttitle = {Regional {Variability} and {Drivers} of {Below} {Ice} {CO2} in {Boreal} and {Subarctic} {Lakes}},\n\tvolume = {19},\n\tissn = {1432-9840, 1435-0629},\n\turl = {https://link.springer.com/article/10.1007/s10021-015-9944-z},\n\tdoi = {10.1007/s10021-015-9944-z},\n\tabstract = {Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO2) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO2 variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO2 across the 506 lakes. Together, lake morphometry and water chemistry explained 53\\% of the site-to-site variation in below ice pCO2. Regional climate (including ice cover duration) and latitude only explained 7\\% of the variation in below ice pCO2. Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-05-27},\n\tjournal = {Ecosystems},\n\tauthor = {Denfeld, Blaize A. and Kortelainen, Pirkko and Rantakari, Miitta and Sobek, Sebastian and Weyhenmeyer, Gesa A.},\n\tmonth = apr,\n\tyear = {2016},\n\tkeywords = {\\#nosource},\n\tpages = {461--476},\n}\n\n\n\n\n\n Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO2) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO2 variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO2 across the 506 lakes. Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice pCO2. Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice pCO2. Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n The role of sediments in the carbon budget of a small boreal lake.\n \n \n \n \n\n\n \n Chmiel, H. E.; Kokic, J.; Denfeld, B. A.; Einarsdóttir, K.; Wallin, M. B.; Koehler, B.; Isidorova, A.; Bastviken, D.; Ferland, M.; and Sobek, S.\n\n\n \n\n\n\n Limnology and Oceanography, 61(5): 1814–1825. September 2016.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{chmiel_role_2016,\n\ttitle = {The role of sediments in the carbon budget of a small boreal lake},\n\tvolume = {61},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/lno.10336/abstract},\n\tdoi = {10.1002/lno.10336},\n\tabstract = {We investigated the role of lake sediments as carbon (C) source and sink in the annual C budget of a small (0.07 km2) and shallow (mean depth, 3.4 m), humic lake in boreal Sweden. Organic carbon (OC) burial and mineralization in the sediments were quantified from 210Pb-dated sediment and laboratory sediment incubation experiments, respectively. Burial and mineralization rates were then upscaled to the entire basin and to one whole year using sediment thickness derived from sub-bottom profiling, basin morphometry, and water column monitoring data of temperature and oxygen concentration. Furthermore, catchment C import, open water metabolism, photochemical mineralization as well as carbon dioxide (CO2) and methane (CH4) emissions to the atmosphere were quantified to relate sediment processes to other lake C fluxes. We found that on a whole-basin and annual scale, sediment OC mineralization was three times larger than OC burial, and contributed about 16\\% to the annual CO2 emission. Other contributions to CO2 emission were water column metabolism (31\\%), photochemical mineralization (6\\%), and catchment imports via inlet streams and inflow of shallow groundwater (22\\%). The remainder (25\\%) could not be explained by our flux calculations, but was most likely attributed to an underestimation in groundwater inflow. We conclude that on an annual and whole-basin scale (1) sediment OC mineralization dominated over OC burial, (2) water column OC mineralization contributed more to lake CO2 emission than sediment OC mineralization, and (3) catchment import of C to the lake was greater than lake-internal C cycling.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-05-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Chmiel, Hannah E. and Kokic, Jovana and Denfeld, Blaize A. and Einarsdóttir, Karólína and Wallin, Marcus B. and Koehler, Birgit and Isidorova, Anastasija and Bastviken, David and Ferland, Marie-Ève and Sobek, Sebastian},\n\tmonth = sep,\n\tyear = {2016},\n\tkeywords = {\\#nosource},\n\tpages = {1814--1825},\n}\n\n\n\n\n\n We investigated the role of lake sediments as carbon (C) source and sink in the annual C budget of a small (0.07 km2) and shallow (mean depth, 3.4 m), humic lake in boreal Sweden. Organic carbon (OC) burial and mineralization in the sediments were quantified from 210Pb-dated sediment and laboratory sediment incubation experiments, respectively. Burial and mineralization rates were then upscaled to the entire basin and to one whole year using sediment thickness derived from sub-bottom profiling, basin morphometry, and water column monitoring data of temperature and oxygen concentration. Furthermore, catchment C import, open water metabolism, photochemical mineralization as well as carbon dioxide (CO2) and methane (CH4) emissions to the atmosphere were quantified to relate sediment processes to other lake C fluxes. We found that on a whole-basin and annual scale, sediment OC mineralization was three times larger than OC burial, and contributed about 16% to the annual CO2 emission. Other contributions to CO2 emission were water column metabolism (31%), photochemical mineralization (6%), and catchment imports via inlet streams and inflow of shallow groundwater (22%). The remainder (25%) could not be explained by our flux calculations, but was most likely attributed to an underestimation in groundwater inflow. We conclude that on an annual and whole-basin scale (1) sediment OC mineralization dominated over OC burial, (2) water column OC mineralization contributed more to lake CO2 emission than sediment OC mineralization, and (3) catchment import of C to the lake was greater than lake-internal C cycling.\n
\n\n\n\n \n\n \n \n \n \n \n \n GABAergic anxiolytic drug in water increases migration behaviour in salmon.\n \n \n \n \n\n\n \n Hellström, G.; Klaminder, J.; Finn, F.; Persson, L.; Alanärä, A.; Jonsson, M.; Fick, J.; and Brodin, T.\n\n\n \n\n\n\n Nature Communications, 7: 13460. December 2016.\n 00009\n\n\n\n
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\n\n\n@article{hellstrom_gabaergic_2016,\n\ttitle = {{GABAergic} anxiolytic drug in water increases migration behaviour in salmon},\n\tvolume = {7},\n\tcopyright = {© 2016 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.},\n\tissn = {2041-1723},\n\turl = {http://www.nature.com/ncomms/2016/161206/ncomms13460/full/ncomms13460.html},\n\tdoi = {10.1038/ncomms13460},\n\tabstract = {Fish migration is influenced by various environmental factors such as chemicals in water. Here, Hellstrom et al. show that an anxiolytic drug in the benzodiazepine family, oxazepam, can promote migratory behaviour of Atlantic salmon smolts in both laboratory setting and river tributary in Sweden.},\n\tlanguage = {en},\n\turldate = {2016-12-11},\n\tjournal = {Nature Communications},\n\tauthor = {Hellström, Gustav and Klaminder, Jonatan and Finn, Fia and Persson, Lo and Alanärä, Anders and Jonsson, Micael and Fick, Jerker and Brodin, Tomas},\n\tmonth = dec,\n\tyear = {2016},\n\tnote = {00009},\n\tkeywords = {\\#nosource},\n\tpages = {13460},\n}\n\n\n\n\n\n Fish migration is influenced by various environmental factors such as chemicals in water. Here, Hellstrom et al. show that an anxiolytic drug in the benzodiazepine family, oxazepam, can promote migratory behaviour of Atlantic salmon smolts in both laboratory setting and river tributary in Sweden.\n
\n\n\n\n \n\n \n \n \n \n \n \n Past and present biophysical redundancy of countries as a buffer to changes in food supply.\n \n \n \n \n\n\n \n Fader, M.; Rulli, M. C.; Carr, J.; Dell’Angelo, J.; D’Odorico, P.; Gephart, J. A.; Kummu, M.; Magliocca, N.; Porkka, M.; Prell, C.; Puma, M. J.; Zak Ratajczak; Seekell, D. A.; Suweis, S.; and Tavoni, A.\n\n\n \n\n\n\n Environmental Research Letters, 11(5): 055008. 2016.\n 00005\n\n\n\n
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\n\n\n@article{fader_past_2016,\n\ttitle = {Past and present biophysical redundancy of countries as a buffer to changes in food supply},\n\tvolume = {11},\n\tissn = {1748-9326},\n\turl = {http://stacks.iop.org/1748-9326/11/i=5/a=055008},\n\tdoi = {10.1088/1748-9326/11/5/055008},\n\tabstract = {Spatially diverse trends in population growth, climate change, industrialization, urbanization and economic development are expected to change future food supply and demand. These changes may affect the suitability of land for food production, implying elevated risks especially for resource-constrained, food-importing countries. We present the evolution of biophysical redundancy for agricultural production at country level, from 1992 to 2012. Biophysical redundancy, defined as unused biotic and abiotic environmental resources, is represented by the potential food production of ‘spare land’, available water resources (i.e., not already used for human activities), as well as production increases through yield gap closure on cultivated areas and potential agricultural areas. In 2012, the biophysical redundancy of 75 (48) countries, mainly in North Africa, Western Europe, the Middle East and Asia, was insufficient to produce the caloric nutritional needs for at least 50\\% (25\\%) of their population during a year. Biophysical redundancy has decreased in the last two decades in 102 out of 155 countries, 11 of these went from high to limited redundancy, and nine of these from limited to very low redundancy. Although the variability of the drivers of change across different countries is high, improvements in yield and population growth have a clear impact on the decreases of redundancy towards the very low redundancy category. We took a more detailed look at countries classified as ‘Low Income Economies (LIEs)’ since they are particularly vulnerable to domestic or external food supply changes, due to their limited capacity to offset for food supply decreases with higher purchasing power on the international market. Currently, nine LIEs have limited or very low biophysical redundancy. Many of these showed a decrease in redundancy over the last two decades, which is not always linked with improvements in per capita food availability.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2016-05-27},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Fader, Marianela and Rulli, Maria Cristina and Carr, Joel and Dell’Angelo, Jampel and D’Odorico, Paolo and Gephart, Jessica A. and Kummu, Matti and Magliocca, Nicholas and Porkka, Miina and Prell, Christina and Puma, Michael J. and {Zak Ratajczak} and Seekell, David A. and Suweis, Samir and Tavoni, Alessandro},\n\tyear = {2016},\n\tnote = {00005},\n\tkeywords = {\\#nosource},\n\tpages = {055008},\n}\n\n\n\n\n\n Spatially diverse trends in population growth, climate change, industrialization, urbanization and economic development are expected to change future food supply and demand. These changes may affect the suitability of land for food production, implying elevated risks especially for resource-constrained, food-importing countries. We present the evolution of biophysical redundancy for agricultural production at country level, from 1992 to 2012. Biophysical redundancy, defined as unused biotic and abiotic environmental resources, is represented by the potential food production of ‘spare land’, available water resources (i.e., not already used for human activities), as well as production increases through yield gap closure on cultivated areas and potential agricultural areas. In 2012, the biophysical redundancy of 75 (48) countries, mainly in North Africa, Western Europe, the Middle East and Asia, was insufficient to produce the caloric nutritional needs for at least 50% (25%) of their population during a year. Biophysical redundancy has decreased in the last two decades in 102 out of 155 countries, 11 of these went from high to limited redundancy, and nine of these from limited to very low redundancy. Although the variability of the drivers of change across different countries is high, improvements in yield and population growth have a clear impact on the decreases of redundancy towards the very low redundancy category. We took a more detailed look at countries classified as ‘Low Income Economies (LIEs)’ since they are particularly vulnerable to domestic or external food supply changes, due to their limited capacity to offset for food supply decreases with higher purchasing power on the international market. Currently, nine LIEs have limited or very low biophysical redundancy. Many of these showed a decrease in redundancy over the last two decades, which is not always linked with improvements in per capita food availability.\n
\n\n\n\n \n\n \n \n \n \n \n Upscaling behavioural studies to the field using acoustic telemetry.\n \n \n \n\n\n \n Hellström, G.; Klaminder, J.; Jonsson, M.; Fick, J.; and Brodin, T.\n\n\n \n\n\n\n Aquatic Toxicology (Amsterdam, Netherlands), 170: 384–389. January 2016.\n 00006 \n\n\n\n
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\n\n\n@article{hellstrom_upscaling_2016,\n\ttitle = {Upscaling behavioural studies to the field using acoustic telemetry},\n\tvolume = {170},\n\tissn = {1879-1514},\n\tdoi = {10.1016/j.aquatox.2015.11.005},\n\tabstract = {Laboratory-based behavioural assays are often used in ecotoxicological studies to assess the environmental risk of aquatic contaminants. While results from such laboratory-based risk assessments may be difficult to extrapolate to natural environments, technological advancements over the past decade now make it possible to perform risk assessments through detailed studies of exposed individuals in natural settings. Acoustic telemetry is a technology to monitor movement and behaviour of aquatic organism in oceans, lakes, and rivers. The technology allows for tracking of multiple individuals simultaneously with very high temporal and spatial resolution, with the option to incorporate sensors to measure various physiological and environmental parameters. Although frequently used in fisheries research, aquatic ecotoxicology has been slow to adopt acoustic telemetry as a tool in field-based studies. This mini-review intends to introduce acoustic telemetry to aquatic ecotoxicologists, focusing on the potential of the technology to bridge the gap between laboratory assays and natural behaviours when making toxicological risk assessments.},\n\tlanguage = {eng},\n\tjournal = {Aquatic Toxicology (Amsterdam, Netherlands)},\n\tauthor = {Hellström, Gustav and Klaminder, Jonatan and Jonsson, Micael and Fick, Jerker and Brodin, Tomas},\n\tmonth = jan,\n\tyear = {2016},\n\tpmid = {26683267},\n\tnote = {00006 },\n\tkeywords = {\\#nosource, Acoustic telemetry, Animals, Aquatic Organisms, Aquatic ecotoxicology, Behavior, Animal, Biomarker, Biomarkers, Monitoring, Telemetry, Toxicity Tests, Water Pollutants, Chemical, behaviour},\n\tpages = {384--389},\n}\n\n\n\n\n\n Laboratory-based behavioural assays are often used in ecotoxicological studies to assess the environmental risk of aquatic contaminants. While results from such laboratory-based risk assessments may be difficult to extrapolate to natural environments, technological advancements over the past decade now make it possible to perform risk assessments through detailed studies of exposed individuals in natural settings. Acoustic telemetry is a technology to monitor movement and behaviour of aquatic organism in oceans, lakes, and rivers. The technology allows for tracking of multiple individuals simultaneously with very high temporal and spatial resolution, with the option to incorporate sensors to measure various physiological and environmental parameters. Although frequently used in fisheries research, aquatic ecotoxicology has been slow to adopt acoustic telemetry as a tool in field-based studies. This mini-review intends to introduce acoustic telemetry to aquatic ecotoxicologists, focusing on the potential of the technology to bridge the gap between laboratory assays and natural behaviours when making toxicological risk assessments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Pathways to sustainable intensification through crop water management.\n \n \n \n \n\n\n \n MacDonald, G. K.; D’Odorico, P.; and Seekell, D. A.\n\n\n \n\n\n\n Environmental Research Letters, 11(9): 091001. 2016.\n 00005\n\n\n\n
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\n\n\n@article{macdonald_pathways_2016,\n\ttitle = {Pathways to sustainable intensification through crop water management},\n\tvolume = {11},\n\tissn = {1748-9326},\n\turl = {http://stacks.iop.org/1748-9326/11/i=9/a=091001},\n\tdoi = {10.1088/1748-9326/11/9/091001},\n\tabstract = {How much could farm water management interventions increase global crop production? This is the central question posed in a global modelling study by Jägermeyr et al (2016 Environ. Res. Lett. 11 [http://dx.doi.org/10.1088/1748-9326/11/2/025002] 025002 ). They define the biophysical realm of possibility for future gains in crop production related to agricultural water practices—enhancing water availability to crops and expanding irrigation by reducing non-productive water consumption. The findings of Jägermeyr et al offer crucial insight on the potential for crop water management to sustainably intensify agriculture, but they also provide a benchmark to consider the broader role of sustainable intensification targets in the global food system. Here, we reflect on how the global crop water management simulations of Jägermeyr et al could interact with: (1) farm size at more local scales, (2) downstream water users at the river basin scale, as well as (3) food trade and (4) demand-side food system strategies at the global scale. Incorporating such cross-scale linkages in future research could highlight the diverse pathways needed to harness the potential of farm-level crop water management for a more productive and sustainable global food system.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2016-09-12},\n\tjournal = {Environmental Research Letters},\n\tauthor = {MacDonald, Graham K. and D’Odorico, Paolo and Seekell, David A.},\n\tyear = {2016},\n\tnote = {00005},\n\tkeywords = {\\#nosource},\n\tpages = {091001},\n}\n\n\n\n\n\n How much could farm water management interventions increase global crop production? This is the central question posed in a global modelling study by Jägermeyr et al (2016 Environ. Res. Lett. 11 [http://dx.doi.org/10.1088/1748-9326/11/2/025002] 025002 ). They define the biophysical realm of possibility for future gains in crop production related to agricultural water practices—enhancing water availability to crops and expanding irrigation by reducing non-productive water consumption. The findings of Jägermeyr et al offer crucial insight on the potential for crop water management to sustainably intensify agriculture, but they also provide a benchmark to consider the broader role of sustainable intensification targets in the global food system. Here, we reflect on how the global crop water management simulations of Jägermeyr et al could interact with: (1) farm size at more local scales, (2) downstream water users at the river basin scale, as well as (3) food trade and (4) demand-side food system strategies at the global scale. Incorporating such cross-scale linkages in future research could highlight the diverse pathways needed to harness the potential of farm-level crop water management for a more productive and sustainable global food system.\n
\n\n\n\n \n\n \n \n \n \n \n \n Modeling the downward transport of 210Pb in Peatlands: Initial Penetration‐Constant Rate of Supply (IP-CRS) model.\n \n \n \n \n\n\n \n Olid, C.; Diego, D.; Garcia-Orellana, J.; Cortizas, A. M.; and Klaminder, J.\n\n\n \n\n\n\n Science of The Total Environment, 541: 1222–1231. January 2016.\n 00005\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{olid_modeling_2016,\n\ttitle = {Modeling the downward transport of {210Pb} in {Peatlands}: {Initial} {Penetration}‐{Constant} {Rate} of {Supply} ({IP}-{CRS}) model},\n\tvolume = {541},\n\tissn = {0048-9697},\n\tshorttitle = {Modeling the downward transport of {210Pb} in {Peatlands}},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0048969715307920},\n\tdoi = {10.1016/j.scitotenv.2015.09.131},\n\tabstract = {The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100–150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used 210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.},\n\turldate = {2017-04-28},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Olid, Carolina and Diego, David and Garcia-Orellana, Jordi and Cortizas, Antonio Martínez and Klaminder, Jonatan},\n\tmonth = jan,\n\tyear = {2016},\n\tnote = {00005},\n\tkeywords = {\\#nosource, 137Cs, 210Pb, 241Am, Americium, Caesium, Chronology, Lead},\n\tpages = {1222--1231},\n}\n\n\n\n\n\n The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100–150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used 210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-term declines in stream and river inorganic nitrogen (N) export correspond to forest change.\n \n \n \n \n\n\n \n Lucas, R. W.; Sponseller, R. A.; Gundale, M. J.; Stendahl, J.; Fridman, J.; Högberg, P.; and Laudon, H.\n\n\n \n\n\n\n Ecological Applications, 26(2): 545–556. March 2016.\n 00011\n\n\n\n
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\n\n\n@article{lucas_long-term_2016,\n\ttitle = {Long-term declines in stream and river inorganic nitrogen ({N}) export correspond to forest change},\n\tvolume = {26},\n\tissn = {1939-5582},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/14-2413/abstract},\n\tdoi = {10.1890/14-2413},\n\tabstract = {Human activities have exerted a powerful influence on the biogeochemical cycles of nitrogen (N) and carbon (C) and drive changes that can be a challenge to predict given the influence of multiple environmental stressors. This study focused on understanding how land management and climate change have together influenced terrestrial N storage and watershed inorganic N export across boreal and sub-arctic landscapes in northern Sweden. Using long-term discharge and nutrient concentration data that have been collected continuously for over three decades, we calculated the hydrologic inorganic N export from nine watersheds in this region. We found a consistent decline in inorganic N export from 1985 to 2011 over the entire region from both small and large watersheds, despite the absence of any long-term trend in river discharge during this period. The steepest declines in inorganic N export were observed during the growing season, consistent with the hypothesis that observed changes are biologically mediated and are not the result of changes in long-term hydrology. Concurrent with the decrease in inorganic N export, we report sustained increases in terrestrial N accumulation in forest biomass and soils across northern Sweden. Given the close communication of nutrient and energy stores between plants, soils, and waters, our results indicate a regional tightening of the N cycle in an already N-limited environment as a result of changes in forest management and climate-mediated growth increases. Our results are consistent with declining inorganic N efflux previously reported from small headwater streams in other ecosystems and shed new light on the mechanisms controlling these patterns by identifying corresponding shifts in the terrestrial N balance, which have been altered by a combination of management activities and climate change.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-01},\n\tjournal = {Ecological Applications},\n\tauthor = {Lucas, Richard W. and Sponseller, Ryan A. and Gundale, Michael J. and Stendahl, Johan and Fridman, Jonas and Högberg, Peter and Laudon, Hjalmar},\n\tmonth = mar,\n\tyear = {2016},\n\tnote = {00011},\n\tkeywords = {\\#nosource, Boreal forest, Sweden, climate-mediated growth increases, forest management, soil N storage, terrestrial N retention, terrestrial biogeochemistry},\n\tpages = {545--556},\n}\n\n\n\n\n\n Human activities have exerted a powerful influence on the biogeochemical cycles of nitrogen (N) and carbon (C) and drive changes that can be a challenge to predict given the influence of multiple environmental stressors. This study focused on understanding how land management and climate change have together influenced terrestrial N storage and watershed inorganic N export across boreal and sub-arctic landscapes in northern Sweden. Using long-term discharge and nutrient concentration data that have been collected continuously for over three decades, we calculated the hydrologic inorganic N export from nine watersheds in this region. We found a consistent decline in inorganic N export from 1985 to 2011 over the entire region from both small and large watersheds, despite the absence of any long-term trend in river discharge during this period. The steepest declines in inorganic N export were observed during the growing season, consistent with the hypothesis that observed changes are biologically mediated and are not the result of changes in long-term hydrology. Concurrent with the decrease in inorganic N export, we report sustained increases in terrestrial N accumulation in forest biomass and soils across northern Sweden. Given the close communication of nutrient and energy stores between plants, soils, and waters, our results indicate a regional tightening of the N cycle in an already N-limited environment as a result of changes in forest management and climate-mediated growth increases. Our results are consistent with declining inorganic N efflux previously reported from small headwater streams in other ecosystems and shed new light on the mechanisms controlling these patterns by identifying corresponding shifts in the terrestrial N balance, which have been altered by a combination of management activities and climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Understory plant functional groups and litter species identity are stronger drivers of litter decomposition than warming along a boreal forest post-fire successional gradient.\n \n \n \n \n\n\n \n De Long, J. R.; Dorrepaal, E.; Kardol, P.; Nilsson, M.; Teuber, L. M.; and Wardle, D. A.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 98: 159–170. July 2016.\n \n\n\n\n
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\n\n\n@article{de_long_understory_2016,\n\ttitle = {Understory plant functional groups and litter species identity are stronger drivers of litter decomposition than warming along a boreal forest post-fire successional gradient},\n\tvolume = {98},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071716300360},\n\tdoi = {10.1016/j.soilbio.2016.04.009},\n\tabstract = {Increasing surface temperatures due to climate change have the potential to alter plant litter mass loss and nutrient release during decomposition. However, a great deal of uncertainty remains concerning how ecosystem functioning may be affected by interactions between warming and other drivers, such as plant functional group composition and environmental context. In this study, we investigated how vascular plant litter decomposition and nutrient release were affected by experimental warming, moss removal and shrub removal along a post-fire boreal forest successional gradient. Our results show that litter decomposition and nutrient loss were primarily driven by understory plant functional group removal. The removal of mosses generally reduced litter mass loss and increased litter phosphorus (P) loss, while shrub removal typically increased litter mass loss and in one litter species reduced immobilization of P. Litter nitrogen (N) loss was unaffected by plant functional group removal. Warming interacted with successional stage and species identity of the litter decomposed, but these effects were uncommon and generally weak. As climate change advances, moss cover is expected to decrease, while shrub cover is expected to increase. Taken together with our results, this suggests that lower moss cover will decrease leaf litter decomposition rates and increase P release from litter, while increasing shrub cover will decrease decomposition rates and may reduce P release from litter. Our results demonstrate that in the short term, the direct effects of warming and successional stage will play a relatively minor role in driving litter decomposition processes in the boreal forest. In the long term, as the climate warms, temperature and its indirect effects via changes in the understory vegetation will play an important role in driving litter decomposition, thereby potentially altering C storage and nutrient cycling.},\n\turldate = {2017-02-07},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {De Long, Jonathan R. and Dorrepaal, Ellen and Kardol, Paul and Nilsson, Marie-Charlotte and Teuber, Laurenz M. and Wardle, David A.},\n\tmonth = jul,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Boreal forest post-fire succession, Carbon storage, Global climate change, Litter decomposition, Plant functional group removal, Plant–soil interactions},\n\tpages = {159--170},\n}\n\n\n\n\n\n Increasing surface temperatures due to climate change have the potential to alter plant litter mass loss and nutrient release during decomposition. However, a great deal of uncertainty remains concerning how ecosystem functioning may be affected by interactions between warming and other drivers, such as plant functional group composition and environmental context. In this study, we investigated how vascular plant litter decomposition and nutrient release were affected by experimental warming, moss removal and shrub removal along a post-fire boreal forest successional gradient. Our results show that litter decomposition and nutrient loss were primarily driven by understory plant functional group removal. The removal of mosses generally reduced litter mass loss and increased litter phosphorus (P) loss, while shrub removal typically increased litter mass loss and in one litter species reduced immobilization of P. Litter nitrogen (N) loss was unaffected by plant functional group removal. Warming interacted with successional stage and species identity of the litter decomposed, but these effects were uncommon and generally weak. As climate change advances, moss cover is expected to decrease, while shrub cover is expected to increase. Taken together with our results, this suggests that lower moss cover will decrease leaf litter decomposition rates and increase P release from litter, while increasing shrub cover will decrease decomposition rates and may reduce P release from litter. Our results demonstrate that in the short term, the direct effects of warming and successional stage will play a relatively minor role in driving litter decomposition processes in the boreal forest. In the long term, as the climate warms, temperature and its indirect effects via changes in the understory vegetation will play an important role in driving litter decomposition, thereby potentially altering C storage and nutrient cycling.\n
\n\n\n\n \n\n \n \n \n \n \n \n Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome.\n \n \n \n \n\n\n \n Virtanen, R.; Oksanen, L.; Oksanen, T.; Cohen, J.; Forbes, B. C.; Johansen, B.; Käyhkö, J.; Olofsson, J.; Pulliainen, J.; and Tømmervik, H.\n\n\n \n\n\n\n Ecology and Evolution, 6(1): 143–158. January 2016.\n \n\n\n\n
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\n\n\n@article{virtanen_where_2016,\n\ttitle = {Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome},\n\tvolume = {6},\n\tissn = {2045-7758},\n\tshorttitle = {Where do the treeless tundra areas of northern highlands fit in the global biome system},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/ece3.1837/abstract},\n\tdoi = {10.1002/ece3.1837},\n\tabstract = {According to some treatises, arctic and alpine sub-biomes are ecologically similar, whereas others find them highly dissimilar. Most peculiarly, large areas of northern tundra highlands fall outside of the two recent subdivisions of the tundra biome. We seek an ecologically natural resolution to this long-standing and far-reaching problem. We studied broad-scale patterns in climate and vegetation along the gradient from Siberian tundra via northernmost Fennoscandia to the alpine habitats of European middle-latitude mountains, as well as explored those patterns within Fennoscandian tundra based on climate–vegetation patterns obtained from a fine-scale vegetation map. Our analyses reveal that ecologically meaningful January–February snow and thermal conditions differ between different types of tundra. High precipitation and mild winter temperatures prevail on middle-latitude mountains, low precipitation and usually cold winters prevail on high-latitude tundra, and Scandinavian mountains show intermediate conditions. Similarly, heath-like plant communities differ clearly between middle latitude mountains (alpine) and high-latitude tundra vegetation, including its altitudinal extension on Scandinavian mountains. Conversely, high abundance of snowbeds and large differences in the composition of dwarf shrub heaths distinguish the Scandinavian mountain tundra from its counterparts in Russia and the north Fennoscandian inland. The European tundra areas fall into three ecologically rather homogeneous categories: the arctic tundra, the oroarctic tundra of northern heights and mountains, and the genuinely alpine tundra of middle-latitude mountains. Attempts to divide the tundra into two sub-biomes have resulted in major discrepancies and confusions, as the oroarctic areas are included in the arctic tundra in some biogeographic maps and in the alpine tundra in others. Our analyses based on climate and vegetation criteria thus seem to resolve the long-standing biome delimitation problem, help in consistent characterization of research sites, and create a basis for further biogeographic and ecological research in global tundra environments.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Virtanen, Risto and Oksanen, Lauri and Oksanen, Tarja and Cohen, Juval and Forbes, Bruce C. and Johansen, Bernt and Käyhkö, Jukka and Olofsson, Johan and Pulliainen, Jouni and Tømmervik, Hans},\n\tmonth = jan,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Arctic, alpine, biome delimitation, ecoregion, mountains, tundra ecosystems, vegetation pattern, winter climate},\n\tpages = {143--158},\n}\n\n\n\n\n\n According to some treatises, arctic and alpine sub-biomes are ecologically similar, whereas others find them highly dissimilar. Most peculiarly, large areas of northern tundra highlands fall outside of the two recent subdivisions of the tundra biome. We seek an ecologically natural resolution to this long-standing and far-reaching problem. We studied broad-scale patterns in climate and vegetation along the gradient from Siberian tundra via northernmost Fennoscandia to the alpine habitats of European middle-latitude mountains, as well as explored those patterns within Fennoscandian tundra based on climate–vegetation patterns obtained from a fine-scale vegetation map. Our analyses reveal that ecologically meaningful January–February snow and thermal conditions differ between different types of tundra. High precipitation and mild winter temperatures prevail on middle-latitude mountains, low precipitation and usually cold winters prevail on high-latitude tundra, and Scandinavian mountains show intermediate conditions. Similarly, heath-like plant communities differ clearly between middle latitude mountains (alpine) and high-latitude tundra vegetation, including its altitudinal extension on Scandinavian mountains. Conversely, high abundance of snowbeds and large differences in the composition of dwarf shrub heaths distinguish the Scandinavian mountain tundra from its counterparts in Russia and the north Fennoscandian inland. The European tundra areas fall into three ecologically rather homogeneous categories: the arctic tundra, the oroarctic tundra of northern heights and mountains, and the genuinely alpine tundra of middle-latitude mountains. Attempts to divide the tundra into two sub-biomes have resulted in major discrepancies and confusions, as the oroarctic areas are included in the arctic tundra in some biogeographic maps and in the alpine tundra in others. Our analyses based on climate and vegetation criteria thus seem to resolve the long-standing biome delimitation problem, help in consistent characterization of research sites, and create a basis for further biogeographic and ecological research in global tundra environments.\n
\n\n\n\n \n\n \n \n \n \n \n \n New Multicentury Evidence for Dispersal Limitation during Primary Succession.\n \n \n \n \n\n\n \n Makoto, K.; and Wilson, S. D.\n\n\n \n\n\n\n The American Naturalist, 187(6): 804–811. March 2016.\n \n\n\n\n
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\n\n\n@article{makoto_new_2016,\n\ttitle = {New {Multicentury} {Evidence} for {Dispersal} {Limitation} during {Primary} {Succession}},\n\tvolume = {187},\n\tissn = {0003-0147},\n\turl = {http://www.journals.uchicago.edu/doi/abs/10.1086/686199},\n\tdoi = {10.1086/686199},\n\tabstract = {Primary succession is limited by both ecosystem development and plant dispersal, but the extent to which dispersal constrains succession over the long-term is unknown. We compared primary succession along two co-occurring arctic chronosequences with contrasting spatial scales: sorted circles that span a few meters and may have few dispersal constraints and glacial forelands that span several kilometers and may have greater dispersal constraints. Dispersal constraints slowed primary succession by centuries: plots were dominated by cryptogams after 20 years on circles but after 270 years on forelands; plots supported deciduous plants after 100 years on circles but after {\\textgreater}400 years on forelands. Our study provides century-scale evidence suggesting that dispersal limitations constrain the rate of primary succession in glacial forelands.},\n\tnumber = {6},\n\turldate = {2017-02-07},\n\tjournal = {The American Naturalist},\n\tauthor = {Makoto, K. and Wilson, Scott D.},\n\tmonth = mar,\n\tyear = {2016},\n\tkeywords = {\\#nosource, arctic, biomass, ecosystem development, foreland, glacier, growth form, soil C, sorted circle},\n\tpages = {804--811},\n}\n\n\n\n\n\n Primary succession is limited by both ecosystem development and plant dispersal, but the extent to which dispersal constrains succession over the long-term is unknown. We compared primary succession along two co-occurring arctic chronosequences with contrasting spatial scales: sorted circles that span a few meters and may have few dispersal constraints and glacial forelands that span several kilometers and may have greater dispersal constraints. Dispersal constraints slowed primary succession by centuries: plots were dominated by cryptogams after 20 years on circles but after 270 years on forelands; plots supported deciduous plants after 100 years on circles but after \\textgreater400 years on forelands. Our study provides century-scale evidence suggesting that dispersal limitations constrain the rate of primary succession in glacial forelands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Short-term climate change manipulation effects do not scale up to long-term legacies : effects of an absent snow cover on boreal forest plants.\n \n \n \n \n\n\n \n Blume-Werry, G.; Kreyling, J.; Laudon, H.; and Milbau, A.\n\n\n \n\n\n\n Journal of Ecology, 104(6): 1638–1648. 2016.\n \n\n\n\n
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\n\n\n@article{blume-werry_short-term_2016,\n\ttitle = {Short-term climate change manipulation effects do not scale up to long-term legacies : effects of an absent snow cover on boreal forest plants},\n\tvolume = {104},\n\tshorttitle = {Short-term climate change manipulation effects do not scale up to long-term legacies},\n\turl = {http://umu.diva-portal.org/smash/record.jsf?pid=diva2:954751},\n\tdoi = {10.1111/1365-2745.12636},\n\tabstract = {1. Despite time-lags and nonlinearity in ecological processes, the majority of our knowledge about ecosystem responses to long-term changes in climate originates from relatively short-term experime ...},\n\tlanguage = {eng},\n\tnumber = {6},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Ecology},\n\tauthor = {Blume-Werry, Gesche and Kreyling, Juergen and Laudon, Hjalmar and Milbau, Ann},\n\tyear = {2016},\n\tkeywords = {\\#nosource, Norway spruce, Picea abies, Vaccinium, minirhizotron, plant-climate interactions, root phenology, snow removal, soil frost, understory},\n\tpages = {1638--1648},\n}\n\n\n\n\n\n 1. Despite time-lags and nonlinearity in ecological processes, the majority of our knowledge about ecosystem responses to long-term changes in climate originates from relatively short-term experime ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-Term Trends and Role of Climate in the Population Dynamics of Eurasian Reindeer.\n \n \n \n \n\n\n \n Uboni, A.; Horstkotte, T.; Kaarlejärvi, E.; Sévêque, A.; Stammler, F.; Olofsson, J.; Forbes, B. C.; and Moen, J.\n\n\n \n\n\n\n PLOS ONE, 11(6): e0158359. June 2016.\n \n\n\n\n
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\n\n\n@article{uboni_long-term_2016,\n\ttitle = {Long-{Term} {Trends} and {Role} of {Climate} in the {Population} {Dynamics} of {Eurasian} {Reindeer}},\n\tvolume = {11},\n\tissn = {1932-6203},\n\turl = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0158359},\n\tdoi = {10.1371/journal.pone.0158359},\n\tabstract = {Temperature is increasing in Arctic and sub-Arctic regions at a higher rate than anywhere else in the world. The frequency and nature of precipitation events are also predicted to change in the future. These changes in climate are expected, together with increasing human pressures, to have significant impacts on Arctic and sub-Arctic species and ecosystems. Due to the key role that reindeer play in those ecosystems, it is essential to understand how climate will affect the region’s most important species. Our study assesses the role of climate on the dynamics of fourteen Eurasian reindeer (Rangifer tarandus) populations, using for the first time data on reindeer abundance collected over a 70-year period, including both wild and semi-domesticated reindeer, and covering more than half of the species’ total range. We analyzed trends in population dynamics, investigated synchrony among population growth rates, and assessed the effects of climate on population growth rates. Trends in the population dynamics were remarkably heterogeneous. Synchrony was apparent only among some populations and was not correlated with distance among population ranges. Proxies of climate variability mostly failed to explain population growth rates and synchrony. For both wild and semi-domesticated populations, local weather, biotic pressures, loss of habitat and human disturbances appear to have been more important drivers of reindeer population dynamics than climate. In semi-domesticated populations, management strategies may have masked the effects of climate. Conservation efforts should aim to mitigate human disturbances, which could exacerbate the potentially negative effects of climate change on reindeer populations in the future. Special protection and support should be granted to those semi-domesticated populations that suffered the most because of the collapse of the Soviet Union, in order to protect the livelihood of indigenous peoples that depend on the species, and the multi-faceted role that reindeer exert in Arctic ecosystems.},\n\tnumber = {6},\n\turldate = {2017-02-08},\n\tjournal = {PLOS ONE},\n\tauthor = {Uboni, Alessia and Horstkotte, Tim and Kaarlejärvi, Elina and Sévêque, Anthony and Stammler, Florian and Olofsson, Johan and Forbes, Bruce C. and Moen, Jon},\n\tmonth = jun,\n\tyear = {2016},\n\tkeywords = {\\#nosource, Norway, Population dynamics, Population growth, Russia, climate change, reindeer, siberia, winter},\n\tpages = {e0158359},\n}\n\n\n\n\n\n Temperature is increasing in Arctic and sub-Arctic regions at a higher rate than anywhere else in the world. The frequency and nature of precipitation events are also predicted to change in the future. These changes in climate are expected, together with increasing human pressures, to have significant impacts on Arctic and sub-Arctic species and ecosystems. Due to the key role that reindeer play in those ecosystems, it is essential to understand how climate will affect the region’s most important species. Our study assesses the role of climate on the dynamics of fourteen Eurasian reindeer (Rangifer tarandus) populations, using for the first time data on reindeer abundance collected over a 70-year period, including both wild and semi-domesticated reindeer, and covering more than half of the species’ total range. We analyzed trends in population dynamics, investigated synchrony among population growth rates, and assessed the effects of climate on population growth rates. Trends in the population dynamics were remarkably heterogeneous. Synchrony was apparent only among some populations and was not correlated with distance among population ranges. Proxies of climate variability mostly failed to explain population growth rates and synchrony. For both wild and semi-domesticated populations, local weather, biotic pressures, loss of habitat and human disturbances appear to have been more important drivers of reindeer population dynamics than climate. In semi-domesticated populations, management strategies may have masked the effects of climate. Conservation efforts should aim to mitigate human disturbances, which could exacerbate the potentially negative effects of climate change on reindeer populations in the future. Special protection and support should be granted to those semi-domesticated populations that suffered the most because of the collapse of the Soviet Union, in order to protect the livelihood of indigenous peoples that depend on the species, and the multi-faceted role that reindeer exert in Arctic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation.\n \n \n \n \n\n\n \n Pauchard, A.; Milbau, A.; Albihn, A.; Alexander, J.; Burgess, T.; Daehler, C.; Englund, G.; Essl, F.; Evengård, B.; Greenwood, G. B.; Haider, S.; Lenoir, J.; McDougall, K.; Muths, E.; Nuñez, M. A.; Olofsson, J.; Pellissier, L.; Rabitsch, W.; Rew, L. J.; Robertson, M.; Sanders, N.; and Kueffer, C.\n\n\n \n\n\n\n Biological Invasions, 18(2): 345–353. February 2016.\n \n\n\n\n
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\n\n\n@article{pauchard_non-native_2016,\n\ttitle = {Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation},\n\tvolume = {18},\n\tissn = {1387-3547, 1573-1464},\n\tshorttitle = {Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change},\n\turl = {http://link.springer.com/10.1007/s10530-015-1025-x},\n\tdoi = {10.1007/s10530-015-1025-x},\n\tabstract = {00003},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2016-10-18},\n\tjournal = {Biological Invasions},\n\tauthor = {Pauchard, Aníbal and Milbau, Ann and Albihn, Ann and Alexander, Jake and Burgess, Treena and Daehler, Curtis and Englund, Göran and Essl, Franz and Evengård, Birgitta and Greenwood, Gregory B. and Haider, Sylvia and Lenoir, Jonathan and McDougall, Keith and Muths, Erin and Nuñez, Martin A. and Olofsson, Johan and Pellissier, Loic and Rabitsch, Wolfgang and Rew, Lisa J. and Robertson, Mark and Sanders, Nathan and Kueffer, Christoph},\n\tmonth = feb,\n\tyear = {2016},\n\tkeywords = {\\#nosource},\n\tpages = {345--353},\n}\n\n\n\n\n\n 00003\n
\n\n\n\n \n\n \n \n \n \n \n Nematode community resistant to deep soil frost in boreal forest soils.\n \n \n \n\n\n \n De Long, J. R.; Laudon, H.; Blume-Werry, G.; and Kardol, P.\n\n\n \n\n\n\n Pedobiologia, 59(5-6): 243–251. 2016.\n \n\n\n\n
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\n\n\n@article{de_long_nematode_2016,\n\ttitle = {Nematode community resistant to deep soil frost in boreal forest soils},\n\tvolume = {59},\n\tissn = {0031-4056},\n\tdoi = {10.1016/j.pedobi.2016.10.001},\n\tabstract = {As global climate change advances, shifts in winter precipitation are becoming more common in high latitude ecosystems, resulting in less insulating snow cover and deeper soil frost. Long-term alterations to soil frost can impact on ecosystem processes such as decomposition, microbial activity and vegetation dynamics. In this study we utilized the longest running, well-characterized soil frost manipulation experiment in a boreal forest. We measured nematode family composition and feeding group abundances at four different soil layer depths from plots that had been subjected to deep soil frost for one and 11 years. The overall abundance of nematodes and the different feeding groups were unaffected by deep soil frost. However, a higher Maturity Index was weakly associated with deep soil frost (indicative of lower nutrient enrichment and more persister nematode (i.e., K-strategist) families), likely due to the loss of nutrients and reduced inputs from inhibited decomposition. Multivariate and regression analyses showed that most nematode families were weakly associated with dominant understory plant species and strongly associated with soil organic matter (SOM). This is probably the result of higher resource availability in the control plots, which is favorable to the nematode community. These results indicate that the nematode community was more strongly driven by the long-term indirect effects of deep soil frost on SOM as opposed to the direct effects. Our findings highlight that the indirect effects of altered winter precipitation and soil frost patterns may be more important than direct winter climate effects. Further, such indirect effects on SOM and the plant community that may affect the nematode community can only be seen in long-term experiments. Finally, given the critical role nematodes play in soil food webs and carbon and nutrient cycling, our results demonstrate the necessity of considering the response of nematodes to global climate change in boreal forest soils. (C) 2016 Elsevier GmbH. All rights reserved.},\n\tlanguage = {English},\n\tnumber = {5-6},\n\tjournal = {Pedobiologia},\n\tauthor = {De Long, Jonathan R. and Laudon, Hjalmar and Blume-Werry, Gesche and Kardol, Paul},\n\tyear = {2016},\n\tkeywords = {\\#nosource, Boreal forest, CO2, Enrichment, Global climate change, Mineralization, Nematodes, Riparian zone, Soil frost, climate, food-web, grassland ecosystems, hardwood forest, manipulation, respiration, snow removal},\n\tpages = {243--251},\n}\n\n\n\n\n\n As global climate change advances, shifts in winter precipitation are becoming more common in high latitude ecosystems, resulting in less insulating snow cover and deeper soil frost. Long-term alterations to soil frost can impact on ecosystem processes such as decomposition, microbial activity and vegetation dynamics. In this study we utilized the longest running, well-characterized soil frost manipulation experiment in a boreal forest. We measured nematode family composition and feeding group abundances at four different soil layer depths from plots that had been subjected to deep soil frost for one and 11 years. The overall abundance of nematodes and the different feeding groups were unaffected by deep soil frost. However, a higher Maturity Index was weakly associated with deep soil frost (indicative of lower nutrient enrichment and more persister nematode (i.e., K-strategist) families), likely due to the loss of nutrients and reduced inputs from inhibited decomposition. Multivariate and regression analyses showed that most nematode families were weakly associated with dominant understory plant species and strongly associated with soil organic matter (SOM). This is probably the result of higher resource availability in the control plots, which is favorable to the nematode community. These results indicate that the nematode community was more strongly driven by the long-term indirect effects of deep soil frost on SOM as opposed to the direct effects. Our findings highlight that the indirect effects of altered winter precipitation and soil frost patterns may be more important than direct winter climate effects. Further, such indirect effects on SOM and the plant community that may affect the nematode community can only be seen in long-term experiments. Finally, given the critical role nematodes play in soil food webs and carbon and nutrient cycling, our results demonstrate the necessity of considering the response of nematodes to global climate change in boreal forest soils. (C) 2016 Elsevier GmbH. All rights reserved.\n
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\n \n \n\n \n \n \n \n \n \n Ecosystem Consequences of Changing Inputs of Terrestrial Dissolved Organic Matter to Lakes: Current Knowledge and Future Challenges.\n \n \n \n \n\n\n \n Solomon, C. T.; Jones, S. E.; Weidel, B. C.; Buffam, I.; Fork, M. L.; Karlsson, J.; Larsen, S.; Lennon, J. T.; Read, J. S.; Sadro, S.; and Saros, J. E.\n\n\n \n\n\n\n Ecosystems, 18(3): 376–389. April 2015.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{solomon_ecosystem_2015,\n\ttitle = {Ecosystem {Consequences} of {Changing} {Inputs} of {Terrestrial} {Dissolved} {Organic} {Matter} to {Lakes}: {Current} {Knowledge} and {Future} {Challenges}},\n\tvolume = {18},\n\tissn = {1435-0629},\n\tshorttitle = {Ecosystem {Consequences} of {Changing} {Inputs} of {Terrestrial} {Dissolved} {Organic} {Matter} to {Lakes}},\n\turl = {https://doi.org/10.1007/s10021-015-9848-y},\n\tdoi = {10.1007/s10021-015-9848-y},\n\tabstract = {Lake ecosystems and the services that they provide to people are profoundly influenced by dissolved organic matter derived from terrestrial plant tissues. These terrestrial dissolved organic matter (tDOM) inputs to lakes have changed substantially in recent decades, and will likely continue to change. In this paper, we first briefly review the substantial literature describing tDOM effects on lakes and ongoing changes in tDOM inputs. We then identify and provide examples of four major challenges which limit predictions about the implications of tDOM change for lakes, as follows: First, it is currently difficult to forecast future tDOM inputs for particular lakes or lake regions. Second, tDOM influences ecosystems via complex, interacting, physical-chemical-biological effects and our holistic understanding of those effects is still rudimentary. Third, non-linearities and thresholds in relationships between tDOM inputs and ecosystem processes have not been well described. Fourth, much understanding of tDOM effects is built on comparative studies across space that may not capture likely responses through time. We conclude by identifying research approaches that may be important for overcoming those challenges in order to provide policy- and management-relevant predictions about the implications of changing tDOM inputs for lakes.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Solomon, Christopher T. and Jones, Stuart E. and Weidel, Brian C. and Buffam, Ishi and Fork, Megan L. and Karlsson, Jan and Larsen, Søren and Lennon, Jay T. and Read, Jordan S. and Sadro, Steven and Saros, Jasmine E.},\n\tmonth = apr,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Environmental Management, Geoecology/Natural Processes, Hydrology/Water Resources, Plant Sciences, Zoology, allochthonous, dissolved organic carbon, dissolved organic matter, ecology, ecosystem, environmental change, lake, review, terrestrial inputs},\n\tpages = {376--389},\n}\n\n\n\n\n\n Lake ecosystems and the services that they provide to people are profoundly influenced by dissolved organic matter derived from terrestrial plant tissues. These terrestrial dissolved organic matter (tDOM) inputs to lakes have changed substantially in recent decades, and will likely continue to change. In this paper, we first briefly review the substantial literature describing tDOM effects on lakes and ongoing changes in tDOM inputs. We then identify and provide examples of four major challenges which limit predictions about the implications of tDOM change for lakes, as follows: First, it is currently difficult to forecast future tDOM inputs for particular lakes or lake regions. Second, tDOM influences ecosystems via complex, interacting, physical-chemical-biological effects and our holistic understanding of those effects is still rudimentary. Third, non-linearities and thresholds in relationships between tDOM inputs and ecosystem processes have not been well described. Fourth, much understanding of tDOM effects is built on comparative studies across space that may not capture likely responses through time. We conclude by identifying research approaches that may be important for overcoming those challenges in order to provide policy- and management-relevant predictions about the implications of changing tDOM inputs for lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Trade-off between competition and facilitation defines gap colonization in mountains.\n \n \n \n \n\n\n \n Lembrechts, J. J.; Milbau, A.; and Nijs, I.\n\n\n \n\n\n\n AoB PLANTS, 7: plv128. January 2015.\n \n\n\n\n
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\n\n\n@article{lembrechts_trade-off_2015,\n\ttitle = {Trade-off between competition and facilitation defines gap colonization in mountains},\n\tvolume = {7},\n\tissn = {2041-2851},\n\turl = {https://doi.org/10.1093/aobpla/plv128},\n\tdoi = {10.1093/aobpla/plv128},\n\tabstract = {Recent experimental observations show that gap colonization in small-stature (e.g. grassland and dwarf shrubs) vegetation strongly depends on the abiotic conditions within them. At the same time, within-gap variation in biotic interactions such as competition and facilitation, caused by distance to the gap edge, would affect colonizer performance, but a theoretical framework to explore such patterns is missing. Here, we model how competition, facilitation and environmental conditions together determine the small-scale patterns of gap colonization along a cold gradient in mountains, by simulating colonizer survival in gaps of various sizes. Our model adds another dimension to the known effects of biotic interactions along a stress gradient by focussing on the trade-off between competition and facilitation in the within-gap environment. We show that this trade-off defines a peak in colonizer survival at a specific distance from the gap edge, which progressively shifts closer to the edge as the environment gets colder, ultimately leaving a large fraction of gaps unsuitable for colonization in facilitation-dominated systems. This is reinforced when vegetation size and temperature amelioration are manipulated simultaneously with temperature in order to simulate an elevational gradient more realistically. Interestingly, all other conditions being equal, the magnitude of the realized survival peak was always lower in large than in small gaps, making large gaps harder to colonize. The model is relevant to predict effects of non-native plant invasions and climate warming on colonization processes in mountains.},\n\turldate = {2024-03-27},\n\tjournal = {AoB PLANTS},\n\tauthor = {Lembrechts, Jonas J. and Milbau, Ann and Nijs, Ivan},\n\tmonth = jan,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Alien plant invasion, Gradients, cold climates, disturbance, gap invasion, mountains, plant-plant interactions, stress gradient hypothesis},\n\tpages = {plv128},\n}\n\n\n\n\n\n Recent experimental observations show that gap colonization in small-stature (e.g. grassland and dwarf shrubs) vegetation strongly depends on the abiotic conditions within them. At the same time, within-gap variation in biotic interactions such as competition and facilitation, caused by distance to the gap edge, would affect colonizer performance, but a theoretical framework to explore such patterns is missing. Here, we model how competition, facilitation and environmental conditions together determine the small-scale patterns of gap colonization along a cold gradient in mountains, by simulating colonizer survival in gaps of various sizes. Our model adds another dimension to the known effects of biotic interactions along a stress gradient by focussing on the trade-off between competition and facilitation in the within-gap environment. We show that this trade-off defines a peak in colonizer survival at a specific distance from the gap edge, which progressively shifts closer to the edge as the environment gets colder, ultimately leaving a large fraction of gaps unsuitable for colonization in facilitation-dominated systems. This is reinforced when vegetation size and temperature amelioration are manipulated simultaneously with temperature in order to simulate an elevational gradient more realistically. Interestingly, all other conditions being equal, the magnitude of the realized survival peak was always lower in large than in small gaps, making large gaps harder to colonize. The model is relevant to predict effects of non-native plant invasions and climate warming on colonization processes in mountains.\n
\n\n\n\n \n\n \n \n \n \n \n \n Thermal Stability of Goethite-Bound Natural Organic Matter Is Impacted by Carbon Loading.\n \n \n \n \n\n\n \n Feng, W.; Klaminder, J.; and Boily, J.\n\n\n \n\n\n\n The Journal of Physical Chemistry A, 119(51): 12790–12796. December 2015.\n Publisher: American Chemical Society\n\n\n\n
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\n\n\n@article{feng_thermal_2015,\n\ttitle = {Thermal {Stability} of {Goethite}-{Bound} {Natural} {Organic} {Matter} {Is} {Impacted} by {Carbon} {Loading}},\n\tvolume = {119},\n\tissn = {1089-5639},\n\turl = {https://doi.org/10.1021/acs.jpca.5b09821},\n\tdoi = {10.1021/acs.jpca.5b09821},\n\tabstract = {Dissolved natural organic matter (NOM) sorption at mineral surfaces can significantly affect the persistence of organic carbon in soils and sediments. Consequently, determining the mechanisms that stabilize sorbed NOM is crucial for predicting the persistence of carbon in nature. This study determined the effects of loadings and pH on the thermal stability of NOM associated with synthetic goethite (α-FeOOH) particle surfaces, as a proxy for NOM–mineral interactions taking place in nature. NOM thermal stability was investigated using temperature-programmed desorption (TPD) in the 30–700 °C range to collect vibration spectra of thermally decomposing goethite–NOM assemblages, and to concomitantly analyze evolved gases using mass spectrometry. Results showed that NOM thermal stability, indicated by the range of temperatures in which CO2 evolved during thermal decomposition, was greatest in unbound NOM and lowest when NOM was bound to goethite. NOM thermal stability was also loading dependent. It decreased when loadings were in increased the 0.01 to 0.42 mg C m−2 range, where the upper value corresponds to a Langmuirian adsorption maximum. Concomitant Fourier transform infrared (FTIR) spectroscopy measurement showed that these lowered stabilities could be ascribed to direct NOM-goethite interactions that dominated the NOM binding environment. Mineral surface interactions at larger loadings involved, on the contrary, a smaller fraction of the sorbed NOM, thus increasing thermal stability toward that of its unbound counterpart. This study thus identifies a sorption threshold below which NOM sorption to goethite decreases NOM thermal stability, and above which no strong effects are manifested. This should likely influence the fate of organic carbon exposed to thermal gradients in natural environments.},\n\tnumber = {51},\n\turldate = {2024-03-26},\n\tjournal = {The Journal of Physical Chemistry A},\n\tauthor = {Feng, Wenting and Klaminder, Jonatan and Boily, Jean-François},\n\tmonth = dec,\n\tyear = {2015},\n\tnote = {Publisher: American Chemical Society},\n\tkeywords = {\\#nosource},\n\tpages = {12790--12796},\n}\n\n\n\n\n\n Dissolved natural organic matter (NOM) sorption at mineral surfaces can significantly affect the persistence of organic carbon in soils and sediments. Consequently, determining the mechanisms that stabilize sorbed NOM is crucial for predicting the persistence of carbon in nature. This study determined the effects of loadings and pH on the thermal stability of NOM associated with synthetic goethite (α-FeOOH) particle surfaces, as a proxy for NOM–mineral interactions taking place in nature. NOM thermal stability was investigated using temperature-programmed desorption (TPD) in the 30–700 °C range to collect vibration spectra of thermally decomposing goethite–NOM assemblages, and to concomitantly analyze evolved gases using mass spectrometry. Results showed that NOM thermal stability, indicated by the range of temperatures in which CO2 evolved during thermal decomposition, was greatest in unbound NOM and lowest when NOM was bound to goethite. NOM thermal stability was also loading dependent. It decreased when loadings were in increased the 0.01 to 0.42 mg C m−2 range, where the upper value corresponds to a Langmuirian adsorption maximum. Concomitant Fourier transform infrared (FTIR) spectroscopy measurement showed that these lowered stabilities could be ascribed to direct NOM-goethite interactions that dominated the NOM binding environment. Mineral surface interactions at larger loadings involved, on the contrary, a smaller fraction of the sorbed NOM, thus increasing thermal stability toward that of its unbound counterpart. This study thus identifies a sorption threshold below which NOM sorption to goethite decreases NOM thermal stability, and above which no strong effects are manifested. This should likely influence the fate of organic carbon exposed to thermal gradients in natural environments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice cover dynamics.\n \n \n \n \n\n\n \n Denfeld, B. A.; Wallin, M. B.; Sahlée, E.; Sobek, S.; Kokic, J.; Chmiel, H. E.; and Weyhenmeyer, G. A.\n\n\n \n\n\n\n Boreal environment research, 20(6): 679–692. 2015.\n \n\n\n\n
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\n\n\n@article{denfeld_temporal_2015,\n\ttitle = {Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice cover dynamics},\n\tvolume = {20},\n\turl = {http://www.diva-portal.org/smash/record.jsf?pid=diva2:872262},\n\tabstract = {Global carbon dioxide (CO2) emission estimates from inland waters commonly neglect the ice-cover season. To account for CO2 accumulation below ice and consequent emissions into the atmosphere at ic ...},\n\tlanguage = {eng},\n\tnumber = {6},\n\turldate = {2017-05-27},\n\tjournal = {Boreal environment research},\n\tauthor = {Denfeld, Blaize A. and Wallin, Marcus B. and Sahlée, Erik and Sobek, Sebastian and Kokic, Jovana and Chmiel, Hannah E. and Weyhenmeyer, Gesa A.},\n\tyear = {2015},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {679--692},\n}\n\n\n\n\n\n Global carbon dioxide (CO2) emission estimates from inland waters commonly neglect the ice-cover season. To account for CO2 accumulation below ice and consequent emissions into the atmosphere at ic ...\n
\n\n\n\n \n\n \n \n \n \n \n Cryogenic disturbance and its impact on carbon fluxes in a subarctic heathland.\n \n \n \n\n\n \n Becher, M.; Olofsson, J.; and Klaminder, J.\n\n\n \n\n\n\n Environmental Research Letters, 10(11): 114006. November 2015.\n 00002\n\n\n\n
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\n\n\n@article{becher_cryogenic_2015,\n\ttitle = {Cryogenic disturbance and its impact on carbon fluxes in a subarctic heathland},\n\tvolume = {10},\n\tissn = {1748-9326},\n\tdoi = {2020031315140592},\n\tabstract = {Differential frost heave, along with the associated cryogenic disturbance that accompanies it, is an almost universal feature of arctic landscapes that potentially influences the fate of the soil carbon (C) stored in arctic soils. In this study, we quantify how gross ecosystem photosynthesis (GEP), soil respiration (Re) and the resulting net ecosystem exchange (NEE) vary in a patterned ground system (non-sorted circles) at plot-scale and whole-patterned ground scales in response to cryogenic disturbances (differential heave and soil surface disruption). We found that: (i) all studied non-sorted circles (n = 15) acted as net CO2 sources (positive NEE); (ii) GEP showed a weaker decrease than Re in response to increased cryogenic disturbance/decreased humus cover, indicating that undisturbed humus-covered sites are currently the main source of atmospheric CO2 in the studied system. Interestingly, Re fluxes normalized to Cpools indicated that C is currently respired more rapidly at sites exposed to cryogenic disturbances; hence, higher NEE fluxes at less disturbed sites are likely an effect of a more slowly degrading but larger total pool that was built up in the past. Our results highlight the complex effects of cryogenic processes on the Ccycle at various time scales.},\n\tlanguage = {English},\n\tnumber = {11},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Becher, Marina and Olofsson, Johan and Klaminder, Jonatan},\n\tmonth = nov,\n\tyear = {2015},\n\tnote = {00002},\n\tkeywords = {\\#nosource, CO2, Sweden, age, alaska, climate-change, nonsorted circles, organic-carbon, permafrost-affected soils, tundra, vegetation, ⚠️ Invalid DOI},\n\tpages = {114006},\n}\n\n\n\n\n\n Differential frost heave, along with the associated cryogenic disturbance that accompanies it, is an almost universal feature of arctic landscapes that potentially influences the fate of the soil carbon (C) stored in arctic soils. In this study, we quantify how gross ecosystem photosynthesis (GEP), soil respiration (Re) and the resulting net ecosystem exchange (NEE) vary in a patterned ground system (non-sorted circles) at plot-scale and whole-patterned ground scales in response to cryogenic disturbances (differential heave and soil surface disruption). We found that: (i) all studied non-sorted circles (n = 15) acted as net CO2 sources (positive NEE); (ii) GEP showed a weaker decrease than Re in response to increased cryogenic disturbance/decreased humus cover, indicating that undisturbed humus-covered sites are currently the main source of atmospheric CO2 in the studied system. Interestingly, Re fluxes normalized to Cpools indicated that C is currently respired more rapidly at sites exposed to cryogenic disturbances; hence, higher NEE fluxes at less disturbed sites are likely an effect of a more slowly degrading but larger total pool that was built up in the past. Our results highlight the complex effects of cryogenic processes on the Ccycle at various time scales.\n
\n\n\n\n \n\n \n \n \n \n \n \n Personal Norms for Dealing with Climate Change: Results from a Survey Using Moral Foundations Theory.\n \n \n \n \n\n\n \n Jansson, J.; and Dorrepaal, E.\n\n\n \n\n\n\n Sustainable Development, 23(6): 381–395. December 2015.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
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\n\n\n@article{jansson_personal_2015,\n\ttitle = {Personal {Norms} for {Dealing} with {Climate} {Change}: {Results} from a {Survey} {Using} {Moral} {Foundations} {Theory}},\n\tvolume = {23},\n\tissn = {0968-0802},\n\turl = {https://doi.org/10.1002/sd.1598},\n\tdoi = {10.1002/sd.1598},\n\tabstract = {Abstract Climate change has become one of the main issues in environmental and sustainability discussions during the last decade. Acting to reduce climate change can be viewed as a prosocial behavior, and previous research has found that personal norms are important in explaining these types of behaviors, together with other attitudinal factors. In this study we use Moral Foundations Theory (MFT) to explore the antecedents of personal climate change norms together with three attitudinal factors: problem awareness, social norms and adherence to the New Ecological Paradigm. Analyzing data from a nationwide survey (N = 1086) conducted in Sweden, we find that the moral foundations concerning harm and fairness are positively associated with personal climate change norms, whereas authority has a negative relation. However, the moral foundations from MFT contribute less in explaining personal climate change norms compared with the attitudinal factors included in the study. Theoretical and empirical implications are discussed. ? 2015 The Authors Sustainable Development published by ERP Environment and John Wiley \\& Sons Ltd},\n\tnumber = {6},\n\turldate = {2023-07-21},\n\tjournal = {Sustainable Development},\n\tauthor = {Jansson, Johan and Dorrepaal, Ellen},\n\tmonth = dec,\n\tyear = {2015},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource, Moral Foundations Theory (MFT), attitudes, personal norms, questionnaire survey},\n\tpages = {381--395},\n}\n\n\n\n\n\n Abstract Climate change has become one of the main issues in environmental and sustainability discussions during the last decade. Acting to reduce climate change can be viewed as a prosocial behavior, and previous research has found that personal norms are important in explaining these types of behaviors, together with other attitudinal factors. In this study we use Moral Foundations Theory (MFT) to explore the antecedents of personal climate change norms together with three attitudinal factors: problem awareness, social norms and adherence to the New Ecological Paradigm. Analyzing data from a nationwide survey (N = 1086) conducted in Sweden, we find that the moral foundations concerning harm and fairness are positively associated with personal climate change norms, whereas authority has a negative relation. However, the moral foundations from MFT contribute less in explaining personal climate change norms compared with the attitudinal factors included in the study. Theoretical and empirical implications are discussed. ? 2015 The Authors Sustainable Development published by ERP Environment and John Wiley & Sons Ltd\n
\n\n\n\n \n\n \n \n \n \n \n \n Across-Habitat Comparison of Diazotroph Activity in the Subarctic.\n \n \n \n \n\n\n \n Rousk, K.; Sorensen, P. L.; Lett, S.; and Michelsen, A.\n\n\n \n\n\n\n Microbial Ecology, 69(4): 778–787. May 2015.\n 00007\n\n\n\n
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\n\n\n@article{rousk_across-habitat_2015,\n\ttitle = {Across-{Habitat} {Comparison} of {Diazotroph} {Activity} in the {Subarctic}},\n\tvolume = {69},\n\tissn = {0095-3628, 1432-184X},\n\turl = {http://link.springer.com/article/10.1007/s00248-014-0534-y},\n\tdoi = {10.1007/s00248-014-0534-y},\n\tabstract = {Nitrogen (N) fixation by N2-fixing bacteria (diazotrophs) is the primary N input to pristine ecosystems like boreal forests and subarctic and arctic tundra. However, the contribution by the various diazotrophs to habitat N2 fixation remains unclear. We present results from in situ assessments of N2 fixation of five diazotroph associations (with a legume, lichen, feather moss, Sphagnum moss and free-living) incorporating the ground cover of the associations in five typical habitats in the subarctic (wet and dry heath, polygon-heath, birch forest, mire). Further, we assessed the importance of soil and air temperature, as well as moisture conditions for N2 fixation. Across the growing season, the legume had the highest total as well as the highest fraction of N2 fixation rates at habitat level in the heaths ({\\textgreater}85 \\% of habitat N2 fixation), whereas the free-living diazotrophs had the highest N2 fixation rates in the polygon heath (56 \\%), the lichen in the birch forest (87 \\%) and Sphagnum in the mire (100 \\%). The feather moss did not contribute more than 15 \\% to habitat N2 fixation in any of the habitats despite its high ground cover. Moisture content seemed to be a major driver of N2 fixation in the lichen, feather moss and free-living diazotrophs. Our results show that the range of N2 fixers found in pristine habitats contribute differently to habitat N2 fixation and that ground cover of the associates does not necessarily mirror contribution.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-08},\n\tjournal = {Microbial Ecology},\n\tauthor = {Rousk, Kathrin and Sorensen, Pernille L. and Lett, Signe and Michelsen, Anders},\n\tmonth = may,\n\tyear = {2015},\n\tnote = {00007},\n\tkeywords = {\\#nosource, Boreal forest, Cyanobacteria, Geoecology/Natural Processes, Heterotrophs, Methanotrophs, Microbial Ecology, Microbiology, N deposition, Nature Conservation, Nitrogen fixation, Water Quality/Water Pollution, ecology, subarctic tundra, symbiosis},\n\tpages = {778--787},\n}\n\n\n\n\n\n Nitrogen (N) fixation by N2-fixing bacteria (diazotrophs) is the primary N input to pristine ecosystems like boreal forests and subarctic and arctic tundra. However, the contribution by the various diazotrophs to habitat N2 fixation remains unclear. We present results from in situ assessments of N2 fixation of five diazotroph associations (with a legume, lichen, feather moss, Sphagnum moss and free-living) incorporating the ground cover of the associations in five typical habitats in the subarctic (wet and dry heath, polygon-heath, birch forest, mire). Further, we assessed the importance of soil and air temperature, as well as moisture conditions for N2 fixation. Across the growing season, the legume had the highest total as well as the highest fraction of N2 fixation rates at habitat level in the heaths (\\textgreater85 % of habitat N2 fixation), whereas the free-living diazotrophs had the highest N2 fixation rates in the polygon heath (56 %), the lichen in the birch forest (87 %) and Sphagnum in the mire (100 %). The feather moss did not contribute more than 15 % to habitat N2 fixation in any of the habitats despite its high ground cover. Moisture content seemed to be a major driver of N2 fixation in the lichen, feather moss and free-living diazotrophs. Our results show that the range of N2 fixers found in pristine habitats contribute differently to habitat N2 fixation and that ground cover of the associates does not necessarily mirror contribution.\n
\n\n\n\n \n\n \n \n \n \n \n \n Riparian and in-stream restoration of boreal streams and rivers: success or failure?.\n \n \n \n \n\n\n \n Nilsson, C.; Polvi, L. E.; Gardeström, J.; Hasselquist, E. M.; Lind, L.; and Sarneel, J. M.\n\n\n \n\n\n\n Ecohydrology, 8(5): 753–764. 2015.\n \n\n\n\n
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\n\n\n@article{nilsson_riparian_2015,\n\ttitle = {Riparian and in-stream restoration of boreal streams and rivers: success or failure?},\n\tvolume = {8},\n\tcopyright = {Copyright © 2014 John Wiley \\& Sons, Ltd.},\n\tissn = {1936-0592},\n\tshorttitle = {Riparian and in-stream restoration of boreal streams and rivers},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1002/eco.1480},\n\tdoi = {10.1002/eco.1480},\n\tabstract = {We reviewed follow-up studies from Finnish and Swedish streams that have been restored after timber floating to assess the abiotic and biotic responses to restoration. More specifically, from a review of 18 case studies (16 published and 2 unpublished), we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration. Restoration entailed returning coarse sediment (cobbles and boulders) and sometimes large wood to previously channelized turbulent reaches, primarily with the objective of meeting habitat requirements of naturally reproducing salmonid fish. The restored streams showed a consistent increase in channel complexity and retention capacity, but the biotic responses were weak or absent in most species groups. Aquatic mosses growing on boulders were drastically reduced shortly after restoration, but in most studies, they recovered after a few years. Riparian plants, macroinvertebrates and fish did not show any consistent trends in response. We discuss seven alternative explanations to these inconsistent results and conclude that two decades is probably too short a time for most organisms to recover. We recommend long-term monitoring using standardized methods, a landscape-scale perspective and a wider range of organisms to improve the basis for judging to what extent restoration in boreal streams has achieved its goal of reducing the impacts from timber floating. Copyright © 2014 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2019-03-27},\n\tjournal = {Ecohydrology},\n\tauthor = {Nilsson, Christer and Polvi, Lina E. and Gardeström, Johanna and Hasselquist, Eliza Maher and Lind, Lovisa and Sarneel, Judith M.},\n\tyear = {2015},\n\tkeywords = {\\#nosource, recovery, restoration, streams, timber floating},\n\tpages = {753--764},\n}\n\n\n\n\n\n We reviewed follow-up studies from Finnish and Swedish streams that have been restored after timber floating to assess the abiotic and biotic responses to restoration. More specifically, from a review of 18 case studies (16 published and 2 unpublished), we determined whether different taxonomic groups react differently or require different periods of time to respond to the same type of restoration. Restoration entailed returning coarse sediment (cobbles and boulders) and sometimes large wood to previously channelized turbulent reaches, primarily with the objective of meeting habitat requirements of naturally reproducing salmonid fish. The restored streams showed a consistent increase in channel complexity and retention capacity, but the biotic responses were weak or absent in most species groups. Aquatic mosses growing on boulders were drastically reduced shortly after restoration, but in most studies, they recovered after a few years. Riparian plants, macroinvertebrates and fish did not show any consistent trends in response. We discuss seven alternative explanations to these inconsistent results and conclude that two decades is probably too short a time for most organisms to recover. We recommend long-term monitoring using standardized methods, a landscape-scale perspective and a wider range of organisms to improve the basis for judging to what extent restoration in boreal streams has achieved its goal of reducing the impacts from timber floating. Copyright © 2014 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n Above-ground and below-ground plant responses to fertilization in two subarctic ecosystems.\n \n \n \n\n\n \n Veen, G. F.; Sundqvist, M. K.; Metcalfe, D.; and Wilson, S. D.\n\n\n \n\n\n\n Arctic Antarctic and Alpine Research, 47(4): 693–702. November 2015.\n 00002\n\n\n\n
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\n\n\n@article{veen_above-ground_2015,\n\ttitle = {Above-ground and below-ground plant responses to fertilization in two subarctic ecosystems},\n\tvolume = {47},\n\tissn = {1523-0430},\n\tdoi = {10.1657/AAAR0014-085},\n\tabstract = {Soil nutrient supply is likely to change in the Arctic due to altered process rates associated with climate change. Here, we compare the responses of herbaceous tundra and birch forest understory to fertilization, considering both above-and below-ground responses. We added nitrogen and phosphorus to plots in both vegetation types for three years near Abisko, northern Sweden, and measured the effect on above-and below-ground plant community properties and soil characteristics. Fertilization increased ground-layer shoot mass, the cover of grasses, and tended to enhance total root length below-ground, while it reduced the cover of low statured deciduous dwarf-shrubs. The only statistically significant interaction between vegetation type and fertilization was for grass cover, which increased twofold in forest understory but sixfold in tundra following fertilization. The lack of interactions for other variables suggests that the ground layers in these contrasting vegetation types have similar responses to fertilization. The nutrient-driven increase in grass cover and species-specific differences in productivity and root characters may alter ecosystem dynamics and C cycling in the long-term, but our study indicates that the response of birch forest understory and tundra vegetation may be consistent.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Arctic Antarctic and Alpine Research},\n\tauthor = {Veen, G. F. and Sundqvist, Maja K. and Metcalfe, Daniel and Wilson, Scott D.},\n\tmonth = nov,\n\tyear = {2015},\n\tnote = {00002},\n\tkeywords = {\\#nosource, abundance, colonization},\n\tpages = {693--702},\n}\n\n\n\n\n\n Soil nutrient supply is likely to change in the Arctic due to altered process rates associated with climate change. Here, we compare the responses of herbaceous tundra and birch forest understory to fertilization, considering both above-and below-ground responses. We added nitrogen and phosphorus to plots in both vegetation types for three years near Abisko, northern Sweden, and measured the effect on above-and below-ground plant community properties and soil characteristics. Fertilization increased ground-layer shoot mass, the cover of grasses, and tended to enhance total root length below-ground, while it reduced the cover of low statured deciduous dwarf-shrubs. The only statistically significant interaction between vegetation type and fertilization was for grass cover, which increased twofold in forest understory but sixfold in tundra following fertilization. The lack of interactions for other variables suggests that the ground layers in these contrasting vegetation types have similar responses to fertilization. The nutrient-driven increase in grass cover and species-specific differences in productivity and root characters may alter ecosystem dynamics and C cycling in the long-term, but our study indicates that the response of birch forest understory and tundra vegetation may be consistent.\n
\n\n\n\n \n\n \n \n \n \n \n \n A simple experimental set-up to disentangle the effects of altered temperature and moisture regimes on soil organisms.\n \n \n \n \n\n\n \n Krab, E. J.; Cornelissen, J. H.; and Berg, M. P.\n\n\n \n\n\n\n Methods in Ecology and Evolution, 6(10): 1159–1168. October 2015.\n 00000\n\n\n\n
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\n\n\n@article{krab_simple_2015,\n\ttitle = {A simple experimental set-up to disentangle the effects of altered temperature and moisture regimes on soil organisms},\n\tvolume = {6},\n\tissn = {2041-210X},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12408/abstract},\n\tdoi = {10.1111/2041-210X.12408},\n\tabstract = {* Climate manipulation experiments in the field and laboratory incubations are common methods to study the impact of climate change on soils and their biota. However, both types of methods have drawbacks either on their mechanistic interpretation or ecological relevance.\n\n\n* We propose an experimental set-up that combines the best of both methods and can be easily obtained by modifying widely available Tullgren soil fauna extractors. This set-up creates or alters temperature and moisture gradients within intact field soil cores, after which soil biota, their activity and vertical movements can be studied. We assessed the performance and demonstrated the applicability of this set-up through a case study on Collembola response to changes in microclimatic gradients in peat bogs.\n\n\n* Warming created a vertical temperature gradient of 14°C in peat cores without varying soil moisture conditions, while at a given temperature regime, precipitation and drought treatments shifted natural soil moisture gradients to ‘wetter’ and ‘drier’, respectively. This allowed for disentangling interacting warming and moisture effects on soil fauna. In our case study, Collembola communities showed peat layer-specific responses to these climate treatments. Warming decreased Collembola density and altered community composition in the shallowest layer, whereas precipitation increase affected Collembola community composition in the deepest layer.\n\n\n* We showed that climate change can have layer-specific effects on soil organisms that are ‘hidden’ by not taking microclimatic vertical gradients into account. This experimental set-up facilitates studying (multitrophic) organism responses to climate changes, with only a small adjustment of equipment that is often already present in soil ecology laboratories. Moreover, this set-up can be easily customized to study many more other research questions related to wide-ranging organisms and ecosystems.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2017-02-08},\n\tjournal = {Methods in Ecology and Evolution},\n\tauthor = {Krab, Eveline J. and Cornelissen, Johannes H.C. and Berg, Matty P.},\n\tmonth = oct,\n\tyear = {2015},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Collembola, climate change, food web, laboratory, peat moss, soil cores, spatial vertical distribution},\n\tpages = {1159--1168},\n}\n\n\n\n\n\n * Climate manipulation experiments in the field and laboratory incubations are common methods to study the impact of climate change on soils and their biota. However, both types of methods have drawbacks either on their mechanistic interpretation or ecological relevance. * We propose an experimental set-up that combines the best of both methods and can be easily obtained by modifying widely available Tullgren soil fauna extractors. This set-up creates or alters temperature and moisture gradients within intact field soil cores, after which soil biota, their activity and vertical movements can be studied. We assessed the performance and demonstrated the applicability of this set-up through a case study on Collembola response to changes in microclimatic gradients in peat bogs. * Warming created a vertical temperature gradient of 14°C in peat cores without varying soil moisture conditions, while at a given temperature regime, precipitation and drought treatments shifted natural soil moisture gradients to ‘wetter’ and ‘drier’, respectively. This allowed for disentangling interacting warming and moisture effects on soil fauna. In our case study, Collembola communities showed peat layer-specific responses to these climate treatments. Warming decreased Collembola density and altered community composition in the shallowest layer, whereas precipitation increase affected Collembola community composition in the deepest layer. * We showed that climate change can have layer-specific effects on soil organisms that are ‘hidden’ by not taking microclimatic vertical gradients into account. This experimental set-up facilitates studying (multitrophic) organism responses to climate changes, with only a small adjustment of equipment that is often already present in soil ecology laboratories. Moreover, this set-up can be easily customized to study many more other research questions related to wide-ranging organisms and ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Direct and indirect effects of climate change on soil microbial and soil microbial-plant interactions: What lies ahead?.\n \n \n \n \n\n\n \n Classen, A. T.; Sundqvist, M. K.; Henning, J. A.; Newman, G. S.; Moore, J. A. M.; Cregger, M. A.; Moorhead, L. C.; and Patterson, C. M.\n\n\n \n\n\n\n Ecosphere, 6(8): 1–21. August 2015.\n 00019\n\n\n\n
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\n\n\n@article{classen_direct_2015,\n\ttitle = {Direct and indirect effects of climate change on soil microbial and soil microbial-plant interactions: {What} lies ahead?},\n\tvolume = {6},\n\tissn = {2150-8925},\n\tshorttitle = {Direct and indirect effects of climate change on soil microbial and soil microbial-plant interactions},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/ES15-00217.1/abstract},\n\tdoi = {10.1890/ES15-00217.1},\n\tabstract = {Global change is altering species distributions and thus interactions among organisms. Organisms live in concert with thousands of other species, some beneficial, some pathogenic, some which have little to no effect in complex communities. Since natural communities are composed of organisms with very different life history traits and dispersal ability it is unlikely they will all respond to climatic change in a similar way. Disjuncts in plant-pollinator and plant-herbivore interactions under global change have been relatively well described, but plant-soil microorganism and soil microbe-microbe relationships have received less attention. Since soil microorganisms regulate nutrient transformations, provide plants with nutrients, allow co-existence among neighbors, and control plant populations, changes in soil microorganism-plant interactions could have significant ramifications for plant community composition and ecosystem function. In this paper we explore how climatic change affects soil microbes and soil microbe-plant interactions directly and indirectly, discuss what we see as emerging and exciting questions and areas for future research, and discuss what ramifications changes in these interactions may have on the composition and function of ecosystems.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2017-02-10},\n\tjournal = {Ecosphere},\n\tauthor = {Classen, Aimée T. and Sundqvist, Maja K. and Henning, Jeremiah A. and Newman, Gregory S. and Moore, Jessica A. M. and Cregger, Melissa A. and Moorhead, Leigh C. and Patterson, Courtney M.},\n\tmonth = aug,\n\tyear = {2015},\n\tnote = {00019},\n\tkeywords = {\\#nosource, ESA Centennial Paper, Microbial community, Soil, Warming, bacteria, climate change, ecosystem, fungi, microbiome, plant-microbe interaction, plant-soil feedbacks, rhizosphere},\n\tpages = {1--21},\n}\n\n\n\n\n\n Global change is altering species distributions and thus interactions among organisms. Organisms live in concert with thousands of other species, some beneficial, some pathogenic, some which have little to no effect in complex communities. Since natural communities are composed of organisms with very different life history traits and dispersal ability it is unlikely they will all respond to climatic change in a similar way. Disjuncts in plant-pollinator and plant-herbivore interactions under global change have been relatively well described, but plant-soil microorganism and soil microbe-microbe relationships have received less attention. Since soil microorganisms regulate nutrient transformations, provide plants with nutrients, allow co-existence among neighbors, and control plant populations, changes in soil microorganism-plant interactions could have significant ramifications for plant community composition and ecosystem function. In this paper we explore how climatic change affects soil microbes and soil microbe-plant interactions directly and indirectly, discuss what we see as emerging and exciting questions and areas for future research, and discuss what ramifications changes in these interactions may have on the composition and function of ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Environmental Impacts—Freshwater Biogeochemistry.\n \n \n \n \n\n\n \n Humborg, C.; Andersen, H. E.; Blenckner, T.; Gadegast, M.; Giesler, R.; Hartmann, J.; Hugelius, G.; Hürdler, J.; Kortelainen, P.; Blicher-Mathiesen, G.; Venohr, M.; and Weyhenmeyer, G.\n\n\n \n\n\n\n In Team, T. B. I. A., editor(s), Second Assessment of Climate Change for the Baltic Sea Basin, pages 307–336. Springer International Publishing, 2015.\n 00000\n\n\n\n
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\n\n\n@incollection{humborg_environmental_2015,\n\ttitle = {Environmental {Impacts}—{Freshwater} {Biogeochemistry}},\n\tcopyright = {©2015 The Author(s)},\n\tisbn = {978-3-319-16005-4 978-3-319-16006-1},\n\turl = {http://link.springer.com/chapter/10.1007/978-3-319-16006-1_17},\n\tabstract = {Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to the Baltic Sea are not straight forward and are difficult to distinguish from other human drivers such as atmospheric deposition, forest and wetland management , eutrophication and hydrological alterations. Eutrophication is by far the most well-known factor affecting the biogeochemistry of the receiving waters in the various sub-basins of the Baltic Sea. However, the present literature review reveals that climate change is a compounding factor for all major drivers of freshwater biogeochemistry discussed here, although evidence is still often based on short-term and/or small-scale studies.},\n\tlanguage = {en},\n\turldate = {2017-02-07},\n\tbooktitle = {Second {Assessment} of {Climate} {Change} for the {Baltic} {Sea} {Basin}},\n\tpublisher = {Springer International Publishing},\n\tauthor = {Humborg, Christoph and Andersen, Hans Estrup and Blenckner, Thorsten and Gadegast, Mathias and Giesler, Reiner and Hartmann, Jens and Hugelius, Gustaf and Hürdler, Jens and Kortelainen, Pirkko and Blicher-Mathiesen, Gitte and Venohr, Markus and Weyhenmeyer, Gesa},\n\teditor = {Team, The BACC II Author},\n\tyear = {2015},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Atmospheric Sciences, Earth System Sciences},\n\tpages = {307--336},\n}\n\n\n\n\n\n Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to the Baltic Sea are not straight forward and are difficult to distinguish from other human drivers such as atmospheric deposition, forest and wetland management , eutrophication and hydrological alterations. Eutrophication is by far the most well-known factor affecting the biogeochemistry of the receiving waters in the various sub-basins of the Baltic Sea. However, the present literature review reveals that climate change is a compounding factor for all major drivers of freshwater biogeochemistry discussed here, although evidence is still often based on short-term and/or small-scale studies.\n
\n\n\n\n \n\n \n \n \n \n \n \n Environmental factors and traits that drive plant litter decomposition do not determine home‐field advantage effects.\n \n \n \n \n\n\n \n Veen, G. F. (.; Sundqvist, M. K.; and Wardle, D. A.\n\n\n \n\n\n\n Functional Ecology, 29(7): 981–991. July 2015.\n 00007\n\n\n\n
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\n\n\n@article{veen_environmental_2015,\n\ttitle = {Environmental factors and traits that drive plant litter decomposition do not determine home‐field advantage effects},\n\tvolume = {29},\n\tissn = {1365-2435},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12421/full},\n\tdoi = {10.1111/1365-2435.12421},\n\tabstract = {The ‘home‐field advantage’ (HFA) hypothesis predicts that plant litter is decomposed faster than expected underneath the plant from which it originates (‘home’) than underneath other plants (‘away’), because...},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-07},\n\tjournal = {Functional Ecology},\n\tauthor = {Veen, G. F. (Ciska) and Sundqvist, Maja K. and Wardle, David A.},\n\tmonth = jul,\n\tyear = {2015},\n\tnote = {00007},\n\tkeywords = {\\#nosource, global change, incubation conditions, litter–decomposer interactions, nutrient cycling, specialization, substrate quality},\n\tpages = {981--991},\n}\n\n\n\n\n\n The ‘home‐field advantage’ (HFA) hypothesis predicts that plant litter is decomposed faster than expected underneath the plant from which it originates (‘home’) than underneath other plants (‘away’), because...\n
\n\n\n\n \n\n \n \n \n \n \n \n Temperature sensitivity of heterotrophic soil CO2 production increases with increasing carbon substrate uptake rate.\n \n \n \n \n\n\n \n Erhagen, B.; Ilstedt, U.; and Nilsson, M. B.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 80: 45–52. January 2015.\n 00000\n\n\n\n
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\n\n\n@article{erhagen_temperature_2015,\n\ttitle = {Temperature sensitivity of heterotrophic soil {CO2} production increases with increasing carbon substrate uptake rate},\n\tvolume = {80},\n\tissn = {0038-0717},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0038071714003290},\n\tdoi = {10.1016/j.soilbio.2014.09.021},\n\tabstract = {Temperature profoundly affects saprotrophic respiration rates, and carbon quality theory predicts that the rates' temperature sensitivity should increase as the quality of the carbon source declines. However, reported relationships between saprotrophic respiration responses to temperature and carbon quality vary widely. Some of this variability may arise from confounding effects related to both substrate quality and substrate availability. The importance of these variables, as well as substrate diffusion and uptake rates, for the temperature sensitivity of saprotrophic respiration has been validated theoretically, but not empirically demonstrated. Thus, we tested effects of varying substrate uptake rates on the temperature sensitivity of organic carbon degradation.\n\nFor this purpose we created a model system using the organic layer (O-horizon), of a boreal forest soil, specifically to test effects of varying monomer uptake and release rates. The addition of both monomers and polymers generally increased the temperature sensitivity of saprotrophic respiration. In response to added monomers, there was a linear increase in the temperature sensitivity of both substrate-induced respiration and the specific growth rate with increasing rate of substrate uptake as indicated by the CO2 production at 14 °C. Both of these responses diverge from those predicted by the carbon quality theory, but they provide the first empirical evidence consistent with model predictions demonstrating increased temperature sensitivity with increased uptake rate of carbon monomers over the cell membrane. These results may explain why organic material of higher carbon quality induces higher temperature responses than lower carbon quality compounds, without contradicting carbon quality theory.},\n\turldate = {2014-10-20},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Erhagen, Björn and Ilstedt, Ulrik and Nilsson, Mats B.},\n\tmonth = jan,\n\tyear = {2015},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Decomposition, Q10, Soil organic carbon, Substrate availability, Substrate uptake, Temperature sensitivity},\n\tpages = {45--52},\n}\n\n\n\n\n\n Temperature profoundly affects saprotrophic respiration rates, and carbon quality theory predicts that the rates' temperature sensitivity should increase as the quality of the carbon source declines. However, reported relationships between saprotrophic respiration responses to temperature and carbon quality vary widely. Some of this variability may arise from confounding effects related to both substrate quality and substrate availability. The importance of these variables, as well as substrate diffusion and uptake rates, for the temperature sensitivity of saprotrophic respiration has been validated theoretically, but not empirically demonstrated. Thus, we tested effects of varying substrate uptake rates on the temperature sensitivity of organic carbon degradation. For this purpose we created a model system using the organic layer (O-horizon), of a boreal forest soil, specifically to test effects of varying monomer uptake and release rates. The addition of both monomers and polymers generally increased the temperature sensitivity of saprotrophic respiration. In response to added monomers, there was a linear increase in the temperature sensitivity of both substrate-induced respiration and the specific growth rate with increasing rate of substrate uptake as indicated by the CO2 production at 14 °C. Both of these responses diverge from those predicted by the carbon quality theory, but they provide the first empirical evidence consistent with model predictions demonstrating increased temperature sensitivity with increased uptake rate of carbon monomers over the cell membrane. These results may explain why organic material of higher carbon quality induces higher temperature responses than lower carbon quality compounds, without contradicting carbon quality theory.\n
\n\n\n\n \n\n \n \n \n \n \n \n Mammalian herbivores confer resilience of Arctic shrub-dominated ecosystems to changing climate.\n \n \n \n \n\n\n \n Kaarlejärvi, E.; Hoset, K. S.; and Olofsson, J.\n\n\n \n\n\n\n Global Change Biology, 21(9): 3379–3388. September 2015.\n 00009\n\n\n\n
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\n\n\n@article{kaarlejarvi_mammalian_2015,\n\ttitle = {Mammalian herbivores confer resilience of {Arctic} shrub-dominated ecosystems to changing climate},\n\tvolume = {21},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.12970/abstract},\n\tdoi = {10.1111/gcb.12970},\n\tabstract = {Climate change is resulting in a rapid expansion of shrubs in the Arctic. This expansion has been shown to be reinforced by positive feedbacks, and it could thus set the ecosystem on a trajectory toward an alternate, more productive regime. Herbivores, on the other hand, are known to counteract the effects of simultaneous climate warming on shrub biomass. However, little is known about the impact of herbivores on resilience of these ecosystems, that is, the capacity of a system to absorb disturbance and still remain in the same regime, retaining the same function, structure, and feedbacks. Here, we investigated how herbivores affect resilience of shrub-dominated systems to warming by studying the change of shrub biomass after a cessation of long-term experimental warming in a forest–tundra ecotone. As predicted, warming increased the biomass of shrubs, and in the absence of herbivores, shrub biomass in tundra continued to increase 4 years after cessation of the artificial warming, indicating that positive effects of warming on plant growth may persist even over a subsequent colder period. Herbivores contributed to the resilience of these systems by returning them back to the original low-biomass regime in both forest and tundra habitats. These results support the prediction that higher shrub biomass triggers positive feedbacks on soil processes and microclimate, which enable maintaining the rapid shrub growth even in colder climates. Furthermore, the results show that in our system, herbivores facilitate the resilience of shrub-dominated ecosystems to climate warming.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2017-02-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Kaarlejärvi, Elina and Hoset, Katrine S. and Olofsson, Johan},\n\tmonth = sep,\n\tyear = {2015},\n\tnote = {00009},\n\tkeywords = {\\#nosource, Lemmus, Microtus, Myodes, Rangifer, alternative stable state, climate warming, grazer, positive feedback, regime shift, tundra vegetation},\n\tpages = {3379--3388},\n}\n\n\n\n\n\n Climate change is resulting in a rapid expansion of shrubs in the Arctic. This expansion has been shown to be reinforced by positive feedbacks, and it could thus set the ecosystem on a trajectory toward an alternate, more productive regime. Herbivores, on the other hand, are known to counteract the effects of simultaneous climate warming on shrub biomass. However, little is known about the impact of herbivores on resilience of these ecosystems, that is, the capacity of a system to absorb disturbance and still remain in the same regime, retaining the same function, structure, and feedbacks. Here, we investigated how herbivores affect resilience of shrub-dominated systems to warming by studying the change of shrub biomass after a cessation of long-term experimental warming in a forest–tundra ecotone. As predicted, warming increased the biomass of shrubs, and in the absence of herbivores, shrub biomass in tundra continued to increase 4 years after cessation of the artificial warming, indicating that positive effects of warming on plant growth may persist even over a subsequent colder period. Herbivores contributed to the resilience of these systems by returning them back to the original low-biomass regime in both forest and tundra habitats. These results support the prediction that higher shrub biomass triggers positive feedbacks on soil processes and microclimate, which enable maintaining the rapid shrub growth even in colder climates. Furthermore, the results show that in our system, herbivores facilitate the resilience of shrub-dominated ecosystems to climate warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Terrestrial organic matter input suppresses biomass production in lake ecosystems.\n \n \n \n \n\n\n \n Karlsson, J.; Bergström, A.; Byström, P.; Gudasz, C.; Rodríguez, P.; and Hein, C.\n\n\n \n\n\n\n Ecology, 96(11): 2870–2876. November 2015.\n 00015\n\n\n\n
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\n\n\n@article{karlsson_terrestrial_2015,\n\ttitle = {Terrestrial organic matter input suppresses biomass production in lake ecosystems},\n\tvolume = {96},\n\tissn = {1939-9170},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/15-0515.1/abstract},\n\tdoi = {10.1890/15-0515.1},\n\tabstract = {Terrestrial ecosystems export large amounts of organic carbon (t-OC) but the net effect of this OC on the productivity of recipient aquatic ecosystems is largely unknown. In this study of boreal lakes, we show that the relative contribution of t-OC to individual top consumer (fish) biomass production, and to most of their potential prey organisms, increased with the concentration of dissolved organic carbon (DOC; dominated by t-OC sources) in water. However, the biomass and production of top consumers decreased with increasing concentration of DOC, despite their substantial use (up to 60\\%) of t-OC. Thus, the results suggest that although t-OC supports individual consumer growth in lakes to a large extent, t-OC input suppresses rather than subsidizes population biomass production.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2017-02-06},\n\tjournal = {Ecology},\n\tauthor = {Karlsson, Jan and Bergström, Ann-Kristin and Byström, Pär and Gudasz, Cristian and Rodríguez, Patricia and Hein, Catherine},\n\tmonth = nov,\n\tyear = {2015},\n\tnote = {00015},\n\tkeywords = {\\#nosource, Umeå, Sweden, allochthonous organic matter, boreal lakes, lake ecosystem, productivity, subsidy, terrestrial organic carbon, t-OC},\n\tpages = {2870--2876},\n}\n\n\n\n\n\n Terrestrial ecosystems export large amounts of organic carbon (t-OC) but the net effect of this OC on the productivity of recipient aquatic ecosystems is largely unknown. In this study of boreal lakes, we show that the relative contribution of t-OC to individual top consumer (fish) biomass production, and to most of their potential prey organisms, increased with the concentration of dissolved organic carbon (DOC; dominated by t-OC sources) in water. However, the biomass and production of top consumers decreased with increasing concentration of DOC, despite their substantial use (up to 60%) of t-OC. Thus, the results suggest that although t-OC supports individual consumer growth in lakes to a large extent, t-OC input suppresses rather than subsidizes population biomass production.\n
\n\n\n\n \n\n \n \n \n \n \n \n N-limited consumer growth and low nutrient regeneration N:P ratios in lakes with low N deposition.\n \n \n \n \n\n\n \n Bergström, A.; Karlsson, D.; Karlsson, J.; and Vrede, T.\n\n\n \n\n\n\n Ecosphere, 6(1): 1–13. January 2015.\n \n\n\n\n
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\n\n\n@article{bergstrom_n-limited_2015,\n\ttitle = {N-limited consumer growth and low nutrient regeneration {N}:{P} ratios in lakes with low {N} deposition},\n\tvolume = {6},\n\tissn = {2150-8925},\n\tshorttitle = {N-limited consumer growth and low nutrient regeneration {N}},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/ES14-00333.1/abstract},\n\tdoi = {10.1890/ES14-00333.1},\n\tabstract = {Nutrient limitation of primary producers and their consumers can have a large influence on ecosystem productivity. The nature and strength of nutrient limitation is driven both by external factors (e.g., nutrient loading) and internal processes (e.g., consumer-driven nutrient regeneration). Here we present results from a field study in 10 low productive headwater lakes in northern subarctic Sweden, where nitrogen (N) deposition is low and phytoplankton is primarily N-limited. We assessed the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of seston and zooplankton and estimated the N:P ratio of consumer-driven nutrient regeneration. Based on stoichiometric models, the estimated elemental imbalances between seston and zooplankton suggest that zooplankton were mainly N-limited and regenerated nutrients with low N:P ratios (median 11.9, atomic ratio). The predicted N:P regeneration ratios were consistent with results from phytoplankton nutrient limitation bioassays in mid-summer, i.e., the N:P regeneration was predicted to be low when phytoplankton were N-limited, and high when phytoplankton were P-limited. During other seasons, when water discharge was high, nutrient loading from the surrounding catchments apparently had the strongest effect on phytoplankton nutrient limitation. We propose that lakes with higher N:P ratios than the open ocean is an effect of N deposition, that N-limitation of consumers and phytoplankton is further enhanced by low nutrient regeneration N:P ratios, and that in the absence of N deposition, lake and ocean N:P stoichiometry are similar.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-06},\n\tjournal = {Ecosphere},\n\tauthor = {Bergström, Ann-Kristin and Karlsson, Daniel and Karlsson, Jan and Vrede, Tobias},\n\tmonth = jan,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Nitrogen, consumer driven nutrient cycling, ecological stoichiometry, nutrient limitation, phosphorus, phytoplankton, zooplankton},\n\tpages = {1--13},\n}\n\n\n\n\n\n Nutrient limitation of primary producers and their consumers can have a large influence on ecosystem productivity. The nature and strength of nutrient limitation is driven both by external factors (e.g., nutrient loading) and internal processes (e.g., consumer-driven nutrient regeneration). Here we present results from a field study in 10 low productive headwater lakes in northern subarctic Sweden, where nitrogen (N) deposition is low and phytoplankton is primarily N-limited. We assessed the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of seston and zooplankton and estimated the N:P ratio of consumer-driven nutrient regeneration. Based on stoichiometric models, the estimated elemental imbalances between seston and zooplankton suggest that zooplankton were mainly N-limited and regenerated nutrients with low N:P ratios (median 11.9, atomic ratio). The predicted N:P regeneration ratios were consistent with results from phytoplankton nutrient limitation bioassays in mid-summer, i.e., the N:P regeneration was predicted to be low when phytoplankton were N-limited, and high when phytoplankton were P-limited. During other seasons, when water discharge was high, nutrient loading from the surrounding catchments apparently had the strongest effect on phytoplankton nutrient limitation. We propose that lakes with higher N:P ratios than the open ocean is an effect of N deposition, that N-limitation of consumers and phytoplankton is further enhanced by low nutrient regeneration N:P ratios, and that in the absence of N deposition, lake and ocean N:P stoichiometry are similar.\n
\n\n\n\n \n\n \n \n \n \n \n \n Decadal warming causes a consistent and persistent shift from heterotrophic to autotrophic respiration in contrasting permafrost ecosystems.\n \n \n \n \n\n\n \n Hicks Pries, C. E.; van Logtestijn, R. S. P.; Schuur, E. A. G.; Natali, S. M.; Cornelissen, J. H. C.; Aerts, R.; and Dorrepaal, E.\n\n\n \n\n\n\n Global Change Biology, 21(12): 4508–4519. December 2015.\n \n\n\n\n
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\n\n\n@article{hicks_pries_decadal_2015,\n\ttitle = {Decadal warming causes a consistent and persistent shift from heterotrophic to autotrophic respiration in contrasting permafrost ecosystems},\n\tvolume = {21},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.13032/abstract},\n\tdoi = {10.1111/gcb.13032},\n\tabstract = {Soil carbon in permafrost ecosystems has the potential to become a major positive feedback to climate change if permafrost thaw increases heterotrophic decomposition. However, warming can also stimulate autotrophic production leading to increased ecosystem carbon storage—a negative climate change feedback. Few studies partitioning ecosystem respiration examine decadal warming effects or compare responses among ecosystems. Here, we first examined how 11 years of warming during different seasons affected autotrophic and heterotrophic respiration in a bryophyte-dominated peatland in Abisko, Sweden. We used natural abundance radiocarbon to partition ecosystem respiration into autotrophic respiration, associated with production, and heterotrophic decomposition. Summertime warming decreased the age of carbon respired by the ecosystem due to increased proportional contributions from autotrophic and young soil respiration and decreased proportional contributions from old soil. Summertime warming's large effect was due to not only warmer air temperatures during the growing season, but also to warmer deep soils year-round. Second, we compared ecosystem respiration responses between two contrasting ecosystems, the Abisko peatland and a tussock-dominated tundra in Healy, Alaska. Each ecosystem had two different timescales of warming ({\\textless}5 years and over a decade). Despite the Abisko peatland having greater ecosystem respiration and larger contributions from heterotrophic respiration than the Healy tundra, both systems responded consistently to short- and long-term warming with increased respiration, increased autotrophic contributions to ecosystem respiration, and increased ratios of autotrophic to heterotrophic respiration. We did not detect an increase in old soil carbon losses with warming at either site. If increased autotrophic respiration is balanced by increased primary production, as is the case in the Healy tundra, warming will not cause these ecosystems to become growing season carbon sources. Warming instead causes a persistent shift from heterotrophic to more autotrophic control of the growing season carbon cycle in these carbon-rich permafrost ecosystems.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Hicks Pries, Caitlin E. and van Logtestijn, Richard S. P. and Schuur, Edward A. G. and Natali, Susan M. and Cornelissen, Johannes H. C. and Aerts, Rien and Dorrepaal, Ellen},\n\tmonth = dec,\n\tyear = {2015},\n\tkeywords = {\\#nosource, autotrophic, carbon, climate change feedback, ecosystem respiration, heterotrophic, permafrost thaw, radiocarbon, warming experiment},\n\tpages = {4508--4519},\n}\n\n\n\n\n\n Soil carbon in permafrost ecosystems has the potential to become a major positive feedback to climate change if permafrost thaw increases heterotrophic decomposition. However, warming can also stimulate autotrophic production leading to increased ecosystem carbon storage—a negative climate change feedback. Few studies partitioning ecosystem respiration examine decadal warming effects or compare responses among ecosystems. Here, we first examined how 11 years of warming during different seasons affected autotrophic and heterotrophic respiration in a bryophyte-dominated peatland in Abisko, Sweden. We used natural abundance radiocarbon to partition ecosystem respiration into autotrophic respiration, associated with production, and heterotrophic decomposition. Summertime warming decreased the age of carbon respired by the ecosystem due to increased proportional contributions from autotrophic and young soil respiration and decreased proportional contributions from old soil. Summertime warming's large effect was due to not only warmer air temperatures during the growing season, but also to warmer deep soils year-round. Second, we compared ecosystem respiration responses between two contrasting ecosystems, the Abisko peatland and a tussock-dominated tundra in Healy, Alaska. Each ecosystem had two different timescales of warming (\\textless5 years and over a decade). Despite the Abisko peatland having greater ecosystem respiration and larger contributions from heterotrophic respiration than the Healy tundra, both systems responded consistently to short- and long-term warming with increased respiration, increased autotrophic contributions to ecosystem respiration, and increased ratios of autotrophic to heterotrophic respiration. We did not detect an increase in old soil carbon losses with warming at either site. If increased autotrophic respiration is balanced by increased primary production, as is the case in the Healy tundra, warming will not cause these ecosystems to become growing season carbon sources. Warming instead causes a persistent shift from heterotrophic to more autotrophic control of the growing season carbon cycle in these carbon-rich permafrost ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems.\n \n \n \n\n\n \n Vonk, J. E.; Tank, S. E.; Bowden, W. B.; Laurion, I.; Vincent, W. F.; Alekseychik, P.; Amyot, M.; Billet, M. F.; Canario, J.; Cory, R. M.; Deshpande, B. N.; Helbig, M.; Jammet, M.; Karlsson, J.; Larouche, J.; MacMillan, G.; Rautio, M.; Anthony, K. M. W.; and Wickland, K. P.\n\n\n \n\n\n\n Biogeosciences, 12(23): 7129–7167. 2015.\n \n\n\n\n
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\n\n\n@article{vonk_reviews_2015,\n\ttitle = {Reviews and syntheses: {Effects} of permafrost thaw on {Arctic} aquatic ecosystems},\n\tvolume = {12},\n\tissn = {1726-4170},\n\tshorttitle = {Reviews and syntheses},\n\tdoi = {10.5194/bg-12-7129-2015},\n\tabstract = {The Arctic is a water-rich region, with freshwater systems covering about 16\\% of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO2 and CH4), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to quantify how permafrost thaw is affecting aquatic ecosystems across diverse Arctic landscapes, and the implications of this change for further climate warming.},\n\tlanguage = {English},\n\tnumber = {23},\n\tjournal = {Biogeosciences},\n\tauthor = {Vonk, J. E. and Tank, S. E. and Bowden, W. B. and Laurion, I. and Vincent, W. F. and Alekseychik, P. and Amyot, M. and Billet, M. F. and Canario, J. and Cory, R. M. and Deshpande, B. N. and Helbig, M. and Jammet, M. and Karlsson, J. and Larouche, J. and MacMillan, G. and Rautio, M. and Anthony, K. M. Walter and Wickland, K. P.},\n\tyear = {2015},\n\tkeywords = {\\#nosource, boreal catchment underlain, carbon-dioxide emissions, climate-change, dissolved organic-matter, eddy covariance measurements, fresh-water ecosystems, greenhouse-gas emissions, high-latitude lakes, lena river delta, western siberia},\n\tpages = {7129--7167},\n}\n\n\n\n\n\n The Arctic is a water-rich region, with freshwater systems covering about 16% of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO2 and CH4), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to quantify how permafrost thaw is affecting aquatic ecosystems across diverse Arctic landscapes, and the implications of this change for further climate warming.\n
\n\n\n\n \n\n \n \n \n \n \n The influence of dissolved organic carbon on primary production in northern lakes.\n \n \n \n\n\n \n Seekell, D. A.; Lapierre, J.; Ask, J.; Bergstroem, A.; Deininger, A.; Rodriguez, P.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 60(4): 1276–1285. July 2015.\n \n\n\n\n
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\n\n\n@article{seekell_influence_2015,\n\ttitle = {The influence of dissolved organic carbon on primary production in northern lakes},\n\tvolume = {60},\n\tissn = {0024-3590},\n\tdoi = {10.1002/lno.10096},\n\tabstract = {Dissolved organic carbon (DOC) concentrations in lakes are changing globally, but little is known about potential ecosystem impacts.We evaluated the relationship between DOC and whole-lake primary production in arctic and boreal lakes. Both light extinction (inhibits primary production) and nutrient availability (stimulates primary production) are positively and nonlinearly related to DOC concentration. These nonlinearities create a threshold DOC concentration (4.8mg L-1), below which the DOC-primary production relationship is positive, and above which the relationship is negative. DOC concentration varies maximally between regions, creating a unimodal relationship between primary production and DOC that emerges at broader scales because arctic lakes largely fall below the threshold DOC concentration, but boreal lakes fall above it. Our analysis suggests that the impact of DOC trends on lake primary production will vary across lakes and regions as a result of contrasting baseline conditions relative to the DOC threshold.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Seekell, David A. and Lapierre, Jean-Francois and Ask, Jenny and Bergstroem, Ann-Kristin and Deininger, Anne and Rodriguez, Patricia and Karlsson, Jan},\n\tmonth = jul,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Ecosystems, humic lakes, light, matter, nitrogen deposition, nutrient limitation, pelagic habitats, phytoplankton biomass, sub-arctic lakes, swedish lakes},\n\tpages = {1276--1285},\n}\n\n\n\n\n\n Dissolved organic carbon (DOC) concentrations in lakes are changing globally, but little is known about potential ecosystem impacts.We evaluated the relationship between DOC and whole-lake primary production in arctic and boreal lakes. Both light extinction (inhibits primary production) and nutrient availability (stimulates primary production) are positively and nonlinearly related to DOC concentration. These nonlinearities create a threshold DOC concentration (4.8mg L-1), below which the DOC-primary production relationship is positive, and above which the relationship is negative. DOC concentration varies maximally between regions, creating a unimodal relationship between primary production and DOC that emerges at broader scales because arctic lakes largely fall below the threshold DOC concentration, but boreal lakes fall above it. Our analysis suggests that the impact of DOC trends on lake primary production will vary across lakes and regions as a result of contrasting baseline conditions relative to the DOC threshold.\n
\n\n\n\n \n\n \n \n \n \n \n Size and characteristics of the DOC pool in near-surface subarctic mire permafrost as a potential source for nearby freshwaters.\n \n \n \n\n\n \n Thompson, M. S.; Giesler, R.; Karlsson, J.; and Klaminder, J.\n\n\n \n\n\n\n Arctic Antarctic and Alpine Research, 47(1): 49–58. February 2015.\n 00000\n\n\n\n
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\n\n\n@article{thompson_size_2015,\n\ttitle = {Size and characteristics of the {DOC} pool in near-surface subarctic mire permafrost as a potential source for nearby freshwaters},\n\tvolume = {47},\n\tissn = {1523-0430},\n\tdoi = {10.1657/AAAR0014-010},\n\tabstract = {Subarctic peatlands are rich sources of organic carbon for freshwater ecosystems. Where those peatlands are underlain by permafrost, permafrost thaw may cause an initial release of bioavailable dissolved organic carbon (DOC) to surrounding freshwaters. In this study, we measured icebound and potentially leachable (extracted) DOC quantities and indices of DOC quality in active layer and permafrost layers from two subarctic peat mires, Stord-alen and Storflaket. Most of the permafrost layers did not contain more organic matter or exportable DOC (as g kg(-1) dry soil) than the overlying active layer, and there was no difference in aromaticity, molecular weight, or the ratio between labile and recalcitrant DOC extracted from the permafrost and active layer. However, DOC held in segregated ice of the near-surface permafrost had relatively low aromaticity compared to extracted DOC from the same depth. Total icebound and potentially leachable DOC in the Stordalen mire permafrost that is predicted to experience active layer deepening during each of the next 50 years corresponded to about 0.1\\% of the current annual aquatic export of DOC from the mire. We conclude that the pool of potentially leachable DOC currently stored in permafrost layers is small. We also highlight differences in permafrost organic material between the two studied mire systems, which has an effect on the pool and properties of leachable DOC that is potentially available for export during thaw. Moreover, the geomorphological form of permafrost thaw will influence future hydrological connectedness and DOC production, in turn determining future DOC export from the mires.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Arctic Antarctic and Alpine Research},\n\tauthor = {Thompson, M. S. and Giesler, R. and Karlsson, J. and Klaminder, J.},\n\tmonth = feb,\n\tyear = {2015},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Biogeochemistry, canada, carbon, climate-change, dissolved organic-matter, ground ice, indicators, northwest-territories, soils, streams},\n\tpages = {49--58},\n}\n\n\n\n\n\n Subarctic peatlands are rich sources of organic carbon for freshwater ecosystems. Where those peatlands are underlain by permafrost, permafrost thaw may cause an initial release of bioavailable dissolved organic carbon (DOC) to surrounding freshwaters. In this study, we measured icebound and potentially leachable (extracted) DOC quantities and indices of DOC quality in active layer and permafrost layers from two subarctic peat mires, Stord-alen and Storflaket. Most of the permafrost layers did not contain more organic matter or exportable DOC (as g kg(-1) dry soil) than the overlying active layer, and there was no difference in aromaticity, molecular weight, or the ratio between labile and recalcitrant DOC extracted from the permafrost and active layer. However, DOC held in segregated ice of the near-surface permafrost had relatively low aromaticity compared to extracted DOC from the same depth. Total icebound and potentially leachable DOC in the Stordalen mire permafrost that is predicted to experience active layer deepening during each of the next 50 years corresponded to about 0.1% of the current annual aquatic export of DOC from the mire. We conclude that the pool of potentially leachable DOC currently stored in permafrost layers is small. We also highlight differences in permafrost organic material between the two studied mire systems, which has an effect on the pool and properties of leachable DOC that is potentially available for export during thaw. Moreover, the geomorphological form of permafrost thaw will influence future hydrological connectedness and DOC production, in turn determining future DOC export from the mires.\n
\n\n\n\n \n\n \n \n \n \n \n Climate change modifies the size structure of assemblages of emerging aquatic insects.\n \n \n \n\n\n \n Jonsson, M.; Hedström, P.; Stenroth, K.; Hotchkiss, E. R.; Vasconcelos, F. R.; Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Freshwater Biology, 60(1): 78–88. January 2015.\n \n\n\n\n
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\n\n\n@article{jonsson_climate_2015,\n\ttitle = {Climate change modifies the size structure of assemblages of emerging aquatic insects},\n\tvolume = {60},\n\tissn = {0046-5070},\n\tdoi = {10.1111/fwb.12468},\n\tabstract = {Climate change is expected to not only raise water temperatures, but also to cause brownification of aquatic ecosystems via increased inputs of terrestrial dissolved organic matter. While efforts have been made to understand how increased temperature and brownification separately influence aquatic food webs, their interactive effects have been less investigated. Further, although climate change effects on aquatic ecosystems likely will propagate to terrestrial consumers via changes in aquatic insect emergence, this has rarely been studied. We investigated the effect of climate change on aquatic insect emergence, in a large-scale outdoor pond facility where 16 sections - each containing natural food webs including a fish top-consumer population - were subjected to warming (3 degrees C above ambient temperatures) and/or brownification (by adding naturally humic stream water). Aquatic insect emergence was measured biweekly over 18weeks. We found no effect of warming or brownification on total emergent insect dry mass. However, warming significantly reduced the number of emergent Chironomidae, while numbers of larger taxa, Trichoptera and Ephemeroptera, remained unchanged. On average, 57\\% and 58\\% fewer Chironomidae emerged from the warmed clear and humic pond sections, respectively. This substantial decrease in emergent Chironomidae resulted in a changed community structure and on average larger individuals emerging from warm sections as well as from humic sections under ambient conditions. There was also a weak influence of fish biomass on the size structure of emergent aquatic insects, with a positive relationship between individual insect size and total fish biomass, but effects of fish were clearly subordinate to those of warming. Climate change impacts on aquatic systems can have widespread consequences also for terrestrial systems, as aquatic insects are ubiquitous and their emergence represents an important resource flow from aquatic to terrestrial environments. While we found that neither warming nor brownification quantitatively changed total aquatic insect emergence biomass, the warming-induced decrease in number of emergent Chironomidae and the subsequent increase in average body size will likely impact terrestrial consumers relying on emergent aquatic insect as prey.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Freshwater Biology},\n\tauthor = {Jonsson, Micael and Hedström, Per and Stenroth, Karolina and Hotchkiss, Erin R. and Vasconcelos, Francisco Rivera and Karlsson, Jan and Byström, Pär},\n\tmonth = jan,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Warming, aquatic subsidies, brownification, dissolved organic matter, dissolved organic-carbon, fish predation, gas-exchange, lakes, pond ecosystems, predation alters, prey, stream, subsidy, terrestrial food webs, water},\n\tpages = {78--88},\n}\n\n\n\n\n\n Climate change is expected to not only raise water temperatures, but also to cause brownification of aquatic ecosystems via increased inputs of terrestrial dissolved organic matter. While efforts have been made to understand how increased temperature and brownification separately influence aquatic food webs, their interactive effects have been less investigated. Further, although climate change effects on aquatic ecosystems likely will propagate to terrestrial consumers via changes in aquatic insect emergence, this has rarely been studied. We investigated the effect of climate change on aquatic insect emergence, in a large-scale outdoor pond facility where 16 sections - each containing natural food webs including a fish top-consumer population - were subjected to warming (3 degrees C above ambient temperatures) and/or brownification (by adding naturally humic stream water). Aquatic insect emergence was measured biweekly over 18weeks. We found no effect of warming or brownification on total emergent insect dry mass. However, warming significantly reduced the number of emergent Chironomidae, while numbers of larger taxa, Trichoptera and Ephemeroptera, remained unchanged. On average, 57% and 58% fewer Chironomidae emerged from the warmed clear and humic pond sections, respectively. This substantial decrease in emergent Chironomidae resulted in a changed community structure and on average larger individuals emerging from warm sections as well as from humic sections under ambient conditions. There was also a weak influence of fish biomass on the size structure of emergent aquatic insects, with a positive relationship between individual insect size and total fish biomass, but effects of fish were clearly subordinate to those of warming. Climate change impacts on aquatic systems can have widespread consequences also for terrestrial systems, as aquatic insects are ubiquitous and their emergence represents an important resource flow from aquatic to terrestrial environments. While we found that neither warming nor brownification quantitatively changed total aquatic insect emergence biomass, the warming-induced decrease in number of emergent Chironomidae and the subsequent increase in average body size will likely impact terrestrial consumers relying on emergent aquatic insect as prey.\n
\n\n\n\n \n\n \n \n \n \n \n \n Long-term reindeer grazing limits warming-induced increases in CO 2 released by tundra heath soil: potential role of soil C quality.\n \n \n \n \n\n\n \n Väisänen, M.; Sjögersten, S.; Large, D.; Drage, T.; and Stark, S.\n\n\n \n\n\n\n Environmental Research Letters, 10(9): 094020. 2015.\n \n\n\n\n
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\n\n\n@article{vaisanen_long-term_2015,\n\ttitle = {Long-term reindeer grazing limits warming-induced increases in {CO} 2 released by tundra heath soil: potential role of soil {C} quality},\n\tvolume = {10},\n\tissn = {1748-9326},\n\tshorttitle = {Long-term reindeer grazing limits warming-induced increases in {CO} 2 released by tundra heath soil},\n\turl = {http://stacks.iop.org/1748-9326/10/i=9/a=094020},\n\tdoi = {10.1088/1748-9326/10/9/094020},\n\tabstract = {The current climate warming in the Arctic may increase the microbial degradation of vast pools of soil carbon (C); however, the temperature sensitivity of decomposition is often highly dependent on the quality of accumulated soil C. Grazing by reindeer ( Rangifer tarandus L.) substantially affects the dominant vegetation and often increases graminoids in relation to dwarf shrubs in ecosystems, but the effect of this vegetation shift on the soil C quality has not been previously investigated. We analyzed the soil C quality and rate of microbially mediated CO 2 release at different temperatures in long-term laboratory incubations using soils from lightly grazed dwarf shrub-dominated and heavily grazed graminoid-dominated tundra ecosystem. The soil C quality was characterized by solid-state cross-polarization magic angle spinning (CPMAS 13 C NMR) spectroscopy, which showed a higher relative proportion of carbohydrate C under light grazing and higher relative proportion of aliphatic not-O-substituted C under heavy grazing. Initial measurements showed lower temperature sensitivity of the CO 2 release in soils under light grazing compared with soil under heavy grazing, but the overall CO 2 release rate and its temperature sensitivity increased under light grazing as the soil incubation progressed. At the end of incubation, significantly more carbohydrate C had been lost in soils under light grazing compared with heavy grazing. These findings indicate that there may be a link between the grazer-induced effects on soil C quality and the potential of soils to release CO 2 to atmosphere. We suggest that vegetation shifts induced by grazing could influence the proportion of accumulated soil C that is vulnerable to microbial degradation under warming climate.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2017-05-27},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Väisänen, Maria and Sjögersten, Sofie and Large, David and Drage, Trevor and Stark, Sari},\n\tyear = {2015},\n\tkeywords = {\\#nosource},\n\tpages = {094020},\n}\n\n\n\n\n\n The current climate warming in the Arctic may increase the microbial degradation of vast pools of soil carbon (C); however, the temperature sensitivity of decomposition is often highly dependent on the quality of accumulated soil C. Grazing by reindeer ( Rangifer tarandus L.) substantially affects the dominant vegetation and often increases graminoids in relation to dwarf shrubs in ecosystems, but the effect of this vegetation shift on the soil C quality has not been previously investigated. We analyzed the soil C quality and rate of microbially mediated CO 2 release at different temperatures in long-term laboratory incubations using soils from lightly grazed dwarf shrub-dominated and heavily grazed graminoid-dominated tundra ecosystem. The soil C quality was characterized by solid-state cross-polarization magic angle spinning (CPMAS 13 C NMR) spectroscopy, which showed a higher relative proportion of carbohydrate C under light grazing and higher relative proportion of aliphatic not-O-substituted C under heavy grazing. Initial measurements showed lower temperature sensitivity of the CO 2 release in soils under light grazing compared with soil under heavy grazing, but the overall CO 2 release rate and its temperature sensitivity increased under light grazing as the soil incubation progressed. At the end of incubation, significantly more carbohydrate C had been lost in soils under light grazing compared with heavy grazing. These findings indicate that there may be a link between the grazer-induced effects on soil C quality and the potential of soils to release CO 2 to atmosphere. We suggest that vegetation shifts induced by grazing could influence the proportion of accumulated soil C that is vulnerable to microbial degradation under warming climate.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon dioxide evasion from headwater systems strongly contributes to the total export of carbon from a small boreal lake catchment.\n \n \n \n \n\n\n \n Kokic, J.; Wallin, M. B.; Chmiel, H. E.; Denfeld, B. A.; and Sobek, S.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 120(1): 2014JG002706. January 2015.\n \n\n\n\n
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\n\n\n@article{kokic_carbon_2015,\n\ttitle = {Carbon dioxide evasion from headwater systems strongly contributes to the total export of carbon from a small boreal lake catchment},\n\tvolume = {120},\n\tissn = {2169-8961},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/2014JG002706/abstract},\n\tdoi = {10.1002/2014JG002706},\n\tabstract = {Inland waters are hotspots for carbon (C) cycling and therefore important for landscape C budgets. Small streams and lakes are particularly important; however, quantifying C fluxes is difficult and has rarely been done for the entire aquatic continuum, composed of connected streams and lakes within the same catchment. We investigated carbon dioxide (CO2) evasion and fluvial fluxes of dissolved inorganic carbon and dissolved organic carbon (DIC and DOC) in stream and lake systems within the 2.3 km2 catchment of a small boreal lake. Our results show pronounced spatial and temporal variability in C fluxes even at a small spatial scale. C loss from the catchment through CO2 evasion from headwaters for the total open water-sampling period was 9.7 g C m−2 catchment, dominating the total catchment C loss (including CO2 evasion, DIC, and DOC export from the lake, which were 2.7, 0.2, and 5.2 g C m−2 catchment, respectively). Aquatic CO2 evasion was dominated by headwater streams that occupy {\\textasciitilde}0.1\\% of the catchment but contributed 65\\% to the total aquatic CO2 evasion from the catchment. The importance of streams was mainly an effect of the higher gas transfer velocities than compared to lakes (median, 67 and 2.2 cm h−1, respectively). Accurately estimating the contribution of C fluxes from headwater streams, particularly the temporal and spatial dynamics in their gas transfer velocity, is key to landscape-scale C budgets. This study demonstrates that CO2 evasion from headwaters can be the major pathway of C loss from boreal catchments, even at a small spatial scale.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-05-27},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Kokic, Jovana and Wallin, Marcus B. and Chmiel, Hannah E. and Denfeld, Blaize A. and Sobek, Sebastian},\n\tmonth = jan,\n\tyear = {2015},\n\tkeywords = {\\#nosource, 0426 Biosphere/atmosphere interactions, 0428 Carbon cycling, 0458 Limnology, carbon dioxide evasion, carbon flux, gas transfer velocity, small lakes, streams},\n\tpages = {2014JG002706},\n}\n\n\n\n\n\n Inland waters are hotspots for carbon (C) cycling and therefore important for landscape C budgets. Small streams and lakes are particularly important; however, quantifying C fluxes is difficult and has rarely been done for the entire aquatic continuum, composed of connected streams and lakes within the same catchment. We investigated carbon dioxide (CO2) evasion and fluvial fluxes of dissolved inorganic carbon and dissolved organic carbon (DIC and DOC) in stream and lake systems within the 2.3 km2 catchment of a small boreal lake. Our results show pronounced spatial and temporal variability in C fluxes even at a small spatial scale. C loss from the catchment through CO2 evasion from headwaters for the total open water-sampling period was 9.7 g C m−2 catchment, dominating the total catchment C loss (including CO2 evasion, DIC, and DOC export from the lake, which were 2.7, 0.2, and 5.2 g C m−2 catchment, respectively). Aquatic CO2 evasion was dominated by headwater streams that occupy ~0.1% of the catchment but contributed 65% to the total aquatic CO2 evasion from the catchment. The importance of streams was mainly an effect of the higher gas transfer velocities than compared to lakes (median, 67 and 2.2 cm h−1, respectively). Accurately estimating the contribution of C fluxes from headwater streams, particularly the temporal and spatial dynamics in their gas transfer velocity, is key to landscape-scale C budgets. This study demonstrates that CO2 evasion from headwaters can be the major pathway of C loss from boreal catchments, even at a small spatial scale.\n
\n\n\n\n \n\n \n \n \n \n \n Large difference in carbon emission - burial balances between boreal and arctic lakes.\n \n \n \n\n\n \n Lundin, E. J.; Klaminder, J.; Bastviken, D.; Olid, C.; Hansson, S. V.; and Karlsson, J.\n\n\n \n\n\n\n Scientific Reports, 5(5): 14248. 2015.\n 00005\n\n\n\n
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\n\n\n@article{lundin_large_2015,\n\ttitle = {Large difference in carbon emission - burial balances between boreal and arctic lakes},\n\tvolume = {5},\n\tissn = {2045-2322},\n\tdoi = {10.1038/srep14248},\n\tabstract = {Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths and control of these fundamentally different pathways are therefore of interest when assessing the continental C balance and its response to environmental change. In this study, based on new high-resolution estimates in combination with literature data, we show that annual emission: burial ratios are generally ten times higher in boreal compared to subarctic - arctic lakes. These results suggest major differences in lake C cycling between biomes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Such effects are of major importance for understanding climatic feedbacks on the continental C sink - source function at high latitudes. If predictions of global warming and northward expansion of the boreal biome are correct, it is likely that increasing C emissions from high latitude lakes will partly counteract the presumed increasing terrestrial C sink capacity at high latitudes.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Scientific Reports},\n\tauthor = {Lundin, E. J. and Klaminder, J. and Bastviken, D. and Olid, C. and Hansson, S. V. and Karlsson, J.},\n\tyear = {2015},\n\tnote = {00005},\n\tkeywords = {\\#nosource, Ecosystems, Mineralization, atmosphere, deposition, dioxide, limitation, organic-carbon, sediments, soils, vegetation},\n\tpages = {14248},\n}\n\n\n\n\n\n Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths and control of these fundamentally different pathways are therefore of interest when assessing the continental C balance and its response to environmental change. In this study, based on new high-resolution estimates in combination with literature data, we show that annual emission: burial ratios are generally ten times higher in boreal compared to subarctic - arctic lakes. These results suggest major differences in lake C cycling between biomes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Such effects are of major importance for understanding climatic feedbacks on the continental C sink - source function at high latitudes. If predictions of global warming and northward expansion of the boreal biome are correct, it is likely that increasing C emissions from high latitude lakes will partly counteract the presumed increasing terrestrial C sink capacity at high latitudes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Disjunct populations of European vascular plant species keep the same climatic niches.\n \n \n \n \n\n\n \n Wasof, S.; Lenoir, J.; Aarrestad, P. A.; Alsos, I. G.; Armbruster, W. S.; Austrheim, G.; Bakkestuen, V.; Birks, H. J. B.; Bråthen, K. A.; Broennimann, O.; Brunet, J.; Bruun, H. H.; Dahlberg, C. J.; Diekmann, M.; Dullinger, S.; Dynesius, M.; Ejrnæs, R.; Gégout, J.; Graae, B. J.; Grytnes, J.; Guisan, A.; Hylander, K.; Jónsdóttir, I. S.; Kapfer, J.; Klanderud, K.; Luoto, M.; Milbau, A.; Moora, M.; Nygaard, B.; Odland, A.; Pauli, H.; Ravolainen, V.; Reinhardt, S.; Sandvik, S. M.; Schei, F. H.; Speed, J. D. M.; Svenning, J.; Thuiller, W.; Tveraabak, L. U.; Vandvik, V.; Velle, L. G.; Virtanen, R.; Vittoz, P.; Willner, W.; Wohlgemuth, T.; Zimmermann, N. E.; Zobel, M.; and Decocq, G.\n\n\n \n\n\n\n Global Ecology and Biogeography, 24(12): 1401–1412. December 2015.\n \n\n\n\n
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\n\n\n@article{wasof_disjunct_2015,\n\ttitle = {Disjunct populations of {European} vascular plant species keep the same climatic niches},\n\tvolume = {24},\n\tissn = {1466-8238},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/geb.12375/abstract},\n\tdoi = {10.1111/geb.12375},\n\tabstract = {Aim\n\nPrevious research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years.\n\n\nLocation\n\nEuropean Alps and Fennoscandia.\n\n\nMethods\n\nOf the studied pool of 888 terrestrial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distribution modelling to test for a region effect on each species' climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space.\n\n\nResults\n\nOnly one species (3\\%) of the 31 species with strictly disjunct populations and 58 species (16\\%) of the 358 species with distant populations showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic–alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps.\n\n\nMain conclusion\n\nClimatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000–15,000 years. Therefore, the basic assumption of species distribution models that a species' climatic niche is constant in space and time – at least on time scales 104 years or less – seems to be largely valid for arctic–alpine plants.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2016-11-08},\n\tjournal = {Global Ecology and Biogeography},\n\tauthor = {Wasof, Safaa and Lenoir, Jonathan and Aarrestad, Per Arild and Alsos, Inger Greve and Armbruster, W. Scott and Austrheim, Gunnar and Bakkestuen, Vegar and Birks, H. John B. and Bråthen, Kari Anne and Broennimann, Olivier and Brunet, Jörg and Bruun, Hans Henrik and Dahlberg, Carl Johan and Diekmann, Martin and Dullinger, Stefan and Dynesius, Mats and Ejrnæs, Rasmus and Gégout, Jean-Claude and Graae, Bente Jessen and Grytnes, John-Arvid and Guisan, Antoine and Hylander, Kristoffer and Jónsdóttir, Ingibjörg S. and Kapfer, Jutta and Klanderud, Kari and Luoto, Miska and Milbau, Ann and Moora, Mari and Nygaard, Bettina and Odland, Arvid and Pauli, Harald and Ravolainen, Virve and Reinhardt, Stefanie and Sandvik, Sylvi Marlen and Schei, Fride Høistad and Speed, James D. M. and Svenning, Jens-Christian and Thuiller, Wilfried and Tveraabak, Liv Unn and Vandvik, Vigdis and Velle, Liv Guri and Virtanen, Risto and Vittoz, Pascal and Willner, Wolfgang and Wohlgemuth, Thomas and Zimmermann, Niklaus E. and Zobel, Martin and Decocq, Guillaume},\n\tmonth = dec,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Alpine plants, Climatic Niche, arctic plants, disjunct distribution, distant populations, niche conservatism, niche optimum, niche overlap, niche width, species distribution modelling},\n\tpages = {1401--1412},\n}\n\n\n\n\n\n Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly invasive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestrial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distribution modelling to test for a region effect on each species' climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with strictly disjunct populations and 58 species (16%) of the 358 species with distant populations showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic–alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000–15,000 years. Therefore, the basic assumption of species distribution models that a species' climatic niche is constant in space and time – at least on time scales 104 years or less – seems to be largely valid for arctic–alpine plants.\n
\n\n\n\n \n\n \n \n \n \n \n \n Synchronous flowering despite differences in snowmelt timing among habitats of Empetrum hermaphroditum.\n \n \n \n \n\n\n \n Bienau, M. J.; Kröncke, M.; Eiserhardt, W. L.; Otte, A.; Graae, B. J.; Hagen, D.; Milbau, A.; Durka, W.; and Eckstein, R. L.\n\n\n \n\n\n\n Acta Oecologica, 69: 129–136. November 2015.\n \n\n\n\n
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\n\n\n@article{bienau_synchronous_2015,\n\ttitle = {Synchronous flowering despite differences in snowmelt timing among habitats of {Empetrum} hermaphroditum},\n\tvolume = {69},\n\tissn = {1146-609X},\n\turl = {http://www.sciencedirect.com/science/article/pii/S1146609X1530028X},\n\tdoi = {10.1016/j.actao.2015.10.005},\n\tabstract = {The topography within arctic-alpine landscapes is very heterogeneous, resulting in diverse snow distribution patterns, with different snowmelt timing in spring. This may influence the phenological development of arctic and alpine plant species and asynchronous flowering may promote adaptation of plants to their local environments.\n\nWe studied how flowering phenology of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitats (exposed ridges, sheltered depressions and birch forest) differing in winter snow depth and thus snowmelt timing in spring, and whether the observed patterns were consistent across three different study areas.\n\nDespite significant differences in snowmelt timing between habitats, full flowering of E. hermaphroditum was nearly synchronous between the habitats, and implies a high flowering overlap. Our data show that exposed ridges, which had a long lag phase between snowmelt and flowering, experienced different temperature and light conditions than the two late melting habitats between snowmelt and flowering.\n\nOur study demonstrates that small scale variation seems matter less to flowering of Empetrum than interannual differences in snowmelt timing.},\n\turldate = {2016-11-08},\n\tjournal = {Acta Oecologica},\n\tauthor = {Bienau, Miriam J. and Kröncke, Michael and Eiserhardt, Wolf L. and Otte, Annette and Graae, Bente J. and Hagen, Dagmar and Milbau, Ann and Durka, Walter and Eckstein, R. Lutz},\n\tmonth = nov,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Birch forest, Evergreen dwarf-shrub, sub-Arctic, tundra},\n\tpages = {129--136},\n}\n\n\n\n\n\n The topography within arctic-alpine landscapes is very heterogeneous, resulting in diverse snow distribution patterns, with different snowmelt timing in spring. This may influence the phenological development of arctic and alpine plant species and asynchronous flowering may promote adaptation of plants to their local environments. We studied how flowering phenology of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitats (exposed ridges, sheltered depressions and birch forest) differing in winter snow depth and thus snowmelt timing in spring, and whether the observed patterns were consistent across three different study areas. Despite significant differences in snowmelt timing between habitats, full flowering of E. hermaphroditum was nearly synchronous between the habitats, and implies a high flowering overlap. Our data show that exposed ridges, which had a long lag phase between snowmelt and flowering, experienced different temperature and light conditions than the two late melting habitats between snowmelt and flowering. Our study demonstrates that small scale variation seems matter less to flowering of Empetrum than interannual differences in snowmelt timing.\n
\n\n\n\n \n\n \n \n \n \n \n \n A global meta-analysis of the relative extent of intraspecific trait variation in plant communities.\n \n \n \n \n\n\n \n Siefert, A.; Violle, C.; Chalmandrier, L.; Albert, C. H.; Taudiere, A.; Fajardo, A.; Aarssen, L. W.; Baraloto, C.; Carlucci, M. B.; Cianciaruso, M. V.; de L. Dantas, V.; de Bello, F.; Duarte, L. D. S.; Fonseca, C. R.; Freschet, G. T.; Gaucherand, S.; Gross, N.; Hikosaka, K.; Jackson, B.; Jung, V.; Kamiyama, C.; Katabuchi, M.; Kembel, S. W.; Kichenin, E.; Kraft, N. J. B.; Lagerström, A.; Bagousse-Pinguet, Y. L.; Li, Y.; Mason, N.; Messier, J.; Nakashizuka, T.; Overton, J. M.; Peltzer, D. A.; Pérez-Ramos, I. M.; Pillar, V. D.; Prentice, H. C.; Richardson, S.; Sasaki, T.; Schamp, B. S.; Schöb, C.; Shipley, B.; Sundqvist, M.; Sykes, M. T.; Vandewalle, M.; and Wardle, D. A.\n\n\n \n\n\n\n Ecology Letters, 18(12): 1406–1419. December 2015.\n \n\n\n\n
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\n\n\n@article{siefert_global_2015,\n\ttitle = {A global meta-analysis of the relative extent of intraspecific trait variation in plant communities},\n\tvolume = {18},\n\tissn = {1461-0248},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/ele.12508/abstract},\n\tdoi = {10.1111/ele.12508},\n\tabstract = {Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25\\% of the total trait variation within communities and 32\\% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2017-02-10},\n\tjournal = {Ecology Letters},\n\tauthor = {Siefert, Andrew and Violle, Cyrille and Chalmandrier, Loïc and Albert, Cécile H. and Taudiere, Adrien and Fajardo, Alex and Aarssen, Lonnie W. and Baraloto, Christopher and Carlucci, Marcos B. and Cianciaruso, Marcus V. and de L. Dantas, Vinícius and de Bello, Francesco and Duarte, Leandro D. S. and Fonseca, Carlos R. and Freschet, Grégoire T. and Gaucherand, Stéphanie and Gross, Nicolas and Hikosaka, Kouki and Jackson, Benjamin and Jung, Vincent and Kamiyama, Chiho and Katabuchi, Masatoshi and Kembel, Steven W. and Kichenin, Emilie and Kraft, Nathan J. B. and Lagerström, Anna and Bagousse-Pinguet, Yoann Le and Li, Yuanzhi and Mason, Norman and Messier, Julie and Nakashizuka, Tohru and Overton, Jacob McC. and Peltzer, Duane A. and Pérez-Ramos, I. M. and Pillar, Valério D. and Prentice, Honor C. and Richardson, Sarah and Sasaki, Takehiro and Schamp, Brandon S. and Schöb, Christian and Shipley, Bill and Sundqvist, Maja and Sykes, Martin T. and Vandewalle, Marie and Wardle, David A.},\n\tmonth = dec,\n\tyear = {2015},\n\tkeywords = {\\#nosource, community ecology, functional diversity, interspecific variation, intraspecific variability, leaf trait, plant functional trait, trait-based ecology},\n\tpages = {1406--1419},\n}\n\n\n\n\n\n Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.\n
\n\n\n\n \n\n \n \n \n \n \n Sources of and processes controlling CO2 emissions change with the size of streams and rivers.\n \n \n \n\n\n \n Hotchkiss, E. R.; Hall, R. O.; Sponseller, R. A.; Butman, D.; Klaminder, J.; Laudon, H.; Rosvall, M.; and Karlsson, J.\n\n\n \n\n\n\n Nature Geoscience, 8(9): 696–+. September 2015.\n \n\n\n\n
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\n\n\n@article{hotchkiss_sources_2015,\n\ttitle = {Sources of and processes controlling {CO2} emissions change with the size of streams and rivers},\n\tvolume = {8},\n\tissn = {1752-0894},\n\tdoi = {10.1038/NGEO2507},\n\tabstract = {Carbon dioxide (CO2) evasion from streams and rivers to the atmosphere represents a substantial flux in the global carbon cycle(1-3). The proportions of CO2 emitted from streams and rivers that come from terrestrially derived CO2 or from CO2 produced within freshwater ecosystems through aquatic metabolism are not well quantified. Here we estimated CO2 emissions from running waters in the contiguous United States, based on freshwater chemical and physical characteristics and modelled gas transfer velocities at 1463 United States Geological Survey monitoring sites. We then assessed CO2 production from aquatic metabolism, compiled from previously published measurements of net ecosystem production from 187 streams and rivers across the contiguous United States. We find that CO2 produced by aquatic metabolism contributes about 28\\% of CO2 evasion from streams and rivers with flows between 0.0001 and 19,000 m(3) s(-1). We mathematically modelled CO2 flux from groundwater into running waters along a stream-river continuum to evaluate the relationship between stream size and CO2 source. Terrestrially derived CO2 dominates emissions from small streams, and the percentage of CO2 emissions from aquatic metabolism increases with stream size. We suggest that the relative role of rivers as conduits for terrestrial CO2 efflux and as reactors mineralizing terrestrial organic carbon is a function of their size and connectivity with landscapes.},\n\tlanguage = {English},\n\tnumber = {9},\n\tjournal = {Nature Geoscience},\n\tauthor = {Hotchkiss, E. R. and Hall, R. O. and Sponseller, R. A. and Butman, D. and Klaminder, J. and Laudon, H. and Rosvall, M. and Karlsson, J.},\n\tmonth = sep,\n\tyear = {2015},\n\tkeywords = {\\#nosource, aquatic ecosystems, budget, carbon-dioxide, cycle, inland waters, metabolism, temporal variability, united-states},\n\tpages = {696--+},\n}\n\n\n\n\n\n Carbon dioxide (CO2) evasion from streams and rivers to the atmosphere represents a substantial flux in the global carbon cycle(1-3). The proportions of CO2 emitted from streams and rivers that come from terrestrially derived CO2 or from CO2 produced within freshwater ecosystems through aquatic metabolism are not well quantified. Here we estimated CO2 emissions from running waters in the contiguous United States, based on freshwater chemical and physical characteristics and modelled gas transfer velocities at 1463 United States Geological Survey monitoring sites. We then assessed CO2 production from aquatic metabolism, compiled from previously published measurements of net ecosystem production from 187 streams and rivers across the contiguous United States. We find that CO2 produced by aquatic metabolism contributes about 28% of CO2 evasion from streams and rivers with flows between 0.0001 and 19,000 m(3) s(-1). We mathematically modelled CO2 flux from groundwater into running waters along a stream-river continuum to evaluate the relationship between stream size and CO2 source. Terrestrially derived CO2 dominates emissions from small streams, and the percentage of CO2 emissions from aquatic metabolism increases with stream size. We suggest that the relative role of rivers as conduits for terrestrial CO2 efflux and as reactors mineralizing terrestrial organic carbon is a function of their size and connectivity with landscapes.\n
\n\n\n\n \n\n \n \n \n \n \n Distinct impacts of different mammalian herbivore assemblages on arctic tundra CO2 exchange during the peak of the growing season.\n \n \n \n\n\n \n Metcalfe, D. B.; and Olofsson, J.\n\n\n \n\n\n\n Oikos, 124(12): 1632–1638. December 2015.\n \n\n\n\n
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\n\n\n@article{metcalfe_distinct_2015,\n\ttitle = {Distinct impacts of different mammalian herbivore assemblages on arctic tundra {CO2} exchange during the peak of the growing season},\n\tvolume = {124},\n\tissn = {0030-1299},\n\tdoi = {10.1111/oik.02085},\n\tabstract = {Herbivores play a key role in the carbon (C) cycle of arctic ecosystems, but these effects are currently poorly represented within models predicting land-atmosphere interactions under future climate change. Although some studies have examined the influence of various individual species of herbivores on tundra C sequestration, few studies have directly compared the effects of different herbivore assemblages. We measured peak growing season instantaneous ecosystem carbon dioxide (CO2) exchange (photosynthesis, respiration and net ecosystem exchange) on replicated plots in arctic tundra which, for 14 years, have excluded different portions of the herbivore population (grazed controls, large mammals excluded, both small and large mammals excluded). Herbivory suppressed photosynthetic CO2 uptake, but caused little change in ecosystem respiration. Despite evidence that small mammals consume a greater portion of plant biomass in these ecosystems, the effect of excluding only large herbivores was indistinguishable from that of excluding both large and small mammals. The herbivory-induced decline in photosynthesis was not entirely attributable to a decline in leaf area but also likely reflects shifts in plant community composition and/or species physiology. One shrub species - Betula nana - accounted for only around 13\\% of total aboveground vascular plant biomass but played a central role in controlling ecosystem CO2 uptake and release, and was suppressed by herbivory. We conclude that herbivores can have large effects on ecosystem C cycling due to shifts in plant aboveground biomass and community composition. An improved understanding of the mechanisms underlying the distinct ecosystem impacts of different herbivore groups will help to more accurately predict the net impacts of diverse herbivore communities on arctic C fluxes.},\n\tlanguage = {English},\n\tnumber = {12},\n\tjournal = {Oikos},\n\tauthor = {Metcalfe, Daniel B. and Olofsson, Johan},\n\tmonth = dec,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Decomposition, Soil, climate, communities, global change, responses, shrub expansion, species interactions, temperature, terrestrial ecosystems},\n\tpages = {1632--1638},\n}\n\n\n\n\n\n Herbivores play a key role in the carbon (C) cycle of arctic ecosystems, but these effects are currently poorly represented within models predicting land-atmosphere interactions under future climate change. Although some studies have examined the influence of various individual species of herbivores on tundra C sequestration, few studies have directly compared the effects of different herbivore assemblages. We measured peak growing season instantaneous ecosystem carbon dioxide (CO2) exchange (photosynthesis, respiration and net ecosystem exchange) on replicated plots in arctic tundra which, for 14 years, have excluded different portions of the herbivore population (grazed controls, large mammals excluded, both small and large mammals excluded). Herbivory suppressed photosynthetic CO2 uptake, but caused little change in ecosystem respiration. Despite evidence that small mammals consume a greater portion of plant biomass in these ecosystems, the effect of excluding only large herbivores was indistinguishable from that of excluding both large and small mammals. The herbivory-induced decline in photosynthesis was not entirely attributable to a decline in leaf area but also likely reflects shifts in plant community composition and/or species physiology. One shrub species - Betula nana - accounted for only around 13% of total aboveground vascular plant biomass but played a central role in controlling ecosystem CO2 uptake and release, and was suppressed by herbivory. We conclude that herbivores can have large effects on ecosystem C cycling due to shifts in plant aboveground biomass and community composition. An improved understanding of the mechanisms underlying the distinct ecosystem impacts of different herbivore groups will help to more accurately predict the net impacts of diverse herbivore communities on arctic C fluxes.\n
\n\n\n\n \n\n \n \n \n \n \n Plant growth response to direct and indirect temperature effects varies by vegetation type and elevation in a subarctic tundra.\n \n \n \n\n\n \n De Long, J. R.; Kardol, P.; Sundqvist, M. K.; Veen, G. F.; and Wardle, D. A.\n\n\n \n\n\n\n Oikos, 124(6): 772–783. June 2015.\n \n\n\n\n
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\n\n\n@article{de_long_plant_2015,\n\ttitle = {Plant growth response to direct and indirect temperature effects varies by vegetation type and elevation in a subarctic tundra},\n\tvolume = {124},\n\tissn = {0030-1299},\n\tdoi = {10.1111/oik.01764},\n\tabstract = {There has been growing recent use of elevational gradients as tools for assessing effects of temperature changes on vegetation properties, because these gradients enable temperature effects to be considered over larger spatial and temporal scales than is possible through conventional experiments. While many studies have explored the direct effects of temperature, the indirect effects of temperature through its long-term influence on soil abiotic or biotic properties remain essentially unexplored. We performed two climate chamber experiments using soils from a subarctic elevational gradient in Abisko, Sweden to investigate the direct effects of temperature, and indirect effects of temperature via soil legacies, on growth of two grass species. The soils were collected from each of two vegetation types (heath, dominated by dwarf shrubs, and meadow, dominated by graminoids and herbs) at each of three elevations. We found that plants responded to both the direct effect of temperature and its indirect effect via soil legacies, and that direct and indirect effects were largely decoupled. Vegetation type was a major determinant of plant responses to both the direct and indirect effects of temperature; responses to soils from increasing elevation were stronger and showed a more linear decline for meadow than for heath soils. The influence of soil biota on plant growth was independent of elevation, with a positive influence across all elevations regardless of soil origin for meadow soils but not for heath soils. Taken together, this means that responses of plant growth to soil legacy effects of temperature across the elevational gradient were driven primarily by soil abiotic, and not biotic, factors. These findings emphasize that vegetation type is a strong determinant of how temperature variation across elevational gradients impacts on plant growth, and highlight the need for considering both direct and indirect effects of temperature on plant responses to future climate change.},\n\tlanguage = {English},\n\tnumber = {6},\n\tjournal = {Oikos},\n\tauthor = {De Long, Jonathan R. and Kardol, Paul and Sundqvist, Maja K. and Veen, G. F. and Wardle, David A.},\n\tmonth = jun,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Global change, Nitrogen, altitudinal gradient, biomass, climate-change, community structure, diversity, forests, functional types, soil feedback},\n\tpages = {772--783},\n}\n\n\n\n\n\n There has been growing recent use of elevational gradients as tools for assessing effects of temperature changes on vegetation properties, because these gradients enable temperature effects to be considered over larger spatial and temporal scales than is possible through conventional experiments. While many studies have explored the direct effects of temperature, the indirect effects of temperature through its long-term influence on soil abiotic or biotic properties remain essentially unexplored. We performed two climate chamber experiments using soils from a subarctic elevational gradient in Abisko, Sweden to investigate the direct effects of temperature, and indirect effects of temperature via soil legacies, on growth of two grass species. The soils were collected from each of two vegetation types (heath, dominated by dwarf shrubs, and meadow, dominated by graminoids and herbs) at each of three elevations. We found that plants responded to both the direct effect of temperature and its indirect effect via soil legacies, and that direct and indirect effects were largely decoupled. Vegetation type was a major determinant of plant responses to both the direct and indirect effects of temperature; responses to soils from increasing elevation were stronger and showed a more linear decline for meadow than for heath soils. The influence of soil biota on plant growth was independent of elevation, with a positive influence across all elevations regardless of soil origin for meadow soils but not for heath soils. Taken together, this means that responses of plant growth to soil legacy effects of temperature across the elevational gradient were driven primarily by soil abiotic, and not biotic, factors. These findings emphasize that vegetation type is a strong determinant of how temperature variation across elevational gradients impacts on plant growth, and highlight the need for considering both direct and indirect effects of temperature on plant responses to future climate change.\n
\n\n\n\n \n\n \n \n \n \n \n Microbial mediation of complex subterranean mineral structures.\n \n \n \n\n\n \n Tisato, N.; Torriani, S. F. F.; Monteux, S.; Sauro, F.; De Waele, J.; Tavagna, M. L.; D'Angeli, I. M.; Chailloux, D.; Renda, M.; Eglinton, T. I.; and Bontognali, T. R. R.\n\n\n \n\n\n\n Scientific Reports, 5: 15525. October 2015.\n 00003\n\n\n\n
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\n\n\n@article{tisato_microbial_2015,\n\ttitle = {Microbial mediation of complex subterranean mineral structures},\n\tvolume = {5},\n\tissn = {2045-2322},\n\tdoi = {10.1038/srep15525},\n\tabstract = {Helictites-an enigmatic type of mineral structure occurring in some caves-differ from classical speleothems as they develop with orientations that defy gravity. While theories for helictite formation have been forwarded, their genesis remains equivocal. Here, we show that a remarkable suite of helictites occurring in Asperge Cave (France) are formed by biologically-mediated processes, rather than abiotic processes as had hitherto been proposed. Morphological and petro-physical properties are inconsistent with mineral precipitation under purely physico-chemical control. Instead, microanalysis and molecular-biological investigation reveals the presence of a prokaryotic biofilm intimately associated with the mineral structures. We propose that microbially-influenced mineralization proceeds within a gliding biofilm which serves as a nucleation site for CaCO3, and where chemotaxis influences the trajectory of mineral growth, determining the macroscopic morphology of the speleothems. The influence of biofilms may explain the occurrence of similar speleothems in other caves worldwide, and sheds light on novel biomineralization processes.},\n\tlanguage = {English},\n\tjournal = {Scientific Reports},\n\tauthor = {Tisato, Nicola and Torriani, Stefano F. F. and Monteux, Sylvain and Sauro, Francesco and De Waele, Jo and Tavagna, Maria Luisa and D'Angeli, Ilenia M. and Chailloux, Daniel and Renda, Michel and Eglinton, Timothy I. and Bontognali, Tomaso R. R.},\n\tmonth = oct,\n\tyear = {2015},\n\tnote = {00003},\n\tkeywords = {\\#nosource, biomineralization, carbonate, cave, life, mars, myxococcus-xanthus, search},\n\tpages = {15525},\n}\n\n\n\n\n\n Helictites-an enigmatic type of mineral structure occurring in some caves-differ from classical speleothems as they develop with orientations that defy gravity. While theories for helictite formation have been forwarded, their genesis remains equivocal. Here, we show that a remarkable suite of helictites occurring in Asperge Cave (France) are formed by biologically-mediated processes, rather than abiotic processes as had hitherto been proposed. Morphological and petro-physical properties are inconsistent with mineral precipitation under purely physico-chemical control. Instead, microanalysis and molecular-biological investigation reveals the presence of a prokaryotic biofilm intimately associated with the mineral structures. We propose that microbially-influenced mineralization proceeds within a gliding biofilm which serves as a nucleation site for CaCO3, and where chemotaxis influences the trajectory of mineral growth, determining the macroscopic morphology of the speleothems. The influence of biofilms may explain the occurrence of similar speleothems in other caves worldwide, and sheds light on novel biomineralization processes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Comparative study on bacterial carbon sources in lake sediments: the role of methanotrophy.\n \n \n \n \n\n\n \n Steger, K.; Premke, K.; Gudasz, C.; Boschker, H. T. S.; and Tranvik, L. J.\n\n\n \n\n\n\n Aquatic Microbial Ecology, 76(1): 39–47. August 2015.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{steger_comparative_2015,\n\ttitle = {Comparative study on bacterial carbon sources in lake sediments: the role of methanotrophy},\n\tvolume = {76},\n\tissn = {0948-3055, 1616-1564},\n\tshorttitle = {Comparative study on bacterial carbon sources in lake sediments},\n\turl = {https://www.int-res.com/abstracts/ame/v76/n1/p39-47/},\n\tdoi = {10.3354/ame01766},\n\tabstract = {Methane-derived carbon can be important in both benthic and pelagic food webs. Either generated in the anaerobic layers of the sediment or in the anaerobic hypolimnion of stratified eutrophic lakes, methane is an excellent carbon source for aerobic methanotrophic bacteria. The very negative methane δ13C-signal in the methanotrophic biomass provides an excellent opportunity to trace the use of methane-derived carbon in food webs. We studied carbon sources of benthic bacteria in a range of Swedish lakes with different inputs of terrestrial organic carbon and indigenous primary production. We analyzed the 13C:12C ratios in phospholipid-derived fatty acids, which serve as biomarkers for specific groups of Bacteria. We demonstrate that methane is an important carbon source for sediment bacteria, not only for the methanotrophic community but also for the non-methanotrophic heterotrophic bacteria. This most likely indirect utilization of isotopically highly depleted methane masks the stable isotope signatures for terrestrial input and local primary production in the heterotrophic bacterial community.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-08-31},\n\tjournal = {Aquatic Microbial Ecology},\n\tauthor = {Steger, K. and Premke, K. and Gudasz, C. and Boschker, H. T. S. and Tranvik, L. J.},\n\tmonth = aug,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Benthic microbes, Boreal lakes, Methanotrophic bacteria, PLFA, Phospholipid-derived fatty acid, Stable isotopes},\n\tpages = {39--47},\n}\n\n\n\n\n\n Methane-derived carbon can be important in both benthic and pelagic food webs. Either generated in the anaerobic layers of the sediment or in the anaerobic hypolimnion of stratified eutrophic lakes, methane is an excellent carbon source for aerobic methanotrophic bacteria. The very negative methane δ13C-signal in the methanotrophic biomass provides an excellent opportunity to trace the use of methane-derived carbon in food webs. We studied carbon sources of benthic bacteria in a range of Swedish lakes with different inputs of terrestrial organic carbon and indigenous primary production. We analyzed the 13C:12C ratios in phospholipid-derived fatty acids, which serve as biomarkers for specific groups of Bacteria. We demonstrate that methane is an important carbon source for sediment bacteria, not only for the methanotrophic community but also for the non-methanotrophic heterotrophic bacteria. This most likely indirect utilization of isotopically highly depleted methane masks the stable isotope signatures for terrestrial input and local primary production in the heterotrophic bacterial community.\n
\n\n\n\n \n\n \n \n \n \n \n \n Temperature sensitivity of organic carbon mineralization in contrasting lake sediments.\n \n \n \n \n\n\n \n Gudasz, C.; Sobek, S.; Bastviken, D.; Koehler, B.; and Tranvik, L. J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 120(7): 1215–1225. 2015.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2015JG002928\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{gudasz_temperature_2015,\n\ttitle = {Temperature sensitivity of organic carbon mineralization in contrasting lake sediments},\n\tvolume = {120},\n\tcopyright = {©2015. The Authors.},\n\tissn = {2169-8961},\n\turl = {http://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2015JG002928},\n\tdoi = {10.1002/2015JG002928},\n\tabstract = {Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contributions of allochthonous and autochthonous components, however, showed similar temperature sensitivity in short-term incubation experiments. Whether the mineralization of OC in lake sediments dominated by allochthonous or autochthonous OC has different temperature sensitivity in the longer term has not been addressed. We incubated sediments from two boreal lakes that had contrasting OC origin (allochthonous versus autochthonous), and OC characteristics (C/N ratios of 21 and 10) at 1, 3, 5, 8, 13, and 21°C for five months. Compared to soil and litter mineralization, sediment OC mineralization rates were low in spite of low apparent activation energy (Ea). The fraction of the total OC pool that was lost during five months varied between 0.4 and 14.8\\%. We estimate that the sediment OC pool not becoming long-term preserved was degraded with average apparent turnover times between 3 and 32 years. While OC mineralization was strongly dependent on temperature as well as on OC composition and origin, temperature sensitivity was similar across lakes and over time. We suggest that the temperature sensitivity of OC mineralization in lake sediments is similar across systems within the relevant seasonal scales of OC supply and degradation.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2020-08-31},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Gudasz, Cristian and Sobek, Sebastian and Bastviken, David and Koehler, Birgit and Tranvik, Lars J.},\n\tyear = {2015},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/2015JG002928},\n\tkeywords = {\\#nosource, lake sediment, mineralization, organic carbon, temperature sensitivity, turnover time},\n\tpages = {1215--1225},\n}\n\n\n\n\n\n Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contributions of allochthonous and autochthonous components, however, showed similar temperature sensitivity in short-term incubation experiments. Whether the mineralization of OC in lake sediments dominated by allochthonous or autochthonous OC has different temperature sensitivity in the longer term has not been addressed. We incubated sediments from two boreal lakes that had contrasting OC origin (allochthonous versus autochthonous), and OC characteristics (C/N ratios of 21 and 10) at 1, 3, 5, 8, 13, and 21°C for five months. Compared to soil and litter mineralization, sediment OC mineralization rates were low in spite of low apparent activation energy (Ea). The fraction of the total OC pool that was lost during five months varied between 0.4 and 14.8%. We estimate that the sediment OC pool not becoming long-term preserved was degraded with average apparent turnover times between 3 and 32 years. While OC mineralization was strongly dependent on temperature as well as on OC composition and origin, temperature sensitivity was similar across lakes and over time. We suggest that the temperature sensitivity of OC mineralization in lake sediments is similar across systems within the relevant seasonal scales of OC supply and degradation.\n
\n\n\n\n \n\n \n \n \n \n \n \n Intraspecific autochthonous and allochthonous resource use by zooplankton in a humic lake during the transitions between winter, summer and fall.\n \n \n \n \n\n\n \n Berggren, M.; Bergström, A.; and Karlsson, J.\n\n\n \n\n\n\n PLoS ONE, 10(3): e0120575. March 2015.\n 00016\n\n\n\n
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\n\n\n@article{berggren_intraspecific_2015,\n\ttitle = {Intraspecific autochthonous and allochthonous resource use by zooplankton in a humic lake during the transitions between winter, summer and fall},\n\tvolume = {10},\n\turl = {http://dx.doi.org/10.1371/journal.pone.0120575},\n\tdoi = {10.1371/journal.pone.0120575},\n\tabstract = {Seasonal patterns in assimilation of externally produced, allochthonous, organic matter into aquatic food webs are poorly understood, especially in brown-water lakes. We studied the allochthony (share biomass of terrestrial origin) in cladoceran, calanoid and cyclopoid micro-crustacean zooplankton from late winter to fall during two years in a small humic lake (Sweden). The use of allochthonous resources was important for sustaining a small population of calanoids in the water column during late winter. However, in summer the calanoids shifted to 100\\% herbivory, increasing their biomass several-fold by making efficient use of the pelagic primary production. In contrast, the cyclopoids and cladocerans remained at high levels of allochthony throughout the seasons, both groups showing the mean allochthony of 0.56 (range in mean 0.17-0.79 and 0.34-0.75, for the respective group, depending on model parameters). Our study shows that terrestrial organic matter can be an important resource for cyclopoids and cladocerans on an annual basis, forming a significant link between terrestrial organic matter and the higher trophic levels of the food web, but it can also be important for sustaining otherwise herbivorous calanoids during periods of low primary production in late winter.},\n\tnumber = {3},\n\turldate = {2015-03-20},\n\tjournal = {PLoS ONE},\n\tauthor = {Berggren, Martin and Bergström, Ann-Kristin and Karlsson, Jan},\n\tmonth = mar,\n\tyear = {2015},\n\tnote = {00016},\n\tkeywords = {\\#nosource},\n\tpages = {e0120575},\n}\n\n\n\n\n\n Seasonal patterns in assimilation of externally produced, allochthonous, organic matter into aquatic food webs are poorly understood, especially in brown-water lakes. We studied the allochthony (share biomass of terrestrial origin) in cladoceran, calanoid and cyclopoid micro-crustacean zooplankton from late winter to fall during two years in a small humic lake (Sweden). The use of allochthonous resources was important for sustaining a small population of calanoids in the water column during late winter. However, in summer the calanoids shifted to 100% herbivory, increasing their biomass several-fold by making efficient use of the pelagic primary production. In contrast, the cyclopoids and cladocerans remained at high levels of allochthony throughout the seasons, both groups showing the mean allochthony of 0.56 (range in mean 0.17-0.79 and 0.34-0.75, for the respective group, depending on model parameters). Our study shows that terrestrial organic matter can be an important resource for cyclopoids and cladocerans on an annual basis, forming a significant link between terrestrial organic matter and the higher trophic levels of the food web, but it can also be important for sustaining otherwise herbivorous calanoids during periods of low primary production in late winter.\n
\n\n\n\n \n\n \n \n \n \n \n \n Strong responses of subarctic plant communities to long-term reindeer feces manipulation.\n \n \n \n \n\n\n \n Barthelemy, H.; Stark, S.; and Olofsson, J.\n\n\n \n\n\n\n Ecosystems, 18(5): 740–751. August 2015.\n \n\n\n\n
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\n\n\n@article{barthelemy_strong_2015,\n\ttitle = {Strong responses of subarctic plant communities to long-term reindeer feces manipulation},\n\tvolume = {18},\n\tissn = {1432-9840, 1435-0629},\n\turl = {http://link.springer.com/article/10.1007/s10021-015-9856-y},\n\tdoi = {10.1007/s10021-015-9856-y},\n\tabstract = {Deposition of feces is a key mechanism by which herbivores influence soil nutrient cycling and plant production, but the knowledge about its importance for plant production and community structure is still rudimental since experimental evidence is scarce. We thus performed a 7-year long reindeer feces manipulation experiment in two tundra vegetation types with contrasting nutrient availability and analyzed effects on plant community composition and soil nutrient availability. Despite feces being fairly nutrient poor, feces manipulation had strong effect on both the nutrient-poor heath and the nutrient-rich meadow. The strongest effect was detected when feces were added at high density, with a substantial increase in total vascular plant productivity and graminoids in the two communities. Doubling natural deposition of reindeer feces enhanced primary production and the growth of deciduous shrubs in the heath. By contrast, removal of feces decreased only the production of graminoids and deciduous shrubs in the heath. Although the response to feces addition was faster in the nutrient-rich meadow, after 7 years it was more pronounced in the nutrient-poor heath. The effect of feces manipulation on soil nutrient availability was low and temporarily variable. Our study provides experimental evidence for a central role of herbivore feces in regulating primary production when herbivores are abundant enough. Deposition of feces alone does, however, not cause dramatic vegetation shifts; to drive unproductive heath to a productive grass dominated state, herbivore trampling, and grazing are probably also needed.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-07},\n\tjournal = {Ecosystems},\n\tauthor = {Barthelemy, Hélène and Stark, Sari and Olofsson, Johan},\n\tmonth = aug,\n\tyear = {2015},\n\tkeywords = {\\#nosource, Environmental Management, Geoecology/Natural Processes, Hydrology/Water Resources, Plant Sciences, Zoology, alpine meadow, ecology, feces fertilization, forage quality, microbial immobilization, plant productivity, plant-herbivore interactions, reindeer grazing, soil nutrient availability, tundra heath},\n\tpages = {740--751},\n}\n\n\n\n\n\n Deposition of feces is a key mechanism by which herbivores influence soil nutrient cycling and plant production, but the knowledge about its importance for plant production and community structure is still rudimental since experimental evidence is scarce. We thus performed a 7-year long reindeer feces manipulation experiment in two tundra vegetation types with contrasting nutrient availability and analyzed effects on plant community composition and soil nutrient availability. Despite feces being fairly nutrient poor, feces manipulation had strong effect on both the nutrient-poor heath and the nutrient-rich meadow. The strongest effect was detected when feces were added at high density, with a substantial increase in total vascular plant productivity and graminoids in the two communities. Doubling natural deposition of reindeer feces enhanced primary production and the growth of deciduous shrubs in the heath. By contrast, removal of feces decreased only the production of graminoids and deciduous shrubs in the heath. Although the response to feces addition was faster in the nutrient-rich meadow, after 7 years it was more pronounced in the nutrient-poor heath. The effect of feces manipulation on soil nutrient availability was low and temporarily variable. Our study provides experimental evidence for a central role of herbivore feces in regulating primary production when herbivores are abundant enough. Deposition of feces alone does, however, not cause dramatic vegetation shifts; to drive unproductive heath to a productive grass dominated state, herbivore trampling, and grazing are probably also needed.\n
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\n \n \n\n \n \n \n \n \n \n Evergreen shrubs dominate responses to experimental summer warming and fertilization in Canadian mesic low arctic tundra.\n \n \n \n \n\n\n \n Zamin, T. J.; Bret‐Harte, M. S.; and Grogan, P.\n\n\n \n\n\n\n Journal of Ecology, 102(3): 749–766. May 2014.\n \n\n\n\n
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\n\n\n@article{zamin_evergreen_2014,\n\ttitle = {Evergreen shrubs dominate responses to experimental summer warming and fertilization in {Canadian} mesic low arctic tundra},\n\tvolume = {102},\n\tcopyright = {http://onlinelibrary.wiley.com/termsAndConditions\\#vor},\n\tissn = {0022-0477, 1365-2745},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2745.12237},\n\tdoi = {10.1111/1365-2745.12237},\n\tabstract = {Summary\n \n \n \n Climate change in arctic tundra is projected to increase soil fertility, which may alter plant community composition and ecosystem processes by shifting niche space to favour particular species' life‐history strategies. The rate and magnitude of change in soil fertility may be critical to determining plant community responses, and so effects of slow increases in nutrient availability due to climate warming may differ substantially from those of chronic high‐level fertilizer additions.\n \n \n We investigated above‐ and below‐ground plant biomass responses to experimental summer warming and above‐ground responses to nutrient additions (low‐level N and factorial N and P) in a mesic birch hummock tundra community in the central Canadian Low Arctic after eight years of experimental treatment.\n \n \n \n Plant community biomass responses to experimental warming were fundamentally different from those of high‐level N and/or P additions, mainly due to opposing effects on the evergreen shrubs. Evergreen shrub above‐ground biomass increased 66\\% with greenhouse warming, but decreased on average 70\\% with high‐level N and/or P additions, driven by the strong responses of\n Rhododendron subarcticum\n . Because of this evergreen response, greenhouse‐warming increased total above‐ground biomass by 32\\% and total below‐ground biomass by 70\\%, but did not significantly change the total above‐ground/below‐ground biomass ratio. However, warming increased the shoot/root ratio of\n Betula glandulosa\n threefold.\n \n \n \n Increased soil fertility created interactions between N and P availability, whereby increased P availability led to a substantial increase in inorganic N availability. Meanwhile, the growth of several species that span a range of different functional groups was stimulated by the separate N and P additions. These factorial fertilization results highlight the importance of understanding climate warming impacts on availability of both of these nutrients in order to predict plant community responses.\n \n \n \n Synthesis\n . Our results strongly suggest that the trajectory of mesic tundra vegetation change with warming depends critically on the rate of increase in soil fertility. The relatively large greenhouse‐induced biomass increase in evergreen compared to deciduous shrubs suggests that carbon balance and albedo feedbacks to warming will be restricted in mesic tundra ecosystems, at least in their early responses to climate change.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2024-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {Zamin, Tara J. and Bret‐Harte, M. Syndonia and Grogan, Paul},\n\teditor = {Aerts, Rien},\n\tmonth = may,\n\tyear = {2014},\n\tkeywords = {\\#nosource, Nitrogen, Soil fertility, climate change, determinants of plant community diversity and structure, greenhouses, life history strategy, life-history strategy, nitrogen, nutrient addition, phosphorus, shrub growth, soil fertility, tundra vegetation},\n\tpages = {749--766},\n}\n\n\n\n\n\n Summary Climate change in arctic tundra is projected to increase soil fertility, which may alter plant community composition and ecosystem processes by shifting niche space to favour particular species' life‐history strategies. The rate and magnitude of change in soil fertility may be critical to determining plant community responses, and so effects of slow increases in nutrient availability due to climate warming may differ substantially from those of chronic high‐level fertilizer additions. We investigated above‐ and below‐ground plant biomass responses to experimental summer warming and above‐ground responses to nutrient additions (low‐level N and factorial N and P) in a mesic birch hummock tundra community in the central Canadian Low Arctic after eight years of experimental treatment. Plant community biomass responses to experimental warming were fundamentally different from those of high‐level N and/or P additions, mainly due to opposing effects on the evergreen shrubs. Evergreen shrub above‐ground biomass increased 66% with greenhouse warming, but decreased on average 70% with high‐level N and/or P additions, driven by the strong responses of Rhododendron subarcticum . Because of this evergreen response, greenhouse‐warming increased total above‐ground biomass by 32% and total below‐ground biomass by 70%, but did not significantly change the total above‐ground/below‐ground biomass ratio. However, warming increased the shoot/root ratio of Betula glandulosa threefold. Increased soil fertility created interactions between N and P availability, whereby increased P availability led to a substantial increase in inorganic N availability. Meanwhile, the growth of several species that span a range of different functional groups was stimulated by the separate N and P additions. These factorial fertilization results highlight the importance of understanding climate warming impacts on availability of both of these nutrients in order to predict plant community responses. Synthesis . Our results strongly suggest that the trajectory of mesic tundra vegetation change with warming depends critically on the rate of increase in soil fertility. The relatively large greenhouse‐induced biomass increase in evergreen compared to deciduous shrubs suggests that carbon balance and albedo feedbacks to warming will be restricted in mesic tundra ecosystems, at least in their early responses to climate change.\n
\n\n\n\n \n\n \n \n \n \n \n \n Tips for the next phase of winter climate-change study in plant–soil systems.\n \n \n \n \n\n\n \n Makoto, K.\n\n\n \n\n\n\n Ecological Research, 29(4): 511–515. July 2014.\n \n\n\n\n
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\n\n\n\n@article{makoto_tips_2014,\n\ttitle = {Tips for the next phase of winter climate-change study in plant–soil systems},\n\tvolume = {29},\n\tissn = {1440-1703},\n\turl = {https://doi.org/10.1007/s11284-014-1171-0},\n\tdoi = {10.1007/s11284-014-1171-0},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Ecological Research},\n\tauthor = {Makoto, Kobayashi},\n\tmonth = jul,\n\tyear = {2014},\n\tkeywords = {\\#nosource, Behavioural Sciences, Forestry, Plant Sciences, Zoology, ecology, evolutionary biology},\n\tpages = {511--515},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Winter climate change, plant traits and nutrient and carbon cycling in cold biomes.\n \n \n \n \n\n\n \n Cornelissen, J. H. C.; and Makoto, K.\n\n\n \n\n\n\n Ecological Research, 29(4): 517–527. 2014.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1007/s11284-013-1106-1\n\n\n\n
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\n\n\n@article{cornelissen_winter_2014,\n\ttitle = {Winter climate change, plant traits and nutrient and carbon cycling in cold biomes},\n\tvolume = {29},\n\tcopyright = {© 2014 The Ecological Society of Japan},\n\tissn = {1440-1703},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1007/s11284-013-1106-1},\n\tdoi = {10.1007/s11284-013-1106-1},\n\tabstract = {It is essential that scientists be able to predict how strong climate warming, including profound changes to winter climate, will affect the ecosystem services of alpine, arctic and boreal areas, and how these services are driven by vegetation–soil feedbacks. One fruitful avenue for studying such changing feedbacks is through plant functional traits, as an understanding of these traits may help us to understand and synthesise (1) responses of vegetation (through ‘response traits’ and ‘specific response functions’ of each species) to winter climate and (2) the effects of changing vegetation composition (through ‘effect traits’ and ‘specific effect functions’ of each species) on soil functions. It is the relative correspondence of variation in response and effect traits that will provide useful data on the impacts of winter climate change on carbon and nutrient cycling processes. Here we discuss several examples of how the trait-based, response–effect framework can help scientists to better understand the effects of winter warming on key ecosystem functions in cold biomes. These examples support the view that measuring species for their response and effect traits, and how these traits are linked across species through correspondence of variation in specific response and effects functions, may be a useful approach for teasing out the contribution of changing vegetation composition to winter warming effects on ecosystem functions. This approach will be particularly useful when linked with ecosystem-level measurements of vegetation and process responses to winter warming along natural gradients, over medium time scales in given sites or in response to experimental climate manipulations.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2024-03-27},\n\tjournal = {Ecological Research},\n\tauthor = {Cornelissen, Johannes H. C. and Makoto, Kobayashi},\n\tyear = {2014},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1007/s11284-013-1106-1},\n\tkeywords = {\\#nosource, Alpine, Arctic, Behavioural Sciences, Biogeochemistry, Boreal, Forestry, Plant Sciences, Plant functional traits, Response–effect framework, Snow roots, Species ecosystem impact, Winter climate warming, Zoology, alpine, boreal, ecology, evolutionary biology},\n\tpages = {517--527},\n}\n\n\n\n\n\n It is essential that scientists be able to predict how strong climate warming, including profound changes to winter climate, will affect the ecosystem services of alpine, arctic and boreal areas, and how these services are driven by vegetation–soil feedbacks. One fruitful avenue for studying such changing feedbacks is through plant functional traits, as an understanding of these traits may help us to understand and synthesise (1) responses of vegetation (through ‘response traits’ and ‘specific response functions’ of each species) to winter climate and (2) the effects of changing vegetation composition (through ‘effect traits’ and ‘specific effect functions’ of each species) on soil functions. It is the relative correspondence of variation in response and effect traits that will provide useful data on the impacts of winter climate change on carbon and nutrient cycling processes. Here we discuss several examples of how the trait-based, response–effect framework can help scientists to better understand the effects of winter warming on key ecosystem functions in cold biomes. These examples support the view that measuring species for their response and effect traits, and how these traits are linked across species through correspondence of variation in specific response and effects functions, may be a useful approach for teasing out the contribution of changing vegetation composition to winter warming effects on ecosystem functions. This approach will be particularly useful when linked with ecosystem-level measurements of vegetation and process responses to winter warming along natural gradients, over medium time scales in given sites or in response to experimental climate manipulations.\n
\n\n\n\n \n\n \n \n \n \n \n Attempted predation of Northern Hawk-owl Surnia ullula by Common Kestrel Falco tinnunculus?.\n \n \n \n\n\n \n Larson, K. W.; and Kundisch, S.\n\n\n \n\n\n\n Ornis Svecica, 24(3-4): 164–165. 2014.\n 00000\n\n\n\n
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\n\n\n\n@article{larson_attempted_2014,\n\ttitle = {Attempted predation of {Northern} {Hawk}-owl {Surnia} ullula by {Common} {Kestrel} {Falco} tinnunculus?},\n\tvolume = {24},\n\tissn = {1102-6812},\n\tnumber = {3-4},\n\tjournal = {Ornis Svecica},\n\tauthor = {Larson, Keith W. and Kundisch, Sieglinde},\n\tyear = {2014},\n\tnote = {00000},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {164--165},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n The role of inland waters in the carbon cycle at high latitudes.\n \n \n \n \n\n\n \n Lundin, E.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2014.\n Publisher: Umeå universitet\n\n\n\n
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\n\n\n@phdthesis{lundin_role_2014,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {The role of inland waters in the carbon cycle at high latitudes},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-84541},\n\tabstract = {Understanding the drivers of climate change requires knowledge about the global carbon (C) cycle. Although inland waters play an important role in the C cycle by emitting and burying C, streams and ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Lundin, Erik},\n\tcollaborator = {Karlsson, Jan and Giesler, Reiner},\n\tyear = {2014},\n\tnote = {Publisher: Umeå universitet},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n Understanding the drivers of climate change requires knowledge about the global carbon (C) cycle. Although inland waters play an important role in the C cycle by emitting and burying C, streams and ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of seabird nitrogen input on biomass and carbon accumulation after 50 years of primary succession on a young volcanic island, Surtsey.\n \n \n \n \n\n\n \n Leblans, N. I. W.; Sigurdsson, B. D.; Roefs, P.; Thuys, R.; Magnússon, B.; and Janssens, I. A.\n\n\n \n\n\n\n Biogeosciences, 11(22): 6237–6250. November 2014.\n \n\n\n\n
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\n\n\n@article{leblans_effects_2014,\n\ttitle = {Effects of seabird nitrogen input on biomass and carbon accumulation after 50 years of primary succession on a young volcanic island, {Surtsey}},\n\tvolume = {11},\n\tissn = {1726-4170},\n\turl = {https://www.biogeosciences.net/11/6237/2014/},\n\tdoi = {10.5194/bg-11-6237-2014},\n\tabstract = {{\\textless}p{\\textgreater}{\\textless}strong{\\textgreater}Abstract.{\\textless}/strong{\\textgreater} What happens during primary succession after the first colonizers have occupied a pristine surface largely depends on how they ameliorate living conditions for other species. For vascular plants the onset of soil development and associated increase in nutrient (mainly nitrogen; N) and water availability is especially important. Here, we report the relationship between N accumulation and biomass and ecosystem carbon (C) stocks in a 50-year-old volcanic island, Surtsey, Iceland, where N stocks are still exceptionally low. However, a 28-year-old seagull colony on the island provided nutrient-enriched areas, which enabled us to assess the relationship between N stock and biomass and ecosystem C stocks across a much larger range in N stock. Further, we compared areas on shallow and deep tephra sands as we expected that deep-rooted systems would be more efficient in retaining N. The sparsely vegetated area outside the colony had accumulated 0.7 kg N ha$^{\\textrm{−1}}$ yr$^{\\textrm{−1}}$, which was ca. 50–60\\% of the estimated N input rate from wet deposition. This approximates values for systems under low N input and bare dune habitats. The seagulls have added, on average, 47 kg N ha$^{\\textrm{−1}}$ yr$^{\\textrm{−1}}$, which induced a shift from belowground to aboveground in ecosystem N and C stocks and doubled the ecosystem N-use efficiency, determined as the ratio of biomass and C storage per unit N input. Soil depth did not significantly affect total N stocks, which suggests a high N retention potential. Both total ecosystem biomass and C stocks were strongly correlated with N stock inside the colony, which indicated the important role of N during the first steps of primary succession. Inside the colony, the ecosystem biomass C stocks (17–27 ton C ha$^{\\textrm{−1}}$) had reached normal values for grasslands, while the soil organic carbon (SOC) stocks (4–10 ton C ha$^{\\textrm{−1}}$ were only a fraction of normal grassland values. Thus, it will take a long time until the SOC stock reaches equilibrium with the current primary production, during which conditions for new colonists may change.{\\textless}/p{\\textgreater}},\n\tlanguage = {English},\n\tnumber = {22},\n\turldate = {2019-05-20},\n\tjournal = {Biogeosciences},\n\tauthor = {Leblans, N. I. W. and Sigurdsson, B. D. and Roefs, P. and Thuys, R. and Magnússon, B. and Janssens, I. A.},\n\tmonth = nov,\n\tyear = {2014},\n\tkeywords = {\\#nosource},\n\tpages = {6237--6250},\n}\n\n\n\n\n\n \\textlessp\\textgreater\\textlessstrong\\textgreaterAbstract.\\textless/strong\\textgreater What happens during primary succession after the first colonizers have occupied a pristine surface largely depends on how they ameliorate living conditions for other species. For vascular plants the onset of soil development and associated increase in nutrient (mainly nitrogen; N) and water availability is especially important. Here, we report the relationship between N accumulation and biomass and ecosystem carbon (C) stocks in a 50-year-old volcanic island, Surtsey, Iceland, where N stocks are still exceptionally low. However, a 28-year-old seagull colony on the island provided nutrient-enriched areas, which enabled us to assess the relationship between N stock and biomass and ecosystem C stocks across a much larger range in N stock. Further, we compared areas on shallow and deep tephra sands as we expected that deep-rooted systems would be more efficient in retaining N. The sparsely vegetated area outside the colony had accumulated 0.7 kg N ha$^{\\textrm{−1}}$ yr$^{\\textrm{−1}}$, which was ca. 50–60% of the estimated N input rate from wet deposition. This approximates values for systems under low N input and bare dune habitats. The seagulls have added, on average, 47 kg N ha$^{\\textrm{−1}}$ yr$^{\\textrm{−1}}$, which induced a shift from belowground to aboveground in ecosystem N and C stocks and doubled the ecosystem N-use efficiency, determined as the ratio of biomass and C storage per unit N input. Soil depth did not significantly affect total N stocks, which suggests a high N retention potential. Both total ecosystem biomass and C stocks were strongly correlated with N stock inside the colony, which indicated the important role of N during the first steps of primary succession. Inside the colony, the ecosystem biomass C stocks (17–27 ton C ha$^{\\textrm{−1}}$) had reached normal values for grasslands, while the soil organic carbon (SOC) stocks (4–10 ton C ha$^{\\textrm{−1}}$ were only a fraction of normal grassland values. Thus, it will take a long time until the SOC stock reaches equilibrium with the current primary production, during which conditions for new colonists may change.\\textless/p\\textgreater\n
\n\n\n\n \n\n \n \n \n \n \n \n Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities.\n \n \n \n \n\n\n \n Leeuwen, C. H. A. v.; Sarneel, J. M.; Paassen, J. v.; Rip, W. J.; and Bakker, E. S.\n\n\n \n\n\n\n Journal of Ecology, 102(4): 998–1007. 2014.\n \n\n\n\n
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\n\n\n@article{leeuwen_hydrology_2014,\n\ttitle = {Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities},\n\tvolume = {102},\n\tcopyright = {© 2014 The Authors. Journal of Ecology © 2014 British Ecological Society},\n\tissn = {1365-2745},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.12250},\n\tdoi = {10.1111/1365-2745.12250},\n\tabstract = {Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination, and how these interactions determine plant community assembly. We hypothesize that a drawdown water regime enhances seed establishment compared to a year-round stable water level, that this increases species richness and diversity, and that this is modulated by species traits and shore morphology. Germination of 20 wetland plant species with different dispersal capacities (floating capacity expressed as seed floatation half-time) and soil moisture preferences for germination (Ellenberg F) was tested on artificial shores in 24 outdoor ponds in two complementary experiments over 8 weeks. The ‘dispersal experiment’ tested the effect of water regime on recruitment of hydrochorously dispersing seeds. The ‘seed bank experiment’ tested the effect of water regime on germination from a sown seed bank, on steep and gradual shores. In the dispersal experiment, the drawdown regime increased recruitment and species richness. Longer floating species colonized a larger shoreline section. Soil moisture preference for germination did not determine colonization patterns. In the seed bank experiment, the drawdown regime increased the number of seedlings on gradual sloping shores, but not on steep shores. The number of germinating seedlings corresponded to the area subjected to the drawdown regime in both shore types. Species richness was not affected by water regime or shore morphology, and species traits did not determine shoreline colonization. Most seeds germinated in moist soil conditions for all species. Synthesis. A spring drawdown instead of stable water regime stimulates establishment of hydrochorously dispersing seeds in temperate wetlands, leading to higher species richness and diversity. Germination from the seed bank is more affected by water regime and shore surface than by the tested species traits. Species traits, water levels and shore morphology together determine wetland plant community assembly, with dispersal as the main driver of seedling community diversity. Water-level regulations and shore morphology can be used to influence plant communities in wetland restoration.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2019-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {Leeuwen, Casper H. A. van and Sarneel, Judith M. and Paassen, José van and Rip, Winnie J. and Bakker, Elisabeth S.},\n\tyear = {2014},\n\tkeywords = {\\#nosource, Ellenberg, biodiversity, determinants of plant community diversity and structure, hydrochory, river, seed floatation, shore slope, soil moisture preference, wetland, zonation},\n\tpages = {998--1007},\n}\n\n\n\n\n\n Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination, and how these interactions determine plant community assembly. We hypothesize that a drawdown water regime enhances seed establishment compared to a year-round stable water level, that this increases species richness and diversity, and that this is modulated by species traits and shore morphology. Germination of 20 wetland plant species with different dispersal capacities (floating capacity expressed as seed floatation half-time) and soil moisture preferences for germination (Ellenberg F) was tested on artificial shores in 24 outdoor ponds in two complementary experiments over 8 weeks. The ‘dispersal experiment’ tested the effect of water regime on recruitment of hydrochorously dispersing seeds. The ‘seed bank experiment’ tested the effect of water regime on germination from a sown seed bank, on steep and gradual shores. In the dispersal experiment, the drawdown regime increased recruitment and species richness. Longer floating species colonized a larger shoreline section. Soil moisture preference for germination did not determine colonization patterns. In the seed bank experiment, the drawdown regime increased the number of seedlings on gradual sloping shores, but not on steep shores. The number of germinating seedlings corresponded to the area subjected to the drawdown regime in both shore types. Species richness was not affected by water regime or shore morphology, and species traits did not determine shoreline colonization. Most seeds germinated in moist soil conditions for all species. Synthesis. A spring drawdown instead of stable water regime stimulates establishment of hydrochorously dispersing seeds in temperate wetlands, leading to higher species richness and diversity. Germination from the seed bank is more affected by water regime and shore surface than by the tested species traits. Species traits, water levels and shore morphology together determine wetland plant community assembly, with dispersal as the main driver of seedling community diversity. Water-level regulations and shore morphology can be used to influence plant communities in wetland restoration.\n
\n\n\n\n \n\n \n \n \n \n \n \n Herbivores Enforce Sharp Boundaries Between Terrestrial and Aquatic Ecosystems.\n \n \n \n \n\n\n \n Sarneel, J. M.; Huig, N.; Veen, G. F.; Rip, W.; and Bakker, E. S.\n\n\n \n\n\n\n Ecosystems, 17(8): 1426–1438. December 2014.\n \n\n\n\n
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\n\n\n@article{sarneel_herbivores_2014,\n\ttitle = {Herbivores {Enforce} {Sharp} {Boundaries} {Between} {Terrestrial} and {Aquatic} {Ecosystems}},\n\tvolume = {17},\n\tissn = {1435-0629},\n\turl = {https://doi.org/10.1007/s10021-014-9805-1},\n\tdoi = {10.1007/s10021-014-9805-1},\n\tabstract = {The transitions between ecosystems (ecotones) are often biodiversity hotspots, but we know little about the forces that shape them. Today, often sharp boundaries with low diversity are found between terrestrial and aquatic ecosystems. This has been attributed to environmental factors that hamper succession. However, ecosystem properties are often controlled by both bottom-up and top-down forces, but their relative importance in shaping riparian boundaries is not known. We hypothesize that (1) herbivores may enforce sharp transitions between terrestrial and aquatic ecosystems by inhibiting emergent vegetation expansion and reducing the width of the transition zone and (2) the vegetation expansion, diversity, and species turnover are related to abiotic factors in the absence of herbivores, but not in their presence. We tested these hypotheses in 50 paired grazed and ungrazed plots spread over ten wetlands, during two years. Excluding grazers increased vegetation expansion, cover, biomass, and species richness. In ungrazed plots, vegetation cover was negatively related to water depth, whereas plant species richness was negatively related to the vegetation N:P ratio. The presence of (mainly aquatic) herbivores overruled the effect of water depth on vegetation cover increase but did not interact with vegetation N:P ratio. Increased local extinction in the presence of herbivores explained the negative effect of herbivores on species richness, as local colonization rates were unaffected by grazing. We conclude that (aquatic) herbivores can strongly inhibit expansion of the riparian vegetation and reduce vegetation diversity over a range of environmental conditions. Consequently, herbivores enforce sharp boundaries between terrestrial and aquatic ecosystems.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2019-03-27},\n\tjournal = {Ecosystems},\n\tauthor = {Sarneel, Judith M. and Huig, N. and Veen, G. F. and Rip, W. and Bakker, E. S.},\n\tmonth = dec,\n\tyear = {2014},\n\tkeywords = {\\#nosource, Biodiversity, ecotone, herbivory, nutrient availability, riparian vegetation, spatial patterns, species turnover, succession, transition zones, vegetation N:P ratio, water depth},\n\tpages = {1426--1438},\n}\n\n\n\n\n\n The transitions between ecosystems (ecotones) are often biodiversity hotspots, but we know little about the forces that shape them. Today, often sharp boundaries with low diversity are found between terrestrial and aquatic ecosystems. This has been attributed to environmental factors that hamper succession. However, ecosystem properties are often controlled by both bottom-up and top-down forces, but their relative importance in shaping riparian boundaries is not known. We hypothesize that (1) herbivores may enforce sharp transitions between terrestrial and aquatic ecosystems by inhibiting emergent vegetation expansion and reducing the width of the transition zone and (2) the vegetation expansion, diversity, and species turnover are related to abiotic factors in the absence of herbivores, but not in their presence. We tested these hypotheses in 50 paired grazed and ungrazed plots spread over ten wetlands, during two years. Excluding grazers increased vegetation expansion, cover, biomass, and species richness. In ungrazed plots, vegetation cover was negatively related to water depth, whereas plant species richness was negatively related to the vegetation N:P ratio. The presence of (mainly aquatic) herbivores overruled the effect of water depth on vegetation cover increase but did not interact with vegetation N:P ratio. Increased local extinction in the presence of herbivores explained the negative effect of herbivores on species richness, as local colonization rates were unaffected by grazing. We conclude that (aquatic) herbivores can strongly inhibit expansion of the riparian vegetation and reduce vegetation diversity over a range of environmental conditions. Consequently, herbivores enforce sharp boundaries between terrestrial and aquatic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Windows of opportunity for germination of riparian species after restoring water level fluctuations: a field experiment with controlled seed banks.\n \n \n \n \n\n\n \n Sarneel, J. M.; Janssen, R. H.; Rip, W. J.; Bender, I. M. A.; and Bakker, E. S.\n\n\n \n\n\n\n Journal of Applied Ecology, 51(4): 1006–1014. 2014.\n \n\n\n\n
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\n\n\n@article{sarneel_windows_2014,\n\ttitle = {Windows of opportunity for germination of riparian species after restoring water level fluctuations: a field experiment with controlled seed banks},\n\tvolume = {51},\n\tcopyright = {© 2014 The Authors. Journal of Applied Ecology © 2014 British Ecological Society},\n\tissn = {1365-2664},\n\tshorttitle = {Windows of opportunity for germination of riparian species after restoring water level fluctuations},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2664.12288},\n\tdoi = {10.1111/1365-2664.12288},\n\tabstract = {Restoration activities aiming at increasing vegetation diversity often try to stimulate both dispersal and germination. In wetlands, dispersal and germination are coupled as water and water level fluctuations (WLF) simultaneously influence seed transport and germination conditions (soil moisture). Water regime shifts have been shown to affect vegetation composition. However, the interactions between WLF, dispersal and subsequent germination as drivers of such changes are still poorly understood, especially within the complexity of a field situation. We tested the effect of soil moisture on ten riparian species in the greenhouse and sowed these species on 135 field locations in nine wetlands with recently restored WLF. We used quantile regressions to test the effects of WLF on the window of opportunity for germination from sown seeds and other seeds naturally dispersed to our plots, as well as on community diversity. Soil moisture significantly affected germination both in the greenhouse and in the field. In the complexity of a field situation, a flooding depth just below the soil level, an intermediate flooding duration and a high flooding frequency provided the best opportunities for maximal germination. This was because these conditions enhanced germination from the seed bank as well as increasing germination from dispersed seeds. Seedling diversity showed identical patterns. Other known (i.e., light conditions) and unknown factors played a role as we found low and variable germination, even under optimal conditions. We found evidence that WLF can affect vegetation zonation as flooded seedling communities contained more species with high moisture affinity. Synthesis and applications. Water level fluctuations provide clear windows of opportunity for germination both from the seed bank and from dispersed seeds. Water regime changes are therefore likely to strongly affect recruitment opportunities and subsequent community assembly in riparian ecosystems, for instance through climate change or management. Water level fluctuations can be used as management tool to stimulate plant recruitment and seedling diversity in riparian wetlands.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2019-03-27},\n\tjournal = {Journal of Applied Ecology},\n\tauthor = {Sarneel, Judith M. and Janssen, Roel H. and Rip, Winnie J. and Bender, Irene M. A. and Bakker, Elisabeth S.},\n\tyear = {2014},\n\tkeywords = {\\#nosource, community assembly, dispersal, diversity, flooding regime, hydrological changes, quantile regression, recruitment, vegetation zonation, water management},\n\tpages = {1006--1014},\n}\n\n\n\n\n\n Restoration activities aiming at increasing vegetation diversity often try to stimulate both dispersal and germination. In wetlands, dispersal and germination are coupled as water and water level fluctuations (WLF) simultaneously influence seed transport and germination conditions (soil moisture). Water regime shifts have been shown to affect vegetation composition. However, the interactions between WLF, dispersal and subsequent germination as drivers of such changes are still poorly understood, especially within the complexity of a field situation. We tested the effect of soil moisture on ten riparian species in the greenhouse and sowed these species on 135 field locations in nine wetlands with recently restored WLF. We used quantile regressions to test the effects of WLF on the window of opportunity for germination from sown seeds and other seeds naturally dispersed to our plots, as well as on community diversity. Soil moisture significantly affected germination both in the greenhouse and in the field. In the complexity of a field situation, a flooding depth just below the soil level, an intermediate flooding duration and a high flooding frequency provided the best opportunities for maximal germination. This was because these conditions enhanced germination from the seed bank as well as increasing germination from dispersed seeds. Seedling diversity showed identical patterns. Other known (i.e., light conditions) and unknown factors played a role as we found low and variable germination, even under optimal conditions. We found evidence that WLF can affect vegetation zonation as flooded seedling communities contained more species with high moisture affinity. Synthesis and applications. Water level fluctuations provide clear windows of opportunity for germination both from the seed bank and from dispersed seeds. Water regime changes are therefore likely to strongly affect recruitment opportunities and subsequent community assembly in riparian ecosystems, for instance through climate change or management. Water level fluctuations can be used as management tool to stimulate plant recruitment and seedling diversity in riparian wetlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n No evidence for assortative mating within a willow warbler migratory divide.\n \n \n \n \n\n\n \n Liedvogel, M.; Larson, K. W.; Lundberg, M.; Gursoy, A.; Wassenaar, L. I.; Hobson, K. A.; Bensch, S.; and Åkesson, S.\n\n\n \n\n\n\n Frontiers in Zoology, 11(1): 52. July 2014.\n 00005\n\n\n\n
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\n\n\n@article{liedvogel_no_2014,\n\ttitle = {No evidence for assortative mating within a willow warbler migratory divide},\n\tvolume = {11},\n\tcopyright = {2014 Liedvogel et al.},\n\tissn = {1742-9994},\n\turl = {http://www.frontiersinzoology.com/content/11/1/52/abstract},\n\tdoi = {10.1186/s12983-014-0052-2},\n\tabstract = {In contact zones, genetic mixing of two taxa can be restricted by prezygotic (e.g. assortative mating) or postzygotic (lower fitness of hybrid offspring) barriers, or a combination of the two. A hybrid zone between two willow warbler subspecies (Phylloscopus trochilus trochilus, P. t. acredula) with distinctive migratory strategies occurs in central Sweden. These subspecies exhibit differences in migratory direction and distance, resulting in geographically distinct wintering areas in Africa. The subspecies may have diverged from a common refuge after the last ice age, and neutral genetic markers are homogeneous across their range. By contrast, several phenotypic traits and genetic markers of two chromosomal regions previously identified show steep clines across the divide. The evolutionary forces that maintain this migratory divide remain unknown. Here we use plumage colour, morphology, genetic markers and feather stable nitrogen-isotopes (δ\n 15N) to assess if assortative mating between migratory phenotypes could be acting as a possible mechanism for keeping the two forms genetically separate and maintaining the migratory divide. We colour-ringed a willow warbler breeding population in the central part of the hybrid zone and observed the breeding population to assess phenotypic and genotypic traits of social pairs.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2014-07-24},\n\tjournal = {Frontiers in Zoology},\n\tauthor = {Liedvogel, Miriam and Larson, Keith W. and Lundberg, Max and Gursoy, Arzu and Wassenaar, Leonard I. and Hobson, Keith A. and Bensch, Staffan and Åkesson, Susanne},\n\tmonth = jul,\n\tyear = {2014},\n\tnote = {00005},\n\tkeywords = {\\#nosource, Nitrogen-15, Phylloscopus trochilus, Postzygotic selection, Prezygotic selection, Willow warbler, hybrid zone, reproductive isolation},\n\tpages = {52},\n}\n\n\n\n\n\n In contact zones, genetic mixing of two taxa can be restricted by prezygotic (e.g. assortative mating) or postzygotic (lower fitness of hybrid offspring) barriers, or a combination of the two. A hybrid zone between two willow warbler subspecies (Phylloscopus trochilus trochilus, P. t. acredula) with distinctive migratory strategies occurs in central Sweden. These subspecies exhibit differences in migratory direction and distance, resulting in geographically distinct wintering areas in Africa. The subspecies may have diverged from a common refuge after the last ice age, and neutral genetic markers are homogeneous across their range. By contrast, several phenotypic traits and genetic markers of two chromosomal regions previously identified show steep clines across the divide. The evolutionary forces that maintain this migratory divide remain unknown. Here we use plumage colour, morphology, genetic markers and feather stable nitrogen-isotopes (δ 15N) to assess if assortative mating between migratory phenotypes could be acting as a possible mechanism for keeping the two forms genetically separate and maintaining the migratory divide. We colour-ringed a willow warbler breeding population in the central part of the hybrid zone and observed the breeding population to assess phenotypic and genotypic traits of social pairs.\n
\n\n\n\n \n\n \n \n \n \n \n \n The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire: Decadal effects assessed using 210Pb peat chronologies.\n \n \n \n \n\n\n \n Olid, C.; Nilsson, M. B.; Eriksson, T.; and Klaminder, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 119(3): 2013JG002365. March 2014.\n 00008\n\n\n\n
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\n\n\n@article{olid_effects_2014,\n\ttitle = {The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire: {Decadal} effects assessed using {210Pb} peat chronologies},\n\tvolume = {119},\n\tissn = {2169-8961},\n\tshorttitle = {The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/2013JG002365/abstract},\n\tdoi = {10.1002/2013JG002365},\n\tabstract = {Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6°C) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20 kg ha−1 yr−1, respectively) over 12 years of field treatments in a boreal mire. An empirical mass balance model was applied to 210Pb-dated peat cores to evaluate changes in C inputs, C mass loss, and net C accumulation rates in response to the treatments. We found that (i) none of the treatments generated a significant effect on peat mass loss decay rates, (ii) C input rates were positively affected by N additions and negatively affected by S additions, (iii) the C accumulation rate in the uppermost (10 to 12 cm) peat was increased by N additions and decreased by S additions, and (iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-04-28},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Olid, Carolina and Nilsson, Mats B. and Eriksson, Tobias and Klaminder, Jonatan},\n\tmonth = mar,\n\tyear = {2014},\n\tnote = {00008},\n\tkeywords = {\\#nosource, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, 0497 Wetlands, 1115 Radioisotope geochronology, 1630 Impacts of global change, 210Pb, Mire, Nitrogen, carbon, climate change, temperature},\n\tpages = {2013JG002365},\n}\n\n\n\n\n\n Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6°C) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20 kg ha−1 yr−1, respectively) over 12 years of field treatments in a boreal mire. An empirical mass balance model was applied to 210Pb-dated peat cores to evaluate changes in C inputs, C mass loss, and net C accumulation rates in response to the treatments. We found that (i) none of the treatments generated a significant effect on peat mass loss decay rates, (ii) C input rates were positively affected by N additions and negatively affected by S additions, (iii) the C accumulation rate in the uppermost (10 to 12 cm) peat was increased by N additions and decreased by S additions, and (iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low.\n
\n\n\n\n \n\n \n \n \n \n \n \n Allelic Variation in a Willow Warbler Genomic Region Is Associated with Climate Clines.\n \n \n \n \n\n\n \n Larson, K. W.; Liedvogel, M.; Addison, B.; Kleven, O.; Laskemoen, T.; Lifjeld, J. T.; Lundberg, M.; Åkesson, S.; and Bensch, S.\n\n\n \n\n\n\n PLoS ONE, 9(5): e95252. May 2014.\n 00004\n\n\n\n
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\n\n\n\n@article{larson_allelic_2014,\n\ttitle = {Allelic {Variation} in a {Willow} {Warbler} {Genomic} {Region} {Is} {Associated} with {Climate} {Clines}},\n\tvolume = {9},\n\tissn = {1932-6203},\n\turl = {http://dx.plos.org/10.1371/journal.pone.0095252},\n\tdoi = {10.1371/journal.pone.0095252},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2014-05-06},\n\tjournal = {PLoS ONE},\n\tauthor = {Larson, Keith W. and Liedvogel, Miriam and Addison, BriAnne and Kleven, Oddmund and Laskemoen, Terje and Lifjeld, Jan T. and Lundberg, Max and Åkesson, Susanne and Bensch, Staffan},\n\teditor = {Janke, Axel},\n\tmonth = may,\n\tyear = {2014},\n\tnote = {00004},\n\tkeywords = {\\#nosource},\n\tpages = {e95252},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Northern peatland Collembola communities unaffected by three summers of simulated extreme precipitation.\n \n \n \n \n\n\n \n Krab, E. J.; Aerts, R.; Berg, M. P.; van Hal, J.; and Keuper, F.\n\n\n \n\n\n\n Applied Soil Ecology, 79: 70–76. July 2014.\n 00004\n\n\n\n
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\n\n\n@article{krab_northern_2014,\n\ttitle = {Northern peatland {Collembola} communities unaffected by three summers of simulated extreme precipitation},\n\tvolume = {79},\n\tissn = {0929-1393},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0929139314000821},\n\tdoi = {10.1016/j.apsoil.2014.03.007},\n\tabstract = {Extreme climate events are observed and predicted to increase in frequency and duration in high-latitude ecosystems as a result of global climate change. This includes extreme precipitation events, which may directly impact on belowground food webs and ecosystem functioning by their physical impacts and by altering local soil moisture conditions.\nWe assessed responses of the Collembola community in a northern Sphagnum fuscum-dominated ombrotrophic peatland to three years of experimentally increased occurrence of extreme precipitation events. Annual summer precipitation was doubled (an increase of 200 mm) by 16 simulated extreme rain events within the three months growing season, where on each occasion 12.5 mm of rain was added within a few minutes. Despite this high frequency and intensity of the rain events, no shifts in Collembola density, relative species abundances and community weighted means of three relevant traits (moisture preference, vertical distribution and body size) were observed. This strongly suggests that the peatland Collembola community is unaffected by the physical impacts of extreme precipitation and the short-term variability in moisture conditions. The lack of response is most likely reinforced by the fact that extreme precipitation events do not seem to alter longer-term soil moisture conditions in the peat layers inhabited by soil fauna.\nThis study adds evidence to the observation that the biotic components of northern ombrotrophic peatlands are hardly responsive to an increase in extreme summer precipitation events. Given the importance of these ecosystems for the global C balance, these findings significantly contribute to the current knowledge of the ecological impact of future climate scenarios.},\n\turldate = {2017-02-08},\n\tjournal = {Applied Soil Ecology},\n\tauthor = {Krab, Eveline J. and Aerts, Rien and Berg, Matty P. and van Hal, Jurgen and Keuper, Frida},\n\tmonth = jul,\n\tyear = {2014},\n\tnote = {00004},\n\tkeywords = {\\#nosource, Community weighted mean, Extreme events, Functional traits, Peat bog, Soil fauna, precipitation},\n\tpages = {70--76},\n}\n\n\n\n\n\n Extreme climate events are observed and predicted to increase in frequency and duration in high-latitude ecosystems as a result of global climate change. This includes extreme precipitation events, which may directly impact on belowground food webs and ecosystem functioning by their physical impacts and by altering local soil moisture conditions. We assessed responses of the Collembola community in a northern Sphagnum fuscum-dominated ombrotrophic peatland to three years of experimentally increased occurrence of extreme precipitation events. Annual summer precipitation was doubled (an increase of 200 mm) by 16 simulated extreme rain events within the three months growing season, where on each occasion 12.5 mm of rain was added within a few minutes. Despite this high frequency and intensity of the rain events, no shifts in Collembola density, relative species abundances and community weighted means of three relevant traits (moisture preference, vertical distribution and body size) were observed. This strongly suggests that the peatland Collembola community is unaffected by the physical impacts of extreme precipitation and the short-term variability in moisture conditions. The lack of response is most likely reinforced by the fact that extreme precipitation events do not seem to alter longer-term soil moisture conditions in the peat layers inhabited by soil fauna. This study adds evidence to the observation that the biotic components of northern ombrotrophic peatlands are hardly responsive to an increase in extreme summer precipitation events. Given the importance of these ecosystems for the global C balance, these findings significantly contribute to the current knowledge of the ecological impact of future climate scenarios.\n
\n\n\n\n \n\n \n \n \n \n \n \n High-throughput sequencing shows inconsistent results with a microscope-based analysis of the soil prokaryotic community.\n \n \n \n \n\n\n \n Ushio, M.; Makoto, K.; Klaminder, J.; Takasu, H.; and Nakano, S.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 76: 53–56. September 2014.\n 00008\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{ushio_high-throughput_2014,\n\ttitle = {High-throughput sequencing shows inconsistent results with a microscope-based analysis of the soil prokaryotic community},\n\tvolume = {76},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071714001709},\n\tdoi = {10.1016/j.soilbio.2014.05.010},\n\tabstract = {In the present study, we perform the first direct analysis on how the composition of the prokaryotic soil community differs depending on whether high-throughput sequencing or fluorescent in situ hybridization (FISH) coupled with catalyzed reporter deposition (CARD) is used. Soil samples were collected along short (\\<3 m) tundra vegetation gradients from Northern Sweden. Relative abundances of Acidobacteria and Bacteroidetes estimated by the high-throughput sequencing were higher than those estimated by CARD–FISH, while relative abundances of Archaea and α-Proteobacteria estimated by high-throughput sequencing were lower than those estimated by CARD–FISH. The results indicated that the high-throughput sequencing overestimates/underestimates the relative abundance of some microbial taxa if we assume that CARD–FISH can provide potentially more quantitative data. Great caution should be taken when interpreting data generated by molecular technologies (both of high-throughput sequencing and CARD–FISH), and supports by multiple approaches are necessary to make a robust conclusion.},\n\turldate = {2017-02-07},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Ushio, Masayuki and Makoto, Kobayashi and Klaminder, Jonatan and Takasu, Hiroyuki and Nakano, Shin-ichi},\n\tmonth = sep,\n\tyear = {2014},\n\tnote = {00008},\n\tkeywords = {\\#nosource, Archaea, CARD–FISH, High-throughput sequencing, Soil prokaryotic community, Tundra ecosystem, bacteria},\n\tpages = {53--56},\n}\n\n\n\n\n\n In the present study, we perform the first direct analysis on how the composition of the prokaryotic soil community differs depending on whether high-throughput sequencing or fluorescent in situ hybridization (FISH) coupled with catalyzed reporter deposition (CARD) is used. Soil samples were collected along short (<3 m) tundra vegetation gradients from Northern Sweden. Relative abundances of Acidobacteria and Bacteroidetes estimated by the high-throughput sequencing were higher than those estimated by CARD–FISH, while relative abundances of Archaea and α-Proteobacteria estimated by high-throughput sequencing were lower than those estimated by CARD–FISH. The results indicated that the high-throughput sequencing overestimates/underestimates the relative abundance of some microbial taxa if we assume that CARD–FISH can provide potentially more quantitative data. Great caution should be taken when interpreting data generated by molecular technologies (both of high-throughput sequencing and CARD–FISH), and supports by multiple approaches are necessary to make a robust conclusion.\n
\n\n\n\n \n\n \n \n \n \n \n \n Using Short-lived Radionuclides to Estimate Rates of Soil Motion in Frost Boils.\n \n \n \n \n\n\n \n Klaminder, J.; Yoo, K.; Olid, C.; Ramebäck, H.; and Vesterlund, A.\n\n\n \n\n\n\n Permafrost and Periglacial Processes, 25(3): 184–193. July 2014.\n 00005\n\n\n\n
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\n\n\n@article{klaminder_using_2014,\n\ttitle = {Using {Short}-lived {Radionuclides} to {Estimate} {Rates} of {Soil} {Motion} in {Frost} {Boils}},\n\tvolume = {25},\n\tissn = {1099-1530},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/ppp.1811/abstract},\n\tdoi = {10.1002/ppp.1811},\n\tabstract = {Cryoturbation in high-latitude soils is crucial for the long-term cycling of elements, but the rates of soil motion are poorly constrained. Here, we test whether the rate of frost creep, soil erosion and vertical soil mixing in frost boils can be estimated using short-lived radionuclides (137Cs and 210Pb). We find a small-scale variation in 137Cs and 210Pb inventories in the lower levels of the eroding regions of frost boils in comparison to the expected depositional sites; hence, the distribution of the radionuclides appears to reflect a lateral transport of atmospheric fallout from the centre of the boil (inner domain) towards the surrounding soil (outer domain). 14C dating of the soil indicates that fallout of 137Cs was mobile in the soil and that 210Pb moved with the soil matrix. A soil creep model and a surface soil erosion model are derived and applied to the lateral and vertical distributions of 210Pb in the frost boil. Both models predict the expected trajectories of soil motion and provide rates of creep, erosion and mixing at a mm yr−1 to cm yr−1 scale. The distribution of 210Pb provides new insights about the processes and rates of soil mass movement in frost boils, if sound mass-balance models are applied. Copyright © 2014 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {Permafrost and Periglacial Processes},\n\tauthor = {Klaminder, J. and Yoo, K. and Olid, C. and Ramebäck, H. and Vesterlund, A.},\n\tmonth = jul,\n\tyear = {2014},\n\tnote = {00005},\n\tkeywords = {\\#nosource, Cryoturbation, carbon-14, cesium-137, frost boils, lead-210},\n\tpages = {184--193},\n}\n\n\n\n\n\n Cryoturbation in high-latitude soils is crucial for the long-term cycling of elements, but the rates of soil motion are poorly constrained. Here, we test whether the rate of frost creep, soil erosion and vertical soil mixing in frost boils can be estimated using short-lived radionuclides (137Cs and 210Pb). We find a small-scale variation in 137Cs and 210Pb inventories in the lower levels of the eroding regions of frost boils in comparison to the expected depositional sites; hence, the distribution of the radionuclides appears to reflect a lateral transport of atmospheric fallout from the centre of the boil (inner domain) towards the surrounding soil (outer domain). 14C dating of the soil indicates that fallout of 137Cs was mobile in the soil and that 210Pb moved with the soil matrix. A soil creep model and a surface soil erosion model are derived and applied to the lateral and vertical distributions of 210Pb in the frost boil. Both models predict the expected trajectories of soil motion and provide rates of creep, erosion and mixing at a mm yr−1 to cm yr−1 scale. The distribution of 210Pb provides new insights about the processes and rates of soil mass movement in frost boils, if sound mass-balance models are applied. Copyright © 2014 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n Fish introductions reveal the temperature dependence of species interactions.\n \n \n \n\n\n \n Hein, C. L.; Oehlund, G.; and Englund, G.\n\n\n \n\n\n\n Proceedings of the Royal Society B-Biological Sciences, 281(1775): 20132641. January 2014.\n 00019\n\n\n\n
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\n\n\n@article{hein_fish_2014,\n\ttitle = {Fish introductions reveal the temperature dependence of species interactions},\n\tvolume = {281},\n\tissn = {0962-8452},\n\tdoi = {10.1098/rspb.2013.2641},\n\tabstract = {A major area of current research is to understand how climate change will impact species interactions and ultimately biodiversity. A variety of environmental conditions are rapidly changing owing to climate warming, and these conditions often affect both the strength and outcome of species interactions. We used fish distributions and replicated fish introductions to investigate environmental conditions influencing the coexistence of two fishes in Swedish lakes: brown trout (Salmo trutta) and pike (Esox lucius). A logistic regression model of brown trout and pike coexistence showed that these species coexist in large lakes (more than 4.5 km(2)), but not in small, warm lakes (annual air temperature more than 0.9-1.5 degrees C). We then explored how climate change will alter coexistence by substituting climate scenarios for 2091-2100 into our model. The model predicts that brown trout will be extirpated from approximately half of the lakes where they presently coexist with pike and from nearly all 9100 lakes where pike are predicted to invade. Context dependency was critical for understanding pike-brown trout interactions, and, given the widespread occurrence of context-dependent species interactions, this aspect will probably be critical for accurately predicting climate impacts on biodiversity.},\n\tlanguage = {English},\n\tnumber = {1775},\n\tjournal = {Proceedings of the Royal Society B-Biological Sciences},\n\tauthor = {Hein, Catherine L. and Oehlund, Gunnar and Englund, Goeran},\n\tmonth = jan,\n\tyear = {2014},\n\tnote = {00019},\n\tkeywords = {\\#nosource, animal ecology, arctic charr, biotic interactions, brown trout, climate change, climate-change, coexistence, context dependency, food-web, pike esox-lucius, salvelinus-alpinus, species distribution models, trout salmo-trutta, water temperature},\n\tpages = {20132641},\n}\n\n\n\n\n\n A major area of current research is to understand how climate change will impact species interactions and ultimately biodiversity. A variety of environmental conditions are rapidly changing owing to climate warming, and these conditions often affect both the strength and outcome of species interactions. We used fish distributions and replicated fish introductions to investigate environmental conditions influencing the coexistence of two fishes in Swedish lakes: brown trout (Salmo trutta) and pike (Esox lucius). A logistic regression model of brown trout and pike coexistence showed that these species coexist in large lakes (more than 4.5 km(2)), but not in small, warm lakes (annual air temperature more than 0.9-1.5 degrees C). We then explored how climate change will alter coexistence by substituting climate scenarios for 2091-2100 into our model. The model predicts that brown trout will be extirpated from approximately half of the lakes where they presently coexist with pike and from nearly all 9100 lakes where pike are predicted to invade. Context dependency was critical for understanding pike-brown trout interactions, and, given the widespread occurrence of context-dependent species interactions, this aspect will probably be critical for accurately predicting climate impacts on biodiversity.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant and microbial responses to nitrogen and phosphorus addition across an elevational gradient in subarctic tundra.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Liu, Z.; Giesler, R.; and Wardle, D. A.\n\n\n \n\n\n\n Ecology, 95(7): 1819–1835. July 2014.\n 00025\n\n\n\n
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\n\n\n@article{sundqvist_plant_2014,\n\ttitle = {Plant and microbial responses to nitrogen and phosphorus addition across an elevational gradient in subarctic tundra},\n\tvolume = {95},\n\tissn = {1939-9170},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/13-0869.1/abstract},\n\tdoi = {10.1890/13-0869.1},\n\tabstract = {Temperature and nutrients are major limiting factors in subarctic tundra. Experimental manipulation of nutrient availability along elevational gradients (and thus temperature) can improve our understanding of ecological responses to climate change. However, no study to date has explored impacts of nutrient addition along a tundra elevational gradient, or across contrasting vegetation types along any elevational gradient. We set up a full factorial nitrogen (N) and phosphorus (P) fertilization experiment in each of two vegetation types (heath and meadow) at 500 m, 800 m, and 1000 m elevation in northern Swedish tundra. We predicted that plant and microbial communities in heath or at lower elevations would be more responsive to N addition while communities in meadow or at higher elevations would be more responsive to P addition, and that fertilizer effects would vary more with elevation for the heath than for the meadow. Although our results provided little support for these predictions, the relationship between nutrient limitation and elevation differed between vegetation types. Most plant and microbial properties were responsive to N and/or P fertilization, but responses often varied with elevation and/or vegetation type. For instance, vegetation density significantly increased with N + P fertilization relative to the other fertilizer treatments, and this increase was greatest at the lowest elevation for the heath but at the highest elevation for the meadow. Arbuscular mycorrhizae decreased with P fertilization at 500 m for the meadow, but with all fertilizer treatments in both vegetation types at 800 m. Fungal to bacterial ratios were enhanced by N + P fertilization for the two highest elevations in the meadow only. Additionally, microbial responses to fertilization were primarily direct rather than indirect via plant responses, pointing to a decoupled response of plant and microbial communities to nutrient addition and elevation. Because our study shows how two community types differ in their responses to fertilization and elevation, and because the temperature range across this gradient is ∼3°C, our study is informative about how nutrient limitation in tundra may be influenced by temperature shifts that are comparable to those expected under climate change during this century.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-07},\n\tjournal = {Ecology},\n\tauthor = {Sundqvist, Maja K. and Liu, Zhanfeng and Giesler, Reiner and Wardle, David A.},\n\tmonth = jul,\n\tyear = {2014},\n\tnote = {00025},\n\tkeywords = {\\#nosource, above- and belowground communities, fertilization experiment, fungal-to-bacterial ratios, global warming, plant functional groups, plant–soil linkages},\n\tpages = {1819--1835},\n}\n\n\n\n\n\n Temperature and nutrients are major limiting factors in subarctic tundra. Experimental manipulation of nutrient availability along elevational gradients (and thus temperature) can improve our understanding of ecological responses to climate change. However, no study to date has explored impacts of nutrient addition along a tundra elevational gradient, or across contrasting vegetation types along any elevational gradient. We set up a full factorial nitrogen (N) and phosphorus (P) fertilization experiment in each of two vegetation types (heath and meadow) at 500 m, 800 m, and 1000 m elevation in northern Swedish tundra. We predicted that plant and microbial communities in heath or at lower elevations would be more responsive to N addition while communities in meadow or at higher elevations would be more responsive to P addition, and that fertilizer effects would vary more with elevation for the heath than for the meadow. Although our results provided little support for these predictions, the relationship between nutrient limitation and elevation differed between vegetation types. Most plant and microbial properties were responsive to N and/or P fertilization, but responses often varied with elevation and/or vegetation type. For instance, vegetation density significantly increased with N + P fertilization relative to the other fertilizer treatments, and this increase was greatest at the lowest elevation for the heath but at the highest elevation for the meadow. Arbuscular mycorrhizae decreased with P fertilization at 500 m for the meadow, but with all fertilizer treatments in both vegetation types at 800 m. Fungal to bacterial ratios were enhanced by N + P fertilization for the two highest elevations in the meadow only. Additionally, microbial responses to fertilization were primarily direct rather than indirect via plant responses, pointing to a decoupled response of plant and microbial communities to nutrient addition and elevation. Because our study shows how two community types differ in their responses to fertilization and elevation, and because the temperature range across this gradient is ∼3°C, our study is informative about how nutrient limitation in tundra may be influenced by temperature shifts that are comparable to those expected under climate change during this century.\n
\n\n\n\n \n\n \n \n \n \n \n \n Consequences of warming on tundra carbon balance determined by reindeer grazing history.\n \n \n \n \n\n\n \n Väisänen, M.; Ylänne, H.; Kaarlejärvi, E.; Sjögersten, S.; Olofsson, J.; Crout, N.; and Stark, S.\n\n\n \n\n\n\n Nature Climate Change, 4(5): 384–388. May 2014.\n 00026\n\n\n\n
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\n\n\n@article{vaisanen_consequences_2014,\n\ttitle = {Consequences of warming on tundra carbon balance determined by reindeer grazing history},\n\tvolume = {4},\n\tcopyright = {© 2014 Nature Publishing Group},\n\tissn = {1758-678X},\n\turl = {http://www.nature.com/nclimate/journal/v4/n5/full/nclimate2147.html},\n\tdoi = {10.1038/nclimate2147},\n\tabstract = {Arctic tundra currently stores half of the global soil carbon (C) stock. Climate warming in the Arctic may lead to accelerated CO2 release through enhanced decomposition and turn Arctic ecosystems from a net C sink into a net C source, if warming enhances decomposition more than plant photosynthesis. A large portion of the circumpolar Arctic is grazed by reindeer/caribou, and grazing causes important vegetation shifts in the long-term. Using a unique experimental set-up, where areas experiencing more than 50 years of either light (LG) or heavy (HG) grazing were warmed and/or fertilized, we show that under ambient conditions areas under LG were a 70\\% stronger C sink than HG areas. Although warming decreased the C sink by 38\\% under LG, it had no effect under HG. Grazing history will thus be an important determinant in the response of ecosystem C balance to climate warming, which at present is not taken into account in climate change models.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-08},\n\tjournal = {Nature Climate Change},\n\tauthor = {Väisänen, Maria and Ylänne, Henni and Kaarlejärvi, Elina and Sjögersten, Sofie and Olofsson, Johan and Crout, Neil and Stark, Sari},\n\tmonth = may,\n\tyear = {2014},\n\tnote = {00026},\n\tkeywords = {\\#nosource, Climate-change ecology, Climate-change impacts},\n\tpages = {384--388},\n}\n\n\n\n\n\n Arctic tundra currently stores half of the global soil carbon (C) stock. Climate warming in the Arctic may lead to accelerated CO2 release through enhanced decomposition and turn Arctic ecosystems from a net C sink into a net C source, if warming enhances decomposition more than plant photosynthesis. A large portion of the circumpolar Arctic is grazed by reindeer/caribou, and grazing causes important vegetation shifts in the long-term. Using a unique experimental set-up, where areas experiencing more than 50 years of either light (LG) or heavy (HG) grazing were warmed and/or fertilized, we show that under ambient conditions areas under LG were a 70% stronger C sink than HG areas. Although warming decreased the C sink by 38% under LG, it had no effect under HG. Grazing history will thus be an important determinant in the response of ecosystem C balance to climate warming, which at present is not taken into account in climate change models.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal variation in nitrogen fixation and effects of climate change in a subarctic heath.\n \n \n \n \n\n\n \n Lett, S.; and Michelsen, A.\n\n\n \n\n\n\n Plant and Soil, 379(1-2): 193–204. June 2014.\n 00005\n\n\n\n
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\n\n\n@article{lett_seasonal_2014,\n\ttitle = {Seasonal variation in nitrogen fixation and effects of climate change in a subarctic heath},\n\tvolume = {379},\n\tissn = {0032-079X, 1573-5036},\n\turl = {http://link.springer.com/article/10.1007/s11104-014-2031-y},\n\tdoi = {10.1007/s11104-014-2031-y},\n\tabstract = {Background and aimsNitrogen fixation associated with cryptogams is potentially very important in arctic and subarctic terrestrial ecosystems, as it is a source of new nitrogen (N) into these highly N limited systems. Moss-, lichen- and legume-associated N2 fixation was studied with high frequency (every second week) during spring, summer, autumn and early winter to uncover the seasonal variation in input of atmospheric N2 to a subarctic heath with an altered climate.MethodsWe estimated N2 fixation from ethylene production by acetylene reduction assay in situ in a field experiment with the treatments: long- vs. short-term summer warming using plastic tents and litter addition (simulating expansion of the birch forest).ResultsN2 fixation activity was measured from late April to mid November and 33 \\% of all N2 was fixed outside the vascular plant growing season (Jun–Aug). This substantial amount underlines the importance of N2 fixation in the cold period. Warming increased N2 fixation two- to fivefold during late spring. However, long-term summer warming tended to decrease N2 fixation outside the treatment (tents present) period. Litter alone did not alter N2 fixation but in combination with warming N2 fixation increased, probably because N2 fixation became phosphorus limited under higher temperatures, which was alleviated by the P supply from the litter.ConclusionIn subarctic heath, the current N2 fixation period extends far beyond the vascular plant growing season. Climate warming and indirect effects such as vegetation changes affect the process of N2 fixation in different directions and thereby complicate predictions of future N cycling.},\n\tlanguage = {en},\n\tnumber = {1-2},\n\turldate = {2017-02-08},\n\tjournal = {Plant and Soil},\n\tauthor = {Lett, Signe and Michelsen, Anders},\n\tmonth = jun,\n\tyear = {2014},\n\tnote = {00005},\n\tkeywords = {\\#nosource, Bryophytes, Global change, Lichens, Litter addition, Long- vs. short-term warming, Nitrogen and phosphorus, PLANT physiology, Plant Sciences, Plant cover, Soil Science \\& Conservation, ecology},\n\tpages = {193--204},\n}\n\n\n\n\n\n Background and aimsNitrogen fixation associated with cryptogams is potentially very important in arctic and subarctic terrestrial ecosystems, as it is a source of new nitrogen (N) into these highly N limited systems. Moss-, lichen- and legume-associated N2 fixation was studied with high frequency (every second week) during spring, summer, autumn and early winter to uncover the seasonal variation in input of atmospheric N2 to a subarctic heath with an altered climate.MethodsWe estimated N2 fixation from ethylene production by acetylene reduction assay in situ in a field experiment with the treatments: long- vs. short-term summer warming using plastic tents and litter addition (simulating expansion of the birch forest).ResultsN2 fixation activity was measured from late April to mid November and 33 % of all N2 was fixed outside the vascular plant growing season (Jun–Aug). This substantial amount underlines the importance of N2 fixation in the cold period. Warming increased N2 fixation two- to fivefold during late spring. However, long-term summer warming tended to decrease N2 fixation outside the treatment (tents present) period. Litter alone did not alter N2 fixation but in combination with warming N2 fixation increased, probably because N2 fixation became phosphorus limited under higher temperatures, which was alleviated by the P supply from the litter.ConclusionIn subarctic heath, the current N2 fixation period extends far beyond the vascular plant growing season. Climate warming and indirect effects such as vegetation changes affect the process of N2 fixation in different directions and thereby complicate predictions of future N cycling.\n
\n\n\n\n \n\n \n \n \n \n \n \n Multi-proxy study of soil organic matter dynamics in permafrost peat deposits reveal vulnerability to climate change in the European Russian Arctic.\n \n \n \n \n\n\n \n Routh, J.; Hugelius, G.; Kuhry, P.; Filley, T.; Tillman, P. K.; Becher, M.; and Crill, P.\n\n\n \n\n\n\n Chemical Geology, 368: 104–117. March 2014.\n 00023\n\n\n\n
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\n\n\n@article{routh_multi-proxy_2014,\n\ttitle = {Multi-proxy study of soil organic matter dynamics in permafrost peat deposits reveal vulnerability to climate change in the {European} {Russian} {Arctic}},\n\tvolume = {368},\n\tissn = {0009-2541},\n\turl = {https://www.sciencedirect.com/science/article/pii/S000925411400014X},\n\tdoi = {10.1016/j.chemgeo.2013.12.022},\n\tabstract = {Soil organic carbon (SOC) in permafrost terrain is vulnerable to climate change. Perennially frozen peat deposits store large amounts of SOC, but we know little about its chemical composition and lability. We used plant macrofossil and biomarker analyses to reconstruct the Holocene paleovegetation and paleoenvironmental changes in two peat plateau profiles from the European Russian Arctic. Peat plateaus are the main stores of permafrost soil C in the region, but during most of the Holocene peats developed as permafrost-free rich fens with woody vegetation, sedges and mosses. Around 2200 cal BP, permafrost aggraded at the site resulting in frost heave and a drastic reduction in peat accumulation under the drier uplifted surface conditions. The permafrost dynamics (aggradation, frost-heave and thaw) ushered changes in plant assemblages and carbon accumulation, and consequently in the biomarker trends too.\nDetailed biomarker analyses indicate abundant neutral lipids, which follow the general pattern: n-alkanols \\> sterols ≥ n-alkanes ≥ triterpenols. The lignin monomers are not as abundant as the lipids and increase with depth. The selected aliphatic and phenolic compounds are source specific, and they have different degrees of lability, which is useful for tracing the impact of permafrost dynamics (peat accumulation and/or decay associated with thawing). However, common interpretation of biomarker patterns, and perceived hydrological and climate changes, must be applied carefully in permafrost regions. The increased proportion (selective preservation) of n-alkanes and lignin is a robust indicator of cumulative decomposition trajectories, which is mirrored by functional compounds (e.g. n-alkanol, triterpenol, and sterol concentrations) showing opposite trends. The distribution of these compounds follows first order decay kinetics, and concurs with the downcore diagenetic changes. In particular, some of the biomarker ratios (e.g. stanol/sterol and higher plant alkane index) seem promising for tracing SOC decomposition despite changes in botanical imprint, and sites spanning across different soil types and locations. Carbon accumulation rate calculated at these sites varies from 18.1 to 31.1 gC m− 2 yr− 1, and it's evident selective preservation, molecular complexity of organic compounds, and freezing conditions enhance the long-term stability of SOC. Further, our results suggest that permafrost dynamics strongly impact the more undecomposed SOC that could be rapidly remobilized through ongoing thermokarst expansion.},\n\turldate = {2017-02-07},\n\tjournal = {Chemical Geology},\n\tauthor = {Routh, Joyanto and Hugelius, Gustaf and Kuhry, Peter and Filley, Timothy and Tillman, Päivi Kaislahti and Becher, Marina and Crill, Patrick},\n\tmonth = mar,\n\tyear = {2014},\n\tnote = {00023},\n\tkeywords = {\\#nosource, Biomarkers, Holocene, carbon, lability, peat, permafrost},\n\tpages = {104--117},\n}\n\n\n\n\n\n Soil organic carbon (SOC) in permafrost terrain is vulnerable to climate change. Perennially frozen peat deposits store large amounts of SOC, but we know little about its chemical composition and lability. We used plant macrofossil and biomarker analyses to reconstruct the Holocene paleovegetation and paleoenvironmental changes in two peat plateau profiles from the European Russian Arctic. Peat plateaus are the main stores of permafrost soil C in the region, but during most of the Holocene peats developed as permafrost-free rich fens with woody vegetation, sedges and mosses. Around 2200 cal BP, permafrost aggraded at the site resulting in frost heave and a drastic reduction in peat accumulation under the drier uplifted surface conditions. The permafrost dynamics (aggradation, frost-heave and thaw) ushered changes in plant assemblages and carbon accumulation, and consequently in the biomarker trends too. Detailed biomarker analyses indicate abundant neutral lipids, which follow the general pattern: n-alkanols > sterols ≥ n-alkanes ≥ triterpenols. The lignin monomers are not as abundant as the lipids and increase with depth. The selected aliphatic and phenolic compounds are source specific, and they have different degrees of lability, which is useful for tracing the impact of permafrost dynamics (peat accumulation and/or decay associated with thawing). However, common interpretation of biomarker patterns, and perceived hydrological and climate changes, must be applied carefully in permafrost regions. The increased proportion (selective preservation) of n-alkanes and lignin is a robust indicator of cumulative decomposition trajectories, which is mirrored by functional compounds (e.g. n-alkanol, triterpenol, and sterol concentrations) showing opposite trends. The distribution of these compounds follows first order decay kinetics, and concurs with the downcore diagenetic changes. In particular, some of the biomarker ratios (e.g. stanol/sterol and higher plant alkane index) seem promising for tracing SOC decomposition despite changes in botanical imprint, and sites spanning across different soil types and locations. Carbon accumulation rate calculated at these sites varies from 18.1 to 31.1 gC m− 2 yr− 1, and it's evident selective preservation, molecular complexity of organic compounds, and freezing conditions enhance the long-term stability of SOC. Further, our results suggest that permafrost dynamics strongly impact the more undecomposed SOC that could be rapidly remobilized through ongoing thermokarst expansion.\n
\n\n\n\n \n\n \n \n \n \n \n Concurrent biotic interactions influence plant performance at their altitudinal distribution margins.\n \n \n \n\n\n \n Kaarlejarvi, E.; and Olofsson, J.\n\n\n \n\n\n\n Oikos, 123(8): 943–952. August 2014.\n 00006\n\n\n\n
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\n\n\n@article{kaarlejarvi_concurrent_2014,\n\ttitle = {Concurrent biotic interactions influence plant performance at their altitudinal distribution margins},\n\tvolume = {123},\n\tissn = {0030-1299},\n\tdoi = {10.1111/oik.01261},\n\tabstract = {Recent studies have shown that biotic interactions can shape species' distributions, but empirical data on multiple biotic interactions are scarce. Therefore, we examined effects of plant-plant and plant-herbivore interactions on plant survival, growth and reproduction at different altitudes. For these purposes we conducted a factorial neighbor removal and large herbivore exclusion experiment with six transplant species (three tall forbs with their main distribution at low altitudes and three small forbs with their main distribution at high altitudes) on Laktacohkka Mountain, northern Sweden, replicated at two altitudes (ca 600 and 900 m a.s.l.) and consequently a 2.1 degrees C difference in summer air temperatures. Overall transplant survival was 93\\%. Two out of three tall forbs grew better at low than at high altitudes, while no significant differences in growth between altitudes were found for any of the three small forbs. Since the main difference in abiotic conditions between the altitudes was most likely in temperature (as the sites were topographically and edaphically matched as closely as possible), this result indicates that climatic warming could induce upward migration of tall low-altitude forbs. Negative plant-plant interactions prevailed at both altitudes, and we found indications that competition may set the lower altitudinal limits of some small tundra forbs. Thus, increased competition in response to climate warming may potentially shift the lower margins of high-altitude forbs' distributions upward. Large mammalian grazers reduced the growth of tall forbs and enhanced the flowering of small forbs, and grazers could thus at least partly counteract the anticipated warming-induced distribution shifts.},\n\tlanguage = {English},\n\tnumber = {8},\n\tjournal = {Oikos},\n\tauthor = {Kaarlejarvi, Elina and Olofsson, Johan},\n\tmonth = aug,\n\tyear = {2014},\n\tnote = {00006},\n\tkeywords = {\\#nosource, Alpine plants, arctic tundra, community responses, competition, ecology, environmental-changes, facilitation, positive interactions, recent climate-change, stress},\n\tpages = {943--952},\n}\n\n\n\n\n\n Recent studies have shown that biotic interactions can shape species' distributions, but empirical data on multiple biotic interactions are scarce. Therefore, we examined effects of plant-plant and plant-herbivore interactions on plant survival, growth and reproduction at different altitudes. For these purposes we conducted a factorial neighbor removal and large herbivore exclusion experiment with six transplant species (three tall forbs with their main distribution at low altitudes and three small forbs with their main distribution at high altitudes) on Laktacohkka Mountain, northern Sweden, replicated at two altitudes (ca 600 and 900 m a.s.l.) and consequently a 2.1 degrees C difference in summer air temperatures. Overall transplant survival was 93%. Two out of three tall forbs grew better at low than at high altitudes, while no significant differences in growth between altitudes were found for any of the three small forbs. Since the main difference in abiotic conditions between the altitudes was most likely in temperature (as the sites were topographically and edaphically matched as closely as possible), this result indicates that climatic warming could induce upward migration of tall low-altitude forbs. Negative plant-plant interactions prevailed at both altitudes, and we found indications that competition may set the lower altitudinal limits of some small tundra forbs. Thus, increased competition in response to climate warming may potentially shift the lower margins of high-altitude forbs' distributions upward. Large mammalian grazers reduced the growth of tall forbs and enhanced the flowering of small forbs, and grazers could thus at least partly counteract the anticipated warming-induced distribution shifts.\n
\n\n\n\n \n\n \n \n \n \n \n Biogeochemical variability during the past 3.6 million years recorded by FTIR spectroscopy in the sediment record of Lake El'gygytgyn, Far East Russian Arctic.\n \n \n \n\n\n \n Meyer-Jacob, C.; Vogel, H.; Gebhardt, A. C.; Wennrich, V.; Melles, M.; and Rosén, P.\n\n\n \n\n\n\n Climate of the Past, 10(1): 209–220. 2014.\n 00006\n\n\n\n
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\n\n\n@article{meyer-jacob_biogeochemical_2014,\n\ttitle = {Biogeochemical variability during the past 3.6 million years recorded by {FTIR} spectroscopy in the sediment record of {Lake} {El}'gygytgyn, {Far} {East} {Russian} {Arctic}},\n\tvolume = {10},\n\tissn = {1814-9324},\n\tdoi = {10.5194/cp-10-209-2014},\n\tabstract = {A number of studies have shown that Fourier transform infrared spectroscopy (FTIRS) can be applied to quantitatively assess lacustrine sediment constituents. In this study, we developed calibration models based on FTIRS for the quantitative determination of biogenic silica (BSi; n = 420; gradient: 0.9-56.5 \\%), total organic carbon (TOC; n = 309; gradient: 0-2.9 \\%), and total inorganic carbon (TIC; n = 152; gradient: 0-0.4 \\%) in a 318 m-long sediment record with a basal age of 3.6 million years from Lake El'gygytgyn, Far East Russian Arctic. The developed partial least squares (PLS) regression models yield high cross-validated (CV) R-CV(2) = 0.86-0.91 and low root mean square error of cross-validation (RMSECV) (3.1-7.0\\% of the gradient for the different properties). By applying these models to 6771 samples from the entire sediment record, we obtained detailed insight into bioproductivity variations in Lake El'gygytgyn throughout the middle to late Pliocene and Quaternary. High accumulation rates of BSi indicate a productivity maximum during the middle Pliocene (3.6-3.3 Ma), followed by gradually decreasing rates during the late Pliocene and Quaternary. The average BSi accumulation during the middle Pliocene was similar to 3 times higher than maximum accumulation rates during the past 1.5 million years. The indicated progressive deterioration of environmental and climatic conditions in the Siberian Arctic starting at ca. 3.3 Ma is consistent with the first occurrence of glacial periods and the finally complete establishment of glacial-interglacial cycles during the Quaternary.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Climate of the Past},\n\tauthor = {Meyer-Jacob, C. and Vogel, H. and Gebhardt, A. C. and Wennrich, V. and Melles, M. and Rosén, P.},\n\tyear = {2014},\n\tnote = {00006},\n\tkeywords = {\\#nosource, Geochemistry, biogenic silica, carbonate, humic substances, indicator, ne russia, oxygen isotopes, pliocene sea-level, spectra, transform infrared-spectroscopy},\n\tpages = {209--220},\n}\n\n\n\n\n\n A number of studies have shown that Fourier transform infrared spectroscopy (FTIRS) can be applied to quantitatively assess lacustrine sediment constituents. In this study, we developed calibration models based on FTIRS for the quantitative determination of biogenic silica (BSi; n = 420; gradient: 0.9-56.5 %), total organic carbon (TOC; n = 309; gradient: 0-2.9 %), and total inorganic carbon (TIC; n = 152; gradient: 0-0.4 %) in a 318 m-long sediment record with a basal age of 3.6 million years from Lake El'gygytgyn, Far East Russian Arctic. The developed partial least squares (PLS) regression models yield high cross-validated (CV) R-CV(2) = 0.86-0.91 and low root mean square error of cross-validation (RMSECV) (3.1-7.0% of the gradient for the different properties). By applying these models to 6771 samples from the entire sediment record, we obtained detailed insight into bioproductivity variations in Lake El'gygytgyn throughout the middle to late Pliocene and Quaternary. High accumulation rates of BSi indicate a productivity maximum during the middle Pliocene (3.6-3.3 Ma), followed by gradually decreasing rates during the late Pliocene and Quaternary. The average BSi accumulation during the middle Pliocene was similar to 3 times higher than maximum accumulation rates during the past 1.5 million years. The indicated progressive deterioration of environmental and climatic conditions in the Siberian Arctic starting at ca. 3.3 Ma is consistent with the first occurrence of glacial periods and the finally complete establishment of glacial-interglacial cycles during the Quaternary.\n
\n\n\n\n \n\n \n \n \n \n \n Catchment-scale dissolved carbon concentrations and export estimates across six subarctic streams in northern Sweden.\n \n \n \n\n\n \n Giesler, R.; Lyon, S. W.; Morth, C.; Karlsson, J.; Karlsson, E. M.; Jantze, E. J.; Destouni, G.; and Humborg, C.\n\n\n \n\n\n\n Biogeosciences, 11(2): 525–537. 2014.\n 00015\n\n\n\n
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\n\n\n@article{giesler_catchment-scale_2014,\n\ttitle = {Catchment-scale dissolved carbon concentrations and export estimates across six subarctic streams in northern {Sweden}},\n\tvolume = {11},\n\tissn = {1726-4170},\n\tdoi = {10.5194/bg-11-525-2014},\n\tabstract = {Climatic change is currently enhancing permafrost thawing and the flow of water through the landscape in subarctic and arctic catchments, with major consequences for the carbon export to aquatic ecosystems. We studied stream water carbon export in several tundra-dominated catchments in northern Sweden. There were clear seasonal differences in both dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) concentrations. The highest DOC concentrations occurred during the spring freshet while the highest DIC concentrations were always observed during winter baseflow conditions for the six catchments considered in this study. Long-term trends for the period 1982 to 2010 for one of the streams showed that DIC concentrations has increased by 9\\% during the 28 yr of measurement while no clear trend was found for DOC. Similar increasing trends were also found for conductivity, Ca and Mg. When trends were discretized into individual months, we found a significant linear increase in DIC concentrations with time for September, November and December. In these subarctic catchments, the annual mass of C exported as DIC was in the same order of magnitude as DOC; the average proportion of DIC to the total dissolved C exported was 61\\% for the six streams. Furthermore, there was a direct relationship between total runoff and annual dissolved carbon fluxes for these six catchments. These relationships were more prevalent for annual DIC exports than annual DOC exports in this region. Our results also highlight that both DOC and DIC can be important in high-latitude ecosystems. This is particularly relevant in environments where thawing permafrost and changes to subsurface ice due to global warming can influence stream water fluxes of C. The large proportion of stream water DIC flux also has implications on regional C budgets and needs to be considered in order to understand climate-induced feedback mechanisms across the landscape.},\n\tlanguage = {English},\n\tnumber = {2},\n\tjournal = {Biogeosciences},\n\tauthor = {Giesler, R. and Lyon, S. W. and Morth, C.-M. and Karlsson, J. and Karlsson, E. M. and Jantze, E. J. and Destouni, G. and Humborg, C.},\n\tyear = {2014},\n\tnote = {00015},\n\tkeywords = {\\#nosource, boreal catchments, climate-change, dioxide supersaturation, lakes, organic-carbon, permafrost, release, respiration, river discharge, tundra},\n\tpages = {525--537},\n}\n\n\n\n\n\n Climatic change is currently enhancing permafrost thawing and the flow of water through the landscape in subarctic and arctic catchments, with major consequences for the carbon export to aquatic ecosystems. We studied stream water carbon export in several tundra-dominated catchments in northern Sweden. There were clear seasonal differences in both dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) concentrations. The highest DOC concentrations occurred during the spring freshet while the highest DIC concentrations were always observed during winter baseflow conditions for the six catchments considered in this study. Long-term trends for the period 1982 to 2010 for one of the streams showed that DIC concentrations has increased by 9% during the 28 yr of measurement while no clear trend was found for DOC. Similar increasing trends were also found for conductivity, Ca and Mg. When trends were discretized into individual months, we found a significant linear increase in DIC concentrations with time for September, November and December. In these subarctic catchments, the annual mass of C exported as DIC was in the same order of magnitude as DOC; the average proportion of DIC to the total dissolved C exported was 61% for the six streams. Furthermore, there was a direct relationship between total runoff and annual dissolved carbon fluxes for these six catchments. These relationships were more prevalent for annual DIC exports than annual DOC exports in this region. Our results also highlight that both DOC and DIC can be important in high-latitude ecosystems. This is particularly relevant in environments where thawing permafrost and changes to subsurface ice due to global warming can influence stream water fluxes of C. The large proportion of stream water DIC flux also has implications on regional C budgets and needs to be considered in order to understand climate-induced feedback mechanisms across the landscape.\n
\n\n\n\n \n\n \n \n \n \n \n \n Insensitivity of Soil Microbial Activity to Temporal Variation in Soil N in Subarctic Tundra: Evidence from Responses to Large Migratory Grazers.\n \n \n \n \n\n\n \n Stark, S.; and Väisänen, M.\n\n\n \n\n\n\n Ecosystems, 17(5): 906–917. August 2014.\n \n\n\n\n
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\n\n\n@article{stark_insensitivity_2014,\n\ttitle = {Insensitivity of {Soil} {Microbial} {Activity} to {Temporal} {Variation} in {Soil} {N} in {Subarctic} {Tundra}: {Evidence} from {Responses} to {Large} {Migratory} {Grazers}},\n\tvolume = {17},\n\tissn = {1432-9840, 1435-0629},\n\tshorttitle = {Insensitivity of {Soil} {Microbial} {Activity} to {Temporal} {Variation} in {Soil} {N} in {Subarctic} {Tundra}},\n\turl = {https://link.springer.com/article/10.1007/s10021-014-9768-2},\n\tdoi = {10.1007/s10021-014-9768-2},\n\tabstract = {Large migratory grazers commonly influence soil processes in tundra ecosystems. However, the extent to which grazing effects are limited to intensive grazing periods associated with migration has not previously been investigated. We analyzed seasonal patterns in soil nitrogen (N), microbial respiration and extracellular enzyme activities (EEAs) in a lightly grazed tundra and a heavily grazed tundra that has been subjected to intensive grazing during reindeer (Rangifer tarandus L.) migration for the past 50 years. We hypothesized that due to the fertilizing effect of the reindeer, microbial respiration and EEAs related to microbial C acquisition should be higher in heavily grazed areas compared to lightly grazed areas and that the effects of grazing should be strongest during reindeer migration. Reindeer migration caused a dramatic peak in soil N availability, but in contrast to our predictions, the effect of grazing was more or less constant over the growing season and the seasonal patterns of microbial activities and microbial N were strikingly uniform between the lightly and heavily grazed areas. Microbial respiration and the EEAs of β-glucosidase, acid-phosphatase, and leucine-aminopeptidase were higher, whereas that of N-acetylglucosamidase was lower in the heavily grazed area. Experimental fertilization had no effect on EEAs related to C acquisition at either level of grazing intensity. Our findings suggest that soil microbial activities were independent of grazing-induced temporal variation in soil N availability. Instead, the effect of grazing on soil microbial activities appeared to be mediated by substrate availability for soil microorganisms. Following a shift in the dominant vegetation in response to grazing from dwarf shrubs to graminoids, the effect of grazing on soil processes is no longer sensitive to temporal grazing patterns; rather, grazers exert a consistent positive effect on the soil microbial potential for soil C decomposition.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-05-27},\n\tjournal = {Ecosystems},\n\tauthor = {Stark, Sari and Väisänen, Maria},\n\tmonth = aug,\n\tyear = {2014},\n\tkeywords = {\\#nosource},\n\tpages = {906--917},\n}\n\n\n\n\n\n Large migratory grazers commonly influence soil processes in tundra ecosystems. However, the extent to which grazing effects are limited to intensive grazing periods associated with migration has not previously been investigated. We analyzed seasonal patterns in soil nitrogen (N), microbial respiration and extracellular enzyme activities (EEAs) in a lightly grazed tundra and a heavily grazed tundra that has been subjected to intensive grazing during reindeer (Rangifer tarandus L.) migration for the past 50 years. We hypothesized that due to the fertilizing effect of the reindeer, microbial respiration and EEAs related to microbial C acquisition should be higher in heavily grazed areas compared to lightly grazed areas and that the effects of grazing should be strongest during reindeer migration. Reindeer migration caused a dramatic peak in soil N availability, but in contrast to our predictions, the effect of grazing was more or less constant over the growing season and the seasonal patterns of microbial activities and microbial N were strikingly uniform between the lightly and heavily grazed areas. Microbial respiration and the EEAs of β-glucosidase, acid-phosphatase, and leucine-aminopeptidase were higher, whereas that of N-acetylglucosamidase was lower in the heavily grazed area. Experimental fertilization had no effect on EEAs related to C acquisition at either level of grazing intensity. Our findings suggest that soil microbial activities were independent of grazing-induced temporal variation in soil N availability. Instead, the effect of grazing on soil microbial activities appeared to be mediated by substrate availability for soil microorganisms. Following a shift in the dominant vegetation in response to grazing from dwarf shrubs to graminoids, the effect of grazing on soil processes is no longer sensitive to temporal grazing patterns; rather, grazers exert a consistent positive effect on the soil microbial potential for soil C decomposition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Alien Roadside Species More Easily Invade Alpine than Lowland Plant Communities in a Subarctic Mountain Ecosystem.\n \n \n \n \n\n\n \n Lembrechts, J. J.; Milbau, A.; and Nijs, I.\n\n\n \n\n\n\n PLoS ONE, 9(2): e89664. February 2014.\n \n\n\n\n
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\n\n\n@article{lembrechts_alien_2014,\n\ttitle = {Alien {Roadside} {Species} {More} {Easily} {Invade} {Alpine} than {Lowland} {Plant} {Communities} in a {Subarctic} {Mountain} {Ecosystem}},\n\tvolume = {9},\n\tissn = {1932-6203},\n\turl = {http://dx.plos.org/10.1371/journal.pone.0089664},\n\tdoi = {10.1371/journal.pone.0089664},\n\tabstract = {Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.},\n\tnumber = {2},\n\turldate = {2014-03-04},\n\tjournal = {PLoS ONE},\n\tauthor = {Lembrechts, Jonas J. and Milbau, Ann and Nijs, Ivan},\n\teditor = {Moora, Mari},\n\tmonth = feb,\n\tyear = {2014},\n\tkeywords = {\\#nosource},\n\tpages = {e89664},\n}\n\n\n\n\n\n Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.\n
\n\n\n\n \n\n \n \n \n \n \n \n Incorporation of radiometric tracers in peat and implications for estimating accumulation rates.\n \n \n \n \n\n\n \n Hansson, S. V.; Kaste, J. M.; Olid, C.; and Bindler, R.\n\n\n \n\n\n\n Science of The Total Environment, 493: 170–177. September 2014.\n 00007\n\n\n\n
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\n\n\n@article{hansson_incorporation_2014,\n\ttitle = {Incorporation of radiometric tracers in peat and implications for estimating accumulation rates},\n\tvolume = {493},\n\tissn = {0048-9697},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0048969714007682},\n\tdoi = {10.1016/j.scitotenv.2014.05.088},\n\tabstract = {Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides 210Pb, 137Cs, 241Am, and 7Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of 7Be down to 18–20 cm for some cores, and the broad vertical distribution of 241Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age–depth model leads to unrealistic peat mass accumulation rates (400–600 g m− 2 yr− 1), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of 210Pb through the uppermost peat layers, recent peat accumulation rates (200–300 g m− 2 yr− 1) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using 7Be, and if this information is incorporated into age–depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.},\n\turldate = {2017-04-28},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Hansson, Sophia V. and Kaste, James M. and Olid, Carolina and Bindler, Richard},\n\tmonth = sep,\n\tyear = {2014},\n\tnote = {00007},\n\tkeywords = {\\#nosource, Beryllium, Downwash, Lead, Peat accumulation, mercury},\n\tpages = {170--177},\n}\n\n\n\n\n\n Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides 210Pb, 137Cs, 241Am, and 7Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of 7Be down to 18–20 cm for some cores, and the broad vertical distribution of 241Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age–depth model leads to unrealistic peat mass accumulation rates (400–600 g m− 2 yr− 1), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of 210Pb through the uppermost peat layers, recent peat accumulation rates (200–300 g m− 2 yr− 1) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using 7Be, and if this information is incorporated into age–depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.\n
\n\n\n\n \n\n \n \n \n \n \n \n Monte Carlo uncertainty calculation of 210Pb chronologies and accumulation rates of sediments and peat bogs.\n \n \n \n \n\n\n \n Sanchez-Cabeza, J.; Ruiz-Fernández, A. C.; Ontiveros-Cuadras, J. F.; Pérez Bernal, L. H.; and Olid, C.\n\n\n \n\n\n\n Quaternary Geochronology, 23: 80–93. October 2014.\n 00018\n\n\n\n
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\n\n\n@article{sanchez-cabeza_monte_2014,\n\ttitle = {Monte {Carlo} uncertainty calculation of {210Pb} chronologies and accumulation rates of sediments and peat bogs},\n\tvolume = {23},\n\tissn = {1871-1014},\n\turl = {http://www.sciencedirect.com/science/article/pii/S1871101414000569},\n\tdoi = {10.1016/j.quageo.2014.06.002},\n\tabstract = {210Pb dating is a key technique to study sedimentary records of environmental change in the Anthropocene over a time scale of 100–150 years. Uncertainty estimation of 210Pb ages and accumulation rates, when provided by the authors, are usually based on quadratic propagation of uncertainties. In this work, we describe the use of Monte Carlo simulation to estimate 210Pb dating uncertainties in sediment and peat cores. The methodology allows, by using nowadays common computers, the assessment of 210Pb dating uncertainties in a simple manner, using readily-accessible computers and widely-used proprietary spreadsheet software, and avoiding the derivation of rather complex formulae. Results were calculated and compared with quadratic propagation uncertainties in a marine, lacustrine and peat bog core. The analysis of the uncertainty budgets indicated that, overall, the total and unsupported (or base) 210Pb concentrations are the largest contributors to uncertainty, as well as the layer depths when sediment accumulation rates were calculated. Beyond 210Pb dating, the Monte Carlo scheme described here could be used in any field of the analytical sciences, including other radiochronological applications.},\n\turldate = {2017-04-28},\n\tjournal = {Quaternary Geochronology},\n\tauthor = {Sanchez-Cabeza, Joan-Albert and Ruiz-Fernández, Ana Carolina and Ontiveros-Cuadras, Jorge Feliciano and Pérez Bernal, Libia Hascibe and Olid, Carolina},\n\tmonth = oct,\n\tyear = {2014},\n\tnote = {00018},\n\tkeywords = {\\#nosource, 210Pb dating, Monte Carlo statistics, Peat bog core, Sediment core, Uncertainty},\n\tpages = {80--93},\n}\n\n\n\n\n\n 210Pb dating is a key technique to study sedimentary records of environmental change in the Anthropocene over a time scale of 100–150 years. Uncertainty estimation of 210Pb ages and accumulation rates, when provided by the authors, are usually based on quadratic propagation of uncertainties. In this work, we describe the use of Monte Carlo simulation to estimate 210Pb dating uncertainties in sediment and peat cores. The methodology allows, by using nowadays common computers, the assessment of 210Pb dating uncertainties in a simple manner, using readily-accessible computers and widely-used proprietary spreadsheet software, and avoiding the derivation of rather complex formulae. Results were calculated and compared with quadratic propagation uncertainties in a marine, lacustrine and peat bog core. The analysis of the uncertainty budgets indicated that, overall, the total and unsupported (or base) 210Pb concentrations are the largest contributors to uncertainty, as well as the layer depths when sediment accumulation rates were calculated. Beyond 210Pb dating, the Monte Carlo scheme described here could be used in any field of the analytical sciences, including other radiochronological applications.\n
\n\n\n\n \n\n \n \n \n \n \n \n Autochthonous resources are the main driver of consumer production in dystrophic boreal lakes.\n \n \n \n \n\n\n \n Lau, D. C. P.; Sundh, I.; Vrede, T.; Pickova, J.; and Goedkoop, W.\n\n\n \n\n\n\n Ecology, 95(6): 1506–1519. June 2014.\n 00027\n\n\n\n
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\n\n\n@article{lau_autochthonous_2014,\n\ttitle = {Autochthonous resources are the main driver of consumer production in dystrophic boreal lakes},\n\tvolume = {95},\n\tissn = {1939-9170},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1890/13-1141.1/abstract},\n\tdoi = {10.1890/13-1141.1},\n\tabstract = {Dystrophic lakes are widespread in temperate regions and intimately interact with surrounding terrestrial ecosystems in energy and nutrient dynamics, yet the relative importance of autochthonous and allochthonous resources to consumer production in dystrophic lakes remains controversial. We argue that allochthonous organic matter quantitatively dominates over photosynthetic autotrophs in dystrophic lakes, but that autotrophs are higher in diet quality and more important for consumers as they contain essential polyunsaturated fatty acids (PUFA). In a field study, we tested the hypotheses that (1) autochthonous primary production is the main driver for consumer production, despite being limited by light availability and low nutrient supplies, and greater supply of allochthonous carbon, (2) the relative contribution of autotrophs to consumers is directly related to their tissue PUFA concentrations, and (3) methane-oxidizing bacteria (MOB) provide an energy alternative for consumers. Pelagic and benthic consumer taxa representing different trophic levels were sampled from five dystrophic lakes: isopod Asellus aquaticus, megalopteran Sialis lutaria, dipteran Chaoborus flavicans, and perch Perca fluviatilis. Based on carbon and nitrogen stable isotopes, the relative contributions of autochthonous (biofilms and seston) and allochthonous (coarse particulate and dissolved organic matter) resources and MOB to these taxa were 47–79\\%, 9–44\\% and 7–12\\% respectively. Results from fatty acid (FA) analyses show that the relative ω3-FA and PUFA concentrations increased with trophic level (Asellus {\\textless} Sialis and Chaoborus {\\textless} Perca). Also, eicosapentaenoic-acid (EPA), ω3-FA and PUFA concentrations increased with the autochthonous contribution in consumers, i.e., a 47–79\\% biofilm and/or seston diet resulted in tissue EPA of 4.2–18.4, ω3 FAs of 11.6–37.0 and PUFA of 21.6–61.0 mg/g dry mass. The results indicate that consumers in dystrophic lakes predominantly rely on energy from autotrophs and that their PUFA concentrations are dependent on the relative contribution of these autochthonous resources. The limited energy support from MOB suggests they are not negligible and are potentially an integral part of the food webs. Our findings show that autochthonous resources are the main driver of secondary production even in dystrophic lakes and offer new insights into the functioning of these ecosystems.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-05-27},\n\tjournal = {Ecology},\n\tauthor = {Lau, Danny C. P. and Sundh, Ingvar and Vrede, Tobias and Pickova, Jana and Goedkoop, Willem},\n\tmonth = jun,\n\tyear = {2014},\n\tnote = {00027},\n\tkeywords = {\\#nosource, Algae, Fatty acids, IsoSource, SIAR, Trophic transfer, aquatic food webs, fish, invertebrates, stable isotopes},\n\tpages = {1506--1519},\n}\n\n\n\n\n\n Dystrophic lakes are widespread in temperate regions and intimately interact with surrounding terrestrial ecosystems in energy and nutrient dynamics, yet the relative importance of autochthonous and allochthonous resources to consumer production in dystrophic lakes remains controversial. We argue that allochthonous organic matter quantitatively dominates over photosynthetic autotrophs in dystrophic lakes, but that autotrophs are higher in diet quality and more important for consumers as they contain essential polyunsaturated fatty acids (PUFA). In a field study, we tested the hypotheses that (1) autochthonous primary production is the main driver for consumer production, despite being limited by light availability and low nutrient supplies, and greater supply of allochthonous carbon, (2) the relative contribution of autotrophs to consumers is directly related to their tissue PUFA concentrations, and (3) methane-oxidizing bacteria (MOB) provide an energy alternative for consumers. Pelagic and benthic consumer taxa representing different trophic levels were sampled from five dystrophic lakes: isopod Asellus aquaticus, megalopteran Sialis lutaria, dipteran Chaoborus flavicans, and perch Perca fluviatilis. Based on carbon and nitrogen stable isotopes, the relative contributions of autochthonous (biofilms and seston) and allochthonous (coarse particulate and dissolved organic matter) resources and MOB to these taxa were 47–79%, 9–44% and 7–12% respectively. Results from fatty acid (FA) analyses show that the relative ω3-FA and PUFA concentrations increased with trophic level (Asellus \\textless Sialis and Chaoborus \\textless Perca). Also, eicosapentaenoic-acid (EPA), ω3-FA and PUFA concentrations increased with the autochthonous contribution in consumers, i.e., a 47–79% biofilm and/or seston diet resulted in tissue EPA of 4.2–18.4, ω3 FAs of 11.6–37.0 and PUFA of 21.6–61.0 mg/g dry mass. The results indicate that consumers in dystrophic lakes predominantly rely on energy from autotrophs and that their PUFA concentrations are dependent on the relative contribution of these autochthonous resources. The limited energy support from MOB suggests they are not negligible and are potentially an integral part of the food webs. Our findings show that autochthonous resources are the main driver of secondary production even in dystrophic lakes and offer new insights into the functioning of these ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Bioavailable Soil Phosphorus Decreases with Increasing Elevation in a Subarctic Tundra Landscape.\n \n \n \n \n\n\n \n Vincent, A. G.; Sundqvist, M. K.; Wardle, D. A.; and Giesler, R.\n\n\n \n\n\n\n PLOS ONE, 9(3): e92942. March 2014.\n \n\n\n\n
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\n\n\n@article{vincent_bioavailable_2014,\n\ttitle = {Bioavailable {Soil} {Phosphorus} {Decreases} with {Increasing} {Elevation} in a {Subarctic} {Tundra} {Landscape}},\n\tvolume = {9},\n\tissn = {1932-6203},\n\turl = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092942},\n\tdoi = {10.1371/journal.pone.0092942},\n\tabstract = {Phosphorus (P) is an important macronutrient in arctic and subarctic tundra and its bioavailability is regulated by the mineralization of organic P. Temperature is likely to be an important control on P bioavailability, although effects may differ across contrasting plant communities with different soil properties. We used an elevational gradient in northern Sweden that included both heath and meadow vegetation types at all elevations to study the effects of temperature, soil P sorption capacity and oxalate-extractable aluminium (Alox) and iron (Feox) on the concentration of different soil P fractions. We hypothesized that the concentration of labile P fractions would decrease with increasing elevation (and thus declining temperature), but would be lower in meadow than in heath, given that N to P ratios in meadow foliage are higher. As expected, labile P in the form of Resin-P declined sharply with elevation for both vegetation types. Meadow soils did not have lower concentrations of Resin-P than heath soils, but they did have 2–fold and 1.5–fold higher concentrations of NaOH-extractable organic P and Residual P, respectively. Further, meadow soils had 3-fold higher concentrations of Alox + Feox and a 20\\% higher P sorption index than did heath soils. Additionally, Resin-P expressed as a proportion of total soil P for the meadow was on average half that in the heath. Declining Resin-P concentrations with elevation were best explained by an associated 2.5–3.0°C decline in temperature. In contrast, the lower P availability in meadow relative to heath soils may be associated with impaired organic P mineralization, as indicated by a higher accumulation of organic P and P sorption capacity. Our results indicate that predicted temperature increases in the arctic over the next century may influence P availability and biogeochemistry, with consequences for key ecosystem processes limited by P, such as primary productivity.},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {PLOS ONE},\n\tauthor = {Vincent, Andrea G. and Sundqvist, Maja K. and Wardle, David A. and Giesler, Reiner},\n\tmonth = mar,\n\tyear = {2014},\n\tkeywords = {\\#nosource, Aluminum, Analysis of variance, Biogeochemistry, Ecosystems, Soil ecology, Sorption, fractionation, tundra},\n\tpages = {e92942},\n}\n\n\n\n\n\n Phosphorus (P) is an important macronutrient in arctic and subarctic tundra and its bioavailability is regulated by the mineralization of organic P. Temperature is likely to be an important control on P bioavailability, although effects may differ across contrasting plant communities with different soil properties. We used an elevational gradient in northern Sweden that included both heath and meadow vegetation types at all elevations to study the effects of temperature, soil P sorption capacity and oxalate-extractable aluminium (Alox) and iron (Feox) on the concentration of different soil P fractions. We hypothesized that the concentration of labile P fractions would decrease with increasing elevation (and thus declining temperature), but would be lower in meadow than in heath, given that N to P ratios in meadow foliage are higher. As expected, labile P in the form of Resin-P declined sharply with elevation for both vegetation types. Meadow soils did not have lower concentrations of Resin-P than heath soils, but they did have 2–fold and 1.5–fold higher concentrations of NaOH-extractable organic P and Residual P, respectively. Further, meadow soils had 3-fold higher concentrations of Alox + Feox and a 20% higher P sorption index than did heath soils. Additionally, Resin-P expressed as a proportion of total soil P for the meadow was on average half that in the heath. Declining Resin-P concentrations with elevation were best explained by an associated 2.5–3.0°C decline in temperature. In contrast, the lower P availability in meadow relative to heath soils may be associated with impaired organic P mineralization, as indicated by a higher accumulation of organic P and P sorption capacity. Our results indicate that predicted temperature increases in the arctic over the next century may influence P availability and biogeochemistry, with consequences for key ecosystem processes limited by P, such as primary productivity.\n
\n\n\n\n \n\n \n \n \n \n \n \n Below-ground opportunities in vegetation science.\n \n \n \n \n\n\n \n Wilson, S. D.\n\n\n \n\n\n\n Journal of Vegetation Science, 25(5): 1117–1125. September 2014.\n \n\n\n\n
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\n\n\n@article{wilson_below-ground_2014,\n\ttitle = {Below-ground opportunities in vegetation science},\n\tvolume = {25},\n\tissn = {1654-1103},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/jvs.12168/abstract},\n\tdoi = {10.1111/jvs.12168},\n\tabstract = {Background\n\nThe below-ground component of vegetation accounts for the bulk of plant mass and vegetation function (e.g. carbon sequestration) in temperate ecosystems, yet the proportion of plant ecology studies that consider roots is {\\textless}20\\%.\n\n\nMethods\n\nI review how minirhizotron technology and DNA sequencing of mixed-species root samples allows new insights into below-ground vegetation structure and function.\n\n\nResults\n\nRecent advances highlight important differences between the below- and above-ground parts of vegetation. For example, plant species richness below ground is about 50\\% greater than that above ground. Below-ground plant richness has been measured from only a few sites, and patterns along gradients of productivity and life-form turnover are unknown. Fine roots differ from leaves in temperate ecosystems by having a growing season 40\\% longer, and by persisting over multiple growing seasons. Aspects of roots other than growth may vary seasonally, such as nutrient uptake, competition with microbes, or mycorrhizal hyphal production or activity. Minirhizotrons allow the investigation of root heterogeneity at very small scales ({\\textless}1 mm) that may be more relevant to fine roots and rhizospheres than data obtained from larger-scale soil sampling.\n\n\nConclusions\n\nWork in the near future promises a more complete picture of vegetation function by elucidating mechanisms within the bulk of vegetation, below ground.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Wilson, Scott D.},\n\tmonth = sep,\n\tyear = {2014},\n\tkeywords = {\\#nosource, Heterogeneity, Production, Root, diversity, invasion, phenology, species richness},\n\tpages = {1117--1125},\n}\n\n\n\n\n\n Background The below-ground component of vegetation accounts for the bulk of plant mass and vegetation function (e.g. carbon sequestration) in temperate ecosystems, yet the proportion of plant ecology studies that consider roots is \\textless20%. Methods I review how minirhizotron technology and DNA sequencing of mixed-species root samples allows new insights into below-ground vegetation structure and function. Results Recent advances highlight important differences between the below- and above-ground parts of vegetation. For example, plant species richness below ground is about 50% greater than that above ground. Below-ground plant richness has been measured from only a few sites, and patterns along gradients of productivity and life-form turnover are unknown. Fine roots differ from leaves in temperate ecosystems by having a growing season 40% longer, and by persisting over multiple growing seasons. Aspects of roots other than growth may vary seasonally, such as nutrient uptake, competition with microbes, or mycorrhizal hyphal production or activity. Minirhizotrons allow the investigation of root heterogeneity at very small scales (\\textless1 mm) that may be more relevant to fine roots and rhizospheres than data obtained from larger-scale soil sampling. Conclusions Work in the near future promises a more complete picture of vegetation function by elucidating mechanisms within the bulk of vegetation, below ground.\n
\n\n\n\n \n\n \n \n \n \n \n \n Snow cover consistently affects growth and reproduction of Empetrum hermaphroditum across latitudinal and local climatic gradients.\n \n \n \n \n\n\n \n Bienau, M. J.; Hattermann, D.; Kröncke, M.; Kretz, L.; Otte, A.; Eiserhardt, W. L.; Milbau, A.; Graae, B. J.; Durka, W.; and Eckstein, R. L.\n\n\n \n\n\n\n Alpine Botany, 124(2): 115–129. October 2014.\n \n\n\n\n
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\n\n\n@article{bienau_snow_2014,\n\ttitle = {Snow cover consistently affects growth and reproduction of {Empetrum} hermaphroditum across latitudinal and local climatic gradients},\n\tvolume = {124},\n\tissn = {1664-2201, 1664-221X},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1007/s00035-014-0137-8},\n\tdoi = {10.1007/s00035-014-0137-8},\n\tabstract = {Arctic ecosystems face strong changes in snow conditions due to global warming. In contrast to habitat specialists, species occupying a wide range of microhabitats under different snow conditions may better cope with such changes. We studied how growth and reproduction of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitat types differing in winter snow depth and summer irradiation, and whether the observed patterns were consistent along a local climatic gradient (sub-continental vs. sub-oceanic climates) and along a latitudinal gradient (northern Sweden vs. central Norway). Habitat type explained most of the variation in growth and reproduction. Shoots from shallow snow cover and high summer irradiation habitats had higher numbers of flowers and fruits, lower ramet heights, shorter shoot segments, lower numbers of lateral shoots and total biomass but higher leaf density and higher relative leaf allocation than shoots from habitats with higher snow depth and lower summer irradiation. In addition, biomass, leaf allocation and leaf life expectancy were strongly affected by latitude, whereas local climate had strong effects on seed number and seed mass. Empetrum showed high phenotypic trait variation, with a consistent match between local habitat conditions and its growth and reproduction. Although study areas varied strongly with respect to latitude and local climatic conditions, response patterns of growth and reproduction to habitats with different environmental conditions were consistent. Large elasticity of traits suggests that Empetrum may have the potential to cope with changing snow conditions expected in the course of climate change.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2016-11-08},\n\tjournal = {Alpine Botany},\n\tauthor = {Bienau, Miriam J. and Hattermann, Dirk and Kröncke, Michael and Kretz, Lena and Otte, Annette and Eiserhardt, Wolf L. and Milbau, Ann and Graae, Bente J. and Durka, Walter and Eckstein, R. Lutz},\n\tmonth = oct,\n\tyear = {2014},\n\tkeywords = {\\#nosource},\n\tpages = {115--129},\n}\n\n\n\n\n\n Arctic ecosystems face strong changes in snow conditions due to global warming. In contrast to habitat specialists, species occupying a wide range of microhabitats under different snow conditions may better cope with such changes. We studied how growth and reproduction of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitat types differing in winter snow depth and summer irradiation, and whether the observed patterns were consistent along a local climatic gradient (sub-continental vs. sub-oceanic climates) and along a latitudinal gradient (northern Sweden vs. central Norway). Habitat type explained most of the variation in growth and reproduction. Shoots from shallow snow cover and high summer irradiation habitats had higher numbers of flowers and fruits, lower ramet heights, shorter shoot segments, lower numbers of lateral shoots and total biomass but higher leaf density and higher relative leaf allocation than shoots from habitats with higher snow depth and lower summer irradiation. In addition, biomass, leaf allocation and leaf life expectancy were strongly affected by latitude, whereas local climate had strong effects on seed number and seed mass. Empetrum showed high phenotypic trait variation, with a consistent match between local habitat conditions and its growth and reproduction. Although study areas varied strongly with respect to latitude and local climatic conditions, response patterns of growth and reproduction to habitats with different environmental conditions were consistent. Large elasticity of traits suggests that Empetrum may have the potential to cope with changing snow conditions expected in the course of climate change.\n
\n\n\n\n \n\n \n \n \n \n \n Upscaling carbon dioxide emissions from lakes.\n \n \n \n\n\n \n Seekell, D. A.; Carr, J. A.; Gudasz, C.; and Karlsson, J.\n\n\n \n\n\n\n Geophysical Research Letters, 41(21): 7555–7559. November 2014.\n \n\n\n\n
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\n\n\n@article{seekell_upscaling_2014,\n\ttitle = {Upscaling carbon dioxide emissions from lakes},\n\tvolume = {41},\n\tissn = {0094-8276},\n\tdoi = {10.1002/2014GL061824},\n\tabstract = {Quantifying CO2 fluxes from lakes to the atmosphere is important for balancing regional and global-scale carbon budgets. CO2 emissions are estimated through statistical upscaling procedures that aggregate data from a large number of lakes. However, aggregation can bias flux estimates if the physical and chemical factors determining CO2 exchange between water and the atmosphere are not independent. We evaluated the magnitude of aggregation biases with moment expansions and pCO(2) data from 5140 Swedish lakes. The direction of the aggregation bias depends on lake size; mean flux was overestimated by 4\\% for small lakes (0.01-0.1 km(2)) but underestimated by 13\\% for large lakes (100-1000 km(2)). Simple covariance-based correction factors were generated to adjust for upscaling biases. These correction factors represent an easily interpretable and implemented approach to improving the accuracy of regional and global estimates of lake CO2 emissions.},\n\tlanguage = {English},\n\tnumber = {21},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Seekell, David A. and Carr, Joel A. and Gudasz, Cristian and Karlsson, Jan},\n\tmonth = nov,\n\tyear = {2014},\n\tkeywords = {\\#nosource, budget, cycle, inland waters, land, ponds, reservoirs, size-distribution, surface},\n\tpages = {7555--7559},\n}\n\n\n\n\n\n Quantifying CO2 fluxes from lakes to the atmosphere is important for balancing regional and global-scale carbon budgets. CO2 emissions are estimated through statistical upscaling procedures that aggregate data from a large number of lakes. However, aggregation can bias flux estimates if the physical and chemical factors determining CO2 exchange between water and the atmosphere are not independent. We evaluated the magnitude of aggregation biases with moment expansions and pCO(2) data from 5140 Swedish lakes. The direction of the aggregation bias depends on lake size; mean flux was overestimated by 4% for small lakes (0.01-0.1 km(2)) but underestimated by 13% for large lakes (100-1000 km(2)). Simple covariance-based correction factors were generated to adjust for upscaling biases. These correction factors represent an easily interpretable and implemented approach to improving the accuracy of regional and global estimates of lake CO2 emissions.\n
\n\n\n\n \n\n \n \n \n \n \n Atmospheric deposition of persistent organic pollutants and chemicals of emerging concern at two sites in northern Sweden.\n \n \n \n\n\n \n Newton, S.; Bidleman, T.; Bergknut, M.; Racine, J.; Laudon, H.; Giesler, R.; and Wiberg, K.\n\n\n \n\n\n\n Environmental Science-Processes & Impacts, 16(2): 298–305. February 2014.\n \n\n\n\n
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\n\n\n@article{newton_atmospheric_2014,\n\ttitle = {Atmospheric deposition of persistent organic pollutants and chemicals of emerging concern at two sites in northern {Sweden}},\n\tvolume = {16},\n\tissn = {2050-7887},\n\tdoi = {10.1039/c3em00590a},\n\tabstract = {Bimonthly bulk atmospheric deposition samples (precipitation + dry particle) were taken for one year at an arctic (Abisko, 68 degrees 20' N, 19 degrees 03' E) and a sub-arctic (Krycklan 64 degrees 14' N, 19 degrees 46' E) location in northern Sweden using Amberlite IRA-743 as an absorbent for hydrophobic pollutants. The samples were analyzed by gas chromatography-high resolution mass spectrometry (GC-HRMS) for polychlorinated biphenyls (PCBs), legacy organochlorine pesticides (OCPs = hexachlorocyclohexanes and chlordane-related compounds), polybrominated diphenyl ethers (PBDEs) and emerging chemicals. Higher deposition rates of most compounds were observed at the more northern site despite its receiving less precipitation and being more remote. HCHs and PCBs made up the bulk of the total deposition at both sites. Five emerging chemicals were detected: the current-use pesticides trifluralin and chlorothabnil; and non-BDE flame retardants 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and Dechlorane Plus (DP). A decrease in the fraction of the anti isomer of DP was observed at the arctic site, indicating isomer-selective degradation or isomerization during long range transport. Air parcel back trajectories revealed a greater influence from air originating over the ocean at the more northern site. The differences in these air sources were reflected in higher Sigma HCH to Sigma PCB ratios compared to the more southern site, as HCHs are related to volatilization from the ocean and Abisko is located {\\textless}100 km from the Norwegian coast, while PCBs are emitted from continental sources.},\n\tlanguage = {English},\n\tnumber = {2},\n\tjournal = {Environmental Science-Processes \\& Impacts},\n\tauthor = {Newton, Seth and Bidleman, Terry and Bergknut, Magnus and Racine, Jacinthe and Laudon, Hjalmar and Giesler, Reiner and Wiberg, Karin},\n\tmonth = feb,\n\tyear = {2014},\n\tkeywords = {\\#nosource, baltic sea, bulk deposition, current-use pesticides, dechlorane plus, flame retardants, great-lakes, polybrominated diphenyl ethers, polycyclic aromatic-hydrocarbons, snow, transport},\n\tpages = {298--305},\n}\n\n\n\n\n\n Bimonthly bulk atmospheric deposition samples (precipitation + dry particle) were taken for one year at an arctic (Abisko, 68 degrees 20' N, 19 degrees 03' E) and a sub-arctic (Krycklan 64 degrees 14' N, 19 degrees 46' E) location in northern Sweden using Amberlite IRA-743 as an absorbent for hydrophobic pollutants. The samples were analyzed by gas chromatography-high resolution mass spectrometry (GC-HRMS) for polychlorinated biphenyls (PCBs), legacy organochlorine pesticides (OCPs = hexachlorocyclohexanes and chlordane-related compounds), polybrominated diphenyl ethers (PBDEs) and emerging chemicals. Higher deposition rates of most compounds were observed at the more northern site despite its receiving less precipitation and being more remote. HCHs and PCBs made up the bulk of the total deposition at both sites. Five emerging chemicals were detected: the current-use pesticides trifluralin and chlorothabnil; and non-BDE flame retardants 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and Dechlorane Plus (DP). A decrease in the fraction of the anti isomer of DP was observed at the arctic site, indicating isomer-selective degradation or isomerization during long range transport. Air parcel back trajectories revealed a greater influence from air originating over the ocean at the more northern site. The differences in these air sources were reflected in higher Sigma HCH to Sigma PCB ratios compared to the more southern site, as HCHs are related to volatilization from the ocean and Abisko is located \\textless100 km from the Norwegian coast, while PCBs are emitted from continental sources.\n
\n\n\n\n \n\n \n \n \n \n \n \n Contrasting nitrogen and phosphorus dynamics across an elevational gradient for subarctic tundra heath and meadow vegetation.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Wardle, D. A.; Vincent, A.; and Giesler, R.\n\n\n \n\n\n\n Plant and Soil, 383(1-2): 387–399. October 2014.\n 00003\n\n\n\n
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\n\n\n@article{sundqvist_contrasting_2014,\n\ttitle = {Contrasting nitrogen and phosphorus dynamics across an elevational gradient for subarctic tundra heath and meadow vegetation},\n\tvolume = {383},\n\tissn = {0032-079X, 1573-5036},\n\turl = {http://link.springer.com/article/10.1007/s11104-014-2179-5},\n\tdoi = {10.1007/s11104-014-2179-5},\n\tabstract = {AimsThis study explores soil nutrient cycling processes and microbial properties for two contrasting vegetation types along an elevational gradient in subarctic tundra to improve our understanding of how temperature influences nutrient availability in an ecosystem predicted to be sensitive to global warming.MethodsWe measured total amino acid (Amino-N), mineral nitrogen (N) and phosphorus (P) concentrations, in situ net N and P mineralization, net Amino-N consumption, and microbial biomass C, N and P in both heath and meadow soils across an elevational gradient near Abisko, Sweden.ResultsFor the meadow, NH4+ concentrations and net N mineralization were highest at high elevations and microbial properties showed variable responses; these variables were largely unresponsive to elevation for the heath. Amino-N concentrations sometimes showed a tendency to increase with elevation and net Amino-N consumption was often unresponsive to elevation. Overall, PO4-P concentrations decreased with elevation and net P immobilization mostly occurred at lower elevations; these effects were strongest for the heath.ConclusionsOur results reveal that elevation-associated changes in temperature can have contrasting effects on the cycling of N and P in subarctic soils, and that the strength and direction of these effects depend strongly on dominant vegetation type.},\n\tlanguage = {en},\n\tnumber = {1-2},\n\turldate = {2017-02-07},\n\tjournal = {Plant and Soil},\n\tauthor = {Sundqvist, Maja K. and Wardle, David A. and Vincent, Andrea and Giesler, Reiner},\n\tmonth = oct,\n\tyear = {2014},\n\tnote = {00003},\n\tkeywords = {\\#nosource, Amino acids, Immobilization, Microbial biomass, Mineralization, Nutrient availability, PLANT physiology, Plant Sciences, Soil Science \\& Conservation, ecology, temperature},\n\tpages = {387--399},\n}\n\n\n\n\n\n AimsThis study explores soil nutrient cycling processes and microbial properties for two contrasting vegetation types along an elevational gradient in subarctic tundra to improve our understanding of how temperature influences nutrient availability in an ecosystem predicted to be sensitive to global warming.MethodsWe measured total amino acid (Amino-N), mineral nitrogen (N) and phosphorus (P) concentrations, in situ net N and P mineralization, net Amino-N consumption, and microbial biomass C, N and P in both heath and meadow soils across an elevational gradient near Abisko, Sweden.ResultsFor the meadow, NH4+ concentrations and net N mineralization were highest at high elevations and microbial properties showed variable responses; these variables were largely unresponsive to elevation for the heath. Amino-N concentrations sometimes showed a tendency to increase with elevation and net Amino-N consumption was often unresponsive to elevation. Overall, PO4-P concentrations decreased with elevation and net P immobilization mostly occurred at lower elevations; these effects were strongest for the heath.ConclusionsOur results reveal that elevation-associated changes in temperature can have contrasting effects on the cycling of N and P in subarctic soils, and that the strength and direction of these effects depend strongly on dominant vegetation type.\n
\n\n\n\n \n\n \n \n \n \n \n Burned and devoured-Introduced herbivores, fire, and the endemic flora of the high-elevation ecosystem on La Palma, Canary Islands.\n \n \n \n\n\n \n Irl, S. D. H.; Steinbauer, M. J.; Messinger, J.; Blume-Werry, G.; Palomares-Martinez, A.; Beierkuhnlein, C.; and Jentsch, A.\n\n\n \n\n\n\n Arctic Antarctic and Alpine Research, 46(4): 859–869. November 2014.\n 00010\n\n\n\n
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\n\n\n@article{irl_burned_2014,\n\ttitle = {Burned and devoured-{Introduced} herbivores, fire, and the endemic flora of the high-elevation ecosystem on {La} {Palma}, {Canary} {Islands}},\n\tvolume = {46},\n\tissn = {1523-0430},\n\tdoi = {10.1657/1938-4246-46.4.859},\n\tabstract = {Novel disturbance regimes (e.g., introduced herbivores and fire) are among the major drivers of degradation in island ecosystems. High-elevation ecosystems (HEEs) on islands might be especially vulnerable to these disturbances due to high endemism. Here, data from an 11-year exclosure experiment in the HEE of La Palma (Canary Islands) are presented where mammalian herbivores have been introduced. We investigate the combined effect of herbivory and fire on total species richness, seedling richness, and seedling establishment on the whole system and a subset of highly endangered species (target species). Total species richness, seedling species richness, and seedling establishment decreased with herbivory. Five out of eight target species were exclusively found inside the exclosures indicating the negative impact of introduced herbivores on endemic high elevation flora. Target species were generally affected more negatively by introduced herbivores and were subject to significantly higher browsing pressure, probably owing to their lack of defense strategies. A natural wildfire that occurred six years before data sampling substantially increased total species richness and seedling richness in both herbivory exclosure and reference conditions. We conclude that species composition of the HEE has been severely altered by the introduction of non-native herbivores, even though fire seems to have a positive effect on this system.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Arctic Antarctic and Alpine Research},\n\tauthor = {Irl, Severin D. H. and Steinbauer, Manuel J. and Messinger, Jana and Blume-Werry, Gesche and Palomares-Martinez, Angel and Beierkuhnlein, Carl and Jentsch, Anke},\n\tmonth = nov,\n\tyear = {2014},\n\tnote = {00010},\n\tkeywords = {\\#nosource, Plants, disturbance, driven, mammals, oceanic island, pinus-canariensis, population-dynamics, potential natural vegetation, species richness, tenerife},\n\tpages = {859--869},\n}\n\n\n\n\n\n Novel disturbance regimes (e.g., introduced herbivores and fire) are among the major drivers of degradation in island ecosystems. High-elevation ecosystems (HEEs) on islands might be especially vulnerable to these disturbances due to high endemism. Here, data from an 11-year exclosure experiment in the HEE of La Palma (Canary Islands) are presented where mammalian herbivores have been introduced. We investigate the combined effect of herbivory and fire on total species richness, seedling richness, and seedling establishment on the whole system and a subset of highly endangered species (target species). Total species richness, seedling species richness, and seedling establishment decreased with herbivory. Five out of eight target species were exclusively found inside the exclosures indicating the negative impact of introduced herbivores on endemic high elevation flora. Target species were generally affected more negatively by introduced herbivores and were subject to significantly higher browsing pressure, probably owing to their lack of defense strategies. A natural wildfire that occurred six years before data sampling substantially increased total species richness and seedling richness in both herbivory exclosure and reference conditions. We conclude that species composition of the HEE has been severely altered by the introduction of non-native herbivores, even though fire seems to have a positive effect on this system.\n
\n\n\n\n \n\n \n \n \n \n \n \n Diversity and abundance of aromatic catabolic genes in lake sediments in response to temperature change.\n \n \n \n \n\n\n \n Osman, O. A.; Gudasz, C.; and Bertilsson, S.\n\n\n \n\n\n\n FEMS Microbiology Ecology, 88(3): 468–481. June 2014.\n Publisher: Oxford Academic\n\n\n\n
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\n\n\n@article{osman_diversity_2014,\n\ttitle = {Diversity and abundance of aromatic catabolic genes in lake sediments in response to temperature change},\n\tvolume = {88},\n\tissn = {0168-6496},\n\turl = {http://academic.oup.com/femsec/article/88/3/468/585367},\n\tdoi = {10.1111/1574-6941.12312},\n\tabstract = {Catabolic genes involved in the degradation of aromatic compounds are present in sediments where their abundance and composition differ between lakes and over d},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-08-31},\n\tjournal = {FEMS Microbiology Ecology},\n\tauthor = {Osman, Omneya A. and Gudasz, Cristian and Bertilsson, Stefan},\n\tmonth = jun,\n\tyear = {2014},\n\tnote = {Publisher: Oxford Academic},\n\tkeywords = {\\#nosource},\n\tpages = {468--481},\n}\n\n\n\n\n\n Catabolic genes involved in the degradation of aromatic compounds are present in sediments where their abundance and composition differ between lakes and over d\n
\n\n\n\n \n\n \n \n \n \n \n \n Greenhouse gas production in low-latitude lake sediments responds strongly to warming.\n \n \n \n \n\n\n \n Marotta, H.; Pinho, L.; Gudasz, C.; Bastviken, D.; Tranvik, L. J.; and Enrich-Prast, A.\n\n\n \n\n\n\n Nature Climate Change, 4(6): 467–470. June 2014.\n Number: 6 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{marotta_greenhouse_2014,\n\ttitle = {Greenhouse gas production in low-latitude lake sediments responds strongly to warming},\n\tvolume = {4},\n\tissn = {1758-6798},\n\turl = {http://www.nature.com/articles/nclimate2222},\n\tdoi = {10.1038/nclimate2222},\n\tabstract = {Inland waters collect organic matter from the surrounding land, some of which accumulates to form an important sediment reservoir for organic carbon. Research now shows that rising temperatures in the tropics increase the rate of mineralization and greenhouse gas production from tropical lake sediments by 2.4–4.5 times more than in sub-arctic lakes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-08-31},\n\tjournal = {Nature Climate Change},\n\tauthor = {Marotta, H. and Pinho, L. and Gudasz, C. and Bastviken, D. and Tranvik, L. J. and Enrich-Prast, A.},\n\tmonth = jun,\n\tyear = {2014},\n\tnote = {Number: 6\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {467--470},\n}\n\n\n\n\n\n Inland waters collect organic matter from the surrounding land, some of which accumulates to form an important sediment reservoir for organic carbon. Research now shows that rising temperatures in the tropics increase the rate of mineralization and greenhouse gas production from tropical lake sediments by 2.4–4.5 times more than in sub-arctic lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Regional-scale variation of dissolved organic carbon concentrations in Swedish lakes.\n \n \n \n \n\n\n \n Seekell, D. A.; Lapierre, J.; Pace, M. L.; Gudasz, C.; Sobek, S.; and Tranvik, L. J.\n\n\n \n\n\n\n Limnology and Oceanography, 59(5): 1612–1620. 2014.\n _eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2014.59.5.1612\n\n\n\n
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\n\n\n@article{seekell_regional-scale_2014,\n\ttitle = {Regional-scale variation of dissolved organic carbon concentrations in {Swedish} lakes},\n\tvolume = {59},\n\tcopyright = {© 2014, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tissn = {1939-5590},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2014.59.5.1612},\n\tdoi = {10.4319/lo.2014.59.5.1612},\n\tabstract = {We assessed spatial variability in dissolved organic carbon (DOC) concentrations measured in nearly 2000 Swedish lakes. Inter-lake variance peaked at two different scales, representing within-region and between-region variability. The variation between regions was greater than the variation among lakes within regions. We tested relationships between DOC and runoff, drainage ratio, and altitude for spatial heterogeneity using geographically weighted regression. Relationships varied geographically, but cluster analysis delineated two contiguous regions of similar relationships. Altitude had a significant inverse relationship with DOC in the highlands, and drainage ratio had a significant positive relationship with DOC in the lowlands. These heterogeneous relationships explained regional patterns in DOC concentrations. We conclude that regions, rather than individual lakes, are a key, emergent scale of spatial variability for DOC concentrations. This scale of variability reflects the intersection of environmental gradients (e.g., altitude) with spatially heterogeneous relationships (e.g., DOC—drainage ratio relationship). Regional-scale structure in limnological patterns indicates that individual lakes are not independent from one another, but are emergent groups where DOC concentrations are a function of similar environmental patterns and processes.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2020-08-31},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Seekell, David A. and Lapierre, Jean-François and Pace, Michael L. and Gudasz, Cristian and Sobek, Sebastian and Tranvik, Lars J.},\n\tyear = {2014},\n\tnote = {\\_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2014.59.5.1612},\n\tkeywords = {\\#nosource},\n\tpages = {1612--1620},\n}\n\n\n\n\n\n We assessed spatial variability in dissolved organic carbon (DOC) concentrations measured in nearly 2000 Swedish lakes. Inter-lake variance peaked at two different scales, representing within-region and between-region variability. The variation between regions was greater than the variation among lakes within regions. We tested relationships between DOC and runoff, drainage ratio, and altitude for spatial heterogeneity using geographically weighted regression. Relationships varied geographically, but cluster analysis delineated two contiguous regions of similar relationships. Altitude had a significant inverse relationship with DOC in the highlands, and drainage ratio had a significant positive relationship with DOC in the lowlands. These heterogeneous relationships explained regional patterns in DOC concentrations. We conclude that regions, rather than individual lakes, are a key, emergent scale of spatial variability for DOC concentrations. This scale of variability reflects the intersection of environmental gradients (e.g., altitude) with spatially heterogeneous relationships (e.g., DOC—drainage ratio relationship). Regional-scale structure in limnological patterns indicates that individual lakes are not independent from one another, but are emergent groups where DOC concentrations are a function of similar environmental patterns and processes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Methane fluxes show consistent temperature dependence across microbial to ecosystem scales.\n \n \n \n \n\n\n \n Yvon-Durocher, G.; Allen, A. P.; Bastviken, D.; Conrad, R.; Gudasz, C.; St-Pierre, A.; Thanh-Duc, N.; and del Giorgio, P. A.\n\n\n \n\n\n\n Nature, 507(7493): 488–491. March 2014.\n Number: 7493 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{yvon-durocher_methane_2014,\n\ttitle = {Methane fluxes show consistent temperature dependence across microbial to ecosystem scales},\n\tvolume = {507},\n\tissn = {1476-4687},\n\turl = {http://www.nature.com/articles/nature13164},\n\tdoi = {10.1038/nature13164},\n\tabstract = {Meta-analyses show that the temperature dependence of methane fluxes scales consistently across populations of methanogens, microbial communities and whole ecosystems, and that this temperature dependence is higher than for respiration and photosynthesis; this indicates that global warming may impact the relative contributions of CO2 and CH4 to total greenhouse gas emissions.},\n\tlanguage = {en},\n\tnumber = {7493},\n\turldate = {2020-08-31},\n\tjournal = {Nature},\n\tauthor = {Yvon-Durocher, Gabriel and Allen, Andrew P. and Bastviken, David and Conrad, Ralf and Gudasz, Cristian and St-Pierre, Annick and Thanh-Duc, Nguyen and del Giorgio, Paul A.},\n\tmonth = mar,\n\tyear = {2014},\n\tnote = {Number: 7493\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {488--491},\n}\n\n\n\n\n\n Meta-analyses show that the temperature dependence of methane fluxes scales consistently across populations of methanogens, microbial communities and whole ecosystems, and that this temperature dependence is higher than for respiration and photosynthesis; this indicates that global warming may impact the relative contributions of CO2 and CH4 to total greenhouse gas emissions.\n
\n\n\n\n \n\n \n \n \n \n \n \n The role of herbivores in mediating responses of tundra ecosystems to climate change.\n \n \n \n \n\n\n \n Kaarlejärvi, E.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2014.\n \n\n\n\n
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\n\n\n@phdthesis{kaarlejarvi_role_2014,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {The role of herbivores in mediating responses of tundra ecosystems to climate change},\n\turl = {http://umu.diva-portal.org/smash/record.jsf?pid=diva2:692137},\n\tabstract = {The Arctic areas are warming more rapidly than other parts of the world. Increasing temperatures are predicted to result in shrubification, higher productivity, declining species diversity and new ...},\n\tlanguage = {eng},\n\turldate = {2017-02-13},\n\tschool = {Umeå University},\n\tauthor = {Kaarlejärvi, Elina},\n\tcollaborator = {Olofsson, Johan and Moen, Jon and Eskelinen, Anu},\n\tyear = {2014},\n\tkeywords = {\\#nosource, Climate change, Lemmus lemmus, Rangifer, Species distribution, altitude, biotic interaction, grazer, warming},\n}\n\n\n\n\n\n The Arctic areas are warming more rapidly than other parts of the world. Increasing temperatures are predicted to result in shrubification, higher productivity, declining species diversity and new ...\n
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\n \n \n\n \n \n \n \n \n \n What's up down there?: Climate change effects on subarctic springtail communities and their role in carbon turnover.\n \n \n \n \n\n\n \n Krab, E. J.\n\n\n \n\n\n\n Ph.D. Thesis, June 2013.\n 00001\n\n\n\n
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\n\n\n@phdthesis{krab_whats_2013,\n\ttitle = {What's up down there?: {Climate} change effects on subarctic springtail communities and their role in carbon turnover},\n\tshorttitle = {What's up down there?},\n\turl = {http://dare.ubvu.vu.nl/handle/1871/41481},\n\tabstract = {Cornelissen, J.H.C. [Promotor]},\n\tlanguage = {en},\n\turldate = {2017-02-08},\n\tauthor = {Krab, E. J.},\n\tmonth = jun,\n\tyear = {2013},\n\tnote = {00001},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Cornelissen, J.H.C. [Promotor]\n
\n\n\n\n \n\n \n \n \n \n \n \n Can Humic Water Discharge Counteract Eutrophication in Coastal Waters?.\n \n \n \n \n\n\n \n Andersson, A.; Jurgensone, I.; Rowe, O. F.; Simonelli, P.; Bignert, A.; Lundberg, E.; and Karlsson, J.\n\n\n \n\n\n\n PLOS ONE, 8(4): e61293. 2013.\n \n\n\n\n
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\n\n\n@article{andersson_can_2013,\n\ttitle = {Can {Humic} {Water} {Discharge} {Counteract} {Eutrophication} in {Coastal} {Waters}?},\n\tvolume = {8},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-72705},\n\tdoi = {10.1371/journal.pone.0061293},\n\tabstract = {A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show tha ...},\n\tlanguage = {eng},\n\tnumber = {4},\n\turldate = {2023-07-20},\n\tjournal = {PLOS ONE},\n\tauthor = {Andersson, Agneta and Jurgensone, Iveta and Rowe, Owen F. and Simonelli, Paolo and Bignert, Anders and Lundberg, Erik and Karlsson, Jan},\n\tyear = {2013},\n\tkeywords = {\\#nosource},\n\tpages = {e61293},\n}\n\n\n\n\n\n A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show tha ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Does warming affect growth rate and biomass production of shrubs in the High Arctic?.\n \n \n \n \n\n\n \n Campioli, M.; Schmidt, N. M.; Albert, K. R.; Leblans, N.; Ro-Poulsen, H.; and Michelsen, A.\n\n\n \n\n\n\n Plant Ecology, 214(8): 1049–1058. August 2013.\n \n\n\n\n
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\n\n\n@article{campioli_does_2013,\n\ttitle = {Does warming affect growth rate and biomass production of shrubs in the {High} {Arctic}?},\n\tvolume = {214},\n\tissn = {1573-5052},\n\turl = {https://doi.org/10.1007/s11258-013-0230-x},\n\tdoi = {10.1007/s11258-013-0230-x},\n\tabstract = {Few studies have assessed directly the impact of warming on plant growth and biomass production in the High Arctic. Here, we aimed to investigate the impact of 7 years of warming (open greenhouses) on the aboveground relative growth rate (RGR) of Cassiope tetragona and Salix arctica in North-Eastern Greenland. RGR was assessed for apical (leaves, stem, reproductive organs) and lateral meristems (secondary growth of stem and branches) and accompanied by measures of gross ecosystem production (GEP), branching and tissue carbon (C) concentration. Measurements were based on harvest and biometric methods (for RGR and branching) and gas exchange and chemical analysis (for GEP and C concentration). Warming nearly doubled the apical RGR of Cassiope, whereas it did not affect the apical RGR of Salix. Similarly, secondary growth increased for Cassiope but not for Salix. In particular, warming enhanced the secondary growth of old stem segments of Cassiope formed before the treatment began. The increase in Cassiope RGR was associated with an increase in gross photosynthetic uptake, branching and C concentration in old green tissues. Overall, the different growth measures consistently indicated that temperature limits the growth of Cassiope but not that of Salix in North-Eastern Greenland. Summer warming thus has the potential to stimulate biomass production in the High Arctic but major species-specific differences are expected.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2019-05-20},\n\tjournal = {Plant Ecology},\n\tauthor = {Campioli, Matteo and Schmidt, Niels M. and Albert, Kristian R. and Leblans, Niki and Ro-Poulsen, Helge and Michelsen, Anders},\n\tmonth = aug,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Arctic dwarf-shrubs, Climate change, Experimental warming, Heath tundra, Photosynthesis, Primary and secondary growth rate},\n\tpages = {1049--1058},\n}\n\n\n\n\n\n Few studies have assessed directly the impact of warming on plant growth and biomass production in the High Arctic. Here, we aimed to investigate the impact of 7 years of warming (open greenhouses) on the aboveground relative growth rate (RGR) of Cassiope tetragona and Salix arctica in North-Eastern Greenland. RGR was assessed for apical (leaves, stem, reproductive organs) and lateral meristems (secondary growth of stem and branches) and accompanied by measures of gross ecosystem production (GEP), branching and tissue carbon (C) concentration. Measurements were based on harvest and biometric methods (for RGR and branching) and gas exchange and chemical analysis (for GEP and C concentration). Warming nearly doubled the apical RGR of Cassiope, whereas it did not affect the apical RGR of Salix. Similarly, secondary growth increased for Cassiope but not for Salix. In particular, warming enhanced the secondary growth of old stem segments of Cassiope formed before the treatment began. The increase in Cassiope RGR was associated with an increase in gross photosynthetic uptake, branching and C concentration in old green tissues. Overall, the different growth measures consistently indicated that temperature limits the growth of Cassiope but not that of Salix in North-Eastern Greenland. Summer warming thus has the potential to stimulate biomass production in the High Arctic but major species-specific differences are expected.\n
\n\n\n\n \n\n \n \n \n \n \n \n Cryogenic Soil Activity along Bioclimatic Gradients in Northern Sweden: Insights from Eight Different Proxies.\n \n \n \n \n\n\n \n Klaus, M.; Becher, M.; and Klaminder, J.\n\n\n \n\n\n\n Permafrost and Periglacial Processes, 24(3): 210–223. July 2013.\n 00013\n\n\n\n
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\n\n\n@article{klaus_cryogenic_2013,\n\ttitle = {Cryogenic {Soil} {Activity} along {Bioclimatic} {Gradients} in {Northern} {Sweden}: {Insights} from {Eight} {Different} {Proxies}},\n\tvolume = {24},\n\tissn = {1099-1530},\n\tshorttitle = {Cryogenic {Soil} {Activity} along {Bioclimatic} {Gradients} in {Northern} {Sweden}},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/ppp.1778/abstract},\n\tdoi = {10.1002/ppp.1778},\n\tabstract = {Cryogenic soil activity caused by differential soil movements during freeze-thaw cycles is of fundamental importance for Arctic ecosystem functioning, but its response to climate warming is uncertain. Eight proxies of cryogenic soil activity (including measurements of soil surface motion, vegetation and grey values of aerial photographs) were examined at eight study sites where non-sorted patterned ground spans an elevation gradient (400–1150 m asl) and a precipitation gradient (300–1000 mm yr-1) near Abisko, northern Sweden. Six proxies were significantly correlated with each other (mean {\\textbar}r{\\textbar} = 0.5). Soil surface motion increased by three to five times along the precipitation gradient and was two to four times greater at intermediate elevations than at low and high elevations, a pattern reflected by vegetation assemblages. The results suggest that inferences about how cryogenic soil activity changes with climate are independent of the choice of the proxy, although some proxies should be applied carefully. Four preferred proxies indicate that cryogenic soil activity may respond differently to climate warming along the elevation gradient and could be greatly modified by precipitation. This underlines the strong but spatially complex response of cryogenic processes to climate change in the Arctic. Copyright © 2013 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {Permafrost and Periglacial Processes},\n\tauthor = {Klaus, Marcus and Becher, Marina and Klaminder, Jonatan},\n\tmonth = jul,\n\tyear = {2013},\n\tnote = {00013},\n\tkeywords = {\\#nosource, Cryoturbation, climosequence, cryoturbation, differential frost heave, non-sorted circle, periglacial geomorphology, soil disturbance},\n\tpages = {210--223},\n}\n\n\n\n\n\n Cryogenic soil activity caused by differential soil movements during freeze-thaw cycles is of fundamental importance for Arctic ecosystem functioning, but its response to climate warming is uncertain. Eight proxies of cryogenic soil activity (including measurements of soil surface motion, vegetation and grey values of aerial photographs) were examined at eight study sites where non-sorted patterned ground spans an elevation gradient (400–1150 m asl) and a precipitation gradient (300–1000 mm yr-1) near Abisko, northern Sweden. Six proxies were significantly correlated with each other (mean \\textbarr\\textbar = 0.5). Soil surface motion increased by three to five times along the precipitation gradient and was two to four times greater at intermediate elevations than at low and high elevations, a pattern reflected by vegetation assemblages. The results suggest that inferences about how cryogenic soil activity changes with climate are independent of the choice of the proxy, although some proxies should be applied carefully. Four preferred proxies indicate that cryogenic soil activity may respond differently to climate warming along the elevation gradient and could be greatly modified by precipitation. This underlines the strong but spatially complex response of cryogenic processes to climate change in the Arctic. Copyright © 2013 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stable carbon isotopes from Torneträsk, northern Sweden provide a millennial length reconstruction of summer sunshine and its relationship to Arctic circulation.\n \n \n \n \n\n\n \n Loader, N. J.; Young, G. H. F.; Grudd, H.; and McCarroll, D.\n\n\n \n\n\n\n Quaternary Science Reviews, 62: 97–113. February 2013.\n \n\n\n\n
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\n\n\n@article{loader_stable_2013,\n\ttitle = {Stable carbon isotopes from {Torneträsk}, northern {Sweden} provide a millennial length reconstruction of summer sunshine and its relationship to {Arctic} circulation},\n\tvolume = {62},\n\tissn = {0277-3791},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0277379112004854},\n\tdoi = {10.1016/j.quascirev.2012.11.014},\n\tabstract = {This paper presents results from the first 1100 years of a long stable carbon isotope chronology currently in development from Scots Pine (Pinus sylvestris L.) trees growing in the Torneträsk region of northern Sweden. The isotope record currently comprises a total of 74 trees with a mean annual replication of {\\textgreater}12, thereby enabling it to be compared directly with other tree-ring based palæoclimate reconstructions from this region. In developing the reconstruction, several key topics in isotope dendroclimatology (chronology construction, replication, CO2 adjustment and age trends) were addressed. The resulting carbon isotope series is calibrated against instrumental data from the closest meteorological station at Abisko (AD1913–2008) to provide a record of June–August sunshine for northern Fennoscandia. This parameter is closely linked to the direct control of assimilation rate; Photosynthetically Active Radiation (PAR) and the indirect measures; mean July–August temperature and percent cloud cover. The coupled response of summer sunshine and temperature in this region permits a multi-parameter comparison with a local reconstruction of past temperature variability based upon tree growth proxies to explore the stability of this coupling through time. Several periods are identified where the temperature (X-ray density) and sunshine (stable carbon isotope ratio) records diverge. The most significant and sustained of these occur between c AD1200–1380 and c AD1550–1780, providing evidence for a cool, sunny, two-phase “Little Ice Age”. Whilst summer sunshine reconstructed for the 20th century is significantly different from the mean of the last 1100 years (P {\\textless} 0.01), conditions during the early mediæval period are similar to those experienced in northern Fennoscandia during the 20th century (P {\\textgreater} 0.01), so it is the 17th–18th, and to a lesser extent, the 13th centuries rather than the early mediæval period that appear anomalous when viewed within the context of the last 1100 years. The observed departures between temperature and sunshine are interpreted as indicating a change in large-scale circulation associated with a southward migration of the Polar Front. Such a change, affecting the Northern Annular Mode (Arctic Oscillation) would result in more stable anticyclonic conditions (cool, bright, summers) over northern Fennoscandia, thus providing a testable mechanism for the development of a multi-phase, time-transgressive “Little Ice Age” across Europe.},\n\turldate = {2019-09-19},\n\tjournal = {Quaternary Science Reviews},\n\tauthor = {Loader, N. J. and Young, G. H. F. and Grudd, H. and McCarroll, D.},\n\tmonth = feb,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Arctic oscillation, Climate change, Fennoscandia, Northern annular mode, Photosynthetically active radiation (PAR), Torneträsk, Tree-ring, “Little Ice Age”},\n\tpages = {97--113},\n}\n\n\n\n\n\n This paper presents results from the first 1100 years of a long stable carbon isotope chronology currently in development from Scots Pine (Pinus sylvestris L.) trees growing in the Torneträsk region of northern Sweden. The isotope record currently comprises a total of 74 trees with a mean annual replication of \\textgreater12, thereby enabling it to be compared directly with other tree-ring based palæoclimate reconstructions from this region. In developing the reconstruction, several key topics in isotope dendroclimatology (chronology construction, replication, CO2 adjustment and age trends) were addressed. The resulting carbon isotope series is calibrated against instrumental data from the closest meteorological station at Abisko (AD1913–2008) to provide a record of June–August sunshine for northern Fennoscandia. This parameter is closely linked to the direct control of assimilation rate; Photosynthetically Active Radiation (PAR) and the indirect measures; mean July–August temperature and percent cloud cover. The coupled response of summer sunshine and temperature in this region permits a multi-parameter comparison with a local reconstruction of past temperature variability based upon tree growth proxies to explore the stability of this coupling through time. Several periods are identified where the temperature (X-ray density) and sunshine (stable carbon isotope ratio) records diverge. The most significant and sustained of these occur between c AD1200–1380 and c AD1550–1780, providing evidence for a cool, sunny, two-phase “Little Ice Age”. Whilst summer sunshine reconstructed for the 20th century is significantly different from the mean of the last 1100 years (P \\textless 0.01), conditions during the early mediæval period are similar to those experienced in northern Fennoscandia during the 20th century (P \\textgreater 0.01), so it is the 17th–18th, and to a lesser extent, the 13th centuries rather than the early mediæval period that appear anomalous when viewed within the context of the last 1100 years. The observed departures between temperature and sunshine are interpreted as indicating a change in large-scale circulation associated with a southward migration of the Polar Front. Such a change, affecting the Northern Annular Mode (Arctic Oscillation) would result in more stable anticyclonic conditions (cool, bright, summers) over northern Fennoscandia, thus providing a testable mechanism for the development of a multi-phase, time-transgressive “Little Ice Age” across Europe.\n
\n\n\n\n \n\n \n \n \n \n \n \n An Appraisal of the Use of Hydrogen-Isotope Methods to Delineate Origins of Migratory Saw-whet Owls in North America.\n \n \n \n \n\n\n \n De Ruyck, C.; Hobson, K. A.; Koper, N.; Larson, K. W.; and Wassenaar, L. I.\n\n\n \n\n\n\n The Condor, 115(2): 366–374. May 2013.\n 00003\n\n\n\n
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\n\n\n\n@article{de_ruyck_appraisal_2013,\n\ttitle = {An {Appraisal} of the {Use} of {Hydrogen}-{Isotope} {Methods} to {Delineate} {Origins} of {Migratory} {Saw}-whet {Owls} in {North} {America}},\n\tvolume = {115},\n\tissn = {00105422, 1938-5129},\n\turl = {http://www.jstor.org/discover/10.1525/cond.2013.120019?uid=28646&uid=3738984&uid=2134&uid=2&uid=70&uid=28645&uid=3&uid=67&uid=62&sid=21102288698161},\n\tdoi = {10.1525/cond.2013.120019},\n\tnumber = {2},\n\turldate = {2013-06-06},\n\tjournal = {The Condor},\n\tauthor = {De Ruyck, Chris and Hobson, Keith A. and Koper, Nicola and Larson, Keith W. and Wassenaar, Leonard I.},\n\tmonth = may,\n\tyear = {2013},\n\tnote = {00003},\n\tkeywords = {\\#nosource},\n\tpages = {366--374},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Characterisation of a transcriptome to find sequence differences between two differentially migrating subspecies of the willow warbler Phylloscopus trochilus.\n \n \n \n \n\n\n \n Lundberg, M.; Boss, J.; Canbäck, B.; Liedvogel, M.; Larson, K. W.; Grahn, M.; Åkesson, S.; Bensch, S.; and Wright, A.\n\n\n \n\n\n\n BMC Genomics, 14(1): 330. May 2013.\n 00017 Animal migration requires adaptations in morphological, physiological and behavioural traits. Several of these traits have been shown to possess a strong heritable component in birds, but little is known about their genetic architecture. Here we used 454 sequencing of brain-derived transcriptomes from two differentially migrating subspecies of the willow warbler Phylloscopus trochilus to detect genes potentially underlying traits associated with migration.\n\n\n\n
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\n\n\n@article{lundberg_characterisation_2013,\n\ttitle = {Characterisation of a transcriptome to find sequence differences between two differentially migrating subspecies of the willow warbler {Phylloscopus} trochilus},\n\tvolume = {14},\n\tcopyright = {http://creativecommons.org/licenses/by/2.0/},\n\tissn = {1471-2164},\n\turl = {http://www.biomedcentral.com.ludwig.lub.lu.se/1471-2164/14/330/abstract},\n\tdoi = {10.1186/1471-2164-14-330},\n\tabstract = {Animal migration requires adaptations in morphological, physiological and behavioural traits. Several of these traits have been shown to possess a strong heritable component in birds, but little is known about their genetic architecture. Here we used 454 sequencing of brain-derived transcriptomes from two differentially migrating subspecies of the willow warbler Phylloscopus trochilus to detect genes potentially underlying traits associated with migration.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2013-05-18},\n\tjournal = {BMC Genomics},\n\tauthor = {Lundberg, Max and Boss, John and Canbäck, Björn and Liedvogel, Miriam and Larson, Keith W. and Grahn, Mats and Åkesson, Susanne and Bensch, Staffan and Wright, Anthony},\n\tmonth = may,\n\tyear = {2013},\n\tnote = {00017 \nAnimal migration requires adaptations in morphological, physiological and behavioural traits. Several of these traits have been shown to possess a strong heritable component in birds, but little is known about their genetic architecture. Here we used 454 sequencing of brain-derived transcriptomes from two differentially migrating subspecies of the willow warbler Phylloscopus trochilus to detect genes potentially underlying traits associated with migration.},\n\tkeywords = {\\#nosource, 454 Transcriptome sequencing, Genetics of migration, Phylloscopus},\n\tpages = {330},\n}\n\n\n\n\n\n Animal migration requires adaptations in morphological, physiological and behavioural traits. Several of these traits have been shown to possess a strong heritable component in birds, but little is known about their genetic architecture. Here we used 454 sequencing of brain-derived transcriptomes from two differentially migrating subspecies of the willow warbler Phylloscopus trochilus to detect genes potentially underlying traits associated with migration.\n
\n\n\n\n \n\n \n \n \n \n \n Soil organic phosphorus transformations in a boreal forest chronosequence.\n \n \n \n\n\n \n Vincent, A. G.; Vestergren, J.; Grobner, G.; Persson, P.; Schleucher, J.; and Giesler, R.\n\n\n \n\n\n\n Plant and Soil, 367(1-2): 149–162. June 2013.\n 00020\n\n\n\n
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\n\n\n@article{vincent_soil_2013,\n\ttitle = {Soil organic phosphorus transformations in a boreal forest chronosequence},\n\tvolume = {367},\n\tissn = {0032-079X},\n\tdoi = {10.1007/s11104-013-1731-z},\n\tabstract = {Soil phosphorus (P) composition changes with ecosystem development, leading to changes in P bioavailability and ecosystem properties. Little is known, however, about how soil P transformations proceed with ecosystem development in boreal regions. We used 1-dimensional P-31 and 2-dimensional H-1, P-31 correlation nuclear magnetic resonance (NMR) spectroscopy to characterise soil organic P transformations in humus horizons across a 7,800 year-old chronosequence in Vasterbotten, northern Sweden. Total soil P concentration varied little along the chronosequence, but P compounds followed three trends. Firstly, the concentrations of DNA, 2-aminoethyl phosphonic acid, and polyphosphate, increased up to 1,200-2,700 years and then declined. Secondly, the abundances of alpha- and beta-glycerophosphate, nucleotides, and pyrophosphate, were higher at the youngest site compared with all other sites. Lastly, concentrations of inositol hexakisphosphate fluctuated with site age. The largest changes in soil P composition tended to occur in young sites which also experience the largest shifts in plant community composition. The apparent lack of change in total soil P is consistent with the youth and nitrogen limited nature of the Vasterbotten chronosequence. Based on 2D NMR spectra, around 40 \\% of extractable soil organic P appeared to occur in live microbial cells. The observed trends in soil organic P may be related to shifts in plant community composition (and associated changes in soil microorganisms) along the studied chronosequence, but further studies are needed to confirm this.},\n\tlanguage = {English},\n\tnumber = {1-2},\n\tjournal = {Plant and Soil},\n\tauthor = {Vincent, Andrea G. and Vestergren, Johan and Grobner, Gerhard and Persson, Per and Schleucher, Jurgen and Giesler, Reiner},\n\tmonth = jun,\n\tyear = {2013},\n\tnote = {00020},\n\tkeywords = {\\#nosource, 1d (pnmr)-p-31, 2D H-1, P-31 correlation NMR, Inositol hexakisphosphate, Podzolization, Ribonucleic acid (RNA), Vasterbotten chronosequence, community structure, humus layer, iron accumulation, land-uplift coast, northern sweden, nuclear-magnetic-resonance, p-31 nmr-spectroscopy, primary succession transect, ribosomal-rna, western finland},\n\tpages = {149--162},\n}\n\n\n\n\n\n Soil phosphorus (P) composition changes with ecosystem development, leading to changes in P bioavailability and ecosystem properties. Little is known, however, about how soil P transformations proceed with ecosystem development in boreal regions. We used 1-dimensional P-31 and 2-dimensional H-1, P-31 correlation nuclear magnetic resonance (NMR) spectroscopy to characterise soil organic P transformations in humus horizons across a 7,800 year-old chronosequence in Vasterbotten, northern Sweden. Total soil P concentration varied little along the chronosequence, but P compounds followed three trends. Firstly, the concentrations of DNA, 2-aminoethyl phosphonic acid, and polyphosphate, increased up to 1,200-2,700 years and then declined. Secondly, the abundances of alpha- and beta-glycerophosphate, nucleotides, and pyrophosphate, were higher at the youngest site compared with all other sites. Lastly, concentrations of inositol hexakisphosphate fluctuated with site age. The largest changes in soil P composition tended to occur in young sites which also experience the largest shifts in plant community composition. The apparent lack of change in total soil P is consistent with the youth and nitrogen limited nature of the Vasterbotten chronosequence. Based on 2D NMR spectra, around 40 % of extractable soil organic P appeared to occur in live microbial cells. The observed trends in soil organic P may be related to shifts in plant community composition (and associated changes in soil microorganisms) along the studied chronosequence, but further studies are needed to confirm this.\n
\n\n\n\n \n\n \n \n \n \n \n \n Community and Ecosystem Responses to Elevational Gradients: Processes, Mechanisms, and Insights for Global Change.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Sanders, N. J.; and Wardle, D. A.\n\n\n \n\n\n\n Annual Review of Ecology, Evolution, and Systematics, 44(1): 261–280. 2013.\n 00090\n\n\n\n
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\n\n\n@article{sundqvist_community_2013,\n\ttitle = {Community and {Ecosystem} {Responses} to {Elevational} {Gradients}: {Processes}, {Mechanisms}, and {Insights} for {Global} {Change}},\n\tvolume = {44},\n\tshorttitle = {Community and {Ecosystem} {Responses} to {Elevational} {Gradients}},\n\turl = {http://dx.doi.org/10.1146/annurev-ecolsys-110512-135750},\n\tdoi = {10.1146/annurev-ecolsys-110512-135750},\n\tabstract = {Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients. There are also many exceptions, sometimes because other factors such as precipitation can also vary with elevation. Given this complexity, our capacity to predict when and why the same variable responds differently among disparate elevational gradients is often limited. Furthermore, there is utility in using elevational gradients for understanding community and ecosystem responses to global climate change at much larger spatial and temporal scales than is possible through conventional ecological experiments. However, future studies that integrate elevational gradient approaches with experimental manipulations will provide powerful information that can improve predictions of climate change impacts within and across ecosystems.},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Annual Review of Ecology, Evolution, and Systematics},\n\tauthor = {Sundqvist, Maja K. and Sanders, Nathan J. and Wardle, David A.},\n\tyear = {2013},\n\tnote = {00090},\n\tkeywords = {\\#nosource},\n\tpages = {261--280},\n}\n\n\n\n\n\n Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients. There are also many exceptions, sometimes because other factors such as precipitation can also vary with elevation. Given this complexity, our capacity to predict when and why the same variable responds differently among disparate elevational gradients is often limited. Furthermore, there is utility in using elevational gradients for understanding community and ecosystem responses to global climate change at much larger spatial and temporal scales than is possible through conventional ecological experiments. However, future studies that integrate elevational gradient approaches with experimental manipulations will provide powerful information that can improve predictions of climate change impacts within and across ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Buried soil organic inclusions in non-sorted circles fields in northern Sweden: Age and Paleoclimatic context.\n \n \n \n \n\n\n \n Becher, M.; Olid, C.; and Klaminder, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 118(1): 104–111. March 2013.\n 00012\n\n\n\n
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\n\n\n@article{becher_buried_2013,\n\ttitle = {Buried soil organic inclusions in non-sorted circles fields in northern {Sweden}: {Age} and {Paleoclimatic} context},\n\tvolume = {118},\n\tissn = {2169-8961},\n\tshorttitle = {Buried soil organic inclusions in non-sorted circles fields in northern {Sweden}},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20016/abstract},\n\tdoi = {10.1002/jgrg.20016},\n\tabstract = {Although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long-term buildup of carbon in arctic soils, when and why buried horizons formed as result of cryoturbation in northern Sweden remain unclear. In this study, we used 14C and 210Pb dating to assess when organic matter was buried within non-sorted circles fields near Abisko in northern Sweden. In addition, we used aerial photos from 1959 and 2008 to detect eventual trends in cryogenic activities during this period. We found that organic matter from former organic horizons (stratigraphically intact or partly fragmented) corresponds to three major periods: 0–100 A.D., 900–1250 A.D., and 1650–1950 A.D. The latter two periods were indicated by several dated samples, while the extent of the oldest period is more uncertainty (indicated by only one sample). The aerial photos suggest a net overgrowth by shrub vegetation of previously exposed mineral soil surfaces since 1959. This overgrowth trend was seen in most of the studied fields (92 out of 137 analyzed fields), indicating that the cryogenic activity has mainly decreased in studied non-sorted circles fields since the 1950s. This latter interpretation is also supported by the absence of buried organic layers formed during the last decades. We suggest that the organic matter was buried during the transition from longer cold periods to warmer conditions. We believe these climatic shifts could have triggered regional scale burial of soil organic matter and thus affected how these soils sequestered carbon.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Becher, Marina and Olid, Carolina and Klaminder, Jonatan},\n\tmonth = mar,\n\tyear = {2013},\n\tnote = {00012},\n\tkeywords = {\\#nosource, Arctic, Image processing, Pb-210, Permafrost, cryosphere, and high-latitude processes, Soil, carbon cycling, frost creep, non-sorted circles, radiocarbon},\n\tpages = {104--111},\n}\n\n\n\n\n\n Although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long-term buildup of carbon in arctic soils, when and why buried horizons formed as result of cryoturbation in northern Sweden remain unclear. In this study, we used 14C and 210Pb dating to assess when organic matter was buried within non-sorted circles fields near Abisko in northern Sweden. In addition, we used aerial photos from 1959 and 2008 to detect eventual trends in cryogenic activities during this period. We found that organic matter from former organic horizons (stratigraphically intact or partly fragmented) corresponds to three major periods: 0–100 A.D., 900–1250 A.D., and 1650–1950 A.D. The latter two periods were indicated by several dated samples, while the extent of the oldest period is more uncertainty (indicated by only one sample). The aerial photos suggest a net overgrowth by shrub vegetation of previously exposed mineral soil surfaces since 1959. This overgrowth trend was seen in most of the studied fields (92 out of 137 analyzed fields), indicating that the cryogenic activity has mainly decreased in studied non-sorted circles fields since the 1950s. This latter interpretation is also supported by the absence of buried organic layers formed during the last decades. We suggest that the organic matter was buried during the transition from longer cold periods to warmer conditions. We believe these climatic shifts could have triggered regional scale burial of soil organic matter and thus affected how these soils sequestered carbon.\n
\n\n\n\n \n\n \n \n \n \n \n Livestock grazing in intermountain depressional wetlands-Effects on plant strategies, soil characteristics and biomass.\n \n \n \n\n\n \n Teuber, L. M.; Hoelzel, N.; and Fraser, L. H.\n\n\n \n\n\n\n Agriculture Ecosystems & Environment, 175: 21–28. August 2013.\n 00011\n\n\n\n
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\n\n\n@article{teuber_livestock_2013,\n\ttitle = {Livestock grazing in intermountain depressional wetlands-{Effects} on plant strategies, soil characteristics and biomass},\n\tvolume = {175},\n\tissn = {0167-8809},\n\tdoi = {10.1016/j.agee.2013.04.017},\n\tabstract = {Prairie wetlands are considered valuable habitat for plants, birds, and wildlife. Livestock use of these wetlands can create conflicts with conservation issues. To achieve proper management, patterns and processes induced by grazing livestock need to be understood. In this study, we examined interactions of livestock use, soil and vegetation of depressional prairie wetlands in British Columbia, Canada. Plant community composition; biomass, and soil properties (bulk density, salinity, nitrogen and carbon content) were sampled on transects in marsh and wet meadow vegetation zones of wetlands along a grazing intensity gradient. Grime's CSR-strategies were used to calibrate strategy signatures, which indicate the importance of competition, stress and disturbance. Heavily grazed sites had higher salinity, less biomass, and proportionally less belowground biomass. Differences concerning strategies between vegetation zones were only apparent in un/lightly grazed sites, where stress was higher in marsh and competition higher in wet meadow zones. Livestock use and nitrogen were positively correlated with ruderal abundance and negatively correlated with competitors and stress-tolerators. Livestock use was identified to be most influential on plant strategies. Our results indicate that heavy livestock use significantly alters vegetation patterns and processes in prairie wetlands and may have negative impact on valuable habitat. Management decisions should consider reduced livestock access and incorporate conservation issues in grazing schemes. (C) 2013 Elsevier B.V. All rights reserved.},\n\tlanguage = {English},\n\tjournal = {Agriculture Ecosystems \\& Environment},\n\tauthor = {Teuber, Laurenz M. and Hoelzel, Norbert and Fraser, Lauchlan H.},\n\tmonth = aug,\n\tyear = {2013},\n\tnote = {00011},\n\tkeywords = {\\#nosource, CSR-model, Depressional wetlands, Ecosystems, Ruderals, Salinification, Soil salinity, community, competition, diversity, impact, large herbivores, mixed-grass, physical-properties, prairie wetlands, species density, stress, vegetation structure},\n\tpages = {21--28},\n}\n\n\n\n\n\n Prairie wetlands are considered valuable habitat for plants, birds, and wildlife. Livestock use of these wetlands can create conflicts with conservation issues. To achieve proper management, patterns and processes induced by grazing livestock need to be understood. In this study, we examined interactions of livestock use, soil and vegetation of depressional prairie wetlands in British Columbia, Canada. Plant community composition; biomass, and soil properties (bulk density, salinity, nitrogen and carbon content) were sampled on transects in marsh and wet meadow vegetation zones of wetlands along a grazing intensity gradient. Grime's CSR-strategies were used to calibrate strategy signatures, which indicate the importance of competition, stress and disturbance. Heavily grazed sites had higher salinity, less biomass, and proportionally less belowground biomass. Differences concerning strategies between vegetation zones were only apparent in un/lightly grazed sites, where stress was higher in marsh and competition higher in wet meadow zones. Livestock use and nitrogen were positively correlated with ruderal abundance and negatively correlated with competitors and stress-tolerators. Livestock use was identified to be most influential on plant strategies. Our results indicate that heavy livestock use significantly alters vegetation patterns and processes in prairie wetlands and may have negative impact on valuable habitat. Management decisions should consider reduced livestock access and incorporate conservation issues in grazing schemes. (C) 2013 Elsevier B.V. All rights reserved.\n
\n\n\n\n \n\n \n \n \n \n \n \n Total waterborne carbon export and DOC composition from ten nested subarctic peatland catchments—importance of peatland cover, groundwater influence, and inter-annual variability of precipitation patterns.\n \n \n \n \n\n\n \n Olefeldt, D.; Roulet, N.; Giesler, R.; and Persson, A.\n\n\n \n\n\n\n Hydrological Processes, 27(16): 2280–2294. July 2013.\n 00036\n\n\n\n
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\n\n\n@article{olefeldt_total_2013,\n\ttitle = {Total waterborne carbon export and {DOC} composition from ten nested subarctic peatland catchments—importance of peatland cover, groundwater influence, and inter-annual variability of precipitation patterns},\n\tvolume = {27},\n\tissn = {1099-1085},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.9358/abstract},\n\tdoi = {10.1002/hyp.9358},\n\tabstract = {Waterborne carbon (C) export from terrestrial ecosystems is a potentially important flux for the net catchment C balance and links the biogeochemical C cycling of terrestrial ecosystems to their downstream aquatic ecosystems. We have monitored hydrology and stream chemistry over 3 years in ten nested catchments (0.6–15.1 km2) with variable peatland cover (0\\%–22\\%) and groundwater influence in subarctic Sweden. Total waterborne C export, including dissolved and particulate organic carbon (DOC and POC) and dissolved inorganic carbon (DIC), ranged between 2.8 and 7.3 g m–2 year–1, representing {\\textasciitilde}10\\%–30\\% of catchment net ecosystem exchange of CO2. Several characteristics of catchment waterborne C export were affected by interacting effects of peatland cover and groundwater influence, including magnitude and timing, partitioning into DOC, POC, and DIC and chemical composition of the exported DOC. Waterborne C export was greater during the wetter years, equivalent to an average change in export of {\\textasciitilde}2 g m–2 year–1 per 100 mm of precipitation. Wetter years led to a greater relative increase in DIC export than DOC export due to an inferred relative shift in dominance from shallow organic flow pathways to groundwater sources. Indices of DOC composition (SUVA254 and a250/a365) indicated that DOC aromaticity and average molecular weight increased with catchment peatland cover and decreased with increased groundwater influence. Our results provide examples on how waterborne C export and DOC composition might be affected by climate change. Copyright © 2012 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {16},\n\turldate = {2017-02-07},\n\tjournal = {Hydrological Processes},\n\tauthor = {Olefeldt, David and Roulet, Nigel and Giesler, Reiner and Persson, Andreas},\n\tmonth = jul,\n\tyear = {2013},\n\tnote = {00036},\n\tkeywords = {\\#nosource, discontinuous permafrost, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), groundwater, peatlands, subarctic},\n\tpages = {2280--2294},\n}\n\n\n\n\n\n Waterborne carbon (C) export from terrestrial ecosystems is a potentially important flux for the net catchment C balance and links the biogeochemical C cycling of terrestrial ecosystems to their downstream aquatic ecosystems. We have monitored hydrology and stream chemistry over 3 years in ten nested catchments (0.6–15.1 km2) with variable peatland cover (0%–22%) and groundwater influence in subarctic Sweden. Total waterborne C export, including dissolved and particulate organic carbon (DOC and POC) and dissolved inorganic carbon (DIC), ranged between 2.8 and 7.3 g m–2 year–1, representing ~10%–30% of catchment net ecosystem exchange of CO2. Several characteristics of catchment waterborne C export were affected by interacting effects of peatland cover and groundwater influence, including magnitude and timing, partitioning into DOC, POC, and DIC and chemical composition of the exported DOC. Waterborne C export was greater during the wetter years, equivalent to an average change in export of ~2 g m–2 year–1 per 100 mm of precipitation. Wetter years led to a greater relative increase in DIC export than DOC export due to an inferred relative shift in dominance from shallow organic flow pathways to groundwater sources. Indices of DOC composition (SUVA254 and a250/a365) indicated that DOC aromaticity and average molecular weight increased with catchment peatland cover and decreased with increased groundwater influence. Our results provide examples on how waterborne C export and DOC composition might be affected by climate change. Copyright © 2012 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n Catchment-scale carbon exports across a subarctic landscape gradient.\n \n \n \n \n\n\n \n Giesler, R.; Lyon, S. W.; Mörth, C.; Karlsson, J.; Jantze, E. J.; Destouni, G.; and Humborg, C.\n\n\n \n\n\n\n Biogeosciences Discussions, 10(5): 7953–7988. May 2013.\n 00001\n\n\n\n
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\n\n\n\n@article{giesler_catchment-scale_2013,\n\ttitle = {Catchment-scale carbon exports across a subarctic landscape gradient},\n\tvolume = {10},\n\tissn = {1810-6285},\n\turl = {http://www.biogeosciences-discuss.net/10/7953/2013/},\n\tdoi = {10.5194/bgd-10-7953-2013},\n\tnumber = {5},\n\turldate = {2013-11-15},\n\tjournal = {Biogeosciences Discussions},\n\tauthor = {Giesler, R. and Lyon, S. W. and Mörth, C.-M. and Karlsson, J. and Jantze, E. J. and Destouni, G. and Humborg, C.},\n\tmonth = may,\n\tyear = {2013},\n\tnote = {00001},\n\tkeywords = {\\#nosource},\n\tpages = {7953--7988},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Inferring the ecology of willow warblers during their winter moult by sequential stable isotope analyses of remiges.\n \n \n \n \n\n\n \n Larson, K. W.; Liedvogel, M.; Bensch, S.; Åkesson, S.; Wassenaar, L. I.; and Hobson, K. A.\n\n\n \n\n\n\n Journal of Avian Biology, 44(6): 561–566. November 2013.\n 00002\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{larson_inferring_2013,\n\ttitle = {Inferring the ecology of willow warblers during their winter moult by sequential stable isotope analyses of remiges},\n\tvolume = {44},\n\tcopyright = {© 2013 The Authors},\n\tissn = {1600-048X},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1600-048X.2013.00050.x/abstract},\n\tdoi = {10.1111/j.1600-048X.2013.00050.x},\n\tabstract = {We present a comparison of feather stable isotope (δ13C, δ15N) patterns representing the habitat and diet conditions for two subspecies of willow warblers Phylloscopus trochilus that breed in parapatry, but winter in different regions of sub-Saharan Africa. Previous analyses have shown that on average winter moulted innermost primaries (P1) show subspecific differences in δ15N values, although individuals show substantial variation for both δ13C and δ15N within the subspecies. We examined whether corresponding variation in the timing of the winter moult, as reflected by consistent intra-wing correlations for individual's δ13C and δ15N values, could explain some of the previously observed isotopic variation. Further, differential subspecific adaptations to winter precipitation patterns across Africa might result in a variable degree of site fidelity or itinerancy during moult. We found no consistent trend in isotopic values from innermost to outermost primaries, thus inter-individual variation in the timing of moult does not explain the subspecific isotopic variation for P1. Patterns in wing feather δ13C and δ15N values indicated that 41\\% of the individuals from both subspecies shifted their diet or habitats during winter moult. Importantly, despite well-documented itinerancy in willow warblers during the winter, 59\\% of the individuals had feather isotope values consistent with stable use of habitats or diets during winter moult. Repeatability analyses suggest that individuals of both subspecies initiate moult in similar habitats from year-to-year while feeding on isotopically similar diets.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2014-10-25},\n\tjournal = {Journal of Avian Biology},\n\tauthor = {Larson, Keith W. and Liedvogel, Miriam and Bensch, Staffan and Åkesson, Susanne and Wassenaar, Leonard I. and Hobson, Keith A.},\n\tmonth = nov,\n\tyear = {2013},\n\tnote = {00002},\n\tkeywords = {\\#nosource},\n\tpages = {561--566},\n}\n\n\n\n\n\n We present a comparison of feather stable isotope (δ13C, δ15N) patterns representing the habitat and diet conditions for two subspecies of willow warblers Phylloscopus trochilus that breed in parapatry, but winter in different regions of sub-Saharan Africa. Previous analyses have shown that on average winter moulted innermost primaries (P1) show subspecific differences in δ15N values, although individuals show substantial variation for both δ13C and δ15N within the subspecies. We examined whether corresponding variation in the timing of the winter moult, as reflected by consistent intra-wing correlations for individual's δ13C and δ15N values, could explain some of the previously observed isotopic variation. Further, differential subspecific adaptations to winter precipitation patterns across Africa might result in a variable degree of site fidelity or itinerancy during moult. We found no consistent trend in isotopic values from innermost to outermost primaries, thus inter-individual variation in the timing of moult does not explain the subspecific isotopic variation for P1. Patterns in wing feather δ13C and δ15N values indicated that 41% of the individuals from both subspecies shifted their diet or habitats during winter moult. Importantly, despite well-documented itinerancy in willow warblers during the winter, 59% of the individuals had feather isotope values consistent with stable use of habitats or diets during winter moult. Repeatability analyses suggest that individuals of both subspecies initiate moult in similar habitats from year-to-year while feeding on isotopically similar diets.\n
\n\n\n\n \n\n \n \n \n \n \n Benthic organic carbon release stimulates bacterioplankton production in a clear-water subarctic lake.\n \n \n \n\n\n \n Rodriguez, P.; Ask, J.; Hein, C. L.; Jansson, M.; and Karlsson, J.\n\n\n \n\n\n\n Freshwater Science, 32(1): 176–182. March 2013.\n \n\n\n\n
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\n\n\n@article{rodriguez_benthic_2013,\n\ttitle = {Benthic organic carbon release stimulates bacterioplankton production in a clear-water subarctic lake},\n\tvolume = {32},\n\tissn = {2161-9565},\n\tdoi = {10.1899/12-005.1},\n\tabstract = {We carried out a set of experiments in a small clear-water lake in northern Sweden during summer 2010 to assess the effect of organic C (OC) released from epipelic algae on pelagic bacterial production (BP). The release rate of OC (dissolved and particulate) from epipelic algae was similar to 45.4 ng C m(-2) h(-1) Bacterioplankton uptake of dissolved OC was P-limited, and pelagic primary production (PP) was colimited by N and P. Pelagic BP (3.2 +/- 6 mu g C L-1 h(-1)) exceeded pelagic PP (0.012 +/- 0.008 mu g C L-1 h(-1)). Pelagic BP was higher in lake water in contact with sediments and the epipelic algae growing on their surface than in water separated from the sediments. Epipelic algae release OC to lake water and potentially stimulate pelagic BP. However, exploitation of benthic OC probably is suboptimal because of nutrient limitation (primarily by inorganic P) of BP.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Freshwater Science},\n\tauthor = {Rodriguez, Patricia and Ask, Jenny and Hein, Catherine L. and Jansson, Mats and Karlsson, Jan},\n\tmonth = mar,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Algae, Sediment, allochthonous carbon, bacterial-growth, bacterioplankton production, benthic algae, c-13 addition experiments, clear-water lake, light, microphytobenthos, northern sweden, nutrients, organic carbon, phosphorus, phytoplankton production},\n\tpages = {176--182},\n}\n\n\n\n\n\n We carried out a set of experiments in a small clear-water lake in northern Sweden during summer 2010 to assess the effect of organic C (OC) released from epipelic algae on pelagic bacterial production (BP). The release rate of OC (dissolved and particulate) from epipelic algae was similar to 45.4 ng C m(-2) h(-1) Bacterioplankton uptake of dissolved OC was P-limited, and pelagic primary production (PP) was colimited by N and P. Pelagic BP (3.2 +/- 6 mu g C L-1 h(-1)) exceeded pelagic PP (0.012 +/- 0.008 mu g C L-1 h(-1)). Pelagic BP was higher in lake water in contact with sediments and the epipelic algae growing on their surface than in water separated from the sediments. Epipelic algae release OC to lake water and potentially stimulate pelagic BP. However, exploitation of benthic OC probably is suboptimal because of nutrient limitation (primarily by inorganic P) of BP.\n
\n\n\n\n \n\n \n \n \n \n \n \n Integrating carbon emissions from lakes and streams in a subarctic catchment.\n \n \n \n \n\n\n \n Lundin, E. J.; Giesler, R.; Persson, A.; Thompson, M. S.; and Karlsson, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 118(3): 1200–1207. July 2013.\n \n\n\n\n
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\n\n\n@article{lundin_integrating_2013,\n\ttitle = {Integrating carbon emissions from lakes and streams in a subarctic catchment},\n\tvolume = {118},\n\tissn = {2169-8961},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20092/abstract},\n\tdoi = {10.1002/jgrg.20092},\n\tabstract = {Northern inland waters emit CO2 and CH4 to the atmosphere but the importance of these emissions is poorly understood due to a lack of integrated catchment-scale estimates of carbon (C) emissions from lakes and streams. In this study we quantified the annual emission of CO2 and CH4 from 27 lakes and 23 stream segments in a 15 km2 subarctic catchment in northern Sweden. All lakes and streams were net sources of C to the atmosphere on an annual basis. Streams dominated (96\\%) the aquatic CO2 emission while lakes (61\\%) dominated the aquatic CH4 emission. Total aquatic C emission from the catchment was estimated to be 9.1 g C m−2 yr−1 (98\\% as CO2). Although streams only accounted for 4\\% of the aquatic area in the catchment, they accounted for 95\\% of the total emission. The C emissions from lakes and streams were considerably larger than previously reported downstream waterborne export of C from the catchment, indicating that the atmospheric losses of C in the aquatic systems are an important component in the catchment C balance.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-06},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Lundin, Erik J. and Giesler, Reiner and Persson, Andreas and Thompson, Megan S. and Karlsson, Jan},\n\tmonth = jul,\n\tyear = {2013},\n\tkeywords = {\\#nosource, 0315 Biosphere/atmosphere interactions, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, 0458 Limnology, 1832 Groundwater transport, Biogeochemical cycles, processes, and modeling, Biosphere/atmosphere interactions, CH4, CO2, Groundwater transport, Limnology, carbon cycling, emission, lakes, streams, subarctic},\n\tpages = {1200--1207},\n}\n\n\n\n\n\n Northern inland waters emit CO2 and CH4 to the atmosphere but the importance of these emissions is poorly understood due to a lack of integrated catchment-scale estimates of carbon (C) emissions from lakes and streams. In this study we quantified the annual emission of CO2 and CH4 from 27 lakes and 23 stream segments in a 15 km2 subarctic catchment in northern Sweden. All lakes and streams were net sources of C to the atmosphere on an annual basis. Streams dominated (96%) the aquatic CO2 emission while lakes (61%) dominated the aquatic CH4 emission. Total aquatic C emission from the catchment was estimated to be 9.1 g C m−2 yr−1 (98% as CO2). Although streams only accounted for 4% of the aquatic area in the catchment, they accounted for 95% of the total emission. The C emissions from lakes and streams were considerably larger than previously reported downstream waterborne export of C from the catchment, indicating that the atmospheric losses of C in the aquatic systems are an important component in the catchment C balance.\n
\n\n\n\n \n\n \n \n \n \n \n \n Variable temperature effects of Open Top Chambers at polar and alpine sites explained by irradiance and snow depth.\n \n \n \n \n\n\n \n Bokhorst, S.; Huiskes, A.; Aerts, R.; Convey, P.; Cooper, E. J.; Dalen, L.; Erschbamer, B.; Gudmundsson, J.; Hofgaard, A.; Hollister, R. D.; Johnstone, J.; Jónsdóttir, I. S.; Lebouvier, M.; Van de Vijver, B.; Wahren, C.; and Dorrepaal, E.\n\n\n \n\n\n\n Global Change Biology, 19(1): 64–74. January 2013.\n \n\n\n\n
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\n\n\n@article{bokhorst_variable_2013,\n\ttitle = {Variable temperature effects of {Open} {Top} {Chambers} at polar and alpine sites explained by irradiance and snow depth},\n\tvolume = {19},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.12028/abstract},\n\tdoi = {10.1111/gcb.12028},\n\tabstract = {Environmental manipulation studies are integral to determining biological consequences of climate warming. Open Top Chambers (OTCs) have been widely used to assess summer warming effects on terrestrial biota, with their effects during other seasons normally being given less attention even though chambers are often deployed year-round. In addition, their effects on temperature extremes and freeze-thaw events are poorly documented. To provide robust documentation of the microclimatic influences of OTCs throughout the year, we analysed temperature data from 20 studies distributed across polar and alpine regions. The effects of OTCs on mean temperature showed a large range (−0.9 to 2.1 °C) throughout the year, but did not differ significantly between studies. Increases in mean monthly and diurnal temperature were strongly related (R2 = 0.70) with irradiance, indicating that PAR can be used to predict the mean warming effect of OTCs. Deeper snow trapped in OTCs also induced higher temperatures at soil/vegetation level. OTC-induced changes in the frequency of freeze-thaw events included an increase in autumn and decreases in spring and summer. Frequency of high-temperature events in OTCs increased in spring, summer and autumn compared with non-manipulated control plots. Frequency of low-temperature events was reduced by deeper snow accumulation and higher mean temperatures. The strong interactions identified between aspects of ambient environmental conditions and effects of OTCs suggest that a detailed knowledge of snow depth, temperature and irradiance levels enables us to predict how OTCs will modify the microclimate at a particular site and season. Such predictive power allows a better mechanistic understanding of observed biotic response to experimental warming studies and for more informed design of future experiments. However, a need remains to quantify OTC effects on water availability and wind speed (affecting, for example, drying rates and water stress) in combination with microclimate measurements at organism level.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Bokhorst, Stef and Huiskes, Ad and Aerts, Rien and Convey, Peter and Cooper, Elisabeth J. and Dalen, Linda and Erschbamer, Brigitta and Gudmundsson, Jón and Hofgaard, Annika and Hollister, Robert D. and Johnstone, Jill and Jónsdóttir, Ingibjörg S. and Lebouvier, Marc and Van de Vijver, Bart and Wahren, Carl-Henrik and Dorrepaal, Ellen},\n\tmonth = jan,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Antarctic, Arctic, PAR, alpine, climate change, extreme weather, freeze-thaw, snow, temperature variation, tundra, warming experiment, wind},\n\tpages = {64--74},\n}\n\n\n\n\n\n Environmental manipulation studies are integral to determining biological consequences of climate warming. Open Top Chambers (OTCs) have been widely used to assess summer warming effects on terrestrial biota, with their effects during other seasons normally being given less attention even though chambers are often deployed year-round. In addition, their effects on temperature extremes and freeze-thaw events are poorly documented. To provide robust documentation of the microclimatic influences of OTCs throughout the year, we analysed temperature data from 20 studies distributed across polar and alpine regions. The effects of OTCs on mean temperature showed a large range (−0.9 to 2.1 °C) throughout the year, but did not differ significantly between studies. Increases in mean monthly and diurnal temperature were strongly related (R2 = 0.70) with irradiance, indicating that PAR can be used to predict the mean warming effect of OTCs. Deeper snow trapped in OTCs also induced higher temperatures at soil/vegetation level. OTC-induced changes in the frequency of freeze-thaw events included an increase in autumn and decreases in spring and summer. Frequency of high-temperature events in OTCs increased in spring, summer and autumn compared with non-manipulated control plots. Frequency of low-temperature events was reduced by deeper snow accumulation and higher mean temperatures. The strong interactions identified between aspects of ambient environmental conditions and effects of OTCs suggest that a detailed knowledge of snow depth, temperature and irradiance levels enables us to predict how OTCs will modify the microclimate at a particular site and season. Such predictive power allows a better mechanistic understanding of observed biotic response to experimental warming studies and for more informed design of future experiments. However, a need remains to quantify OTC effects on water availability and wind speed (affecting, for example, drying rates and water stress) in combination with microclimate measurements at organism level.\n
\n\n\n\n \n\n \n \n \n \n \n \n High emission of carbon dioxide and methane during ice thaw in high latitude lakes.\n \n \n \n \n\n\n \n Karlsson, J.; Giesler, R.; Persson, J.; and Lundin, E.\n\n\n \n\n\n\n Geophysical Research Letters, 40(6): 1123–1127. March 2013.\n 00040\n\n\n\n
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\n\n\n@article{karlsson_high_2013,\n\ttitle = {High emission of carbon dioxide and methane during ice thaw in high latitude lakes},\n\tvolume = {40},\n\tissn = {1944-8007},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/grl.50152/abstract},\n\tdoi = {10.1002/grl.50152},\n\tabstract = {The winter period is seldom included in the estimates of aquatic-atmospheric carbon exchange. In this study we quantified the flux of carbon dioxide (CO2) and methane (CH4) over 3 years from 12 small subarctic lakes. The lakes accumulated consistent and high amounts of CO2 and CH4 (56–97\\% as CO2) over the winter, resulting in a high flux during ice thaw. The CO2 flux during ice thaw increased with increasing mean depth of the lakes, while the CH4 flux was high in lakes surrounded by mires. The ice thaw period was quantitatively important to the annual gas balances of the lakes. For nine of the lakes, 11 to 55\\% of the annual flux occurred during thaw. For three of the lakes with an apparent net annual CO2 uptake, including the thaw period reversed the balance from sink to source. Our results suggest that the ice thaw period is critically important for the emissions of CO2 and CH4 in small lakes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-06},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Karlsson, Jan and Giesler, Reiner and Persson, Jenny and Lundin, Erik},\n\tmonth = mar,\n\tyear = {2013},\n\tnote = {00040},\n\tkeywords = {\\#nosource, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, 0458 Limnology, 0475 Permafrost, cryosphere, and high-latitude processes, 0490 Trace gases, Biogeochemical cycles, processes, and modeling, Limnology, Permafrost, cryosphere, and high-latitude processes, Trace gases, carbon cycling, carbon fluxes, lakes, winter},\n\tpages = {1123--1127},\n}\n\n\n\n\n\n The winter period is seldom included in the estimates of aquatic-atmospheric carbon exchange. In this study we quantified the flux of carbon dioxide (CO2) and methane (CH4) over 3 years from 12 small subarctic lakes. The lakes accumulated consistent and high amounts of CO2 and CH4 (56–97% as CO2) over the winter, resulting in a high flux during ice thaw. The CO2 flux during ice thaw increased with increasing mean depth of the lakes, while the CH4 flux was high in lakes surrounded by mires. The ice thaw period was quantitatively important to the annual gas balances of the lakes. For nine of the lakes, 11 to 55% of the annual flux occurred during thaw. For three of the lakes with an apparent net annual CO2 uptake, including the thaw period reversed the balance from sink to source. Our results suggest that the ice thaw period is critically important for the emissions of CO2 and CH4 in small lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Spatiotemporal variations of pCO2 and δ13C-DIC in subarctic streams in northern Sweden.\n \n \n \n \n\n\n \n Giesler, R.; Mörth, C.; Karlsson, J.; Lundin, E. J.; Lyon, S. W.; and Humborg, C.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 27(1): 176–186. March 2013.\n 00009\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{giesler_spatiotemporal_2013,\n\ttitle = {Spatiotemporal variations of {pCO2} and δ{13C}-{DIC} in subarctic streams in northern {Sweden}},\n\tvolume = {27},\n\tissn = {1944-9224},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/gbc.20024/abstract},\n\tdoi = {10.1002/gbc.20024},\n\tabstract = {Current predictions of climate-related changes in high-latitude environments suggest major effects on the C export in streams and rivers. To what extent this will also affect the stream water CO2 concentrations is poorly understood. In this study we examined the spatiotemporal variation in partial pressure of CO2 (pCO2) and in stable isotopic composition of dissolved inorganic carbon (δ13C-DIC) in subarctic streams in northern Sweden. The selected watersheds are characterized by large variations in high-latitude boreal forest and tundra and differences in bedrock. We found that all streams generally were supersaturated in pCO2 with an average concentration of 850 µatm. The variability in pCO2 across streams was poorly related to vegetation cover, and carbonaceous bedrock influence was manifested in high DIC concentrations but not reflected in either stream pCO2 or δ13C-DIC. Stream water pCO2 values were highest during winter base flow when we also observed the lowest δ13C-DIC values, and this pattern is interpreted as a high contribution from CO2 from soil respiration. Summer base flow δ13C-DIC values probably are more affected by in situ stream processes such as aquatic production/respiration and degassing. A challenge for further studies will be to disentangle the origin of stream water CO2 and quantify their relative importance.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-06},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Giesler, Reiner and Mörth, Carl-Magnus and Karlsson, Jan and Lundin, Erik J. and Lyon, Steve W. and Humborg, Christoph},\n\tmonth = mar,\n\tyear = {2013},\n\tnote = {00009},\n\tkeywords = {\\#nosource, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, Biogeochemical cycles, processes, and modeling, carbon cycling, high-latitude, stream, tundra, δ13C-DIC},\n\tpages = {176--186},\n}\n\n\n\n\n\n Current predictions of climate-related changes in high-latitude environments suggest major effects on the C export in streams and rivers. To what extent this will also affect the stream water CO2 concentrations is poorly understood. In this study we examined the spatiotemporal variation in partial pressure of CO2 (pCO2) and in stable isotopic composition of dissolved inorganic carbon (δ13C-DIC) in subarctic streams in northern Sweden. The selected watersheds are characterized by large variations in high-latitude boreal forest and tundra and differences in bedrock. We found that all streams generally were supersaturated in pCO2 with an average concentration of 850 µatm. The variability in pCO2 across streams was poorly related to vegetation cover, and carbonaceous bedrock influence was manifested in high DIC concentrations but not reflected in either stream pCO2 or δ13C-DIC. Stream water pCO2 values were highest during winter base flow when we also observed the lowest δ13C-DIC values, and this pattern is interpreted as a high contribution from CO2 from soil respiration. Summer base flow δ13C-DIC values probably are more affected by in situ stream processes such as aquatic production/respiration and degassing. A challenge for further studies will be to disentangle the origin of stream water CO2 and quantify their relative importance.\n
\n\n\n\n \n\n \n \n \n \n \n \n Nitrogen deposition and warming – effects on phytoplankton nutrient limitation in subarctic lakes.\n \n \n \n \n\n\n \n Bergström, A.; Faithfull, C.; Karlsson, D.; and Karlsson, J.\n\n\n \n\n\n\n Global Change Biology, 19(8): 2557–2568. August 2013.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{bergstrom_nitrogen_2013,\n\ttitle = {Nitrogen deposition and warming – effects on phytoplankton nutrient limitation in subarctic lakes},\n\tvolume = {19},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.12234/abstract},\n\tdoi = {10.1111/gcb.12234},\n\tabstract = {The aim of this study was to predict the combined effects of enhanced nitrogen (N) deposition and warming on phytoplankton development in high latitude and mountain lakes. Consequently, we assessed, in a series of enclosure experiments, how lake water nutrient stoichiometry and phytoplankton nutrient limitation varied over the growing season in 11 lakes situated along an altitudinal/climate gradient with low N-deposition ({\\textless}1 kg N ha−1 yr−1) in northern subarctic Sweden. Short-term bioassay experiments with N- and P-additions revealed that phytoplankton in high-alpine lakes were more prone to P-limitation, and with decreasing altitude became increasingly N- and NP-colimited. Nutrient limitation was additionally most obvious in midsummer. There was also a strong positive correlation between phytoplankton growth and water temperature in the bioassays. Although excess nutrients were available in spring and autumn, on these occasions growth was likely constrained by low water temperatures. These results imply that enhanced N-deposition over the Swedish mountain areas will, with the exception of high-alpine lakes, enhance biomass and drive phytoplankton from N- to P-limitation. However, if not accompanied by warming, N-input from deposition will stimulate limited phytoplankton growth due to low water temperatures during large parts of the growing season. Direct effects of warming, allowing increased metabolic rates and an extension of the growing season, seem equally crucial to synergistically enhance phytoplankton development in these lakes.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2017-02-06},\n\tjournal = {Global Change Biology},\n\tauthor = {Bergström, Ann-Kristin and Faithfull, Carolyn and Karlsson, Daniel and Karlsson, Jan},\n\tmonth = aug,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Nitrogen, atmospheric deposition, chlorophyll, growing season, phosphorus, water temperature},\n\tpages = {2557--2568},\n}\n\n\n\n\n\n The aim of this study was to predict the combined effects of enhanced nitrogen (N) deposition and warming on phytoplankton development in high latitude and mountain lakes. Consequently, we assessed, in a series of enclosure experiments, how lake water nutrient stoichiometry and phytoplankton nutrient limitation varied over the growing season in 11 lakes situated along an altitudinal/climate gradient with low N-deposition (\\textless1 kg N ha−1 yr−1) in northern subarctic Sweden. Short-term bioassay experiments with N- and P-additions revealed that phytoplankton in high-alpine lakes were more prone to P-limitation, and with decreasing altitude became increasingly N- and NP-colimited. Nutrient limitation was additionally most obvious in midsummer. There was also a strong positive correlation between phytoplankton growth and water temperature in the bioassays. Although excess nutrients were available in spring and autumn, on these occasions growth was likely constrained by low water temperatures. These results imply that enhanced N-deposition over the Swedish mountain areas will, with the exception of high-alpine lakes, enhance biomass and drive phytoplankton from N- to P-limitation. However, if not accompanied by warming, N-input from deposition will stimulate limited phytoplankton growth due to low water temperatures during large parts of the growing season. Direct effects of warming, allowing increased metabolic rates and an extension of the growing season, seem equally crucial to synergistically enhance phytoplankton development in these lakes.\n
\n\n\n\n \n\n \n \n \n \n \n Traits underpinning desiccation resistance explain distribution patterns of terrestrial isopods.\n \n \n \n\n\n \n Dias, A. T. C.; Krab, E. J.; Mariën, J.; Zimmer, M.; Cornelissen, J. H. C.; Ellers, J.; Wardle, D. A.; and Berg, M. P.\n\n\n \n\n\n\n Oecologia, 172(3): 667–677. July 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{dias_traits_2013,\n\ttitle = {Traits underpinning desiccation resistance explain distribution patterns of terrestrial isopods},\n\tvolume = {172},\n\tissn = {1432-1939},\n\tdoi = {10.1007/s00442-012-2541-3},\n\tabstract = {Predicted changes in soil water availability regimes with climate and land-use change will impact the community of functionally important soil organisms, such as macro-detritivores. Identifying and quantifying the functional traits that underlie interspecific differences in desiccation resistance will enhance our ability to predict both macro-detritivore community responses to changing water regimes and the consequences of the associated species shifts for organic matter turnover. Using path analysis, we tested (1) how interspecific differences in desiccation resistance among 22 northwestern European terrestrial isopod species could be explained by three underlying traits measured under standard laboratory conditions, namely, body ventral surface area, water loss rate and fatal water loss; (2) whether these relationships were robust to contrasting experimental conditions and to the phylogenetic relatedness effects being excluded; (3) whether desiccation resistance and hypothesized underlying traits could explain species distribution patterns in relation to site water availability. Water loss rate and (secondarily) fatal water loss together explained 90\\% of the interspecific variation in desiccation resistance. Our path model indicated that body surface area affects desiccation resistance only indirectly via changes in water loss rate. Our results also show that soil moisture determines isopod species distributions by filtering them according to traits underpinning desiccation resistance. These findings reveal that it is possible to use functional traits measured under standard conditions to predict soil biota responses to water availability in the field over broad spatial scales. Taken together, our results demonstrate an increasing need to generate mechanistic models to predict the effect of global changes on functionally important organisms.},\n\tlanguage = {eng},\n\tnumber = {3},\n\tjournal = {Oecologia},\n\tauthor = {Dias, André T. C. and Krab, Eveline J. and Mariën, Janine and Zimmer, Martin and Cornelissen, Johannes H. C. and Ellers, Jacintha and Wardle, David A. and Berg, Matty P.},\n\tmonth = jul,\n\tyear = {2013},\n\tpmid = {23224790},\n\tkeywords = {\\#nosource, Animals, Droughts, Europe, Isopoda, Species Specificity, climate},\n\tpages = {667--677},\n}\n\n\n\n\n\n Predicted changes in soil water availability regimes with climate and land-use change will impact the community of functionally important soil organisms, such as macro-detritivores. Identifying and quantifying the functional traits that underlie interspecific differences in desiccation resistance will enhance our ability to predict both macro-detritivore community responses to changing water regimes and the consequences of the associated species shifts for organic matter turnover. Using path analysis, we tested (1) how interspecific differences in desiccation resistance among 22 northwestern European terrestrial isopod species could be explained by three underlying traits measured under standard laboratory conditions, namely, body ventral surface area, water loss rate and fatal water loss; (2) whether these relationships were robust to contrasting experimental conditions and to the phylogenetic relatedness effects being excluded; (3) whether desiccation resistance and hypothesized underlying traits could explain species distribution patterns in relation to site water availability. Water loss rate and (secondarily) fatal water loss together explained 90% of the interspecific variation in desiccation resistance. Our path model indicated that body surface area affects desiccation resistance only indirectly via changes in water loss rate. Our results also show that soil moisture determines isopod species distributions by filtering them according to traits underpinning desiccation resistance. These findings reveal that it is possible to use functional traits measured under standard conditions to predict soil biota responses to water availability in the field over broad spatial scales. Taken together, our results demonstrate an increasing need to generate mechanistic models to predict the effect of global changes on functionally important organisms.\n
\n\n\n\n \n\n \n \n \n \n \n Phenolic Responses of Mountain Crowberry (Empetrum nigrum ssp hermaphroditum) to Global Climate Change are Compound Specific and Depend on Grazing by Reindeer (Rangifer tarandus).\n \n \n \n\n\n \n Väisänen, M.; Martz, F.; Kaarlejärvi, E.; Julkunen-Tiitto, R.; and Stark, S.\n\n\n \n\n\n\n Journal of Chemical Ecology, 39(11-12): 1390–1399. December 2013.\n 00008\n\n\n\n
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\n\n\n@article{vaisanen_phenolic_2013,\n\ttitle = {Phenolic {Responses} of {Mountain} {Crowberry} ({Empetrum} nigrum ssp hermaphroditum) to {Global} {Climate} {Change} are {Compound} {Specific} and {Depend} on {Grazing} by {Reindeer} ({Rangifer} tarandus)},\n\tvolume = {39},\n\tissn = {0098-0331},\n\tdoi = {10.1007/s10886-013-0367-z},\n\tabstract = {Mountain crowberry (Empetrum nigrum ssp. hermaphroditum) is a keystone species in northern ecosystems and exerts important ecosystem-level effects through high concentrations of phenolic metabolites. It has not been investigated how crowberry phenolics will respond to global climate change. In the tundra, grazing by reindeer (Rangifer tarandus) affects vegetation and soil nutrient availability, but almost nothing is known about the interactions between grazing and global climate change on plant phenolics. We performed a factorial warming and fertilization experiment in a tundra ecosystem under light grazing and heavy grazing and analyzed individual foliar phenolics and crowberry abundance. Crowberry was more abundant under light grazing than heavy grazing. Although phenolic concentrations did not differ between grazing intensities, responses of crowberry abundance and phenolic concentrations to warming varied significantly depending on grazing intensity. Under light grazing, warming increased crowberry abundance and the concentration of stilbenes, but decreased e.g., the concentrations of flavonols, condensed tannins, and batatasin-III, resulting in no change in total phenolics. Under heavy grazing, warming did not affect crowberry abundance, and induced a weak but consistent decrease among the different phenolic compound groups, resulting in a net decrease in total phenolics. Our results show that the different phenolic compound groups may show varying or even opposing responses to warming in the tundra at different levels of grazing intensity. Even when plant phenolic concentrations do not directly respond to grazing, grazers may have a key control over plant responses to changes in the abiotic environment, reflecting multiple adaptive purposes of plant phenolics and complex interactions between the biotic and the abiotic factors.},\n\tlanguage = {English},\n\tnumber = {11-12},\n\tjournal = {Journal of Chemical Ecology},\n\tauthor = {Väisänen, Maria and Martz, Francoise and Kaarlejärvi, Elina and Julkunen-Tiitto, Riitta and Stark, Sari},\n\tmonth = dec,\n\tyear = {2013},\n\tnote = {00008},\n\tkeywords = {\\#nosource, Batatasin-III, Plants, Stilbenes, Warming, allocation, arctic tundra, carbon-nutrient balance, dwarf shrubs, fertilization, growth, herbivores, herbivory, tannins, tundra ecosystems, vegetation},\n\tpages = {1390--1399},\n}\n\n\n\n\n\n Mountain crowberry (Empetrum nigrum ssp. hermaphroditum) is a keystone species in northern ecosystems and exerts important ecosystem-level effects through high concentrations of phenolic metabolites. It has not been investigated how crowberry phenolics will respond to global climate change. In the tundra, grazing by reindeer (Rangifer tarandus) affects vegetation and soil nutrient availability, but almost nothing is known about the interactions between grazing and global climate change on plant phenolics. We performed a factorial warming and fertilization experiment in a tundra ecosystem under light grazing and heavy grazing and analyzed individual foliar phenolics and crowberry abundance. Crowberry was more abundant under light grazing than heavy grazing. Although phenolic concentrations did not differ between grazing intensities, responses of crowberry abundance and phenolic concentrations to warming varied significantly depending on grazing intensity. Under light grazing, warming increased crowberry abundance and the concentration of stilbenes, but decreased e.g., the concentrations of flavonols, condensed tannins, and batatasin-III, resulting in no change in total phenolics. Under heavy grazing, warming did not affect crowberry abundance, and induced a weak but consistent decrease among the different phenolic compound groups, resulting in a net decrease in total phenolics. Our results show that the different phenolic compound groups may show varying or even opposing responses to warming in the tundra at different levels of grazing intensity. Even when plant phenolic concentrations do not directly respond to grazing, grazers may have a key control over plant responses to changes in the abiotic environment, reflecting multiple adaptive purposes of plant phenolics and complex interactions between the biotic and the abiotic factors.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant–herbivore–decomposer stoichiometric mismatches and nutrient cycling in ecosystems.\n \n \n \n \n\n\n \n Cherif, M.; and Loreau, M.\n\n\n \n\n\n\n Proc. R. Soc. B, 280(1754): 20122453. March 2013.\n \n\n\n\n
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\n\n\n@article{cherif_plantherbivoredecomposer_2013,\n\ttitle = {Plant–herbivore–decomposer stoichiometric mismatches and nutrient cycling in ecosystems},\n\tvolume = {280},\n\tcopyright = {© 2013 The Author(s) Published by the Royal Society. All rights reserved.},\n\tissn = {0962-8452, 1471-2954},\n\turl = {http://rspb.royalsocietypublishing.org/content/280/1754/20122453},\n\tdoi = {10.1098/rspb.2012.2453},\n\tabstract = {Plant stoichiometry is thought to have a major influence on how herbivores affect nutrient availability in ecosystems. Most conceptual models predict that plants with high nutrient contents increase nutrient excretion by herbivores, in turn raising nutrient availability. To test this hypothesis, we built a stoichiometrically explicit model that includes a simple but thorough description of the processes of herbivory and decomposition. Our results challenge traditional views of herbivore impacts on nutrient availability in many ways. They show that the relationship between plant nutrient content and the impact of herbivores predicted by conceptual models holds only at high plant nutrient contents. At low plant nutrient contents, the impact of herbivores is mediated by the mineralization/immobilization of nutrients by decomposers and by the type of resource limiting the growth of decomposers. Both parameters are functions of the mismatch between plant and decomposer stoichiometries. Our work provides new predictions about the impacts of herbivores on ecosystem fertility that depend on critical interactions between plant, herbivore and decomposer stoichiometries in ecosystems.},\n\tlanguage = {en},\n\tnumber = {1754},\n\turldate = {2017-05-27},\n\tjournal = {Proc. R. Soc. B},\n\tauthor = {Cherif, Mehdi and Loreau, Michel},\n\tmonth = mar,\n\tyear = {2013},\n\tpmid = {23303537},\n\tkeywords = {\\#nosource},\n\tpages = {20122453},\n}\n\n\n\n\n\n Plant stoichiometry is thought to have a major influence on how herbivores affect nutrient availability in ecosystems. Most conceptual models predict that plants with high nutrient contents increase nutrient excretion by herbivores, in turn raising nutrient availability. To test this hypothesis, we built a stoichiometrically explicit model that includes a simple but thorough description of the processes of herbivory and decomposition. Our results challenge traditional views of herbivore impacts on nutrient availability in many ways. They show that the relationship between plant nutrient content and the impact of herbivores predicted by conceptual models holds only at high plant nutrient contents. At low plant nutrient contents, the impact of herbivores is mediated by the mineralization/immobilization of nutrients by decomposers and by the type of resource limiting the growth of decomposers. Both parameters are functions of the mismatch between plant and decomposer stoichiometries. Our work provides new predictions about the impacts of herbivores on ecosystem fertility that depend on critical interactions between plant, herbivore and decomposer stoichiometries in ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Summer CO2 evasion from streams and rivers in the Kolyma River basin, north-east Siberia.\n \n \n \n \n\n\n \n Denfeld, B. A.; Frey, K. E.; Sobczak, W. V.; Mann, P. J.; and Holmes, R. M.\n\n\n \n\n\n\n Polar Research, 32(1): 19704. January 2013.\n \n\n\n\n
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\n\n\n@article{denfeld_summer_2013,\n\ttitle = {Summer {CO2} evasion from streams and rivers in the {Kolyma} {River} basin, north-east {Siberia}},\n\tvolume = {32},\n\tissn = {null},\n\turl = {http://dx.doi.org/10.3402/polar.v32i0.19704},\n\tdoi = {10.3402/polar.v32i0.19704},\n\tabstract = {Inland water systems are generally supersaturated in carbon dioxide (CO2) and are increasingly recognized as playing an important role in the global carbon cycle. The Arctic may be particularly important in this respect, given the abundance of inland waters and carbon contained in Arctic soils; however, a lack of trace gas measurements from small streams in the Arctic currently limits this understanding. We investigated the spatial variability of CO2 evasion during the summer low-flow period from streams and rivers in the northern portion of the Kolyma River basin in north-eastern Siberia. To this end, partial pressure of carbon dioxide (pCO2) and gas exchange velocities (k) were measured at a diverse set of streams and rivers to calculate CO2 evasion fluxes. We combined these CO2 evasion estimates with satellite remote sensing and geographic information system techniques to calculate total areal CO2 emissions. Our results show that small streams are substantial sources of atmospheric CO2 owing to high pCO2 and k, despite being a small portion of total inland water surface area. In contrast, large rivers were generally near equilibrium with atmospheric CO2. Extrapolating our findings across the Panteleikha–Ambolikha sub-watersheds demonstrated that small streams play a major role in CO2 evasion, accounting for 86\\% of the total summer CO2 emissions from inland waters within these two sub-watersheds. Further expansion of these regional CO2 emission estimates across time and space will be critical to accurately quantify and understand the role of Arctic streams and rivers in the global carbon budget.},\n\tnumber = {1},\n\turldate = {2017-05-27},\n\tjournal = {Polar Research},\n\tauthor = {Denfeld, Blaize A. and Frey, Karen E. and Sobczak, William V. and Mann, Paul J. and Holmes, Robert M.},\n\tmonth = jan,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Arctic streams and rivers, CO2 evasion, Kolyma River, inland water surface area, pCO2, siberia},\n\tpages = {19704},\n}\n\n\n\n\n\n Inland water systems are generally supersaturated in carbon dioxide (CO2) and are increasingly recognized as playing an important role in the global carbon cycle. The Arctic may be particularly important in this respect, given the abundance of inland waters and carbon contained in Arctic soils; however, a lack of trace gas measurements from small streams in the Arctic currently limits this understanding. We investigated the spatial variability of CO2 evasion during the summer low-flow period from streams and rivers in the northern portion of the Kolyma River basin in north-eastern Siberia. To this end, partial pressure of carbon dioxide (pCO2) and gas exchange velocities (k) were measured at a diverse set of streams and rivers to calculate CO2 evasion fluxes. We combined these CO2 evasion estimates with satellite remote sensing and geographic information system techniques to calculate total areal CO2 emissions. Our results show that small streams are substantial sources of atmospheric CO2 owing to high pCO2 and k, despite being a small portion of total inland water surface area. In contrast, large rivers were generally near equilibrium with atmospheric CO2. Extrapolating our findings across the Panteleikha–Ambolikha sub-watersheds demonstrated that small streams play a major role in CO2 evasion, accounting for 86% of the total summer CO2 emissions from inland waters within these two sub-watersheds. Further expansion of these regional CO2 emission estimates across time and space will be critical to accurately quantify and understand the role of Arctic streams and rivers in the global carbon budget.\n
\n\n\n\n \n\n \n \n \n \n \n \n Cross-ecosystem differences in lipid composition and growth limitation of a benthic generalist consumer.\n \n \n \n \n\n\n \n Lau, D. C. P.; Goedkoop, W.; and Vrede, T.\n\n\n \n\n\n\n Limnology and Oceanography, 58(4): 1149–1164. July 2013.\n 00017\n\n\n\n
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\n\n\n@article{lau_cross-ecosystem_2013,\n\ttitle = {Cross-ecosystem differences in lipid composition and growth limitation of a benthic generalist consumer},\n\tvolume = {58},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.4319/lo.2013.58.4.1149/abstract},\n\tdoi = {10.4319/lo.2013.58.4.1149},\n\tabstract = {In a field study, we analyzed the fatty acid (FA) composition of the benthic generalist Asellus aquaticus collected from boreal lakes, ponds, and streams across gradients in ambient nutrient levels. In laboratory feeding experiments, we tested the diet-quality and seasonal effects on somatic growth and FAs of spring- and autumn-collected Asellus that were fed four different diets containing increasing concentrations of polyunsaturated FAs (PUFA): conditioned leaf litter, algal flakes, mixed litter and algal flakes (Mixed), or Mixed plus fish-food flakes. Ambient nutrients were strong determinants of FA variation of field Asellus, explaining {\\textgreater} 44\\% in total. The ratios of eicosapentaenoic acid (EPA) to total FAs, EPA : ω3, and ω3 : ω6 of Asellus increased up to four times with increasing trophic state and decreasing humic matter content, likely because dietary ω3 FAs were more prevalent in benthic habitats of eutrophic than of oligotrophic systems. In the feeding trials, growth of Asellus collected in both seasons was markedly lower on leaf litter than on higher PUFA diets. However, autumn-collected Asellus fed a Mixed or Mixed+fish-food diet grew 3–10 times faster, but retained {\\textless} 50\\% EPA and PUFA than spring counterparts. Asellus optimized PUFA accumulation in spring but somatic growth in autumn. Our field survey suggests ambient nutrient concentrations modify dietary PUFA supply from basal resources, while laboratory studies show that growth response and PUFA accumulation of Asellus differ between seasons, likely due to its season-specific physiological status and diet quality. An increase in nutrients will release benthic consumers from growth limitation and favor more efficient trophic transfer.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-05-27},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Lau, Danny C. P. and Goedkoop, Willem and Vrede, Tobias},\n\tmonth = jul,\n\tyear = {2013},\n\tnote = {00017},\n\tkeywords = {\\#nosource},\n\tpages = {1149--1164},\n}\n\n\n\n\n\n In a field study, we analyzed the fatty acid (FA) composition of the benthic generalist Asellus aquaticus collected from boreal lakes, ponds, and streams across gradients in ambient nutrient levels. In laboratory feeding experiments, we tested the diet-quality and seasonal effects on somatic growth and FAs of spring- and autumn-collected Asellus that were fed four different diets containing increasing concentrations of polyunsaturated FAs (PUFA): conditioned leaf litter, algal flakes, mixed litter and algal flakes (Mixed), or Mixed plus fish-food flakes. Ambient nutrients were strong determinants of FA variation of field Asellus, explaining \\textgreater 44% in total. The ratios of eicosapentaenoic acid (EPA) to total FAs, EPA : ω3, and ω3 : ω6 of Asellus increased up to four times with increasing trophic state and decreasing humic matter content, likely because dietary ω3 FAs were more prevalent in benthic habitats of eutrophic than of oligotrophic systems. In the feeding trials, growth of Asellus collected in both seasons was markedly lower on leaf litter than on higher PUFA diets. However, autumn-collected Asellus fed a Mixed or Mixed+fish-food diet grew 3–10 times faster, but retained \\textless 50% EPA and PUFA than spring counterparts. Asellus optimized PUFA accumulation in spring but somatic growth in autumn. Our field survey suggests ambient nutrient concentrations modify dietary PUFA supply from basal resources, while laboratory studies show that growth response and PUFA accumulation of Asellus differ between seasons, likely due to its season-specific physiological status and diet quality. An increase in nutrients will release benthic consumers from growth limitation and favor more efficient trophic transfer.\n
\n\n\n\n \n\n \n \n \n \n \n \n Physical mixing between humus and mineral matter found in cryoturbated soils increases short-term heterotrophic respiration rates.\n \n \n \n \n\n\n \n Klaminder, J.; Giesler, R.; and Makoto, K.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 57: 922–924. February 2013.\n \n\n\n\n
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\n\n\n@article{klaminder_physical_2013,\n\ttitle = {Physical mixing between humus and mineral matter found in cryoturbated soils increases short-term heterotrophic respiration rates},\n\tvolume = {57},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071712004178},\n\tdoi = {10.1016/j.soilbio.2012.10.038},\n\tabstract = {Cryoturbation is an important mechanism in the most recent large-scale model describing the build-up of soil organic carbon (SOC) in arctic soils. In this paper, we hypothesize that the physical mixing of humus and mineral soil generated by this process causes previously unconsidered effects on respiration rates. Through laboratory incubations we found that mixing of humus into mineral soil from cryoturbated soils primed heterotrophic respiration rates by about 40\\%, which was of the same magnitude as the effect generated by a rise in soil temperature from 5 °C to 10 °C. Our result indicates that cryogenic mixing, if complete, may generate short-term positive effects on heterotrophic respiration rates as long as the mixing does not translocate carbon into much colder soil layers.},\n\turldate = {2017-02-07},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Klaminder, J. and Giesler, R. and Makoto, K.},\n\tmonth = feb,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Arctic, Cryoturbation, Heterotrophic respiration rates, Soil},\n\tpages = {922--924},\n}\n\n\n\n\n\n Cryoturbation is an important mechanism in the most recent large-scale model describing the build-up of soil organic carbon (SOC) in arctic soils. In this paper, we hypothesize that the physical mixing of humus and mineral soil generated by this process causes previously unconsidered effects on respiration rates. Through laboratory incubations we found that mixing of humus into mineral soil from cryoturbated soils primed heterotrophic respiration rates by about 40%, which was of the same magnitude as the effect generated by a rise in soil temperature from 5 °C to 10 °C. Our result indicates that cryogenic mixing, if complete, may generate short-term positive effects on heterotrophic respiration rates as long as the mixing does not translocate carbon into much colder soil layers.\n
\n\n\n\n \n\n \n \n \n \n \n \n CARD-FISH analysis of prokaryotic community composition and abundance along small-scale vegetation gradients in a dry arctic tundra ecosystem.\n \n \n \n \n\n\n \n Ushio, M.; Makoto, K.; Klaminder, J.; and Nakano, S.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 64: 147–154. September 2013.\n \n\n\n\n
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\n\n\n@article{ushio_card-fish_2013,\n\ttitle = {{CARD}-{FISH} analysis of prokaryotic community composition and abundance along small-scale vegetation gradients in a dry arctic tundra ecosystem},\n\tvolume = {64},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071713001594},\n\tdoi = {10.1016/j.soilbio.2013.05.002},\n\tabstract = {The size and composition of soil microbial communities have important influences on terrestrial ecosystem processes such as soil decomposition. However, compared with studies of aboveground plant communities, there are relatively few studies on belowground microbial communities and their interactions with aboveground vegetations in the arctic region. In this study, we conducted the first investigation of the abundance and composition of prokaryotic communities along small-scale vegetation gradients (ca. 1–3 m) in a dry arctic tundra ecosystem in Northern Sweden using fluorescent in situ hybridization (FISH) coupled with catalyzed reporter deposition (CARD). The number of prokaryotic cells increased with increasing vegetation cover along vegetation gradients, mainly as a function of increased amounts of soil carbon and moisture. Eubacteria and Archaea constituted approximately 59.7\\% and 33.4\\% of DAPI-positive cells, respectively. Among the analyzed bacterial phyla and sub-phyla, Acidobacteria and α-proteobacteria were the most dominant groups, constituting approximately 13.5\\% and 10.7\\% of DAPI-positive cells, respectively. Interestingly, the soil prokaryotic community composition was relatively unaffected by the dramatic changes in the aboveground vegetation community. Multivariate analyses suggested that the prokaryotic community composition depended on soil pH rather than on aboveground vegetation. Surface plants are weak predictors of the composition of the soil microbial community in the studied soil system and the size of the community is constrained by carbon and water availability. In addition, our study demonstrated that CARD-FISH, which is still a rarely-used technique in soil ecology, is effective for quantifying soil microbes.},\n\turldate = {2017-02-07},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Ushio, Masayuki and Makoto, Kobayashi and Klaminder, Jonatan and Nakano, Shin-ichi},\n\tmonth = sep,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Archaea, CARD-FISH, Soil microbial community, Tundra ecosystem, Vegetation gradients, bacteria},\n\tpages = {147--154},\n}\n\n\n\n\n\n The size and composition of soil microbial communities have important influences on terrestrial ecosystem processes such as soil decomposition. However, compared with studies of aboveground plant communities, there are relatively few studies on belowground microbial communities and their interactions with aboveground vegetations in the arctic region. In this study, we conducted the first investigation of the abundance and composition of prokaryotic communities along small-scale vegetation gradients (ca. 1–3 m) in a dry arctic tundra ecosystem in Northern Sweden using fluorescent in situ hybridization (FISH) coupled with catalyzed reporter deposition (CARD). The number of prokaryotic cells increased with increasing vegetation cover along vegetation gradients, mainly as a function of increased amounts of soil carbon and moisture. Eubacteria and Archaea constituted approximately 59.7% and 33.4% of DAPI-positive cells, respectively. Among the analyzed bacterial phyla and sub-phyla, Acidobacteria and α-proteobacteria were the most dominant groups, constituting approximately 13.5% and 10.7% of DAPI-positive cells, respectively. Interestingly, the soil prokaryotic community composition was relatively unaffected by the dramatic changes in the aboveground vegetation community. Multivariate analyses suggested that the prokaryotic community composition depended on soil pH rather than on aboveground vegetation. Surface plants are weak predictors of the composition of the soil microbial community in the studied soil system and the size of the community is constrained by carbon and water availability. In addition, our study demonstrated that CARD-FISH, which is still a rarely-used technique in soil ecology, is effective for quantifying soil microbes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Complex biotic interactions drive long-term vegetation dynamics in a subarctic ecosystem.\n \n \n \n \n\n\n \n Olofsson, J.; Beest, M. t.; and Ericson, L.\n\n\n \n\n\n\n Phil. Trans. R. Soc. B, 368(1624): 20120486. August 2013.\n \n\n\n\n
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\n\n\n@article{olofsson_complex_2013,\n\ttitle = {Complex biotic interactions drive long-term vegetation dynamics in a subarctic ecosystem},\n\tvolume = {368},\n\tcopyright = {© 2013 The Author(s) Published by the Royal Society. All rights reserved.},\n\tissn = {0962-8436, 1471-2970},\n\turl = {http://rstb.royalsocietypublishing.org/content/368/1624/20120486},\n\tdoi = {10.1098/rstb.2012.0486},\n\tabstract = {Predicting impacts of global warming requires understanding of the extent to which plant biomass and production are controlled by bottom-up and top-down drivers. By annually monitoring community composition in grazed control plots and herbivore-free exclosures at an Arctic location for 15 years, we detected multiple biotic interactions. Regular rodent cycles acted as pulses driving synchronous fluctuations in the biomass of field-layer vegetation; reindeer influenced the biomass of taller shrubs, and the abundance of plant pathogenic fungi increased when densities of their host plants increased in exclosures. Two outbreaks of geometrid moths occurred during the study period, with contrasting effects on the field layer: one in 2004 had marginal effects, while one in 2012 severely reduced biomass in the control plots and eliminated biomass that had accumulated over 15 years in the exclosures. The latter was followed by a dramatic decline of the dominant understory dwarf-shrub Empetrum hermaphroditum, driven by an interaction between moth herbivory on top buds and leaves, and increased disease severity of a pathogenic fungus. We show that the climate has important direct and indirect effects on all these biotic interactions. We conclude that long time series are essential to identify key biotic interactions in ecosystems, since their importance will be influenced by climatic conditions, and that manipulative treatments are needed in order to obtain the mechanistic understanding needed for robust predictions of future ecosystem changes and their feedback effects.},\n\tlanguage = {en},\n\tnumber = {1624},\n\turldate = {2017-02-07},\n\tjournal = {Phil. Trans. R. Soc. B},\n\tauthor = {Olofsson, Johan and Beest, Mariska te and Ericson, Lars},\n\tmonth = aug,\n\tyear = {2013},\n\tkeywords = {\\#nosource, herbivory, lemmings, moth, plant community composition, reindeer, voles},\n\tpages = {20120486},\n}\n\n\n\n\n\n Predicting impacts of global warming requires understanding of the extent to which plant biomass and production are controlled by bottom-up and top-down drivers. By annually monitoring community composition in grazed control plots and herbivore-free exclosures at an Arctic location for 15 years, we detected multiple biotic interactions. Regular rodent cycles acted as pulses driving synchronous fluctuations in the biomass of field-layer vegetation; reindeer influenced the biomass of taller shrubs, and the abundance of plant pathogenic fungi increased when densities of their host plants increased in exclosures. Two outbreaks of geometrid moths occurred during the study period, with contrasting effects on the field layer: one in 2004 had marginal effects, while one in 2012 severely reduced biomass in the control plots and eliminated biomass that had accumulated over 15 years in the exclosures. The latter was followed by a dramatic decline of the dominant understory dwarf-shrub Empetrum hermaphroditum, driven by an interaction between moth herbivory on top buds and leaves, and increased disease severity of a pathogenic fungus. We show that the climate has important direct and indirect effects on all these biotic interactions. We conclude that long time series are essential to identify key biotic interactions in ecosystems, since their importance will be influenced by climatic conditions, and that manipulative treatments are needed in order to obtain the mechanistic understanding needed for robust predictions of future ecosystem changes and their feedback effects.\n
\n\n\n\n \n\n \n \n \n \n \n \n Ecosystem change and stability over multiple decades in the Swedish subarctic: complex processes and multiple drivers.\n \n \n \n \n\n\n \n Callaghan, T. V.; Jonasson, C.; Thierfelder, T.; Yang, Z.; Hedenås, H.; Johansson, M.; Molau, U.; Bogaert, R. V.; Michelsen, A.; Olofsson, J.; Gwynn-Jones, D.; Bokhorst, S.; Phoenix, G.; Bjerke, J. W.; Tømmervik, H.; Christensen, T. R.; Hanna, E.; Koller, E. K.; and Sloan, V. L.\n\n\n \n\n\n\n Phil. Trans. R. Soc. B, 368(1624): 20120488. August 2013.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{callaghan_ecosystem_2013,\n\ttitle = {Ecosystem change and stability over multiple decades in the {Swedish} subarctic: complex processes and multiple drivers},\n\tvolume = {368},\n\tcopyright = {© 2013 The Author(s) Published by the Royal Society. All rights reserved.},\n\tissn = {0962-8436, 1471-2970},\n\tshorttitle = {Ecosystem change and stability over multiple decades in the {Swedish} subarctic},\n\turl = {http://rstb.royalsocietypublishing.org/content/368/1624/20120488},\n\tdoi = {10.1098/rstb.2012.0488},\n\tabstract = {The subarctic environment of northernmost Sweden has changed over the past century, particularly elements of climate and cryosphere. This paper presents a unique geo-referenced record of environmental and ecosystem observations from the area since 1913. Abiotic changes have been substantial. Vegetation changes include not only increases in growth and range extension but also counterintuitive decreases, and stability: all three possible responses. Changes in species composition within the major plant communities have ranged between almost no changes to almost a 50 per cent increase in the number of species. Changes in plant species abundance also vary with particularly large increases in trees and shrubs (up to 600\\%). There has been an increase in abundance of aspen and large changes in other plant communities responding to wetland area increases resulting from permafrost thaw. Populations of herbivores have responded to varying management practices and climate regimes, particularly changing snow conditions. While it is difficult to generalize and scale-up the site-specific changes in ecosystems, this very site-specificity, combined with projections of change, is of immediate relevance to local stakeholders who need to adapt to new opportunities and to respond to challenges. Furthermore, the relatively small area and its unique datasets are a microcosm of the complexity of Arctic landscapes in transition that remains to be documented.},\n\tlanguage = {en},\n\tnumber = {1624},\n\turldate = {2017-02-07},\n\tjournal = {Phil. Trans. R. Soc. B},\n\tauthor = {Callaghan, Terry V. and Jonasson, Christer and Thierfelder, Tomas and Yang, Zhenlin and Hedenås, Henrik and Johansson, Margareta and Molau, Ulf and Bogaert, Rik Van and Michelsen, Anders and Olofsson, Johan and Gwynn-Jones, Dylan and Bokhorst, Stef and Phoenix, Gareth and Bjerke, Jarle W. and Tømmervik, Hans and Christensen, Torben R. and Hanna, Edward and Koller, Eva K. and Sloan, Victoria L.},\n\tmonth = aug,\n\tyear = {2013},\n\tkeywords = {\\#nosource, climate change impacts, ecosystem stability, subarctic environment},\n\tpages = {20120488},\n}\n\n\n\n\n\n The subarctic environment of northernmost Sweden has changed over the past century, particularly elements of climate and cryosphere. This paper presents a unique geo-referenced record of environmental and ecosystem observations from the area since 1913. Abiotic changes have been substantial. Vegetation changes include not only increases in growth and range extension but also counterintuitive decreases, and stability: all three possible responses. Changes in species composition within the major plant communities have ranged between almost no changes to almost a 50 per cent increase in the number of species. Changes in plant species abundance also vary with particularly large increases in trees and shrubs (up to 600%). There has been an increase in abundance of aspen and large changes in other plant communities responding to wetland area increases resulting from permafrost thaw. Populations of herbivores have responded to varying management practices and climate regimes, particularly changing snow conditions. While it is difficult to generalize and scale-up the site-specific changes in ecosystems, this very site-specificity, combined with projections of change, is of immediate relevance to local stakeholders who need to adapt to new opportunities and to respond to challenges. Furthermore, the relatively small area and its unique datasets are a microcosm of the complexity of Arctic landscapes in transition that remains to be documented.\n
\n\n\n\n \n\n \n \n \n \n \n \n Vascular plant litter input in subarctic peat bogs changes Collembola diets and decomposition patterns.\n \n \n \n \n\n\n \n Krab, E. J.; Berg, M. P.; Aerts, R.; van Logtestijn, R. S. P.; and Cornelissen, J. H. C.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 63: 106–115. August 2013.\n \n\n\n\n
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\n\n\n@article{krab_vascular_2013,\n\ttitle = {Vascular plant litter input in subarctic peat bogs changes {Collembola} diets and decomposition patterns},\n\tvolume = {63},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071713001296},\n\tdoi = {10.1016/j.soilbio.2013.03.032},\n\tabstract = {In high-latitude ecosystems climate change induced plant community shifts toward dominance of shrubs and trees will potentially have large consequences for soil carbon dynamics. Changes in the litter layer due to an altered quantity and quality of litter input, or by its indirect effect on the microclimate, might affect the decomposer community.\nTo be able to predict the effects of increased litter input on decomposers and consequently on soil carbon dynamics, we studied the contribution of Collembola to carbon processing in a high-latitude peat bog system. Moreover, we assessed the effects of changing litter inputs on their abundance, diversity and diet choice, using a 13C tracer approach.\nThe δ13C signatures of Collembola in peat moss (Sphagnum fuscum) showed that species differed in their diet. However, when vascular plant litter (Betula pubescens) entered the Sphagnum peat ecosystem, the δ13C signatures of the Collembola, changed and species-specific differences disappeared. There were no significant changes in Collembola species composition and density after Betula litter addition, but all species showed a strong dietary preference for Betula-associated food sources over Sphagnum; 67\\% of their diet contained carbon originating from Betula litter. Decomposition patterns corresponded to these findings; mass loss (after 406 days of incubation) of Betula increased from 16.1\\% to 26.2\\% when decomposing in combination with Sphagnum, and Sphagnum decomposed even slower in combination with Betula litter (from 4.7\\% to 1.9\\%).\nOur results indicate that the change in litter quality rather than its effects on microclimate is the main way in which vascular litter inputs alter the role of Collembola in carbon turnover. Collembola are plastic in their diet choice, which implies that changes in carbon turnover rates in situations where vegetation shifts occur, might well be due to diet shifts of the present decomposer community rather than by changes in species composition.},\n\turldate = {2017-02-08},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Krab, Eveline J. and Berg, Matty P. and Aerts, Rien and van Logtestijn, Richard S. P. and Cornelissen, Johannes H. C.},\n\tmonth = aug,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Diet, Enrichment, Litter mixing, Soil invertebrates, Springtails, climate change, peat moss, shrubs, stable isotopes, δ13C},\n\tpages = {106--115},\n}\n\n\n\n\n\n In high-latitude ecosystems climate change induced plant community shifts toward dominance of shrubs and trees will potentially have large consequences for soil carbon dynamics. Changes in the litter layer due to an altered quantity and quality of litter input, or by its indirect effect on the microclimate, might affect the decomposer community. To be able to predict the effects of increased litter input on decomposers and consequently on soil carbon dynamics, we studied the contribution of Collembola to carbon processing in a high-latitude peat bog system. Moreover, we assessed the effects of changing litter inputs on their abundance, diversity and diet choice, using a 13C tracer approach. The δ13C signatures of Collembola in peat moss (Sphagnum fuscum) showed that species differed in their diet. However, when vascular plant litter (Betula pubescens) entered the Sphagnum peat ecosystem, the δ13C signatures of the Collembola, changed and species-specific differences disappeared. There were no significant changes in Collembola species composition and density after Betula litter addition, but all species showed a strong dietary preference for Betula-associated food sources over Sphagnum; 67% of their diet contained carbon originating from Betula litter. Decomposition patterns corresponded to these findings; mass loss (after 406 days of incubation) of Betula increased from 16.1% to 26.2% when decomposing in combination with Sphagnum, and Sphagnum decomposed even slower in combination with Betula litter (from 4.7% to 1.9%). Our results indicate that the change in litter quality rather than its effects on microclimate is the main way in which vascular litter inputs alter the role of Collembola in carbon turnover. Collembola are plastic in their diet choice, which implies that changes in carbon turnover rates in situations where vegetation shifts occur, might well be due to diet shifts of the present decomposer community rather than by changes in species composition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Herbivory prevents positive responses of lowland plants to warmer and more fertile conditions at high altitudes.\n \n \n \n \n\n\n \n Kaarlejärvi, E.; Eskelinen, A.; and Olofsson, J.\n\n\n \n\n\n\n Functional Ecology, 27(5): 1244–1253. October 2013.\n \n\n\n\n
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\n\n\n@article{kaarlejarvi_herbivory_2013,\n\ttitle = {Herbivory prevents positive responses of lowland plants to warmer and more fertile conditions at high altitudes},\n\tvolume = {27},\n\tissn = {1365-2435},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12113/abstract},\n\tdoi = {10.1111/1365-2435.12113},\n\tabstract = {* Warm-adapted low elevation plants are expected to exhibit considerable range shifts to higher altitudes and latitudes as a result of climate warming and increased nutrient loads. However, empirical studies show that the magnitude and direction of plant responses are highly species- and site-specific, suggesting that several additional drivers interact with warmer climate.\n\n\n* We experimentally tested the interactive effects of climate warming, mammalian herbivory and soil fertility on low elevation plants. Seedlings of three warm-adapted lowland forbs (Epilobium angustifolium, Silene dioica and Solidago virgaurea) were transplanted to an open tundra site with native mountain tundra vegetation, and the effects of full factorial combinations of herbivore exclosures, warming and fertilization on transplant survival, growth and flowering were studied for two growing seasons. We also investigated the response of native vegetation biomass to the same treatments and compared it with the responses of transplanted lowland forbs.\n\n\n* Effects of both warming and fertilization on the transplanted lowland forbs strongly hinged on herbivore exclusion, resulting in 2–13-fold increase in biomass in warmed and fertilized plots without herbivores compared with warmed and fertilized plots with herbivores present, the magnitude depending on the species. While warm-adapted transplants benefited from warming, the native tundra plant community biomass did not respond to warming treatment.\n\n\n* Our results show that grazing limits the growth of transplants under warmer and more productive conditions, indicating that the expansion of lowland plant species to higher altitudes with warming may be hampered by mammalian herbivory. Furthermore, our results also suggest that migration of warm-adapted species into lightly grazed high-altitude tundra ecosystems might transform these communities to be more responsive to warmer climate and nutrient loads. Studies that do not consider species' upward shifts from lower altitudes might thus have underestimated vegetation responses to global warming, as well as the potential of herbivory to influence these responses.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-08},\n\tjournal = {Functional Ecology},\n\tauthor = {Kaarlejärvi, Elina and Eskelinen, Anu and Olofsson, Johan},\n\tmonth = oct,\n\tyear = {2013},\n\tkeywords = {\\#nosource, consumer control, global warming, grazing, range shift, reindeer, thermophilic plant, tundra, upward migration},\n\tpages = {1244--1253},\n}\n\n\n\n\n\n * Warm-adapted low elevation plants are expected to exhibit considerable range shifts to higher altitudes and latitudes as a result of climate warming and increased nutrient loads. However, empirical studies show that the magnitude and direction of plant responses are highly species- and site-specific, suggesting that several additional drivers interact with warmer climate. * We experimentally tested the interactive effects of climate warming, mammalian herbivory and soil fertility on low elevation plants. Seedlings of three warm-adapted lowland forbs (Epilobium angustifolium, Silene dioica and Solidago virgaurea) were transplanted to an open tundra site with native mountain tundra vegetation, and the effects of full factorial combinations of herbivore exclosures, warming and fertilization on transplant survival, growth and flowering were studied for two growing seasons. We also investigated the response of native vegetation biomass to the same treatments and compared it with the responses of transplanted lowland forbs. * Effects of both warming and fertilization on the transplanted lowland forbs strongly hinged on herbivore exclusion, resulting in 2–13-fold increase in biomass in warmed and fertilized plots without herbivores compared with warmed and fertilized plots with herbivores present, the magnitude depending on the species. While warm-adapted transplants benefited from warming, the native tundra plant community biomass did not respond to warming treatment. * Our results show that grazing limits the growth of transplants under warmer and more productive conditions, indicating that the expansion of lowland plant species to higher altitudes with warming may be hampered by mammalian herbivory. Furthermore, our results also suggest that migration of warm-adapted species into lightly grazed high-altitude tundra ecosystems might transform these communities to be more responsive to warmer climate and nutrient loads. Studies that do not consider species' upward shifts from lower altitudes might thus have underestimated vegetation responses to global warming, as well as the potential of herbivory to influence these responses.\n
\n\n\n\n \n\n \n \n \n \n \n \n Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe.\n \n \n \n \n\n\n \n Lenoir, J.; Graae, B. J.; Aarrestad, P. A.; Alsos, I. G.; Armbruster, W. S.; Austrheim, G.; Bergendorff, C.; Birks, H. J. B.; Bråthen, K. A.; Brunet, J.; Bruun, H. H.; Dahlberg, C. J.; Decocq, G.; Diekmann, M.; Dynesius, M.; Ejrnæs, R.; Grytnes, J.; Hylander, K.; Klanderud, K.; Luoto, M.; Milbau, A.; Moora, M.; Nygaard, B.; Odland, A.; Ravolainen, V. T.; Reinhardt, S.; Sandvik, S. M.; Schei, F. H.; Speed, J. D. M.; Tveraabak, L. U.; Vandvik, V.; Velle, L. G.; Virtanen, R.; Zobel, M.; and Svenning, J.\n\n\n \n\n\n\n Global Change Biology, 19(5): 1470–1481. May 2013.\n \n\n\n\n
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\n\n\n@article{lenoir_local_2013,\n\ttitle = {Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across {Northern} {Europe}},\n\tvolume = {19},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/gcb.12129/abstract},\n\tdoi = {10.1111/gcb.12129},\n\tabstract = {Recent studies from mountainous areas of small spatial extent ({\\textless}2500 km2) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within {\\textless}1000-m2 units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km2 units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km2 units. Ellenberg temperature indicator values in combination with plant assemblages explained 46–72\\% of variation in LmT and 92–96\\% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km2 units peaked at 60–65°N and increased with terrain roughness, averaging 1.97 °C (SD = 0.84 °C) and 2.68 °C (SD = 1.26 °C) within the flattest and roughest units respectively. Complex interactions between topography-related variables and latitude explained 35\\% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km2 units was, on average, 1.8 times greater (0.32 °C km−1) than spatial turnover in growing-season GiT (0.18 °C km−1). We conclude that thermal variability within 1-km2 units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2016-11-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Lenoir, Jonathan and Graae, Bente Jessen and Aarrestad, Per Arild and Alsos, Inger Greve and Armbruster, W. Scott and Austrheim, Gunnar and Bergendorff, Claes and Birks, H. John B. and Bråthen, Kari Anne and Brunet, Jörg and Bruun, Hans Henrik and Dahlberg, Carl Johan and Decocq, Guillaume and Diekmann, Martin and Dynesius, Mats and Ejrnæs, Rasmus and Grytnes, John-Arvid and Hylander, Kristoffer and Klanderud, Kari and Luoto, Miska and Milbau, Ann and Moora, Mari and Nygaard, Bettina and Odland, Arvid and Ravolainen, Virve Tuulia and Reinhardt, Stefanie and Sandvik, Sylvi Marlen and Schei, Fride Høistad and Speed, James David Mervyn and Tveraabak, Liv Unn and Vandvik, Vigdis and Velle, Liv Guri and Virtanen, Risto and Zobel, Martin and Svenning, Jens-Christian},\n\tmonth = may,\n\tyear = {2013},\n\tkeywords = {\\#nosource, Ellenberg indicator value, Spatial heterogeneity, Spatial scale, climate change, climatic heterogeneity, community-inferred temperature, plant community, temperature, topoclimate, topography},\n\tpages = {1470--1481},\n}\n\n\n\n\n\n Recent studies from mountainous areas of small spatial extent (\\textless2500 km2) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within \\textless1000-m2 units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km2 units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km2 units. Ellenberg temperature indicator values in combination with plant assemblages explained 46–72% of variation in LmT and 92–96% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km2 units peaked at 60–65°N and increased with terrain roughness, averaging 1.97 °C (SD = 0.84 °C) and 2.68 °C (SD = 1.26 °C) within the flattest and roughest units respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km2 units was, on average, 1.8 times greater (0.32 °C km−1) than spatial turnover in growing-season GiT (0.18 °C km−1). We conclude that thermal variability within 1-km2 units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.\n
\n\n\n\n \n\n \n \n \n \n \n \n How extreme is an extreme climatic event to a subarctic peatland springtail community?.\n \n \n \n \n\n\n \n Krab, E. J.; Van Schrojenstein Lantman, I. M.; Cornelissen, J. H. C.; and Berg, M. P.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 59: 16–24. April 2013.\n 00010\n\n\n\n
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\n\n\n@article{krab_how_2013,\n\ttitle = {How extreme is an extreme climatic event to a subarctic peatland springtail community?},\n\tvolume = {59},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071712004804},\n\tdoi = {10.1016/j.soilbio.2012.12.012},\n\tabstract = {Extreme climate events are increasing in frequency and duration and may directly impact belowground foodwebs and the activities of component soil organisms. The soil invertebrate community, which includes keystone decomposers, might respond to these newly induced soil microclimate conditions by shifts in density, species composition, spatial patterning and/or functional traits.\nTo test if and how short-term extreme climatic conditions alter the structure, the vertical stratification and the community weighted trait means of the springtail (Collembola) community in sub-arctic peatbogs, we experimentally subjected Sphagnum peat cores in a field setting to factorial treatments of elevated temperature and episodically increased moisture content.\nThe large precipitation peaks did not affect the springtail community, but an average soil temperature increase of 4 °C halved its density in the shallower peat layers, mainly caused by the reduced dominance of Folsomia quadrioculata. A hypothesized net downward shift of the surface-dwelling springtail community, however, was not observed. We observed species-specific responses to warming but the overall community composition in subsequent organic layers was not significantly altered. Although the effects of an extreme warming event on density, species composition and vertical stratification pattern seemed subtle, functional trait analysis revealed directional community responses, i.e. an overall increase of soil-dwelling species due to warming, even though warming did not alter layer-specific community weighted trait means.\nWe suggest that subtle changes in moisture conditions, due to increased evapotranspiration, have decreased typically surface-dwelling species relative to soil-dwelling species. The extent to which this directional change in the community is maintained after an extreme event, and its costs for the community's resilience to multiple sequential extreme events will consequently determine its longer-term effects on the community and on ecosystem functioning.},\n\turldate = {2017-02-08},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Krab, Eveline J. and Van Schrojenstein Lantman, Irene M. and Cornelissen, Johannes H. C. and Berg, Matty P.},\n\tmonth = apr,\n\tyear = {2013},\n\tnote = {00010},\n\tkeywords = {\\#nosource, Blanket bog, Collembola, Extreme weather events, Functional traits, Soil invertebrates, Vertical distribution, Warming, climate change, precipitation, soil microclimate},\n\tpages = {16--24},\n}\n\n\n\n\n\n Extreme climate events are increasing in frequency and duration and may directly impact belowground foodwebs and the activities of component soil organisms. The soil invertebrate community, which includes keystone decomposers, might respond to these newly induced soil microclimate conditions by shifts in density, species composition, spatial patterning and/or functional traits. To test if and how short-term extreme climatic conditions alter the structure, the vertical stratification and the community weighted trait means of the springtail (Collembola) community in sub-arctic peatbogs, we experimentally subjected Sphagnum peat cores in a field setting to factorial treatments of elevated temperature and episodically increased moisture content. The large precipitation peaks did not affect the springtail community, but an average soil temperature increase of 4 °C halved its density in the shallower peat layers, mainly caused by the reduced dominance of Folsomia quadrioculata. A hypothesized net downward shift of the surface-dwelling springtail community, however, was not observed. We observed species-specific responses to warming but the overall community composition in subsequent organic layers was not significantly altered. Although the effects of an extreme warming event on density, species composition and vertical stratification pattern seemed subtle, functional trait analysis revealed directional community responses, i.e. an overall increase of soil-dwelling species due to warming, even though warming did not alter layer-specific community weighted trait means. We suggest that subtle changes in moisture conditions, due to increased evapotranspiration, have decreased typically surface-dwelling species relative to soil-dwelling species. The extent to which this directional change in the community is maintained after an extreme event, and its costs for the community's resilience to multiple sequential extreme events will consequently determine its longer-term effects on the community and on ecosystem functioning.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant community type and small-scale disturbances, but not altitude, influence the invasibility in subarctic ecosystems.\n \n \n \n \n\n\n \n Milbau, A.; Shevtsova, A.; Osler, N.; Mooshammer, M.; and Graae, B. J.\n\n\n \n\n\n\n New Phytologist, 197(3): 1002–1011. February 2013.\n 00027\n\n\n\n
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\n\n\n@article{milbau_plant_2013,\n\ttitle = {Plant community type and small-scale disturbances, but not altitude, influence the invasibility in subarctic ecosystems},\n\tvolume = {197},\n\tissn = {1469-8137},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/nph.12054/abstract},\n\tdoi = {10.1111/nph.12054},\n\tabstract = {* Little of our knowledge about invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect invasibility in a subarctic ecosystem.\n\n\n* Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient.\n\n\n* Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, invasibility did not decrease with increasing elevation, and it was also not related to summer temperature.\n\n\n* Our data suggest that biotic resistance might be more important than abiotic stress for invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {New Phytologist},\n\tauthor = {Milbau, Ann and Shevtsova, Anna and Osler, Nora and Mooshammer, Maria and Graae, Bente J.},\n\tmonth = feb,\n\tyear = {2013},\n\tnote = {00027},\n\tkeywords = {\\#nosource, Empetrum hermaphroditum, arctic and alpine ecosystems, disturbance, elevation, invasibility, invasion, subarctic, tundra},\n\tpages = {1002--1011},\n}\n\n\n\n\n\n * Little of our knowledge about invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect invasibility in a subarctic ecosystem. * Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient. * Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, invasibility did not decrease with increasing elevation, and it was also not related to summer temperature. * Our data suggest that biotic resistance might be more important than abiotic stress for invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dark Carbon Fixation: An Important Process in Lake Sediments.\n \n \n \n \n\n\n \n Santoro, A. L.; Bastviken, D.; Gudasz, C.; Tranvik, L.; and Enrich-Prast, A.\n\n\n \n\n\n\n PLOS ONE, 8(6): e65813. June 2013.\n Publisher: Public Library of Science\n\n\n\n
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\n\n\n@article{santoro_dark_2013,\n\ttitle = {Dark {Carbon} {Fixation}: {An} {Important} {Process} in {Lake} {Sediments}},\n\tvolume = {8},\n\tissn = {1932-6203},\n\tshorttitle = {Dark {Carbon} {Fixation}},\n\turl = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065813},\n\tdoi = {10.1371/journal.pone.0065813},\n\tabstract = {Close to redox boundaries, dark carbon fixation by chemoautotrophic bacteria may be a large contributor to overall carbon fixation. Still, little is known about the relative importance of this process in lake systems, in spite the potentially high chemoautotrophic potential of lake sediments. We compared rates of dark carbon fixation, bacterial production and oxygen consumption in sediments from four Swedish boreal and seven tropical Brazilian lakes. Rates were highly variable and dark carbon fixation amounted up to 80\\% of the total heterotrophic bacterial production. The results indicate that non-photosynthetic carbon fixation can represent a substantial contribution to bacterial biomass production, especially in sediments with low organic matter content.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-08-31},\n\tjournal = {PLOS ONE},\n\tauthor = {Santoro, Ana Lúcia and Bastviken, David and Gudasz, Cristian and Tranvik, Lars and Enrich-Prast, Alex},\n\tmonth = jun,\n\tyear = {2013},\n\tnote = {Publisher: Public Library of Science},\n\tkeywords = {\\#nosource, Carbon dioxide, Carbon fixation, Lakes, Marine bacteria, Sediment, Slurries, Surface water, Water columns},\n\tpages = {e65813},\n}\n\n\n\n\n\n Close to redox boundaries, dark carbon fixation by chemoautotrophic bacteria may be a large contributor to overall carbon fixation. Still, little is known about the relative importance of this process in lake systems, in spite the potentially high chemoautotrophic potential of lake sediments. We compared rates of dark carbon fixation, bacterial production and oxygen consumption in sediments from four Swedish boreal and seven tropical Brazilian lakes. Rates were highly variable and dark carbon fixation amounted up to 80% of the total heterotrophic bacterial production. The results indicate that non-photosynthetic carbon fixation can represent a substantial contribution to bacterial biomass production, especially in sediments with low organic matter content.\n
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\n \n \n\n \n \n \n \n \n \n The response of forest plant regeneration to temperature variation along a latitudinal gradient.\n \n \n \n \n\n\n \n De Frenne, P.; Graae, B. J.; Brunet, J.; Shevtsova, A.; De Schrijver, A.; Chabrerie, O.; Cousins, S. A. O.; Decocq, G.; Diekmann, M.; Hermy, M.; Heinken, T.; Kolb, A.; Nilsson, C.; Stanton, S.; and Verheyen, K.\n\n\n \n\n\n\n Annals of Botany, 109(5): 1037–1046. April 2012.\n \n\n\n\n
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\n\n\n@article{de_frenne_response_2012,\n\ttitle = {The response of forest plant regeneration to temperature variation along a latitudinal gradient},\n\tvolume = {109},\n\tissn = {0305-7364},\n\turl = {https://doi.org/10.1093/aob/mcs015},\n\tdoi = {10.1093/aob/mcs015},\n\tabstract = {The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming.Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (first experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantified by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments.Spring warming increased emergence rates and seedling growth in the early-flowering forb A. nemorosa. Seedlings of the summer-flowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The above-ground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted.Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics.},\n\tnumber = {5},\n\turldate = {2024-03-27},\n\tjournal = {Annals of Botany},\n\tauthor = {De Frenne, Pieter and Graae, Bente J. and Brunet, Jörg and Shevtsova, Anna and De Schrijver, An and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Diekmann, Martin and Hermy, Martin and Heinken, Thilo and Kolb, Annette and Nilsson, Christer and Stanton, Sharon and Verheyen, Kris},\n\tmonth = apr,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Anemone nemorosa, Milium effusum, climate change, common garden, growth chambers, latitudinal gradient, local adaptation, plant regeneration, range edges, recruitment, seedling establishment, temperature},\n\tpages = {1037--1046},\n}\n\n\n\n\n\n The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming.Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (first experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantified by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments.Spring warming increased emergence rates and seedling growth in the early-flowering forb A. nemorosa. Seedlings of the summer-flowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The above-ground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted.Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of dispersal on community structure of aquatic insects in Arctic lakes and streams.\n \n \n \n \n\n\n \n Khan, H.\n\n\n \n\n\n\n Master's thesis, Umeå University, Umeå, Sweden, 2012.\n 00000\n\n\n\n
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\n\n\n@mastersthesis{khan_effects_2012,\n\taddress = {Umeå, Sweden},\n\ttitle = {Effects of dispersal on community structure of aquatic insects in {Arctic} lakes and streams},\n\turl = {http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-62921},\n\tabstract = {Effects of dispersal on community structure of aquatic insects in Arctic lakes and streams},\n\tlanguage = {eng},\n\turldate = {2018-06-08},\n\tschool = {Umeå University},\n\tauthor = {Khan, Habibur},\n\tcollaborator = {Hein, Catherine L.},\n\tyear = {2012},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Effects of dispersal on community structure of aquatic insects in Arctic lakes and streams\n
\n\n\n\n \n\n \n \n \n \n \n \n Strike mechanics of an ambush predator: the spearing mantis shrimp.\n \n \n \n \n\n\n \n deVries , M. S.; Murphy, E. a. K.; and Patek, S. N.\n\n\n \n\n\n\n Journal of Experimental Biology, 215(24): 4374–4384. December 2012.\n \n\n\n\n
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\n\n\n@article{devries_strike_2012,\n\ttitle = {Strike mechanics of an ambush predator: the spearing mantis shrimp},\n\tvolume = {215},\n\tcopyright = {© 2012.},\n\tissn = {0022-0949, 1477-9145},\n\tshorttitle = {Strike mechanics of an ambush predator},\n\turl = {https://jeb.biologists.org/content/215/24/4374},\n\tdoi = {10.1242/jeb.075317},\n\tabstract = {Skip to Next Section\nAmbush predation is characterized by an animal scanning the environment from a concealed position and then rapidly executing a surprise attack. Mantis shrimp (Stomatopoda) consist of both ambush predators (‘spearers’) and foragers (‘smashers’). Spearers hide in sandy burrows and capture evasive prey, whereas smashers search for prey away from their burrows and typically hammer hard-shelled, sedentary prey. Here, we examined the kinematics, morphology and field behavior of spearing mantis shrimp and compared them with previously studied smashers. Using two species with dramatically different adult sizes, we found that strikes produced by the diminutive species, Alachosquilla vicina, were faster (mean peak speed 5.72±0.91 m s–1; mean duration 3.26±0.41 ms) than the strikes produced by the large species, Lysiosquillina maculata (mean peak speed 2.30±0.85 m s–1; mean duration 24.98±9.68 ms). Micro-computed tomography and dissections showed that both species have the spring and latch structures that are used in other species for producing a spring-loaded strike; however, kinematic analyses indicated that only A. vicina consistently engages the elastic mechanism. In the field, L. maculata ambushed evasive prey primarily at night while hidden in burrows, striking with both long and short durations compared with laboratory videos. We expected ambush predators to strike with very high speeds, yet instead we found that these spearing mantis shrimp struck more slowly and with longer durations than smashers. Nonetheless, the strikes of spearers occurred at similar speeds and durations to those of other aquatic predators of evasive prey. Although counterintuitive, these findings suggest that ambush predators do not actually need to produce extremely high speeds, and that the very fastest predators are using speed to achieve other mechanical feats, such as producing large impact forces.},\n\tlanguage = {en},\n\tnumber = {24},\n\turldate = {2019-07-16},\n\tjournal = {Journal of Experimental Biology},\n\tauthor = {deVries, M. S. and Murphy, E. a. K. and Patek, S. N.},\n\tmonth = dec,\n\tyear = {2012},\n\tpmid = {23175528},\n\tkeywords = {\\#nosource},\n\tpages = {4374--4384},\n}\n\n\n\n\n\n Skip to Next Section Ambush predation is characterized by an animal scanning the environment from a concealed position and then rapidly executing a surprise attack. Mantis shrimp (Stomatopoda) consist of both ambush predators (‘spearers’) and foragers (‘smashers’). Spearers hide in sandy burrows and capture evasive prey, whereas smashers search for prey away from their burrows and typically hammer hard-shelled, sedentary prey. Here, we examined the kinematics, morphology and field behavior of spearing mantis shrimp and compared them with previously studied smashers. Using two species with dramatically different adult sizes, we found that strikes produced by the diminutive species, Alachosquilla vicina, were faster (mean peak speed 5.72±0.91 m s–1; mean duration 3.26±0.41 ms) than the strikes produced by the large species, Lysiosquillina maculata (mean peak speed 2.30±0.85 m s–1; mean duration 24.98±9.68 ms). Micro-computed tomography and dissections showed that both species have the spring and latch structures that are used in other species for producing a spring-loaded strike; however, kinematic analyses indicated that only A. vicina consistently engages the elastic mechanism. In the field, L. maculata ambushed evasive prey primarily at night while hidden in burrows, striking with both long and short durations compared with laboratory videos. We expected ambush predators to strike with very high speeds, yet instead we found that these spearing mantis shrimp struck more slowly and with longer durations than smashers. Nonetheless, the strikes of spearers occurred at similar speeds and durations to those of other aquatic predators of evasive prey. Although counterintuitive, these findings suggest that ambush predators do not actually need to produce extremely high speeds, and that the very fastest predators are using speed to achieve other mechanical feats, such as producing large impact forces.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stem Secondary Growth of Tundra Shrubs: Impact of Environmental Factors and Relationships with Apical Growth.\n \n \n \n \n\n\n \n Campioli, M.; Leblans, N.; and Michelsen, A.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 44(1): 16–25. February 2012.\n \n\n\n\n
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\n\n\n@article{campioli_stem_2012,\n\ttitle = {Stem {Secondary} {Growth} of {Tundra} {Shrubs}: {Impact} of {Environmental} {Factors} and {Relationships} with {Apical} {Growth}},\n\tvolume = {44},\n\tissn = {1523-0430},\n\tshorttitle = {Stem {Secondary} {Growth} of {Tundra} {Shrubs}},\n\turl = {https://doi.org/10.1657/1938-4246-44.1.16},\n\tdoi = {10.1657/1938-4246-44.1.16},\n\tabstract = {Our knowledge of stem secondary growth of arctic shrubs (a key component of tundra net primary production, NPP) is very limited. Here, we investigated the impact of the physical elements of the environment on shrub secondary growth by comparing annual growth rates of model species from similar habitats at contrasting altitude, microtopography, latitude, geographical location, and soil type, in both the sub- and High Arctic. We found that secondary growth has a modest sensitivity to the environment but with large differences among species. For example, the evergreen Cassiope tetragona is affected by altitude, microtopography, and latitude, whereas the evergreen Empetrum hermaphroditum has rather constant secondary growth in all environments. Deciduous species seem to be most affected by microtopography. Furthermore, the impact of the environment on secondary growth differed from the impact on primary growth (stem apical growth, stem length, and apical growth of stem plus leaves), in some cases even with opposite responses. Thus caution should be taken when estimating the impact of the environment on shrub growth from apical growth only. Integration of our data set with the (very limited) previously published information on secondary growth provides an overview of its contribution to NPP and annual growth rates for 9 arctic species at 18 sites in Sweden, Greenland, Svalbard, Alaska, and the Alps.},\n\tnumber = {1},\n\turldate = {2019-05-20},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Campioli, Matteo and Leblans, Niki and Michelsen, Anders},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {\\#nosource},\n\tpages = {16--25},\n}\n\n\n\n\n\n Our knowledge of stem secondary growth of arctic shrubs (a key component of tundra net primary production, NPP) is very limited. Here, we investigated the impact of the physical elements of the environment on shrub secondary growth by comparing annual growth rates of model species from similar habitats at contrasting altitude, microtopography, latitude, geographical location, and soil type, in both the sub- and High Arctic. We found that secondary growth has a modest sensitivity to the environment but with large differences among species. For example, the evergreen Cassiope tetragona is affected by altitude, microtopography, and latitude, whereas the evergreen Empetrum hermaphroditum has rather constant secondary growth in all environments. Deciduous species seem to be most affected by microtopography. Furthermore, the impact of the environment on secondary growth differed from the impact on primary growth (stem apical growth, stem length, and apical growth of stem plus leaves), in some cases even with opposite responses. Thus caution should be taken when estimating the impact of the environment on shrub growth from apical growth only. Integration of our data set with the (very limited) previously published information on secondary growth provides an overview of its contribution to NPP and annual growth rates for 9 arctic species at 18 sites in Sweden, Greenland, Svalbard, Alaska, and the Alps.\n
\n\n\n\n \n\n \n \n \n \n \n \n Twenty-Two Years of Warming, Fertilisation and Shading of Subarctic Heath Shrubs Promote Secondary Growth and Plasticity but Not Primary Growth.\n \n \n \n \n\n\n \n Campioli, M.; Leblans, N.; and Michelsen, A.\n\n\n \n\n\n\n PLOS ONE, 7(4): e34842. April 2012.\n \n\n\n\n
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\n\n\n@article{campioli_twenty-two_2012,\n\ttitle = {Twenty-{Two} {Years} of {Warming}, {Fertilisation} and {Shading} of {Subarctic} {Heath} {Shrubs} {Promote} {Secondary} {Growth} and {Plasticity} but {Not} {Primary} {Growth}},\n\tvolume = {7},\n\tissn = {1932-6203},\n\turl = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034842},\n\tdoi = {10.1371/journal.pone.0034842},\n\tabstract = {Most manipulation experiments simulating global change in tundra were short-term or did not measure plant growth directly. Here, we assessed the growth of three shrubs (Cassiope tetragona, Empetrum hermaphroditum and Betula nana) at a subarctic heath in Abisko (Northern Sweden) after 22 years of warming (passive greenhouses), fertilisation (nutrients addition) and shading (hessian fabric), and compare this to observations from the first decade of treatment. We assessed the growth rate of current-year leaves and apical stem (primary growth) and cambial growth (secondary growth), and integrated growth rates with morphological measurements and species coverage. Primary- and total growth of Cassiope and Empetrum were unaffected by manipulations, whereas growth was substantially reduced under fertilisation and shading (but not warming) for Betula. Overall, shrub height and length tended to increase under fertilisation and warming, whereas branching increased mostly in shaded Cassiope. Morphological changes were coupled to increased secondary growth under fertilisation. The species coverage showed a remarkable increase in graminoids in fertilised plots. Shrub response to fertilisation was positive in the short-term but changed over time, likely because of an increased competition with graminoids. More erected postures and large, canopies (requiring enhanced secondary growth for stem reinforcement) likely compensated for the increased light competition in Empetrum and Cassiope but did not avoid growth reduction in the shade intolerant Betula. The impact of warming and shading on shrub growth was more conservative. The lack of growth enhancement under warming suggests the absence of long-term acclimation for processes limiting biomass production. The lack of negative effects of shading on Cassiope was linked to morphological changes increasing the photosynthetic surface. Overall, tundra shrubs showed developmental plasticity over the longer term. However, such plasticity was associated clearly with growth rate trends only in fertilised plots.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2019-05-20},\n\tjournal = {PLOS ONE},\n\tauthor = {Campioli, Matteo and Leblans, Niki and Michelsen, Anders},\n\tmonth = apr,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Analysis of variance, Ecosystems, Fertilization, Fertilizers, Leaves, Plant growth and development, Shrubs, Tundra},\n\tpages = {e34842},\n}\n\n\n\n\n\n Most manipulation experiments simulating global change in tundra were short-term or did not measure plant growth directly. Here, we assessed the growth of three shrubs (Cassiope tetragona, Empetrum hermaphroditum and Betula nana) at a subarctic heath in Abisko (Northern Sweden) after 22 years of warming (passive greenhouses), fertilisation (nutrients addition) and shading (hessian fabric), and compare this to observations from the first decade of treatment. We assessed the growth rate of current-year leaves and apical stem (primary growth) and cambial growth (secondary growth), and integrated growth rates with morphological measurements and species coverage. Primary- and total growth of Cassiope and Empetrum were unaffected by manipulations, whereas growth was substantially reduced under fertilisation and shading (but not warming) for Betula. Overall, shrub height and length tended to increase under fertilisation and warming, whereas branching increased mostly in shaded Cassiope. Morphological changes were coupled to increased secondary growth under fertilisation. The species coverage showed a remarkable increase in graminoids in fertilised plots. Shrub response to fertilisation was positive in the short-term but changed over time, likely because of an increased competition with graminoids. More erected postures and large, canopies (requiring enhanced secondary growth for stem reinforcement) likely compensated for the increased light competition in Empetrum and Cassiope but did not avoid growth reduction in the shade intolerant Betula. The impact of warming and shading on shrub growth was more conservative. The lack of growth enhancement under warming suggests the absence of long-term acclimation for processes limiting biomass production. The lack of negative effects of shading on Cassiope was linked to morphological changes increasing the photosynthetic surface. Overall, tundra shrubs showed developmental plasticity over the longer term. However, such plasticity was associated clearly with growth rate trends only in fertilised plots.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal climate manipulations have only minor effects on litter decomposition rates and N dynamics but strong effects on litter P dynamics of sub-arctic bog species.\n \n \n \n \n\n\n \n Aerts, R.; Callaghan, T. V.; Dorrepaal, E.; van Logtestijn, R. S. P.; and Cornelissen, J. H. C.\n\n\n \n\n\n\n Oecologia, 170(3): 809–819. November 2012.\n 00033\n\n\n\n
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\n\n\n@article{aerts_seasonal_2012,\n\ttitle = {Seasonal climate manipulations have only minor effects on litter decomposition rates and {N} dynamics but strong effects on litter {P} dynamics of sub-arctic bog species},\n\tvolume = {170},\n\tissn = {1432-1939},\n\turl = {https://doi.org/10.1007/s00442-012-2330-z},\n\tdoi = {10.1007/s00442-012-2330-z},\n\tabstract = {Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis {\\textless} Betula {\\textless} Rubus. After 4 years, overall mass loss in the climate-treatment plots was 10 \\% higher compared to the ambient incubation environment. Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-09-17},\n\tjournal = {Oecologia},\n\tauthor = {Aerts, R. and Callaghan, T. V. and Dorrepaal, E. and van Logtestijn, R. S. P. and Cornelissen, J. H. C.},\n\tmonth = nov,\n\tyear = {2012},\n\tnote = {00033},\n\tkeywords = {\\#nosource, Climate warming, Immobilization, Nutrient limitation, Nutrient mineralization, Phosphorus release},\n\tpages = {809--819},\n}\n\n\n\n\n\n Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis \\textless Betula \\textless Rubus. After 4 years, overall mass loss in the climate-treatment plots was 10 % higher compared to the ambient incubation environment. Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.\n
\n\n\n\n \n\n \n \n \n \n \n \n Climatic niche divergence or conservatism? Environmental niches and range limits in ecologically similar damselflies.\n \n \n \n \n\n\n \n Wellenreuther, M.; Larson, K. W.; and Svensson, E. I.\n\n\n \n\n\n\n Ecology, 93(6): 1353–1366. 2012.\n 00044\n\n\n\n
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\n\n\n\n@article{wellenreuther_climatic_2012,\n\ttitle = {Climatic niche divergence or conservatism? {Environmental} niches and range limits in ecologically similar damselflies},\n\tvolume = {93},\n\tissn = {0012-9658},\n\tshorttitle = {Climatic niche divergence or conservatism?},\n\turl = {http://www.esajournals.org.ludwig.lub.lu.se/doi/abs/10.1890/11-1181.1},\n\tdoi = {10.1890/11-1181.1},\n\tnumber = {6},\n\tjournal = {Ecology},\n\tauthor = {Wellenreuther, Maren and Larson, Keith W. and Svensson, Erik I.},\n\tyear = {2012},\n\tnote = {00044},\n\tkeywords = {\\#nosource, Biogeography, Calopteryx splendens;, Calopteryx virgo, climate, ecological speciation, ectotherms, niche divergence, nonecological speciation, sexual selection, thermal adaptation},\n\tpages = {1353--1366},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Phosphorus availability and microbial respiration across different tundra vegetation types.\n \n \n \n \n\n\n \n Giesler, R.; Esberg, C.; Lagerström, A.; and Graae, B. J.\n\n\n \n\n\n\n Biogeochemistry, 108(1-3): 429–445. April 2012.\n 00027\n\n\n\n
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\n\n\n\n@article{giesler_phosphorus_2012,\n\ttitle = {Phosphorus availability and microbial respiration across different tundra vegetation types},\n\tvolume = {108},\n\tissn = {0168-2563, 1573-515X},\n\turl = {http://link.springer.com/10.1007/s10533-011-9609-8},\n\tdoi = {10.1007/s10533-011-9609-8},\n\tlanguage = {en},\n\tnumber = {1-3},\n\turldate = {2015-08-18},\n\tjournal = {Biogeochemistry},\n\tauthor = {Giesler, Reiner and Esberg, Camilla and Lagerström, Anna and Graae, Bente J.},\n\tmonth = apr,\n\tyear = {2012},\n\tnote = {00027},\n\tkeywords = {\\#nosource},\n\tpages = {429--445},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Crossing the threshold: the power of multi-level experiments in identifying global change responses.\n \n \n \n \n\n\n \n Kardol, P.; De Long, J. R.; and Sundqvist, M. K.\n\n\n \n\n\n\n New Phytologist, 196(2): 323–326. October 2012.\n 00015\n\n\n\n
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\n\n\n\n@article{kardol_crossing_2012,\n\ttitle = {Crossing the threshold: the power of multi-level experiments in identifying global change responses},\n\tvolume = {196},\n\tissn = {1469-8137},\n\tshorttitle = {Crossing the threshold},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2012.04341.x/abstract},\n\tdoi = {10.1111/j.1469-8137.2012.04341.x},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-04-28},\n\tjournal = {New Phytologist},\n\tauthor = {Kardol, Paul and De Long, Jonathan R. and Sundqvist, Maja K.},\n\tmonth = oct,\n\tyear = {2012},\n\tnote = {00015},\n\tkeywords = {\\#nosource, aboveground–belowground linkages, climate change, elevated CO2, grasslands, nitrogen (N) deposition, plant community, plant traits},\n\tpages = {323--326},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n Willow warbler Phylloscopus trochilus nesting in a juniper during a peak lemming year.\n \n \n \n\n\n \n Larson, K. W.; and Kundisch, S.\n\n\n \n\n\n\n Ornis Svecica, 22: 141–143. 2012.\n 00002\n\n\n\n
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\n\n\n\n@article{larson_willow_2012,\n\ttitle = {Willow warbler {Phylloscopus} trochilus nesting in a juniper during a peak lemming year},\n\tvolume = {22},\n\tissn = {1102-6812},\n\tdoi = {10.34080/os.v22.22583},\n\tjournal = {Ornis Svecica},\n\tauthor = {Larson, Keith W. and Kundisch, Sieglinde},\n\tyear = {2012},\n\tnote = {00002},\n\tkeywords = {\\#nosource},\n\tpages = {141--143},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Trends in Caspian Tern Nesting and Diet in San Francisco Bay: Conservation Implications for Terns and Salmonids.\n \n \n \n \n\n\n \n Collis, K.; Roby, D. D.; Larson, K. W.; Adrean, L. J.; Nelson, S. K.; Evans, A. F.; Hostetter, N.; Battaglia, D.; Lyons, D. E.; Marcella, T.; and Patterson, A.\n\n\n \n\n\n\n Waterbirds, 35(1): 25–34. 2012.\n 00002\n\n\n\n
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\n\n\n\n@article{collis_trends_2012,\n\ttitle = {Trends in {Caspian} {Tern} {Nesting} and {Diet} in {San} {Francisco} {Bay}: {Conservation} {Implications} for {Terns} and {Salmonids}},\n\tvolume = {35},\n\tissn = {1524-4695},\n\tshorttitle = {Trends in {Caspian} {Tern} {Nesting} and {Diet} in {San} {Francisco} {Bay}},\n\turl = {http://www.bioone.org.ludwig.lub.lu.se/doi/abs/10.1675/063.035.0103},\n\tdoi = {10.1675/063.035.0103},\n\tnumber = {1},\n\tjournal = {Waterbirds},\n\tauthor = {Collis, Ken and Roby, Daniel D. and Larson, Keith W. and Adrean, Lindsay J. and Nelson, S. Kim and Evans, Allen F. and Hostetter, Nathan and Battaglia, Dan and Lyons, Donald E. and Marcella, Tim and Patterson, Allison},\n\tyear = {2012},\n\tnote = {00002},\n\tkeywords = {\\#nosource},\n\tpages = {25--34},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Linking Hydrogen (δ2H) Isotopes in Feathers and Precipitation: Sources of Variance and Consequences for Assignment to Isoscapes.\n \n \n \n \n\n\n \n Hobson, K. A.; Van Wilgenburg, S. L.; Wassenaar, L. I.; and Larson, K. W.\n\n\n \n\n\n\n PLoS ONE, 7(4): e35137. 2012.\n 00089\n\n\n\n
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\n\n\n@article{hobson_linking_2012,\n\ttitle = {Linking {Hydrogen} (δ{2H}) {Isotopes} in {Feathers} and {Precipitation}: {Sources} of {Variance} and {Consequences} for {Assignment} to {Isoscapes}},\n\tvolume = {7},\n\tissn = {1932-6203},\n\tshorttitle = {Linking {Hydrogen} (δ{2H}) {Isotopes} in {Feathers} and {Precipitation}},\n\turl = {http://dx.doi.org/10.1371/journal.pone.0035137},\n\tdoi = {10.1371/journal.pone.0035137},\n\tabstract = {Tracking small migrant organisms worldwide has been hampered by technological and recovery limitations and sampling bias inherent in exogenous markers. Naturally occurring stable isotopes of H (δ2H) in feathers provide an alternative intrinsic marker of animal origin due to the predictable spatial linkage to underlying hydrologically driven flow of H isotopes into foodwebs. This approach can assess the likelihood that a migrant animal originated from a given location(s) within a continent but requires a robust algorithm linking H isotopes in tissues of interest to an appropriate hydrological isotopic spatio-temporal pattern, such as weighted-annual rainfall. However, a number of factors contribute to or alter expected isotopic patterns in animals. We present results of an extensive investigation into taxonomic and environmental factors influencing feather δ2H patterns across North America.\n\nStable isotope data were measured from 544 feathers from 40 species and 140 known locations. For δ2H, the most parsimonious model explaining 83\\% of the isotopic variance was found with amount-weighted growing-season precipitation δ2H, foraging substrate and migratory strategy.\n\nThis extensive H isotopic analysis of known-origin feathers of songbirds in North America and elsewhere reconfirmed the strong coupling between tissue δ2H and global hydrologic δ2H patterns, and accounting for variance associated with foraging substrate and migratory strategy, can be used in conservation and research for the purpose of assigning birds and other species to their approximate origin.},\n\tnumber = {4},\n\turldate = {2012-04-13},\n\tjournal = {PLoS ONE},\n\tauthor = {Hobson, Keith A. and Van Wilgenburg, Steven L. and Wassenaar, Leonard I. and Larson, Keith W.},\n\tyear = {2012},\n\tnote = {00089},\n\tkeywords = {\\#nosource},\n\tpages = {e35137},\n}\n\n\n\n\n\n Tracking small migrant organisms worldwide has been hampered by technological and recovery limitations and sampling bias inherent in exogenous markers. Naturally occurring stable isotopes of H (δ2H) in feathers provide an alternative intrinsic marker of animal origin due to the predictable spatial linkage to underlying hydrologically driven flow of H isotopes into foodwebs. This approach can assess the likelihood that a migrant animal originated from a given location(s) within a continent but requires a robust algorithm linking H isotopes in tissues of interest to an appropriate hydrological isotopic spatio-temporal pattern, such as weighted-annual rainfall. However, a number of factors contribute to or alter expected isotopic patterns in animals. We present results of an extensive investigation into taxonomic and environmental factors influencing feather δ2H patterns across North America. Stable isotope data were measured from 544 feathers from 40 species and 140 known locations. For δ2H, the most parsimonious model explaining 83% of the isotopic variance was found with amount-weighted growing-season precipitation δ2H, foraging substrate and migratory strategy. This extensive H isotopic analysis of known-origin feathers of songbirds in North America and elsewhere reconfirmed the strong coupling between tissue δ2H and global hydrologic δ2H patterns, and accounting for variance associated with foraging substrate and migratory strategy, can be used in conservation and research for the purpose of assigning birds and other species to their approximate origin.\n
\n\n\n\n \n\n \n \n \n \n \n \n 2.8 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia.\n \n \n \n \n\n\n \n Melles, M.; Brigham-Grette, J.; Minyuk, P. S.; Nowaczyk, N. R.; Wennrich, V.; DeConto, R. M.; Anderson, P. M.; Andreev, A. A.; Coletti, A.; Cook, T. L.; Haltia-Hovi, E.; Kukkonen, M.; Lozhkin, A. V.; Rosén, P.; Tarasov, P.; Vogel, H.; and Wagner, B.\n\n\n \n\n\n\n Science, 337(6092): 315–320. July 2012.\n 00000 \n\n\n\n
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\n\n\n@article{melles_28_2012,\n\ttitle = {2.8 {Million} {Years} of {Arctic} {Climate} {Change} from {Lake} {El}’gygytgyn, {NE} {Russia}},\n\tvolume = {337},\n\tcopyright = {Copyright © 2012, American Association for the Advancement of Science},\n\tissn = {0036-8075, 1095-9203},\n\turl = {http://science.sciencemag.org/content/337/6092/315},\n\tdoi = {10.1126/science.1222135},\n\tabstract = {The reliability of Arctic climate predictions is currently hampered by insufficient knowledge of natural climate variability in the past. A sediment core from Lake El’gygytgyn in northeastern (NE) Russia provides a continuous, high-resolution record from the Arctic, spanning the past 2.8 million years. This core reveals numerous “super interglacials” during the Quaternary; for marine benthic isotope stages (MIS) 11c and 31, maximum summer temperatures and annual precipitation values are {\\textasciitilde}4° to 5°C and {\\textasciitilde}300 millimeters higher than those of MIS 1 and 5e. Climate simulations show that these extreme warm conditions are difficult to explain with greenhouse gas and astronomical forcing alone, implying the importance of amplifying feedbacks and far field influences. The timing of Arctic warming relative to West Antarctic Ice Sheet retreats implies strong interhemispheric climate connectivity.\nA sediment core from a Russian lake provides a high-latitude climate record where prior terrestrial records have been sparse.\nA sediment core from a Russian lake provides a high-latitude climate record where prior terrestrial records have been sparse.},\n\tlanguage = {en},\n\tnumber = {6092},\n\turldate = {2017-09-11},\n\tjournal = {Science},\n\tauthor = {Melles, Martin and Brigham-Grette, Julie and Minyuk, Pavel S. and Nowaczyk, Norbert R. and Wennrich, Volker and DeConto, Robert M. and Anderson, Patricia M. and Andreev, Andrei A. and Coletti, Anthony and Cook, Timothy L. and Haltia-Hovi, Eeva and Kukkonen, Maaret and Lozhkin, Anatoli V. and Rosén, Peter and Tarasov, Pavel and Vogel, Hendrik and Wagner, Bernd},\n\tmonth = jul,\n\tyear = {2012},\n\tpmid = {22722254},\n\tnote = {00000 },\n\tkeywords = {\\#nosource},\n\tpages = {315--320},\n}\n\n\n\n\n\n The reliability of Arctic climate predictions is currently hampered by insufficient knowledge of natural climate variability in the past. A sediment core from Lake El’gygytgyn in northeastern (NE) Russia provides a continuous, high-resolution record from the Arctic, spanning the past 2.8 million years. This core reveals numerous “super interglacials” during the Quaternary; for marine benthic isotope stages (MIS) 11c and 31, maximum summer temperatures and annual precipitation values are ~4° to 5°C and ~300 millimeters higher than those of MIS 1 and 5e. Climate simulations show that these extreme warm conditions are difficult to explain with greenhouse gas and astronomical forcing alone, implying the importance of amplifying feedbacks and far field influences. The timing of Arctic warming relative to West Antarctic Ice Sheet retreats implies strong interhemispheric climate connectivity. A sediment core from a Russian lake provides a high-latitude climate record where prior terrestrial records have been sparse. A sediment core from a Russian lake provides a high-latitude climate record where prior terrestrial records have been sparse.\n
\n\n\n\n \n\n \n \n \n \n \n \n A frozen feast: thawing permafrost increases plant-available nitrogen in subarctic peatlands.\n \n \n \n \n\n\n \n Keuper, F.; van Bodegom, P. M.; Dorrepaal, E.; Weedon, J. T.; van Hal, J.; van Logtestijn, R. S. P.; and Aerts, R.\n\n\n \n\n\n\n Global Change Biology, 18(6): 1998–2007. June 2012.\n 00063\n\n\n\n
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\n\n\n@article{keuper_frozen_2012,\n\ttitle = {A frozen feast: thawing permafrost increases plant-available nitrogen in subarctic peatlands},\n\tvolume = {18},\n\tissn = {1365-2486},\n\tshorttitle = {A frozen feast},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02663.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2012.02663.x},\n\tabstract = {Many of the world's northern peatlands are underlain by rapidly thawing permafrost. Because plant production in these peatlands is often nitrogen (N)-limited, a release of N stored in permafrost may stimulate net primary production or change species composition if it is plant-available. In this study, we aimed to quantify plant-available N in thawing permafrost soils of subarctic peatlands. We compared plant-available N-pools and -fluxes in near-surface permafrost (0–10 cm below the thawfront) to those taken from a current rooting zone layer (5–15 cm depth) across five representative peatlands in subarctic Sweden. A range of complementary methods was used: extractions of inorganic and organic N, inorganic and organic N-release measurements at 0.5 and 11 °C (over 120 days, relevant to different thaw-development scenarios) and a bioassay with Poa alpina test plants. All extraction methods, across all peatlands, consistently showed up to seven times more plant-available N in near-surface permafrost soil compared to the current rooting zone layer. These results were supported by the bioassay experiment, with an eightfold larger plant N-uptake from permafrost soil than from other N-sources such as current rooting zone soil or fresh litter substrates. Moreover, net mineralization rates were much higher in permafrost soils compared to soils from the current rooting zone layer (273 mg N m−2 and 1348 mg N m−2 per growing season for near-surface permafrost at 0.5 °C and 11 °C respectively, compared to −30 mg N m−2 for current rooting zone soil at 11 °C). Hence, our results demonstrate that near-surface permafrost soil of subarctic peatlands can release a biologically relevant amount of plant available nitrogen, both directly upon thawing as well as over the course of a growing season through continued microbial mineralization of organically bound N. Given the nitrogen-limited nature of northern peatlands, this release may have impacts on both plant productivity and species composition.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Keuper, Frida and van Bodegom, Peter M. and Dorrepaal, Ellen and Weedon, James T. and van Hal, Jurgen and van Logtestijn, Richard S. P. and Aerts, Rien},\n\tmonth = jun,\n\tyear = {2012},\n\tnote = {00063},\n\tkeywords = {\\#nosource, Permafrost degradation, Poa alpina, bioassay, climate change, nitrogen cycling, nutrients, palsa mire, subarctic},\n\tpages = {1998--2007},\n}\n\n\n\n\n\n Many of the world's northern peatlands are underlain by rapidly thawing permafrost. Because plant production in these peatlands is often nitrogen (N)-limited, a release of N stored in permafrost may stimulate net primary production or change species composition if it is plant-available. In this study, we aimed to quantify plant-available N in thawing permafrost soils of subarctic peatlands. We compared plant-available N-pools and -fluxes in near-surface permafrost (0–10 cm below the thawfront) to those taken from a current rooting zone layer (5–15 cm depth) across five representative peatlands in subarctic Sweden. A range of complementary methods was used: extractions of inorganic and organic N, inorganic and organic N-release measurements at 0.5 and 11 °C (over 120 days, relevant to different thaw-development scenarios) and a bioassay with Poa alpina test plants. All extraction methods, across all peatlands, consistently showed up to seven times more plant-available N in near-surface permafrost soil compared to the current rooting zone layer. These results were supported by the bioassay experiment, with an eightfold larger plant N-uptake from permafrost soil than from other N-sources such as current rooting zone soil or fresh litter substrates. Moreover, net mineralization rates were much higher in permafrost soils compared to soils from the current rooting zone layer (273 mg N m−2 and 1348 mg N m−2 per growing season for near-surface permafrost at 0.5 °C and 11 °C respectively, compared to −30 mg N m−2 for current rooting zone soil at 11 °C). Hence, our results demonstrate that near-surface permafrost soil of subarctic peatlands can release a biologically relevant amount of plant available nitrogen, both directly upon thawing as well as over the course of a growing season through continued microbial mineralization of organically bound N. Given the nitrogen-limited nature of northern peatlands, this release may have impacts on both plant productivity and species composition.\n
\n\n\n\n \n\n \n \n \n \n \n Moss-specific changes in nitrogen fixation following two decades of warming, shading, and fertilizer addition.\n \n \n \n\n\n \n Sorensen, P. L.; Lett, S.; and Michelsen, A.\n\n\n \n\n\n\n Plant Ecology, 213(4): 695–706. April 2012.\n 00024\n\n\n\n
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\n\n\n@article{sorensen_moss-specific_2012,\n\ttitle = {Moss-specific changes in nitrogen fixation following two decades of warming, shading, and fertilizer addition},\n\tvolume = {213},\n\tissn = {1385-0237},\n\tdoi = {10.1007/s11258-012-0034-4},\n\tabstract = {Climate warming will induce changes in Arctic ecosystem carbon balance, but besides climate, nitrogen availability is a critical controlling factor of carbon cycling. It is therefore essential to obtain knowledge on the influence of a changing climate on nitrogen fixation, as this process is the main source of new nitrogen to arctic ecosystems. In order to gain information on future nitrogen fixation rates in a changing climate, we studied the effects of two decades of warming with passive greenhouses, shading with sackcloth, and fertilization with NPK fertilizer on nitrogen fixation rates. To expand the knowledge on species-specific responses, we measured nitrogen fixation associated with two moss species: Hylocomium splendens and Aulacomnium turgidum. Our expectations of decreased nitrogen fixation rates in the fertilizer and shading treatments were met. However, contrary to our expectation of increased nitrogen fixation in the warming treatment, we observed either no change (Hylocomium) or a decrease (Aulacomnium) in fixation in the warmed plots. We hypothesize that this could be due to moss-specific responses or to long-term induced effects of the warming. For example, we observed that the soil temperature increase induced by the warming treatment was low and insignificant as vegetation height and total vascular plant cover of the warmed plots increased, and moss cover decreased. Hence, truly long-term studies lasting more than two decades provide insights on changes in key biogeochemical processes, which differ from more transient responses to warming in the Arctic.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Plant Ecology},\n\tauthor = {Sorensen, Pernille L. and Lett, Signe and Michelsen, Anders},\n\tmonth = apr,\n\tyear = {2012},\n\tnote = {00024},\n\tkeywords = {\\#nosource, Arctic, Aulacomnium turgidum, Bryophyte, Hylocomium splendens, Nitrogen fixation, Plants, Vegetation cover, Warming, boreal forests, climate change, dwarf shrubs, ecosystem, environmental perturbations, growth-responses, microbial communities, nutrient, simulating climatic-change, sub-arctic heath},\n\tpages = {695--706},\n}\n\n\n\n\n\n Climate warming will induce changes in Arctic ecosystem carbon balance, but besides climate, nitrogen availability is a critical controlling factor of carbon cycling. It is therefore essential to obtain knowledge on the influence of a changing climate on nitrogen fixation, as this process is the main source of new nitrogen to arctic ecosystems. In order to gain information on future nitrogen fixation rates in a changing climate, we studied the effects of two decades of warming with passive greenhouses, shading with sackcloth, and fertilization with NPK fertilizer on nitrogen fixation rates. To expand the knowledge on species-specific responses, we measured nitrogen fixation associated with two moss species: Hylocomium splendens and Aulacomnium turgidum. Our expectations of decreased nitrogen fixation rates in the fertilizer and shading treatments were met. However, contrary to our expectation of increased nitrogen fixation in the warming treatment, we observed either no change (Hylocomium) or a decrease (Aulacomnium) in fixation in the warmed plots. We hypothesize that this could be due to moss-specific responses or to long-term induced effects of the warming. For example, we observed that the soil temperature increase induced by the warming treatment was low and insignificant as vegetation height and total vascular plant cover of the warmed plots increased, and moss cover decreased. Hence, truly long-term studies lasting more than two decades provide insights on changes in key biogeochemical processes, which differ from more transient responses to warming in the Arctic.\n
\n\n\n\n \n\n \n \n \n \n \n Spatiotemporal distribution of threatened high-latitude snowbed and snow patch habitats in warming climate.\n \n \n \n\n\n \n Kivinen, S.; Kaarlejarvi, E.; Jylha, K.; and Raisanen, J.\n\n\n \n\n\n\n Environmental Research Letters, 7(3): 034024. September 2012.\n 00015\n\n\n\n
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\n\n\n@article{kivinen_spatiotemporal_2012,\n\ttitle = {Spatiotemporal distribution of threatened high-latitude snowbed and snow patch habitats in warming climate},\n\tvolume = {7},\n\tissn = {1748-9326},\n\tdoi = {10.1088/1748-9326/7/3/034024},\n\tabstract = {We studied the interannual variation of late summer snow covered area (SCA), i.e. snowbeds and permanent snow patches, in northern Finland and analyzed the role of topographical factors and climatic conditions on the recent and future occurrence of summer snow. SCA for the years 2000, 2004, 2006 and 2009 was derived from Landsat images using a normalized difference snow index (NDSI). Late summer SCA varied notably between the years (1.5-23.0 km(2)). A major part of the late summer snow was located above 900-1000 m and on northern and eastern slopes. A generalized additive model (GAM) showed that the number of years with snow present in 1 km grid squares was strongly positively related to altitude and terrain ruggedness. Parallel examination of interannual variation of SCA and climatic conditions showed that snow cover declines were linked to relatively low snowfall-to-rainfall ratios. Annual mean air temperatures, particularly spring and early winter temperatures, showed increasing trends during the study period. Projected increases in air temperatures and rainfall suggest earlier and more efficient snow melt in the future. This may threaten the occurrence of species and communities related to snowbeds and decrease the beta-diversity of the landscape, and could also affect ecosystem services of the region.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Kivinen, Sonja and Kaarlejarvi, Elina and Jylha, Kirsti and Raisanen, Jouni},\n\tmonth = sep,\n\tyear = {2012},\n\tnote = {00015},\n\tkeywords = {\\#nosource, Biodiversity, alpine vegetation, climate warming, community, cover, ecotone, environment, high-latitude regions, model projections, productivity, remote sensing, snow, snowpatches, temperature, threatened habitats},\n\tpages = {034024},\n}\n\n\n\n\n\n We studied the interannual variation of late summer snow covered area (SCA), i.e. snowbeds and permanent snow patches, in northern Finland and analyzed the role of topographical factors and climatic conditions on the recent and future occurrence of summer snow. SCA for the years 2000, 2004, 2006 and 2009 was derived from Landsat images using a normalized difference snow index (NDSI). Late summer SCA varied notably between the years (1.5-23.0 km(2)). A major part of the late summer snow was located above 900-1000 m and on northern and eastern slopes. A generalized additive model (GAM) showed that the number of years with snow present in 1 km grid squares was strongly positively related to altitude and terrain ruggedness. Parallel examination of interannual variation of SCA and climatic conditions showed that snow cover declines were linked to relatively low snowfall-to-rainfall ratios. Annual mean air temperatures, particularly spring and early winter temperatures, showed increasing trends during the study period. Projected increases in air temperatures and rainfall suggest earlier and more efficient snow melt in the future. This may threaten the occurrence of species and communities related to snowbeds and decrease the beta-diversity of the landscape, and could also affect ecosystem services of the region.\n
\n\n\n\n \n\n \n \n \n \n \n Enzymatic Hydrolysis of Organic Phosphates Adsorbed on Mineral Surfaces.\n \n \n \n\n\n \n Olsson, R.; Giesler, R.; Loring, J. S.; and Persson, P.\n\n\n \n\n\n\n Environmental Science & Technology, 46(1): 285–291. January 2012.\n 00013\n\n\n\n
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\n\n\n@article{olsson_enzymatic_2012,\n\ttitle = {Enzymatic {Hydrolysis} of {Organic} {Phosphates} {Adsorbed} on {Mineral} {Surfaces}},\n\tvolume = {46},\n\tissn = {0013-936X},\n\tdoi = {10.1021/es2028422},\n\tabstract = {Esters of phosphoric acid constitute a sizable fraction of the total phosphorus supply in the environment and thus play an important role in the global phosphorus cycle. Enzymatic hydrolysis of these esters to produce orthophosphate is often a required reaction preceding phosphorus uptake by plants and microorganisms. Generally, adsorption to environmental particles is assumed to limit this process. Here we show, however, that the rate of enzymatic hydrolysis of glucose-1-phosphate (G1P) adsorbed on goethite by acid phosphatase (AcPase) can be of the same order of magnitude as in aqueous solution. The surface process releases carbon to the solution whereas orthophosphate remains adsorbed on goethite. This hydrolysis reaction is strictly an interfacial process governed by the properties of the interface. A high surface concentration of substrate mediates the formation of a catalytically active layer of AcPase, and although adsorption likely reduces the catalytic efficiency of the enzyme, this reduction is almost balanced by the fact that enzyme and substrate are concentrated at the mineral surfaces. Our results suggest that mineral surfaces with appropriate surface properties can be very effective in concentrating substrates and enzymes thereby creating microchemical environments of high enzymatic activity. Hence, also strongly adsorbed molecules in soils and aquatic environments may be subjected to biodegradation by extracellular enzymes.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Olsson, Rickard and Giesler, Reiner and Loring, John S. and Persson, Per},\n\tmonth = jan,\n\tyear = {2012},\n\tnote = {00013},\n\tkeywords = {\\#nosource, Adsorption, Goethite, acid-phosphatase, acquisition, glucose-1-phosphate, interface, manganese-dioxide, montmorillonite, phosphorus, spectroscopy},\n\tpages = {285--291},\n}\n\n\n\n\n\n Esters of phosphoric acid constitute a sizable fraction of the total phosphorus supply in the environment and thus play an important role in the global phosphorus cycle. Enzymatic hydrolysis of these esters to produce orthophosphate is often a required reaction preceding phosphorus uptake by plants and microorganisms. Generally, adsorption to environmental particles is assumed to limit this process. Here we show, however, that the rate of enzymatic hydrolysis of glucose-1-phosphate (G1P) adsorbed on goethite by acid phosphatase (AcPase) can be of the same order of magnitude as in aqueous solution. The surface process releases carbon to the solution whereas orthophosphate remains adsorbed on goethite. This hydrolysis reaction is strictly an interfacial process governed by the properties of the interface. A high surface concentration of substrate mediates the formation of a catalytically active layer of AcPase, and although adsorption likely reduces the catalytic efficiency of the enzyme, this reduction is almost balanced by the fact that enzyme and substrate are concentrated at the mineral surfaces. Our results suggest that mineral surfaces with appropriate surface properties can be very effective in concentrating substrates and enzymes thereby creating microchemical environments of high enzymatic activity. Hence, also strongly adsorbed molecules in soils and aquatic environments may be subjected to biodegradation by extracellular enzymes.\n
\n\n\n\n \n\n \n \n \n \n \n High-Resolution Characterization of Organic Phosphorus in Soil Extracts Using 2D H-1-P-31 NMR Correlation Spectroscopy.\n \n \n \n\n\n \n Vestergren, J.; Vincent, A. G.; Jansson, M.; Persson, P.; Istedt, U.; Groebner, G.; Giesler, R.; and Schleucher, J.\n\n\n \n\n\n\n Environmental Science & Technology, 46(7): 3950–3956. April 2012.\n 00000\n\n\n\n
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\n\n\n@article{vestergren_high-resolution_2012,\n\ttitle = {High-{Resolution} {Characterization} of {Organic} {Phosphorus} in {Soil} {Extracts} {Using} {2D} {H}-1-{P}-31 {NMR} {Correlation} {Spectroscopy}},\n\tvolume = {46},\n\tissn = {0013-936X},\n\tdoi = {10.1021/es204016h},\n\tabstract = {Organic phosphorus (P) compounds represent a major component of soil P in many soils and are key sources of P for microbes and plants. Solution NMR (nuclear magnetic resonance spectroscopy) is a powerful technique for characterizing organic P species. However, P-31 NMR spectra are often complicated by overlapping peaks, which hampers identification and quantification of the numerous P species present in soils. Overlap is often exacerbated by the presence of paramagnetic metal ions, even if they are in complexes with EDTA following NaOH/EDTA extraction. By removing paramagnetic impurities using a new precipitation protocol, we achieved a dramatic improvement in spectral resolution. Furthermore, the obtained reduction in line widths enabled the use of multidimensional NMR methods to resolve overlapping P-31 signals. Using the new protocol on samples from two boreal humus soils with different Fe contents, 2D H-1-P-31 correlation spectra allowed unambiguous identification of a large number of P species based on their P-31 and H-1 chemical shifts and their characteristic coupling patterns, which would not have been possible using previous protocols. This approach can be used to identify organic P species in samples from both terrestrial and aquatic environments increasing our understanding of organic P biogeochemistry.},\n\tlanguage = {English},\n\tnumber = {7},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Vestergren, Johan and Vincent, Andrea G. and Jansson, Mats and Persson, Per and Istedt, Ulrik and Groebner, Gerhard and Giesler, Reiner and Schleucher, Juergen},\n\tmonth = apr,\n\tyear = {2012},\n\tnote = {00000},\n\tkeywords = {\\#nosource, edta, identification, nuclear-magnetic-resonance, phosphates, samples},\n\tpages = {3950--3956},\n}\n\n\n\n\n\n Organic phosphorus (P) compounds represent a major component of soil P in many soils and are key sources of P for microbes and plants. Solution NMR (nuclear magnetic resonance spectroscopy) is a powerful technique for characterizing organic P species. However, P-31 NMR spectra are often complicated by overlapping peaks, which hampers identification and quantification of the numerous P species present in soils. Overlap is often exacerbated by the presence of paramagnetic metal ions, even if they are in complexes with EDTA following NaOH/EDTA extraction. By removing paramagnetic impurities using a new precipitation protocol, we achieved a dramatic improvement in spectral resolution. Furthermore, the obtained reduction in line widths enabled the use of multidimensional NMR methods to resolve overlapping P-31 signals. Using the new protocol on samples from two boreal humus soils with different Fe contents, 2D H-1-P-31 correlation spectra allowed unambiguous identification of a large number of P species based on their P-31 and H-1 chemical shifts and their characteristic coupling patterns, which would not have been possible using previous protocols. This approach can be used to identify organic P species in samples from both terrestrial and aquatic environments increasing our understanding of organic P biogeochemistry.\n
\n\n\n\n \n\n \n \n \n \n \n \n Tundra in the Rain: Differential Vegetation Responses to Three Years of Experimentally Doubled Summer Precipitation in Siberian Shrub and Swedish Bog Tundra.\n \n \n \n \n\n\n \n Keuper, F.; Parmentier, F. W.; Blok, D.; Bodegom, P. M. v.; Dorrepaal, E.; Hal, J. R. v.; Logtestijn, R. S. P. v.; and Aerts, R.\n\n\n \n\n\n\n AMBIO, 41(3): 269–280. July 2012.\n 00015\n\n\n\n
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\n\n\n@article{keuper_tundra_2012,\n\ttitle = {Tundra in the {Rain}: {Differential} {Vegetation} {Responses} to {Three} {Years} of {Experimentally} {Doubled} {Summer} {Precipitation} in {Siberian} {Shrub} and {Swedish} {Bog} {Tundra}},\n\tvolume = {41},\n\tissn = {0044-7447, 1654-7209},\n\tshorttitle = {Tundra in the {Rain}},\n\turl = {http://link.springer.com/article/10.1007/s13280-012-0305-2},\n\tdoi = {10.1007/s13280-012-0305-2},\n\tabstract = {Precipitation amounts and patterns at high latitude sites have been predicted to change as a result of global climatic changes. We addressed vegetation responses to three years of experimentally increased summer precipitation in two previously unaddressed tundra types: Betula nana-dominated shrub tundra (northeast Siberia) and a dry Sphagnum fuscum-dominated bog (northern Sweden). Positive responses to approximately doubled ambient precipitation (an increase of 200 mm year−1) were observed at the Siberian site, for B. nana (30 \\% larger length increments), Salix pulchra (leaf size and length increments) and Arctagrostis latifolia (leaf size and specific leaf area), but none were observed at the Swedish site. Total biomass production did not increase at either of the study sites. This study corroborates studies in other tundra vegetation types and shows that despite regional differences at the plant level, total tundra plant productivity is, at least at the short or medium term, largely irresponsive to experimentally increased summer precipitation.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {AMBIO},\n\tauthor = {Keuper, Frida and Parmentier, Frans-Jan W. and Blok, Daan and Bodegom, Peter M. van and Dorrepaal, Ellen and Hal, Jurgen R. van and Logtestijn, Richard S. P. van and Aerts, Rien},\n\tmonth = jul,\n\tyear = {2012},\n\tnote = {00015},\n\tkeywords = {\\#nosource, Environment, general, Environmental Engineering/Biotechnology, Environmental Management, Irrigation, Meteorology/Climatology, Physical Geography, Water addition, ecology, high latitude, plant traits, primary production, subarctic},\n\tpages = {269--280},\n}\n\n\n\n\n\n Precipitation amounts and patterns at high latitude sites have been predicted to change as a result of global climatic changes. We addressed vegetation responses to three years of experimentally increased summer precipitation in two previously unaddressed tundra types: Betula nana-dominated shrub tundra (northeast Siberia) and a dry Sphagnum fuscum-dominated bog (northern Sweden). Positive responses to approximately doubled ambient precipitation (an increase of 200 mm year−1) were observed at the Siberian site, for B. nana (30 % larger length increments), Salix pulchra (leaf size and length increments) and Arctagrostis latifolia (leaf size and specific leaf area), but none were observed at the Swedish site. Total biomass production did not increase at either of the study sites. This study corroborates studies in other tundra vegetation types and shows that despite regional differences at the plant level, total tundra plant productivity is, at least at the short or medium term, largely irresponsive to experimentally increased summer precipitation.\n
\n\n\n\n \n\n \n \n \n \n \n Terrestrial subsidies to lake food webs: an experimental approach.\n \n \n \n\n\n \n Bartels, P.; Cucherousset, J.; Gudasz, C.; Jansson, M.; Karlsson, J.; Persson, L.; Premke, K.; Rubach, A.; Steger, K.; Tranvik, L. J.; and Eklov, P.\n\n\n \n\n\n\n Oecologia, 168(3): 807–818. March 2012.\n \n\n\n\n
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\n\n\n@article{bartels_terrestrial_2012,\n\ttitle = {Terrestrial subsidies to lake food webs: an experimental approach},\n\tvolume = {168},\n\tissn = {0029-8549},\n\tshorttitle = {Terrestrial subsidies to lake food webs},\n\tdoi = {10.1007/s00442-011-2141-7},\n\tabstract = {Cross-ecosystem movements of material and energy are ubiquitous. Aquatic ecosystems typically receive material that also includes organic matter from the surrounding catchment. Terrestrial-derived (allochthonous) organic matter can enter aquatic ecosystems in dissolved or particulate form. Several studies have highlighted the importance of dissolved organic carbon to aquatic consumers, but less is known about allochthonous particulate organic carbon (POC). Similarly, most studies showing the effects of allochthonous organic carbon (OC) on aquatic consumers have investigated pelagic habitats; the effects of allochthonous OC on benthic communities are less well studied. Allochthonous inputs might further decrease primary production through light reduction, thereby potentially affecting autotrophic resource availability to consumers. Here, an enclosure experiment was carried out to test the importance of POC input and light availability on the resource use in a benthic food web of a clear-water lake. Corn starch (a C-4 plant) was used as a POC source due to its insoluble nature and its distinct carbon stable isotope value (delta C-13). The starch carbon was closely dispersed over the bottom of the enclosures to study the fate of a POC source exclusively available to sediment biota. The addition of starch carbon resulted in a clear shift in the isotopic signature of surface-dwelling herbivorous and predatory invertebrates. Although the starch carbon was added solely to the sediment surface, the carbon originating from the starch reached zooplankton. We suggest that allochthonous POC can subsidize benthic food webs directly and can be further transferred to pelagic systems, thereby highlighting the importance of benthic pathways for pelagic habitats.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Oecologia},\n\tauthor = {Bartels, Pia and Cucherousset, Julien and Gudasz, Cristian and Jansson, Mats and Karlsson, Jan and Persson, Lennart and Premke, Katrin and Rubach, Anja and Steger, Kristin and Tranvik, Lars J. and Eklov, Peter},\n\tmonth = mar,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Aquatic-terrestrial linkage, Autochthonous, Cross-ecosystem, allochthonous, benthic, benthic algae, c-13 addition, clear-water lakes, dissolved organic-carbon, fresh-water, northern sweden, resource use, stable-isotope analysis, support, zooplankton},\n\tpages = {807--818},\n}\n\n\n\n\n\n Cross-ecosystem movements of material and energy are ubiquitous. Aquatic ecosystems typically receive material that also includes organic matter from the surrounding catchment. Terrestrial-derived (allochthonous) organic matter can enter aquatic ecosystems in dissolved or particulate form. Several studies have highlighted the importance of dissolved organic carbon to aquatic consumers, but less is known about allochthonous particulate organic carbon (POC). Similarly, most studies showing the effects of allochthonous organic carbon (OC) on aquatic consumers have investigated pelagic habitats; the effects of allochthonous OC on benthic communities are less well studied. Allochthonous inputs might further decrease primary production through light reduction, thereby potentially affecting autotrophic resource availability to consumers. Here, an enclosure experiment was carried out to test the importance of POC input and light availability on the resource use in a benthic food web of a clear-water lake. Corn starch (a C-4 plant) was used as a POC source due to its insoluble nature and its distinct carbon stable isotope value (delta C-13). The starch carbon was closely dispersed over the bottom of the enclosures to study the fate of a POC source exclusively available to sediment biota. The addition of starch carbon resulted in a clear shift in the isotopic signature of surface-dwelling herbivorous and predatory invertebrates. Although the starch carbon was added solely to the sediment surface, the carbon originating from the starch reached zooplankton. We suggest that allochthonous POC can subsidize benthic food webs directly and can be further transferred to pelagic systems, thereby highlighting the importance of benthic pathways for pelagic habitats.\n
\n\n\n\n \n\n \n \n \n \n \n \n Net ecosystem production in clear-water and brown-water lakes.\n \n \n \n \n\n\n \n Ask, J.; Karlsson, J.; and Jansson, M.\n\n\n \n\n\n\n Global Biogeochemical Cycles, 26(1): GB1017. March 2012.\n 00039\n\n\n\n
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\n\n\n@article{ask_net_2012,\n\ttitle = {Net ecosystem production in clear-water and brown-water lakes},\n\tvolume = {26},\n\tissn = {1944-9224},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2010GB003951/abstract},\n\tdoi = {10.1029/2010GB003951},\n\tabstract = {We studied 15 lakes in northern Sweden with respect to primary production and respiration in benthic and pelagic habitats. The lakes were characterized by different concentrations of colored dissolved organic carbon (DOC) of terrestrial origin, forming a gradient ranging from clear-water to brown-water lakes. Primary production decreased and respiration increased on a whole-lake scale along the gradient of increasing DOC. Thus, the lakes became more net heterotrophic, i.e., had lower net ecosystem production (NEP = gross primary production – community respiration), with increasing terrestrial DOC and this change coincided with increasing partial pressure of carbon dioxide (pCO2) in the surface waters. The single most important process for the increasing net heterotrophy along the DOC gradient was pelagic respiration of terrestrial organic carbon. In spite of high metabolic activity in the benthic habitat, benthic primary production and benthic respiration decreased simultaneously with increasing DOC, showing that the benthic habitat was in metabolic balance throughout the gradient. Therefore, the net heterotrophic states of the lakes depended on the terrestrial DOC export to lakes and the concomitant respiration of terrestrial organic carbon in the pelagic habitat.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-06},\n\tjournal = {Global Biogeochemical Cycles},\n\tauthor = {Ask, Jenny and Karlsson, Jan and Jansson, Mats},\n\tmonth = mar,\n\tyear = {2012},\n\tnote = {00039},\n\tkeywords = {\\#nosource, 0408 Benthic processes, 0458 Limnology, Benthic processes, DOC, Limnology, benthic, lake metabolism, pelagic, primary production, respiration},\n\tpages = {GB1017},\n}\n\n\n\n\n\n We studied 15 lakes in northern Sweden with respect to primary production and respiration in benthic and pelagic habitats. The lakes were characterized by different concentrations of colored dissolved organic carbon (DOC) of terrestrial origin, forming a gradient ranging from clear-water to brown-water lakes. Primary production decreased and respiration increased on a whole-lake scale along the gradient of increasing DOC. Thus, the lakes became more net heterotrophic, i.e., had lower net ecosystem production (NEP = gross primary production – community respiration), with increasing terrestrial DOC and this change coincided with increasing partial pressure of carbon dioxide (pCO2) in the surface waters. The single most important process for the increasing net heterotrophy along the DOC gradient was pelagic respiration of terrestrial organic carbon. In spite of high metabolic activity in the benthic habitat, benthic primary production and benthic respiration decreased simultaneously with increasing DOC, showing that the benthic habitat was in metabolic balance throughout the gradient. Therefore, the net heterotrophic states of the lakes depended on the terrestrial DOC export to lakes and the concomitant respiration of terrestrial organic carbon in the pelagic habitat.\n
\n\n\n\n \n\n \n \n \n \n \n The influence of non-sorted circles on species diversity of vascular plants, bryophytes and lichens in Sub-Arctic Tundra.\n \n \n \n\n\n \n Makoto, K.; and Klaminder, J.\n\n\n \n\n\n\n Polar Biology, 35(11): 1659–1667. November 2012.\n 00018\n\n\n\n
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\n\n\n@article{makoto_influence_2012,\n\ttitle = {The influence of non-sorted circles on species diversity of vascular plants, bryophytes and lichens in {Sub}-{Arctic} {Tundra}},\n\tvolume = {35},\n\tissn = {0722-4060},\n\tdoi = {10.1007/s00300-012-1206-3},\n\tabstract = {Non-sorted circles (NSCs), also known as frost boils, are common soil frost features that create a small-scale mosaic of vegetation zones in periglacial landscapes. The causes of variation in plant diversity within NSCs are poorly understood. This lack of understanding hampers our ability to predict how arctic plant communities respond to changing soil frost conditions. We hypothesised that plant communities of different ages develop at a micro-site scale within NSCs as soil frost periodically exposes uncolonised soil or fatally offsets plant succession. To test this hypothesis, we investigated the species diversity of plant communities (vascular plants, bryophytes and lichens) from the sparsely vegetated centre of the circles to the densely vegetated outer domain in conjunction with estimates of the age of the plant communities (inferred using lichenometry). Our results suggest that the variation in species diversity and density can largely be explained by the occurrence of progressively older plant communities from the centre towards the vegetated rim. Here, the high species diversity was observed to occur in communities having the ages approximately around 150 years. Our findings suggest that soil frost disturbances are important for maintaining successional gradients several centuries long within the arctic landscape at a small spatial scale ({\\textless} 3 m). The termination of soil frost activity as a result of a warmer future winter climate is therefore most likely to result in a loss of micro-sites having young vegetation communities with high plant diversities and a subsequent establishment of mature shrub-dominated plant communities.},\n\tlanguage = {English},\n\tnumber = {11},\n\tjournal = {Polar Biology},\n\tauthor = {Makoto, K. and Klaminder, J.},\n\tmonth = nov,\n\tyear = {2012},\n\tnote = {00018},\n\tkeywords = {\\#nosource, Cryoturbation, Ecosystems, Frost boil, Periglacial process, Plant species diversity, alaska, bioclimate gradient, climate change, communities, forms, growth-response, manipulations, northern sweden, removal, vegetation},\n\tpages = {1659--1667},\n}\n\n\n\n\n\n Non-sorted circles (NSCs), also known as frost boils, are common soil frost features that create a small-scale mosaic of vegetation zones in periglacial landscapes. The causes of variation in plant diversity within NSCs are poorly understood. This lack of understanding hampers our ability to predict how arctic plant communities respond to changing soil frost conditions. We hypothesised that plant communities of different ages develop at a micro-site scale within NSCs as soil frost periodically exposes uncolonised soil or fatally offsets plant succession. To test this hypothesis, we investigated the species diversity of plant communities (vascular plants, bryophytes and lichens) from the sparsely vegetated centre of the circles to the densely vegetated outer domain in conjunction with estimates of the age of the plant communities (inferred using lichenometry). Our results suggest that the variation in species diversity and density can largely be explained by the occurrence of progressively older plant communities from the centre towards the vegetated rim. Here, the high species diversity was observed to occur in communities having the ages approximately around 150 years. Our findings suggest that soil frost disturbances are important for maintaining successional gradients several centuries long within the arctic landscape at a small spatial scale (\\textless 3 m). The termination of soil frost activity as a result of a warmer future winter climate is therefore most likely to result in a loss of micro-sites having young vegetation communities with high plant diversities and a subsequent establishment of mature shrub-dominated plant communities.\n
\n\n\n\n \n\n \n \n \n \n \n Transfer of bacterial production based on labile carbon to higher trophic levels in an oligotrophic pelagic system.\n \n \n \n\n\n \n Faithfull, C.; Huss, M.; Vrede, T.; Karlsson, J.; and Bergström, A.\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences, 69(1): 85–93. January 2012.\n 00020\n\n\n\n
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\n\n\n@article{faithfull_transfer_2012,\n\ttitle = {Transfer of bacterial production based on labile carbon to higher trophic levels in an oligotrophic pelagic system},\n\tvolume = {69},\n\tissn = {0706-652X},\n\tdoi = {10.1139/F2011-142},\n\tabstract = {Additions of labile organic carbon (C) enhanced bacterial production (BP) and were associated with increases in crustacean zooplankton and planktivorous fish biomasses. This was shown in a mesocosm experiment where we traced the contribution of BP to zooplankton and fish using stable isotopes and labile glucose-C as a biomarker. BP increased with glucose-C addition, and all zooplankton and fish incorporated some glucose-C. However, the effect of labile-C addition on zooplankton was taxa-dependant, as although cladocerans incorporated the most labile-C, increased BP did not affect cladoceran biomass. Instead, calanoid copepod biomass increased with glucose addition. This suggests that the ability to selectively graze on high quality food, such as bacterial grazing protists capable of trophic upgrading, had a stronger positive effect on calanoid copepods biomass than unselective grazing on bacteria and protists had on cladoceran biomass. Higher BP was associated with increased survival and population growth of young-of-the-year perch (Perca fluviatilis) when stocked at high densities, which suggested that BP had a density-dependant positive effect on fish growth.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Faithfull, Carolyn and Huss, Magnus and Vrede, Tobias and Karlsson, Jan and Bergström, Ann-Kristin},\n\tmonth = jan,\n\tyear = {2012},\n\tnote = {00020},\n\tkeywords = {\\#nosource, cladocerans, dissolved organic-carbon, efficiency, fatty-acids, lake, matter, microbial food-web, phytoplankton, taxonomic composition, zooplankton production},\n\tpages = {85--93},\n}\n\n\n\n\n\n Additions of labile organic carbon (C) enhanced bacterial production (BP) and were associated with increases in crustacean zooplankton and planktivorous fish biomasses. This was shown in a mesocosm experiment where we traced the contribution of BP to zooplankton and fish using stable isotopes and labile glucose-C as a biomarker. BP increased with glucose-C addition, and all zooplankton and fish incorporated some glucose-C. However, the effect of labile-C addition on zooplankton was taxa-dependant, as although cladocerans incorporated the most labile-C, increased BP did not affect cladoceran biomass. Instead, calanoid copepod biomass increased with glucose addition. This suggests that the ability to selectively graze on high quality food, such as bacterial grazing protists capable of trophic upgrading, had a stronger positive effect on calanoid copepods biomass than unselective grazing on bacteria and protists had on cladoceran biomass. Higher BP was associated with increased survival and population growth of young-of-the-year perch (Perca fluviatilis) when stocked at high densities, which suggested that BP had a density-dependant positive effect on fish growth.\n
\n\n\n\n \n\n \n \n \n \n \n Terrestrial organic matter support of lake food webs: Evidence from lake metabolism and stable hydrogen isotopes of consumers.\n \n \n \n\n\n \n Karlsson, J.; Berggren, M.; Ask, J.; Byström, P.; Jonsson, A.; Laudon, H.; and Jansson, M.\n\n\n \n\n\n\n Limnology and Oceanography, 57(4): 1042–1048. July 2012.\n \n\n\n\n
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\n\n\n@article{karlsson_terrestrial_2012,\n\ttitle = {Terrestrial organic matter support of lake food webs: {Evidence} from lake metabolism and stable hydrogen isotopes of consumers},\n\tvolume = {57},\n\tissn = {0024-3590},\n\tshorttitle = {Terrestrial organic matter support of lake food webs},\n\tdoi = {10.4319/lo.2012.57.4.1042},\n\tabstract = {We quantified the utilization of terrestrial organic matter (OM) in the food web of a humic lake by analyzing the metabolism and the consumers' stable isotopic (C, H, N) composition in benthic and pelagic habitats. Terrestrial OM inputs (3 g C m(-2) d(-1)) to the lake greatly exceeded autochthonous OM production (3 mg C m(-2) d(-1)) in the lake. Heterotrophic bacterial growth (19 mg C m(-2) d(-1)) and community respiration (115 mg C m(-2) d(-1)) were high relative to algal photosynthesis and were predominantly ({\\textgreater} 85\\%) supported by terrestrial OM in both habitats. Consequently, terrestrial OM fueled most (85\\%) of the total production at the base of the lake's food web (i.e., the sum of primary and bacterial production). Despite the uncertainties of quantitatively estimating resource use based on stable isotopes, terrestrial OM clearly also supported around half the zooplankton (47\\%), macrozoobenthos (63\\%), and fish (57\\%) biomass. These results indicate that, although rates of terrestrial OM inputs were around three orders of magnitude greater than that of autochthonous OM production, the use of the two resources by higher trophic levels was roughly equal. The disproportionally low reliance on terrestrial OM at higher trophic levels, compared with its high rates of input and high support of basic biomass production in the lake, suggests that autochthonous resources could not be completely replaced by terrestrial resources and indicates an upper limit to terrestrial support of lake food webs.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Karlsson, Jan and Berggren, Martin and Ask, Jenny and Byström, Pär and Jonsson, Anders and Laudon, Hjalmar and Jansson, Mats},\n\tmonth = jul,\n\tyear = {2012},\n\tkeywords = {\\#nosource, allochthonous carbon, aquatic consumers, bacterial production, boreal lakes, c-13 addition, humic lakes, northern sweden, phytoplankton, secondary production, zooplankton},\n\tpages = {1042--1048},\n}\n\n\n\n\n\n We quantified the utilization of terrestrial organic matter (OM) in the food web of a humic lake by analyzing the metabolism and the consumers' stable isotopic (C, H, N) composition in benthic and pelagic habitats. Terrestrial OM inputs (3 g C m(-2) d(-1)) to the lake greatly exceeded autochthonous OM production (3 mg C m(-2) d(-1)) in the lake. Heterotrophic bacterial growth (19 mg C m(-2) d(-1)) and community respiration (115 mg C m(-2) d(-1)) were high relative to algal photosynthesis and were predominantly (\\textgreater 85%) supported by terrestrial OM in both habitats. Consequently, terrestrial OM fueled most (85%) of the total production at the base of the lake's food web (i.e., the sum of primary and bacterial production). Despite the uncertainties of quantitatively estimating resource use based on stable isotopes, terrestrial OM clearly also supported around half the zooplankton (47%), macrozoobenthos (63%), and fish (57%) biomass. These results indicate that, although rates of terrestrial OM inputs were around three orders of magnitude greater than that of autochthonous OM production, the use of the two resources by higher trophic levels was roughly equal. The disproportionally low reliance on terrestrial OM at higher trophic levels, compared with its high rates of input and high support of basic biomass production in the lake, suggests that autochthonous resources could not be completely replaced by terrestrial resources and indicates an upper limit to terrestrial support of lake food webs.\n
\n\n\n\n \n\n \n \n \n \n \n \n Preservation effects on C/N ratios and stable isotope signatures of freshwater fishes and benthic macroinvertebrates.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n Limnology and Oceanography: Methods, 10(2): 75–89. February 2012.\n 00008\n\n\n\n
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\n\n\n@article{lau_preservation_2012,\n\ttitle = {Preservation effects on {C}/{N} ratios and stable isotope signatures of freshwater fishes and benthic macroinvertebrates},\n\tvolume = {10},\n\tissn = {1541-5856},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.4319/lom.2012.10.75/abstract},\n\tdoi = {10.4319/lom.2012.10.75},\n\tabstract = {This study examined the effects of fluid preservatives on carbon and nitrogen stable isotopes (δ13C and δ15N) and C/N ratios of freshwater animals. Brotia hainanensis snails, Caridina cantonensis and Macrobrachium hainanense shrimps, and Pseudogastromyzon myersi, Liniparhomaloptera disparis, and Ctenogobius duospilus fishes were collected from seven Hong Kong streams, so as to incorporate natural variations in isotopic signals among conspecifics. Samples were preserved with 10\\% formalin, 70\\% ethanol, or formalin-ethanol solution (fixation in formalin then storage in ethanol). We compared sample molar C/N, δ13C, and δ15N with frozen conspecifics after 30, 60, 90, 180, and 360 d. Increases in C/N were evident in formalin-fixed shrimps and fish only, whereas ΔC/N attributable to ethanol and formalin-ethanol preservation was insignificant in all species. Chemical preservation generally caused δ13C depletion in fishes and Δδ13C significantly declined over time in formalin-ethanol-preserved L. disparis. Formalin-induced δ13C shifts were observed in shrimps (C. cantonensis: −1.54‰; M. hainanense: −0.80‰) and snails (−0.25‰) and were relatively consistent when preservation was ≤ 60 d. The influence of formalin-ethanol on C/N and δ13C was smaller than that of formalin for all species and more consistent than ethanol preservation. δ15N of all species was unaffected (within ±1‰) by chemical preservation. Effects on isotopic signals were more predictable among fishes than shrimps or snails. Corrections of +1.11‰ and +1.24‰ should be applied to δ13C of fishes preserved with formalin and formalin-ethanol (respectively) during trophic analysis. We recommend using formalin-ethanol for macroinvertebrates to limit isotopic shifts, especially those preserved for {\\textgreater} 60 d.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-05-27},\n\tjournal = {Limnology and Oceanography: Methods},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y. and Dudgeon, David},\n\tmonth = feb,\n\tyear = {2012},\n\tnote = {00008},\n\tkeywords = {\\#nosource},\n\tpages = {75--89},\n}\n\n\n\n\n\n This study examined the effects of fluid preservatives on carbon and nitrogen stable isotopes (δ13C and δ15N) and C/N ratios of freshwater animals. Brotia hainanensis snails, Caridina cantonensis and Macrobrachium hainanense shrimps, and Pseudogastromyzon myersi, Liniparhomaloptera disparis, and Ctenogobius duospilus fishes were collected from seven Hong Kong streams, so as to incorporate natural variations in isotopic signals among conspecifics. Samples were preserved with 10% formalin, 70% ethanol, or formalin-ethanol solution (fixation in formalin then storage in ethanol). We compared sample molar C/N, δ13C, and δ15N with frozen conspecifics after 30, 60, 90, 180, and 360 d. Increases in C/N were evident in formalin-fixed shrimps and fish only, whereas ΔC/N attributable to ethanol and formalin-ethanol preservation was insignificant in all species. Chemical preservation generally caused δ13C depletion in fishes and Δδ13C significantly declined over time in formalin-ethanol-preserved L. disparis. Formalin-induced δ13C shifts were observed in shrimps (C. cantonensis: −1.54‰; M. hainanense: −0.80‰) and snails (−0.25‰) and were relatively consistent when preservation was ≤ 60 d. The influence of formalin-ethanol on C/N and δ13C was smaller than that of formalin for all species and more consistent than ethanol preservation. δ15N of all species was unaffected (within ±1‰) by chemical preservation. Effects on isotopic signals were more predictable among fishes than shrimps or snails. Corrections of +1.11‰ and +1.24‰ should be applied to δ13C of fishes preserved with formalin and formalin-ethanol (respectively) during trophic analysis. We recommend using formalin-ethanol for macroinvertebrates to limit isotopic shifts, especially those preserved for \\textgreater 60 d.\n
\n\n\n\n \n\n \n \n \n \n \n \n Fatty acid composition of consumers in boreal lakes – variation across species, space and time.\n \n \n \n \n\n\n \n Lau, D. C. P.; Vrede, T.; Pickova, J.; and Goedkoop, W.\n\n\n \n\n\n\n Freshwater Biology, 57(1): 24–38. January 2012.\n \n\n\n\n
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\n\n\n@article{lau_fatty_2012,\n\ttitle = {Fatty acid composition of consumers in boreal lakes – variation across species, space and time},\n\tvolume = {57},\n\tissn = {1365-2427},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1365-2427.2011.02690.x/abstract},\n\tdoi = {10.1111/j.1365-2427.2011.02690.x},\n\tabstract = {1. Fatty acids (FAs) have been widely applied as trophic biomarkers in aquatic food web studies. However, current knowledge of inter- and intraspecific variation in consumer FA compositions across spatial and temporal scales is constrained to a few pelagic taxa. 2. We analysed the FAs of 22 taxa of benthic macroinvertebrates, zooplankton and fish collected from the littoral, pelagic and profundal habitats of nine boreal oligotrophic lakes over spring, summer and autumn. We quantified and compared the FA variance partitions contributed by species identity (i.e. an integrative effect of phylogenetic origin, life history and functional feeding guild of individual taxa), site and season using partial redundancy analysis both on all consumers and on benthic arthropods alone. 3. Species identity alone contributed 84.4 and 72.8\\% of explained FA variation of all consumers and benthic arthropods, respectively. Influences of site, season and all joint effects accounted for 0–11.3\\% only. Fatty acid profiles of primary consumers differentiated below class level, but those of predators were distinguishable only when they became more taxonomically distinct (i.e. among classes or higher). 4. Pelagic and profundal consumers showed stronger reliance on autochthonous resources than did their littoral counterparts as reflected by their higher ω3 to ω6 FA ratios. Polyunsaturated FAs (PUFAs) were increasingly retained with trophic levels, and saturated FAs (e.g. FA 16 : 0) gradually reduced. Ecologically, this trade-off enhances the trophic transfer efficiency and confirms the importance of PUFA-rich autotrophs in aquatic food webs. 5. Our findings indicate strong interspecific differences in FA requirements and assimilation among aquatic consumers from a wide range of taxonomic levels, habitats and lakes. Consumers were able to maintain homoeostasis in FA compositions across spatial and temporal changes in resource FAs, but consumer homoeostasis did not limit the effectiveness of FAs as trophic biomarkers.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-05-27},\n\tjournal = {Freshwater Biology},\n\tauthor = {Lau, Danny C. P. and Vrede, Tobias and Pickova, Jana and Goedkoop, Willem},\n\tmonth = jan,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Biomarkers, Trophic transfer, fish, food web, macroinvertebrates, polyunsaturated fatty acids, zooplankton},\n\tpages = {24--38},\n}\n\n\n\n\n\n 1. Fatty acids (FAs) have been widely applied as trophic biomarkers in aquatic food web studies. However, current knowledge of inter- and intraspecific variation in consumer FA compositions across spatial and temporal scales is constrained to a few pelagic taxa. 2. We analysed the FAs of 22 taxa of benthic macroinvertebrates, zooplankton and fish collected from the littoral, pelagic and profundal habitats of nine boreal oligotrophic lakes over spring, summer and autumn. We quantified and compared the FA variance partitions contributed by species identity (i.e. an integrative effect of phylogenetic origin, life history and functional feeding guild of individual taxa), site and season using partial redundancy analysis both on all consumers and on benthic arthropods alone. 3. Species identity alone contributed 84.4 and 72.8% of explained FA variation of all consumers and benthic arthropods, respectively. Influences of site, season and all joint effects accounted for 0–11.3% only. Fatty acid profiles of primary consumers differentiated below class level, but those of predators were distinguishable only when they became more taxonomically distinct (i.e. among classes or higher). 4. Pelagic and profundal consumers showed stronger reliance on autochthonous resources than did their littoral counterparts as reflected by their higher ω3 to ω6 FA ratios. Polyunsaturated FAs (PUFAs) were increasingly retained with trophic levels, and saturated FAs (e.g. FA 16 : 0) gradually reduced. Ecologically, this trade-off enhances the trophic transfer efficiency and confirms the importance of PUFA-rich autotrophs in aquatic food webs. 5. Our findings indicate strong interspecific differences in FA requirements and assimilation among aquatic consumers from a wide range of taxonomic levels, habitats and lakes. Consumers were able to maintain homoeostasis in FA compositions across spatial and temporal changes in resource FAs, but consumer homoeostasis did not limit the effectiveness of FAs as trophic biomarkers.\n
\n\n\n\n \n\n \n \n \n \n \n \n Developing a circumpolar monitoring framework for Arctic freshwater biodiversity.\n \n \n \n \n\n\n \n Culp, J. M.; Lento, J.; Goedkoop, W.; Power, M.; Rautio, M.; Christoffersen, K. S.; Guðbergsson, G.; Lau, D.; Liljaniemi, P.; Sandøy, S.; and Svoboda, M.\n\n\n \n\n\n\n Biodiversity, 13(3-4): 215–227. September 2012.\n 00009\n\n\n\n
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\n\n\n@article{culp_developing_2012,\n\ttitle = {Developing a circumpolar monitoring framework for {Arctic} freshwater biodiversity},\n\tvolume = {13},\n\tissn = {1488-8386},\n\turl = {http://dx.doi.org/10.1080/14888386.2012.717526},\n\tdoi = {10.1080/14888386.2012.717526},\n\tabstract = {Arctic freshwater ecosystems are facing unique challenges through the interaction of natural and human-induced stressors such as climate change and industrial development. Much is unknown about the biodiversity of Arctic freshwaters, although it is believed to have already been affected by climate change. A pan-Arctic monitoring strategy is critically needed to improve abilities to detect and understand ongoing and future changes in Arctic freshwater ecosystems. The challenging issues that Arctic freshwater monitoring must address include: the large diversity of Arctic freshwater ecosystems, varying levels of stressor impacts across the Arctic, lack of historical baseline research and monitoring coordination, and poor among-country standardization of sampling protocols. In response, the Arctic Council's Freshwater Expert Monitoring Group of the Circumpolar Biodiversity Monitoring Program (Conservation of Arctic Flora and Fauna) is developing a framework for monitoring Arctic freshwater biodiversity that will lead to regular reviews of the state of freshwater ecosystems across the circumpolar Arctic. The parameters of primary focus for the monitoring framework are classified by focal ecosystem components (FECs), which are biotic or abiotic factors that are ecologically pivotal, charismatic and/or sensitive to changes in biodiversity. FECs are placed in the context of expected ecosystem change through the development of testable impact hypotheses (or predictions) that outline a cause-effect framework regarding how change in environmental and anthropogenic stressors is expected to affect FECs. These prediction statements provide both guidelines for future scientific data collection and a focus for management decision-making. Here we discuss the design of a proposed monitoring framework and the development of impact hypotheses that focus on climate change effects. We emphasise the connectivity between science, monitoring and management necessary to implement the framework across the Arctic.},\n\tnumber = {3-4},\n\turldate = {2017-05-27},\n\tjournal = {Biodiversity},\n\tauthor = {Culp, Joseph M. and Lento, Jennifer and Goedkoop, Willem and Power, Michael and Rautio, Milla and Christoffersen, Kirsten S. and Guðbergsson, Guðni and Lau, Danny and Liljaniemi, Petri and Sandøy, Steinar and Svoboda, Michael},\n\tmonth = sep,\n\tyear = {2012},\n\tnote = {00009},\n\tkeywords = {\\#nosource, Arctic, Biodiversity, Monitoring, aquatic fauna, aquatic flora, climate change, decision-making, freshwater},\n\tpages = {215--227},\n}\n\n\n\n\n\n Arctic freshwater ecosystems are facing unique challenges through the interaction of natural and human-induced stressors such as climate change and industrial development. Much is unknown about the biodiversity of Arctic freshwaters, although it is believed to have already been affected by climate change. A pan-Arctic monitoring strategy is critically needed to improve abilities to detect and understand ongoing and future changes in Arctic freshwater ecosystems. The challenging issues that Arctic freshwater monitoring must address include: the large diversity of Arctic freshwater ecosystems, varying levels of stressor impacts across the Arctic, lack of historical baseline research and monitoring coordination, and poor among-country standardization of sampling protocols. In response, the Arctic Council's Freshwater Expert Monitoring Group of the Circumpolar Biodiversity Monitoring Program (Conservation of Arctic Flora and Fauna) is developing a framework for monitoring Arctic freshwater biodiversity that will lead to regular reviews of the state of freshwater ecosystems across the circumpolar Arctic. The parameters of primary focus for the monitoring framework are classified by focal ecosystem components (FECs), which are biotic or abiotic factors that are ecologically pivotal, charismatic and/or sensitive to changes in biodiversity. FECs are placed in the context of expected ecosystem change through the development of testable impact hypotheses (or predictions) that outline a cause-effect framework regarding how change in environmental and anthropogenic stressors is expected to affect FECs. These prediction statements provide both guidelines for future scientific data collection and a focus for management decision-making. Here we discuss the design of a proposed monitoring framework and the development of impact hypotheses that focus on climate change effects. We emphasise the connectivity between science, monitoring and management necessary to implement the framework across the Arctic.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plot-scale evidence of tundra vegetation change and links to recent summer warming.\n \n \n \n \n\n\n \n Elmendorf, S. C.; Henry, G. H. R.; Hollister, R. D.; Björk, R. G.; Boulanger-Lapointe, N.; Cooper, E. J.; Cornelissen, J. H. C.; Day, T. A.; Dorrepaal, E.; Elumeeva, T. G.; Gill, M.; Gould, W. A.; Harte, J.; Hik, D. S.; Hofgaard, A.; Johnson, D. R.; Johnstone, J. F.; Jónsdóttir, I. S.; Jorgenson, J. C.; Klanderud, K.; Klein, J. A.; Koh, S.; Kudo, G.; Lara, M.; Lévesque, E.; Magnússon, B.; May, J. L.; Mercado-Dı´az, J. A.; Michelsen, A.; Molau, U.; Myers-Smith, I. H.; Oberbauer, S. F.; Onipchenko, V. G.; Rixen, C.; Martin Schmidt, N.; Shaver, G. R.; Spasojevic, M. J.; Þórhallsdóttir, Þ. E.; Tolvanen, A.; Troxler, T.; Tweedie, C. E.; Villareal, S.; Wahren, C.; Walker, X.; Webber, P. J.; Welker, J. M.; and Wipf, S.\n\n\n \n\n\n\n Nature Climate Change, 2(6): 453–457. June 2012.\n \n\n\n\n
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\n\n\n@article{elmendorf_plot-scale_2012,\n\ttitle = {Plot-scale evidence of tundra vegetation change and links to recent summer warming},\n\tvolume = {2},\n\tcopyright = {© 2012 Nature Publishing Group},\n\tissn = {1758-678X},\n\turl = {http://www.nature.com/nclimate/journal/v2/n6/abs/nclimate1465.html},\n\tdoi = {10.1038/nclimate1465},\n\tabstract = {Temperature is increasing at unprecedented rates across most of the tundra biome. Remote-sensing data indicate that contemporary climate warming has already resulted in increased productivity over much of the Arctic, but plot-based evidence for vegetation transformation is not widespread. We analysed change in tundra vegetation surveyed between 1980 and 2010 in 158 plant communities spread across 46 locations. We found biome-wide trends of increased height of the plant canopy and maximum observed plant height for most vascular growth forms; increased abundance of litter; increased abundance of evergreen, low-growing and tall shrubs; and decreased abundance of bare ground. Intersite comparisons indicated an association between the degree of summer warming and change in vascular plant abundance, with shrubs, forbs and rushes increasing with warming. However, the association was dependent on the climate zone, the moisture regime and the presence of permafrost. Our data provide plot-scale evidence linking changes in vascular plant abundance to local summer warming in widely dispersed tundra locations across the globe.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-07},\n\tjournal = {Nature Climate Change},\n\tauthor = {Elmendorf, Sarah C. and Henry, Gregory H. R. and Hollister, Robert D. and Björk, Robert G. and Boulanger-Lapointe, Noémie and Cooper, Elisabeth J. and Cornelissen, Johannes H. C. and Day, Thomas A. and Dorrepaal, Ellen and Elumeeva, Tatiana G. and Gill, Mike and Gould, William A. and Harte, John and Hik, David S. and Hofgaard, Annika and Johnson, David R. and Johnstone, Jill F. and Jónsdóttir, Ingibjörg Svala and Jorgenson, Janet C. and Klanderud, Kari and Klein, Julia A. and Koh, Saewan and Kudo, Gaku and Lara, Mark and Lévesque, Esther and Magnússon, Borgthor and May, Jeremy L. and Mercado-Dı´az, Joel A. and Michelsen, Anders and Molau, Ulf and Myers-Smith, Isla H. and Oberbauer, Steven F. and Onipchenko, Vladimir G. and Rixen, Christian and Martin Schmidt, Niels and Shaver, Gaius R. and Spasojevic, Marko J. and Þórhallsdóttir, Þóra Ellen and Tolvanen, Anne and Troxler, Tiffany and Tweedie, Craig E. and Villareal, Sandra and Wahren, Carl-Henrik and Walker, Xanthe and Webber, Patrick J. and Welker, Jeffrey M. and Wipf, Sonja},\n\tmonth = jun,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Conservation, Conservation biology, Impacts, Plant ecology, climate change, ecology},\n\tpages = {453--457},\n}\n\n\n\n\n\n Temperature is increasing at unprecedented rates across most of the tundra biome. Remote-sensing data indicate that contemporary climate warming has already resulted in increased productivity over much of the Arctic, but plot-based evidence for vegetation transformation is not widespread. We analysed change in tundra vegetation surveyed between 1980 and 2010 in 158 plant communities spread across 46 locations. We found biome-wide trends of increased height of the plant canopy and maximum observed plant height for most vascular growth forms; increased abundance of litter; increased abundance of evergreen, low-growing and tall shrubs; and decreased abundance of bare ground. Intersite comparisons indicated an association between the degree of summer warming and change in vascular plant abundance, with shrubs, forbs and rushes increasing with warming. However, the association was dependent on the climate zone, the moisture regime and the presence of permafrost. Our data provide plot-scale evidence linking changes in vascular plant abundance to local summer warming in widely dispersed tundra locations across the globe.\n
\n\n\n\n \n\n \n \n \n \n \n \n Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (α-FeOOH) nanoparticles.\n \n \n \n \n\n\n \n Persson, P.; Andersson, T.; Nelson, H.; Sjöberg, S.; Giesler, R.; and Lövgren, L.\n\n\n \n\n\n\n Journal of Colloid and Interface Science, 386(1): 350–358. November 2012.\n \n\n\n\n
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\n\n\n@article{persson_surface_2012,\n\ttitle = {Surface complexes of monomethyl phosphate stabilized by hydrogen bonding on goethite (α-{FeOOH}) nanoparticles},\n\tvolume = {386},\n\tissn = {0021-9797},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0021979712008181},\n\tdoi = {10.1016/j.jcis.2012.07.042},\n\tabstract = {Typically, a significant fraction of phosphorus in soils is composed of organic phosphates, and this fraction thus plays an important role in the global phosphorus cycle. Here we have studied adsorption of monomethyl phosphate (MMP) to goethite (α-FeOOH) as a model system in order to better understand the mechanisms behind adsorption of organic phosphates to soil minerals, and how adsorption affects the stability of these molecules. The adsorption reactions and stability of MMP on goethite were studied at room temperature as a function of pH, time and total concentration of MMP by means of quantitative batch experiments, potentiometry and infrared spectroscopy. MMP was found to be stable at the water–goethite interface within the pH region 3–9 and over extended periods of time, as well as in solution. The infrared spectra indicated that MMP formed three predominating pH-dependent surface complexes on goethite, and that these interacted monodentately with surface Fe. The complexes differed in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The presented surface complexation model was based on the collective spectroscopic and macroscopic results, using the Basic Stern approach to describe the interfacial region. The model consisted of three monodentate inner sphere surface complexes where the MMP complexes were stabilized by hydrogen bonding to a neighboring surface site. The three complexes, which had equal proton content and thus could be defined as surface isomers, were distinguished by the distribution of charge over the 0-plane and β-plane. In the high pH-range, MMP acted as a hydrogen bond acceptor whereas it was a hydrogen bond donor at low pH.},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Colloid and Interface Science},\n\tauthor = {Persson, Per and Andersson, Tove and Nelson, Hanna and Sjöberg, Staffan and Giesler, Reiner and Lövgren, Lars},\n\tmonth = nov,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Adsorption, Goethite, Hydrogen bonding, Infrared spectroscopy Basic Stern Model, Monomethyl phosphate, Surface complexation, Surface isomers},\n\tpages = {350--358},\n}\n\n\n\n\n\n Typically, a significant fraction of phosphorus in soils is composed of organic phosphates, and this fraction thus plays an important role in the global phosphorus cycle. Here we have studied adsorption of monomethyl phosphate (MMP) to goethite (α-FeOOH) as a model system in order to better understand the mechanisms behind adsorption of organic phosphates to soil minerals, and how adsorption affects the stability of these molecules. The adsorption reactions and stability of MMP on goethite were studied at room temperature as a function of pH, time and total concentration of MMP by means of quantitative batch experiments, potentiometry and infrared spectroscopy. MMP was found to be stable at the water–goethite interface within the pH region 3–9 and over extended periods of time, as well as in solution. The infrared spectra indicated that MMP formed three predominating pH-dependent surface complexes on goethite, and that these interacted monodentately with surface Fe. The complexes differed in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The presented surface complexation model was based on the collective spectroscopic and macroscopic results, using the Basic Stern approach to describe the interfacial region. The model consisted of three monodentate inner sphere surface complexes where the MMP complexes were stabilized by hydrogen bonding to a neighboring surface site. The three complexes, which had equal proton content and thus could be defined as surface isomers, were distinguished by the distribution of charge over the 0-plane and β-plane. In the high pH-range, MMP acted as a hydrogen bond acceptor whereas it was a hydrogen bond donor at low pH.\n
\n\n\n\n \n\n \n \n \n \n \n \n Reservations about preservations: storage methods affect δ13C signatures differently even in closely related soil fauna.\n \n \n \n \n\n\n \n Krab, E. J.; Van Logtestijn, R. S. P.; Cornelissen, J. H. C.; and Berg, M. P.\n\n\n \n\n\n\n Methods in Ecology and Evolution, 3(1): 138–144. February 2012.\n \n\n\n\n
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\n\n\n@article{krab_reservations_2012,\n\ttitle = {Reservations about preservations: storage methods affect δ{13C} signatures differently even in closely related soil fauna},\n\tvolume = {3},\n\tissn = {2041-210X},\n\tshorttitle = {Reservations about preservations},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.2041-210X.2011.00126.x/abstract},\n\tdoi = {10.1111/j.2041-210X.2011.00126.x},\n\tabstract = {1. Studies of stable isotope signatures can reveal and quantify trophic carbon transfer between organisms. However, preservation of the samples before analysis cannot always be avoided. Some preservation agents are known to alter tissue δ13C values considerably, but we do not yet understand how variation in such preservation artefacts may be determined by variation in body traits of different invertebrate species and life stage. 2. Here, we tested the effect of four different preservation methods on 13C signatures of two morphologically and ecologically distinct springtails, Folsomia candida and Orchesella cincta. These springtails were fed on the fungus Cladosporium cladosporioides grown on either a C3 or a C4 carbon source, resulting in springtails with two contrasting initial δ13C values. Subsequently, these springtails were preserved for 46 days. In addition, a juvenile–adult comparison was made for F. candida. 3. Freeze-drying and subsequent dry storage did not affect 13C signatures of either species; nor did killing springtails with liquid nitrogen and storing them at −80 °C. Preservation in 70\\% ethanol slightly depleted δ13C values of adult F. candida but not of O. cincta. In contrast, storage in saturated salt solution depleted both species considerably. Life stage affected preservation success significantly; storage in 70\\% ethanol depleted adult F. candida but not its juveniles. Initial δ13C values of the springtails did not interact with preservation artefacts, suggesting that the shifts in δ13C values are caused by effects of the preservative on the animal tissue rather than by its remainders. 4. We recommend freeze-drying as a preservation method. However, our results suggest that interspecific differences (e.g. in body size and cuticle thickness) as well as intraspecific difference (e.g. life stage-dependent changes in the proportion of fat reserves) are important determinants of preservation effects on 13C signatures. This makes interpreting stable isotope data obtained from preserved springtails relatively difficult, especially when natural 13C abundances are used to study trophic interactions or interspecific functional differences. We predict that such complications also apply to other invertebrate taxa and types.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-08},\n\tjournal = {Methods in Ecology and Evolution},\n\tauthor = {Krab, Eveline J. and Van Logtestijn, Richard S. P. and Cornelissen, Johannes H. C. and Berg, Matty P.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Collembola, Enrichment, carbon, sample preservation, soil organisms, stable isotopes},\n\tpages = {138--144},\n}\n\n\n\n\n\n 1. Studies of stable isotope signatures can reveal and quantify trophic carbon transfer between organisms. However, preservation of the samples before analysis cannot always be avoided. Some preservation agents are known to alter tissue δ13C values considerably, but we do not yet understand how variation in such preservation artefacts may be determined by variation in body traits of different invertebrate species and life stage. 2. Here, we tested the effect of four different preservation methods on 13C signatures of two morphologically and ecologically distinct springtails, Folsomia candida and Orchesella cincta. These springtails were fed on the fungus Cladosporium cladosporioides grown on either a C3 or a C4 carbon source, resulting in springtails with two contrasting initial δ13C values. Subsequently, these springtails were preserved for 46 days. In addition, a juvenile–adult comparison was made for F. candida. 3. Freeze-drying and subsequent dry storage did not affect 13C signatures of either species; nor did killing springtails with liquid nitrogen and storing them at −80 °C. Preservation in 70% ethanol slightly depleted δ13C values of adult F. candida but not of O. cincta. In contrast, storage in saturated salt solution depleted both species considerably. Life stage affected preservation success significantly; storage in 70% ethanol depleted adult F. candida but not its juveniles. Initial δ13C values of the springtails did not interact with preservation artefacts, suggesting that the shifts in δ13C values are caused by effects of the preservative on the animal tissue rather than by its remainders. 4. We recommend freeze-drying as a preservation method. However, our results suggest that interspecific differences (e.g. in body size and cuticle thickness) as well as intraspecific difference (e.g. life stage-dependent changes in the proportion of fat reserves) are important determinants of preservation effects on 13C signatures. This makes interpreting stable isotope data obtained from preserved springtails relatively difficult, especially when natural 13C abundances are used to study trophic interactions or interspecific functional differences. We predict that such complications also apply to other invertebrate taxa and types.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.\n \n \n \n \n\n\n \n Elmendorf, S. C.; Henry, G. H. R.; Hollister, R. D.; Björk, R. G.; Bjorkman, A. D.; Callaghan, T. V.; Collier, L. S.; Cooper, E. J.; Cornelissen, J. H. C.; Day, T. A.; Fosaa, A. M.; Gould, W. A.; Grétarsdóttir, J.; Harte, J.; Hermanutz, L.; Hik, D. S.; Hofgaard, A.; Jarrad, F.; Jónsdóttir, I. S.; Keuper, F.; Klanderud, K.; Klein, J. A.; Koh, S.; Kudo, G.; Lang, S. I.; Loewen, V.; May, J. L.; Mercado, J.; Michelsen, A.; Molau, U.; Myers-Smith, I. H.; Oberbauer, S. F.; Pieper, S.; Post, E.; Rixen, C.; Robinson, C. H.; Schmidt, N. M.; Shaver, G. R.; Stenström, A.; Tolvanen, A.; Totland, Ø.; Troxler, T.; Wahren, C.; Webber, P. J.; Welker, J. M.; and Wookey, P. A.\n\n\n \n\n\n\n Ecology Letters, 15(2): 164–175. February 2012.\n \n\n\n\n
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\n\n\n@article{elmendorf_global_2012,\n\ttitle = {Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time},\n\tvolume = {15},\n\tcopyright = {© 2011 Blackwell Publishing Ltd/CNRS},\n\tissn = {1461-0248},\n\tshorttitle = {Global assessment of experimental climate warming on tundra vegetation},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1461-0248.2011.01716.x/abstract},\n\tdoi = {10.1111/j.1461-0248.2011.01716.x},\n\tabstract = {Ecology Letters (2011) \nAbstract\nUnderstanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation – and associated ecosystem consequences – have the potential to be much greater than we have observed to date.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2015-10-04},\n\tjournal = {Ecology Letters},\n\tauthor = {Elmendorf, Sarah C. and Henry, Gregory H. R. and Hollister, Robert D. and Björk, Robert G. and Bjorkman, Anne D. and Callaghan, Terry V. and Collier, Laura Siegwart and Cooper, Elisabeth J. and Cornelissen, Johannes H. C. and Day, Thomas A. and Fosaa, Anna Maria and Gould, William A. and Grétarsdóttir, Járngerður and Harte, John and Hermanutz, Luise and Hik, David S. and Hofgaard, Annika and Jarrad, Frith and Jónsdóttir, Ingibjörg Svala and Keuper, Frida and Klanderud, Kari and Klein, Julia A. and Koh, Saewan and Kudo, Gaku and Lang, Simone I. and Loewen, Val and May, Jeremy L. and Mercado, Joel and Michelsen, Anders and Molau, Ulf and Myers-Smith, Isla H. and Oberbauer, Steven F. and Pieper, Sara and Post, Eric and Rixen, Christian and Robinson, Clare H. and Schmidt, Niels Martin and Shaver, Gaius R. and Stenström, Anna and Tolvanen, Anne and Totland, Ørjan and Troxler, Tiffany and Wahren, Carl-Henrik and Webber, Patrick J. and Welker, Jeffery M. and Wookey, Philip A.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Arctic, Plants, alpine, climate warming, long-term experiment, meta-analysis},\n\tpages = {164--175},\n}\n\n\n\n\n\n Ecology Letters (2011) Abstract Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation – and associated ecosystem consequences – have the potential to be much greater than we have observed to date.\n
\n\n\n\n \n\n \n \n \n \n \n \n Flourish or Flush: Effects of Simulated Extreme Rainfall Events on Sphagnum-dwelling Testate Amoebae in a Subarctic Bog (Abisko, Sweden).\n \n \n \n \n\n\n \n Tsyganov, A. N.; Keuper, F.; Aerts, R.; and Beyens, L.\n\n\n \n\n\n\n Microbial Ecology, 65(1): 101–110. September 2012.\n \n\n\n\n
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\n\n\n@article{tsyganov_flourish_2012,\n\ttitle = {Flourish or {Flush}: {Effects} of {Simulated} {Extreme} {Rainfall} {Events} on {Sphagnum}-dwelling {Testate} {Amoebae} in a {Subarctic} {Bog} ({Abisko}, {Sweden})},\n\tvolume = {65},\n\tissn = {0095-3628, 1432-184X},\n\tshorttitle = {Flourish or {Flush}},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1007/s00248-012-0115-x},\n\tdoi = {10.1007/s00248-012-0115-x},\n\tabstract = {Extreme precipitation events are recognised as important drivers of ecosystem responses to climate change and can considerably affect high-latitude ombrotrophic bogs. Therefore, understanding the relationships between increased rainfall and the biotic components of these ecosystems is necessary for an estimation of climate change impacts. We studied overall effects of increased magnitude, intensity and frequency of rainfall on assemblages of Sphagnum-dwelling testate amoebae in a field climate manipulation experiment located in a relatively dry subarctic bog (Abisko, Sweden). The effects of the treatment were estimated using abundance, species diversity and structure of living and empty shell assemblages of testate amoebae in living and decaying layers of Sphagnum. Our results show that increased rainfall reduced the mean abundance and species richness of living testate amoebae. Besides, the treatment affected species structure of both living and empty shell assemblages, reducing proportions of hydrophilous species. The effects are counterintuitive as increased precipitation-related substrate moisture was expected to have opposite effects on testate amoeba assemblages in relatively dry biotopes. Therefore, we conclude that other rainfall-related factors such as increased infiltration rates and frequency of environmental disturbances can also affect testate amoeba assemblages in Sphagnum and that hydrophilous species are particularly sensitive to variation in these environmental variables.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2015-08-22},\n\tjournal = {Microbial Ecology},\n\tauthor = {Tsyganov, Andrey N. and Keuper, Frida and Aerts, Rien and Beyens, Louis},\n\tmonth = sep,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Geoecology/Natural Processes, Microbial Ecology, Microbiology, Nature Conservation, ecology},\n\tpages = {101--110},\n}\n\n\n\n\n\n Extreme precipitation events are recognised as important drivers of ecosystem responses to climate change and can considerably affect high-latitude ombrotrophic bogs. Therefore, understanding the relationships between increased rainfall and the biotic components of these ecosystems is necessary for an estimation of climate change impacts. We studied overall effects of increased magnitude, intensity and frequency of rainfall on assemblages of Sphagnum-dwelling testate amoebae in a field climate manipulation experiment located in a relatively dry subarctic bog (Abisko, Sweden). The effects of the treatment were estimated using abundance, species diversity and structure of living and empty shell assemblages of testate amoebae in living and decaying layers of Sphagnum. Our results show that increased rainfall reduced the mean abundance and species richness of living testate amoebae. Besides, the treatment affected species structure of both living and empty shell assemblages, reducing proportions of hydrophilous species. The effects are counterintuitive as increased precipitation-related substrate moisture was expected to have opposite effects on testate amoeba assemblages in relatively dry biotopes. Therefore, we conclude that other rainfall-related factors such as increased infiltration rates and frequency of environmental disturbances can also affect testate amoeba assemblages in Sphagnum and that hydrophilous species are particularly sensitive to variation in these environmental variables.\n
\n\n\n\n \n\n \n \n \n \n \n \n On the use of weather data in ecological studies along altitudinal and latitudinal gradients.\n \n \n \n \n\n\n \n Graae, B. J.; De Frenne, P.; Kolb, A.; Brunet, J.; Chabrerie, O.; Verheyen, K.; Pepin, N.; Heinken, T.; Zobel, M.; Shevtsova, A.; Nijs, I.; and Milbau, A.\n\n\n \n\n\n\n Oikos, 121(1): 3–19. 2012.\n \n\n\n\n
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\n\n\n@article{graae_use_2012,\n\ttitle = {On the use of weather data in ecological studies along altitudinal and latitudinal gradients},\n\tvolume = {121},\n\tcopyright = {© 2011 The Authors},\n\tissn = {1600-0706},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0706.2011.19694.x/abstract},\n\tdoi = {10.1111/j.1600-0706.2011.19694.x},\n\tabstract = {Global warming has created a need for studies along climatic gradients to assess the effects of temperature on ecological processes. Altitudinal and latitudinal gradients are often used as such, usually in combination with air temperature data from the closest weather station recorded at 1.5–2 m above the ground. However, many ecological processes occur in, at, or right above the soil surface. To evaluate how representative the commonly used weather station data are for the microclimate relevant for soil surface biota, we compared weather station temperatures for an altitudinal (500–900 m a.s.l.) and a latitudinal gradient (49–68°N) with data obtained by temperature sensors placed right below the soil surface at five sites along these gradients. The mean annual temperatures obtained from weather stations and adjusted using a lapse rate of −5.5°C km−1 were between 3.8°C lower and 1.6°C higher than those recorded by the temperature sensors at the soil surface, depending on the position along the gradients. The monthly mean temperatures were up to 10°C warmer or 5°C colder at the soil surface. The within-site variation in accumulated temperature was as high as would be expected from a 300 m change in altitude or from a 4° change in latitude or a climate change scenario corresponding to warming of 1.6–3.8°C. Thus, these differences introduced by the decoupling are significant from a climate change perspective, and the results demonstrate the need for incorporating microclimatic variation when conducting studies along altitudinal or latitudinal gradients. We emphasize the need for using relevant temperature data in climate impact studies and further call for more studies describing the soil surface microclimate, which is crucial for much of the biota.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2013-08-13},\n\tjournal = {Oikos},\n\tauthor = {Graae, Bente J. and De Frenne, Pieter and Kolb, Annette and Brunet, Jörg and Chabrerie, Olivier and Verheyen, Kris and Pepin, Nick and Heinken, Thilo and Zobel, Martin and Shevtsova, Anna and Nijs, Ivan and Milbau, Ann},\n\tyear = {2012},\n\tkeywords = {\\#nosource},\n\tpages = {3--19},\n}\n\n\n\n\n\n Global warming has created a need for studies along climatic gradients to assess the effects of temperature on ecological processes. Altitudinal and latitudinal gradients are often used as such, usually in combination with air temperature data from the closest weather station recorded at 1.5–2 m above the ground. However, many ecological processes occur in, at, or right above the soil surface. To evaluate how representative the commonly used weather station data are for the microclimate relevant for soil surface biota, we compared weather station temperatures for an altitudinal (500–900 m a.s.l.) and a latitudinal gradient (49–68°N) with data obtained by temperature sensors placed right below the soil surface at five sites along these gradients. The mean annual temperatures obtained from weather stations and adjusted using a lapse rate of −5.5°C km−1 were between 3.8°C lower and 1.6°C higher than those recorded by the temperature sensors at the soil surface, depending on the position along the gradients. The monthly mean temperatures were up to 10°C warmer or 5°C colder at the soil surface. The within-site variation in accumulated temperature was as high as would be expected from a 300 m change in altitude or from a 4° change in latitude or a climate change scenario corresponding to warming of 1.6–3.8°C. Thus, these differences introduced by the decoupling are significant from a climate change perspective, and the results demonstrate the need for incorporating microclimatic variation when conducting studies along altitudinal or latitudinal gradients. We emphasize the need for using relevant temperature data in climate impact studies and further call for more studies describing the soil surface microclimate, which is crucial for much of the biota.\n
\n\n\n\n \n\n \n \n \n \n \n Future Distribution of Arctic Char Salvelinus alpinus in Sweden under Climate Change: Effects of Temperature, Lake Size and Species Interactions.\n \n \n \n\n\n \n Hein, C. L.; Ohlund, G.; and Englund, G.\n\n\n \n\n\n\n Ambio, 41: 303–312. July 2012.\n \n\n\n\n
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\n\n\n@article{hein_future_2012,\n\ttitle = {Future {Distribution} of {Arctic} {Char} {Salvelinus} alpinus in {Sweden} under {Climate} {Change}: {Effects} of {Temperature}, {Lake} {Size} and {Species} {Interactions}},\n\tvolume = {41},\n\tissn = {0044-7447},\n\tshorttitle = {Future {Distribution} of {Arctic} {Char} {Salvelinus} alpinus in {Sweden} under {Climate} {Change}},\n\tdoi = {10.1007/s13280-012-0308-z},\n\tabstract = {Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95 \\% of 467 Swedish lakes. We predicted that Arctic char will lose 73 \\% of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.},\n\tlanguage = {English},\n\tjournal = {Ambio},\n\tauthor = {Hein, Catherine L. and Ohlund, Gunnar and Englund, Goran},\n\tmonth = jul,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Dispersal, Freshwater fish, Impacts, Species interactions, associations, biotic interactions, climate change, fish communities, fragmentation, fresh-water, prediction, salar, simulations, species distribution models, trout salmo-trutta},\n\tpages = {303--312},\n}\n\n\n\n\n\n Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95 % of 467 Swedish lakes. We predicted that Arctic char will lose 73 % of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.\n
\n\n\n\n \n\n \n \n \n \n \n Effects of Warming on Shrub Abundance and Chemistry Drive Ecosystem-Level Changes in a Forest-Tundra Ecotone.\n \n \n \n\n\n \n Kaarlejarvi, E.; Baxter, R.; Hofgaard, A.; Hytteborn, H.; Khitun, O.; Molau, U.; Sjoegersten, S.; Wookey, P.; and Olofsson, J.\n\n\n \n\n\n\n Ecosystems, 15(8): 1219–1233. December 2012.\n \n\n\n\n
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\n\n\n@article{kaarlejarvi_effects_2012,\n\ttitle = {Effects of {Warming} on {Shrub} {Abundance} and {Chemistry} {Drive} {Ecosystem}-{Level} {Changes} in a {Forest}-{Tundra} {Ecotone}},\n\tvolume = {15},\n\tissn = {1432-9840},\n\tdoi = {10.1007/s10021-012-9580-9},\n\tabstract = {Tundra vegetation is responding rapidly to on-going climate warming. The changes in plant abundance and chemistry might have cascading effects on tundra food webs, but an integrated understanding of how the responses vary between habitats and across environmental gradients is lacking. We assessed responses in plant abundance and plant chemistry to warmer climate, both at species and community levels, in two different habitats. We used a long-term and multisite warming (OTC) experiment in the Scandinavian forest-tundra ecotone to investigate (i) changes in plant community composition and (ii) responses in foliar nitrogen, phosphorus, and carbon-based secondary compound concentrations in two dominant evergreen dwarf-shrubs (Empetrum hermaphroditum and Vaccinium vitis-idaea) and two deciduous shrubs (Vaccinium myrtillus and Betula nana). We found that initial plant community composition, and the functional traits of these plants, will determine the responsiveness of the community composition, and thus community traits, to experimental warming. Although changes in plant chemistry within species were minor, alterations in plant community composition drive changes in community-level nutrient concentrations. In view of projected climate change, our results suggest that plant abundance will increase in the future, but nutrient concentrations in the tundra field layer vegetation will decrease. These effects are large enough to have knock-on consequences for major ecosystem processes like herbivory and nutrient cycling. The reduced food quality could lead to weaker trophic cascades and weaker top down control of plant community biomass and composition in the future. However, the opposite effects in forest indicate that these changes might be obscured by advancing treeline forests.},\n\tlanguage = {English},\n\tnumber = {8},\n\tjournal = {Ecosystems},\n\tauthor = {Kaarlejarvi, Elina and Baxter, Robert and Hofgaard, Annika and Hytteborn, Hakan and Khitun, Olga and Molau, Ulf and Sjoegersten, Sofie and Wookey, Philip and Olofsson, Johan},\n\tmonth = dec,\n\tyear = {2012},\n\tkeywords = {\\#nosource, arctic tundra, betula-nana, cbsc, climate-change, community responses, environment, global warming, grazing, n, northern alaska, p, phosphorus, plant secondary metabolites, reindeer, secondary plant metabolite, shrub, treeline, vegetation, winter},\n\tpages = {1219--1233},\n}\n\n\n\n\n\n Tundra vegetation is responding rapidly to on-going climate warming. The changes in plant abundance and chemistry might have cascading effects on tundra food webs, but an integrated understanding of how the responses vary between habitats and across environmental gradients is lacking. We assessed responses in plant abundance and plant chemistry to warmer climate, both at species and community levels, in two different habitats. We used a long-term and multisite warming (OTC) experiment in the Scandinavian forest-tundra ecotone to investigate (i) changes in plant community composition and (ii) responses in foliar nitrogen, phosphorus, and carbon-based secondary compound concentrations in two dominant evergreen dwarf-shrubs (Empetrum hermaphroditum and Vaccinium vitis-idaea) and two deciduous shrubs (Vaccinium myrtillus and Betula nana). We found that initial plant community composition, and the functional traits of these plants, will determine the responsiveness of the community composition, and thus community traits, to experimental warming. Although changes in plant chemistry within species were minor, alterations in plant community composition drive changes in community-level nutrient concentrations. In view of projected climate change, our results suggest that plant abundance will increase in the future, but nutrient concentrations in the tundra field layer vegetation will decrease. These effects are large enough to have knock-on consequences for major ecosystem processes like herbivory and nutrient cycling. The reduced food quality could lead to weaker trophic cascades and weaker top down control of plant community biomass and composition in the future. However, the opposite effects in forest indicate that these changes might be obscured by advancing treeline forests.\n
\n\n\n\n \n\n \n \n \n \n \n Changes in organic phosphorus composition in boreal forest humus soils: the role of iron and aluminium.\n \n \n \n\n\n \n Vincent, A. G.; Schleucher, J.; Grobner, G.; Vestergren, J.; Persson, P.; Jansson, M.; and Giesler, R.\n\n\n \n\n\n\n Biogeochemistry, 108(1-3): 485–499. April 2012.\n \n\n\n\n
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\n\n\n@article{vincent_changes_2012,\n\ttitle = {Changes in organic phosphorus composition in boreal forest humus soils: the role of iron and aluminium},\n\tvolume = {108},\n\tissn = {0168-2563},\n\tshorttitle = {Changes in organic phosphorus composition in boreal forest humus soils},\n\tdoi = {10.1007/s10533-011-9612-0},\n\tabstract = {Organic phosphorus (P) is an important component of boreal forest humus soils, and its concentration has been found to be closely related to the concentration of iron (Fe) and aluminium (Al). We used solution and solid state P-31 NMR spectroscopy on humus soils to characterize organic P along two groundwater recharge and discharge gradients in Fennoscandian boreal forest, which are also P sorption gradients due to differences in aluminium (Al) and iron (Fe) concentration in the humus. The composition of organic P changed sharply along the gradients. Phosphate diesters and their degradation products, as well as polyphosphates, were proportionally more abundant in low Al and Fe sites, whereas phosphate monoesters such as myo-, scyllo- and unknown inositol phosphates dominated in high Al and Fe soils. The concentration of inositol phosphates, but not that of diesters, was positively related to Al and Fe concentration in the humus soil. Overall, in high Al and Fe sites the composition of organic P seemed to be closely associated with stabilization processes, whereas in low Al and Fe sites it more closely reflected inputs of organic P, given the dominance of diesters which are generally assumed to constitute the bulk of organic P inputs to the soil. These gradients encompass the broad variation in soil properties detected in the wider Fennoscandian boreal forest landscape, as such our findings provide insight into the factors controlling P biogeochemistry in the region but should be of relevance to boreal forests elsewhere.},\n\tlanguage = {English},\n\tnumber = {1-3},\n\tjournal = {Biogeochemistry},\n\tauthor = {Vincent, Andrea G. and Schleucher, Jurgen and Grobner, Gerhard and Vestergren, Johan and Persson, Per and Jansson, Mats and Giesler, Reiner},\n\tmonth = apr,\n\tyear = {2012},\n\tkeywords = {\\#nosource, Betsele, Groundwater discharge, Groundwater recharge, Solid state P-31 NMR, Solution P-31 NMR spectroscopy, Sorption, accumulation, assignments, availability, extraction, identification, inositol phosphates, limitation, p-31 nmr-spectroscopy, phytate, retention},\n\tpages = {485--499},\n}\n\n\n\n\n\n Organic phosphorus (P) is an important component of boreal forest humus soils, and its concentration has been found to be closely related to the concentration of iron (Fe) and aluminium (Al). We used solution and solid state P-31 NMR spectroscopy on humus soils to characterize organic P along two groundwater recharge and discharge gradients in Fennoscandian boreal forest, which are also P sorption gradients due to differences in aluminium (Al) and iron (Fe) concentration in the humus. The composition of organic P changed sharply along the gradients. Phosphate diesters and their degradation products, as well as polyphosphates, were proportionally more abundant in low Al and Fe sites, whereas phosphate monoesters such as myo-, scyllo- and unknown inositol phosphates dominated in high Al and Fe soils. The concentration of inositol phosphates, but not that of diesters, was positively related to Al and Fe concentration in the humus soil. Overall, in high Al and Fe sites the composition of organic P seemed to be closely associated with stabilization processes, whereas in low Al and Fe sites it more closely reflected inputs of organic P, given the dominance of diesters which are generally assumed to constitute the bulk of organic P inputs to the soil. These gradients encompass the broad variation in soil properties detected in the wider Fennoscandian boreal forest landscape, as such our findings provide insight into the factors controlling P biogeochemistry in the region but should be of relevance to boreal forests elsewhere.\n
\n\n\n\n \n\n \n \n \n \n \n \n Chemical properties of plant litter in response to elevation: subarctic vegetation challenges phenolic allocation theories.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Wardle, D. A.; Olofsson, E.; Giesler, R.; and Gundale, M. J.\n\n\n \n\n\n\n Functional Ecology, 26(5): 1090–1099. October 2012.\n 00029\n\n\n\n
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\n\n\n@article{sundqvist_chemical_2012,\n\ttitle = {Chemical properties of plant litter in response to elevation: subarctic vegetation challenges phenolic allocation theories},\n\tvolume = {26},\n\tissn = {1365-2435},\n\tshorttitle = {Chemical properties of plant litter in response to elevation},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2012.02034.x/abstract},\n\tdoi = {10.1111/j.1365-2435.2012.02034.x},\n\tabstract = {* Several theories predict that increasing stress (e.g. decreasing nutrient availability or decreasing temperature) should result in higher amounts of plant phenolic compounds both at the interspecific and intraspecific levels. Further, several theories predict that plant phenolics are major drivers of plant–soil feedbacks whereby they influence litter decomposition rates and the return of nutrients to plants.\n\n\n* We investigated the potential influence of shifts in abiotic factors on litter phenolic properties using an elevational gradient in northern Sweden, for which temperature and soil fertility decline with increasing elevation. The system consists of two vegetation types: heath, (associated with low soil fertility) and meadow (associated with higher fertility), which occur across the entire gradient.\n\n\n* We hypothesized that total phenolics, tannins and protein complexation capacity (PCC) of leaf litter would increase with elevation within and among plant species. We further hypothesized that at the whole-plot level (using community-weighted averages), these properties would be higher in heath than meadow, and that phenolic properties for meadow vegetation would show stronger responses to elevation than for heath.\n\n\n* We measured phenolic properties in leaf litter for 13 species from both vegetation types across an established elevational gradient (500–1000 m) in Swedish subarctic tundra.\n\n\n* Contrary to our hypotheses, different species showed highly contrasting responses in their phenolic characteristics to elevation. At the across-species level, total phenolic content in litter decreased with elevation. At the whole-plot level, tannin concentrations were higher for the heath than for the meadow, whereas total phenolics and PCC did not differ. However, consistent with our hypothesis, our results showed that phenolic properties were more responsive to elevation for the meadow compared to the heath, as a consequence of greater species turnover for the meadow.\n\n\n* Our results are inconsistent with theories predicting higher plant phenolic concentrations with increasing environmental stress or decreasing nutrient availability. They also provide evidence that across abiotic gradients in the subarctic tundra, there are large shifts in litter phenolic properties (including those that are able to complex protein) and highlight that the direction and strength of such shifts may differ greatly among vegetation types.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-07},\n\tjournal = {Functional Ecology},\n\tauthor = {Sundqvist, Maja K. and Wardle, David A. and Olofsson, Elin and Giesler, Reiner and Gundale, Michael J.},\n\tmonth = oct,\n\tyear = {2012},\n\tnote = {00029},\n\tkeywords = {\\#nosource, Decomposition, carbon nutrient balance hypothesis, condensed tannins, litter chemistry, litter feedback, plant defence theory, protein complexation capacity, tundra},\n\tpages = {1090--1099},\n}\n\n\n\n\n\n * Several theories predict that increasing stress (e.g. decreasing nutrient availability or decreasing temperature) should result in higher amounts of plant phenolic compounds both at the interspecific and intraspecific levels. Further, several theories predict that plant phenolics are major drivers of plant–soil feedbacks whereby they influence litter decomposition rates and the return of nutrients to plants. * We investigated the potential influence of shifts in abiotic factors on litter phenolic properties using an elevational gradient in northern Sweden, for which temperature and soil fertility decline with increasing elevation. The system consists of two vegetation types: heath, (associated with low soil fertility) and meadow (associated with higher fertility), which occur across the entire gradient. * We hypothesized that total phenolics, tannins and protein complexation capacity (PCC) of leaf litter would increase with elevation within and among plant species. We further hypothesized that at the whole-plot level (using community-weighted averages), these properties would be higher in heath than meadow, and that phenolic properties for meadow vegetation would show stronger responses to elevation than for heath. * We measured phenolic properties in leaf litter for 13 species from both vegetation types across an established elevational gradient (500–1000 m) in Swedish subarctic tundra. * Contrary to our hypotheses, different species showed highly contrasting responses in their phenolic characteristics to elevation. At the across-species level, total phenolic content in litter decreased with elevation. At the whole-plot level, tannin concentrations were higher for the heath than for the meadow, whereas total phenolics and PCC did not differ. However, consistent with our hypothesis, our results showed that phenolic properties were more responsive to elevation for the meadow compared to the heath, as a consequence of greater species turnover for the meadow. * Our results are inconsistent with theories predicting higher plant phenolic concentrations with increasing environmental stress or decreasing nutrient availability. They also provide evidence that across abiotic gradients in the subarctic tundra, there are large shifts in litter phenolic properties (including those that are able to complex protein) and highlight that the direction and strength of such shifts may differ greatly among vegetation types.\n
\n\n\n\n \n\n \n \n \n \n \n \n Vole and lemming activity observed from space.\n \n \n \n \n\n\n \n Olofsson, J.; Tømmervik, H.; and Callaghan, T. V.\n\n\n \n\n\n\n Nature Climate Change, 2(12): 880–883. December 2012.\n 00058\n\n\n\n
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\n\n\n@article{olofsson_vole_2012,\n\ttitle = {Vole and lemming activity observed from space},\n\tvolume = {2},\n\tcopyright = {© 2012 Nature Publishing Group},\n\tissn = {1758-678X},\n\turl = {http://www.nature.com/nclimate/journal/v2/n12/full/nclimate1537.html},\n\tdoi = {10.1038/nclimate1537},\n\tabstract = {Predicting the impacts of present global warming requires an understanding of the factors controlling plant biomass and production. The extent to which they are controlled by bottom-up drivers such as climate, nutrient and water availability, and by top-down drivers such as herbivory and diseases in terrestrial systems is still under debate. By annually recording plant biomass and community composition in grazed control plots and in herbivore-free exclosures, at 12 sites in a subArctic ecosystem, we were able to show that the regular interannual density fluctuations of voles and lemmings drive synchronous interannual fluctuations in the biomass of field-layer vegetation. Plant biomass in the field layer was between 12 and 24\\% lower the year after a vole peak than the year before, and the combined vole and lemming peaks are visible as a reduced normalized difference vegetation index in satellite images over a 770 km2 area in the following year, despite the wide range of abiotic, biotic and anthropogenic forces that influence the vegetation. This strongly suggests that the cascading effect of rodents for the function and diversity of tundra plant communities needs to be included in our scenarios of how these ecosystems will respond to environmental changes.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2017-02-07},\n\tjournal = {Nature Climate Change},\n\tauthor = {Olofsson, Johan and Tømmervik, Hans and Callaghan, Terry V.},\n\tmonth = dec,\n\tyear = {2012},\n\tnote = {00058},\n\tkeywords = {\\#nosource, Climate-change ecology},\n\tpages = {880--883},\n}\n\n\n\n\n\n Predicting the impacts of present global warming requires an understanding of the factors controlling plant biomass and production. The extent to which they are controlled by bottom-up drivers such as climate, nutrient and water availability, and by top-down drivers such as herbivory and diseases in terrestrial systems is still under debate. By annually recording plant biomass and community composition in grazed control plots and in herbivore-free exclosures, at 12 sites in a subArctic ecosystem, we were able to show that the regular interannual density fluctuations of voles and lemmings drive synchronous interannual fluctuations in the biomass of field-layer vegetation. Plant biomass in the field layer was between 12 and 24% lower the year after a vole peak than the year before, and the combined vole and lemming peaks are visible as a reduced normalized difference vegetation index in satellite images over a 770 km2 area in the following year, despite the wide range of abiotic, biotic and anthropogenic forces that influence the vegetation. This strongly suggests that the cascading effect of rodents for the function and diversity of tundra plant communities needs to be included in our scenarios of how these ecosystems will respond to environmental changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Constrained microbial processing of allochthonous organic carbon in boreal lake sediments.\n \n \n \n \n\n\n \n Gudasz, C.; Bastviken, D.; Premke, K.; Steger, K.; and Tranvik, L. J.\n\n\n \n\n\n\n Limnology and Oceanography, 57(1): 163–175. 2012.\n _eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2012.57.1.0163\n\n\n\n
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\n\n\n@article{gudasz_constrained_2012,\n\ttitle = {Constrained microbial processing of allochthonous organic carbon in boreal lake sediments},\n\tvolume = {57},\n\tcopyright = {© 2012, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tissn = {1939-5590},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2012.57.1.0163},\n\tdoi = {10.4319/lo.2012.57.1.0163},\n\tabstract = {We investigated sediment bacterial metabolism in eight lakes with different inputs of allochthonous and autochthonous organic carbon in south-central Sweden. Sediment bacterial production, mineralization, and biomass were measured seasonally and along a lake depth gradient in lakes with different water and sediment characteristics. Sediment bacterial metabolism was primarily controlled by temperature but also by the quality and origin of organic carbon. Metabolism was positively correlated to measures of autochthonous influence on the sediment organic carbon, but did not show a similar increase with increasing input of allochthonous organic carbon. Hence, in contrast to what is currently known for the water column, increasing terrestrial organic carbon influence does not result in enhanced sediment bacterial metabolism. The role of allochthonous organic carbon as the main driver of sediment bacterial metabolism suggested so far is contrary to our findings. Meio- and macrobenthic invertebrate biomass were, at most, weakly correlated to bacterial metabolism and biomass, suggesting limited control of sediment bacteria by grazing. Bacterial metabolism in boreal lake sediments is constrained by low temperatures and by the recalcitrant nature of the dominant organic carbon, resulting in sediments being an effective sink of organic carbon.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-08-31},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Gudasz, Cristian and Bastviken, David and Premke, Katrin and Steger, Kristin and Tranvik, Lars J.},\n\tyear = {2012},\n\tnote = {\\_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2012.57.1.0163},\n\tkeywords = {\\#nosource},\n\tpages = {163--175},\n}\n\n\n\n\n\n We investigated sediment bacterial metabolism in eight lakes with different inputs of allochthonous and autochthonous organic carbon in south-central Sweden. Sediment bacterial production, mineralization, and biomass were measured seasonally and along a lake depth gradient in lakes with different water and sediment characteristics. Sediment bacterial metabolism was primarily controlled by temperature but also by the quality and origin of organic carbon. Metabolism was positively correlated to measures of autochthonous influence on the sediment organic carbon, but did not show a similar increase with increasing input of allochthonous organic carbon. Hence, in contrast to what is currently known for the water column, increasing terrestrial organic carbon influence does not result in enhanced sediment bacterial metabolism. The role of allochthonous organic carbon as the main driver of sediment bacterial metabolism suggested so far is contrary to our findings. Meio- and macrobenthic invertebrate biomass were, at most, weakly correlated to bacterial metabolism and biomass, suggesting limited control of sediment bacteria by grazing. Bacterial metabolism in boreal lake sediments is constrained by low temperatures and by the recalcitrant nature of the dominant organic carbon, resulting in sediments being an effective sink of organic carbon.\n
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\n \n \n\n \n \n \n \n \n \n Burrow extension with a proboscis: mechanics of burrowing by the glycerid Hemipodus simplex.\n \n \n \n \n\n\n \n Murphy, E. A. K.; and Dorgan, K. M.\n\n\n \n\n\n\n Journal of Experimental Biology, 214(6): 1017–1027. March 2011.\n \n\n\n\n
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\n\n\n@article{murphy_burrow_2011,\n\ttitle = {Burrow extension with a proboscis: mechanics of burrowing by the glycerid {Hemipodus} simplex},\n\tvolume = {214},\n\tcopyright = {© 2011.},\n\tissn = {0022-0949, 1477-9145},\n\tshorttitle = {Burrow extension with a proboscis},\n\turl = {https://jeb.biologists.org/content/214/6/1017},\n\tdoi = {10.1242/jeb.051227},\n\tabstract = {Skip to Next Section\nBurrowing marine infauna are morphologically diverse and ecologically important as ecosystem engineers. The polychaetes Nereis virens and Cirriformia moorei extend their burrows by crack propagation. Nereis virens does so by everting its pharynx and C. moorei, lacking an eversible pharynx or proboscis, uses its hydrostatic skeleton to expand its anterior. Both behaviors apply stress to the burrow wall that is amplified at the tip of the crack, which extends by fracture. That two species with such distinct morphologies and life histories both burrow by fracturing sediment suggests that this mechanism may be widespread among burrowers. We tested this hypothesis with the glycerid polychaete Hemipodus simplex, which has an eversible proboscis that is much longer and everts more rapidly than the pharynx of N. virens. When the proboscis is fully everted, the tip flares out wider than the rest of the proboscis, creating a shape and applying a stress distribution similar to that of N. virens and resulting in relatively large forces near the tip of the crack. These forces are larger than necessary to extend the crack by fracture and are surprisingly uncorrelated with the resulting stress amplification at the crack tip, which is also larger than necessary to extend the burrow by fracture. These large forces may plastically deform the mud, allowing the worm to build a semi-permanent burrow. Our results illustrate that similar mechanisms of burrowing are used by morphologically different burrowers.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2019-07-16},\n\tjournal = {Journal of Experimental Biology},\n\tauthor = {Murphy, Elizabeth A. K. and Dorgan, Kelly M.},\n\tmonth = mar,\n\tyear = {2011},\n\tpmid = {21346130},\n\tkeywords = {\\#nosource},\n\tpages = {1017--1027},\n}\n\n\n\n\n\n Skip to Next Section Burrowing marine infauna are morphologically diverse and ecologically important as ecosystem engineers. The polychaetes Nereis virens and Cirriformia moorei extend their burrows by crack propagation. Nereis virens does so by everting its pharynx and C. moorei, lacking an eversible pharynx or proboscis, uses its hydrostatic skeleton to expand its anterior. Both behaviors apply stress to the burrow wall that is amplified at the tip of the crack, which extends by fracture. That two species with such distinct morphologies and life histories both burrow by fracturing sediment suggests that this mechanism may be widespread among burrowers. We tested this hypothesis with the glycerid polychaete Hemipodus simplex, which has an eversible proboscis that is much longer and everts more rapidly than the pharynx of N. virens. When the proboscis is fully everted, the tip flares out wider than the rest of the proboscis, creating a shape and applying a stress distribution similar to that of N. virens and resulting in relatively large forces near the tip of the crack. These forces are larger than necessary to extend the crack by fracture and are surprisingly uncorrelated with the resulting stress amplification at the crack tip, which is also larger than necessary to extend the burrow by fracture. These large forces may plastically deform the mud, allowing the worm to build a semi-permanent burrow. Our results illustrate that similar mechanisms of burrowing are used by morphologically different burrowers.\n
\n\n\n\n \n\n \n \n \n \n \n \n Paleoecological evidence of major declines in total organic carbon concentrations since the nineteenth century in four nemoboreal lakes.\n \n \n \n \n\n\n \n Cunningham, L.; Bishop, K.; Mettävainio, E.; and Rosén, P.\n\n\n \n\n\n\n Journal of Paleolimnology, 45(4): 507–518. April 2011.\n 00040\n\n\n\n
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\n\n\n@article{cunningham_paleoecological_2011,\n\ttitle = {Paleoecological evidence of major declines in total organic carbon concentrations since the nineteenth century in four nemoboreal lakes},\n\tvolume = {45},\n\tissn = {0921-2728, 1573-0417},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1007/s10933-010-9420-x},\n\tdoi = {10.1007/s10933-010-9420-x},\n\tabstract = {A decade of widespread increases in surface water concentrations of total organic carbon (TOC) in some regions has raised questions about longer term patterns in this important constituent of water chemistry. This study uses near-infrared spectroscopy (NIRS) to infer lake water TOC far beyond the decade or two of observational data generally available. An expanded calibration dataset of 140 lakes across Sweden covering a TOC gradient from 0.7 to 24.7 mg L−1 was used to establish a relationship between the NIRS signal from surface sediments (0–0.5 cm) and the TOC concentration of the water mass. Internal cross-validation of the model resulted in an R2 of 0.72 with a root mean squared error of calibration (RMSECV) of 2.6 mg L−1. The TOC concentrations reconstructed from surface sediments in four Swedish lakes were typically within the range of concentrations observed in the monitoring data during the period represented by each sediment layer. TOC reconstructions from the full sediment cores of four lakes indicated that TOC concentrations were approximately twice as high a century ago.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2016-11-09},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Cunningham, Laura and Bishop, Kevin and Mettävainio, Eva and Rosén, Peter},\n\tmonth = apr,\n\tyear = {2011},\n\tnote = {00040},\n\tkeywords = {\\#nosource},\n\tpages = {507--518},\n}\n\n\n\n\n\n A decade of widespread increases in surface water concentrations of total organic carbon (TOC) in some regions has raised questions about longer term patterns in this important constituent of water chemistry. This study uses near-infrared spectroscopy (NIRS) to infer lake water TOC far beyond the decade or two of observational data generally available. An expanded calibration dataset of 140 lakes across Sweden covering a TOC gradient from 0.7 to 24.7 mg L−1 was used to establish a relationship between the NIRS signal from surface sediments (0–0.5 cm) and the TOC concentration of the water mass. Internal cross-validation of the model resulted in an R2 of 0.72 with a root mean squared error of calibration (RMSECV) of 2.6 mg L−1. The TOC concentrations reconstructed from surface sediments in four Swedish lakes were typically within the range of concentrations observed in the monitoring data during the period represented by each sediment layer. TOC reconstructions from the full sediment cores of four lakes indicated that TOC concentrations were approximately twice as high a century ago.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dispersal through stream networks: modelling climate-driven range expansions of fishes.\n \n \n \n \n\n\n \n Hein, C. L.; Öhlund, G.; and Englund, G.\n\n\n \n\n\n\n Diversity and Distributions, 17(4): 641–651. July 2011.\n \n\n\n\n
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\n\n\n@article{hein_dispersal_2011,\n\ttitle = {Dispersal through stream networks: modelling climate-driven range expansions of fishes},\n\tvolume = {17},\n\tissn = {1472-4642},\n\tshorttitle = {Dispersal through stream networks},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4642.2011.00776.x/abstract},\n\tdoi = {10.1111/j.1472-4642.2011.00776.x},\n\tabstract = {Aim To incorporate dispersal through stream networks into models predicting the future distribution of a native, freshwater fish given climate change scenarios. Location Sweden. Methods We used logistic regression to fit climate and habitat data to observed pike (Esox lucius Linnaeus) distributions in 13,476 lakes. We used GIS to map dispersal pathways through streams. Lakes either (1) contained pike or were downstream from pike lakes, (2) were upstream from pike lakes, but downstream from natural dispersal barriers, or (3) were isolated from streams or were upstream from natural dispersal barriers. We then used climate projections to model future distributions of pike and compared our results with and without including dispersal. Results Given climate and habitat, pike were predicted present in all of 99,249 Swedish lakes by 2100. After accounting for dispersal barriers, we only predicted pike presence in 31,538 lakes. Dispersal barriers most strongly limited pike invasion in mountainous regions, but low connectivity also characterized some relatively flat regions. Main conclusions The dendritic network structure of streams and interconnected lakes makes a two-dimensional representation of the landscape unsuitable for predicting range shifts of many freshwater organisms. If dispersal through stream networks is not accounted for, predictions of future fish distributions in a warmer climate might grossly overestimate range expansions of warm and cool-water fishes and underestimate range contractions of cold-water fishes. Dispersal through stream networks can be modelled in any region for which a digital elevation model and species occurrence data are available.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-08},\n\tjournal = {Diversity and Distributions},\n\tauthor = {Hein, Catherine L. and Öhlund, Gunnar and Englund, Göran},\n\tmonth = jul,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Bioclimate envelope models, climate change, connectivity, dispersal barriers, fish distributions, stream networks},\n\tpages = {641--651},\n}\n\n\n\n\n\n Aim To incorporate dispersal through stream networks into models predicting the future distribution of a native, freshwater fish given climate change scenarios. Location Sweden. Methods We used logistic regression to fit climate and habitat data to observed pike (Esox lucius Linnaeus) distributions in 13,476 lakes. We used GIS to map dispersal pathways through streams. Lakes either (1) contained pike or were downstream from pike lakes, (2) were upstream from pike lakes, but downstream from natural dispersal barriers, or (3) were isolated from streams or were upstream from natural dispersal barriers. We then used climate projections to model future distributions of pike and compared our results with and without including dispersal. Results Given climate and habitat, pike were predicted present in all of 99,249 Swedish lakes by 2100. After accounting for dispersal barriers, we only predicted pike presence in 31,538 lakes. Dispersal barriers most strongly limited pike invasion in mountainous regions, but low connectivity also characterized some relatively flat regions. Main conclusions The dendritic network structure of streams and interconnected lakes makes a two-dimensional representation of the landscape unsuitable for predicting range shifts of many freshwater organisms. If dispersal through stream networks is not accounted for, predictions of future fish distributions in a warmer climate might grossly overestimate range expansions of warm and cool-water fishes and underestimate range contractions of cold-water fishes. Dispersal through stream networks can be modelled in any region for which a digital elevation model and species occurrence data are available.\n
\n\n\n\n \n\n \n \n \n \n \n \n Predicted changes in vegetation structure affect the susceptibility to invasion of bryophyte-dominated subarctic heath.\n \n \n \n \n\n\n \n Eckstein, R. L.; Eva Pereira; Milbau, A.; and Graae, B. J.\n\n\n \n\n\n\n Annals of Botany, 108(1): 177–183. July 2011.\n \n\n\n\n
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\n\n\n@article{eckstein_predicted_2011,\n\ttitle = {Predicted changes in vegetation structure affect the susceptibility to invasion of bryophyte-dominated subarctic heath},\n\tvolume = {108},\n\tissn = {0305-7364, 1095-8290},\n\turl = {http://aob.oxfordjournals.org.proxy.ub.umu.se/content/108/1/177},\n\tdoi = {10.1093/aob/mcr097},\n\tabstract = {Background and Aims A meta-analysis of global change experiments in arctic tundra sites suggests that plant productivity and the cover of shrubs, grasses and dead plant material (i.e. litter) will increase and the cover of bryophytes will decrease in response to higher air temperatures. However, little is known about which effects these changes in vegetation structure will have on seedling recruitment of species and invasibility of arctic ecosystems.\nMethods A field experiment was done in a bryophyte-dominated, species-rich subarctic heath by manipulating the cover of bryophytes and litter in a factorial design. Three phases of seedling recruitment (seedling emergence, summer seedling survival, first-year recruitment) of the grass Anthoxanthum alpinum and the shrub Betula nana were analysed after they were sown into the experimental plots.\nKey Results Bryophyte and litter removal significantly increased seedling emergence of both species but the effects of manipulations of vegetation structure varied strongly for the later phases of recruitment. Summer survival and first-year recruitment were significantly higher in Anthoxanthum. Although bryophyte removal generally increased summer survival and recruitment, seedlings of Betula showed high mortality in early August on plots where bryophytes had been removed.\nConclusions Large species-specific variation and significant effects of experimental manipulations on seedling recruitment suggest that changes in vegetation structure as a consequence of global warming will affect the abundance of grasses and shrubs, the species composition and the susceptibility to invasion of subarctic heath vegetation.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2016-11-08},\n\tjournal = {Annals of Botany},\n\tauthor = {Eckstein, R. Lutz and {Eva Pereira} and Milbau, Ann and Graae, Bente Jessen},\n\tmonth = jul,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Anthoxanthum alpinum, Betula nana, Bryophytes, deciduous shrubs, global warming, graminoids, invasibility, litter, recruitment, seedling emergence},\n\tpages = {177--183},\n}\n\n\n\n\n\n Background and Aims A meta-analysis of global change experiments in arctic tundra sites suggests that plant productivity and the cover of shrubs, grasses and dead plant material (i.e. litter) will increase and the cover of bryophytes will decrease in response to higher air temperatures. However, little is known about which effects these changes in vegetation structure will have on seedling recruitment of species and invasibility of arctic ecosystems. Methods A field experiment was done in a bryophyte-dominated, species-rich subarctic heath by manipulating the cover of bryophytes and litter in a factorial design. Three phases of seedling recruitment (seedling emergence, summer seedling survival, first-year recruitment) of the grass Anthoxanthum alpinum and the shrub Betula nana were analysed after they were sown into the experimental plots. Key Results Bryophyte and litter removal significantly increased seedling emergence of both species but the effects of manipulations of vegetation structure varied strongly for the later phases of recruitment. Summer survival and first-year recruitment were significantly higher in Anthoxanthum. Although bryophyte removal generally increased summer survival and recruitment, seedlings of Betula showed high mortality in early August on plots where bryophytes had been removed. Conclusions Large species-specific variation and significant effects of experimental manipulations on seedling recruitment suggest that changes in vegetation structure as a consequence of global warming will affect the abundance of grasses and shrubs, the species composition and the susceptibility to invasion of subarctic heath vegetation.\n
\n\n\n\n \n\n \n \n \n \n \n \n A Race for Space? How Sphagnum fuscum stabilizes vegetation composition during long-term climate manipulations.\n \n \n \n \n\n\n \n Keuper, F.; Dorrepaal, E.; Van Bodegom, P. M.; Aerts, R.; Van Logtestijn, R. S. P.; Callaghan, T. V.; and Cornelissen, J. H. C.\n\n\n \n\n\n\n Global Change Biology, 17(6): 2162–2171. June 2011.\n \n\n\n\n
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\n\n\n@article{keuper_race_2011,\n\ttitle = {A {Race} for {Space}? {How} {Sphagnum} fuscum stabilizes vegetation composition during long-term climate manipulations},\n\tvolume = {17},\n\tissn = {1365-2486},\n\tshorttitle = {A {Race} for {Space}?},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2010.02377.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2010.02377.x},\n\tabstract = {Strong climate warming is predicted at higher latitudes this century, with potentially major consequences for productivity and carbon sequestration. Although northern peatlands contain one-third of the world's soil organic carbon, little is known about the long-term responses to experimental climate change of vascular plant communities in these Sphagnum-dominated ecosystems. We aimed to see how long-term experimental climate manipulations, relevant to different predicted future climate scenarios, affect total vascular plant abundance and species composition when the community is dominated by mosses. During 8 years, we investigated how the vascular plant community of a Sphagnum fuscum-dominated subarctic peat bog responded to six experimental climate regimes, including factorial combinations of summer as well as spring warming and a thicker snow cover. Vascular plant species composition in our peat bog was more stable than is typically observed in (sub)arctic experiments: neither changes in total vascular plant abundance, nor in individual species abundances, Shannon's diversity or evenness were found in response to the climate manipulations. For three key species (Empetrum hermaphroditum, Betula nana and S. fuscum) we also measured whether the treatments had a sustained effect on plant length growth responses and how these responses interacted. Contrasting with the stability at the community level, both key shrubs and the peatmoss showed sustained positive growth responses at the plant level to the climate treatments. However, a higher percentage of moss-encroached E. hermaphroditum shoots and a lack of change in B. nana net shrub height indicated encroachment by S. fuscum, resulting in long-term stability of the vascular community composition: in a warmer world, vascular species of subarctic peat bogs appear to just keep pace with growing Sphagnum in their race for space. Our findings contribute to general ecological theory by demonstrating that community resistance to environmental changes does not necessarily mean inertia in vegetation response.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Keuper, Frida and Dorrepaal, Ellen and Van Bodegom, Peter M. and Aerts, Rien and Van Logtestijn, Richard S. P. and Callaghan, Terry V. and Cornelissen, Johannes H. C.},\n\tmonth = jun,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Bryophyte, climate change, diversity, long-term manipulation, peatland, resistance, snow addition, spring warming, summer warming, vascular vegetation composition},\n\tpages = {2162--2171},\n}\n\n\n\n\n\n Strong climate warming is predicted at higher latitudes this century, with potentially major consequences for productivity and carbon sequestration. Although northern peatlands contain one-third of the world's soil organic carbon, little is known about the long-term responses to experimental climate change of vascular plant communities in these Sphagnum-dominated ecosystems. We aimed to see how long-term experimental climate manipulations, relevant to different predicted future climate scenarios, affect total vascular plant abundance and species composition when the community is dominated by mosses. During 8 years, we investigated how the vascular plant community of a Sphagnum fuscum-dominated subarctic peat bog responded to six experimental climate regimes, including factorial combinations of summer as well as spring warming and a thicker snow cover. Vascular plant species composition in our peat bog was more stable than is typically observed in (sub)arctic experiments: neither changes in total vascular plant abundance, nor in individual species abundances, Shannon's diversity or evenness were found in response to the climate manipulations. For three key species (Empetrum hermaphroditum, Betula nana and S. fuscum) we also measured whether the treatments had a sustained effect on plant length growth responses and how these responses interacted. Contrasting with the stability at the community level, both key shrubs and the peatmoss showed sustained positive growth responses at the plant level to the climate treatments. However, a higher percentage of moss-encroached E. hermaphroditum shoots and a lack of change in B. nana net shrub height indicated encroachment by S. fuscum, resulting in long-term stability of the vascular community composition: in a warmer world, vascular species of subarctic peat bogs appear to just keep pace with growing Sphagnum in their race for space. Our findings contribute to general ecological theory by demonstrating that community resistance to environmental changes does not necessarily mean inertia in vegetation response.\n
\n\n\n\n \n\n \n \n \n \n \n \n Universally Applicable Model for the Quantitative Determination of Lake Sediment Composition Using Fourier Transform Infrared Spectroscopy.\n \n \n \n \n\n\n \n Rosén, P.; Vogel, H.; Cunningham, L.; Hahn, A.; Hausmann, S.; Pienitz, R.; Zolitschka, B.; Wagner, B.; and Persson, P.\n\n\n \n\n\n\n Environmental Science & Technology, 45(20): 8858–8865. October 2011.\n \n\n\n\n
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\n\n\n@article{rosen_universally_2011,\n\ttitle = {Universally {Applicable} {Model} for the {Quantitative} {Determination} of {Lake} {Sediment} {Composition} {Using} {Fourier} {Transform} {Infrared} {Spectroscopy}},\n\tvolume = {45},\n\tissn = {0013-936X},\n\turl = {http://dx.doi.org/10.1021/es200203z},\n\tdoi = {10.1021/es200203z},\n\tabstract = {Fourier transform infrared spectroscopy (FTIRS) can provide detailed information on organic and minerogenic constituents of sediment records. Based on a large number of sediment samples of varying age (0–340 000 yrs) and from very diverse lake settings in Antarctica, Argentina, Canada, Macedonia/Albania, Siberia, and Sweden, we have developed universally applicable calibration models for the quantitative determination of biogenic silica (BSi; n = 816), total inorganic carbon (TIC; n = 879), and total organic carbon (TOC; n = 3164) using FTIRS. These models are based on the differential absorbance of infrared radiation at specific wavelengths with varying concentrations of individual parameters, due to molecular vibrations associated with each parameter. The calibration models have low prediction errors and the predicted values are highly correlated with conventionally measured values (R = 0.94–0.99). Robustness tests indicate the accuracy of the newly developed FTIRS calibration models is similar to that of conventional geochemical analyses. Consequently FTIRS offers a useful and rapid alternative to conventional analyses for the quantitative determination of BSi, TIC, and TOC. The rapidity, cost-effectiveness, and small sample size required enables FTIRS determination of geochemical properties to be undertaken at higher resolutions than would otherwise be possible with the same resource allocation, thus providing crucial sedimentological information for climatic and environmental reconstructions.},\n\tnumber = {20},\n\turldate = {2016-11-09},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Rosén, Peter and Vogel, Hendrik and Cunningham, Laura and Hahn, Annette and Hausmann, Sonja and Pienitz, Reinhard and Zolitschka, Bernd and Wagner, Bernd and Persson, Per},\n\tmonth = oct,\n\tyear = {2011},\n\tkeywords = {\\#nosource},\n\tpages = {8858--8865},\n}\n\n\n\n\n\n Fourier transform infrared spectroscopy (FTIRS) can provide detailed information on organic and minerogenic constituents of sediment records. Based on a large number of sediment samples of varying age (0–340 000 yrs) and from very diverse lake settings in Antarctica, Argentina, Canada, Macedonia/Albania, Siberia, and Sweden, we have developed universally applicable calibration models for the quantitative determination of biogenic silica (BSi; n = 816), total inorganic carbon (TIC; n = 879), and total organic carbon (TOC; n = 3164) using FTIRS. These models are based on the differential absorbance of infrared radiation at specific wavelengths with varying concentrations of individual parameters, due to molecular vibrations associated with each parameter. The calibration models have low prediction errors and the predicted values are highly correlated with conventionally measured values (R = 0.94–0.99). Robustness tests indicate the accuracy of the newly developed FTIRS calibration models is similar to that of conventional geochemical analyses. Consequently FTIRS offers a useful and rapid alternative to conventional analyses for the quantitative determination of BSi, TIC, and TOC. The rapidity, cost-effectiveness, and small sample size required enables FTIRS determination of geochemical properties to be undertaken at higher resolutions than would otherwise be possible with the same resource allocation, thus providing crucial sedimentological information for climatic and environmental reconstructions.\n
\n\n\n\n \n\n \n \n \n \n \n \n An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient.\n \n \n \n \n\n\n \n De Frenne, P.; Graae, B. J.; Kolb, A.; Shevtsova, A.; Baeten, L.; Brunet, J.; Chabrerie, O.; Cousins, S. A. O.; Decocq, G.; Dhondt, R.; Diekmann, M.; Gruwez, R.; Heinken, T.; Hermy, M.; Öster, M.; Saguez, R.; Stanton, S.; Tack, W.; Vanhellemont, M.; and Verheyen, K.\n\n\n \n\n\n\n Ecography, 34(1): 132–140. February 2011.\n 00034\n\n\n\n
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\n\n\n@article{de_frenne_intraspecific_2011,\n\ttitle = {An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient},\n\tvolume = {34},\n\tcopyright = {© 2011 The Authors},\n\tissn = {1600-0587},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0587.2010.06399.x},\n\tdoi = {10.1111/j.1600-0587.2010.06399.x},\n\tabstract = {We applied the leaf-height-seed (LHS) ecology strategy scheme (a combination of three ecologically important traits: specific leaf area (SLA), seed mass and plant height) intraspecifically to two widespread European forest herbs along a latitudinal gradient. The aims of this study were to quantify LHS trait variation, disentangle the environmental factors affecting these traits and compare the within-species LHS trait relationships with latitude to previously established cross-species comparisons. We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900–2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4\\% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-06-14},\n\tjournal = {Ecography},\n\tauthor = {De Frenne, Pieter and Graae, Bente J. and Kolb, Annette and Shevtsova, Anna and Baeten, Lander and Brunet, Jörg and Chabrerie, Olivier and Cousins, Sara A. O. and Decocq, Guillaume and Dhondt, Rob and Diekmann, Martin and Gruwez, Robert and Heinken, Thilo and Hermy, Martin and Öster, Mathias and Saguez, Robert and Stanton, Sharon and Tack, Wesley and Vanhellemont, Margot and Verheyen, Kris},\n\tmonth = feb,\n\tyear = {2011},\n\tnote = {00034},\n\tkeywords = {\\#nosource},\n\tpages = {132--140},\n}\n\n\n\n\n\n We applied the leaf-height-seed (LHS) ecology strategy scheme (a combination of three ecologically important traits: specific leaf area (SLA), seed mass and plant height) intraspecifically to two widespread European forest herbs along a latitudinal gradient. The aims of this study were to quantify LHS trait variation, disentangle the environmental factors affecting these traits and compare the within-species LHS trait relationships with latitude to previously established cross-species comparisons. We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900–2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.\n
\n\n\n\n \n\n \n \n \n \n \n \n Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient.\n \n \n \n \n\n\n \n De Frenne, P.; Brunet, J.; Shevtsova, A.; Kolb, A.; Graae, B. J.; Chabrerie, O.; Cousins, S. A.; Decocq, G.; Schrijver, A. D.; Diekmann, M.; Gruwez, R.; Heinken, T.; Hermy, M.; Nilsson, C.; Stanton, S.; Tack, W.; Willaert, J.; and Verheyen, K.\n\n\n \n\n\n\n Global Change Biology, 17(10): 3240–3253. April 2011.\n 00081\n\n\n\n
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\n\n\n@article{de_frenne_temperature_2011,\n\ttitle = {Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient},\n\tvolume = {17},\n\tcopyright = {© 2011 Blackwell Publishing Ltd},\n\tissn = {1365-2486},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2011.02449.x},\n\tdoi = {10.1111/j.1365-2486.2011.02449.x},\n\tabstract = {Slow-colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large-scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short- and long-term persistence. We combined transplant experiments along a latitudinal gradient with open-top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow-colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e.g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open-top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2018-06-14},\n\tjournal = {Global Change Biology},\n\tauthor = {De Frenne, Pieter and Brunet, Jörg and Shevtsova, Anna and Kolb, Annette and Graae, Bente J. and Chabrerie, Olivier and Cousins, Sara Ao and Decocq, Guillaume and Schrijver, AN De and Diekmann, Martin and Gruwez, Robert and Heinken, Thilo and Hermy, Martin and Nilsson, Christer and Stanton, Sharon and Tack, Wesley and Willaert, Justin and Verheyen, Kris},\n\tmonth = apr,\n\tyear = {2011},\n\tnote = {00081},\n\tkeywords = {\\#nosource, climate change, common garden experiment, forest understorey, latitude, local adaptation, open-top chambers, phenotypic plasticity, pot experiment},\n\tpages = {3240--3253},\n}\n\n\n\n\n\n Slow-colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large-scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short- and long-term persistence. We combined transplant experiments along a latitudinal gradient with open-top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow-colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e.g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open-top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon balance of Arctic tundra under increased snow cover mediated by a plant pathogen.\n \n \n \n \n\n\n \n Olofsson, J.; Ericson, L.; Torp, M.; Stark, S.; and Baxter, R.\n\n\n \n\n\n\n Nature Climate Change, 1(4): 220–223. July 2011.\n 00047\n\n\n\n
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\n\n\n@article{olofsson_carbon_2011,\n\ttitle = {Carbon balance of {Arctic} tundra under increased snow cover mediated by a plant pathogen},\n\tvolume = {1},\n\tcopyright = {© 2011 Nature Publishing Group},\n\tissn = {1758-678X},\n\turl = {http://www.nature.com/nclimate/journal/v1/n4/abs/nclimate1142.html},\n\tdoi = {10.1038/nclimate1142},\n\tabstract = {Climate change is affecting plant community composition and ecosystem structure, with consequences for ecosystem processes such as carbon storage. Climate can affect plants directly by altering growth rates, and indirectly by affecting predators and herbivores, which in turn influence plants. Diseases are also known to be important for the structure and function of food webs. However, the role of plant diseases in modulating ecosystem responses to a changing climate is poorly understood. This is partly because disease outbreaks are relatively rare and spatially variable, such that that their effects can only be captured in long-term experiments. Here we show that, although plant growth was favoured by the insulating effects of increased snow cover in experimental plots in Sweden, plant biomass decreased over the seven-year study. The decline in biomass was caused by an outbreak of a host-specific parasitic fungus, Arwidssonia empetri, which killed the majority of the shoots of the dominant plant species, Empetrum hermaphroditum, after six years of increased snow cover. After the outbreak of the disease, instantaneous measurements of gross photosynthesis and net ecosystem carbon exchange were significantly reduced at midday during the growing season. Our results show that plant diseases can alter and even reverse the effects of a changing climate on tundra carbon balance by altering plant composition.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-07},\n\tjournal = {Nature Climate Change},\n\tauthor = {Olofsson, Johan and Ericson, Lars and Torp, Mikaela and Stark, Sari and Baxter, Robert},\n\tmonth = jul,\n\tyear = {2011},\n\tnote = {00047},\n\tkeywords = {\\#nosource, Pathogens, Plant ecology, climate change},\n\tpages = {220--223},\n}\n\n\n\n\n\n Climate change is affecting plant community composition and ecosystem structure, with consequences for ecosystem processes such as carbon storage. Climate can affect plants directly by altering growth rates, and indirectly by affecting predators and herbivores, which in turn influence plants. Diseases are also known to be important for the structure and function of food webs. However, the role of plant diseases in modulating ecosystem responses to a changing climate is poorly understood. This is partly because disease outbreaks are relatively rare and spatially variable, such that that their effects can only be captured in long-term experiments. Here we show that, although plant growth was favoured by the insulating effects of increased snow cover in experimental plots in Sweden, plant biomass decreased over the seven-year study. The decline in biomass was caused by an outbreak of a host-specific parasitic fungus, Arwidssonia empetri, which killed the majority of the shoots of the dominant plant species, Empetrum hermaphroditum, after six years of increased snow cover. After the outbreak of the disease, instantaneous measurements of gross photosynthesis and net ecosystem carbon exchange were significantly reduced at midday during the growing season. Our results show that plant diseases can alter and even reverse the effects of a changing climate on tundra carbon balance by altering plant composition.\n
\n\n\n\n \n\n \n \n \n \n \n \n The origin of lead in the organic horizon of tundra soils: Atmospheric deposition, plant translocation from the mineral soil or soil mineral mixing?.\n \n \n \n \n\n\n \n Klaminder, J.; Farmer, J. G.; and MacKenzie, A. B.\n\n\n \n\n\n\n Science of The Total Environment, 409(20): 4344–4350. September 2011.\n \n\n\n\n
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\n\n\n@article{klaminder_origin_2011,\n\ttitle = {The origin of lead in the organic horizon of tundra soils: {Atmospheric} deposition, plant translocation from the mineral soil or soil mineral mixing?},\n\tvolume = {409},\n\tissn = {0048-9697},\n\tshorttitle = {The origin of lead in the organic horizon of tundra soils},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969711007212},\n\tdoi = {10.1016/j.scitotenv.2011.07.005},\n\tabstract = {Knowledge of the anthropogenic contribution to lead (Pb) concentrations in surface soils in high latitude ecosystems is central to our understanding of the extent of atmospheric Pb contamination. In this study, we reconstructed fallout of Pb at a remote sub-arctic region by using two ombrotrophic peat cores and assessed the extent to which this airborne Pb is able to explain the isotopic composition (206Pb/207Pb ratio) in the O-horizon of tundra soils. In the peat cores, long-range atmospheric fallout appeared to be the main source of Pb as indicated by temporal trends that followed the known European pollution history, i.e. accelerated fallout at the onset of industrialization and peak fallout around the 1960s–70s. The Pb isotopic composition of the O-horizon of podzolic tundra soil (206Pb/207Pb = 1.170 ± 0.002; mean ± SD) overlapped with that of the peat (206Pb/207Pb = 1.16 ± 0.01) representing a proxy for atmospheric aerosols, but was clearly different from that of the parent soil material (206Pb/207Pb = 1.22–1.30). This finding indicated that long-range fallout of atmospheric Pb is the main driver of Pb accumulation in podzolic tundra soil. In O-horizons of tundra soil weakly affected by cryoturbation (cryosols) however, the input of Pb from the underlying mineral soil increased as indicated by 206Pb/207Pb ratios of up to 1.20, a value closer to that of local soil minerals. Nevertheless, atmospheric Pb appeared to be the dominant source in this soil compartment. We conclude that Pb concentrations in the O-horizon of studied tundra soils – despite being much lower than in boreal soils and representative for one of the least exposed sites to atmospheric Pb contaminants in Europe – are mainly controlled by atmospheric inputs from distant anthropogenic sources.},\n\tnumber = {20},\n\turldate = {2017-02-07},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Klaminder, Jonatan and Farmer, John G. and MacKenzie, Angus B.},\n\tmonth = sep,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Contamination, Cryoturbation, Pb isotopes, Tundra soil},\n\tpages = {4344--4350},\n}\n\n\n\n\n\n Knowledge of the anthropogenic contribution to lead (Pb) concentrations in surface soils in high latitude ecosystems is central to our understanding of the extent of atmospheric Pb contamination. In this study, we reconstructed fallout of Pb at a remote sub-arctic region by using two ombrotrophic peat cores and assessed the extent to which this airborne Pb is able to explain the isotopic composition (206Pb/207Pb ratio) in the O-horizon of tundra soils. In the peat cores, long-range atmospheric fallout appeared to be the main source of Pb as indicated by temporal trends that followed the known European pollution history, i.e. accelerated fallout at the onset of industrialization and peak fallout around the 1960s–70s. The Pb isotopic composition of the O-horizon of podzolic tundra soil (206Pb/207Pb = 1.170 ± 0.002; mean ± SD) overlapped with that of the peat (206Pb/207Pb = 1.16 ± 0.01) representing a proxy for atmospheric aerosols, but was clearly different from that of the parent soil material (206Pb/207Pb = 1.22–1.30). This finding indicated that long-range fallout of atmospheric Pb is the main driver of Pb accumulation in podzolic tundra soil. In O-horizons of tundra soil weakly affected by cryoturbation (cryosols) however, the input of Pb from the underlying mineral soil increased as indicated by 206Pb/207Pb ratios of up to 1.20, a value closer to that of local soil minerals. Nevertheless, atmospheric Pb appeared to be the dominant source in this soil compartment. We conclude that Pb concentrations in the O-horizon of studied tundra soils – despite being much lower than in boreal soils and representative for one of the least exposed sites to atmospheric Pb contaminants in Europe – are mainly controlled by atmospheric inputs from distant anthropogenic sources.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lichen responses to nitrogen and phosphorus additions can be explained by the different symbiont responses.\n \n \n \n \n\n\n \n Johansson, O.; Olofsson, J.; Giesler, R.; and Palmqvist, K.\n\n\n \n\n\n\n New Phytologist, 191(3): 795–805. August 2011.\n \n\n\n\n
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\n\n\n@article{johansson_lichen_2011,\n\ttitle = {Lichen responses to nitrogen and phosphorus additions can be explained by the different symbiont responses},\n\tvolume = {191},\n\tissn = {1469-8137},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2011.03739.x/abstract},\n\tdoi = {10.1111/j.1469-8137.2011.03739.x},\n\tabstract = {* •Responses to simulated nitrogen (N) deposition with or without added phosphorus (P) were investigated for three contrasting lichen species – the N-sensitive Alectoria sarmentosa, the more N-tolerant Platismatia glauca and the N2-fixing Lobaria pulmonaria– in a field experiment.\n* •To examine whether nutrient limitation differed between the photobiont and the mycobiont within the lichen, the biomass responses of the respective bionts were estimated.\n* •The lichenized algal cells were generally N-limited, because N-stimulated algal growth in all three species. The mycobiont was P-limited in one species (A. sarmentosa), but the growth response of the mycobionts was complex, as fungal growth is also dependent on a reliable carbon export from the photobiont, which may have been the reason for the decrease of the mycobiont with N addition in P. glauca.\n* •Our findings showed that P availability was an important factor when studying effects of N deposition, as P supply can both mitigate and intensify the negative effects of N on epiphytic lichens.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {New Phytologist},\n\tauthor = {Johansson, Otilia and Olofsson, Johan and Giesler, Reiner and Palmqvist, Kristin},\n\tmonth = aug,\n\tyear = {2011},\n\tkeywords = {\\#nosource, chlorophyll a, epiphytic lichens, fertilization experiment, growth rate, nitrogen deposition, nutrient limitation, phosphorus, symbiosis},\n\tpages = {795--805},\n}\n\n\n\n\n\n * •Responses to simulated nitrogen (N) deposition with or without added phosphorus (P) were investigated for three contrasting lichen species – the N-sensitive Alectoria sarmentosa, the more N-tolerant Platismatia glauca and the N2-fixing Lobaria pulmonaria– in a field experiment. * •To examine whether nutrient limitation differed between the photobiont and the mycobiont within the lichen, the biomass responses of the respective bionts were estimated. * •The lichenized algal cells were generally N-limited, because N-stimulated algal growth in all three species. The mycobiont was P-limited in one species (A. sarmentosa), but the growth response of the mycobionts was complex, as fungal growth is also dependent on a reliable carbon export from the photobiont, which may have been the reason for the decrease of the mycobiont with N addition in P. glauca. * •Our findings showed that P availability was an important factor when studying effects of N deposition, as P supply can both mitigate and intensify the negative effects of N on epiphytic lichens.\n
\n\n\n\n \n\n \n \n \n \n \n \n Within- and Across-Species Responses of Plant Traits and Litter Decomposition to Elevation across Contrasting Vegetation Types in Subarctic Tundra.\n \n \n \n \n\n\n \n Sundqvist, M. K.; Giesler, R.; and Wardle, D. A.\n\n\n \n\n\n\n PLOS ONE, 6(10): e27056. October 2011.\n \n\n\n\n
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\n\n\n@article{sundqvist_within-_2011,\n\ttitle = {Within- and {Across}-{Species} {Responses} of {Plant} {Traits} and {Litter} {Decomposition} to {Elevation} across {Contrasting} {Vegetation} {Types} in {Subarctic} {Tundra}},\n\tvolume = {6},\n\tissn = {1932-6203},\n\turl = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0027056},\n\tdoi = {10.1371/journal.pone.0027056},\n\tabstract = {Elevational gradients are increasingly recognized as a valuable tool for understanding how community and ecosystem properties respond to climatic factors, but little is known about how plant traits and their effects on ecosystem processes respond to elevation. We studied the response of plant leaf and litter traits, and litter decomposability across a gradient of elevation, and thus temperature, in subarctic tundra in northern Sweden for each of two contrasting vegetation types, heath and meadow, dominated by dwarf shrubs and herbaceous plants respectively. This was done at each of three levels; across species, within individual species, and the plant community using a community weighted average approach. Several leaf and litter traits shifted with increasing elevation in a manner consistent with greater conservation of nutrients at all three levels, and the most consistent response was an increase in tissue N to P ratio. However, litter decomposition was less directly responsive to elevation because the leaf and litter traits which were most responsive to elevation were not necessarily those responsible for driving decomposition. At the community level, the response to elevation of foliar and litter traits, and decomposability, varied greatly among the two vegetation types, highlighting the importance of vegetation type in determining ecological responses to climatic factors such as temperature. Finally our results highlight how understanding the responses of leaf and litter characteristics of functionally distinct vegetation types, and the processes that they drive, to temperature helps provide insights about how future climate change could affect tundra ecosystems.},\n\tnumber = {10},\n\turldate = {2017-02-07},\n\tjournal = {PLOS ONE},\n\tauthor = {Sundqvist, Maja K. and Giesler, Reiner and Wardle, David A.},\n\tmonth = oct,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Decomposition, Ecosystem functioning, Ecosystems, Leaves, Plant communities, Plants, climate change, tundra},\n\tpages = {e27056},\n}\n\n\n\n\n\n Elevational gradients are increasingly recognized as a valuable tool for understanding how community and ecosystem properties respond to climatic factors, but little is known about how plant traits and their effects on ecosystem processes respond to elevation. We studied the response of plant leaf and litter traits, and litter decomposability across a gradient of elevation, and thus temperature, in subarctic tundra in northern Sweden for each of two contrasting vegetation types, heath and meadow, dominated by dwarf shrubs and herbaceous plants respectively. This was done at each of three levels; across species, within individual species, and the plant community using a community weighted average approach. Several leaf and litter traits shifted with increasing elevation in a manner consistent with greater conservation of nutrients at all three levels, and the most consistent response was an increase in tissue N to P ratio. However, litter decomposition was less directly responsive to elevation because the leaf and litter traits which were most responsive to elevation were not necessarily those responsible for driving decomposition. At the community level, the response to elevation of foliar and litter traits, and decomposability, varied greatly among the two vegetation types, highlighting the importance of vegetation type in determining ecological responses to climatic factors such as temperature. Finally our results highlight how understanding the responses of leaf and litter characteristics of functionally distinct vegetation types, and the processes that they drive, to temperature helps provide insights about how future climate change could affect tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Land use and land cover change in Arctic Russia: Ecological and social implications of industrial development.\n \n \n \n \n\n\n \n Kumpula, T.; Pajunen, A.; Kaarlejärvi, E.; Forbes, B. C.; and Stammler, F.\n\n\n \n\n\n\n Global Environmental Change, 21(2): 550–562. May 2011.\n \n\n\n\n
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\n\n\n@article{kumpula_land_2011,\n\ttitle = {Land use and land cover change in {Arctic} {Russia}: {Ecological} and social implications of industrial development},\n\tvolume = {21},\n\tissn = {0959-3780},\n\tshorttitle = {Land use and land cover change in {Arctic} {Russia}},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0959378010001342},\n\tdoi = {10.1016/j.gloenvcha.2010.12.010},\n\tabstract = {Sizable areas in northwestern arctic Russia have undergone fundamental change in recent decades as the exploration of vast hydrocarbon deposits has intensified. We undertook two case studies on the influence of oil and gas activities within neighbouring federal districts in the tundra zone. Employing a strongly interdisciplinary approach, we studied the ecological, spatial and social dimensions of the visible and perceived changes in land use and land cover. Our data are derived from field sampling, remote sensing and intensive participant observation with indigenous Nenets reindeer herders and non-indigenous workers. Important trends include the rapid expansion of infrastructure, a large influx of workers who compete for freshwater fish, and extensive transformation from shrub- to grass- and sedge-dominated tundra. The latter represents an alternative ecosystem state that is likely to persist indefinitely. On terrain disturbed by off-road vehicle traffic, reindeer pastures’ vegetation regenerates with fewer species among which grasses and sedges dominate, thus reducing biodiversity. To have maximum forage value such pastures must be accessible and free of trash, petro-chemicals and feral dogs. We found that a wide range of direct and indirect impacts, both ecological and social, accumulate in space and time such that the combined influence is effectively regional rather than local, depending in part on the placement of facilities. While incoming workers commonly commit poaching, they also serve as exchange partners, making barter for goods possible in remote locations. In general, the same positive and negative impacts of the presence of industry were mentioned in each study region. Even using very high-resolution remote sensing data (Quickbird-2) it is not possible to determine fully the amount of degraded territory in modern oil and gas fields. With regard to policy, both biophysical and social impacts could be substantially reduced if information flow between herders and workers were to be optimized.},\n\tnumber = {2},\n\turldate = {2017-02-08},\n\tjournal = {Global Environmental Change},\n\tauthor = {Kumpula, Timo and Pajunen, Anu and Kaarlejärvi, Elina and Forbes, Bruce C. and Stammler, Florian},\n\tmonth = may,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Human impact, Nenets nomadism, Off-road traffic, Oil \\& gas activities, Salix, reindeer, remote sensing},\n\tpages = {550--562},\n}\n\n\n\n\n\n Sizable areas in northwestern arctic Russia have undergone fundamental change in recent decades as the exploration of vast hydrocarbon deposits has intensified. We undertook two case studies on the influence of oil and gas activities within neighbouring federal districts in the tundra zone. Employing a strongly interdisciplinary approach, we studied the ecological, spatial and social dimensions of the visible and perceived changes in land use and land cover. Our data are derived from field sampling, remote sensing and intensive participant observation with indigenous Nenets reindeer herders and non-indigenous workers. Important trends include the rapid expansion of infrastructure, a large influx of workers who compete for freshwater fish, and extensive transformation from shrub- to grass- and sedge-dominated tundra. The latter represents an alternative ecosystem state that is likely to persist indefinitely. On terrain disturbed by off-road vehicle traffic, reindeer pastures’ vegetation regenerates with fewer species among which grasses and sedges dominate, thus reducing biodiversity. To have maximum forage value such pastures must be accessible and free of trash, petro-chemicals and feral dogs. We found that a wide range of direct and indirect impacts, both ecological and social, accumulate in space and time such that the combined influence is effectively regional rather than local, depending in part on the placement of facilities. While incoming workers commonly commit poaching, they also serve as exchange partners, making barter for goods possible in remote locations. In general, the same positive and negative impacts of the presence of industry were mentioned in each study region. Even using very high-resolution remote sensing data (Quickbird-2) it is not possible to determine fully the amount of degraded territory in modern oil and gas fields. With regard to policy, both biophysical and social impacts could be substantially reduced if information flow between herders and workers were to be optimized.\n
\n\n\n\n \n\n \n \n \n \n \n \n How do bryophytes govern generative recruitment of vascular plants?.\n \n \n \n \n\n\n \n Soudzilovskaia, N. A.; Graae, B. J.; Douma, J. C.; Grau, O.; Milbau, A.; Shevtsova, A.; Wolters, L.; and Cornelissen, J. H. C.\n\n\n \n\n\n\n New Phytologist, 190(4): 1019–1031. June 2011.\n \n\n\n\n
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\n\n\n@article{soudzilovskaia_how_2011,\n\ttitle = {How do bryophytes govern generative recruitment of vascular plants?},\n\tvolume = {190},\n\tissn = {1469-8137},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1469-8137.2011.03644.x/abstract},\n\tdoi = {10.1111/j.1469-8137.2011.03644.x},\n\tabstract = {* •Interactions between vascular plants and bryophytes determine plant community composition in many ecosystems. Yet, little is known about the importance of interspecific differences between bryophytes with respect to their effects on vascular plants. We compared the extent to which species-specific bryophyte effects on vascular plant generative recruitment depend on the following underlying mechanisms: allelopathy, mechanical obstruction, soil moisture and temperature control.\n* •We sowed 10 vascular plant species into monospecific mats of six chemically and structurally diverse bryophytes, and examined 1-yr seedling recruitment. Allelopathic effects were also assessed in a laboratory phyto-assay.\n* •Although all bryophytes suppressed vascular plant regeneration, there were significant differences between the bryophyte species. The lack of interactions indicated the absence of species-specific adaptations of vascular plants for recruitment in bryophyte mats. Differences between bryophyte species were best explained by alterations in temperature regime under bryophyte mats, mostly by reduced temperature amplitudes during germination. The temperature regime under bryophyte mats was well predicted by species-specific bryophyte cushion thickness. The fitness of established seedlings was not affected by the presence of bryophytes.\n* •Our results suggest that climatically or anthropogenically driven changes in the species’ composition of bryophyte communities have knock-on effects on vascular plant populations via generative reproduction.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2016-11-08},\n\tjournal = {New Phytologist},\n\tauthor = {Soudzilovskaia, Nadejda A. and Graae, Bente J. and Douma, Jacob C. and Grau, Oriol and Milbau, Ann and Shevtsova, Anna and Wolters, Loes and Cornelissen, Johannes H. C.},\n\tmonth = jun,\n\tyear = {2011},\n\tkeywords = {\\#nosource, Bryophyte, allelopathy, generative recruitment, germination, moisture, plant–plant interaction, seedling, temperature},\n\tpages = {1019--1031},\n}\n\n\n\n\n\n * •Interactions between vascular plants and bryophytes determine plant community composition in many ecosystems. Yet, little is known about the importance of interspecific differences between bryophytes with respect to their effects on vascular plants. We compared the extent to which species-specific bryophyte effects on vascular plant generative recruitment depend on the following underlying mechanisms: allelopathy, mechanical obstruction, soil moisture and temperature control. * •We sowed 10 vascular plant species into monospecific mats of six chemically and structurally diverse bryophytes, and examined 1-yr seedling recruitment. Allelopathic effects were also assessed in a laboratory phyto-assay. * •Although all bryophytes suppressed vascular plant regeneration, there were significant differences between the bryophyte species. The lack of interactions indicated the absence of species-specific adaptations of vascular plants for recruitment in bryophyte mats. Differences between bryophyte species were best explained by alterations in temperature regime under bryophyte mats, mostly by reduced temperature amplitudes during germination. The temperature regime under bryophyte mats was well predicted by species-specific bryophyte cushion thickness. The fitness of established seedlings was not affected by the presence of bryophytes. * •Our results suggest that climatically or anthropogenically driven changes in the species’ composition of bryophyte communities have knock-on effects on vascular plant populations via generative reproduction.\n
\n\n\n\n \n\n \n \n \n \n \n \n Strong microsite control of seedling recruitment in tundra.\n \n \n \n \n\n\n \n Graae, B. J.; Ejrnæs, R.; Lang, S. I.; Meineri, E.; Ibarra, P. T.; and Bruun, H. H.\n\n\n \n\n\n\n Oecologia, 166(2): 565–576. June 2011.\n \n\n\n\n
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\n\n\n@article{graae_strong_2011,\n\ttitle = {Strong microsite control of seedling recruitment in tundra},\n\tvolume = {166},\n\tissn = {0029-8549, 1432-1939},\n\turl = {http://link.springer.com/10.1007/s00442-010-1878-8},\n\tdoi = {10.1007/s00442-010-1878-8},\n\tabstract = {00041},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2016-11-08},\n\tjournal = {Oecologia},\n\tauthor = {Graae, Bente J. and Ejrnæs, Rasmus and Lang, Simone I. and Meineri, Eric and Ibarra, Pablo T. and Bruun, Hans Henrik},\n\tmonth = jun,\n\tyear = {2011},\n\tkeywords = {\\#nosource},\n\tpages = {565--576},\n}\n\n\n\n\n\n 00041\n
\n\n\n\n \n\n \n \n \n \n \n Stable carbon isotopes as indicators for environmental change in palsa peats.\n \n \n \n\n\n \n Alewell, C.; Giesler, R.; Klaminder, J.; Leifeld, J.; and Rollog, M.\n\n\n \n\n\n\n Biogeosciences, 8(7): 1769–1778. 2011.\n \n\n\n\n
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\n\n\n@article{alewell_stable_2011,\n\ttitle = {Stable carbon isotopes as indicators for environmental change in palsa peats},\n\tvolume = {8},\n\tissn = {1726-4170},\n\tdoi = {10.5194/bg-8-1769-2011},\n\tabstract = {Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by a high biodiversity and sensitive ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and induce a degradation of the mires. We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Soils dominated by aerobic degradation can be expected to have a clear increase of carbon isotopes (delta C-13) with depth, due to preferential release of C-12 during aerobic mineralization. In soils with suppressed degradation due to anoxic conditions, stable carbon isotope depth profiles are either more or less uniform indicating no or very low degradation or depth profiles turn to lighter values due to an enrichment of recalcitrant organic substances during anaerobic mineralisation which are depleted in C-13. The isotope depth profile of the peat in the water saturated depressions (hollows) at the yet undisturbed mire Storflaket indicated very low to no degradation but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent breaking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 and 25 cm. The age of these turning points was C-14 dated between 150 and 670 yr and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.},\n\tlanguage = {English},\n\tnumber = {7},\n\tjournal = {Biogeosciences},\n\tauthor = {Alewell, C. and Giesler, R. and Klaminder, J. and Leifeld, J. and Rollog, M.},\n\tyear = {2011},\n\tkeywords = {\\#nosource, Soil, Sphagnum, arctic mire, bog, climate, delta-c-13, methane release, organic-matter, permian-triassic boundary, phenolic constituents},\n\tpages = {1769--1778},\n}\n\n\n\n\n\n Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by a high biodiversity and sensitive ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and induce a degradation of the mires. We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Soils dominated by aerobic degradation can be expected to have a clear increase of carbon isotopes (delta C-13) with depth, due to preferential release of C-12 during aerobic mineralization. In soils with suppressed degradation due to anoxic conditions, stable carbon isotope depth profiles are either more or less uniform indicating no or very low degradation or depth profiles turn to lighter values due to an enrichment of recalcitrant organic substances during anaerobic mineralisation which are depleted in C-13. The isotope depth profile of the peat in the water saturated depressions (hollows) at the yet undisturbed mire Storflaket indicated very low to no degradation but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent breaking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 and 25 cm. The age of these turning points was C-14 dated between 150 and 670 yr and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.\n
\n\n\n\n \n\n \n \n \n \n \n Interactive effects of vegetation type and elevation on aboveground and belowground properties in a subarctic tundra.\n \n \n \n\n\n \n Sundqvist, M. K.; Giesler, R.; Graae, B. J.; Wallander, H.; Fogelberg, E.; and Wardle, D. A.\n\n\n \n\n\n\n Oikos, 120(1): 128–142. January 2011.\n \n\n\n\n
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\n\n\n@article{sundqvist_interactive_2011,\n\ttitle = {Interactive effects of vegetation type and elevation on aboveground and belowground properties in a subarctic tundra},\n\tvolume = {120},\n\tissn = {0030-1299},\n\tdoi = {10.1111/j.1600-0706.2010.18811.x},\n\tabstract = {An improved knowledge of how contrasting types of plant communities and their associated soil biota differ in their responses to climatic variables is important for better understanding the future impacts of climate change on terrestrial ecosystems. Elevational gradients serve as powerful study systems for answering questions on how ecological processes can be affected by changes in temperature and associated climatic variables. In this study, we evaluated how plant and soil microbial communities, and abiotic soil properties, change with increasing elevation in subarctic tundra in northern Sweden, for each of two dominant but highly contrasting vegetation types, namely heath (dominated by woody dwarf shrubs) and meadow (dominated by herbaceous species). To achieve this, we measured plant community characteristics, microbial community properties and several soil abiotic properties for both vegetation types across an elevation gradient of 500 to 1000 m. We found that the two vegetation types differed not only in several above- and belowground properties, but also in how these properties responded to elevation, pointing to important interactive effects between vegetation type and elevation. Specifically, for the heath, available soil nitrogen and phosphorus decreased with elevation whereas fungal dominance increased, while for the meadow, idiosyncratic responses to elevation for these variables were found. These differences in belowground responses to elevation among vegetation types were linked to shifts in the species and functional group composition of the vegetation. Our results highlight that these two dominant vegetation types in subarctic tundra differ greatly not only in fundamental aboveground and belowground properties, but also in how these properties respond to elevation and are therefore likely to be influenced by temperature. As such they highlight that vegetation type, and the soil abiotic properties that determine this, may serve as powerful determinants of how both aboveground and belowground properties respond to strong environmental gradients.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Oikos},\n\tauthor = {Sundqvist, Maja K. and Giesler, Reiner and Graae, Bente J. and Wallander, Hakan and Fogelberg, Elisabeth and Wardle, David A.},\n\tmonth = jan,\n\tyear = {2011},\n\tkeywords = {\\#nosource, alpine vegetation, climate-change, ecological dynamics, environmental-change, forests, gradient, nitrogen mineralization, plant diversity, soil respiration, swedish lapland},\n\tpages = {128--142},\n}\n\n\n\n\n\n An improved knowledge of how contrasting types of plant communities and their associated soil biota differ in their responses to climatic variables is important for better understanding the future impacts of climate change on terrestrial ecosystems. Elevational gradients serve as powerful study systems for answering questions on how ecological processes can be affected by changes in temperature and associated climatic variables. In this study, we evaluated how plant and soil microbial communities, and abiotic soil properties, change with increasing elevation in subarctic tundra in northern Sweden, for each of two dominant but highly contrasting vegetation types, namely heath (dominated by woody dwarf shrubs) and meadow (dominated by herbaceous species). To achieve this, we measured plant community characteristics, microbial community properties and several soil abiotic properties for both vegetation types across an elevation gradient of 500 to 1000 m. We found that the two vegetation types differed not only in several above- and belowground properties, but also in how these properties responded to elevation, pointing to important interactive effects between vegetation type and elevation. Specifically, for the heath, available soil nitrogen and phosphorus decreased with elevation whereas fungal dominance increased, while for the meadow, idiosyncratic responses to elevation for these variables were found. These differences in belowground responses to elevation among vegetation types were linked to shifts in the species and functional group composition of the vegetation. Our results highlight that these two dominant vegetation types in subarctic tundra differ greatly not only in fundamental aboveground and belowground properties, but also in how these properties respond to elevation and are therefore likely to be influenced by temperature. As such they highlight that vegetation type, and the soil abiotic properties that determine this, may serve as powerful determinants of how both aboveground and belowground properties respond to strong environmental gradients.\n
\n\n\n\n \n\n \n \n \n \n \n \n Microbial biomass and community composition in boreal lake sediments.\n \n \n \n \n\n\n \n Steger, K.; Premke, K.; Gudasz, C.; Sundh, I.; and Tranvik, L. J.\n\n\n \n\n\n\n Limnology and Oceanography, 56(2): 725–733. 2011.\n _eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2011.56.2.0725\n\n\n\n
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\n\n\n@article{steger_microbial_2011,\n\ttitle = {Microbial biomass and community composition in boreal lake sediments},\n\tvolume = {56},\n\tcopyright = {© 2011, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tissn = {1939-5590},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2011.56.2.0725},\n\tdoi = {10.4319/lo.2011.56.2.0725},\n\tabstract = {We used phospholipid fatty acids (PLFA) to determine microbial biomass and community structure in the sediments of eight boreal lakes with different loadings of allochthonous organic carbon and total phosphorus (TP) in the water during the course of a year. The total concentration of PLFA, an estimate of the microbial biomass, depended more on TP, a proxy for pelagic primary production, but not on dissolved organic carbon, a proxy for terrestrial organic carbon input. The composition of PLFAs varied considerably over time, demonstrating seasonal dynamics in microbial community composition. When PLFA profiles in all lakes and seasons are compared, community composition is more similar within season than within lakes.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-08-31},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Steger, Kristin and Premke, Katrin and Gudasz, Cristian and Sundh, Ingvar and Tranvik, Lars J.},\n\tyear = {2011},\n\tnote = {\\_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2011.56.2.0725},\n\tkeywords = {\\#nosource},\n\tpages = {725--733},\n}\n\n\n\n\n\n We used phospholipid fatty acids (PLFA) to determine microbial biomass and community structure in the sediments of eight boreal lakes with different loadings of allochthonous organic carbon and total phosphorus (TP) in the water during the course of a year. The total concentration of PLFA, an estimate of the microbial biomass, depended more on TP, a proxy for pelagic primary production, but not on dissolved organic carbon, a proxy for terrestrial organic carbon input. The composition of PLFAs varied considerably over time, demonstrating seasonal dynamics in microbial community composition. When PLFA profiles in all lakes and seasons are compared, community composition is more similar within season than within lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Multifunctionality and Diversity in Bacterial Biofilms.\n \n \n \n \n\n\n \n Peter, H.; Ylla, I.; Gudasz, C.; Romaní, A. M.; Sabater, S.; and Tranvik, L. J.\n\n\n \n\n\n\n PLOS ONE, 6(8): e23225. August 2011.\n Publisher: Public Library of Science\n\n\n\n
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\n\n\n@article{peter_multifunctionality_2011,\n\ttitle = {Multifunctionality and {Diversity} in {Bacterial} {Biofilms}},\n\tvolume = {6},\n\tissn = {1932-6203},\n\turl = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0023225},\n\tdoi = {10.1371/journal.pone.0023225},\n\tabstract = {Bacteria are highly diverse and drive a bulk of ecosystem processes. Analysis of relationships between diversity and single specific ecosystem processes neglects the possibility that different species perform multiple functions at the same time. The degradation of dissolved organic carbon (DOC) followed by respiration is a key bacterial function that is modulated by the availability of DOC and the capability to produce extracellular enzymes. In freshwater ecosystems, biofilms are metabolic hotspots and major sites of DOC degradation. We manipulated the diversity of biofilm forming communities which were fed with DOC differing in availability. We characterized community composition using molecular fingerprinting (T-RFLP) and measured functioning as oxygen consumption rates, the conversion of DOC in the medium, bacterial abundance and the activities of five specific enzymes. Based on assays of the extracellular enzyme activity, we calculated how the likelihood of sustaining multiple functions was affected by reduced diversity. Carbon source and biofilm age were strong drivers of community functioning, and we demonstrate how the likelihood of sustaining multifunctionality decreases with decreasing diversity.},\n\tlanguage = {en},\n\tnumber = {8},\n\turldate = {2020-08-31},\n\tjournal = {PLOS ONE},\n\tauthor = {Peter, Hannes and Ylla, Irene and Gudasz, Cristian and Romaní, Anna M. and Sabater, Sergi and Tranvik, Lars J.},\n\tmonth = aug,\n\tyear = {2011},\n\tnote = {Publisher: Public Library of Science},\n\tkeywords = {\\#nosource, Bacterial biofilms, Biodiversity, Biofilms, Ecosystem functioning, Enzymes, Oxygen consumption, Principal component analysis, Surface water},\n\tpages = {e23225},\n}\n\n\n\n\n\n Bacteria are highly diverse and drive a bulk of ecosystem processes. Analysis of relationships between diversity and single specific ecosystem processes neglects the possibility that different species perform multiple functions at the same time. The degradation of dissolved organic carbon (DOC) followed by respiration is a key bacterial function that is modulated by the availability of DOC and the capability to produce extracellular enzymes. In freshwater ecosystems, biofilms are metabolic hotspots and major sites of DOC degradation. We manipulated the diversity of biofilm forming communities which were fed with DOC differing in availability. We characterized community composition using molecular fingerprinting (T-RFLP) and measured functioning as oxygen consumption rates, the conversion of DOC in the medium, bacterial abundance and the activities of five specific enzymes. Based on assays of the extracellular enzyme activity, we calculated how the likelihood of sustaining multiple functions was affected by reduced diversity. Carbon source and biofilm age were strong drivers of community functioning, and we demonstrate how the likelihood of sustaining multifunctionality decreases with decreasing diversity.\n
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\n \n \n\n \n \n \n \n \n \n Potential remobilization of belowground permafrost carbon under future global warming.\n \n \n \n \n\n\n \n Kuhry, P.; Dorrepaal, E.; Hugelius, G.; Schuur, E. A. G.; and Tarnocai, C.\n\n\n \n\n\n\n Permafrost and Periglacial Processes, 21(2): 208–214. April 2010.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{kuhry_potential_2010,\n\ttitle = {Potential remobilization of belowground permafrost carbon under future global warming},\n\tvolume = {21},\n\tissn = {1045-6740},\n\turl = {https://doi.org/10.1002/ppp.684},\n\tdoi = {10.1002/ppp.684},\n\tabstract = {Abstract Research on permafrost carbon has dramatically increased in the past few years. A new estimate of 1672 Pg C of belowground organic carbon in the northern circumpolar permafrost region more than doubles the previous value and highlights the potential role of permafrost carbon in the Earth System. Uncertainties in this new estimate remain due to relatively few available pedon data for certain geographic sectors and the deeper cryoturbated soil horizons, and the large polygon size in the soil maps used for upscaling. The large permafrost carbon pool is not equally distributed across the landscape: peat deposits, cryoturbated soils and the loess-like deposits of the yedoma complex contain disproportionately large amounts of soil organic matter, often exhibiting a low degree of decomposition. Recent findings in Alaska and northern Sweden provide strong evidence that the deeper soil carbon in permafrost terrain is starting to be released, supporting previous reports from Siberia. The permafrost carbon pool is not yet fully integrated in climate and ecosystem models and an important objective should be to define typical pedons appropriate for model setups. The thawing permafrost carbon feedback needs to be included in model projections of future climate change. Copyright ? 2010 John Wiley \\& Sons, Ltd.},\n\tnumber = {2},\n\turldate = {2023-07-21},\n\tjournal = {Permafrost and Periglacial Processes},\n\tauthor = {Kuhry, P. and Dorrepaal, E. and Hugelius, G. and Schuur, E. A. G. and Tarnocai, C.},\n\tmonth = apr,\n\tyear = {2010},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {\\#nosource},\n\tpages = {208--214},\n}\n\n\n\n\n\n Abstract Research on permafrost carbon has dramatically increased in the past few years. A new estimate of 1672 Pg C of belowground organic carbon in the northern circumpolar permafrost region more than doubles the previous value and highlights the potential role of permafrost carbon in the Earth System. Uncertainties in this new estimate remain due to relatively few available pedon data for certain geographic sectors and the deeper cryoturbated soil horizons, and the large polygon size in the soil maps used for upscaling. The large permafrost carbon pool is not equally distributed across the landscape: peat deposits, cryoturbated soils and the loess-like deposits of the yedoma complex contain disproportionately large amounts of soil organic matter, often exhibiting a low degree of decomposition. Recent findings in Alaska and northern Sweden provide strong evidence that the deeper soil carbon in permafrost terrain is starting to be released, supporting previous reports from Siberia. The permafrost carbon pool is not yet fully integrated in climate and ecosystem models and an important objective should be to define typical pedons appropriate for model setups. The thawing permafrost carbon feedback needs to be included in model projections of future climate change. Copyright ? 2010 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Effect of Snow on Plants and Their Interactions with Herbivores.\n \n \n \n \n\n\n \n Torp, M.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2010.\n Publisher: Print&Media\n\n\n\n
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\n\n\n@phdthesis{torp_effect_2010,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {The {Effect} of {Snow} on {Plants} and {Their} {Interactions} with {Herbivores}},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-30444},\n\tabstract = {The ongoing climate changes are predicted to accelerate fast in arctic regions with increases in both temperatures and precipitation. Although the duration of snow cover is generally expected to de ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Torp, Mikaela},\n\tcollaborator = {Olofsson, Johan},\n\tyear = {2010},\n\tnote = {Publisher: Print\\&Media},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n The ongoing climate changes are predicted to accelerate fast in arctic regions with increases in both temperatures and precipitation. Although the duration of snow cover is generally expected to de ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Phosphorus availability and microbial respiration across biomes: from plantation forest to tundra.\n \n \n \n \n\n\n \n Esberg, C.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2010.\n Publisher: Umeå University\n\n\n\n
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\n\n\n@phdthesis{esberg_phosphorus_2010,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Phosphorus availability and microbial respiration across biomes: from plantation forest to tundra},\n\tshorttitle = {Phosphorus availability and microbial respiration across biomes},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-33732},\n\tabstract = {Phosphorus is the main limiting nutrient for plant growth in large areas of the world and the availability of phosphorus to plants and microbes can be strongly affected by soil properties. Even tho ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Esberg, Camilla},\n\tcollaborator = {Giesler, Reiner and Graae, Bente Jessen},\n\tyear = {2010},\n\tnote = {Publisher: Umeå University},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n Phosphorus is the main limiting nutrient for plant growth in large areas of the world and the availability of phosphorus to plants and microbes can be strongly affected by soil properties. Even tho ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Carbon metabolism in clear-water and brown-water lakes.\n \n \n \n \n\n\n \n Ask, J.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2010.\n Publisher: Institutionen för ekologi, miljö och geovetenskap, Department of Ecology and Environmental Sciences\n\n\n\n
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\n\n\n@phdthesis{ask_carbon_2010,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Carbon metabolism in clear-water and brown-water lakes},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-33488},\n\tabstract = {The trophic state of lakes is commonly defined by the concentration of nutrients in the water column. High nutrient concentrations generate high phytoplankton production, and lakes with low nutrien ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Ask, Jenny},\n\tcollaborator = {Karlsson, Jan and Jansson, Mats},\n\tyear = {2010},\n\tnote = {Publisher: Institutionen för ekologi, miljö och geovetenskap, Department of Ecology and Environmental Sciences},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n The trophic state of lakes is commonly defined by the concentration of nutrients in the water column. High nutrient concentrations generate high phytoplankton production, and lakes with low nutrien ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Lake secondary production fueled by rapid transfer of low molecular weight organic carbon from terrestrial sources to aquatic consumers.\n \n \n \n \n\n\n \n Berggren, M.; Ström, L.; Laudon, H.; Karlsson, J.; Jonsson, A.; Giesler, R.; Bergström, A.; and Jansson, M.\n\n\n \n\n\n\n Ecology Letters, 13(7): 870–880. July 2010.\n \n\n\n\n
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\n\n\n@article{berggren_lake_2010,\n\ttitle = {Lake secondary production fueled by rapid transfer of low molecular weight organic carbon from terrestrial sources to aquatic consumers},\n\tvolume = {13},\n\tissn = {1461-0248},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2010.01483.x/abstract},\n\tdoi = {10.1111/j.1461-0248.2010.01483.x},\n\tabstract = {Ecology Letters (2010) 13: 870–880 \nAbstract\nCarbon of terrestrial origin often makes up a significant share of consumer biomass in unproductive lake ecosystems. However, the mechanisms for terrestrial support of lake secondary production are largely unclear. By using a modelling approach, we show that terrestrial export of dissolved labile low molecular weight carbon (LMWC) compounds supported 80\\% (34–95\\%), 54\\% (19–90\\%) and 23\\% (7–45\\%) of the secondary production by bacteria, protozoa and metazoa, respectively, in a 7-km2 boreal lake (conservative to liberal estimates in brackets). Bacterial growth on LMWC was of similar magnitude as that of primary production (PP), and grazing on bacteria effectively channelled the LMWC carbon to higher trophic levels. We suggest that rapid turnover of forest LMWC pools enables continuous export of fresh photosynthates and other labile metabolites to aquatic systems, and that substantial transfer of LMWC from terrestrial sources to lake consumers can occur within a few days. Sequestration of LMWC of terrestrial origin, thus, helps explain high shares of terrestrial carbon in lake organisms and implies that lake food webs can be closely dependent on recent terrestrial PP.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-06},\n\tjournal = {Ecology Letters},\n\tauthor = {Berggren, M. and Ström, L. and Laudon, H. and Karlsson, J. and Jonsson, A. and Giesler, R. and Bergström, A.-K. and Jansson, M.},\n\tmonth = jul,\n\tyear = {2010},\n\tkeywords = {\\#nosource, Allochthony, lake secondary production, low molecular weight organic carbon},\n\tpages = {870--880},\n}\n\n\n\n\n\n Ecology Letters (2010) 13: 870–880 Abstract Carbon of terrestrial origin often makes up a significant share of consumer biomass in unproductive lake ecosystems. However, the mechanisms for terrestrial support of lake secondary production are largely unclear. By using a modelling approach, we show that terrestrial export of dissolved labile low molecular weight carbon (LMWC) compounds supported 80% (34–95%), 54% (19–90%) and 23% (7–45%) of the secondary production by bacteria, protozoa and metazoa, respectively, in a 7-km2 boreal lake (conservative to liberal estimates in brackets). Bacterial growth on LMWC was of similar magnitude as that of primary production (PP), and grazing on bacteria effectively channelled the LMWC carbon to higher trophic levels. We suggest that rapid turnover of forest LMWC pools enables continuous export of fresh photosynthates and other labile metabolites to aquatic systems, and that substantial transfer of LMWC from terrestrial sources to lake consumers can occur within a few days. Sequestration of LMWC of terrestrial origin, thus, helps explain high shares of terrestrial carbon in lake organisms and implies that lake food webs can be closely dependent on recent terrestrial PP.\n
\n\n\n\n \n\n \n \n \n \n \n \n High-resolution diatom δ18O records, from the last 150 years, reflecting changes in amount of winter precipitation in two sub-Arctic high-altitude lakes in the Swedish Scandes.\n \n \n \n \n\n\n \n Jonsson, C. E.; Rosqvist, G. C.; Leng, M. J.; Bigler, C.; Bergman, J.; Tillman, P. K.; and Sloane, H. J.\n\n\n \n\n\n\n Journal of Quaternary Science, 25(6): 918–930. September 2010.\n 00007\n\n\n\n
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\n\n\n@article{jonsson_high-resolution_2010,\n\ttitle = {High-resolution diatom δ{18O} records, from the last 150 years, reflecting changes in amount of winter precipitation in two sub-{Arctic} high-altitude lakes in the {Swedish} {Scandes}},\n\tvolume = {25},\n\tissn = {1099-1417},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1002/jqs.1372/abstract},\n\tdoi = {10.1002/jqs.1372},\n\tabstract = {Waters from high-altitude alpine lakes are mainly recharged by meteoric water. Because of seasonal variations in precipitation and temperature and relatively short hydraulic residence times, most high-altitude lakes have lake water isotopic compositions (δ18Olake) that fluctuate due to seasonality in water balance processes. Input from snowmelt, in particular, has a significant role in determining lake water δ18O. Here we compare two high-resolution δ18Odiatom records from lake sediments in the Swedish Scandes with instrumental data from the last century obtained from nearby meteorological stations. The time period AD 1900–1990 is characterised by an increase in winter precipitation and high winter/summer precipitation ratios and this is recorded in δ18Odiatom as decreasing trends. Lowest δ18Odiatom values and highest amount of winter precipitation are found around AD 1990 when the winter North Atlantic Oscillation index was above +2. We conclude that for the last 150 a the main factor affecting the δ18Odiatom signal in these sub-Arctic high-altitude lakes with short residence times has been changes in amount of winter precipitation and that δ18Odiatom derived from high-altitude lakes in the Swedish Scandes can be used as a winter precipitation proxy. Copyright © 2010 John Wiley \\& Sons, Ltd.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Quaternary Science},\n\tauthor = {Jonsson, Christina E. and Rosqvist, Gunhild C. and Leng, Melanie J. and Bigler, Christian and Bergman, Jonas and Tillman, Päivi Kaislahti and Sloane, Hilary J.},\n\tmonth = sep,\n\tyear = {2010},\n\tnote = {00007},\n\tkeywords = {\\#nosource, North Atlantic Oscillation, diatom silica, high-altitude lakes, oxygen isotopes, winter precipitation},\n\tpages = {918--930},\n}\n\n\n\n\n\n Waters from high-altitude alpine lakes are mainly recharged by meteoric water. Because of seasonal variations in precipitation and temperature and relatively short hydraulic residence times, most high-altitude lakes have lake water isotopic compositions (δ18Olake) that fluctuate due to seasonality in water balance processes. Input from snowmelt, in particular, has a significant role in determining lake water δ18O. Here we compare two high-resolution δ18Odiatom records from lake sediments in the Swedish Scandes with instrumental data from the last century obtained from nearby meteorological stations. The time period AD 1900–1990 is characterised by an increase in winter precipitation and high winter/summer precipitation ratios and this is recorded in δ18Odiatom as decreasing trends. Lowest δ18Odiatom values and highest amount of winter precipitation are found around AD 1990 when the winter North Atlantic Oscillation index was above +2. We conclude that for the last 150 a the main factor affecting the δ18Odiatom signal in these sub-Arctic high-altitude lakes with short residence times has been changes in amount of winter precipitation and that δ18Odiatom derived from high-altitude lakes in the Swedish Scandes can be used as a winter precipitation proxy. Copyright © 2010 John Wiley & Sons, Ltd.\n
\n\n\n\n \n\n \n \n \n \n \n \n Biomass and structure of planktonic communities along an air temperature gradient in subarctic Sweden.\n \n \n \n \n\n\n \n Jansson, M.; Jonsson, A.; Andersson, A.; and Karlsson, J.\n\n\n \n\n\n\n Freshwater Biology, 55(3): 691–700. March 2010.\n \n\n\n\n
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\n\n\n@article{jansson_biomass_2010,\n\ttitle = {Biomass and structure of planktonic communities along an air temperature gradient in subarctic {Sweden}},\n\tvolume = {55},\n\tissn = {1365-2427},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2427.2009.02310.x/abstract},\n\tdoi = {10.1111/j.1365-2427.2009.02310.x},\n\tabstract = {1. Air temperature will probably have pronounced effects on the composition of plankton communities in northern lake ecosystems, either via indirect effects on the export of essential elements from catchments or through direct effects of water temperature and the ice-free period on the behaviour of planktonic organisms. 2. We assessed the role of temperature by comparing planktonic communities in 15 lakes along a 6 °C air temperature gradient in subarctic Sweden. 3. We found that the biomass of phytoplankton, bacterioplankton and the total planktonic biomass were positively related to air temperature, probably as a result of climatic controls on the export of nitrogen from the catchment (which affects phytoplankton biomass) and dissolved organic carbon (affecting bacterioplankton biomass). 4. The structure of the zooplankton community, and top down effects on phytoplankton, were apparently not related to temperature but mainly to trophic interactions ultimately dependent on the presence of fish in the lakes. 5. Our results suggest that air temperature regimes and long-term warming can have strong effects on the planktonic biomass in high latitude lakes. Effects of temperature on the structure of the planktonic community might be less evident unless warming permits the invasion of fish into previous fishless lakes.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-06},\n\tjournal = {Freshwater Biology},\n\tauthor = {Jansson, Mats and Jonsson, Anders and Andersson, Agneta and Karlsson, Jan},\n\tmonth = mar,\n\tyear = {2010},\n\tkeywords = {\\#nosource, ecosystem, fish, lakes, phytoplankton, zooplankton},\n\tpages = {691--700},\n}\n\n\n\n\n\n 1. Air temperature will probably have pronounced effects on the composition of plankton communities in northern lake ecosystems, either via indirect effects on the export of essential elements from catchments or through direct effects of water temperature and the ice-free period on the behaviour of planktonic organisms. 2. We assessed the role of temperature by comparing planktonic communities in 15 lakes along a 6 °C air temperature gradient in subarctic Sweden. 3. We found that the biomass of phytoplankton, bacterioplankton and the total planktonic biomass were positively related to air temperature, probably as a result of climatic controls on the export of nitrogen from the catchment (which affects phytoplankton biomass) and dissolved organic carbon (affecting bacterioplankton biomass). 4. The structure of the zooplankton community, and top down effects on phytoplankton, were apparently not related to temperature but mainly to trophic interactions ultimately dependent on the presence of fish in the lakes. 5. Our results suggest that air temperature regimes and long-term warming can have strong effects on the planktonic biomass in high latitude lakes. Effects of temperature on the structure of the planktonic community might be less evident unless warming permits the invasion of fish into previous fishless lakes.\n
\n\n\n\n \n\n \n \n \n \n \n Development and application of sedimentary pigments for assessing effects of climatic and environmental changes on subarctic lakes in northern Sweden.\n \n \n \n\n\n \n Reuss, N.; Leavitt, P. R.; Hall, R. I.; Bigler, C.; and Hammarlund, D.\n\n\n \n\n\n\n Journal of Paleolimnology, 43(1): 149–169. January 2010.\n 00023\n\n\n\n
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\n\n\n@article{reuss_development_2010,\n\ttitle = {Development and application of sedimentary pigments for assessing effects of climatic and environmental changes on subarctic lakes in northern {Sweden}},\n\tvolume = {43},\n\tissn = {0921-2728},\n\tdoi = {10.1007/s10933-009-9323-x},\n\tabstract = {A surface-sediment survey of pigments in 100 lakes in the Scandes Mountains, northern Sweden, was combined with a reconstruction of Holocene sedimentary pigments from Lake Seukokjaure to assess the major factors regulating phototrophic communities, and how these controls may have changed during the period from the deglaciation (similar to 9700 cal. years BP) to the present. The study area covers a pronounced gradient of temperature and precipitation, and encompasses the subarctic tree line, an important ecotonal boundary in this region. Lake Seukokjaure is located in a presently treeless basin close to the modern tree line. The spatial survey of sedimentary pigments was analyzed using principle components analysis (PCA) and redundancy analysis (RDA). PCA explained 73-83\\% of variance in pigment abundance and composition, whereas RDA explained 22-32\\% of variation in fossil assemblages. Dissolved organic carbon (DOC) content of lake water, sediment delta(13)C, maximum lake depth, elevation and lake-water conductivity were all identified as environmental variables with significant association with pigment abundances in the spatial survey, although phototrophic communities of lakes situated in different vegetation zones (alpine, birch, conifer/birch) were incompletely distinguished by the ordinations. In the RDAs, the primary pigment variability occurred along a production gradient that was correlated negatively to water-column DOC content and delta(13)C signature of sediments. This pattern suggested that the important controls of primary production were light regime and terrestrial supplies of (13)C-depleted carbon. In contrast, depth, elevation and conductivity were found to be more important for the differentiation of the phototrophic community composition. Application of these spatial survey results to the Holocene sediment record of Lake Seukokjaure demonstrated the importance of DOC for the temporal development of the lake, from an early state of high production to a period of slight oligotrophication. In general, the algal changes were regulated by the interaction of DOC and conductivity, although transitions in the phototrophic community during the late Holocene were less easily interpreted. Terrestrial vegetation development thus appears to be of utmost importance for the regulation of primary production in oligotrophic alpine and subarctic lakes and climate impacts on lakes, whereas other basin-specific factors may control the ontogeny of algal community composition.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Reuss, Nina and Leavitt, Peter R. and Hall, Roland I. and Bigler, Christian and Hammarlund, Dan},\n\tmonth = jan,\n\tyear = {2010},\n\tnote = {00023},\n\tkeywords = {\\#nosource, DOC, Phototrophic community, Pigments, abisko, air-temperature, climate, dissolved organic-carbon, finnish-lapland, fossil pigments, glacier bay, great-plains, hplc, nutrient limitation, phytoplankton biomass, subarctic lake, water-quality},\n\tpages = {149--169},\n}\n\n\n\n\n\n A surface-sediment survey of pigments in 100 lakes in the Scandes Mountains, northern Sweden, was combined with a reconstruction of Holocene sedimentary pigments from Lake Seukokjaure to assess the major factors regulating phototrophic communities, and how these controls may have changed during the period from the deglaciation (similar to 9700 cal. years BP) to the present. The study area covers a pronounced gradient of temperature and precipitation, and encompasses the subarctic tree line, an important ecotonal boundary in this region. Lake Seukokjaure is located in a presently treeless basin close to the modern tree line. The spatial survey of sedimentary pigments was analyzed using principle components analysis (PCA) and redundancy analysis (RDA). PCA explained 73-83% of variance in pigment abundance and composition, whereas RDA explained 22-32% of variation in fossil assemblages. Dissolved organic carbon (DOC) content of lake water, sediment delta(13)C, maximum lake depth, elevation and lake-water conductivity were all identified as environmental variables with significant association with pigment abundances in the spatial survey, although phototrophic communities of lakes situated in different vegetation zones (alpine, birch, conifer/birch) were incompletely distinguished by the ordinations. In the RDAs, the primary pigment variability occurred along a production gradient that was correlated negatively to water-column DOC content and delta(13)C signature of sediments. This pattern suggested that the important controls of primary production were light regime and terrestrial supplies of (13)C-depleted carbon. In contrast, depth, elevation and conductivity were found to be more important for the differentiation of the phototrophic community composition. Application of these spatial survey results to the Holocene sediment record of Lake Seukokjaure demonstrated the importance of DOC for the temporal development of the lake, from an early state of high production to a period of slight oligotrophication. In general, the algal changes were regulated by the interaction of DOC and conductivity, although transitions in the phototrophic community during the late Holocene were less easily interpreted. Terrestrial vegetation development thus appears to be of utmost importance for the regulation of primary production in oligotrophic alpine and subarctic lakes and climate impacts on lakes, whereas other basin-specific factors may control the ontogeny of algal community composition.\n
\n\n\n\n \n\n \n \n \n \n \n \n Fourier transform infrared spectroscopy, a new method for rapid determination of total organic and inorganic carbon and biogenic silica concentration in lake sediments.\n \n \n \n \n\n\n \n Rosén, P.; Vogel, H.; Cunningham, L.; Reuss, N.; Conley, D. J.; and Persson, P.\n\n\n \n\n\n\n Journal of Paleolimnology, 43(2): 247–259. February 2010.\n 00052\n\n\n\n
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\n\n\n@article{rosen_fourier_2010,\n\ttitle = {Fourier transform infrared spectroscopy, a new method for rapid determination of total organic and inorganic carbon and biogenic silica concentration in lake sediments},\n\tvolume = {43},\n\tissn = {0921-2728, 1573-0417},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1007/s10933-009-9329-4},\n\tdoi = {10.1007/s10933-009-9329-4},\n\tabstract = {We demonstrate the use of Fourier transform infrared spectroscopy (FTIRS) to make quantitative measures of total organic carbon (TOC), total inorganic carbon (TIC) and biogenic silica (BSi) concentrations in sediment. FTIRS is a fast and cost-effective technique and only small sediment samples are needed (0.01 g). Statistically significant models were developed using sediment samples from northern Sweden and were applied to sediment records from Sweden, northeast Siberia and Macedonia. The correlation between FTIRS-inferred values and amounts of biogeochemical constituents assessed conventionally varied between r = 0.84–0.99 for TOC, r = 0.85–0.99 for TIC, and r = 0.68–0.94 for BSi. Because FTIR spectra contain information on a large number of both inorganic and organic components, there is great potential for FTIRS to become an important tool in paleolimnology.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2016-11-09},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Rosén, Peter and Vogel, Hendrik and Cunningham, Laura and Reuss, Nina and Conley, Daniel J. and Persson, Per},\n\tmonth = feb,\n\tyear = {2010},\n\tnote = {00052},\n\tkeywords = {\\#nosource},\n\tpages = {247--259},\n}\n\n\n\n\n\n We demonstrate the use of Fourier transform infrared spectroscopy (FTIRS) to make quantitative measures of total organic carbon (TOC), total inorganic carbon (TIC) and biogenic silica (BSi) concentrations in sediment. FTIRS is a fast and cost-effective technique and only small sediment samples are needed (0.01 g). Statistically significant models were developed using sediment samples from northern Sweden and were applied to sediment records from Sweden, northeast Siberia and Macedonia. The correlation between FTIRS-inferred values and amounts of biogeochemical constituents assessed conventionally varied between r = 0.84–0.99 for TOC, r = 0.85–0.99 for TIC, and r = 0.68–0.94 for BSi. Because FTIR spectra contain information on a large number of both inorganic and organic components, there is great potential for FTIRS to become an important tool in paleolimnology.\n
\n\n\n\n \n\n \n \n \n \n \n Rock Firefinch Lagonosticta sanguinodorsalis in the Mandara Mountains, north-east Nigeria: a new subspecies?.\n \n \n \n\n\n \n Abalaka, J. L.; Ottosson, U.; Tende, T.; and Larson, K. W.\n\n\n \n\n\n\n African Bird Club Bulletin, 17(2): 210–211. 2010.\n 00001\n\n\n\n
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\n\n\n\n@article{abalaka_rock_2010,\n\ttitle = {Rock {Firefinch} {Lagonosticta} sanguinodorsalis in the {Mandara} {Mountains}, north-east {Nigeria}: a new subspecies?},\n\tvolume = {17},\n\tdoi = {10.5962/p.309915},\n\tnumber = {2},\n\tjournal = {African Bird Club Bulletin},\n\tauthor = {Abalaka, J. L. and Ottosson, Ulf and Tende, Talatu and Larson, Keith W.},\n\tyear = {2010},\n\tnote = {00001},\n\tkeywords = {\\#nosource},\n\tpages = {210--211},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Wetland development, permafrost history and nutrient cycling inferred from late Holocene peat and lake sediment records in subarctic Sweden.\n \n \n \n \n\n\n \n Kokfelt, U.; Reuss, N.; Struyf, E.; Sonesson, M.; Rundgren, M.; Skog, G.; Rosén, P.; and Hammarlund, D.\n\n\n \n\n\n\n Journal of Paleolimnology, 44(1): 327–342. June 2010.\n 00057\n\n\n\n
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\n\n\n@article{kokfelt_wetland_2010,\n\ttitle = {Wetland development, permafrost history and nutrient cycling inferred from late {Holocene} peat and lake sediment records in subarctic {Sweden}},\n\tvolume = {44},\n\tissn = {0921-2728, 1573-0417},\n\turl = {https://link.springer.com/article/10.1007/s10933-010-9406-8},\n\tdoi = {10.1007/s10933-010-9406-8},\n\tabstract = {Permafrost in peatlands of subarctic Sweden is presently thawing at accelerated rates, which raises questions about the destiny of stored carbon and nutrients and impacts on adjacent freshwater ecosystems. In this study we use peat and lake sediment records from the Stordalen palsa mire in northern Sweden to address the late Holocene (5,000 cal BP-present) development of the mire as well as related changes in carbon and nutrient cycling. Formation, sediment accumulation and biogeochemistry of two studied lakes are suggested to be largely controlled by the development of the mire and its permafrost dynamics. Peat inception took place at ca. 4,700 cal BP as a result of terrestrialisation. Onset of organic sedimentation in the adjacent lakes occurred at ca. 3,400 and 2,650 cal BP in response to mire expansion and permafrost aggradation, respectively. Mire erosion, possibly due to permafrost decay, led to re-deposition of peat into one of the lakes after ca. 2,100 cal BP, and stimulated primary productivity in the other lake at ca. 1,900–1,800 cal BP. Carbonate precipitation appears to have been suppressed when acidic poor fen and bog (palsa) communities dominated the catchment mire, and permafrost-induced changes in hydrology may further have affected the inflow of alkaline water from the catchment. Elevated contents of biogenic silica and diatom pigments in lake sediments during periods of poor fen and bog expansion further indicate that terrestrial vegetation influenced the amount of nutrients entering the lake. Increased productivity in the lake likely caused bottom-water anoxia in the downstream lake and led to recycling of sediment phosphorous, bringing the lake into a state of self-sustained eutrophication during two centuries preceding the onset of twentieth century permafrost thaw. Our results give insight into nutrient and permafrost dynamics in a subarctic wetland and imply that continued permafrost decay and related vegetation changes towards minerotrophy may increase carbon and nutrient storage of mire deposits and reduce nutrient fluxes in runoff. Rapid permafrost degradation may on the other hand lead to widespread mire erosion and to relatively short periods of significantly increased nutrient loading in adjacent lakes.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-06-14},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Kokfelt, Ulla and Reuss, Nina and Struyf, Eric and Sonesson, Mats and Rundgren, Mats and Skog, Göran and Rosén, Peter and Hammarlund, Dan},\n\tmonth = jun,\n\tyear = {2010},\n\tnote = {00057},\n\tkeywords = {\\#nosource},\n\tpages = {327--342},\n}\n\n\n\n\n\n Permafrost in peatlands of subarctic Sweden is presently thawing at accelerated rates, which raises questions about the destiny of stored carbon and nutrients and impacts on adjacent freshwater ecosystems. In this study we use peat and lake sediment records from the Stordalen palsa mire in northern Sweden to address the late Holocene (5,000 cal BP-present) development of the mire as well as related changes in carbon and nutrient cycling. Formation, sediment accumulation and biogeochemistry of two studied lakes are suggested to be largely controlled by the development of the mire and its permafrost dynamics. Peat inception took place at ca. 4,700 cal BP as a result of terrestrialisation. Onset of organic sedimentation in the adjacent lakes occurred at ca. 3,400 and 2,650 cal BP in response to mire expansion and permafrost aggradation, respectively. Mire erosion, possibly due to permafrost decay, led to re-deposition of peat into one of the lakes after ca. 2,100 cal BP, and stimulated primary productivity in the other lake at ca. 1,900–1,800 cal BP. Carbonate precipitation appears to have been suppressed when acidic poor fen and bog (palsa) communities dominated the catchment mire, and permafrost-induced changes in hydrology may further have affected the inflow of alkaline water from the catchment. Elevated contents of biogenic silica and diatom pigments in lake sediments during periods of poor fen and bog expansion further indicate that terrestrial vegetation influenced the amount of nutrients entering the lake. Increased productivity in the lake likely caused bottom-water anoxia in the downstream lake and led to recycling of sediment phosphorous, bringing the lake into a state of self-sustained eutrophication during two centuries preceding the onset of twentieth century permafrost thaw. Our results give insight into nutrient and permafrost dynamics in a subarctic wetland and imply that continued permafrost decay and related vegetation changes towards minerotrophy may increase carbon and nutrient storage of mire deposits and reduce nutrient fluxes in runoff. Rapid permafrost degradation may on the other hand lead to widespread mire erosion and to relatively short periods of significantly increased nutrient loading in adjacent lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Lake Ecosystem Responses to Holocene Climate Change at the Subarctic Tree-Line in Northern Sweden.\n \n \n \n \n\n\n \n Reuss, N. S.; Hammarlund, D.; Rundgren, M.; Segerström, U.; Eriksson, L.; and Rosén, P.\n\n\n \n\n\n\n Ecosystems, 13(3): 393–409. April 2010.\n 00036\n\n\n\n
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\n\n\n@article{reuss_lake_2010,\n\ttitle = {Lake {Ecosystem} {Responses} to {Holocene} {Climate} {Change} at the {Subarctic} {Tree}-{Line} in {Northern} {Sweden}},\n\tvolume = {13},\n\tissn = {1432-9840, 1435-0629},\n\turl = {https://link.springer.com/article/10.1007/s10021-010-9326-5},\n\tdoi = {10.1007/s10021-010-9326-5},\n\tabstract = {A Holocene sediment sequence from Lake Seukokjaure, a subarctic lake at tree-line in northern Sweden, was analyzed to assess major changes in the structure and functioning of the aquatic ecosystem in response to climate change and tree-line dynamics. The compiled multi-proxy data, including sedimentary pigments, diatoms, chironomids, pollen, biogenic silica (BSi), carbon (C), nitrogen (N) elemental and stable-isotope records, and total lake-water organic carbon (TOC) concentration inferred from near-infrared spectroscopy (NIRS), suggest that the Holocene development of Lake Seukokjaure was closely coupled to changes in terrestrial vegetation with associated soil development of the catchment, input of allochthonous organic carbon, and changes in the light regime of the lake. A relatively productive state just after deglaciation around 9700 to 7800 cal years BP was followed by a slight long-term decrease in primary production. The onset of the local tree-line retreat around 3200 cal years BP was accompanied by more diverse and altered chironomid and diatom assemblages and indications of destabilized soils in the catchment by an increase in variability and absolute values of δ13C. An abrupt drop in the C/N ratio around 1750 cal years BP was coupled to changes in the internal lake structure, in combination with changes in light and nutrient conditions, resulting in a shift in the phototrophic community from diatom dominance to increased influence of chlorophytes, likely dominated by an aquatic moss community. Thus, this study emphasizes the importance of indirect effects of climate change on tree-line lake ecosystems and complex interactions of in-lake processes during the Holocene.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-06-14},\n\tjournal = {Ecosystems},\n\tauthor = {Reuss, Nina S. and Hammarlund, Dan and Rundgren, Mats and Segerström, Ulf and Eriksson, Lars and Rosén, Peter},\n\tmonth = apr,\n\tyear = {2010},\n\tnote = {00036},\n\tkeywords = {\\#nosource},\n\tpages = {393--409},\n}\n\n\n\n\n\n A Holocene sediment sequence from Lake Seukokjaure, a subarctic lake at tree-line in northern Sweden, was analyzed to assess major changes in the structure and functioning of the aquatic ecosystem in response to climate change and tree-line dynamics. The compiled multi-proxy data, including sedimentary pigments, diatoms, chironomids, pollen, biogenic silica (BSi), carbon (C), nitrogen (N) elemental and stable-isotope records, and total lake-water organic carbon (TOC) concentration inferred from near-infrared spectroscopy (NIRS), suggest that the Holocene development of Lake Seukokjaure was closely coupled to changes in terrestrial vegetation with associated soil development of the catchment, input of allochthonous organic carbon, and changes in the light regime of the lake. A relatively productive state just after deglaciation around 9700 to 7800 cal years BP was followed by a slight long-term decrease in primary production. The onset of the local tree-line retreat around 3200 cal years BP was accompanied by more diverse and altered chironomid and diatom assemblages and indications of destabilized soils in the catchment by an increase in variability and absolute values of δ13C. An abrupt drop in the C/N ratio around 1750 cal years BP was coupled to changes in the internal lake structure, in combination with changes in light and nutrient conditions, resulting in a shift in the phototrophic community from diatom dominance to increased influence of chlorophytes, likely dominated by an aquatic moss community. Thus, this study emphasizes the importance of indirect effects of climate change on tree-line lake ecosystems and complex interactions of in-lake processes during the Holocene.\n
\n\n\n\n \n\n \n \n \n \n \n \n A paleoclimate record with tephrochronological age control for the last glacial-interglacial cycle from Lake Ohrid, Albania and Macedonia.\n \n \n \n \n\n\n \n Vogel, H.; Wagner, B.; Zanchetta, G.; Sulpizio, R.; and Rosén, P.\n\n\n \n\n\n\n Journal of Paleolimnology, 44(1): 295–310. June 2010.\n 00091\n\n\n\n
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\n\n\n@article{vogel_paleoclimate_2010,\n\ttitle = {A paleoclimate record with tephrochronological age control for the last glacial-interglacial cycle from {Lake} {Ohrid}, {Albania} and {Macedonia}},\n\tvolume = {44},\n\tissn = {0921-2728, 1573-0417},\n\turl = {https://link.springer.com/article/10.1007/s10933-009-9404-x},\n\tdoi = {10.1007/s10933-009-9404-x},\n\tabstract = {Lake Ohrid is probably of Pliocene age, and the oldest extant lake in Europe. In this study climatic and environmental changes during the last glacial-interglacial cycle are reconstructed using lithological, sedimentological, geochemical and physical proxy analysis of a 15-m-long sediment succession from Lake Ohrid. A chronological framework is derived from tephrochronology and radiocarbon dating, which yields a basal age of ca. 136 ka. The succession is not continuous, however, with a hiatus between ca. 97.6 and 81.7 ka. Sediment accumulation in course of the last climatic cycle is controlled by the complex interaction of a variety of climate-controlled parameters and their impact on catchment dynamics, limnology, and hydrology of the lake. Warm interglacial and cold glacial climate conditions can be clearly distinguished from organic matter, calcite, clastic detritus and lithostratigraphic data. During interglacial periods, short-term fluctuations are recorded by abrupt variations in organic matter and calcite content, indicating climatically-induced changes in lake productivity and hydrology. During glacial periods, high variability in the contents of coarse silt to fine sand sized clastic matter is probably a function of climatically-induced changes in catchment dynamics and wind activity. In some instances tephra layers provide potential stratigraphic markers for short-lived climate perturbations. Given their widespread distribution in sites across the region, tephra analysis has the potential to provide insight into variation in the impact of climate and environmental change across the Mediterranean.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-06-14},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Vogel, Hendrik and Wagner, Bernd and Zanchetta, Giovanni and Sulpizio, Roberto and Rosén, Peter},\n\tmonth = jun,\n\tyear = {2010},\n\tnote = {00091},\n\tkeywords = {\\#nosource},\n\tpages = {295--310},\n}\n\n\n\n\n\n Lake Ohrid is probably of Pliocene age, and the oldest extant lake in Europe. In this study climatic and environmental changes during the last glacial-interglacial cycle are reconstructed using lithological, sedimentological, geochemical and physical proxy analysis of a 15-m-long sediment succession from Lake Ohrid. A chronological framework is derived from tephrochronology and radiocarbon dating, which yields a basal age of ca. 136 ka. The succession is not continuous, however, with a hiatus between ca. 97.6 and 81.7 ka. Sediment accumulation in course of the last climatic cycle is controlled by the complex interaction of a variety of climate-controlled parameters and their impact on catchment dynamics, limnology, and hydrology of the lake. Warm interglacial and cold glacial climate conditions can be clearly distinguished from organic matter, calcite, clastic detritus and lithostratigraphic data. During interglacial periods, short-term fluctuations are recorded by abrupt variations in organic matter and calcite content, indicating climatically-induced changes in lake productivity and hydrology. During glacial periods, high variability in the contents of coarse silt to fine sand sized clastic matter is probably a function of climatically-induced changes in catchment dynamics and wind activity. In some instances tephra layers provide potential stratigraphic markers for short-lived climate perturbations. Given their widespread distribution in sites across the region, tephra analysis has the potential to provide insight into variation in the impact of climate and environmental change across the Mediterranean.\n
\n\n\n\n \n\n \n \n \n \n \n \n Climate driven release of carbon and mercury from permafrost mires increases mercury loading to sub-arctic lakes.\n \n \n \n \n\n\n \n Rydberg, J.; Klaminder, J.; Rosén, P.; and Bindler, R.\n\n\n \n\n\n\n Science of The Total Environment, 408(20): 4778–4783. September 2010.\n 00052\n\n\n\n
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\n\n\n@article{rydberg_climate_2010,\n\ttitle = {Climate driven release of carbon and mercury from permafrost mires increases mercury loading to sub-arctic lakes},\n\tvolume = {408},\n\tissn = {0048-9697},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0048969710006613},\n\tdoi = {10.1016/j.scitotenv.2010.06.056},\n\tabstract = {In sub-arctic and arctic regions mercury is an element of concern for both wildlife and humans. Over thousands of years large amounts of atmospherically deposited mercury, both from natural and anthropogenic sources, have been sequestered together with carbon in northern peatlands. Many of these peatlands are currently underlain by permafrost, which controls mire stability and hydrology. With the ongoing climate change there is concern that permafrost thawing will turn large areas of these northern peatlands from carbon/mercury-sinks into much wetter carbon/mercury-sources. Here we can show that such a change in mire structure in the sub-arctic Stordalen mire in northern Sweden actually is responsible for an increased export of mercury to the adjacent lake Inre Harrsjön. We also show that sediment mercury accumulation rates during a warm period in the pre-industrial past were higher than in the 1970s when atmospheric input peaked, indicating that in areas with permafrost, climate can have an effect on mercury loading to lakes as large as anthropogenic emissions. Thawing of permafrost and the subsequent export of carbon is a widespread phenomenon, and the projection is that it will increase even more in the near future. Together with our observations from Stordalen, this makes northern peatlands into a substantial source of mercury, at risk of being released into sensitive arctic freshwater and marine systems.},\n\tnumber = {20},\n\turldate = {2017-02-07},\n\tjournal = {Science of The Total Environment},\n\tauthor = {Rydberg, Johan and Klaminder, Jonatan and Rosén, Peter and Bindler, Richard},\n\tmonth = sep,\n\tyear = {2010},\n\tnote = {00052},\n\tkeywords = {\\#nosource, NIRS, Permafrost dynamics, Sediment, mercury, peat},\n\tpages = {4778--4783},\n}\n\n\n\n\n\n In sub-arctic and arctic regions mercury is an element of concern for both wildlife and humans. Over thousands of years large amounts of atmospherically deposited mercury, both from natural and anthropogenic sources, have been sequestered together with carbon in northern peatlands. Many of these peatlands are currently underlain by permafrost, which controls mire stability and hydrology. With the ongoing climate change there is concern that permafrost thawing will turn large areas of these northern peatlands from carbon/mercury-sinks into much wetter carbon/mercury-sources. Here we can show that such a change in mire structure in the sub-arctic Stordalen mire in northern Sweden actually is responsible for an increased export of mercury to the adjacent lake Inre Harrsjön. We also show that sediment mercury accumulation rates during a warm period in the pre-industrial past were higher than in the 1970s when atmospheric input peaked, indicating that in areas with permafrost, climate can have an effect on mercury loading to lakes as large as anthropogenic emissions. Thawing of permafrost and the subsequent export of carbon is a widespread phenomenon, and the projection is that it will increase even more in the near future. Together with our observations from Stordalen, this makes northern peatlands into a substantial source of mercury, at risk of being released into sensitive arctic freshwater and marine systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Reduced early growing season freezing resistance in alpine treeline plants under elevated atmospheric CO2.\n \n \n \n \n\n\n \n Martin, M.; Gavazov, K.; Körner, C.; Hättenschwiler, S.; and Rixen, C.\n\n\n \n\n\n\n Global Change Biology, 16(3): 1057–1070. March 2010.\n 00058\n\n\n\n
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\n\n\n@article{martin_reduced_2010,\n\ttitle = {Reduced early growing season freezing resistance in alpine treeline plants under elevated atmospheric {CO2}},\n\tvolume = {16},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.01987.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2009.01987.x},\n\tabstract = {The frequency of freezing events during the early growing season and the vulnerability to freezing of plants in European high-altitude environments could increase under future atmospheric and climate change. We tested early growing season freezing sensitivity in 10 species, from four plant functional types (PFTs) spanning three plant growth forms (PGFs), from a long-term in situ CO2 enrichment (566 vs. 370 ppm) and 2-year soil warming (+4 K) experiment at treeline in the Swiss Alps (Stillberg, Davos). By additionally tracking plant phenology, we distinguished indirect phenology-driven CO2 and warming effects from direct physiology-related effects on freezing sensitivity. The freezing damage threshold (lethal temperature 50) under ambient conditions of the 10 treeline species spanned from −6.7±0.3 °C (Larix decidua) to −9.9±0.6 °C (Vaccinium gaultherioides). PFT, but not PGF, explained a significant amount of this interspecific variation. Long-term exposure to elevated CO2 led to greater freezing sensitivity in multiple species but did not influence phenology, implying that physiological changes caused by CO2 enrichment were responsible for the effect. The elevated CO2 effect on freezing resistance was significant in leaves of Larix, Vaccinium myrtillus, and Gentiana punctata and marginally significant in leaves of Homogyne alpina and Avenella flexuosa. No significant CO2 effect was found in new shoots of Empetrum hermaphroditum or in leaves of Pinus uncinata, Leontodon helveticus, Melampyrum pratense, and V. gaultherioides. Soil warming led to advanced leaf expansion and reduced freezing resistance in V. myrtillus only, whereas Avenella showed greater freezing resistance when exposed to warming. No effect of soil warming was found in any of the other species. Effects of elevated CO2 and soil warming on freezing sensitivity were not consistent within PFTs or PGFs, suggesting that any future shifts in plant community composition due to increased damage from freezing events will likely occur at the individual species level.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Martin, Melissa and Gavazov, Konstantin and Körner, Christian and Hättenschwiler, Stephan and Rixen, Christian},\n\tmonth = mar,\n\tyear = {2010},\n\tnote = {00058},\n\tkeywords = {\\#nosource, FACE, LT50, climate change, elevated CO2, freezing resistance, temperature, treeline},\n\tpages = {1057--1070},\n}\n\n\n\n\n\n The frequency of freezing events during the early growing season and the vulnerability to freezing of plants in European high-altitude environments could increase under future atmospheric and climate change. We tested early growing season freezing sensitivity in 10 species, from four plant functional types (PFTs) spanning three plant growth forms (PGFs), from a long-term in situ CO2 enrichment (566 vs. 370 ppm) and 2-year soil warming (+4 K) experiment at treeline in the Swiss Alps (Stillberg, Davos). By additionally tracking plant phenology, we distinguished indirect phenology-driven CO2 and warming effects from direct physiology-related effects on freezing sensitivity. The freezing damage threshold (lethal temperature 50) under ambient conditions of the 10 treeline species spanned from −6.7±0.3 °C (Larix decidua) to −9.9±0.6 °C (Vaccinium gaultherioides). PFT, but not PGF, explained a significant amount of this interspecific variation. Long-term exposure to elevated CO2 led to greater freezing sensitivity in multiple species but did not influence phenology, implying that physiological changes caused by CO2 enrichment were responsible for the effect. The elevated CO2 effect on freezing resistance was significant in leaves of Larix, Vaccinium myrtillus, and Gentiana punctata and marginally significant in leaves of Homogyne alpina and Avenella flexuosa. No significant CO2 effect was found in new shoots of Empetrum hermaphroditum or in leaves of Pinus uncinata, Leontodon helveticus, Melampyrum pratense, and V. gaultherioides. Soil warming led to advanced leaf expansion and reduced freezing resistance in V. myrtillus only, whereas Avenella showed greater freezing resistance when exposed to warming. No effect of soil warming was found in any of the other species. Effects of elevated CO2 and soil warming on freezing sensitivity were not consistent within PFTs or PGFs, suggesting that any future shifts in plant community composition due to increased damage from freezing events will likely occur at the individual species level.\n
\n\n\n\n \n\n \n \n \n \n \n Adsorption, Desorption, and Surface-Promoted Hydrolysis of Glucose-1-Phosphate in Aqueous Goethite (alpha-FeOOH) Suspensions.\n \n \n \n\n\n \n Olsson, R.; Giesler, R.; Loring, J. S.; and Persson, P.\n\n\n \n\n\n\n Langmuir, 26(24): 18760–18770. December 2010.\n 00000\n\n\n\n
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\n\n\n@article{olsson_adsorption_2010,\n\ttitle = {Adsorption, {Desorption}, and {Surface}-{Promoted} {Hydrolysis} of {Glucose}-1-{Phosphate} in {Aqueous} {Goethite} (alpha-{FeOOH}) {Suspensions}},\n\tvolume = {26},\n\tissn = {0743-7463},\n\tdoi = {10.1021/la1026152},\n\tabstract = {Adsorption, desorption, and precipitation reactions at environmental interfaces govern the fate of phosphorus in terrestrial and aquatic environments. Typically, a substantial part of the total pool of phosphorus consists of organophosphate, and in this study we have focused on the interactions between glucose-I-phosphate (G I P) and goethite (alpha-FeOOH) particles. The adsorption and surface-promoted hydrolysis reactions have been studied at room temperature as a function of pH, time, and total concentration of GIP by means of quantitative batch experiments in combination with infrared spectroscopy. A novel simultaneous infrared and potentiometric titration (SI PT) technique has also been used to study the rates and mechanisms of desorption of the surface complexes. The results have shown that GIP adsorption occurs over a wide pH interval and at pH values above the isoelectric point of goethite (IEP(goethite) = 9.4), indicating a comparatively strong interaction with the particle surfaces. As evidenced by IR spectroscopy, GIP formed pH-dependent surface complexes on goethite, and investigations of both adsorption and desorption processes were consistent with a model including three types of surface complexes. These complexes interact monodentately with surface Fe but differ in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The apparent desorption rates were shown to be influenced by reaction pathways that include interconversion of surface species, which highlights the difficulty in determining the intrinsic desorption rates of individual surface complexes. Desorption results have also indicated that the molecular structures of surface complexes and the surface charge are two important determinants of GIP desorption rates. Finally, this study has shown that surface-promoted hydrolysis of GIP by goethite is base-catalyzed but that the extent of hydrolysis was small.},\n\tlanguage = {English},\n\tnumber = {24},\n\tjournal = {Langmuir},\n\tauthor = {Olsson, Rickard and Giesler, Reiner and Loring, John S. and Persson, Per},\n\tmonth = dec,\n\tyear = {2010},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Soil, arsenate, complexation, inositol hexaphosphate, interface, mechanisms, myoinositol hexaphosphate, organic phosphorus, phosphate, spectroscopy},\n\tpages = {18760--18770},\n}\n\n\n\n\n\n Adsorption, desorption, and precipitation reactions at environmental interfaces govern the fate of phosphorus in terrestrial and aquatic environments. Typically, a substantial part of the total pool of phosphorus consists of organophosphate, and in this study we have focused on the interactions between glucose-I-phosphate (G I P) and goethite (alpha-FeOOH) particles. The adsorption and surface-promoted hydrolysis reactions have been studied at room temperature as a function of pH, time, and total concentration of GIP by means of quantitative batch experiments in combination with infrared spectroscopy. A novel simultaneous infrared and potentiometric titration (SI PT) technique has also been used to study the rates and mechanisms of desorption of the surface complexes. The results have shown that GIP adsorption occurs over a wide pH interval and at pH values above the isoelectric point of goethite (IEP(goethite) = 9.4), indicating a comparatively strong interaction with the particle surfaces. As evidenced by IR spectroscopy, GIP formed pH-dependent surface complexes on goethite, and investigations of both adsorption and desorption processes were consistent with a model including three types of surface complexes. These complexes interact monodentately with surface Fe but differ in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The apparent desorption rates were shown to be influenced by reaction pathways that include interconversion of surface species, which highlights the difficulty in determining the intrinsic desorption rates of individual surface complexes. Desorption results have also indicated that the molecular structures of surface complexes and the surface charge are two important determinants of GIP desorption rates. Finally, this study has shown that surface-promoted hydrolysis of GIP by goethite is base-catalyzed but that the extent of hydrolysis was small.\n
\n\n\n\n \n\n \n \n \n \n \n \n CO2 supersaturation along the aquatic conduit in Swedish watersheds as constrained by terrestrial respiration, aquatic respiration and weathering.\n \n \n \n \n\n\n \n Humborg, C.; Mörth, C.; Sundbom, M.; Borg, H.; Blenckner, T.; Giesler, R.; and Ittekkot, V.\n\n\n \n\n\n\n Global Change Biology, 16(7): 1966–1978. July 2010.\n 00113\n\n\n\n
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\n\n\n@article{humborg_co2_2010,\n\ttitle = {{CO2} supersaturation along the aquatic conduit in {Swedish} watersheds as constrained by terrestrial respiration, aquatic respiration and weathering},\n\tvolume = {16},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.02092.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2009.02092.x},\n\tabstract = {We tested the hypothesis that CO2 supersaturation along the aquatic conduit over Sweden can be explained by processes other than aquatic respiration. A first generalized-additive model (GAM) analysis evaluating the relationships between single water chemistry variables and pCO2 in lakes and streams revealed that water chemistry variables typical for groundwater input, e.g., dissolved silicate (DSi) and Mg2+ had explanatory power similar to total organic carbon (TOC). Further GAM analyses on various lake size classes and stream orders corroborated the slightly higher explanatory power for DSi in lakes and Mg2+ for streams compared with TOC. Both DSi and TOC explained 22–46\\% of the pCO2 variability in various lake classes (0.01–{\\textgreater}100 km2) and Mg2+ and TOC explained 11–41\\% of the pCO2 variability in the various stream orders. This suggests that aquatic pCO2 has a strong groundwater signature. Terrestrial respiration is a significant source of the observed supersaturation and we may assume that both terrestrial respiration and aquatic respiration contributed equally to pCO2 efflux. pCO2 and TOC concentrations decreased with lake size suggesting that the longer water residence time allow greater equilibration of CO2 with the atmosphere and in-lake mineralization of TOC. For streams, we observed a decreasing trend in pCO2 with stream orders between 3 and 6. We calculated the total CO2 efflux from all Swedish lakes and streams to be 2.58 Tg C yr−1. Our analyses also demonstrated that 0.70 Tg C yr−1 are exported to the ocean by Swedish watersheds as HCO3− and CO32− of which about 0.56 Tg C yr−1 is also a residual from terrestrial respiration and constitute a long-term sink for atmospheric CO2. Taking all dissolved inorganic carbon (DIC) fluxes along the aquatic conduit into account will lower the estimated net ecosystem C exchange (NEE) by 2.02 Tg C yr−1, which corresponds to 10\\% of the NEE in Sweden.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Humborg, Christoph and Mörth, Carl-Magnus and Sundbom, Marcus and Borg, Hans and Blenckner, Thorsten and Giesler, Reiner and Ittekkot, Venugopalan},\n\tmonth = jul,\n\tyear = {2010},\n\tnote = {00113},\n\tkeywords = {\\#nosource, CO2 air–water exchange, aquatic respiration, net ecosystem C exchange, terrestrial respiration, weathering},\n\tpages = {1966--1978},\n}\n\n\n\n\n\n We tested the hypothesis that CO2 supersaturation along the aquatic conduit over Sweden can be explained by processes other than aquatic respiration. A first generalized-additive model (GAM) analysis evaluating the relationships between single water chemistry variables and pCO2 in lakes and streams revealed that water chemistry variables typical for groundwater input, e.g., dissolved silicate (DSi) and Mg2+ had explanatory power similar to total organic carbon (TOC). Further GAM analyses on various lake size classes and stream orders corroborated the slightly higher explanatory power for DSi in lakes and Mg2+ for streams compared with TOC. Both DSi and TOC explained 22–46% of the pCO2 variability in various lake classes (0.01–\\textgreater100 km2) and Mg2+ and TOC explained 11–41% of the pCO2 variability in the various stream orders. This suggests that aquatic pCO2 has a strong groundwater signature. Terrestrial respiration is a significant source of the observed supersaturation and we may assume that both terrestrial respiration and aquatic respiration contributed equally to pCO2 efflux. pCO2 and TOC concentrations decreased with lake size suggesting that the longer water residence time allow greater equilibration of CO2 with the atmosphere and in-lake mineralization of TOC. For streams, we observed a decreasing trend in pCO2 with stream orders between 3 and 6. We calculated the total CO2 efflux from all Swedish lakes and streams to be 2.58 Tg C yr−1. Our analyses also demonstrated that 0.70 Tg C yr−1 are exported to the ocean by Swedish watersheds as HCO3− and CO32− of which about 0.56 Tg C yr−1 is also a residual from terrestrial respiration and constitute a long-term sink for atmospheric CO2. Taking all dissolved inorganic carbon (DIC) fluxes along the aquatic conduit into account will lower the estimated net ecosystem C exchange (NEE) by 2.02 Tg C yr−1, which corresponds to 10% of the NEE in Sweden.\n
\n\n\n\n \n\n \n \n \n \n \n \n The use of open-top chambers in forests for evaluating warming effects on herbaceous understorey plants.\n \n \n \n \n\n\n \n Frenne, P. D.; Schrijver, A. D.; Graae, B. J.; Gruwez, R.; Tack, W.; Vandelook, F.; Hermy, M.; and Verheyen, K.\n\n\n \n\n\n\n Ecological Research, 25(1): 163–171. January 2010.\n 00026\n\n\n\n
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\n\n\n@article{frenne_use_2010,\n\ttitle = {The use of open-top chambers in forests for evaluating warming effects on herbaceous understorey plants},\n\tvolume = {25},\n\tissn = {0912-3814, 1440-1703},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1007/s11284-009-0640-3},\n\tdoi = {10.1007/s11284-009-0640-3},\n\tabstract = {Open-top chambers (OTCs) are widely used experimental warming devices in open-field ecosystems such as tundra and alpine heath. However, knowledge of their performance in temperate deciduous forest ecosystems is largely lacking. The application of OTCs in forests might become important in the future since the effects of climate warming on growth, reproduction, and future distribution of understorey forest herbs have rarely been investigated. Therefore, polycarbonate OTCs covered with (OTCs+GF) and without permeable polypropylene GardenFleece (OTCs−GF) were installed in a temperate deciduous forest to create an experimental warming gradient. Short-term responses in phenology, growth, and reproduction of a model understorey forest herb (Anemone nemorosa L.) to OTC installation were determined. In a second growing season, an in-depth study of multiple abiotic conditions inside OTCs−GF was performed. Both OTCs+GF and OTCs−GF raised air and soil temperature in a realistic manner (ca. +0.4°C to +1.15°C), but OTCs−GF only in the leafless period (up to +1.5°C monthly average soil temperature). The early flowering forest herb A. nemorosa also showed a clear phenotypic response to OTC installation. Based on these facts and the large ecological drawbacks associated with OTCs+GF (mostly in connection with a higher relative air humidity and a lower light quantity) and very modest abiotic changes in OTCs−GF, we encourage the use of OTCs−GF in deciduous forest ecosystems for evaluating climate-warming effects on early flowering understorey forest herbs. There is also a potential to use this warming method on later flowering species, but this needs further research.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2016-11-08},\n\tjournal = {Ecological Research},\n\tauthor = {Frenne, Pieter De and Schrijver, An De and Graae, Bente J. and Gruwez, Robert and Tack, Wesley and Vandelook, Filip and Hermy, Martin and Verheyen, Kris},\n\tmonth = jan,\n\tyear = {2010},\n\tnote = {00026},\n\tkeywords = {\\#nosource},\n\tpages = {163--171},\n}\n\n\n\n\n\n Open-top chambers (OTCs) are widely used experimental warming devices in open-field ecosystems such as tundra and alpine heath. However, knowledge of their performance in temperate deciduous forest ecosystems is largely lacking. The application of OTCs in forests might become important in the future since the effects of climate warming on growth, reproduction, and future distribution of understorey forest herbs have rarely been investigated. Therefore, polycarbonate OTCs covered with (OTCs+GF) and without permeable polypropylene GardenFleece (OTCs−GF) were installed in a temperate deciduous forest to create an experimental warming gradient. Short-term responses in phenology, growth, and reproduction of a model understorey forest herb (Anemone nemorosa L.) to OTC installation were determined. In a second growing season, an in-depth study of multiple abiotic conditions inside OTCs−GF was performed. Both OTCs+GF and OTCs−GF raised air and soil temperature in a realistic manner (ca. +0.4°C to +1.15°C), but OTCs−GF only in the leafless period (up to +1.5°C monthly average soil temperature). The early flowering forest herb A. nemorosa also showed a clear phenotypic response to OTC installation. Based on these facts and the large ecological drawbacks associated with OTCs+GF (mostly in connection with a higher relative air humidity and a lower light quantity) and very modest abiotic changes in OTCs−GF, we encourage the use of OTCs−GF in deciduous forest ecosystems for evaluating climate-warming effects on early flowering understorey forest herbs. There is also a potential to use this warming method on later flowering species, but this needs further research.\n
\n\n\n\n \n\n \n \n \n \n \n Lead Contamination of Subarctic Lakes and Its Response to Reduced Atmospheric Fallout: Can the Recovery Process Be Counteracted by the Ongoing Climate Change?.\n \n \n \n\n\n \n Klaminder, J.; Hammarlund, D.; Kokfelt, U.; Vonk, J. E.; and Bigler, C.\n\n\n \n\n\n\n Environmental Science & Technology, 44(7): 2335–2340. April 2010.\n 00017\n\n\n\n
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\n\n\n@article{klaminder_lead_2010,\n\ttitle = {Lead {Contamination} of {Subarctic} {Lakes} and {Its} {Response} to {Reduced} {Atmospheric} {Fallout}: {Can} the {Recovery} {Process} {Be} {Counteracted} by the {Ongoing} {Climate} {Change}?},\n\tvolume = {44},\n\tissn = {0013-936X},\n\tshorttitle = {Lead {Contamination} of {Subarctic} {Lakes} and {Its} {Response} to {Reduced} {Atmospheric} {Fallout}},\n\tdoi = {10.1021/es903025z},\n\tabstract = {Can a climate-triggered export of old contaminants from the soil alter the lead (Pb) contaminant burden of subarctic lakes? To address this question, we reconstructed the pollution history of three high latitude lakes situated in a region where a recent climatic shift has occurred. Dated sediment records were used as archives of past Pb inputs to the lakes, where the difference in the Pb-206/Pb-207 ratio between atmospheric contaminants (Pb-206/Pb-207 ratio {\\textless}1.16) and geogenic Pb in the catchment soil (Pb-206/Pb-207 ratio {\\textgreater}1.22) were used to trace fluxes of Pb contaminants. Lead contaminants were found in sediments deposited since Roman times. A significant export of Pb from the soil contaminant pool is indicated in two of the lakes surrounded by near-shore permafrost soils. Here, levels of Pb contaminants and Pb-206/Pb-207 ratios of sediments deposited after the 1970s appear not to have been strongly affected by the {\\textgreater}= 90\\% reduction in atmospheric deposition rates and increasing Pb-206/Pb-207 ratios of atmospheric Pb since the 1990s. We concluded that soil processes stimulated by the ongoing climate change at high latitudes might work counteractive to efforts to reduce contaminant levels in subarctic lakes.},\n\tlanguage = {English},\n\tnumber = {7},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Klaminder, Jonatan and Hammarlund, Dan and Kokfelt, Ulla and Vonk, Jorien E. and Bigler, Christian},\n\tmonth = apr,\n\tyear = {2010},\n\tnote = {00017},\n\tkeywords = {\\#nosource, Boreal forest, Holocene, deposition record, northern sweden, organic-rich, pollution, scotland, sediments, soils, upland catchment},\n\tpages = {2335--2340},\n}\n\n\n\n\n\n Can a climate-triggered export of old contaminants from the soil alter the lead (Pb) contaminant burden of subarctic lakes? To address this question, we reconstructed the pollution history of three high latitude lakes situated in a region where a recent climatic shift has occurred. Dated sediment records were used as archives of past Pb inputs to the lakes, where the difference in the Pb-206/Pb-207 ratio between atmospheric contaminants (Pb-206/Pb-207 ratio \\textless1.16) and geogenic Pb in the catchment soil (Pb-206/Pb-207 ratio \\textgreater1.22) were used to trace fluxes of Pb contaminants. Lead contaminants were found in sediments deposited since Roman times. A significant export of Pb from the soil contaminant pool is indicated in two of the lakes surrounded by near-shore permafrost soils. Here, levels of Pb contaminants and Pb-206/Pb-207 ratios of sediments deposited after the 1970s appear not to have been strongly affected by the \\textgreater= 90% reduction in atmospheric deposition rates and increasing Pb-206/Pb-207 ratios of atmospheric Pb since the 1990s. We concluded that soil processes stimulated by the ongoing climate change at high latitudes might work counteractive to efforts to reduce contaminant levels in subarctic lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Isotopic analysis of cyanobacterial nitrogen fixation associated with subarctic lichen and bryophyte species.\n \n \n \n \n\n\n \n Gavazov, K. S.; Soudzilovskaia, N. A.; Logtestijn, R. S. P. v.; Braster, M.; and Cornelissen, J. H. C.\n\n\n \n\n\n\n Plant and Soil, 333(1-2): 507–517. August 2010.\n 00031\n\n\n\n
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\n\n\n@article{gavazov_isotopic_2010,\n\ttitle = {Isotopic analysis of cyanobacterial nitrogen fixation associated with subarctic lichen and bryophyte species},\n\tvolume = {333},\n\tissn = {0032-079X, 1573-5036},\n\turl = {http://link.springer.com/article/10.1007/s11104-010-0374-6},\n\tdoi = {10.1007/s11104-010-0374-6},\n\tabstract = {Dinitrogen fixation by cyanobacteria is of particular importance for the nutrient economy of cold biomes, constituting the main pathway for new N supplies to tundra ecosystems. It is prevalent in cyanobacterial colonies on bryophytes and in obligate associations within cyanolichens. Recent studies, applying interspecific variation in plant functional traits to upscale species effects on ecosystems, have all but neglected cryptogams and their association with cyanobacteria. Here we looked for species-specific patterns that determine cryptogam-mediated rates of N2 fixation in the Subarctic. We hypothesised a contrast in N2 fixation rates (1) between the structurally and physiologically different lichens and bryophytes, and (2) within bryophytes based on their respective plant functional types. Throughout the survey we supplied 15N-labelled N2 gas to quantify fixation rates for monospecific moss, liverwort and lichen turfs. We sampled fifteen species in a design that captures spatial and temporal variations during the growing season in Abisko region, Sweden. We measured N2 fixation potential of each turf in a common environment and in its field sampling site, in order to embrace both comparativeness and realism. Cyanolichens and bryophytes differed significantly in their cyanobacterial N2 fixation capacity, which was not driven by microhabitat characteristics, but rather by morphology and physiology. Cyanolichens were much more prominent fixers than bryophytes per unit dry weight, but not per unit area due to their low specific thallus weight. Mosses did not exhibit consistent differences in N2 fixation rates across species and functional types. Liverworts did not fix detectable amounts of N2. Despite the very high rates of N2 fixation associated with cyanolichens, large cover of mosses per unit area at the landscape scale compensates for their lower fixation rates, thereby probably making them the primary regional atmospheric nitrogen sink.},\n\tlanguage = {en},\n\tnumber = {1-2},\n\turldate = {2017-02-08},\n\tjournal = {Plant and Soil},\n\tauthor = {Gavazov, Konstantin S. and Soudzilovskaia, Nadejda A. and Logtestijn, Richard S. P. van and Braster, Martin and Cornelissen, Johannes H. C.},\n\tmonth = aug,\n\tyear = {2010},\n\tnote = {00031},\n\tkeywords = {\\#nosource, 15N, Interspecific variation, liverwort, moss, tundra},\n\tpages = {507--517},\n}\n\n\n\n\n\n Dinitrogen fixation by cyanobacteria is of particular importance for the nutrient economy of cold biomes, constituting the main pathway for new N supplies to tundra ecosystems. It is prevalent in cyanobacterial colonies on bryophytes and in obligate associations within cyanolichens. Recent studies, applying interspecific variation in plant functional traits to upscale species effects on ecosystems, have all but neglected cryptogams and their association with cyanobacteria. Here we looked for species-specific patterns that determine cryptogam-mediated rates of N2 fixation in the Subarctic. We hypothesised a contrast in N2 fixation rates (1) between the structurally and physiologically different lichens and bryophytes, and (2) within bryophytes based on their respective plant functional types. Throughout the survey we supplied 15N-labelled N2 gas to quantify fixation rates for monospecific moss, liverwort and lichen turfs. We sampled fifteen species in a design that captures spatial and temporal variations during the growing season in Abisko region, Sweden. We measured N2 fixation potential of each turf in a common environment and in its field sampling site, in order to embrace both comparativeness and realism. Cyanolichens and bryophytes differed significantly in their cyanobacterial N2 fixation capacity, which was not driven by microhabitat characteristics, but rather by morphology and physiology. Cyanolichens were much more prominent fixers than bryophytes per unit dry weight, but not per unit area due to their low specific thallus weight. Mosses did not exhibit consistent differences in N2 fixation rates across species and functional types. Liverworts did not fix detectable amounts of N2. Despite the very high rates of N2 fixation associated with cyanolichens, large cover of mosses per unit area at the landscape scale compensates for their lower fixation rates, thereby probably making them the primary regional atmospheric nitrogen sink.\n
\n\n\n\n \n\n \n \n \n \n \n \n Cumulative Effects of Rapid Land-Cover and Land-Use Changes on the Yamal Peninsula, Russia.\n \n \n \n \n\n\n \n Walker, D. A.; Forbes, B. C.; Leibman, M. O.; Epstein, H. E.; Bhatt, U. S.; Comiso, J. C.; Drozdov, D. S.; Gubarkov, A. A.; Jia, G. J.; Kaarlejärvi, E.; Kaplan, J. O.; Khomutov, A. V.; Kofinas, G. P.; Kumpula, T.; Kuss, P.; Moskalenko, N. G.; Meschtyb, N. A.; Pajunen, A.; Raynolds, M. K.; Romanovsky, V. E.; Stammler, F.; and Yu, Q.\n\n\n \n\n\n\n In Gutman, G.; and Reissell, A., editor(s), Eurasian Arctic Land Cover and Land Use in a Changing Climate, pages 207–236. Springer Netherlands, 2010.\n 00024\n\n\n\n
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\n\n\n@incollection{walker_cumulative_2010,\n\ttitle = {Cumulative {Effects} of {Rapid} {Land}-{Cover} and {Land}-{Use} {Changes} on the {Yamal} {Peninsula}, {Russia}},\n\tcopyright = {©2011 Springer Science+Business Media B.V.},\n\tisbn = {978-90-481-9117-8 978-90-481-9118-5},\n\turl = {http://link.springer.com/chapter/10.1007/978-90-481-9118-5_9},\n\tabstract = {The Yamal Peninsula in northwest Siberia is undergoing some of the most rapid land-cover and land-use changes in the Arctic due to a combination of gas development, reindeer herding, and climate change. Unusual geological conditions (nutrient-poor sands, massive ground ice and extensive landslides) exacerbate the impacts. These changes will likely increase markedly as transportation corridors are built to transport the gas to market. Understanding the nature, extent, causes and consequences (i.e., the cumulative effects) of the past and ongoing rapid changes on the Yamal is important for effective, long-term decision-making and planning. The cumulative effects to vegetation are the focus of this chapter because the plants are a critical component of the Yamal landscape that support the indigenous Nenets people and their reindeer and also protect the underlying ice-rich permafrost from melting. We are using a combination of ground-based studies (a transect of five locations across the Yamal), remote-sensing studies, and analyses of Nenets land-use activities to develop vegetation-change models that can be used to help anticipate future states of the tundra and how those changes might affect traditional reindeer herding practices and the thermal state of the permafrost. This chapter provides an overview of the approach, some early results, and recommendations for expanding the concept of cumulative-effects analysis to include examining the simultaneous and interactive effects of multiple drivers of change.},\n\tlanguage = {en},\n\turldate = {2017-02-13},\n\tbooktitle = {Eurasian {Arctic} {Land} {Cover} and {Land} {Use} in a {Changing} {Climate}},\n\tpublisher = {Springer Netherlands},\n\tauthor = {Walker, Donald A. and Forbes, Bruce C. and Leibman, Marina O. and Epstein, Howard E. and Bhatt, Uma S. and Comiso, Josefino C. and Drozdov, Dmitri S. and Gubarkov, Anatoly A. and Jia, Gensuo J. and Kaarlejärvi, Elina and Kaplan, Jed O. and Khomutov, Artem V. and Kofinas, Gary P. and Kumpula, Timo and Kuss, Patrick and Moskalenko, Natalia G. and Meschtyb, Nina A. and Pajunen, Anu and Raynolds, Martha K. and Romanovsky, Vladimir E. and Stammler, Florian and Yu, Qin},\n\teditor = {Gutman, Garik and Reissell, Anni},\n\tyear = {2010},\n\tnote = {00024},\n\tkeywords = {\\#nosource, Biogeosciences, Geographical Information Systems/Cartography, Remote Sensing/Photogrammetry, Social Sciences, general, Terrestial Ecology},\n\tpages = {207--236},\n}\n\n\n\n\n\n The Yamal Peninsula in northwest Siberia is undergoing some of the most rapid land-cover and land-use changes in the Arctic due to a combination of gas development, reindeer herding, and climate change. Unusual geological conditions (nutrient-poor sands, massive ground ice and extensive landslides) exacerbate the impacts. These changes will likely increase markedly as transportation corridors are built to transport the gas to market. Understanding the nature, extent, causes and consequences (i.e., the cumulative effects) of the past and ongoing rapid changes on the Yamal is important for effective, long-term decision-making and planning. The cumulative effects to vegetation are the focus of this chapter because the plants are a critical component of the Yamal landscape that support the indigenous Nenets people and their reindeer and also protect the underlying ice-rich permafrost from melting. We are using a combination of ground-based studies (a transect of five locations across the Yamal), remote-sensing studies, and analyses of Nenets land-use activities to develop vegetation-change models that can be used to help anticipate future states of the tundra and how those changes might affect traditional reindeer herding practices and the thermal state of the permafrost. This chapter provides an overview of the approach, some early results, and recommendations for expanding the concept of cumulative-effects analysis to include examining the simultaneous and interactive effects of multiple drivers of change.\n
\n\n\n\n \n\n \n \n \n \n \n Snow-induced changes in dwarf birch chemistry increase moth larval growth rate and level of herbivory.\n \n \n \n\n\n \n Torp, M.; Olofsson, J.; Witzell, J.; and Baxter, R.\n\n\n \n\n\n\n Polar Biology, 33(5): 693–702. May 2010.\n 00019\n\n\n\n
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\n\n\n@article{torp_snow-induced_2010,\n\ttitle = {Snow-induced changes in dwarf birch chemistry increase moth larval growth rate and level of herbivory},\n\tvolume = {33},\n\tissn = {0722-4060},\n\tdoi = {10.1007/s00300-009-0744-9},\n\tabstract = {Changes in snow cover might influence arctic ecosystems to the same extent as increased temperatures. Although the duration of snow cover is generally expected to decrease in the future as a result of global warming, the amounts of snow might increase in arctic areas where much of the elevated precipitation will fall as snow. We examined the effects of an increased snow cover, as a result of a snow fence treatment, on soil nitrogen mineralization, plant phenology, plant chemistry (nitrogen and potential defense compounds), the level of invertebrate herbivory, and performance of invertebrate herbivores in an arctic ecosystem, using dwarf birch (Betula nana) and the autumnal moth (Epirrita autumnata) as study organisms. An enhanced and prolonged snow cover increased the level of herbivory on dwarf birch leaves. Larvae feeding on plants that had experienced enhanced snow cover grew faster and pupated earlier than larvae fed with plant material from control plots, indicating that plants from enhanced snow-lie plots produce higher-quality food to herbivores. The increased larval growth rate was strongly correlated with higher leaf nitrogen concentration in plants subjected to snow manipulation, and also to certain phenolic acids. Snow manipulation did not change net nitrogen mineralization rates in the soil or total carbon concentration in leaves, but it altered the within-season fluctuating pattern of leaf phenolic compounds. This study demonstrates a positive relationship between increased snow cover and level of herbivory on deciduous shrubs, thus proposing a negative feedback on the climate-induced dwarf shrub expansion in arctic areas.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Polar Biology},\n\tauthor = {Torp, Mikaela and Olofsson, Johan and Witzell, Johanna and Baxter, Robert},\n\tmonth = may,\n\tyear = {2010},\n\tnote = {00019},\n\tkeywords = {\\#nosource, Betula nana, Epirrita autumnata, Nitrogen, Plant phenology, arctic tundra, climate change, climate-change, epirrita-autumnata, experimental manipulations, insect herbivores, mountain birch, nitrogen mineralization, northern alaska, phenolic-compounds, phenological asynchrony, snow fence},\n\tpages = {693--702},\n}\n\n\n\n\n\n Changes in snow cover might influence arctic ecosystems to the same extent as increased temperatures. Although the duration of snow cover is generally expected to decrease in the future as a result of global warming, the amounts of snow might increase in arctic areas where much of the elevated precipitation will fall as snow. We examined the effects of an increased snow cover, as a result of a snow fence treatment, on soil nitrogen mineralization, plant phenology, plant chemistry (nitrogen and potential defense compounds), the level of invertebrate herbivory, and performance of invertebrate herbivores in an arctic ecosystem, using dwarf birch (Betula nana) and the autumnal moth (Epirrita autumnata) as study organisms. An enhanced and prolonged snow cover increased the level of herbivory on dwarf birch leaves. Larvae feeding on plants that had experienced enhanced snow cover grew faster and pupated earlier than larvae fed with plant material from control plots, indicating that plants from enhanced snow-lie plots produce higher-quality food to herbivores. The increased larval growth rate was strongly correlated with higher leaf nitrogen concentration in plants subjected to snow manipulation, and also to certain phenolic acids. Snow manipulation did not change net nitrogen mineralization rates in the soil or total carbon concentration in leaves, but it altered the within-season fluctuating pattern of leaf phenolic compounds. This study demonstrates a positive relationship between increased snow cover and level of herbivory on deciduous shrubs, thus proposing a negative feedback on the climate-induced dwarf shrub expansion in arctic areas.\n
\n\n\n\n \n\n \n \n \n \n \n \n Compositional differentiation, vegetation-environment relationships and classification of willow-characterised vegetation in the western Eurasian Arctic.\n \n \n \n \n\n\n \n Pajunen, A.; Kaarlejärvi, E.; Forbes, B.; and Virtanen, R.\n\n\n \n\n\n\n Journal of Vegetation Science, 21(1): 107–119. February 2010.\n 00019\n\n\n\n
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\n\n\n@article{pajunen_compositional_2010,\n\ttitle = {Compositional differentiation, vegetation-environment relationships and classification of willow-characterised vegetation in the western {Eurasian} {Arctic}},\n\tvolume = {21},\n\tissn = {1654-1103},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1654-1103.2009.01123.x/abstract},\n\tdoi = {10.1111/j.1654-1103.2009.01123.x},\n\tabstract = {Question: How does willow-characterised tundra vegetation of western Eurasia vary, and what are the main vegetation types? What are the ecological gradients and climatic regimes underlying vegetation differentiation? Location: The dataset was collected across a wide spectrum of tundra habitats at 12 sites in subarctic and arctic areas spanning from NW Fennoscandia to West Siberia. Methods: The dataset, including 758 vegetation sample plots (relevés), was analysed using a TWINSPAN classification and NMDS ordination that also included analyses of vegetation-environment correlations. Results: Based on the TWINSPAN classification, eight vegetation types characterised by willow (cover of upright willows {\\textgreater}10\\%) were discerned: (1) Salix glauca-Carex aquatilis type, (2) Aulacomnium-Tomentypnum type, (3) Salix-Betula-Hylocomium type, (4) Salix lanata-Brachythecium mildeanum type, (5) Salix-Pachypleurum type, (6) S. lanata-Myosotis nemorosa type, (7) Salix-Trollius-Geranium type and (8) Salix-Comarum palustre-Filipendula ulmaria type. Willow-characterised vegetation types were compositionally differentiated from other tundra vegetation and were confined to relatively moist valley and sloping tundra sites, from mire to mineral soils. These vegetation types were encountered across a broad latitudinal zone in which July mean temperature ranged from 6 to 10°C. Conclusions: Willow-characterised tundra vegetation forms a broad category of ecologically and geographically differentiated vegetation types that are linked to dwarf shrub tundra, shrub tundra or mire. Because of complex ecological gradients underlying compositional differentiation, predicting the responses of willow-characterised tundra vegetation to a warming climate may be complicated.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-08},\n\tjournal = {Journal of Vegetation Science},\n\tauthor = {Pajunen, A.m. and Kaarlejärvi, E.m. and Forbes, B.c. and Virtanen, R.},\n\tmonth = feb,\n\tyear = {2010},\n\tnote = {00019},\n\tkeywords = {\\#nosource, Climatic gradient, NMDS ordination, Salix, TWINSPAN, tundra, vegetation pattern},\n\tpages = {107--119},\n}\n\n\n\n\n\n Question: How does willow-characterised tundra vegetation of western Eurasia vary, and what are the main vegetation types? What are the ecological gradients and climatic regimes underlying vegetation differentiation? Location: The dataset was collected across a wide spectrum of tundra habitats at 12 sites in subarctic and arctic areas spanning from NW Fennoscandia to West Siberia. Methods: The dataset, including 758 vegetation sample plots (relevés), was analysed using a TWINSPAN classification and NMDS ordination that also included analyses of vegetation-environment correlations. Results: Based on the TWINSPAN classification, eight vegetation types characterised by willow (cover of upright willows \\textgreater10%) were discerned: (1) Salix glauca-Carex aquatilis type, (2) Aulacomnium-Tomentypnum type, (3) Salix-Betula-Hylocomium type, (4) Salix lanata-Brachythecium mildeanum type, (5) Salix-Pachypleurum type, (6) S. lanata-Myosotis nemorosa type, (7) Salix-Trollius-Geranium type and (8) Salix-Comarum palustre-Filipendula ulmaria type. Willow-characterised vegetation types were compositionally differentiated from other tundra vegetation and were confined to relatively moist valley and sloping tundra sites, from mire to mineral soils. These vegetation types were encountered across a broad latitudinal zone in which July mean temperature ranged from 6 to 10°C. Conclusions: Willow-characterised tundra vegetation forms a broad category of ecologically and geographically differentiated vegetation types that are linked to dwarf shrub tundra, shrub tundra or mire. Because of complex ecological gradients underlying compositional differentiation, predicting the responses of willow-characterised tundra vegetation to a warming climate may be complicated.\n
\n\n\n\n \n\n \n \n \n \n \n \n Quantifying the relative importance of lake emissions in the carbon budget of a subarctic catchment.\n \n \n \n \n\n\n \n Karlsson, J.; Christensen, T. R.; Crill, P.; Förster, J.; Hammarlund, D.; Jackowicz-Korczynski, M.; Kokfelt, U.; Roehm, C.; and Rosén, P.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 115(G3): G03006. September 2010.\n 00037\n\n\n\n
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\n\n\n@article{karlsson_quantifying_2010,\n\ttitle = {Quantifying the relative importance of lake emissions in the carbon budget of a subarctic catchment},\n\tvolume = {115},\n\tissn = {2156-2202},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2010JG001305/abstract},\n\tdoi = {10.1029/2010JG001305},\n\tabstract = {Climate change and thawing of permafrost will likely result in increased decomposition of terrestrial organic carbon and subsequent carbon emissions to the atmosphere from terrestrial and aquatic systems. The quantitative importance of mineralization of terrestrial organic carbon in lakes in relation to terrestrial carbon fluxes is poorly understood and a serious drawback for the understanding of carbon budgets. We studied a subarctic lake in an area of discontinuous permafrost to assess the quantitative importance of lake carbon emission for the catchment carbon balance. Estimates of net ecosystem production and stable carbon-isotope composition of dissolved organic carbon in the lake water suggest substantial input and respiration of terrestrial organic carbon in the lake. The lake was a net source of CO2 and CH4 to the atmosphere at ice breakup in spring and during the whole ice-free period. The carbon emission from the lake was similar in magnitude to the terrestrial net release of carbon to the atmosphere. The results indicate that lakes are important sources of catchment carbon emission, potentially increasing the positive feedback from permafrost thawing on global warming.},\n\tlanguage = {en},\n\tnumber = {G3},\n\turldate = {2017-02-06},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Karlsson, Jan and Christensen, Torben R. and Crill, Patrick and Förster, Johannes and Hammarlund, Dan and Jackowicz-Korczynski, Marcin and Kokfelt, Ulla and Roehm, Charlotte and Rosén, Peter},\n\tmonth = sep,\n\tyear = {2010},\n\tnote = {00037},\n\tkeywords = {\\#nosource, 0428 Carbon cycling, 0458 Limnology, 0475 Permafrost, cryosphere, and high-latitude processes, 0490 Trace gases, Limnology, Permafrost, cryosphere, and high-latitude processes, Trace gases, carbon cycling, carbon emission, lake respiration, permafrost, subarctic lake, terrestrial organic carbon},\n\tpages = {G03006},\n}\n\n\n\n\n\n Climate change and thawing of permafrost will likely result in increased decomposition of terrestrial organic carbon and subsequent carbon emissions to the atmosphere from terrestrial and aquatic systems. The quantitative importance of mineralization of terrestrial organic carbon in lakes in relation to terrestrial carbon fluxes is poorly understood and a serious drawback for the understanding of carbon budgets. We studied a subarctic lake in an area of discontinuous permafrost to assess the quantitative importance of lake carbon emission for the catchment carbon balance. Estimates of net ecosystem production and stable carbon-isotope composition of dissolved organic carbon in the lake water suggest substantial input and respiration of terrestrial organic carbon in the lake. The lake was a net source of CO2 and CH4 to the atmosphere at ice breakup in spring and during the whole ice-free period. The carbon emission from the lake was similar in magnitude to the terrestrial net release of carbon to the atmosphere. The results indicate that lakes are important sources of catchment carbon emission, potentially increasing the positive feedback from permafrost thawing on global warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Turning northern peatlands upside down: disentangling microclimate and substrate quality effects on vertical distribution of Collembola.\n \n \n \n \n\n\n \n Krab, E. J.; Oorsprong, H.; Berg, M. P.; and Cornelissen, J. H.\n\n\n \n\n\n\n Functional Ecology, 24(6): 1362–1369. December 2010.\n \n\n\n\n
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\n\n\n@article{krab_turning_2010,\n\ttitle = {Turning northern peatlands upside down: disentangling microclimate and substrate quality effects on vertical distribution of {Collembola}},\n\tvolume = {24},\n\tissn = {1365-2435},\n\tshorttitle = {Turning northern peatlands upside down},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2010.01754.x/abstract},\n\tdoi = {10.1111/j.1365-2435.2010.01754.x},\n\tabstract = {1. Although direct contributions of soil invertebrates to carbon turnover are modest, they have a disproportionally large indirect impact through their control over the activity of microbial decomposers. Shifts in soil invertebrate species distribution might have a substantial effect on the decomposition process because their functional role depends on the species’ vertical position in soils. Gradients in microclimate and substrate quality and structure largely determine the vertical position of soil invertebrates. Because of the possible impact of climate change on soil invertebrate distribution, and consequently on decomposition, it is important to know the relative contributions of microclimate and substrate quality to the vertical distribution patterns of soil invertebrates. 2. We studied this for springtails (Collembola) as a keystone group in cool and cold biomes, by turning peat cores in a subarctic blanket bog upside down, thereby reversing the substrate quality gradient and leaving temperature and moisture gradients intact. 3. Two opposing groups of springtail species could be distinguished with respect to their abundance responses along the vertical gradient: (i) species that remain associated with the stratum they were originally found in (‘stayers’) and (ii) species that re-establish the original stratification pattern, by remigration either to the top or deeper layers, irrespective of any substrate quality change (‘movers’). Within the ‘mover’ response pattern, the direction of their migration in response to microclimate changes seemed to coincide with their ecomorphological traits. 4. Our results not only demonstrate that springtail species differ in their responses to changes in climate or substrate quality; they also suggest that interspecific faunal trait variation may provide a useful tool to predict animal responses to climatic changes.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-08},\n\tjournal = {Functional Ecology},\n\tauthor = {Krab, Eveline J. and Oorsprong, Hilde and Berg, Matty P. and Cornelissen, Johannes H.C.},\n\tmonth = dec,\n\tyear = {2010},\n\tkeywords = {\\#nosource, Collembola, Decomposition, climate change, ecomorphological traits, soil microclimate, substrate quality, vertical stratification},\n\tpages = {1362--1369},\n}\n\n\n\n\n\n 1. Although direct contributions of soil invertebrates to carbon turnover are modest, they have a disproportionally large indirect impact through their control over the activity of microbial decomposers. Shifts in soil invertebrate species distribution might have a substantial effect on the decomposition process because their functional role depends on the species’ vertical position in soils. Gradients in microclimate and substrate quality and structure largely determine the vertical position of soil invertebrates. Because of the possible impact of climate change on soil invertebrate distribution, and consequently on decomposition, it is important to know the relative contributions of microclimate and substrate quality to the vertical distribution patterns of soil invertebrates. 2. We studied this for springtails (Collembola) as a keystone group in cool and cold biomes, by turning peat cores in a subarctic blanket bog upside down, thereby reversing the substrate quality gradient and leaving temperature and moisture gradients intact. 3. Two opposing groups of springtail species could be distinguished with respect to their abundance responses along the vertical gradient: (i) species that remain associated with the stratum they were originally found in (‘stayers’) and (ii) species that re-establish the original stratification pattern, by remigration either to the top or deeper layers, irrespective of any substrate quality change (‘movers’). Within the ‘mover’ response pattern, the direction of their migration in response to microclimate changes seemed to coincide with their ecomorphological traits. 4. Our results not only demonstrate that springtail species differ in their responses to changes in climate or substrate quality; they also suggest that interspecific faunal trait variation may provide a useful tool to predict animal responses to climatic changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dynamics of alpine plant litter decomposition in a changing climate.\n \n \n \n \n\n\n \n Gavazov, K. S.\n\n\n \n\n\n\n Plant and Soil, 337(1-2): 19–32. December 2010.\n \n\n\n\n
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\n\n\n@article{gavazov_dynamics_2010,\n\ttitle = {Dynamics of alpine plant litter decomposition in a changing climate},\n\tvolume = {337},\n\tissn = {0032-079X, 1573-5036},\n\turl = {http://link.springer.com/article/10.1007/s11104-010-0477-0},\n\tdoi = {10.1007/s11104-010-0477-0},\n\tabstract = {Climatic changes resulting from anthropogenic activities over the passed century are repeatedly reported to alter the functioning of pristine ecosystems worldwide, and especially those in cold biomes. Available literature on the process of plant leaf litter decomposition in the temperate Alpine zone is reviewed here, with emphasis on both direct and indirect effects of climate change phenomena on rates of litter decay. Weighing the impact of biotic and abiotic processes governing litter mass loss, it appears that an immediate intensification of decomposition rates due to temperature rise can be retarded by decreased soil moisture, insufficient snow cover insulation, and shrub expansion in the Alpine zone. This tentative conclusion, remains speculative unless empirically tested, but it has profound implications for understanding the biogeochemical cycling in the Alpine vegetation belt, and its potential role as a buffering mechanism to climate change.},\n\tlanguage = {en},\n\tnumber = {1-2},\n\turldate = {2017-02-13},\n\tjournal = {Plant and Soil},\n\tauthor = {Gavazov, Konstantin S.},\n\tmonth = dec,\n\tyear = {2010},\n\tkeywords = {\\#nosource, Alpine, Biogeochemistry, Climate change, Plant growth form, Plant litter, Snow, Soil fauna},\n\tpages = {19--32},\n}\n\n\n\n\n\n Climatic changes resulting from anthropogenic activities over the passed century are repeatedly reported to alter the functioning of pristine ecosystems worldwide, and especially those in cold biomes. Available literature on the process of plant leaf litter decomposition in the temperate Alpine zone is reviewed here, with emphasis on both direct and indirect effects of climate change phenomena on rates of litter decay. Weighing the impact of biotic and abiotic processes governing litter mass loss, it appears that an immediate intensification of decomposition rates due to temperature rise can be retarded by decreased soil moisture, insufficient snow cover insulation, and shrub expansion in the Alpine zone. This tentative conclusion, remains speculative unless empirically tested, but it has profound implications for understanding the biogeochemical cycling in the Alpine vegetation belt, and its potential role as a buffering mechanism to climate change.\n
\n\n\n\n \n\n \n \n \n \n \n Microbial responses to P addition in six South African forest soils.\n \n \n \n\n\n \n Esberg, C.; du Toit, B.; Olsson, R.; Ilstedt, U.; and Giesler, R.\n\n\n \n\n\n\n Plant and Soil, 329(1-2): 209–225. April 2010.\n \n\n\n\n
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\n\n\n@article{esberg_microbial_2010,\n\ttitle = {Microbial responses to {P} addition in six {South} {African} forest soils},\n\tvolume = {329},\n\tissn = {0032-079X},\n\tdoi = {10.1007/s11104-009-0146-3},\n\tabstract = {Forests growing on highly weathered soils are often phosphorus (P) limited and competition between geochemical and biological sinks affects their soil P dynamics. In an attempt to elucidate the factors controlling the relative importance of these two sinks, we investigated the relationship of between soil microbial growth kinetics and soil chemical properties following amendments with C, N and P in six South African forest soils. Microbial growth kinetics were determined from respiration curves derived from measurements of CO(2) effluxes from soil samples in laboratory incubations. We found that microbial growth rates after C + N additions were positively related to NaOH-extractable P and decreased with soil depth, whereas the lag time (the time between substrate addition and exponential growth) was negatively related to extractable P. However, the growth rate and lag time were unrelated to the soil's sorption properties or Al and Fe contents. Our results indicate that at least some of the NaOH-extractable inorganic P may be biologically available within a relatively short time (days to weeks) and might be more labile than previously thought. Our results also show that microbial utilization of C + N only seemed to be constrained by P in the deeper part of the soil profiles.},\n\tlanguage = {English},\n\tnumber = {1-2},\n\tjournal = {Plant and Soil},\n\tauthor = {Esberg, Camilla and du Toit, Ben and Olsson, Rickard and Ilstedt, Ulrik and Giesler, Reiner},\n\tmonth = apr,\n\tyear = {2010},\n\tkeywords = {\\#nosource, Hedley fractionation, Microbial bioassay, Microbial growth rate, Phosphorus availability, Soil respiration, Weathered soils, available phosphorus, boreal forests, cold-storage, extraction methods, humus layer, iron accumulation, laboratory incubations, organic phosphorus, phosphate sorption, tropical forest},\n\tpages = {209--225},\n}\n\n\n\n\n\n Forests growing on highly weathered soils are often phosphorus (P) limited and competition between geochemical and biological sinks affects their soil P dynamics. In an attempt to elucidate the factors controlling the relative importance of these two sinks, we investigated the relationship of between soil microbial growth kinetics and soil chemical properties following amendments with C, N and P in six South African forest soils. Microbial growth kinetics were determined from respiration curves derived from measurements of CO(2) effluxes from soil samples in laboratory incubations. We found that microbial growth rates after C + N additions were positively related to NaOH-extractable P and decreased with soil depth, whereas the lag time (the time between substrate addition and exponential growth) was negatively related to extractable P. However, the growth rate and lag time were unrelated to the soil's sorption properties or Al and Fe contents. Our results indicate that at least some of the NaOH-extractable inorganic P may be biologically available within a relatively short time (days to weeks) and might be more labile than previously thought. Our results also show that microbial utilization of C + N only seemed to be constrained by P in the deeper part of the soil profiles.\n
\n\n\n\n \n\n \n \n \n \n \n \n Significant effects of temperature on the reproductive output of the forest herb Anemone nemorosa L.\n \n \n \n \n\n\n \n De Frenne, P.; Graae, B. J.; Kolb, A.; Brunet, J.; Chabrerie, O.; Cousins, S. A. O.; Decocq, G.; Dhondt, R.; Diekmann, M.; Eriksson, O.; Heinken, T.; Hermy, M.; Jõgar, Ü.; Saguez, R.; Shevtsova, A.; Stanton, S.; Zindel, R.; Zobel, M.; and Verheyen, K.\n\n\n \n\n\n\n Forest Ecology and Management, 259(4): 809–817. February 2010.\n 00028\n\n\n\n
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\n\n\n@article{de_frenne_significant_2010,\n\ttitle = {Significant effects of temperature on the reproductive output of the forest herb {Anemone} nemorosa {L}.},\n\tvolume = {259},\n\tissn = {0378-1127},\n\turl = {http://www.sciencedirect.com/science/article/pii/S037811270900334X},\n\tdoi = {10.1016/j.foreco.2009.04.038},\n\tabstract = {Climate warming is already influencing plant migration in different parts of the world. Numerous models have been developed to forecast future plant distributions. Few studies, however, have investigated the potential effect of warming on the reproductive output of plants. Understorey forest herbs in particular, have received little attention in the debate on climate change impacts.\n\nThis study focuses on the effect of temperature on sexual reproductive output (number of seeds, seed mass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slow colonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 km latitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006 and 2008). This study design allowed us to isolate the effects of accumulated temperature (Growing Degree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seed sowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally, we disentangled correlations between the different reproductive traits of A. nemorosa along the latitudinal gradient.\n\nWe found a clear positive relationship between accumulated temperature and seed and seedling traits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient. Seed mass and seedling mass, for instance, increased by 9.7\\% and 10.4\\%, respectively, for every 1000 °C h increase in GDH. We also derived strong correlations between several seed and seedling traits both under field conditions and in incubators. Our results indicate that seed mass, incubator-based germination percentage (Germ\\%Inc) and the output of germinable seeds (product of number of seeds and Germ\\%Inc divided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes) provide valuable proxies to parameterize key population processes in models.\n\nWe conclude that (1) climate warming may have a pronounced positive impact on sexual reproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit from including the temperature sensitivity of key seed traits and population processes.},\n\tnumber = {4},\n\turldate = {2016-11-08},\n\tjournal = {Forest Ecology and Management},\n\tauthor = {De Frenne, P. and Graae, B. J. and Kolb, A. and Brunet, J. and Chabrerie, O. and Cousins, S. A. O. and Decocq, G. and Dhondt, R. and Diekmann, M. and Eriksson, O. and Heinken, T. and Hermy, M. and Jõgar, Ü. and Saguez, R. and Shevtsova, A. and Stanton, S. and Zindel, R. and Zobel, M. and Verheyen, K.},\n\tmonth = feb,\n\tyear = {2010},\n\tnote = {00028},\n\tkeywords = {\\#nosource, climate change, herbaceous forest species, latitudinal gradient, reproduction, seeds, temperature},\n\tpages = {809--817},\n}\n\n\n\n\n\n Climate warming is already influencing plant migration in different parts of the world. Numerous models have been developed to forecast future plant distributions. Few studies, however, have investigated the potential effect of warming on the reproductive output of plants. Understorey forest herbs in particular, have received little attention in the debate on climate change impacts. This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seed mass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slow colonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 km latitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006 and 2008). This study design allowed us to isolate the effects of accumulated temperature (Growing Degree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seed sowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally, we disentangled correlations between the different reproductive traits of A. nemorosa along the latitudinal gradient. We found a clear positive relationship between accumulated temperature and seed and seedling traits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient. Seed mass and seedling mass, for instance, increased by 9.7% and 10.4%, respectively, for every 1000 °C h increase in GDH. We also derived strong correlations between several seed and seedling traits both under field conditions and in incubators. Our results indicate that seed mass, incubator-based germination percentage (Germ%Inc) and the output of germinable seeds (product of number of seeds and Germ%Inc divided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes) provide valuable proxies to parameterize key population processes in models. We conclude that (1) climate warming may have a pronounced positive impact on sexual reproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit from including the temperature sensitivity of key seed traits and population processes.\n
\n\n\n\n \n\n \n \n \n \n \n The Effect of Snow on Plant Chemistry and Invertebrate Herbivory: Experimental Manipulations Along a Natural Snow Gradient.\n \n \n \n\n\n \n Torp, M.; Witzell, J.; Baxter, R.; and Olofsson, J.\n\n\n \n\n\n\n Ecosystems, 13(5): 741–751. August 2010.\n 00013\n\n\n\n
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\n\n\n@article{torp_effect_2010,\n\ttitle = {The {Effect} of {Snow} on {Plant} {Chemistry} and {Invertebrate} {Herbivory}: {Experimental} {Manipulations} {Along} a {Natural} {Snow} {Gradient}},\n\tvolume = {13},\n\tissn = {1432-9840},\n\tshorttitle = {The {Effect} of {Snow} on {Plant} {Chemistry} and {Invertebrate} {Herbivory}},\n\tdoi = {10.1007/s10021-010-9351-4},\n\tabstract = {Changing snow conditions have strong effects on northern ecosystems, but these effects are rarely incorporated into ecosystem models and our perception of how the ecosystems will respond to a warmer climate. We investigated the relationships between snow cover, plant phenology, level of invertebrate herbivory and leaf chemical traits in Betula nana in four different habitats located along a natural snow cover gradient. To separate the effect of snow per se from other differences, we manipulated the snow cover with snow fences in three habitats. The experimentally prolonged snow cover delayed plant phenology, but not as much as expected based on the pattern along the natural gradient. The positive effect of the snow treatment on plant nitrogen concentration was also weaker than expected, because plant nitrogen concentration closely followed plant phenology. The level of herbivory by leaf-chewing invertebrates increased in response to an increased snow cover, at least at the end of the growing season. The concentration of phenolic substances varied among habitats, treatments and sampling occasions, indicating that B. nana shrubs were able to retain a mosaic of secondary chemical quality despite altered snow conditions. This study shows that the effect of the snow cover period on leaf nitrogen concentration and level of herbivory can be predicted based on differences between habitats, whereas the effect of a changed plant phenology on plant nitrogen concentration is better explained by temporal trends within habitats. These results have important implications for how northern ecosystems should respond to future climate changes.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Ecosystems},\n\tauthor = {Torp, Mikaela and Witzell, Johanna and Baxter, Robert and Olofsson, Johan},\n\tmonth = aug,\n\tyear = {2010},\n\tnote = {00013},\n\tkeywords = {\\#nosource, Betula nana, Ecosystems, Nitrogen, climate-change, environmental-change, experimental manipulation, forage, herbivory, natural gradient, northern sweden, phenolic-compounds, phenolics, phenology, responses, snow, svalbard reindeer, tundra, vegetation},\n\tpages = {741--751},\n}\n\n\n\n\n\n Changing snow conditions have strong effects on northern ecosystems, but these effects are rarely incorporated into ecosystem models and our perception of how the ecosystems will respond to a warmer climate. We investigated the relationships between snow cover, plant phenology, level of invertebrate herbivory and leaf chemical traits in Betula nana in four different habitats located along a natural snow cover gradient. To separate the effect of snow per se from other differences, we manipulated the snow cover with snow fences in three habitats. The experimentally prolonged snow cover delayed plant phenology, but not as much as expected based on the pattern along the natural gradient. The positive effect of the snow treatment on plant nitrogen concentration was also weaker than expected, because plant nitrogen concentration closely followed plant phenology. The level of herbivory by leaf-chewing invertebrates increased in response to an increased snow cover, at least at the end of the growing season. The concentration of phenolic substances varied among habitats, treatments and sampling occasions, indicating that B. nana shrubs were able to retain a mosaic of secondary chemical quality despite altered snow conditions. This study shows that the effect of the snow cover period on leaf nitrogen concentration and level of herbivory can be predicted based on differences between habitats, whereas the effect of a changed plant phenology on plant nitrogen concentration is better explained by temporal trends within habitats. These results have important implications for how northern ecosystems should respond to future climate changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Temperature-controlled organic carbon mineralization in lake sediments.\n \n \n \n \n\n\n \n Gudasz, C.; Bastviken, D.; Steger, K.; Premke, K.; Sobek, S.; and Tranvik, L. J.\n\n\n \n\n\n\n Nature, 466(7305): 478–481. July 2010.\n Number: 7305 Publisher: Nature Publishing Group\n\n\n\n
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\n\n\n@article{gudasz_temperature-controlled_2010,\n\ttitle = {Temperature-controlled organic carbon mineralization in lake sediments},\n\tvolume = {466},\n\tissn = {1476-4687},\n\turl = {http://www.nature.com/articles/nature09186},\n\tdoi = {10.1038/nature09186},\n\tabstract = {Inland water sediments are important, but commonly disregarded long-term carbon sinks — in fact, the annual burial of organic carbon in lakes and reservoirs exceeds that of ocean sediments. Gudasz et al. now show that for several different types of lake in subarctic Sweden, the mineralization of carbon in lake sediments significantly increases as temperatures increase. Assuming that future organic carbon delivery to the lake sediments will be similar to present-day conditions, this could act as a positive feedback to global warming.},\n\tlanguage = {en},\n\tnumber = {7305},\n\turldate = {2020-08-31},\n\tjournal = {Nature},\n\tauthor = {Gudasz, Cristian and Bastviken, David and Steger, Kristin and Premke, Katrin and Sobek, Sebastian and Tranvik, Lars J.},\n\tmonth = jul,\n\tyear = {2010},\n\tnote = {Number: 7305\nPublisher: Nature Publishing Group},\n\tkeywords = {\\#nosource},\n\tpages = {478--481},\n}\n\n\n\n\n\n Inland water sediments are important, but commonly disregarded long-term carbon sinks — in fact, the annual burial of organic carbon in lakes and reservoirs exceeds that of ocean sediments. Gudasz et al. now show that for several different types of lake in subarctic Sweden, the mineralization of carbon in lake sediments significantly increases as temperatures increase. Assuming that future organic carbon delivery to the lake sediments will be similar to present-day conditions, this could act as a positive feedback to global warming.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stable isotope analysis of benthic fauna and their food sources in boreal lakes.\n \n \n \n \n\n\n \n Premke, K.; Karlsson, J.; Steger, K.; Gudasz, C.; von Wachenfeldt, E.; and Tranvik, L. J.\n\n\n \n\n\n\n Journal of the North American Benthological Society, 29(4): 1339–1348. December 2010.\n Publisher: The University of Chicago Press\n\n\n\n
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\n\n\n@article{premke_stable_2010,\n\ttitle = {Stable isotope analysis of benthic fauna and their food sources in boreal lakes},\n\tvolume = {29},\n\tissn = {0887-3593},\n\turl = {https://www.journals.uchicago.edu/doi/abs/10.1899/10-002.1},\n\tdoi = {10.1899/10-002.1},\n\tabstract = {The origin of organic C supporting zoobenthic communities in 8 boreal lakes with different concentrations of dissolved organic C (DOC) was assessed by stable-isotope analysis. Profundal zoobenthos was depleted in 13C compared to littoral zoobenthos, and this difference increased with decreasing DOC concentration. The δ13C of littoral zoobenthos suggested reliance on benthic algae, whereas depleted 13C of profundal zoobenthos could be explained by contributions from allochthonous and autochthonous C sources. In deeper lakes, profundal zoobenthos diets also included C processed by methanotrophic bacteria. Littoral zoobenthos δ13C decreased with increasing DOC concentration in the lake water. Our results suggest that littoral benthic fauna are mainly supported by benthic algae in low-DOC lakes and by phytoplankton and allochthonous organic C in high-DOC lakes and that this difference is a result of light absorbance and energy supply by allochthonous organic C. Increasing allochthonous DOC inputs, as expected in a warmer and wetter climate, might reduce benthic algal production and alter the organic C base for benthic food webs in lake ecosystems.},\n\tnumber = {4},\n\turldate = {2020-08-31},\n\tjournal = {Journal of the North American Benthological Society},\n\tauthor = {Premke, Katrin and Karlsson, Jan and Steger, Kristin and Gudasz, Cristian and von Wachenfeldt, Eddie and Tranvik, Lars J.},\n\tmonth = dec,\n\tyear = {2010},\n\tnote = {Publisher: The University of Chicago Press},\n\tkeywords = {\\#nosource},\n\tpages = {1339--1348},\n}\n\n\n\n\n\n The origin of organic C supporting zoobenthic communities in 8 boreal lakes with different concentrations of dissolved organic C (DOC) was assessed by stable-isotope analysis. Profundal zoobenthos was depleted in 13C compared to littoral zoobenthos, and this difference increased with decreasing DOC concentration. The δ13C of littoral zoobenthos suggested reliance on benthic algae, whereas depleted 13C of profundal zoobenthos could be explained by contributions from allochthonous and autochthonous C sources. In deeper lakes, profundal zoobenthos diets also included C processed by methanotrophic bacteria. Littoral zoobenthos δ13C decreased with increasing DOC concentration in the lake water. Our results suggest that littoral benthic fauna are mainly supported by benthic algae in low-DOC lakes and by phytoplankton and allochthonous organic C in high-DOC lakes and that this difference is a result of light absorbance and energy supply by allochthonous organic C. Increasing allochthonous DOC inputs, as expected in a warmer and wetter climate, might reduce benthic algal production and alter the organic C base for benthic food webs in lake ecosystems.\n
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\n \n \n\n \n \n \n \n \n Soil phosphorus and microbial response to a long-term wildfire chronosequence in northern Sweden.\n \n \n \n\n\n \n Lagerström, A.; Esberg, C.; Wardle, D. A.; and Giesler, R.\n\n\n \n\n\n\n Biogeochemistry, 95(2-3): 199–213. September 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{lagerstrom_soil_2009,\n\ttitle = {Soil phosphorus and microbial response to a long-term wildfire chronosequence in northern {Sweden}},\n\tvolume = {95},\n\tissn = {0168-2563},\n\tdoi = {10.1007/s10533-009-9331-y},\n\tabstract = {In the prolonged absence of major disturbances, ecosystems may enter a stage of retrogression, which is characterized by decreased ecosystem process rates both above and belowground, and often reduced availability of phosphorus (P). Disturbance through wildfire can increase soil P losses through leaching or erosion, but in the long-term absence of fire, soil P could potentially become increasingly bound in more stable forms that are less available to microbes. We studied forms of P and microbial respiration kinetics in the humus layer of a group of islands that vary considerably in wildfire frequency (40-5,300 years since last fire), and which are known to enter retrogression in the prolonged absence of fire. We found a decrease in labile P with decreasing fire frequency but no change in total P. Soil microorganisms responded more strongly to N than to P addition, and microbial biomass N:P ratios remained unchanged across the gradient. However, the concentration of labile P was the best predictor of microbial respiration responses across the islands, and this provides some evidence that declining access to P could contribute to the decline in soil microbial activity during retrogression. Our results show that even though N is arguably the main limiting nutrient during retrogression in this chronosequence, long term absence of fire also causes a decline in P availability which negatively affects microbial activity. This in turn could potentially impair microbially driven processes such as decomposition and mineralization and further contribute to the reduced availability of soil nutrients during retrogression.},\n\tlanguage = {English},\n\tnumber = {2-3},\n\tjournal = {Biogeochemistry},\n\tauthor = {Lagerström, Anna and Esberg, Camilla and Wardle, David A. and Giesler, Reiner},\n\tmonth = sep,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Boreal forest, Microbial respiration, Nitrogen, Retrogression, Succession, Wild fire, biomass, boreal forests, ecosystem properties, island area, new-zealand, nutrient limitation, organic soil, phosphorus, rain-forest, respiration},\n\tpages = {199--213},\n}\n\n\n\n\n\n In the prolonged absence of major disturbances, ecosystems may enter a stage of retrogression, which is characterized by decreased ecosystem process rates both above and belowground, and often reduced availability of phosphorus (P). Disturbance through wildfire can increase soil P losses through leaching or erosion, but in the long-term absence of fire, soil P could potentially become increasingly bound in more stable forms that are less available to microbes. We studied forms of P and microbial respiration kinetics in the humus layer of a group of islands that vary considerably in wildfire frequency (40-5,300 years since last fire), and which are known to enter retrogression in the prolonged absence of fire. We found a decrease in labile P with decreasing fire frequency but no change in total P. Soil microorganisms responded more strongly to N than to P addition, and microbial biomass N:P ratios remained unchanged across the gradient. However, the concentration of labile P was the best predictor of microbial respiration responses across the islands, and this provides some evidence that declining access to P could contribute to the decline in soil microbial activity during retrogression. Our results show that even though N is arguably the main limiting nutrient during retrogression in this chronosequence, long term absence of fire also causes a decline in P availability which negatively affects microbial activity. This in turn could potentially impair microbially driven processes such as decomposition and mineralization and further contribute to the reduced availability of soil nutrients during retrogression.\n
\n\n\n\n \n\n \n \n \n \n \n Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis.\n \n \n \n\n\n \n Lyon, S. W.; Destouni, G.; Giesler, R.; Humborg, C.; Morth, M.; Seibert, J.; Karlsson, J.; and Troch, P. A.\n\n\n \n\n\n\n Hydrology and Earth System Sciences, 13(5): 595–604. 2009.\n \n\n\n\n
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\n\n\n@article{lyon_estimation_2009,\n\ttitle = {Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis},\n\tvolume = {13},\n\tissn = {1027-5606},\n\tdoi = {10.5194/hess-13-595-2009},\n\tabstract = {Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Hydrology and Earth System Sciences},\n\tauthor = {Lyon, S. W. and Destouni, G. and Giesler, R. and Humborg, C. and Morth, M. and Seibert, J. and Karlsson, J. and Troch, P. A.},\n\tyear = {2009},\n\tkeywords = {\\#nosource, abisko, alaska, basin, drainage, hydrology, northern sweden, regions, river discharge, runoff generation, siberia},\n\tpages = {595--604},\n}\n\n\n\n\n\n Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.\n
\n\n\n\n \n\n \n \n \n \n \n \n Production and emission of CO2 in two unproductive lakes in northern Sweden.\n \n \n \n \n\n\n \n Åberg, J.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2009.\n Publisher: Institutionen för Ekologi, miljö och geovetenskap, Umeå universitet\n\n\n\n
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\n\n\n@phdthesis{aberg_production_2009,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Production and emission of {CO2} in two unproductive lakes in northern {Sweden}},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-26967},\n\tabstract = {Unproductive lakes are one of few natural landscape compartments with net release of carbon to the atmosphere. Lakes also generally decrease the net terrestrial carbon uptake, since most of the CO2 ...},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Åberg, Jan},\n\tcollaborator = {Jansson, Mats and Jonsson, Anders},\n\tyear = {2009},\n\tnote = {Publisher: Institutionen för Ekologi, miljö och geovetenskap, Umeå universitet},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n Unproductive lakes are one of few natural landscape compartments with net release of carbon to the atmosphere. Lakes also generally decrease the net terrestrial carbon uptake, since most of the CO2 ...\n
\n\n\n\n \n\n \n \n \n \n \n \n A feather hydrogen isoscape for Mexico.\n \n \n \n \n\n\n \n Hobson, K. A.; Van Wilgenburg, S. L.; Larson, K. W.; and Wassenaar, L. I.\n\n\n \n\n\n\n Journal of Geochemical Exploration, 102(3): 167–174. 2009.\n 00022\n\n\n\n
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\n\n\n@article{hobson_feather_2009,\n\ttitle = {A feather hydrogen isoscape for {Mexico}},\n\tvolume = {102},\n\tissn = {0375-6742},\n\turl = {http://www.science-direct.com/science/article/B6VCP-4WR5NMC-1/2/b6cd5dc8640040e686b8c58fe9f73c4f},\n\tdoi = {10.1016/j.gexplo.2009.02.007},\n\tabstract = {Developing useful biological isoscapes for areas of the world is a priority. This is the case for Mexico that hosts a large percentage of North America's Neotropical migrant birds. Here we investigated the use of House Sparrow (Passer domesticus) feathers to create a spatially explicit feather deuterium isoscape for that country using samples (n = 461) that were collected across Mexico. Considerable and useful spatial hydrogen isotopic structure was observed, suggesting that isotopes may be a potential forensic tool for evaluating origins of Mexican derived fauna and flora. The most positive feather [delta]D values occurred in the northeast and most negative in the south-central part of the country, roughly matching [delta]D patterns observed in groundwater. A weak negative isotopic relationship was found with altitude in both the Pacific and Atlantic drainage systems. The most parsimonious model describing isotopic spatial variation in feathers between 300 and 3000 m a.s.l. included groundwater [delta]D ([delta]Dgw; precipitation proxy), sex, amount of precipitation, and the coefficient of variation in amount of precipitation. Overall, [delta]Dgw was a poor predictor of sparrow [delta]Df values for all of Mexico. However, this relationship was considerably strengthened when we considered sex separately, removed the Baja peninsula from our sample, and considered the Atlantic and Pacific drainage basins separately. The strongest relationship between [delta]Dgw and [delta]Df was found for female sparrows in the Atlantic drainage basin (r2 = 0.464). We recommend that researchers interested in inferring origins of migratory birds and other animals in Mexico create species specific isotopic basemaps that may be guided by the isotopic patterns we have observed for House Sparrows and groundwater.},\n\tnumber = {3},\n\turldate = {2009-08-11},\n\tjournal = {Journal of Geochemical Exploration},\n\tauthor = {Hobson, Keith A. and Van Wilgenburg, Steven L. and Larson, Keith W. and Wassenaar, Leonard I.},\n\tyear = {2009},\n\tnote = {00022},\n\tkeywords = {\\#nosource, Deuterium, Feather, House Sparrow, Isoscape, Mexico, groundwater},\n\tpages = {167--174},\n}\n\n\n\n\n\n Developing useful biological isoscapes for areas of the world is a priority. This is the case for Mexico that hosts a large percentage of North America's Neotropical migrant birds. Here we investigated the use of House Sparrow (Passer domesticus) feathers to create a spatially explicit feather deuterium isoscape for that country using samples (n = 461) that were collected across Mexico. Considerable and useful spatial hydrogen isotopic structure was observed, suggesting that isotopes may be a potential forensic tool for evaluating origins of Mexican derived fauna and flora. The most positive feather [delta]D values occurred in the northeast and most negative in the south-central part of the country, roughly matching [delta]D patterns observed in groundwater. A weak negative isotopic relationship was found with altitude in both the Pacific and Atlantic drainage systems. The most parsimonious model describing isotopic spatial variation in feathers between 300 and 3000 m a.s.l. included groundwater [delta]D ([delta]Dgw; precipitation proxy), sex, amount of precipitation, and the coefficient of variation in amount of precipitation. Overall, [delta]Dgw was a poor predictor of sparrow [delta]Df values for all of Mexico. However, this relationship was considerably strengthened when we considered sex separately, removed the Baja peninsula from our sample, and considered the Atlantic and Pacific drainage basins separately. The strongest relationship between [delta]Dgw and [delta]Df was found for female sparrows in the Atlantic drainage basin (r2 = 0.464). We recommend that researchers interested in inferring origins of migratory birds and other animals in Mexico create species specific isotopic basemaps that may be guided by the isotopic patterns we have observed for House Sparrows and groundwater.\n
\n\n\n\n \n\n \n \n \n \n \n \n A groundwater isoscape (δD, δ18O) for Mexico.\n \n \n \n \n\n\n \n Wassenaar, L.; Van Wilgenburg, S.; Larson, K. W.; and Hobson, K.\n\n\n \n\n\n\n Journal of Geochemical Exploration, 102(3): 123–136. 2009.\n 00072\n\n\n\n
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\n\n\n@article{wassenaar_groundwater_2009,\n\ttitle = {A groundwater isoscape (δ{D}, δ{18O}) for {Mexico}},\n\tvolume = {102},\n\tissn = {0375-6742},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0375674209000107},\n\tdoi = {10.1016/j.gexplo.2009.01.001},\n\tabstract = {Numerous studies have shown that precipitation isocapes drive δD and δ18O patterns in surficial waters and in terrestrial food webs. While the GNIP (Global Network for Isotopes in Precipitation) dataset provided a key foundation for linking precipitation-terrestrial isoscapes globally, it has insufficient spatial coverage in many countries like Mexico. To overcome this limitation, we hypothesized that shallow phreatic groundwaters in Mexico could be used as an isotopic integrator of long-term seasonally weighted precipitation inputs to the landscape to aid in calibrating spatial H and O isotope datasets for terrestrial, biological and hydrological research. Groundwater was sampled from 234 sites in Mexico at {\\textasciitilde}\\&\\#xa0;50 km latitudinal spacing to obtain high spatial resolution and country-wide coverage for the construction of a groundwater isoscape. Our data revealed that shallow groundwater infiltration in Mexico appears largely unaffected by evaporation and reflects seasonally weighted precipitation inputs. These precipitation inputs are primarily biased to summertime when highest rainfall occurs, but a small degree of post-precipitation evaporation revealed a lower d-excess zone that corresponded to the interior semi-arid ecozone. We developed a predictive general linear model (GLM) for hydrogen and oxygen isotopic spatial patterns in Mexican groundwater and then compared the results to a validation subset of our field data, as well external data reported in the literature. The GLM used elevation, latitude, drainage basin (Atlantic vs. Pacific), and rainfall as the most relevant predictive variables. The GLM explained 81\\% of the overall isotopic variance observed in groundwater, 68\\% of the variance within our validation subset, and 77\\% of the variance in the external data set. Our predictive GLM is sufficiently accurate to allow for future ecological, hydrological and forensic isoscape applications in Mexico, and may be an approach that is applicable to other countries and regions where GNIP stations are lacking.},\n\tnumber = {3},\n\turldate = {2012-05-12},\n\tjournal = {Journal of Geochemical Exploration},\n\tauthor = {Wassenaar, L.I. and Van Wilgenburg, S.L. and Larson, K. W. and Hobson, K.A.},\n\tyear = {2009},\n\tnote = {00072},\n\tkeywords = {\\#nosource, Deuterium, Isoscapes, Isotopes, Mexico, Oxygen-18, groundwater, precipitation},\n\tpages = {123--136},\n}\n\n\n\n\n\n Numerous studies have shown that precipitation isocapes drive δD and δ18O patterns in surficial waters and in terrestrial food webs. While the GNIP (Global Network for Isotopes in Precipitation) dataset provided a key foundation for linking precipitation-terrestrial isoscapes globally, it has insufficient spatial coverage in many countries like Mexico. To overcome this limitation, we hypothesized that shallow phreatic groundwaters in Mexico could be used as an isotopic integrator of long-term seasonally weighted precipitation inputs to the landscape to aid in calibrating spatial H and O isotope datasets for terrestrial, biological and hydrological research. Groundwater was sampled from 234 sites in Mexico at ~ 50 km latitudinal spacing to obtain high spatial resolution and country-wide coverage for the construction of a groundwater isoscape. Our data revealed that shallow groundwater infiltration in Mexico appears largely unaffected by evaporation and reflects seasonally weighted precipitation inputs. These precipitation inputs are primarily biased to summertime when highest rainfall occurs, but a small degree of post-precipitation evaporation revealed a lower d-excess zone that corresponded to the interior semi-arid ecozone. We developed a predictive general linear model (GLM) for hydrogen and oxygen isotopic spatial patterns in Mexican groundwater and then compared the results to a validation subset of our field data, as well external data reported in the literature. The GLM used elevation, latitude, drainage basin (Atlantic vs. Pacific), and rainfall as the most relevant predictive variables. The GLM explained 81% of the overall isotopic variance observed in groundwater, 68% of the variance within our validation subset, and 77% of the variance in the external data set. Our predictive GLM is sufficiently accurate to allow for future ecological, hydrological and forensic isoscape applications in Mexico, and may be an approach that is applicable to other countries and regions where GNIP stations are lacking.\n
\n\n\n\n \n\n \n \n \n \n \n \n Taxonomic Implications of Morphological Variation in Cercis canadensis (Fabaceae) from Mexico and Adjacent Parts of Texas.\n \n \n \n \n\n\n \n Fritsch, P. W.; Schiller, A. M.; and Larson, K. W.\n\n\n \n\n\n\n Systematic Botany, 34(3): 510–520. 2009.\n 00014\n\n\n\n
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\n\n\n\n@article{fritsch_taxonomic_2009,\n\ttitle = {Taxonomic {Implications} of {Morphological} {Variation} in {Cercis} canadensis ({Fabaceae}) from {Mexico} and {Adjacent} {Parts} of {Texas}},\n\tvolume = {34},\n\tissn = {0363-6445},\n\turl = {http://www.bioone.org.ludwig.lub.lu.se/doi/abs/10.1600/036364409789271254},\n\tdoi = {10.1600/036364409789271254},\n\tnumber = {3},\n\tjournal = {Systematic Botany},\n\tauthor = {Fritsch, Peter W. and Schiller, Anja M. and Larson, Keith W.},\n\tyear = {2009},\n\tnote = {00014},\n\tkeywords = {\\#nosource},\n\tpages = {510--520},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Critical periods for impact of climate warming on early seedling establishment in subarctic tundra.\n \n \n \n \n\n\n \n Shevtsova, A.; Graae, B. J.; Jochum, T.; Milbau, A.; Kockelbergh, F.; Beyens, L.; and Nijs, I.\n\n\n \n\n\n\n Global Change Biology, 15(11): 2662–2680. November 2009.\n 00056\n\n\n\n
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\n\n\n@article{shevtsova_critical_2009,\n\ttitle = {Critical periods for impact of climate warming on early seedling establishment in subarctic tundra},\n\tvolume = {15},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1365-2486.2009.01947.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2009.01947.x},\n\tabstract = {Climate warming is expected to shift bioclimatic zones and plant species distribution. Yet, few studies have explored whether seedling establishment is a possible bottleneck for future migration and population resilience. We test how warming affects the early stages of seedling establishment in 10 plant species in subarctic tundra. To zoom into the life phases where the effects of warming actually take place, we used a novel approach of breaking down the whole-season warming effect into full factorial combination of early-, mid-, and late-season warming periods. Seeds were sown in containers placed under field conditions in subarctic heath and were exposed to 3 °C elevation of surface temperature and 30\\% addition of summer precipitation relative to ambient. Heating was achieved with Free Air Temperature Increase systems. Whole-season heating reduced germination and establishment, significantly in four out of 10 species. The whole-season warming effect originated from additive effects of individual periods, although some of the periods had disproportionally stronger influence. Early-germinating species were susceptible to warming; the critical phases were early summer for germination and mid summer for seedling survival. Graminoids, which emerged later, were less susceptible although some negative effects during late summer were observed. Some species with intermediate germination time were affected by all periods of warming. Addition of water generally could not mitigate the negative effects of whole-season heating, but at individual species level both strengthening and amelioration of these negative effects were observed. We conclude that summer warming is likely to constrain seedling recruitment in open micro sites, which is a common seed regeneration niche in tundra ecosystem. Importantly, we described both significant temporal and species-specific variation in the sensitivity of seedling establishment to warming which needs to be taken into consideration when modelling population dynamics and vegetation transitions in a warmer climate.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2016-11-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Shevtsova, Anna and Graae, Bente Jessen and Jochum, Till and Milbau, Ann and Kockelbergh, Fred and Beyens, Louis and Nijs, Ivan},\n\tmonth = nov,\n\tyear = {2009},\n\tnote = {00056},\n\tkeywords = {\\#nosource, Arctic, FATI, climate change, median germination time, mortality, precipitation, recruitment, regeneration from seedlings, seed germination, seedling establishment},\n\tpages = {2662--2680},\n}\n\n\n\n\n\n Climate warming is expected to shift bioclimatic zones and plant species distribution. Yet, few studies have explored whether seedling establishment is a possible bottleneck for future migration and population resilience. We test how warming affects the early stages of seedling establishment in 10 plant species in subarctic tundra. To zoom into the life phases where the effects of warming actually take place, we used a novel approach of breaking down the whole-season warming effect into full factorial combination of early-, mid-, and late-season warming periods. Seeds were sown in containers placed under field conditions in subarctic heath and were exposed to 3 °C elevation of surface temperature and 30% addition of summer precipitation relative to ambient. Heating was achieved with Free Air Temperature Increase systems. Whole-season heating reduced germination and establishment, significantly in four out of 10 species. The whole-season warming effect originated from additive effects of individual periods, although some of the periods had disproportionally stronger influence. Early-germinating species were susceptible to warming; the critical phases were early summer for germination and mid summer for seedling survival. Graminoids, which emerged later, were less susceptible although some negative effects during late summer were observed. Some species with intermediate germination time were affected by all periods of warming. Addition of water generally could not mitigate the negative effects of whole-season heating, but at individual species level both strengthening and amelioration of these negative effects were observed. We conclude that summer warming is likely to constrain seedling recruitment in open micro sites, which is a common seed regeneration niche in tundra ecosystem. Importantly, we described both significant temporal and species-specific variation in the sensitivity of seedling establishment to warming which needs to be taken into consideration when modelling population dynamics and vegetation transitions in a warmer climate.\n
\n\n\n\n \n\n \n \n \n \n \n Comparison between chironomid-inferred July temperatures and meteorological data AD 1850-2001 from varved Lake Silvaplana, Switzerland.\n \n \n \n\n\n \n Larocque, I.; Grosjean, M.; Heiri, O.; Bigler, C.; and Blass, A.\n\n\n \n\n\n\n Journal of Paleolimnology, 41(2): 329–342. February 2009.\n 00051\n\n\n\n
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\n\n\n@article{larocque_comparison_2009,\n\ttitle = {Comparison between chironomid-inferred {July} temperatures and meteorological data {AD} 1850-2001 from varved {Lake} {Silvaplana}, {Switzerland}},\n\tvolume = {41},\n\tissn = {0921-2728},\n\tdoi = {10.1007/s10933-008-9228-0},\n\tabstract = {Inferred temperatures from chironomids preserved in the varved sediment of Lake Silvaplana in the Eastern Swiss Alps were compared with instrumental data obtained from a meteorological station in Sils-Maria, on the shore of Lake Silvaplana, for the time interval 1850-2001. At near-annual resolution, the general patterns of chironomid-inferred temperature changes followed the meteorological record over the last 150 years (r (Pearson) = 0.65, P = 0.01) and 87\\% of the inferences had deviations from the instrumental data below the root-mean-square error of prediction (RMSEP). When the inferences were compared with a 2-year running mean in the meteorological data, 94\\% of the inferences had differences with the instrumental data below the RMSEP, indicating that more than half of the inaccurate inferences may have been due to errors in varve counting. Larger deviations from the instrumental data were also obtained from samples with low percentages of fossil taxa represented in the training set used for temperature reconstruction and/or assemblages with poor fit to temperature. Changes in total phosphorus (TP, as inferred by diatoms) and/or greater precipitation were possible factors affecting the accuracy of the temperature reconstruction. Although these factors might affect the quantitative estimates, obtaining {\\textgreater} 80\\% accurate temperature inferences suggests that chironomid analysis is a reliable tool for reconstructing mean July air temperature quantitatively over the last 150 years in Lake Silvaplana.},\n\tlanguage = {English},\n\tnumber = {2},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Larocque, Isabelle and Grosjean, Martin and Heiri, Oliver and Bigler, Christian and Blass, Alex},\n\tmonth = feb,\n\tyear = {2009},\n\tnote = {00051},\n\tkeywords = {\\#nosource, Dating errors, Holocene, Non-biting midges, Numerical methods, Reconstruction, air temperatures, alpine lake, climate change, european alps, fossil midges, meteorological data, mountain lakes, northern sweden, quantitative indicators, swiss alps},\n\tpages = {329--342},\n}\n\n\n\n\n\n Inferred temperatures from chironomids preserved in the varved sediment of Lake Silvaplana in the Eastern Swiss Alps were compared with instrumental data obtained from a meteorological station in Sils-Maria, on the shore of Lake Silvaplana, for the time interval 1850-2001. At near-annual resolution, the general patterns of chironomid-inferred temperature changes followed the meteorological record over the last 150 years (r (Pearson) = 0.65, P = 0.01) and 87% of the inferences had deviations from the instrumental data below the root-mean-square error of prediction (RMSEP). When the inferences were compared with a 2-year running mean in the meteorological data, 94% of the inferences had differences with the instrumental data below the RMSEP, indicating that more than half of the inaccurate inferences may have been due to errors in varve counting. Larger deviations from the instrumental data were also obtained from samples with low percentages of fossil taxa represented in the training set used for temperature reconstruction and/or assemblages with poor fit to temperature. Changes in total phosphorus (TP, as inferred by diatoms) and/or greater precipitation were possible factors affecting the accuracy of the temperature reconstruction. Although these factors might affect the quantitative estimates, obtaining \\textgreater 80% accurate temperature inferences suggests that chironomid analysis is a reliable tool for reconstructing mean July air temperature quantitatively over the last 150 years in Lake Silvaplana.\n
\n\n\n\n \n\n \n \n \n \n \n Spatial and temporal patterns of greenness on the Yamal Peninsula, Russia: interactions of ecological and social factors affecting the Arctic normalized difference vegetation index.\n \n \n \n\n\n \n Walker, D. A.; Leibman, M. O.; Epstein, H. E.; Forbes, B. C.; Bhatt, U. S.; Raynolds, M. K.; Comiso, J. C.; Gubarkov, A. A.; Khomutov, A. V.; Jia, G. J.; Kaarlejarvi, E.; Kaplan, J. O.; Kumpula, T.; Kuss, P.; Matyshak, G.; Moskalenko, N. G.; Orekhov, P.; Romanovsky, V. E.; Ukraientseva, N. G.; and Yu, Q.\n\n\n \n\n\n\n Environmental Research Letters, 4(4): 045004. December 2009.\n 00057\n\n\n\n
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\n\n\n@article{walker_spatial_2009,\n\ttitle = {Spatial and temporal patterns of greenness on the {Yamal} {Peninsula}, {Russia}: interactions of ecological and social factors affecting the {Arctic} normalized difference vegetation index},\n\tvolume = {4},\n\tissn = {1748-9326},\n\tshorttitle = {Spatial and temporal patterns of greenness on the {Yamal} {Peninsula}, {Russia}},\n\tdoi = {10.1088/1748-9326/4/4/045004},\n\tabstract = {The causes of a greening trend detected in the Arctic using the normalized difference vegetation index (NDVI) are still poorly understood. Changes in NDVI are a result of multiple ecological and social factors that affect tundra net primary productivity. Here we use a 25 year time series of AVHRR-derived NDVI data (AVHRR: advanced very high resolution radiometer), climate analysis, a global geographic information database and ground-based studies to examine the spatial and temporal patterns of vegetation greenness on the Yamal Peninsula, Russia. We assess the effects of climate change, gas-field development, reindeer grazing and permafrost degradation. In contrast to the case for Arctic North America, there has not been a significant trend in summer temperature or NDVI, and much of the pattern of NDVI in this region is due to disturbances. There has been a 37\\% change in early-summer coastal sea-ice concentration, a 4\\% increase in summer land temperatures and a 7\\% change in the average time-integrated NDVI over the length of the satellite observations. Gas-field infrastructure is not currently extensive enough to affect regional NDVI patterns. The effect of reindeer is difficult to quantitatively assess because of the lack of control areas where reindeer are excluded. Many of the greenest landscapes on the Yamal are associated with landslides and drainage networks that have resulted from ongoing rapid permafrost degradation. A warming climate and enhanced winter snow are likely to exacerbate positive feedbacks between climate and permafrost thawing. We present a diagram that summarizes the social and ecological factors that influence Arctic NDVI. The NDVI should be viewed as a powerful monitoring tool that integrates the cumulative effect of a multitude of factors affecting Arctic land-cover change.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Environmental Research Letters},\n\tauthor = {Walker, D. A. and Leibman, M. O. and Epstein, H. E. and Forbes, B. C. and Bhatt, U. S. and Raynolds, M. K. and Comiso, J. C. and Gubarkov, A. A. and Khomutov, A. V. and Jia, G. J. and Kaarlejarvi, E. and Kaplan, J. O. and Kumpula, T. and Kuss, P. and Matyshak, G. and Moskalenko, N. G. and Orekhov, P. and Romanovsky, V. E. and Ukraientseva, N. G. and Yu, Q.},\n\tmonth = dec,\n\tyear = {2009},\n\tnote = {00057},\n\tkeywords = {\\#nosource, Bovanenkovo, Ecosystems, Nentsy, Plants, climate, climate change, disturbance, dynamics, gas development, history, infrastructure, ndvi, northern alaska, reindeer herding, responses, temperature, tundra},\n\tpages = {045004},\n}\n\n\n\n\n\n The causes of a greening trend detected in the Arctic using the normalized difference vegetation index (NDVI) are still poorly understood. Changes in NDVI are a result of multiple ecological and social factors that affect tundra net primary productivity. Here we use a 25 year time series of AVHRR-derived NDVI data (AVHRR: advanced very high resolution radiometer), climate analysis, a global geographic information database and ground-based studies to examine the spatial and temporal patterns of vegetation greenness on the Yamal Peninsula, Russia. We assess the effects of climate change, gas-field development, reindeer grazing and permafrost degradation. In contrast to the case for Arctic North America, there has not been a significant trend in summer temperature or NDVI, and much of the pattern of NDVI in this region is due to disturbances. There has been a 37% change in early-summer coastal sea-ice concentration, a 4% increase in summer land temperatures and a 7% change in the average time-integrated NDVI over the length of the satellite observations. Gas-field infrastructure is not currently extensive enough to affect regional NDVI patterns. The effect of reindeer is difficult to quantitatively assess because of the lack of control areas where reindeer are excluded. Many of the greenest landscapes on the Yamal are associated with landslides and drainage networks that have resulted from ongoing rapid permafrost degradation. A warming climate and enhanced winter snow are likely to exacerbate positive feedbacks between climate and permafrost thawing. We present a diagram that summarizes the social and ecological factors that influence Arctic NDVI. The NDVI should be viewed as a powerful monitoring tool that integrates the cumulative effect of a multitude of factors affecting Arctic land-cover change.\n
\n\n\n\n \n\n \n \n \n \n \n Complementary UV protective compounds in zooplankton.\n \n \n \n\n\n \n Hylander, S.; Boeing, W. J.; Graneli, W.; Karlsson, J.; von Einem, J.; Gutseit, K.; and Hansson, L.\n\n\n \n\n\n\n Limnology and Oceanography, 54(6): 1883–1893. November 2009.\n 00036\n\n\n\n
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\n\n\n@article{hylander_complementary_2009,\n\ttitle = {Complementary {UV} protective compounds in zooplankton},\n\tvolume = {54},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2009.54.6.1883},\n\tabstract = {Zooplankton accumulate several groups of photoprotective compounds to shield against damaging ultraviolet radiation (UV). One of these groups, the carotenoids, makes the animals more conspicuous to visually hunting predators, whereas others, such as the mycosporine-like amino acids (MAAs) may not. The blend of photoprotective compounds is therefore important for the UV defense but also for the ability to escape predation through crypsis. Here we assess laboratory and field data from different latitudes to examine how UV, predation threat, and pigment availability ( in food) affects the mixture of UV-protective compounds in copepods. Overall, the blend of MAAs and carotenoids was partly explained by the availability of MAAs in the food, the UV-threat, and the presence of predators. Copepods upregulated their MAA content when UV threat was increasing (i.e., if MAAs were abundant in food), and in field data this accumulation only occurred at high levels of predation threat. If MAAs were scarce, copepods instead compensated with higher carotenoid accumulation. However, when there was a high predation threat this carotenoid compensatory effect was disadvantageous, and low concentrations of both MAAs and carotenoids at high UV-threat resulted in lower reproduction. In all, these results showed that carotenoids and MAAs are complementary substances, i.e., one is high when the other is low, and copepods are, hence, able to adjust their blend of different UV-protective compounds to optimize their defenses to the threats of UV and predation. These defense systems may buffer against direct food-web interactions and help the zooplankton to survive in environments with high UV threat.},\n\tlanguage = {English},\n\tnumber = {6},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Hylander, Samuel and Boeing, Wiebke J. and Graneli, Wilhelm and Karlsson, Jan and von Einem, Jessica and Gutseit, Kelly and Hansson, Lars-Anders},\n\tmonth = nov,\n\tyear = {2009},\n\tnote = {00036},\n\tkeywords = {\\#nosource, adaptive significance, amino-acids maas, dissolved organic-carbon, fresh-water copepod, phenotypic plasticity, photoprotective compounds, planktonic organisms, trade-off, trait compensation, ultraviolet-radiation},\n\tpages = {1883--1893},\n}\n\n\n\n\n\n Zooplankton accumulate several groups of photoprotective compounds to shield against damaging ultraviolet radiation (UV). One of these groups, the carotenoids, makes the animals more conspicuous to visually hunting predators, whereas others, such as the mycosporine-like amino acids (MAAs) may not. The blend of photoprotective compounds is therefore important for the UV defense but also for the ability to escape predation through crypsis. Here we assess laboratory and field data from different latitudes to examine how UV, predation threat, and pigment availability ( in food) affects the mixture of UV-protective compounds in copepods. Overall, the blend of MAAs and carotenoids was partly explained by the availability of MAAs in the food, the UV-threat, and the presence of predators. Copepods upregulated their MAA content when UV threat was increasing (i.e., if MAAs were abundant in food), and in field data this accumulation only occurred at high levels of predation threat. If MAAs were scarce, copepods instead compensated with higher carotenoid accumulation. However, when there was a high predation threat this carotenoid compensatory effect was disadvantageous, and low concentrations of both MAAs and carotenoids at high UV-threat resulted in lower reproduction. In all, these results showed that carotenoids and MAAs are complementary substances, i.e., one is high when the other is low, and copepods are, hence, able to adjust their blend of different UV-protective compounds to optimize their defenses to the threats of UV and predation. These defense systems may buffer against direct food-web interactions and help the zooplankton to survive in environments with high UV threat.\n
\n\n\n\n \n\n \n \n \n \n \n Landscape variations in stream water SO42- and delta S-34(SO4) in a boreal stream network.\n \n \n \n\n\n \n Bjorkvald, L.; Giesler, R.; Laudon, H.; Humborg, C.; and Morth, C.\n\n\n \n\n\n\n Geochimica Et Cosmochimica Acta, 73(16): 4648–4660. August 2009.\n 00000\n\n\n\n
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\n\n\n@article{bjorkvald_landscape_2009,\n\ttitle = {Landscape variations in stream water {SO42}- and delta {S}-34({SO4}) in a boreal stream network},\n\tvolume = {73},\n\tissn = {0016-7037},\n\tdoi = {10.1016/j.gca.2009.05.052},\n\tabstract = {Despite reduced anthropogenic deposition during the last decades, deposition sulphate may still play an important role in the biogeochemical cycles of S and many catchments may act as net sources of S that may remain for several decades. The aim of this study is to elucidate the temporal and spatial dynamics of both SO42- and delta S-34(SO4) in stream water from catchments with varying percentage of wetland and forest coverage and to determine their relative importance for catchment losses of S. Stream water samples were collected from 15 subcatchments ranging in size from 3 to 6780 ha, in a boreal stream network, northern Sweden. In forested catchments ({\\textless}2\\% wetland cover) S-SO42- concentrations in stream water averaged 1.7 mg L-1 whereas in wetland dominated catchments ({\\textgreater}30\\% wetland cover) the concentrations averaged 0.3 mg L-1. A significant negative relationship was observed between S-SO42- and percentage wetland coverage (r(2) = 0.77, p {\\textless} 0.001) and the annual export of stream water SO42- and wetland coverage (r(2) = 0.76 p {\\textless} 0.001). The percentage forest coverage was on the other hand positively related to stream water SO42- concentrations and the annual export of stream water SO42- (r(2) = 0.77 and r(2) = 0.79, respectively). The annual average delta S-34(SO4) value in wetland dominated streams was +7.6\\%omicron. and in streams of forested catchments +6.7\\%omicron. At spring flood the delta S-34(SO4) values decreased in all streams by 1\\%omicron to 5\\%omicron. The delta S-34(SO4) values in all streams were higher than the delta S-34(SO4) value of +4.7\\%omicron in precipitation (snow). The export of S ranged from 0.5 kg S ha(-1) yr(-1) (wetland headwater stream) to 3.8 kg S ha(-1) yr(-1) (forested headwater stream). With an average S deposition in open field of 1.3 kg S ha(-1) yr(-1) (2002-2006) the mass balance results in a net export of S from all catchments, except in catchments with {\\textgreater}30\\% wetland. The high temporal and spatial resolution of this study demonstrates that the reducing environments of wetlands play a key role for the biogeochemistry of S in boreal landscapes and are net sinks of S. Forested areas, on the other hand were net sources of S. (C) 2009 Elsevier Ltd. All rights reserved.},\n\tlanguage = {English},\n\tnumber = {16},\n\tjournal = {Geochimica Et Cosmochimica Acta},\n\tauthor = {Bjorkvald, Louise and Giesler, Reiner and Laudon, Hjalmar and Humborg, Christoph and Morth, Carl-Magnus},\n\tmonth = aug,\n\tyear = {2009},\n\tnote = {00000},\n\tkeywords = {\\#nosource, atmospheric deposition, brook experimental forest, hubbard-brook, long-term, northern sweden, oxygen-isotope ratios, s-isotope, south-central ontario, sulfate deposition, sulfur dynamics},\n\tpages = {4648--4660},\n}\n\n\n\n\n\n Despite reduced anthropogenic deposition during the last decades, deposition sulphate may still play an important role in the biogeochemical cycles of S and many catchments may act as net sources of S that may remain for several decades. The aim of this study is to elucidate the temporal and spatial dynamics of both SO42- and delta S-34(SO4) in stream water from catchments with varying percentage of wetland and forest coverage and to determine their relative importance for catchment losses of S. Stream water samples were collected from 15 subcatchments ranging in size from 3 to 6780 ha, in a boreal stream network, northern Sweden. In forested catchments (\\textless2% wetland cover) S-SO42- concentrations in stream water averaged 1.7 mg L-1 whereas in wetland dominated catchments (\\textgreater30% wetland cover) the concentrations averaged 0.3 mg L-1. A significant negative relationship was observed between S-SO42- and percentage wetland coverage (r(2) = 0.77, p \\textless 0.001) and the annual export of stream water SO42- and wetland coverage (r(2) = 0.76 p \\textless 0.001). The percentage forest coverage was on the other hand positively related to stream water SO42- concentrations and the annual export of stream water SO42- (r(2) = 0.77 and r(2) = 0.79, respectively). The annual average delta S-34(SO4) value in wetland dominated streams was +7.6%omicron. and in streams of forested catchments +6.7%omicron. At spring flood the delta S-34(SO4) values decreased in all streams by 1%omicron to 5%omicron. The delta S-34(SO4) values in all streams were higher than the delta S-34(SO4) value of +4.7%omicron in precipitation (snow). The export of S ranged from 0.5 kg S ha(-1) yr(-1) (wetland headwater stream) to 3.8 kg S ha(-1) yr(-1) (forested headwater stream). With an average S deposition in open field of 1.3 kg S ha(-1) yr(-1) (2002-2006) the mass balance results in a net export of S from all catchments, except in catchments with \\textgreater30% wetland. The high temporal and spatial resolution of this study demonstrates that the reducing environments of wetlands play a key role for the biogeochemistry of S in boreal landscapes and are net sinks of S. Forested areas, on the other hand were net sources of S. (C) 2009 Elsevier Ltd. All rights reserved.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Winter Distribution of the Western Gull-billed Tern (Gelochelidon nilotica vanrossemi).\n \n \n \n \n\n\n \n Molina, K. C.; Garrett, K. L.; Larson, K. W.; and Craig, D. P.\n\n\n \n\n\n\n Western Birds, 40(1): 2–20. 2009.\n 00000\n\n\n\n
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\n\n\n@article{molina_winter_2009,\n\ttitle = {The {Winter} {Distribution} of the {Western} {Gull}-billed {Tern} ({Gelochelidon} nilotica vanrossemi)},\n\tvolume = {40},\n\tissn = {0160-1121},\n\turl = {http://dx.doi.org/10.1675/1524-4695(2006)29[271:TDACSO]2.0.CO;2},\n\tdoi = {10.1675/1524-4695(2006)29[271:TDACSO]2.0.CO;2},\n\tabstract = {We surveyed 73 sites along the Gulf of California and Pacific coasts of mainland Mexico during five nonbreeding seasons from December 1999 to January 2007 to clarify the winter status and distribution of the western North American subspecies of the Gull-billed Tern (Gelochelidon nilotica vanrossemi), a taxon of conservation concern. We located birds at 44 of the 73 sites, (60\\%) with the largest numbers found around coastal lagoons with extensive tidal flats in southern Sonora, Sinaloa, and extreme northern Nayarit. Local concentrations were also noted at other sites from the Colorado River delta of extreme northwestern Sonora south to Guerrero. Resightings of birds banded as chicks at California breeding colonies establish the first evidence of connectivity to specific wintering sites in Mexico as far south as southern Sonora and possibly into Nayarit.\n\nThe Gull-billed Tern (Gelochelidon nilotica) is widespread in temperate, subtropical, and tropical regions of the Old and New Worlds, but many populations, particularly those in North America, appear to be declining (Parnell et al. 1995, Molina and Erwin 2006). The western North American subspecies (G. n. vanrossemi, the Western Gull-billed Tern) of southern California and western Mexico breeds at few known colonies, and its seasonal movements are poorly understood. The limited range and low population size of this subspecies (about 250 breeding pairs in the United States and perhaps as few as 600 pairs throughout its range in western Mexico; Molina and Erwin 2006, Palacios and Mellink 2007) has led to its listing as a species of special concern in California (Remsen 1978, Molina 2008) and a national bird of conservation concern (USDI 2002).\n\nGull-billed Terns are less dependent on marine and other aquatic habitats than are many other species of terns, and they commonly forage over a variety of terrestrial habitats. Their broad diet includes a variety of insects, marine invertebrates, reptiles, amphibians, small fish, and the small chicks of birds; as opportunistic feeders they often exploit ephemerally abundant populations of prey such as crickets and weevils (Molina 2008). These terns frequently forage singly or in groups of two or three individuals (Molina and Marschalek 2003). Nearly all of our knowledge of Gull-billed Tern ecology results from studies conducted during the breeding season (Parnell et al. 1995). Conservation efforts directed toward migratory species, however, require an understanding of distribution and ecology throughout the year (Coulter and Frederick 1997, Kushlan et al. 2002, Martin et al. 2007).\n\nThe winter range of the Western Gull-billed Tern has been outlined in the literature only in general terms (Howell and Webb 1995, Parnell et al. 1995), with some treatments (e.g., Hellmayr and Conover 1948, American Ornithologists' Union 1957) suggesting this subspecies winters south to Ecuador. Breeding populations in California (Salton Sea and south San Diego Bay) withdraw southward (Patten et al. 2003, Unitt 2004, Molina and Erwin 2006). Although Molina and Erwin (2006) presented more detail on winter distribution and included a brief analysis of the limited Christmas Bird Count (CBC) data available from Mexico, the extent of the subspecies' winter range in Mexico and the areas and habitats supporting important concentrations have not been described. Here we report on the results of surveys for Gull-billed Terns in western Mexico conducted during five winters between 1999 and 2007. Our objectives are to determine geographical areas and habitats of importance to this subspecies during the winter period and, secondarily, to link California-breeding Gull-billed Terns to specific sites used in the nonbreeding season. We also review other published and unpublished information on the winter range of vanrossemi to amplify our survey results.},\n\tnumber = {1},\n\tjournal = {Western Birds},\n\tauthor = {Molina, Kathy C. and Garrett, Kimball L. and Larson, Keith W. and Craig, David P.},\n\tyear = {2009},\n\tnote = {00000},\n\tkeywords = {\\#nosource},\n\tpages = {2--20},\n}\n\n\n\n\n\n We surveyed 73 sites along the Gulf of California and Pacific coasts of mainland Mexico during five nonbreeding seasons from December 1999 to January 2007 to clarify the winter status and distribution of the western North American subspecies of the Gull-billed Tern (Gelochelidon nilotica vanrossemi), a taxon of conservation concern. We located birds at 44 of the 73 sites, (60%) with the largest numbers found around coastal lagoons with extensive tidal flats in southern Sonora, Sinaloa, and extreme northern Nayarit. Local concentrations were also noted at other sites from the Colorado River delta of extreme northwestern Sonora south to Guerrero. Resightings of birds banded as chicks at California breeding colonies establish the first evidence of connectivity to specific wintering sites in Mexico as far south as southern Sonora and possibly into Nayarit. The Gull-billed Tern (Gelochelidon nilotica) is widespread in temperate, subtropical, and tropical regions of the Old and New Worlds, but many populations, particularly those in North America, appear to be declining (Parnell et al. 1995, Molina and Erwin 2006). The western North American subspecies (G. n. vanrossemi, the Western Gull-billed Tern) of southern California and western Mexico breeds at few known colonies, and its seasonal movements are poorly understood. The limited range and low population size of this subspecies (about 250 breeding pairs in the United States and perhaps as few as 600 pairs throughout its range in western Mexico; Molina and Erwin 2006, Palacios and Mellink 2007) has led to its listing as a species of special concern in California (Remsen 1978, Molina 2008) and a national bird of conservation concern (USDI 2002). Gull-billed Terns are less dependent on marine and other aquatic habitats than are many other species of terns, and they commonly forage over a variety of terrestrial habitats. Their broad diet includes a variety of insects, marine invertebrates, reptiles, amphibians, small fish, and the small chicks of birds; as opportunistic feeders they often exploit ephemerally abundant populations of prey such as crickets and weevils (Molina 2008). These terns frequently forage singly or in groups of two or three individuals (Molina and Marschalek 2003). Nearly all of our knowledge of Gull-billed Tern ecology results from studies conducted during the breeding season (Parnell et al. 1995). Conservation efforts directed toward migratory species, however, require an understanding of distribution and ecology throughout the year (Coulter and Frederick 1997, Kushlan et al. 2002, Martin et al. 2007). The winter range of the Western Gull-billed Tern has been outlined in the literature only in general terms (Howell and Webb 1995, Parnell et al. 1995), with some treatments (e.g., Hellmayr and Conover 1948, American Ornithologists' Union 1957) suggesting this subspecies winters south to Ecuador. Breeding populations in California (Salton Sea and south San Diego Bay) withdraw southward (Patten et al. 2003, Unitt 2004, Molina and Erwin 2006). Although Molina and Erwin (2006) presented more detail on winter distribution and included a brief analysis of the limited Christmas Bird Count (CBC) data available from Mexico, the extent of the subspecies' winter range in Mexico and the areas and habitats supporting important concentrations have not been described. Here we report on the results of surveys for Gull-billed Terns in western Mexico conducted during five winters between 1999 and 2007. Our objectives are to determine geographical areas and habitats of importance to this subspecies during the winter period and, secondarily, to link California-breeding Gull-billed Terns to specific sites used in the nonbreeding season. We also review other published and unpublished information on the winter range of vanrossemi to amplify our survey results.\n
\n\n\n\n \n\n \n \n \n \n \n \n Spatial and Seasonal Variations in Stream Water δ34S-Dissolved Organic Matter in Northern Sweden.\n \n \n \n \n\n\n \n Giesler, R.; Björkvald, L.; Laudon, H.; and Mörth, C.\n\n\n \n\n\n\n Environmental Science & Technology, 43(2): 447–452. January 2009.\n 00006\n\n\n\n
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\n\n\n@article{giesler_spatial_2009,\n\ttitle = {Spatial and {Seasonal} {Variations} in {Stream} {Water} δ{34S}-{Dissolved} {Organic} {Matter} in {Northern} {Sweden}},\n\tvolume = {43},\n\tissn = {0013-936X},\n\turl = {http://dx.doi.org/10.1021/es8017946},\n\tdoi = {10.1021/es8017946},\n\tabstract = {The discharge of terrestrial dissolved organic matter (DOM) by streams is an important cross-system linkage that strongly influences downstream aquatic ecosystems. Isotopic tracers are important tools that can help to unravel the source of DOM from different terrestrial compartments in the landscape. Here we demonstrate the spatial and seasonal variation of δ34S of DOM in 10 boreal streams to test if the tracer could provide new insights into the origin of DOM. We found large spatial and seasonal variations in stream water δ34S-DOM values ranging from −5.2‰ to +9.6‰ with an average of +4.0 ± 0.6 (N = 62; average and 95\\% confidence interval). Large seasonal variations were found in stream water δ34S-DOM values: for example, a shift of more than 10‰ during the spring snowmelt in a wetland-dominated stream. Spatial differences were also observed during the winter base flow with higher δ34S-DOM values in the fourth-order Krycklan stream at the outlet of the 68 km2 catchment compared to the small ({\\textless}1 km2) headwater streams. Our data clearly show that the δ34S-DOM values have the potential to be used as a tracer to identify and generate new insights about terrestrial DOM sources in the boreal landscape.},\n\tnumber = {2},\n\turldate = {2017-02-07},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Giesler, Reiner and Björkvald, Louise and Laudon, Hjalmar and Mörth, Carl-Magnus},\n\tmonth = jan,\n\tyear = {2009},\n\tnote = {00006},\n\tkeywords = {\\#nosource, Sphagnum, carbon, catchments, chemistry, delta-c-13, deposition, forest soils, isotope fractionation, stable sulfur, sulfate},\n\tpages = {447--452},\n}\n\n\n\n\n\n The discharge of terrestrial dissolved organic matter (DOM) by streams is an important cross-system linkage that strongly influences downstream aquatic ecosystems. Isotopic tracers are important tools that can help to unravel the source of DOM from different terrestrial compartments in the landscape. Here we demonstrate the spatial and seasonal variation of δ34S of DOM in 10 boreal streams to test if the tracer could provide new insights into the origin of DOM. We found large spatial and seasonal variations in stream water δ34S-DOM values ranging from −5.2‰ to +9.6‰ with an average of +4.0 ± 0.6 (N = 62; average and 95% confidence interval). Large seasonal variations were found in stream water δ34S-DOM values: for example, a shift of more than 10‰ during the spring snowmelt in a wetland-dominated stream. Spatial differences were also observed during the winter base flow with higher δ34S-DOM values in the fourth-order Krycklan stream at the outlet of the 68 km2 catchment compared to the small (\\textless1 km2) headwater streams. Our data clearly show that the δ34S-DOM values have the potential to be used as a tracer to identify and generate new insights about terrestrial DOM sources in the boreal landscape.\n
\n\n\n\n \n\n \n \n \n \n \n Effects of climate on organic carbon and the ratio of planktonic to benthic primary producers in a subarctic lake during the past 45 years.\n \n \n \n\n\n \n Rosén, P.; Cunningham, L.; Vonk, J. E.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 54(5): 1723–1732. September 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{rosen_effects_2009,\n\ttitle = {Effects of climate on organic carbon and the ratio of planktonic to benthic primary producers in a subarctic lake during the past 45 years},\n\tvolume = {54},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2009.54.5.1723},\n\tabstract = {The effects of climatic variables on lake-water total organic carbon (TOC) concentrations and benthic and pelagic primary producers during the past 45 yr were assessed using the sediment records of two subarctic lakes, one with mires and one without mires connected to the lake. The lake with a mire showed large and synchronous changes in the planktonic to benthic (P : B) ratio of diatoms and concentrations of TOC inferred from near-infrared spectroscopy. During periods of warm temperatures, high precipitation, and long ice-free conditions, we inferred high TOC in the lake, and the diatom community was dominated by planktonic species. The stable carbon isotopic (delta C-13) values of sediment organic matter were negatively correlated with inferred TOC concentration and P : B ratio. We suggest that the changes in TOC and P : B ratio were a result of changing climate, permafrost degradation, and related changes in the catchment. Terrestrial organic matter, by its strong effect on the penetration of light through the lake water, possibly affected the habitats available for benthic photosynthesis and thus the delta C-13 of the sediment organic matter. The large changes in recent times may also be because of unusually long ice-free periods, warmer temperatures, and other associated limnological changes. The lake with no mire next to the lake showed only minor changes in lake-water TOC during the same period and P : B ratio remained almost constant until the past 5 yr, when the P : B ratio increased rapidly. The observed changes in P : B ratio within this lake may be because of complex interactions of several climate-related variables.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Rosén, Peter and Cunningham, Laura and Vonk, Jorien E. and Karlsson, Jan},\n\tmonth = sep,\n\tyear = {2009},\n\tkeywords = {\\#nosource, american, dioxide supersaturation, environmental-changes, exposure, gradient, near-infrared spectroscopy, northern sweden, permafrost, respiration, waters},\n\tpages = {1723--1732},\n}\n\n\n\n\n\n The effects of climatic variables on lake-water total organic carbon (TOC) concentrations and benthic and pelagic primary producers during the past 45 yr were assessed using the sediment records of two subarctic lakes, one with mires and one without mires connected to the lake. The lake with a mire showed large and synchronous changes in the planktonic to benthic (P : B) ratio of diatoms and concentrations of TOC inferred from near-infrared spectroscopy. During periods of warm temperatures, high precipitation, and long ice-free conditions, we inferred high TOC in the lake, and the diatom community was dominated by planktonic species. The stable carbon isotopic (delta C-13) values of sediment organic matter were negatively correlated with inferred TOC concentration and P : B ratio. We suggest that the changes in TOC and P : B ratio were a result of changing climate, permafrost degradation, and related changes in the catchment. Terrestrial organic matter, by its strong effect on the penetration of light through the lake water, possibly affected the habitats available for benthic photosynthesis and thus the delta C-13 of the sediment organic matter. The large changes in recent times may also be because of unusually long ice-free periods, warmer temperatures, and other associated limnological changes. The lake with no mire next to the lake showed only minor changes in lake-water TOC during the same period and P : B ratio remained almost constant until the past 5 yr, when the P : B ratio increased rapidly. The observed changes in P : B ratio within this lake may be because of complex interactions of several climate-related variables.\n
\n\n\n\n \n\n \n \n \n \n \n \n Ecosystem responses to increased precipitation and permafrost decay in subarctic Sweden inferred from peat and lake sediments.\n \n \n \n \n\n\n \n Kokfelt, U.; Rosén, P.; Schoning, K.; Christensen, T. R.; Förster, J.; Karlsson, J.; Reuss, N.; Rundgren, M.; Callaghan, T. V.; Jonasson, C.; and Hammarlund, D.\n\n\n \n\n\n\n Global Change Biology, 15(7): 1652–1663. July 2009.\n 00051\n\n\n\n
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\n\n\n@article{kokfelt_ecosystem_2009,\n\ttitle = {Ecosystem responses to increased precipitation and permafrost decay in subarctic {Sweden} inferred from peat and lake sediments},\n\tvolume = {15},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.01880.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2009.01880.x},\n\tabstract = {Recent accelerated decay of discontinuous permafrost at the Stordalen Mire in northern Sweden has been attributed to increased temperature and snow depth, and has caused expansion of wet minerotrophic areas leading to significant changes in carbon cycling in the mire. In order to track these changes through time and evaluate potential forcing mechanisms, this paper analyses a peat succession and a lake sediment sequence from within the mire, providing a record for the last 100 years, and compares these with monitored climate and active layer thickness data. The peat core was analysed for testate amoebae to reconstruct changes in peatland surface moisture conditions and water table fluctuations. The lake sediment core was analysed by near infrared spectroscopy to infer changes in the total organic carbon (TOC) concentration of the lake-water, and changes in δ13C and C, N and δ15N to track changes in the dissolved inorganic carbon (DIC) pool and the influence of diagenetic effects on sediment organic matter, respectively. Results showed that major shifts towards increased peat surface moisture and TOC concentration of the lake-water occurred around 1980, one to two decades earlier than a temperature driven increase in active layer thickness. Comparison with monitored temperature and precipitation from a nearby climate station indicates that this change in peat surface moisture is related to June–September (JJAS) precipitation and that the increase in lake-water TOC concentration reflects an increase in total annual precipitation. A significant depletion in 13C of sediment organic matter in the early 1980s probably reflects the effect of a single or a few consecutive years with anomalously high summer precipitation, resulting in elevated DIC content of the lake water, predominantly originating from increased export and subsequent respiration of organic carbon from the mire. Based on these results, it was not possible to link proxy data obtained on peat and lake-sediment records directly to permafrost decay. Instead our data indicate that increased precipitation and anomalously high rainfall during summers had a significant impact on the mire and the adjacent lake ecosystem. We therefore propose that effects of increased precipitation should be considered when evaluating potential forcing mechanisms of recent changes in carbon cycling in the subarctic.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-06},\n\tjournal = {Global Change Biology},\n\tauthor = {Kokfelt, U. and Rosén, P. and Schoning, K. and Christensen, T. R. and Förster, J. and Karlsson, J. and Reuss, N. and Rundgren, M. and Callaghan, T. V. and Jonasson, C. and Hammarlund, D.},\n\tmonth = jul,\n\tyear = {2009},\n\tnote = {00051},\n\tkeywords = {\\#nosource, TOC, carbon cycling, climate change, lake sediment, palsa mire, peat, permafrost decay, precipitation, soil moisture},\n\tpages = {1652--1663},\n}\n\n\n\n\n\n Recent accelerated decay of discontinuous permafrost at the Stordalen Mire in northern Sweden has been attributed to increased temperature and snow depth, and has caused expansion of wet minerotrophic areas leading to significant changes in carbon cycling in the mire. In order to track these changes through time and evaluate potential forcing mechanisms, this paper analyses a peat succession and a lake sediment sequence from within the mire, providing a record for the last 100 years, and compares these with monitored climate and active layer thickness data. The peat core was analysed for testate amoebae to reconstruct changes in peatland surface moisture conditions and water table fluctuations. The lake sediment core was analysed by near infrared spectroscopy to infer changes in the total organic carbon (TOC) concentration of the lake-water, and changes in δ13C and C, N and δ15N to track changes in the dissolved inorganic carbon (DIC) pool and the influence of diagenetic effects on sediment organic matter, respectively. Results showed that major shifts towards increased peat surface moisture and TOC concentration of the lake-water occurred around 1980, one to two decades earlier than a temperature driven increase in active layer thickness. Comparison with monitored temperature and precipitation from a nearby climate station indicates that this change in peat surface moisture is related to June–September (JJAS) precipitation and that the increase in lake-water TOC concentration reflects an increase in total annual precipitation. A significant depletion in 13C of sediment organic matter in the early 1980s probably reflects the effect of a single or a few consecutive years with anomalously high summer precipitation, resulting in elevated DIC content of the lake water, predominantly originating from increased export and subsequent respiration of organic carbon from the mire. Based on these results, it was not possible to link proxy data obtained on peat and lake-sediment records directly to permafrost decay. Instead our data indicate that increased precipitation and anomalously high rainfall during summers had a significant impact on the mire and the adjacent lake ecosystem. We therefore propose that effects of increased precipitation should be considered when evaluating potential forcing mechanisms of recent changes in carbon cycling in the subarctic.\n
\n\n\n\n \n\n \n \n \n \n \n Nonlinear response of dissolved organic carbon concentrations in boreal lakes to increasing temperatures.\n \n \n \n\n\n \n Weyhenmeyer, G. A.; and Karlsson, J.\n\n\n \n\n\n\n Limnology and Oceanography, 54(6): 2513–2519. November 2009.\n 00085\n\n\n\n
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\n\n\n@article{weyhenmeyer_nonlinear_2009,\n\ttitle = {Nonlinear response of dissolved organic carbon concentrations in boreal lakes to increasing temperatures},\n\tvolume = {54},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2009.54.6_part_2.2513},\n\tabstract = {Recent increases in concentrations of dissolved organic carbon (DOC) in lakes and rivers over large regions have been related to both changes in the climate and in atmospheric deposition chemistry. Using a data set of 1041 boreal lakes along a 13 degrees latitudinal gradient, sampled in 1995, 2000, and 2005, and an additional data set of 90 lakes along a 1000-m altitudinal gradient at 68 degrees N, we show that DOC concentrations increase in a nonlinear way along a latitudinal and altitudinal temperature gradient. The nonlinear relation of DOC to increasing temperatures was consistent over space and time. Out of 14 meteorological, catchment, morphometric, and atmospheric deposition variables tested, the variable best explaining this kind of nonlinear pattern was the number of days when air temperatures exceeded 0 degrees C, i.e., the duration of the main growing and runoff season (D-T{\\textgreater}0). Using D-T{\\textgreater}0 as an input variable, we were able to predict the nonlinear temperature response of DOC concentrations, both spatially (R-2 = 0.90, p {\\textless} 0.0001) and temporally (R-2 = 0.90, p {\\textless} 0.0001). D-T{\\textgreater}0 has an advantage over other variables because it includes the time factor, which is decisive for the duration that biogeochemical processes can take place. We suggest that DOC concentrations in lakes are influenced by climate change and that present temperature increases over Sweden result in an accelerated DOC increase toward warmer geographical regions.},\n\tlanguage = {English},\n\tnumber = {6},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Weyhenmeyer, Gesa A. and Karlsson, Jan},\n\tmonth = nov,\n\tyear = {2009},\n\tnote = {00085},\n\tkeywords = {\\#nosource, air-temperature, atmospheric deposition, climate, export, matter, precipitation, respiration, terrestrial carbon, trends, water},\n\tpages = {2513--2519},\n}\n\n\n\n\n\n Recent increases in concentrations of dissolved organic carbon (DOC) in lakes and rivers over large regions have been related to both changes in the climate and in atmospheric deposition chemistry. Using a data set of 1041 boreal lakes along a 13 degrees latitudinal gradient, sampled in 1995, 2000, and 2005, and an additional data set of 90 lakes along a 1000-m altitudinal gradient at 68 degrees N, we show that DOC concentrations increase in a nonlinear way along a latitudinal and altitudinal temperature gradient. The nonlinear relation of DOC to increasing temperatures was consistent over space and time. Out of 14 meteorological, catchment, morphometric, and atmospheric deposition variables tested, the variable best explaining this kind of nonlinear pattern was the number of days when air temperatures exceeded 0 degrees C, i.e., the duration of the main growing and runoff season (D-T\\textgreater0). Using D-T\\textgreater0 as an input variable, we were able to predict the nonlinear temperature response of DOC concentrations, both spatially (R-2 = 0.90, p \\textless 0.0001) and temporally (R-2 = 0.90, p \\textless 0.0001). D-T\\textgreater0 has an advantage over other variables because it includes the time factor, which is decisive for the duration that biogeochemical processes can take place. We suggest that DOC concentrations in lakes are influenced by climate change and that present temperature increases over Sweden result in an accelerated DOC increase toward warmer geographical regions.\n
\n\n\n\n \n\n \n \n \n \n \n High Ratio of Bacteriochlorophyll Biosynthesis Genes to Chlorophyll Biosynthesis Genes in Bacteria of Humic Lakes.\n \n \n \n\n\n \n Eiler, A.; Beier, S.; Sawstrom, C.; Karlsson, J.; and Bertilsson, S.\n\n\n \n\n\n\n Applied and Environmental Microbiology, 75(22): 7221–7228. November 2009.\n \n\n\n\n
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\n\n\n@article{eiler_high_2009,\n\ttitle = {High {Ratio} of {Bacteriochlorophyll} {Biosynthesis} {Genes} to {Chlorophyll} {Biosynthesis} {Genes} in {Bacteria} of {Humic} {Lakes}},\n\tvolume = {75},\n\tissn = {0099-2240},\n\tdoi = {10.1128/AEM.00960-09},\n\tabstract = {Recent studies highlight the diversity and significance of marine phototrophic microorganisms such as picocyanobacteria, phototrophic picoeukaryotes, and bacteriochlorophyll-and rhodopsin-holding phototrophic bacteria. To assess if freshwater ecosystems also harbor similar phototroph diversity, genes involved in the biosynthesis of bacteriochlorophyll and chlorophyll were targeted to explore oxygenic and aerobic anoxygenic phototroph composition in a wide range of lakes. Partial dark-operative protochlorophyllide oxidoreductase (DPOR) and chlorophyllide oxidoreductase (COR) genes in bacteria of seven lakes with contrasting trophic statuses were PCR amplified, cloned, and sequenced. Out of 61 sequences encoding the L subunit of DPOR (L-DPOR), 22 clustered with aerobic anoxygenic photosynthetic bacteria, whereas 39 L-DPOR sequences related to oxygenic phototrophs, like cyanobacteria, were observed. Phylogenetic analysis revealed clear separation of these freshwater L-DPOR genes as well as 11 COR gene sequences from their marine counterparts. Terminal restriction fragment length analysis of L-DPOR genes was used to characterize oxygenic aerobic and anoxygenic photosynthesizing populations in 20 lakes differing in physical and chemical characteristics. Significant differences in L-DPOR community composition were observed between dystrophic lakes and all other systems, where a higher proportion of genes affiliated with aerobic anoxygenic photosynthetic bacteria was observed than in other systems. Our results reveal a significant diversity of phototrophic microorganisms in lakes and suggest niche partitioning of oxygenic and aerobic anoxygenic phototrophs in these systems in response to trophic status and coupled differences in light regime.},\n\tlanguage = {English},\n\tnumber = {22},\n\tjournal = {Applied and Environmental Microbiology},\n\tauthor = {Eiler, Alexander and Beier, Sara and Sawstrom, Christin and Karlsson, Jan and Bertilsson, Stefan},\n\tmonth = nov,\n\tyear = {2009},\n\tkeywords = {\\#nosource, anoxygenic phototrophic bacteria, carbon, community structure, cyanobacterium plectonema-boryanum, diversity, ocean sampling expedition, photosynthesis, sea, sequence alignment, surface waters},\n\tpages = {7221--7228},\n}\n\n\n\n\n\n Recent studies highlight the diversity and significance of marine phototrophic microorganisms such as picocyanobacteria, phototrophic picoeukaryotes, and bacteriochlorophyll-and rhodopsin-holding phototrophic bacteria. To assess if freshwater ecosystems also harbor similar phototroph diversity, genes involved in the biosynthesis of bacteriochlorophyll and chlorophyll were targeted to explore oxygenic and aerobic anoxygenic phototroph composition in a wide range of lakes. Partial dark-operative protochlorophyllide oxidoreductase (DPOR) and chlorophyllide oxidoreductase (COR) genes in bacteria of seven lakes with contrasting trophic statuses were PCR amplified, cloned, and sequenced. Out of 61 sequences encoding the L subunit of DPOR (L-DPOR), 22 clustered with aerobic anoxygenic photosynthetic bacteria, whereas 39 L-DPOR sequences related to oxygenic phototrophs, like cyanobacteria, were observed. Phylogenetic analysis revealed clear separation of these freshwater L-DPOR genes as well as 11 COR gene sequences from their marine counterparts. Terminal restriction fragment length analysis of L-DPOR genes was used to characterize oxygenic aerobic and anoxygenic photosynthesizing populations in 20 lakes differing in physical and chemical characteristics. Significant differences in L-DPOR community composition were observed between dystrophic lakes and all other systems, where a higher proportion of genes affiliated with aerobic anoxygenic photosynthetic bacteria was observed than in other systems. Our results reveal a significant diversity of phototrophic microorganisms in lakes and suggest niche partitioning of oxygenic and aerobic anoxygenic phototrophs in these systems in response to trophic status and coupled differences in light regime.\n
\n\n\n\n \n\n \n \n \n \n \n \n Bioavailability of terrestrial organic carbon to lake bacteria: The case of a degrading subarctic permafrost mire complex.\n \n \n \n \n\n\n \n Roehm, C. L.; Giesler, R.; and Karlsson, J.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 114(G3): G03006. September 2009.\n \n\n\n\n
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\n\n\n@article{roehm_bioavailability_2009,\n\ttitle = {Bioavailability of terrestrial organic carbon to lake bacteria: {The} case of a degrading subarctic permafrost mire complex},\n\tvolume = {114},\n\tissn = {2156-2202},\n\tshorttitle = {Bioavailability of terrestrial organic carbon to lake bacteria},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2008JG000863/abstract},\n\tdoi = {10.1029/2008JG000863},\n\tabstract = {Permafrost degradation can result in the loss of significant amounts of carbon, through release to the atmosphere in the form of carbon dioxide and/or methane and through export downstream to lakes and rivers. The fate of this carbon in lake ecosystems is poorly understood. We investigated the capacity of lake bacteria to utilize carbon from different soils from an adjacent mire. Dark bioassays were undertaken to measure the dynamics of the bioavailability and chemical character of dissolved organic carbon (DOC). The soils ranged from already degraded minerotrophic fens to ombrotrophic active layer and soils from the permafrost layer. Our study shows that soil DOC was rapidly consumed by bacteria collected from lake water, particularly within the first 48 h (about 85\\% of the total consumed DOC). The mean DOC consumption by lake bacteria was 0.087 mg L−1 d−1 when supplied with lake water DOC and varied between 0.382 mg L−1 d−1 (permafrost soil) and 0.491 mg L−1 d−1 (degraded fen soil) when supplied with terrestrial DOC. Thus, the data suggest that export of DOC from degrading permafrost mires at any stage of degradation can potentially increase rates of respiration by fourfold to sevenfold and can have pronounced effects both on receiving lake ecosystems and on the land-atmosphere carbon balance. In this study we also propose simple predictive models, incorporating weight-averaged molecular weight and specific UV absorption in combination with other simple qualitative parameters for the estimation of potential bioavailability of soil DOC in aquatic ecosystems.},\n\tlanguage = {en},\n\tnumber = {G3},\n\turldate = {2017-02-06},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Roehm, Charlotte L. and Giesler, Reiner and Karlsson, Jan},\n\tmonth = sep,\n\tyear = {2009},\n\tkeywords = {\\#nosource, 0400 Biogeosciences, 0458 Limnology, 0475 Permafrost, cryosphere, and high-latitude processes, 0486 Soils/pedology, Biogeosciences, Limnology, Permafrost, cryosphere, and high-latitude processes, Soils/pedology, allochthonous, aquatic metabolism, dissolved organic carbon, lability, permafrost},\n\tpages = {G03006},\n}\n\n\n\n\n\n Permafrost degradation can result in the loss of significant amounts of carbon, through release to the atmosphere in the form of carbon dioxide and/or methane and through export downstream to lakes and rivers. The fate of this carbon in lake ecosystems is poorly understood. We investigated the capacity of lake bacteria to utilize carbon from different soils from an adjacent mire. Dark bioassays were undertaken to measure the dynamics of the bioavailability and chemical character of dissolved organic carbon (DOC). The soils ranged from already degraded minerotrophic fens to ombrotrophic active layer and soils from the permafrost layer. Our study shows that soil DOC was rapidly consumed by bacteria collected from lake water, particularly within the first 48 h (about 85% of the total consumed DOC). The mean DOC consumption by lake bacteria was 0.087 mg L−1 d−1 when supplied with lake water DOC and varied between 0.382 mg L−1 d−1 (permafrost soil) and 0.491 mg L−1 d−1 (degraded fen soil) when supplied with terrestrial DOC. Thus, the data suggest that export of DOC from degrading permafrost mires at any stage of degradation can potentially increase rates of respiration by fourfold to sevenfold and can have pronounced effects both on receiving lake ecosystems and on the land-atmosphere carbon balance. In this study we also propose simple predictive models, incorporating weight-averaged molecular weight and specific UV absorption in combination with other simple qualitative parameters for the estimation of potential bioavailability of soil DOC in aquatic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Benthic algae support zooplankton growth during winter in a clear-water lake.\n \n \n \n \n\n\n \n Karlsson, J.; and Säwström, C.\n\n\n \n\n\n\n Oikos, 118(4): 539–544. April 2009.\n 00031\n\n\n\n
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\n\n\n@article{karlsson_benthic_2009,\n\ttitle = {Benthic algae support zooplankton growth during winter in a clear-water lake},\n\tvolume = {118},\n\tissn = {1600-0706},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0706.2008.17239.x/abstract},\n\tdoi = {10.1111/j.1600-0706.2008.17239.x},\n\tabstract = {We used stable carbon (δ13C) and nitrogen (δ15N) isotopes to assess the importance of benthic algae for the zooplankton individual growth in winter in a shallow, clear subarctic lake. The δ13C values of calanoid (Eudiaptomus graciloides) and cyclopoid (Cyclops scutifer) zooplankton in autumn suggest a food resource of pelagic origin during the ice-free period. The zooplankton δ13C values were high in spring compared to autumn. E. graciloides did not grow over winter and the change in δ13C was attributed to a decrease in lipid content during the winter. In contrast, the increase in δ13C values of C. scutifer over the winter was explained by their growth on organic carbon generated by benthic algae. The δ15N of the C. scutifer food resource during winter was low compared to δ15N of the benthic community, suggesting that organic matter generated by benthic algae was mainly channelled to zooplankton via 15N-depleted heterotrophic bacteria. The results demonstrate that benthic algae can sustain zooplankton metabolic demands and growth during long winters, which, in turn, may promote zooplankton growth on pelagic resources during the summer. Such multi-chain omnivory challenges the view of zooplankton as mainly dependent on internal primary production and stresses the importance of benthic resources for the productivity of plankton food webs in shallow lakes.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-06},\n\tjournal = {Oikos},\n\tauthor = {Karlsson, Jan and Säwström, Christin},\n\tmonth = apr,\n\tyear = {2009},\n\tnote = {00031},\n\tkeywords = {\\#nosource},\n\tpages = {539--544},\n}\n\n\n\n\n\n We used stable carbon (δ13C) and nitrogen (δ15N) isotopes to assess the importance of benthic algae for the zooplankton individual growth in winter in a shallow, clear subarctic lake. The δ13C values of calanoid (Eudiaptomus graciloides) and cyclopoid (Cyclops scutifer) zooplankton in autumn suggest a food resource of pelagic origin during the ice-free period. The zooplankton δ13C values were high in spring compared to autumn. E. graciloides did not grow over winter and the change in δ13C was attributed to a decrease in lipid content during the winter. In contrast, the increase in δ13C values of C. scutifer over the winter was explained by their growth on organic carbon generated by benthic algae. The δ15N of the C. scutifer food resource during winter was low compared to δ15N of the benthic community, suggesting that organic matter generated by benthic algae was mainly channelled to zooplankton via 15N-depleted heterotrophic bacteria. The results demonstrate that benthic algae can sustain zooplankton metabolic demands and growth during long winters, which, in turn, may promote zooplankton growth on pelagic resources during the summer. Such multi-chain omnivory challenges the view of zooplankton as mainly dependent on internal primary production and stresses the importance of benthic resources for the productivity of plankton food webs in shallow lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal climate manipulations result in species-specific changes in leaf nutrient levels and isotopic composition in a sub-arctic bog.\n \n \n \n \n\n\n \n Aerts, R.; Callaghan, T. V.; Dorrepaal, E.; Van Logtestijn, R. S. P.; and Cornelissen, J. H. C.\n\n\n \n\n\n\n Functional Ecology, 23(4): 680–688. August 2009.\n \n\n\n\n
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\n\n\n@article{aerts_seasonal_2009,\n\ttitle = {Seasonal climate manipulations result in species-specific changes in leaf nutrient levels and isotopic composition in a sub-arctic bog},\n\tvolume = {23},\n\tissn = {1365-2435},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2009.01566.x/abstract},\n\tdoi = {10.1111/j.1365-2435.2009.01566.x},\n\tabstract = {* 1Climate change in cold biomes not only involves higher summer temperatures, but also warmer springs and more winter precipitation. So far, little is known about species responses to these seasonal components of climate change.\n* 2We experimentally manipulated spring and summer temperatures and winter snow accumulation and temperatures independently in a peatland in sub-arctic Sweden. This yielded six climate scenarios and we studied the responses of the peat moss Sphagnum fuscum, the evergreen dwarf shrubs Empetrum hermaphroditum and Andromeda polifolia, the deciduous dwarf shrubs Betula nana and Vaccinium uliginosum, the grass Calamagrostis lapponica and the forb Rubus chamaemorus.\n* 3We found substantial interspecific differences in leaf nutrient and carbon exchange variables that reflect the response of tundra plants to climate change. S. fuscum had the lowest N and P concentrations, with increasing N and P concentrations (and decreasing C/N and C/P ratios) going from evergreen dwarf shrubs, to the grass, deciduous dwarf shrubs and the forb. Leaf N/P ratios varied between 10 and 14 which points to N-limited plant growth.\n* 4The natural abundance of 15N varied very strongly among species and growth forms. These differences corresponded with the presence and type of mycorrhizal association in the plant roots. Leaf carbon isotope discrimination also differed strongly among species and growth forms, but the absolute differences were relatively small ({\\textless} 5‰). The rank order was: forb and graminoid {\\textless} moss and evergreen shrubs {\\textless} deciduous shrubs.\n* 5After 4 years, the effects of realistic climate change manipulations on leaf nutrient and carbon exchange variables were idiosyncratic with respect to species and generally small compared to the differences among species and growth forms. At the phenotypic level, spring warming or winter snow addition effects occurred as frequently as summer warming effects.\n* 6This implies that the changes in the species composition and structure of plant communities that have been observed in medium-term warming studies in cold biomes will have much more impact on plant-mediated nutrient and carbon cycling pathways and rates than climate-change induced phenotypic responses, irrespective of the seasonal timing of these climate changes.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-08},\n\tjournal = {Functional Ecology},\n\tauthor = {Aerts, Rien and Callaghan, Terry V. and Dorrepaal, Ellen and Van Logtestijn, Richard S. P. and Cornelissen, Johannes H. C.},\n\tmonth = aug,\n\tyear = {2009},\n\tkeywords = {\\#nosource, growth forms, isotopic composition, plant-soil feedbacks, soil nutrient mineralization, tundra},\n\tpages = {680--688},\n}\n\n\n\n\n\n * 1Climate change in cold biomes not only involves higher summer temperatures, but also warmer springs and more winter precipitation. So far, little is known about species responses to these seasonal components of climate change. * 2We experimentally manipulated spring and summer temperatures and winter snow accumulation and temperatures independently in a peatland in sub-arctic Sweden. This yielded six climate scenarios and we studied the responses of the peat moss Sphagnum fuscum, the evergreen dwarf shrubs Empetrum hermaphroditum and Andromeda polifolia, the deciduous dwarf shrubs Betula nana and Vaccinium uliginosum, the grass Calamagrostis lapponica and the forb Rubus chamaemorus. * 3We found substantial interspecific differences in leaf nutrient and carbon exchange variables that reflect the response of tundra plants to climate change. S. fuscum had the lowest N and P concentrations, with increasing N and P concentrations (and decreasing C/N and C/P ratios) going from evergreen dwarf shrubs, to the grass, deciduous dwarf shrubs and the forb. Leaf N/P ratios varied between 10 and 14 which points to N-limited plant growth. * 4The natural abundance of 15N varied very strongly among species and growth forms. These differences corresponded with the presence and type of mycorrhizal association in the plant roots. Leaf carbon isotope discrimination also differed strongly among species and growth forms, but the absolute differences were relatively small (\\textless 5‰). The rank order was: forb and graminoid \\textless moss and evergreen shrubs \\textless deciduous shrubs. * 5After 4 years, the effects of realistic climate change manipulations on leaf nutrient and carbon exchange variables were idiosyncratic with respect to species and generally small compared to the differences among species and growth forms. At the phenotypic level, spring warming or winter snow addition effects occurred as frequently as summer warming effects. * 6This implies that the changes in the species composition and structure of plant communities that have been observed in medium-term warming studies in cold biomes will have much more impact on plant-mediated nutrient and carbon cycling pathways and rates than climate-change induced phenotypic responses, irrespective of the seasonal timing of these climate changes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Whole-lake estimates of carbon flux through algae and bacteria in benthic and pelagic habitats of clear-water lakes.\n \n \n \n \n\n\n \n Ask, J.; Karlsson, J.; Persson, L.; Ask, P.; Byström, P.; and Jansson, M.\n\n\n \n\n\n\n Ecology, 90(7): 1923–1932. July 2009.\n 00082\n\n\n\n
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\n\n\n@article{ask_whole-lake_2009,\n\ttitle = {Whole-lake estimates of carbon flux through algae and bacteria in benthic and pelagic habitats of clear-water lakes},\n\tvolume = {90},\n\tissn = {1939-9170},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/07-1855.1/abstract},\n\tdoi = {10.1890/07-1855.1},\n\tabstract = {This study quantified new biomass production of algae and bacteria in both benthic and pelagic habitats of clear-water lakes to contrast how carbon from the atmosphere and terrestrial sources regulates whole-lake metabolism. We studied four small unproductive lakes in subarctic northern Sweden during one summer season. The production of new biomass in both benthic and pelagic habitats was calculated as the sum of autotrophic production by algae and heterotrophic production by bacteria using allochthonous organic carbon (OC). Whole-lake production of new biomass was dominated by the benthic habitat (86\\% ± 4\\% [mean ± SD]) and by primary production (77\\% ± 9\\%). Still, heterotrophic bacteria fueled by allochthonous OC constituted a significant portion of the new biomass production in both benthic (19\\% ± 11\\%) and pelagic habitats (51\\% ± 24\\%). In addition, overall net production (primary production minus respiration) was close to zero in the benthic habitats but highly negative (−163 ± 81 mg C·m−2·d−1) in pelagic regions of all lakes. We conclude (1) that allochthonous OC supported a significant part of total production of new biomass in both pelagic and benthic habitats, (2) that benthic habitats dominated the whole-lake production of new biomass, and (3) that respiration and net CO2 production dominated the carbon flux of the pelagic habitats and biomass production dominated the benthic carbon flux. Taken together, these findings suggest that previous investigations have greatly underestimated the productivity of clear-water lakes when benthic autotrophic production and metabolism of allochthonous OC have not been measured.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-06},\n\tjournal = {Ecology},\n\tauthor = {Ask, Jenny and Karlsson, Jan and Persson, Lennart and Ask, Per and Byström, Pär and Jansson, Mats},\n\tmonth = jul,\n\tyear = {2009},\n\tnote = {00082},\n\tkeywords = {\\#nosource, allochthonous organic carbon, autotrophy, bacterial production, benthic, clear-water lakes, heterotrophy, metabolism, net ecosystem production, pelagic, primary production, respiration},\n\tpages = {1923--1932},\n}\n\n\n\n\n\n This study quantified new biomass production of algae and bacteria in both benthic and pelagic habitats of clear-water lakes to contrast how carbon from the atmosphere and terrestrial sources regulates whole-lake metabolism. We studied four small unproductive lakes in subarctic northern Sweden during one summer season. The production of new biomass in both benthic and pelagic habitats was calculated as the sum of autotrophic production by algae and heterotrophic production by bacteria using allochthonous organic carbon (OC). Whole-lake production of new biomass was dominated by the benthic habitat (86% ± 4% [mean ± SD]) and by primary production (77% ± 9%). Still, heterotrophic bacteria fueled by allochthonous OC constituted a significant portion of the new biomass production in both benthic (19% ± 11%) and pelagic habitats (51% ± 24%). In addition, overall net production (primary production minus respiration) was close to zero in the benthic habitats but highly negative (−163 ± 81 mg C·m−2·d−1) in pelagic regions of all lakes. We conclude (1) that allochthonous OC supported a significant part of total production of new biomass in both pelagic and benthic habitats, (2) that benthic habitats dominated the whole-lake production of new biomass, and (3) that respiration and net CO2 production dominated the carbon flux of the pelagic habitats and biomass production dominated the benthic carbon flux. Taken together, these findings suggest that previous investigations have greatly underestimated the productivity of clear-water lakes when benthic autotrophic production and metabolism of allochthonous OC have not been measured.\n
\n\n\n\n \n\n \n \n \n \n \n Carbon respiration from subsurface peat accelerated by climate warming in the subarctic.\n \n \n \n\n\n \n Dorrepaal, E.; Toet, S.; van Logtestijn, R. S. P.; Swart, E.; van de Weg, M. J.; Callaghan, T. V.; and Aerts, R.\n\n\n \n\n\n\n Nature, 460(7255): 616–U79. July 2009.\n \n\n\n\n
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\n\n\n@article{dorrepaal_carbon_2009,\n\ttitle = {Carbon respiration from subsurface peat accelerated by climate warming in the subarctic},\n\tvolume = {460},\n\tissn = {0028-0836},\n\tdoi = {10.1038/nature08216},\n\tabstract = {Among the largest uncertainties in current projections of future climate is the feedback between the terrestrial carbon cycle and climate(1). Northern peatlands contain one-third of the world's soil organic carbon, equivalent to more than half the amount of carbon in the atmosphere(2). Climate-warming-induced acceleration of carbon dioxide (CO(2)) emissions through enhanced respiration of thick peat deposits, centuries to millennia old, may form a strong positive carbon cycle-climate feedback. The long-term temperature sensitivity of carbon in peatlands, especially at depth, remains uncertain, however, because of the short duration or correlative nature of field studies(3-5) and the disturbance associated with respiration measurements below the surface in situ or during laboratory incubations(6,7). Here we combine non-disturbing in situ measurements of CO(2) respiration rates and isotopic ((13)C) composition of respired CO(2) in two whole-ecosystem climate-manipulation experiments in a subarctic peatland. We show that approximately 1 degrees C warming accelerated total ecosystem respiration rates on average by 60\\% in spring and by 52\\% in summer and that this effect was sustained for at least eight years. While warming stimulated both short-term (plant-related) and longer-term (peat soil-related) carbon respiration processes, we find that at least 69\\% of the increase in respiration rate originated from carbon in peat towards the bottom (25-50 cm) of the active layer above the permafrost. Climate warming therefore accelerates respiration of the extensive, subsurface carbon reservoirs in peatlands to a much larger extent than was previously thought(6,7). Assuming that our data from a single site are indicative of the direct response to warming of northern peatland soils on a global scale, we estimate that climate warming of about 1 degrees C over the next few decades could induce a global increase in heterotrophic respiration of 38-100 megatonnes of C per year. Our findings suggest a large, long-lasting, positive feedback of carbon stored in northern peatlands to the global climate system.},\n\tlanguage = {English},\n\tnumber = {7255},\n\tjournal = {Nature},\n\tauthor = {Dorrepaal, Ellen and Toet, Sylvia and van Logtestijn, Richard S. P. and Swart, Elferra and van de Weg, Martine J. and Callaghan, Terry V. and Aerts, Rien},\n\tmonth = jul,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Decomposition, Mineralization, Temperature sensitivity, bog, cycle, ecosystem, growth, natural-abundance, soil co2 efflux, water-table},\n\tpages = {616--U79},\n}\n\n\n\n\n\n Among the largest uncertainties in current projections of future climate is the feedback between the terrestrial carbon cycle and climate(1). Northern peatlands contain one-third of the world's soil organic carbon, equivalent to more than half the amount of carbon in the atmosphere(2). Climate-warming-induced acceleration of carbon dioxide (CO(2)) emissions through enhanced respiration of thick peat deposits, centuries to millennia old, may form a strong positive carbon cycle-climate feedback. The long-term temperature sensitivity of carbon in peatlands, especially at depth, remains uncertain, however, because of the short duration or correlative nature of field studies(3-5) and the disturbance associated with respiration measurements below the surface in situ or during laboratory incubations(6,7). Here we combine non-disturbing in situ measurements of CO(2) respiration rates and isotopic ((13)C) composition of respired CO(2) in two whole-ecosystem climate-manipulation experiments in a subarctic peatland. We show that approximately 1 degrees C warming accelerated total ecosystem respiration rates on average by 60% in spring and by 52% in summer and that this effect was sustained for at least eight years. While warming stimulated both short-term (plant-related) and longer-term (peat soil-related) carbon respiration processes, we find that at least 69% of the increase in respiration rate originated from carbon in peat towards the bottom (25-50 cm) of the active layer above the permafrost. Climate warming therefore accelerates respiration of the extensive, subsurface carbon reservoirs in peatlands to a much larger extent than was previously thought(6,7). Assuming that our data from a single site are indicative of the direct response to warming of northern peatland soils on a global scale, we estimate that climate warming of about 1 degrees C over the next few decades could induce a global increase in heterotrophic respiration of 38-100 megatonnes of C per year. Our findings suggest a large, long-lasting, positive feedback of carbon stored in northern peatlands to the global climate system.\n
\n\n\n\n \n\n \n \n \n \n \n \n What does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams? A synthetic study from Hong Kong.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n Freshwater Biology, 54(1): 127–141. January 2009.\n \n\n\n\n
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\n\n\n@article{lau_what_2009,\n\ttitle = {What does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams? {A} synthetic study from {Hong} {Kong}},\n\tvolume = {54},\n\tissn = {1365-2427},\n\tshorttitle = {What does stable isotope analysis reveal about trophic relationships and the relative importance of allochthonous and autochthonous resources in tropical streams?},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1365-2427.2008.02099.x/abstract},\n\tdoi = {10.1111/j.1365-2427.2008.02099.x},\n\tabstract = {1. Analysis of the stable isotope signatures of carbon (C) and nitrogen (N) of foods and consumers has led to some preliminary understanding of the relative importance of autochthonous and allochthonous resources in tropical streams. However, robust generalizations about the dynamics of food webs in these habitats, and their response to shading gradients or season, are still lacking. In addition, the feasibility of employing a baseline δ15N value for estimating trophic positions (TPs) of consumers in small tropical streams has yet to be explored. 2. We analysed data on stable isotope signatures of food sources and aquatic consumers obtained from 14 studies carried out in small streams in monsoonal Hong Kong (22°30′N, 114°10′E) between 1996 and 2006. Emphasis was placed on determining the relative importance of leaf litter and autochthonous foods in supporting consumer biomass, and the extent to which trophic base and TP vary among streams and seasons. 3. Although allochthonous leaf litter was generally 13C- and 15N-depleted relative to autochthonous foods, there were marked isotopic shifts of food sources and consumers in response to season (dry versus wet) and stream shading. Consumer taxa were generally more 13C- and 15N-enriched in the unshaded streams, but seasonal effects were more variable. Despite these changes, there was consistent evidence that stream food webs were based on periphytic algae and/or cyanobacteria with leaf litter serving as a minor food. 4. Heptageniidae (Ephemeroptera), Tipulidae (Diptera), Elmidae (Coleoptera) and shrimps (Atyidae) were used as a baseline for calculating the TPs of other consumer taxa. The maximum TPs in shaded streams remained fairly constant between seasons (dry = 3.93; wet = 3.97), while those in unshaded streams were higher and showed seasonal fluctuations (dry = 5.13; wet = 4.39). 5. Although variations in consumer isotope signatures in response to season and shading gradients did not confound our interpretation of the stream food base, changes in consumer δ15N did affect the calculation of consumer TPs. Misleading estimates of consumer TPs are likely if samples are collected from a narrow range of streams and/or during one season. Overestimation of the TPs of specialist herbivores (e.g. fish grazers) is also possible when autochthonous resources are substantially more 15N-enriched than allochthonous foods.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-05-27},\n\tjournal = {Freshwater Biology},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y. and Dudgeon, David},\n\tmonth = jan,\n\tyear = {2009},\n\tkeywords = {\\#nosource, energy flow, food web, riparian shading, seasonal effect, trophic position},\n\tpages = {127--141},\n}\n\n\n\n\n\n 1. Analysis of the stable isotope signatures of carbon (C) and nitrogen (N) of foods and consumers has led to some preliminary understanding of the relative importance of autochthonous and allochthonous resources in tropical streams. However, robust generalizations about the dynamics of food webs in these habitats, and their response to shading gradients or season, are still lacking. In addition, the feasibility of employing a baseline δ15N value for estimating trophic positions (TPs) of consumers in small tropical streams has yet to be explored. 2. We analysed data on stable isotope signatures of food sources and aquatic consumers obtained from 14 studies carried out in small streams in monsoonal Hong Kong (22°30′N, 114°10′E) between 1996 and 2006. Emphasis was placed on determining the relative importance of leaf litter and autochthonous foods in supporting consumer biomass, and the extent to which trophic base and TP vary among streams and seasons. 3. Although allochthonous leaf litter was generally 13C- and 15N-depleted relative to autochthonous foods, there were marked isotopic shifts of food sources and consumers in response to season (dry versus wet) and stream shading. Consumer taxa were generally more 13C- and 15N-enriched in the unshaded streams, but seasonal effects were more variable. Despite these changes, there was consistent evidence that stream food webs were based on periphytic algae and/or cyanobacteria with leaf litter serving as a minor food. 4. Heptageniidae (Ephemeroptera), Tipulidae (Diptera), Elmidae (Coleoptera) and shrimps (Atyidae) were used as a baseline for calculating the TPs of other consumer taxa. The maximum TPs in shaded streams remained fairly constant between seasons (dry = 3.93; wet = 3.97), while those in unshaded streams were higher and showed seasonal fluctuations (dry = 5.13; wet = 4.39). 5. Although variations in consumer isotope signatures in response to season and shading gradients did not confound our interpretation of the stream food base, changes in consumer δ15N did affect the calculation of consumer TPs. Misleading estimates of consumer TPs are likely if samples are collected from a narrow range of streams and/or during one season. Overestimation of the TPs of specialist herbivores (e.g. fish grazers) is also possible when autochthonous resources are substantially more 15N-enriched than allochthonous foods.\n
\n\n\n\n \n\n \n \n \n \n \n Light limitation of nutrient-poor lake ecosystems.\n \n \n \n\n\n \n Karlsson, J.; Byström, P.; Ask, J.; Ask, P.; Persson, L.; and Jansson, M.\n\n\n \n\n\n\n Nature, 460(7254): 506–U80. July 2009.\n \n\n\n\n
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\n\n\n@article{karlsson_light_2009,\n\ttitle = {Light limitation of nutrient-poor lake ecosystems},\n\tvolume = {460},\n\tissn = {0028-0836},\n\tdoi = {10.1038/nature08179},\n\tabstract = {Productivity denotes the rate of biomass synthesis in ecosystems and is a fundamental characteristic that frames ecosystem function and management. Limitation of productivity by nutrient availability is an established paradigm for lake ecosystems(1-3). Here, we assess the relevance of this paradigm for a majority of the world's small, nutrient-poor lakes, with different concentrations of coloured organic matter(4,5). By comparing small unproductive lakes along a water colour gradient, we show that coloured terrestrial organic matter controls the key process for new biomass synthesis (the benthic primary production) through its effects on light attenuation. We also show that this translates into effects on production and biomass of higher trophic levels (benthic invertebrates and fish). These results are inconsistent with the idea that nutrient supply primarily controls lake productivity, and we propose that a large share of the world's unproductive lakes, within natural variations of organic carbon and nutrient input, are limited by light and not by nutrients. We anticipate that our result will have implications for understanding lake ecosystem function and responses to environmental change. Catchment export of coloured organic matter is sensitive to short-term natural variability and long-term, large-scale changes, driven by climate and different anthropogenic influences(6,7). Consequently, changes in terrestrial carbon cycling will have pronounced effects on most lake ecosystems by mediating changes in light climate and productivity of lakes.},\n\tlanguage = {English},\n\tnumber = {7254},\n\tjournal = {Nature},\n\tauthor = {Karlsson, Jan and Byström, Pär and Ask, Jenny and Ask, Per and Persson, Lennart and Jansson, Mats},\n\tmonth = jul,\n\tyear = {2009},\n\tkeywords = {\\#nosource, biomass, clear-water lakes, dissolved organic-carbon, eutrophication, export, food webs, impact, phosphorus limitation},\n\tpages = {506--U80},\n}\n\n\n\n\n\n Productivity denotes the rate of biomass synthesis in ecosystems and is a fundamental characteristic that frames ecosystem function and management. Limitation of productivity by nutrient availability is an established paradigm for lake ecosystems(1-3). Here, we assess the relevance of this paradigm for a majority of the world's small, nutrient-poor lakes, with different concentrations of coloured organic matter(4,5). By comparing small unproductive lakes along a water colour gradient, we show that coloured terrestrial organic matter controls the key process for new biomass synthesis (the benthic primary production) through its effects on light attenuation. We also show that this translates into effects on production and biomass of higher trophic levels (benthic invertebrates and fish). These results are inconsistent with the idea that nutrient supply primarily controls lake productivity, and we propose that a large share of the world's unproductive lakes, within natural variations of organic carbon and nutrient input, are limited by light and not by nutrients. We anticipate that our result will have implications for understanding lake ecosystem function and responses to environmental change. Catchment export of coloured organic matter is sensitive to short-term natural variability and long-term, large-scale changes, driven by climate and different anthropogenic influences(6,7). Consequently, changes in terrestrial carbon cycling will have pronounced effects on most lake ecosystems by mediating changes in light climate and productivity of lakes.\n
\n\n\n\n \n\n \n \n \n \n \n Terrestrial organic matter and light penetration: Effects on bacterial and primary production in lakes.\n \n \n \n\n\n \n Ask, J.; Karlsson, J.; Persson, L.; Ask, P.; Byström, P.; and Jansson, M.\n\n\n \n\n\n\n Limnology and Oceanography, 54(6): 2034–2040. November 2009.\n \n\n\n\n
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\n\n\n@article{ask_terrestrial_2009,\n\ttitle = {Terrestrial organic matter and light penetration: {Effects} on bacterial and primary production in lakes},\n\tvolume = {54},\n\tissn = {0024-3590},\n\tshorttitle = {Terrestrial organic matter and light penetration},\n\tdoi = {10.4319/lo.2009.54.6.2034},\n\tabstract = {We investigated productivity at the basal trophic level in 15 unproductive lakes in a gradient ranging from clear-water to brown-water (humic) lakes in northern Sweden. Primary production and bacterial production in benthic and pelagic habitats were measured to estimate the variation in energy mobilization from external energy sources (primary production plus bacterial production on allochthonous organic carbon) along the gradient. Clear-water lakes were dominated by autotrophic energy mobilization in the benthic habitat, whereas humic lakes were dominated by heterotrophic energy mobilization in the pelagic habitat. Whole-lake (benthic + pelagic) energy mobilization was negatively correlated to the light-extinction coefficient, which was determined by colored terrestrial organic matter in the lake water. Thus, variation in the concentration of terrestrial organic matter and its light-absorbing characteristics exerts strong control on the magnitude, as well as on the processes and pathways, of energy mobilization in unproductive lakes. We suggest that unproductive lakes in general are sensitive to input of terrestrial organic matter because of its effects on basal energy mobilization in both benthic and pelagic habitats.},\n\tlanguage = {English},\n\tnumber = {6},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Ask, Jenny and Karlsson, Jan and Persson, Lennart and Ask, Per and Byström, Pär and Jansson, Mats},\n\tmonth = nov,\n\tyear = {2009},\n\tkeywords = {\\#nosource, altitude gradient, benthic pathways, carbon, clear-water lakes, humic lakes, loch ness, northern sweden, nutrient limitation, pelagic food webs, phytoplankton},\n\tpages = {2034--2040},\n}\n\n\n\n\n\n We investigated productivity at the basal trophic level in 15 unproductive lakes in a gradient ranging from clear-water to brown-water (humic) lakes in northern Sweden. Primary production and bacterial production in benthic and pelagic habitats were measured to estimate the variation in energy mobilization from external energy sources (primary production plus bacterial production on allochthonous organic carbon) along the gradient. Clear-water lakes were dominated by autotrophic energy mobilization in the benthic habitat, whereas humic lakes were dominated by heterotrophic energy mobilization in the pelagic habitat. Whole-lake (benthic + pelagic) energy mobilization was negatively correlated to the light-extinction coefficient, which was determined by colored terrestrial organic matter in the lake water. Thus, variation in the concentration of terrestrial organic matter and its light-absorbing characteristics exerts strong control on the magnitude, as well as on the processes and pathways, of energy mobilization in unproductive lakes. We suggest that unproductive lakes in general are sensitive to input of terrestrial organic matter because of its effects on basal energy mobilization in both benthic and pelagic habitats.\n
\n\n\n\n \n\n \n \n \n \n \n \n Are autochthonous foods more important than allochthonous resources to benthic consumers in tropical headwater streams?.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n Journal of the North American Benthological Society, 28(2): 426–439. April 2009.\n \n\n\n\n
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\n\n\n@article{lau_are_2009,\n\ttitle = {Are autochthonous foods more important than allochthonous resources to benthic consumers in tropical headwater streams?},\n\tvolume = {28},\n\tissn = {0887-3593},\n\turl = {http://www.bioone.org/doi/abs/10.1899/07-079.1},\n\tdoi = {10.1899/07-079.1},\n\tabstract = {Increasing evidence suggests that autochthonous foods are the principal basis of consumer production in tropical forest streams, despite the predominance of terrestrial detritus inputs. The relative importance of autochthonous and allochthonous energy for the dominant benthic consumers was investigated in 3 tropical headwater streams with different shading conditions in Hong Kong with a combination of assimilation-based analyses: stoichiometry, C and N stable isotopes, and fatty acid (FA) profiling. The snail Brotia hainanensis (Pachychilidae), shrimps Caridina cantonensis (Atyidae) and Macrobrachium hainanense (Palaemonidae), and their potential basal food sources (leaf litter, fine particulate organic matter [FPOM], periphyton, cyanobacteria, and filamentous algae) were collected in Tai Po Kau Forest Stream (shaded 1), Shing Mun Stream (shaded 2), and Pak Ngau Shek Stream (open) during the 2004 dry season (January and February). All samples were analyzed for C:N ratios, δ13C, and δ15N values. Total FAs were extracted from each sample, and concentrations of 35 important FAs were analyzed by gas chromatography–mass spectrometry (GC–MS). C:N ratios of algal foods were markedly lower than those of terrestrial detritus and similar to those of the test animals at all 3 sites, a result that suggested that autochthonous sources were relatively more nutritious than were allochthonous sources. Autochthonous foods were more 13C and 15N enriched than were allochthonous foods at all sites. The algal sources contributed to 29 to 98\\% of consumer biomass, generally more than was attributed to the terrestrial sources (2–71\\%). Consumers also showed distinctive FA profiles indicating consumption of autochthonous foods, especially periphytic diatoms and cyanobacteria, as revealed by the elevated concentrations of FA biomarkers such as palmitoleic (16:1[cis-9]) and eicosapentaenoic acids (20:5[all cis-5,8,11,14,17]) in the consumers, periphyton, and cyanobacteria. Our results suggest that autochthonous resources are possibly more important than allochthonous foods to secondary production in tropical headwater streams.},\n\tnumber = {2},\n\turldate = {2017-05-27},\n\tjournal = {Journal of the North American Benthological Society},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y. and Dudgeon, David},\n\tmonth = apr,\n\tyear = {2009},\n\tkeywords = {\\#nosource},\n\tpages = {426--439},\n}\n\n\n\n\n\n Increasing evidence suggests that autochthonous foods are the principal basis of consumer production in tropical forest streams, despite the predominance of terrestrial detritus inputs. The relative importance of autochthonous and allochthonous energy for the dominant benthic consumers was investigated in 3 tropical headwater streams with different shading conditions in Hong Kong with a combination of assimilation-based analyses: stoichiometry, C and N stable isotopes, and fatty acid (FA) profiling. The snail Brotia hainanensis (Pachychilidae), shrimps Caridina cantonensis (Atyidae) and Macrobrachium hainanense (Palaemonidae), and their potential basal food sources (leaf litter, fine particulate organic matter [FPOM], periphyton, cyanobacteria, and filamentous algae) were collected in Tai Po Kau Forest Stream (shaded 1), Shing Mun Stream (shaded 2), and Pak Ngau Shek Stream (open) during the 2004 dry season (January and February). All samples were analyzed for C:N ratios, δ13C, and δ15N values. Total FAs were extracted from each sample, and concentrations of 35 important FAs were analyzed by gas chromatography–mass spectrometry (GC–MS). C:N ratios of algal foods were markedly lower than those of terrestrial detritus and similar to those of the test animals at all 3 sites, a result that suggested that autochthonous sources were relatively more nutritious than were allochthonous sources. Autochthonous foods were more 13C and 15N enriched than were allochthonous foods at all sites. The algal sources contributed to 29 to 98% of consumer biomass, generally more than was attributed to the terrestrial sources (2–71%). Consumers also showed distinctive FA profiles indicating consumption of autochthonous foods, especially periphytic diatoms and cyanobacteria, as revealed by the elevated concentrations of FA biomarkers such as palmitoleic (16:1[cis-9]) and eicosapentaenoic acids (20:5[all cis-5,8,11,14,17]) in the consumers, periphyton, and cyanobacteria. Our results suggest that autochthonous resources are possibly more important than allochthonous foods to secondary production in tropical headwater streams.\n
\n\n\n\n \n\n \n \n \n \n \n \n Evidence of rapid shifts in the trophic base of lotic predators using experimental dietary manipulations and assimilation-based analyses.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n Oecologia, 159(4): 767–776. April 2009.\n 00019\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{lau_evidence_2009,\n\ttitle = {Evidence of rapid shifts in the trophic base of lotic predators using experimental dietary manipulations and assimilation-based analyses},\n\tvolume = {159},\n\tissn = {0029-8549, 1432-1939},\n\turl = {https://link.springer.com/article/10.1007/s00442-008-1262-0},\n\tdoi = {10.1007/s00442-008-1262-0},\n\tabstract = {Assimilation-based techniques such as stoichiometric analysis, bulk tissue stable isotope analysis (SIA), fatty acid (FA) profiling and compound-specific SIA of FAs can be used to resolve ambiguities in consumer-resource relationships, but comparisons of their effectiveness are lacking. Feeding trials and concurrent application of these techniques were used to investigate the trophic base of two shrimps from Hong Kong streams: the atyid Caridina cantonensis, which is a primary consumer, and predatory Macrobrachium hainanense (Palaemonidae). Leaf litter and periphyton were fed to C. cantonensis (CC-LF and CC-PF, respectively) reared in the laboratory for 2 months, when C. cantonensis, that had fed on a mixed diet (CC-WC), were collected from the field. Atyids from each group (CC-LF, CC-PF and CC-WC) were fed to M. hainanense (MH-L, MH-P and MH-W, respectively) during a further 2-month trial, at the end of which M. hainanense were also collected from the field (MH-R). FA biomarkers present in CC-WC and CC-PF indicated that C. cantonensis depended primarily on autochthonous foods, and FA profiles of CC-WC were distinct from those of CC-LF. Differences in C/N ratios and isotope signatures of leaf litter and periphyton were not reflected in tissues of atyids or palaemonid predators. FA profiles of M. hainanense groups were similar, but FA stable C isotope ratio (δ13C) signatures of MH-R and MH-W were distinct from those of MH-L and leaf litter. FA δ13C signatures of MH-R were similar to those of MH-P and MH-W, indicating that autochthonous resources constituted the trophic base of production for this predator. This is the first study using compound-specific SIA to study stream food chains. Compound-specific SIA and FA profiling allowed accurate elucidation of consumer-resource relationships that were not revealed by stoichiometry or bulk tissue SIA. Compound-specific SIA was particularly sensitive for detecting rapid shifts in the predator trophic base. This tool will have wide applicability for investigating food webs in a range of ecosystems.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-05-27},\n\tjournal = {Oecologia},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y. and Dudgeon, David},\n\tmonth = apr,\n\tyear = {2009},\n\tnote = {00019},\n\tkeywords = {\\#nosource},\n\tpages = {767--776},\n}\n\n\n\n\n\n Assimilation-based techniques such as stoichiometric analysis, bulk tissue stable isotope analysis (SIA), fatty acid (FA) profiling and compound-specific SIA of FAs can be used to resolve ambiguities in consumer-resource relationships, but comparisons of their effectiveness are lacking. Feeding trials and concurrent application of these techniques were used to investigate the trophic base of two shrimps from Hong Kong streams: the atyid Caridina cantonensis, which is a primary consumer, and predatory Macrobrachium hainanense (Palaemonidae). Leaf litter and periphyton were fed to C. cantonensis (CC-LF and CC-PF, respectively) reared in the laboratory for 2 months, when C. cantonensis, that had fed on a mixed diet (CC-WC), were collected from the field. Atyids from each group (CC-LF, CC-PF and CC-WC) were fed to M. hainanense (MH-L, MH-P and MH-W, respectively) during a further 2-month trial, at the end of which M. hainanense were also collected from the field (MH-R). FA biomarkers present in CC-WC and CC-PF indicated that C. cantonensis depended primarily on autochthonous foods, and FA profiles of CC-WC were distinct from those of CC-LF. Differences in C/N ratios and isotope signatures of leaf litter and periphyton were not reflected in tissues of atyids or palaemonid predators. FA profiles of M. hainanense groups were similar, but FA stable C isotope ratio (δ13C) signatures of MH-R and MH-W were distinct from those of MH-L and leaf litter. FA δ13C signatures of MH-R were similar to those of MH-P and MH-W, indicating that autochthonous resources constituted the trophic base of production for this predator. This is the first study using compound-specific SIA to study stream food chains. Compound-specific SIA and FA profiling allowed accurate elucidation of consumer-resource relationships that were not revealed by stoichiometry or bulk tissue SIA. Compound-specific SIA was particularly sensitive for detecting rapid shifts in the predator trophic base. This tool will have wide applicability for investigating food webs in a range of ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Soil carbon accumulation in the dry tundra: Important role played by precipitation.\n \n \n \n \n\n\n \n Klaminder, J.; Yoo, K.; and Giesler, R.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 114(G4): G04005. December 2009.\n \n\n\n\n
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\n\n\n@article{klaminder_soil_2009,\n\ttitle = {Soil carbon accumulation in the dry tundra: {Important} role played by precipitation},\n\tvolume = {114},\n\tissn = {2156-2202},\n\tshorttitle = {Soil carbon accumulation in the dry tundra},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2009JG000947/abstract},\n\tdoi = {10.1029/2009JG000947},\n\tabstract = {A positive relationship between the mean annual precipitation (MAP) and soil organic carbon (SOC) is found in most surveys covering the subarctic and boreal region. In this paper we assess mechanisms behind variable SOC pools in dry tundra soils developed along a 50 km long subarctic precipitation (snow) gradient in northern Sweden. Lead 210 is used to infer SOC accumulation rates in the O horizon. Despite an unchanged or even slightly decreasing accumulation rate of SOC in the O horizon (range 0.02–0.06 kg C m−2 yr−1) along with increasing MAP and a relative constant litter input (∼0.04 kg C m−2 yr−1), the SOC pool in the upper 1 m increase significantly with increasing MAP. This trend is mainly due to a progressively buildup of SOC in the mineral soil and argued to be the result of an accelerated vertical translocation of SOC at sites overlain by a thick snowpack. Furthermore, the loss of SOC from the O horizon through wind erosion appears to be more pronounced at snow-poor sites. We estimate that vegetated heath soil may loose {\\textgreater}0.02 kg C m−2 yr−1 (∼half of the annual litter fall) due to wind erosion in snow-poor areas. We stress that lateral and vertical translocation processes inherent by precipitation regimes may be of fundamental importance for the long-term SOC accumulation in tundra soil.},\n\tlanguage = {en},\n\tnumber = {G4},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Klaminder, Jonatan and Yoo, Kyungsoo and Giesler, Reiner},\n\tmonth = dec,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Biogeochemical cycles, processes, and modeling, Pb-210, Permafrost, cryosphere, and high-latitude processes, carbon, carbon cycling, tundra},\n\tpages = {G04005},\n}\n\n\n\n\n\n A positive relationship between the mean annual precipitation (MAP) and soil organic carbon (SOC) is found in most surveys covering the subarctic and boreal region. In this paper we assess mechanisms behind variable SOC pools in dry tundra soils developed along a 50 km long subarctic precipitation (snow) gradient in northern Sweden. Lead 210 is used to infer SOC accumulation rates in the O horizon. Despite an unchanged or even slightly decreasing accumulation rate of SOC in the O horizon (range 0.02–0.06 kg C m−2 yr−1) along with increasing MAP and a relative constant litter input (∼0.04 kg C m−2 yr−1), the SOC pool in the upper 1 m increase significantly with increasing MAP. This trend is mainly due to a progressively buildup of SOC in the mineral soil and argued to be the result of an accelerated vertical translocation of SOC at sites overlain by a thick snowpack. Furthermore, the loss of SOC from the O horizon through wind erosion appears to be more pronounced at snow-poor sites. We estimate that vegetated heath soil may loose \\textgreater0.02 kg C m−2 yr−1 (∼half of the annual litter fall) due to wind erosion in snow-poor areas. We stress that lateral and vertical translocation processes inherent by precipitation regimes may be of fundamental importance for the long-term SOC accumulation in tundra soil.\n
\n\n\n\n \n\n \n \n \n \n \n \n Herbivores inhibit climate-driven shrub expansion on the tundra.\n \n \n \n \n\n\n \n Olofsson, J.; Oksanen, L.; Callaghan, T.; Hulme, P. E.; Oksanen, T.; and Suominen, O.\n\n\n \n\n\n\n Global Change Biology, 15(11): 2681–2693. November 2009.\n \n\n\n\n
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\n\n\n@article{olofsson_herbivores_2009,\n\ttitle = {Herbivores inhibit climate-driven shrub expansion on the tundra},\n\tvolume = {15},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.01935.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2009.01935.x},\n\tabstract = {Recent Pan-Arctic shrub expansion has been interpreted as a response to a warmer climate. However, herbivores can also influence the abundance of shrubs in arctic ecosystems. We addressed these alternative explanations by following the changes in plant community composition during the last 10 years in permanent plots inside and outside exclosures with different mesh sizes that exclude either only reindeer or all mammalian herbivores including voles and lemmings. The exclosures were replicated at three forest and tundra sites at four different locations along a climatic gradient (oceanic to continental) in northern Fennoscandia. Since the last 10 years have been exceptionally warm, we could study how warming has influenced the vegetation in different grazing treatments. Our results show that the abundance of the dominant shrub, Betula nana, has increased during the last decade, but that the increase was more pronounced when herbivores were excluded. Reindeer have the largest effect on shrubs in tundra, while voles and lemmings have a larger effect in the forest. The positive relationship between annual mean temperature and shrub growth in the absence of herbivores and the lack of relationships in grazed controls is another indication that shrub abundance is controlled by an interaction between herbivores and climate. In addition to their effects on taller shrubs ({\\textgreater}0.3 m), reindeer reduced the abundance of lichens, whereas microtine rodents reduced the abundance of dwarf shrubs ({\\textless}0.3 m) and mosses. In contrast to short-term responses, competitive interactions between dwarf shrubs and lichens were evident in the long term. These results show that herbivores have to be considered in order to understand how a changing climate will influence tundra ecosystems.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Olofsson, Johan and Oksanen, Lauri and Callaghan, Terry and Hulme, Philip E. and Oksanen, Tarja and Suominen, Otso},\n\tmonth = nov,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Betula nana, exclosures, global warming, herbivores, lemmings, reindeer, shrubs, snow, tundra, voles},\n\tpages = {2681--2693},\n}\n\n\n\n\n\n Recent Pan-Arctic shrub expansion has been interpreted as a response to a warmer climate. However, herbivores can also influence the abundance of shrubs in arctic ecosystems. We addressed these alternative explanations by following the changes in plant community composition during the last 10 years in permanent plots inside and outside exclosures with different mesh sizes that exclude either only reindeer or all mammalian herbivores including voles and lemmings. The exclosures were replicated at three forest and tundra sites at four different locations along a climatic gradient (oceanic to continental) in northern Fennoscandia. Since the last 10 years have been exceptionally warm, we could study how warming has influenced the vegetation in different grazing treatments. Our results show that the abundance of the dominant shrub, Betula nana, has increased during the last decade, but that the increase was more pronounced when herbivores were excluded. Reindeer have the largest effect on shrubs in tundra, while voles and lemmings have a larger effect in the forest. The positive relationship between annual mean temperature and shrub growth in the absence of herbivores and the lack of relationships in grazed controls is another indication that shrub abundance is controlled by an interaction between herbivores and climate. In addition to their effects on taller shrubs (\\textgreater0.3 m), reindeer reduced the abundance of lichens, whereas microtine rodents reduced the abundance of dwarf shrubs (\\textless0.3 m) and mosses. In contrast to short-term responses, competitive interactions between dwarf shrubs and lichens were evident in the long term. These results show that herbivores have to be considered in order to understand how a changing climate will influence tundra ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Arctic alpine vegetation change over 20 years.\n \n \n \n \n\n\n \n Wilson, S. D.; and Nilsson, C.\n\n\n \n\n\n\n Global Change Biology, 15(7): 1676–1684. July 2009.\n \n\n\n\n
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\n\n\n@article{wilson_arctic_2009,\n\ttitle = {Arctic alpine vegetation change over 20 years},\n\tvolume = {15},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.01896.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2009.01896.x},\n\tabstract = {Recent arctic warming experiments have recorded significant vegetation responses, typically an increase in shrub cover and a loss of species richness. We report similar changes in vegetation along an arctic mountainside in northern Sweden over 20 years. During this time mean annual temperature increased by 2.0 °C, and growing season temperature by 2.3 °C. Growing season length increased by 28\\% at the bottom of our study area, in birch forest, and by 175\\% on the mountaintop. Neither total vegetation cover nor the cover of bare ground changed. One common dwarf shrub, Empetrum hermaphroditum, and two common forbs, Viola biflora and Geranium sylvaticum, increased in abundance over time, but no common species moved up the gradient. Species richness declined significantly over time, with an average loss of two species per 50 cm × 100 cm plot. The richness of herbaceous species at intermediate altitudes decreased significantly with increasing shrub cover. In spite of large changes in temperature, the type and magnitude of vegetation change along this mountainside were relatively modest and consistent with those from wide-spread warming experiments.},\n\tlanguage = {en},\n\tnumber = {7},\n\turldate = {2017-02-07},\n\tjournal = {Global Change Biology},\n\tauthor = {Wilson, Scott D. and Nilsson, Christer},\n\tmonth = jul,\n\tyear = {2009},\n\tkeywords = {\\#nosource, climate change, competition, diversity, gradient, growing season length, growth form, homeostasis, shrub, warming experiments},\n\tpages = {1676--1684},\n}\n\n\n\n\n\n Recent arctic warming experiments have recorded significant vegetation responses, typically an increase in shrub cover and a loss of species richness. We report similar changes in vegetation along an arctic mountainside in northern Sweden over 20 years. During this time mean annual temperature increased by 2.0 °C, and growing season temperature by 2.3 °C. Growing season length increased by 28% at the bottom of our study area, in birch forest, and by 175% on the mountaintop. Neither total vegetation cover nor the cover of bare ground changed. One common dwarf shrub, Empetrum hermaphroditum, and two common forbs, Viola biflora and Geranium sylvaticum, increased in abundance over time, but no common species moved up the gradient. Species richness declined significantly over time, with an average loss of two species per 50 cm × 100 cm plot. The richness of herbaceous species at intermediate altitudes decreased significantly with increasing shrub cover. In spite of large changes in temperature, the type and magnitude of vegetation change along this mountainside were relatively modest and consistent with those from wide-spread warming experiments.\n
\n\n\n\n \n\n \n \n \n \n \n \n High resilience in the Yamal-Nenets social–ecological system, West Siberian Arctic, Russia.\n \n \n \n \n\n\n \n Forbes, B. C.; Stammler, F.; Kumpula, T.; Meschtyb, N.; Pajunen, A.; and Kaarlejärvi, E.\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences, 106(52): 22041–22048. December 2009.\n \n\n\n\n
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\n\n\n@article{forbes_high_2009,\n\ttitle = {High resilience in the {Yamal}-{Nenets} social–ecological system, {West} {Siberian} {Arctic}, {Russia}},\n\tvolume = {106},\n\tissn = {0027-8424, 1091-6490},\n\turl = {http://www.pnas.org/content/106/52/22041},\n\tdoi = {10.1073/pnas.0908286106},\n\tabstract = {Tundra ecosystems are vulnerable to hydrocarbon development, in part because small-scale, low-intensity disturbances can affect vegetation, permafrost soils, and wildlife out of proportion to their spatial extent. Scaling up to include human residents, tightly integrated arctic social-ecological systems (SESs) are believed similarly susceptible to industrial impacts and climate change. In contrast to northern Alaska and Canada, most terrestrial and aquatic components of West Siberian oil and gas fields are seasonally exploited by migratory herders, hunters, fishers, and domesticated reindeer (Rangifer tarandus L.). Despite anthropogenic fragmentation and transformation of a large proportion of the environment, recent socioeconomic upheaval, and pronounced climate warming, we find the Yamal-Nenets SES highly resilient according to a few key measures. We detail the remarkable extent to which the system has successfully reorganized in response to recent shocks and evaluate the limits of the system's capacity to respond. Our analytical approach combines quantitative methods with participant observation to understand the overall effects of rapid land use and climate change at the level of the entire Yamal system, detect thresholds crossed using surrogates, and identify potential traps. Institutional constraints and drivers were as important as the documented ecological changes. Particularly crucial to success is the unfettered movement of people and animals in space and time, which allows them to alternately avoid or exploit a wide range of natural and anthropogenic habitats. However, expansion of infrastructure, concomitant terrestrial and freshwater ecosystem degradation, climate change, and a massive influx of workers underway present a looming threat to future resilience.},\n\tlanguage = {en},\n\tnumber = {52},\n\turldate = {2017-02-08},\n\tjournal = {Proceedings of the National Academy of Sciences},\n\tauthor = {Forbes, Bruce C. and Stammler, Florian and Kumpula, Timo and Meschtyb, Nina and Pajunen, Anu and Kaarlejärvi, Elina},\n\tmonth = dec,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Rangifer tarandus, oil and gas activities, reindeer nomadism, remote sensing, tundra disturbance},\n\tpages = {22041--22048},\n}\n\n\n\n\n\n Tundra ecosystems are vulnerable to hydrocarbon development, in part because small-scale, low-intensity disturbances can affect vegetation, permafrost soils, and wildlife out of proportion to their spatial extent. Scaling up to include human residents, tightly integrated arctic social-ecological systems (SESs) are believed similarly susceptible to industrial impacts and climate change. In contrast to northern Alaska and Canada, most terrestrial and aquatic components of West Siberian oil and gas fields are seasonally exploited by migratory herders, hunters, fishers, and domesticated reindeer (Rangifer tarandus L.). Despite anthropogenic fragmentation and transformation of a large proportion of the environment, recent socioeconomic upheaval, and pronounced climate warming, we find the Yamal-Nenets SES highly resilient according to a few key measures. We detail the remarkable extent to which the system has successfully reorganized in response to recent shocks and evaluate the limits of the system's capacity to respond. Our analytical approach combines quantitative methods with participant observation to understand the overall effects of rapid land use and climate change at the level of the entire Yamal system, detect thresholds crossed using surrogates, and identify potential traps. Institutional constraints and drivers were as important as the documented ecological changes. Particularly crucial to success is the unfettered movement of people and animals in space and time, which allows them to alternately avoid or exploit a wide range of natural and anthropogenic habitats. However, expansion of infrastructure, concomitant terrestrial and freshwater ecosystem degradation, climate change, and a massive influx of workers underway present a looming threat to future resilience.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of a warmer climate on seed germination in the subarctic.\n \n \n \n \n\n\n \n Milbau, A.; Graae, B. J.; Shevtsova, A.; and Nijs, I.\n\n\n \n\n\n\n Annals of Botany, 104(2): 287–296. August 2009.\n \n\n\n\n
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\n\n\n@article{milbau_effects_2009,\n\ttitle = {Effects of a warmer climate on seed germination in the subarctic},\n\tvolume = {104},\n\tissn = {0305-7364, 1095-8290},\n\turl = {http://aob.oxfordjournals.org.proxy.ub.umu.se/content/104/2/287},\n\tdoi = {10.1093/aob/mcp117},\n\tabstract = {Background and Aims In a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. Because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined.\nMethods Under controlled conditions, how colder winter and warmer summer soil temperatures influenced germination was tested in 23 subarctic species. The cold stratification and warm incubation temperatures were derived from real soil temperature measurements in subarctic tundra and the temperatures were gradually changed over time to simulate different months of the year.\nKey Results Moderate summer warming (+2·5 °C) substantially accelerated germination in all but four species but did not affect germination percentages. Optimum germination temperatures (20/10°C) further decreased germination time and increased germination percentages in three species. Colder winter soil temperatures delayed the germination in ten species and decreased the germination percentage in four species, whereas the opposite was found in Silene acaulis. In most species, the combined effect of a reduced snow cover and summer warming resulted in earlier germination and thus a longer first growing season, which improves the chance of seedling survival. In particular the recruitment of (dwarf) shrubs (Vaccinium myrtillus, V. vitis-idaea, Betula nana), trees (Alnus incana, Betula pubescens) and grasses (Calamagrostis lapponica, C. purpurea) is likely to benefit from a warmer subarctic climate.\nConclusions Seedling establishment is expected to improve in a future warmer subarctic climate, mainly by considerably earlier germination. The magnitudes of the responses are species-specific, which should be taken into account when modelling population growth and migration of subarctic species.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2016-11-08},\n\tjournal = {Annals of Botany},\n\tauthor = {Milbau, Ann and Graae, Bente Jessen and Shevtsova, Anna and Nijs, Ivan},\n\tmonth = aug,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Silene, Vaccinium, Warming, climate change, cold stratification, dwarf shrubs, germination percentage, incubation temperature, mean germination time, seedling establishment, seeds, subarctic species},\n\tpages = {287--296},\n}\n\n\n\n\n\n Background and Aims In a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. Because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined. Methods Under controlled conditions, how colder winter and warmer summer soil temperatures influenced germination was tested in 23 subarctic species. The cold stratification and warm incubation temperatures were derived from real soil temperature measurements in subarctic tundra and the temperatures were gradually changed over time to simulate different months of the year. Key Results Moderate summer warming (+2·5 °C) substantially accelerated germination in all but four species but did not affect germination percentages. Optimum germination temperatures (20/10°C) further decreased germination time and increased germination percentages in three species. Colder winter soil temperatures delayed the germination in ten species and decreased the germination percentage in four species, whereas the opposite was found in Silene acaulis. In most species, the combined effect of a reduced snow cover and summer warming resulted in earlier germination and thus a longer first growing season, which improves the chance of seedling survival. In particular the recruitment of (dwarf) shrubs (Vaccinium myrtillus, V. vitis-idaea, Betula nana), trees (Alnus incana, Betula pubescens) and grasses (Calamagrostis lapponica, C. purpurea) is likely to benefit from a warmer subarctic climate. Conclusions Seedling establishment is expected to improve in a future warmer subarctic climate, mainly by considerably earlier germination. The magnitudes of the responses are species-specific, which should be taken into account when modelling population growth and migration of subarctic species.\n
\n\n\n\n \n\n \n \n \n \n \n Trampling and Spatial Heterogeneity Explain Decomposer Abundances in a Sub-Arctic Grassland Subjected to Simulated Reindeer Grazing.\n \n \n \n\n\n \n Sorensen, L. I.; Mikola, J.; Kytoviita, M.; and Olofsson, J.\n\n\n \n\n\n\n Ecosystems, 12(5): 830–842. August 2009.\n \n\n\n\n
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\n\n\n@article{sorensen_trampling_2009,\n\ttitle = {Trampling and {Spatial} {Heterogeneity} {Explain} {Decomposer} {Abundances} in a {Sub}-{Arctic} {Grassland} {Subjected} to {Simulated} {Reindeer} {Grazing}},\n\tvolume = {12},\n\tissn = {1432-9840},\n\tdoi = {10.1007/s10021-009-9260-6},\n\tabstract = {Mammal grazing is composed of three mechanisms-removal of foliar tissue (defoliation), return of nutrients via dung and urine (fertilization), and trampling. To evaluate the relative role of these mechanisms in the effect of reindeer grazing on soil biota in northern grasslands, we subjected experimental plots in a sub-arctic alpine meadow to defoliation, fertilization (using NPK-solution), simulated trampling, and their factorial combinations once a year from 2002 to 2004 and measured the response of plants and decomposers (including microbes, nematodes, collembolans, and enchytraeids) in 2004. Trampling affected both plant and decomposer communities: the coverage of the moss Pleurozium schreberi and the sedge Carex vaginata, as well as the abundance of collembolans and enchytraeids were reduced in trampled plots. Trampling and fertilization also interacted significantly, with fertilization increasing the abundance of bacteria and bacterial-feeding and omnivorous nematodes in trampled plots only, and trampling decreasing fungal biomass in non-fertilized plots only. Defoliation had no overall effects on plants or decomposers. Nematode genera were not affected by the experimental treatments, but nematode and plant communities were significantly associated, and all decomposer biota, except collembolans, were strongly affected by the spatial heterogeneity of the study site. Our results indicate that trampling may have larger and defoliation and fertilization smaller roles than anticipated in explaining reindeer grazing effects in sub-arctic grasslands. However, even the effects of trampling seem to be outweighed by the spatial heterogeneity of decomposer abundances. This suggests that in sub-arctic grasslands spatial variation in abiotic factors can be a more important factor than grazing in controlling soil biota abundances.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Ecosystems},\n\tauthor = {Sorensen, Louise Ilum and Mikola, Juha and Kytoviita, Minna-Maarit and Olofsson, Johan},\n\tmonth = aug,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Spatial heterogeneity, abiotic factors, animal trophic groups, cold climate, collembolan, enchytraeid, fertilization, food-web, mountain birch forests, nematode, nitrogen mineralization, organic-compounds, plant community, repeated defoliation, soil biota, soil microbial responses, species composition, tundra ecosystems, yellowstone-national-park},\n\tpages = {830--842},\n}\n\n\n\n\n\n Mammal grazing is composed of three mechanisms-removal of foliar tissue (defoliation), return of nutrients via dung and urine (fertilization), and trampling. To evaluate the relative role of these mechanisms in the effect of reindeer grazing on soil biota in northern grasslands, we subjected experimental plots in a sub-arctic alpine meadow to defoliation, fertilization (using NPK-solution), simulated trampling, and their factorial combinations once a year from 2002 to 2004 and measured the response of plants and decomposers (including microbes, nematodes, collembolans, and enchytraeids) in 2004. Trampling affected both plant and decomposer communities: the coverage of the moss Pleurozium schreberi and the sedge Carex vaginata, as well as the abundance of collembolans and enchytraeids were reduced in trampled plots. Trampling and fertilization also interacted significantly, with fertilization increasing the abundance of bacteria and bacterial-feeding and omnivorous nematodes in trampled plots only, and trampling decreasing fungal biomass in non-fertilized plots only. Defoliation had no overall effects on plants or decomposers. Nematode genera were not affected by the experimental treatments, but nematode and plant communities were significantly associated, and all decomposer biota, except collembolans, were strongly affected by the spatial heterogeneity of the study site. Our results indicate that trampling may have larger and defoliation and fertilization smaller roles than anticipated in explaining reindeer grazing effects in sub-arctic grasslands. However, even the effects of trampling seem to be outweighed by the spatial heterogeneity of decomposer abundances. This suggests that in sub-arctic grasslands spatial variation in abiotic factors can be a more important factor than grazing in controlling soil biota abundances.\n
\n\n\n\n \n\n \n \n \n \n \n A hierarchical framework for integrating invasibility experiments incorporating different factors and spatial scales.\n \n \n \n\n\n \n Milbau, A.; Stout, J. C.; Graae, B. J.; and Nijs, I.\n\n\n \n\n\n\n Biological Invasions, 11(4): 941–950. April 2009.\n \n\n\n\n
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\n\n\n@article{milbau_hierarchical_2009,\n\ttitle = {A hierarchical framework for integrating invasibility experiments incorporating different factors and spatial scales},\n\tvolume = {11},\n\tissn = {1387-3547},\n\tdoi = {10.1007/s10530-008-9306-2},\n\tabstract = {Results from experiments studying different factors determining invasibility (e.g. land use, disturbance, biotic interactions) at different spatial scales are mainly used in isolation, probably because a methodology for integration is lacking. Recent studies show that factors affecting invasibility most likely do so in a hierarchical manner, with different factors acting more strongly at different spatial scales. Climate can be considered the dominant factor at the continental scale, while at regional and landscape scale topography, land cover and land use become increasingly important. At smaller spatial scales, soil type, disturbance, biotic interactions, resources, and microclimate may become significant. In the current paper, we propose a hierarchical framework for combining results from different types of studies. In this hierarchical system, factors operating at a smaller scale are subordinate to factors operating at a larger scale, but if conditions at higher levels are satisfied, the small-scale factors may become indispensable for making accurate predictions. Depending on the aim of the study, the accuracy of prediction can be selected by the researcher, which in its turn determines which data are required. We discuss several applications of the framework and indicate some options for future research. Although the complexity of natural systems presents fundamental limits to predictions, we think this framework can provide a useful tool for the identification of areas of risk for biological invasions, for improving our understanding of invasibility, and for identifying gaps in our current knowledge.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Biological Invasions},\n\tauthor = {Milbau, Ann and Stout, Jane C. and Graae, Bente J. and Nijs, Ivan},\n\tmonth = apr,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Hierarchical framework, Integration, Spatial scale, alien plant invasions, biological invasions, central chile, climate-change, environmental gradients, exotic shrub, impatiens-glandulifera, invasibility, land-use, new-zealand, plant invasion, species-diversity},\n\tpages = {941--950},\n}\n\n\n\n\n\n Results from experiments studying different factors determining invasibility (e.g. land use, disturbance, biotic interactions) at different spatial scales are mainly used in isolation, probably because a methodology for integration is lacking. Recent studies show that factors affecting invasibility most likely do so in a hierarchical manner, with different factors acting more strongly at different spatial scales. Climate can be considered the dominant factor at the continental scale, while at regional and landscape scale topography, land cover and land use become increasingly important. At smaller spatial scales, soil type, disturbance, biotic interactions, resources, and microclimate may become significant. In the current paper, we propose a hierarchical framework for combining results from different types of studies. In this hierarchical system, factors operating at a smaller scale are subordinate to factors operating at a larger scale, but if conditions at higher levels are satisfied, the small-scale factors may become indispensable for making accurate predictions. Depending on the aim of the study, the accuracy of prediction can be selected by the researcher, which in its turn determines which data are required. We discuss several applications of the framework and indicate some options for future research. Although the complexity of natural systems presents fundamental limits to predictions, we think this framework can provide a useful tool for the identification of areas of risk for biological invasions, for improving our understanding of invasibility, and for identifying gaps in our current knowledge.\n
\n\n\n\n \n\n \n \n \n \n \n Effects of Simulated Reindeer Grazing, Trampling, and Waste Products on Nitrogen Mineralization and Primary Production.\n \n \n \n\n\n \n Olofsson, J.\n\n\n \n\n\n\n Arctic Antarctic and Alpine Research, 41(3): 330–338. August 2009.\n \n\n\n\n
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\n\n\n@article{olofsson_effects_2009,\n\ttitle = {Effects of {Simulated} {Reindeer} {Grazing}, {Trampling}, and {Waste} {Products} on {Nitrogen} {Mineralization} and {Primary} {Production}},\n\tvolume = {41},\n\tissn = {1523-0430},\n\tdoi = {10.1657/1938-4246-41.3.330},\n\tabstract = {An experiment was conducted in arctic tundra to evaluate the role of reindeer grazing, trampling, and feces and urine deposition in nutrient turnover and primary production. Grazing was simulated by mowing. trampling by the impact of a wooden pole, and waste product deposition by the application of fertilizer. In the first year, aboveground primary production increased with simulated grazing in the fertilized plots and decreased with simulated grazing in the unfertilized plots; this indicates a higher regrowth capacity at higher nutrient levels. However, nitrogen mineralization and primary production were mainly determined by the input or removal of nutrients and, therefore, decreased in plots that were grazed but not fertilized and increased in plots that were fertilized but not grazed. Simulated trampling decreased the depth of the moss layer and increased soil temperatures, but the higher temperatures increased N mineralization only in unmowed plots, and the increased nitrogen availability was not translated into increased primary production. Since aboveground and belowground net primary production in plots with simulated grazing was the same as in plots without simulated animal activity, this study indicates that an entire trophic level can be supported with no apparent effect on primary production.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Arctic Antarctic and Alpine Research},\n\tauthor = {Olofsson, Johan},\n\tmonth = aug,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Nutrient availability, arctic tundra heath, boreal forests, ecosystem processes, litter decomposition, microbial processes, plant-growth, salt-marsh, temperate grassland, yellowstone-national-park},\n\tpages = {330--338},\n}\n\n\n\n\n\n An experiment was conducted in arctic tundra to evaluate the role of reindeer grazing, trampling, and feces and urine deposition in nutrient turnover and primary production. Grazing was simulated by mowing. trampling by the impact of a wooden pole, and waste product deposition by the application of fertilizer. In the first year, aboveground primary production increased with simulated grazing in the fertilized plots and decreased with simulated grazing in the unfertilized plots; this indicates a higher regrowth capacity at higher nutrient levels. However, nitrogen mineralization and primary production were mainly determined by the input or removal of nutrients and, therefore, decreased in plots that were grazed but not fertilized and increased in plots that were fertilized but not grazed. Simulated trampling decreased the depth of the moss layer and increased soil temperatures, but the higher temperatures increased N mineralization only in unmowed plots, and the increased nitrogen availability was not translated into increased primary production. Since aboveground and belowground net primary production in plots with simulated grazing was the same as in plots without simulated animal activity, this study indicates that an entire trophic level can be supported with no apparent effect on primary production.\n
\n\n\n\n \n\n \n \n \n \n \n Increasing abundance of soil fungi is a driver for N-15 enrichment in soil profiles along a chronosequence undergoing isostatic rebound in northern Sweden.\n \n \n \n\n\n \n Wallander, H.; Morth, C.; and Giesler, R.\n\n\n \n\n\n\n Oecologia, 160(1): 87–96. May 2009.\n \n\n\n\n
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\n\n\n@article{wallander_increasing_2009,\n\ttitle = {Increasing abundance of soil fungi is a driver for {N}-15 enrichment in soil profiles along a chronosequence undergoing isostatic rebound in northern {Sweden}},\n\tvolume = {160},\n\tissn = {0029-8549},\n\tdoi = {10.1007/s00442-008-1270-0},\n\tabstract = {Soil organic material (SOM) is usually enriched in N-15 in deeper soil layers. This has been explained by discrimination against the heavier isotope during decomposition or by the accumulation of N-15-enriched microbial biomass versus plant biomass in older SOM. In particular, ectomycorrhizal (EM) fungi have been suggested to accumulate in old SOM since this group is among the most N-15-enriched components of the microbial community. In the present study we investigated the microbial community in soil samples along a chronosequence (7,800 years) of sites undergoing isostatic rebound in northern Sweden. The composition of the microbial community was analyzed and related to the delta N-15 and delta C-13 isotope values of the SOM in soil profiles. A significant change in the composition of the microbial community was found during the first 2,000 years, and this was positively related to an increase in the delta N-15 values of the E and B horizons in the mineral soil. The proportion of fungal phospholipid fatty acids increased with time in the chronosequence and was positively related to the N-15 enrichment of the SOM. The increase in delta C-13 in the SOM was much less than the increase in delta N-15, and delta C-13 values in the mineral soil were only weakly related to soil age. The C:N ratio and the pH of the soil were important factors determining the composition of the microbial community. We suggest that the N being transported from the soil to aboveground tissue by EM fungi is a driver for N-15 enrichment of soil profiles.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Oecologia},\n\tauthor = {Wallander, Hakan and Morth, Carl-Magnus and Giesler, Reiner},\n\tmonth = may,\n\tyear = {2009},\n\tkeywords = {\\#nosource, Chronosequence, Ectomycorrhizal fungi, Microbial community, Soil profile, ectomycorrhizal fungi, external mycelium, isotope fractionation, microbial communities, mycelia production, mycorrhizal fungi, natural-abundance, nitrogen deposition, organic-matter, plfa, primary succession},\n\tpages = {87--96},\n}\n\n\n\n\n\n Soil organic material (SOM) is usually enriched in N-15 in deeper soil layers. This has been explained by discrimination against the heavier isotope during decomposition or by the accumulation of N-15-enriched microbial biomass versus plant biomass in older SOM. In particular, ectomycorrhizal (EM) fungi have been suggested to accumulate in old SOM since this group is among the most N-15-enriched components of the microbial community. In the present study we investigated the microbial community in soil samples along a chronosequence (7,800 years) of sites undergoing isostatic rebound in northern Sweden. The composition of the microbial community was analyzed and related to the delta N-15 and delta C-13 isotope values of the SOM in soil profiles. A significant change in the composition of the microbial community was found during the first 2,000 years, and this was positively related to an increase in the delta N-15 values of the E and B horizons in the mineral soil. The proportion of fungal phospholipid fatty acids increased with time in the chronosequence and was positively related to the N-15 enrichment of the SOM. The increase in delta C-13 in the SOM was much less than the increase in delta N-15, and delta C-13 values in the mineral soil were only weakly related to soil age. The C:N ratio and the pH of the soil were important factors determining the composition of the microbial community. We suggest that the N being transported from the soil to aboveground tissue by EM fungi is a driver for N-15 enrichment of soil profiles.\n
\n\n\n\n \n\n \n \n \n \n \n \n Unravelling the effects of temperature, latitude and local environment on the reproduction of forest herbs.\n \n \n \n \n\n\n \n De Frenne, P.; Kolb, A.; Verheyen, K.; Brunet, J.; Chabrerie, O.; Decocq, G.; Diekmann, M.; Eriksson, O.; Heinken, T.; Hermy, M.; Jõgar, Ü.; Stanton, S.; Quataert, P.; Zindel, R.; Zobel, M.; and Graae, B. J.\n\n\n \n\n\n\n Global Ecology and Biogeography, 18(6): 641–651. November 2009.\n 00031\n\n\n\n
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\n\n\n@article{de_frenne_unravelling_2009,\n\ttitle = {Unravelling the effects of temperature, latitude and local environment on the reproduction of forest herbs},\n\tvolume = {18},\n\tissn = {1466-8238},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1466-8238.2009.00487.x/abstract},\n\tdoi = {10.1111/j.1466-8238.2009.00487.x},\n\tabstract = {Aim To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities. Location Six regions along a latitudinal gradient from France to Sweden. Methods Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number × seed mass, while germinable seed output (GSO) was expressed as seed number × germination percentage. We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO. Results Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge (Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species (Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior. Main conclusions We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2016-11-08},\n\tjournal = {Global Ecology and Biogeography},\n\tauthor = {De Frenne, P. and Kolb, A. and Verheyen, K. and Brunet, J. and Chabrerie, O. and Decocq, G. and Diekmann, M. and Eriksson, O. and Heinken, T. and Hermy, M. and Jõgar, Ü. and Stanton, S. and Quataert, P. and Zindel, R. and Zobel, M. and Graae, B. J.},\n\tmonth = nov,\n\tyear = {2009},\n\tnote = {00031},\n\tkeywords = {\\#nosource, Europe, climate change, herbaceous forest species, latitudinal gradient, reproduction, seeds, temperature},\n\tpages = {641--651},\n}\n\n\n\n\n\n Aim To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities. Location Six regions along a latitudinal gradient from France to Sweden. Methods Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number × seed mass, while germinable seed output (GSO) was expressed as seed number × germination percentage. We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO. Results Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge (Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species (Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior. Main conclusions We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of N : P loading ratios on phytoplankton community composition, primary production and N fixation in a eutrophic lake.\n \n \n \n \n\n\n \n Vrede, T.; Ballantyne, A.; Mille‐Lindblom, C.; Algesten, G.; Gudasz, C.; Lindahl, S.; and Brunberg, A. K.\n\n\n \n\n\n\n Freshwater Biology, 54(2): 331–344. 2009.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2427.2008.02118.x\n\n\n\n
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\n\n\n@article{vrede_effects_2009,\n\ttitle = {Effects of {N} : {P} loading ratios on phytoplankton community composition, primary production and {N} fixation in a eutrophic lake},\n\tvolume = {54},\n\tcopyright = {© 2008 The Authors, Journal compilation © 2008 Blackwell Publishing Ltd},\n\tissn = {1365-2427},\n\tshorttitle = {Effects of {N}},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2427.2008.02118.x},\n\tdoi = {10.1111/j.1365-2427.2008.02118.x},\n\tabstract = {1. The aim of this study was to assess the effects of different nitrogen (N) to phosphorus (P) loading ratios on phytoplankton community composition and primary production in a naturally eutrophic lake. Furthermore, the sources of N fuelling primary production were estimated using 15N stable isotope tracers. 2. A mesocosm experiment was performed with the same amount of P added to all mesocosms (similar to internal loading rates) but with a range of N additions (0–86 μm N), resulting in a gradient of N : P supply ratios. 3. Low N : P supply ratios resulted in a significant shift in the phytoplankton assemblage to a community dominated by N-fixing cyanobacteria and a supply of atmospheric N2 estimated to be up to 60\\% of total supply. 4. The N : P loading ratio had no significant effect on primary production, total nitrogen (TN) concentration or particulate N concentration. 5. Our results imply that a reduced N : P ratio of the nutrient load does not necessarily result in a lower TN concentration and downstream N export due to compensation by N-fixing cyanobacteria.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-08-31},\n\tjournal = {Freshwater Biology},\n\tauthor = {Vrede, Tobias and Ballantyne, Ashley and Mille‐Lindblom, Cecilia and Algesten, Grete and Gudasz, Cristian and Lindahl, Sandra and Brunberg, Anna Kristina},\n\tyear = {2009},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2427.2008.02118.x},\n\tkeywords = {\\#nosource, 15N stable isotopes, eutrophication, nitrogen, phosphorus, stoichiometry},\n\tpages = {331--344},\n}\n\n\n\n\n\n 1. The aim of this study was to assess the effects of different nitrogen (N) to phosphorus (P) loading ratios on phytoplankton community composition and primary production in a naturally eutrophic lake. Furthermore, the sources of N fuelling primary production were estimated using 15N stable isotope tracers. 2. A mesocosm experiment was performed with the same amount of P added to all mesocosms (similar to internal loading rates) but with a range of N additions (0–86 μm N), resulting in a gradient of N : P supply ratios. 3. Low N : P supply ratios resulted in a significant shift in the phytoplankton assemblage to a community dominated by N-fixing cyanobacteria and a supply of atmospheric N2 estimated to be up to 60% of total supply. 4. The N : P loading ratio had no significant effect on primary production, total nitrogen (TN) concentration or particulate N concentration. 5. Our results imply that a reduced N : P ratio of the nutrient load does not necessarily result in a lower TN concentration and downstream N export due to compensation by N-fixing cyanobacteria.\n
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\n \n \n\n \n \n \n \n \n \n Morphological and Behavioural Adaptations of Moose to Climate, Snow, and Forage.\n \n \n \n \n\n\n \n Lundmark, C.\n\n\n \n\n\n\n Ph.D. Thesis, Swedish University of Agricultural Sciences, Umeå, Sweden, 2008.\n \n\n\n\n
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\n\n\n@phdthesis{lundmark_morphological_2008,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Morphological and {Behavioural} {Adaptations} of {Moose} to {Climate}, {Snow}, and {Forage}},\n\turl = {https://publications.slu.se/?file=publ/show&id=19275},\n\tabstract = {This thesis focuses on the behavioural and morphological adaptations of moose to snow and climate: specifically, seasonal migration, habitat choice, and following behaviour, plus the relationships among morphology, climate, snow, and seasonality. I examine intake and availability of winter forage, and perform one of the first large-scale tests of a widely used optimal foraging model by videotaping free-ranging moose making their own choices. The study of seasonal migration and habitat choice showed that the effect of snow differs with variation in snow severity: in locations with large differences in snow depths in a short distance, snow depth is important, but in locations where snow depth is less variable, snow quality emerges as more important. The thesis is one of the first to use a new method to evaluate the importance of snow quality. Testing between competing hypotheses to explain morphology, the importance of snow was further emphasized relative to temperature and latitude. In snowier areas, moose had larger hooves and longer legs than expected from their size and age. Morphology both conformed to, and was in opposition to some of the most well-known ecogeographical rules: in areas with cold winters, moose were heavier (Bergmann’s rule) and had shorter ears (Allen’s rule). There was also some evidence that moose morphology was related to heat stress during summer. The quality of the two main winter forages (birch and willows) differed within and between species. Willows had more available browse, and lower levels of secondary defence compounds than birch, but also less nitrogen and more fibre. These differences in forage quality also emerged in the test of the Spalinger-Hobbs model, as moose preferentially fed on willow, which was also the faster food to ingest. Most importantly, the analysis revealed that the foraging parameters varied within a foraging bout, and thus parameterizing the model from only the first few minutes of a bout would greatly mis-estimate intake. In the face of climate change, my results emphasize the need for research relating behaviour and morphology to environmental conditions. As moose are well adapted to snow and winter conditions, climate change may have negative consequences on southern populations as temperatures will rise, and some ranges may become unsuitable.},\n\tlanguage = {en},\n\tschool = {Swedish University of Agricultural Sciences},\n\tauthor = {Lundmark, Caroline},\n\tcollaborator = {Ball, John P. and Danell, Kjell},\n\tyear = {2008},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n This thesis focuses on the behavioural and morphological adaptations of moose to snow and climate: specifically, seasonal migration, habitat choice, and following behaviour, plus the relationships among morphology, climate, snow, and seasonality. I examine intake and availability of winter forage, and perform one of the first large-scale tests of a widely used optimal foraging model by videotaping free-ranging moose making their own choices. The study of seasonal migration and habitat choice showed that the effect of snow differs with variation in snow severity: in locations with large differences in snow depths in a short distance, snow depth is important, but in locations where snow depth is less variable, snow quality emerges as more important. The thesis is one of the first to use a new method to evaluate the importance of snow quality. Testing between competing hypotheses to explain morphology, the importance of snow was further emphasized relative to temperature and latitude. In snowier areas, moose had larger hooves and longer legs than expected from their size and age. Morphology both conformed to, and was in opposition to some of the most well-known ecogeographical rules: in areas with cold winters, moose were heavier (Bergmann’s rule) and had shorter ears (Allen’s rule). There was also some evidence that moose morphology was related to heat stress during summer. The quality of the two main winter forages (birch and willows) differed within and between species. Willows had more available browse, and lower levels of secondary defence compounds than birch, but also less nitrogen and more fibre. These differences in forage quality also emerged in the test of the Spalinger-Hobbs model, as moose preferentially fed on willow, which was also the faster food to ingest. Most importantly, the analysis revealed that the foraging parameters varied within a foraging bout, and thus parameterizing the model from only the first few minutes of a bout would greatly mis-estimate intake. In the face of climate change, my results emphasize the need for research relating behaviour and morphology to environmental conditions. As moose are well adapted to snow and winter conditions, climate change may have negative consequences on southern populations as temperatures will rise, and some ranges may become unsuitable.\n
\n\n\n\n \n\n \n \n \n \n \n \n Links between Terrestrial Primary Production and Bacterial Production and Respiration in Lakes in a Climate Gradient in Subarctic Sweden.\n \n \n \n \n\n\n \n Jansson, M.; Hickler, T.; Jonsson, A.; and Karlsson, J.\n\n\n \n\n\n\n Ecosystems, 11(3): 367–376. April 2008.\n \n\n\n\n
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\n\n\n@article{jansson_links_2008,\n\ttitle = {Links between {Terrestrial} {Primary} {Production} and {Bacterial} {Production} and {Respiration} in {Lakes} in a {Climate} {Gradient} in {Subarctic} {Sweden}},\n\tvolume = {11},\n\tissn = {1432-9840, 1435-0629},\n\turl = {http://link.springer.com/article/10.1007/s10021-008-9127-2},\n\tdoi = {10.1007/s10021-008-9127-2},\n\tabstract = {We compared terrestrial net primary production (NPP) and terrestrial export of dissolved organic carbon (DOC) with lake water heterotrophic bacterial activity in 12 headwater lake catchments along an altitude gradient in subarctic Sweden. Modelled NPP declined strongly with altitude and annual air temperature decreases along the altitude gradient (6°C between the warmest and the coldest catchment). Estimated terrestrial DOC export to the lakes was closely correlated to NPP. Heterotrophic bacterial production (BP) and respiration (BR) were mainly based on terrestrial organic carbon and strongly correlated with the terrestrial DOC export. Excess respiration over PP of the pelagic system was similar to net emission of CO2 in the lakes. BR and CO2 emission made up considerably higher shares of the terrestrial DOC input in warm lakes than in cold lakes, implying that respiration and the degree of net heterotrophy in the lakes were dependant not only on terrestrial export of DOC, but also on characteristics in the lakes which changed along the gradient and affected the bacterial metabolization of allochthonous DOC. The study showed close links between terrestrial primary production, terrestrial DOC export and bacterial activity in lakes and how these relationships were dependant on air temperature. Increases in air temperature in high latitude unproductive systems might have considerable consequences for lake water productivity and release of CO2 to the atmosphere, which are ultimately determined by terrestrial primary production.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-06},\n\tjournal = {Ecosystems},\n\tauthor = {Jansson, Mats and Hickler, Thomas and Jonsson, Anders and Karlsson, Jan},\n\tmonth = apr,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Mineralization, bacterioplankton, lakes, subarctic, terrestrial DOC export, terrestrial primary production},\n\tpages = {367--376},\n}\n\n\n\n\n\n We compared terrestrial net primary production (NPP) and terrestrial export of dissolved organic carbon (DOC) with lake water heterotrophic bacterial activity in 12 headwater lake catchments along an altitude gradient in subarctic Sweden. Modelled NPP declined strongly with altitude and annual air temperature decreases along the altitude gradient (6°C between the warmest and the coldest catchment). Estimated terrestrial DOC export to the lakes was closely correlated to NPP. Heterotrophic bacterial production (BP) and respiration (BR) were mainly based on terrestrial organic carbon and strongly correlated with the terrestrial DOC export. Excess respiration over PP of the pelagic system was similar to net emission of CO2 in the lakes. BR and CO2 emission made up considerably higher shares of the terrestrial DOC input in warm lakes than in cold lakes, implying that respiration and the degree of net heterotrophy in the lakes were dependant not only on terrestrial export of DOC, but also on characteristics in the lakes which changed along the gradient and affected the bacterial metabolization of allochthonous DOC. The study showed close links between terrestrial primary production, terrestrial DOC export and bacterial activity in lakes and how these relationships were dependant on air temperature. Increases in air temperature in high latitude unproductive systems might have considerable consequences for lake water productivity and release of CO2 to the atmosphere, which are ultimately determined by terrestrial primary production.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant species traits are the predominant control on litter decomposition rates within biomes worldwide.\n \n \n \n \n\n\n \n Cornwell, W. K.; Cornelissen, J. H. C.; Amatangelo, K.; Dorrepaal, E.; Eviner, V. T.; Godoy, O.; Hobbie, S. E.; Hoorens, B.; Kurokawa, H.; Pérez‐Harguindeguy, N.; Quested, H. M.; Santiago, L. S.; Wardle, D. A.; Wright, I. J.; Aerts, R.; Allison, S. D.; Bodegom, P. V.; Brovkin, V.; Chatain, A.; Callaghan, T. V.; Díaz, S.; Garnier, E.; Gurvich, D. E.; Kazakou, E.; Klein, J. A.; Read, J.; Reich, P. B.; Soudzilovskaia, N. A.; Vaieretti, M. V.; and Westoby, M.\n\n\n \n\n\n\n Ecology Letters, 11(10): 1065–1071. October 2008.\n 01092\n\n\n\n
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\n\n\n@article{cornwell_plant_2008,\n\ttitle = {Plant species traits are the predominant control on litter decomposition rates within biomes worldwide},\n\tvolume = {11},\n\tcopyright = {© 2008 Blackwell Publishing Ltd/CNRS},\n\tissn = {1461-0248},\n\turl = {http://onlinelibrary.wiley.com/doi/abs/10.1111/j.1461-0248.2008.01219.x},\n\tdoi = {10.1111/j.1461-0248.2008.01219.x},\n\tabstract = {Worldwide decomposition rates depend both on climate and the legacy of plant functional traits as litter quality. To quantify the degree to which functional differentiation among species affects their litter decomposition rates, we brought together leaf trait and litter mass loss data for 818 species from 66 decomposition experiments on six continents. We show that: (i) the magnitude of species-driven differences is much larger than previously thought and greater than climate-driven variation; (ii) the decomposability of a species’ litter is consistently correlated with that species’ ecological strategy within different ecosystems globally, representing a new connection between whole plant carbon strategy and biogeochemical cycling. This connection between plant strategies and decomposability is crucial for both understanding vegetation–soil feedbacks, and for improving forecasts of the global carbon cycle.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2018-09-17},\n\tjournal = {Ecology Letters},\n\tauthor = {Cornwell, William K. and Cornelissen, Johannes H. C. and Amatangelo, Kathryn and Dorrepaal, Ellen and Eviner, Valerie T. and Godoy, Oscar and Hobbie, Sarah E. and Hoorens, Bart and Kurokawa, Hiroko and Pérez‐Harguindeguy, Natalia and Quested, Helen M. and Santiago, Louis S. and Wardle, David A. and Wright, Ian J. and Aerts, Rien and Allison, Steven D. and Bodegom, Peter Van and Brovkin, Victor and Chatain, Alex and Callaghan, Terry V. and Díaz, Sandra and Garnier, Eric and Gurvich, Diego E. and Kazakou, Elena and Klein, Julia A. and Read, Jenny and Reich, Peter B. and Soudzilovskaia, Nadejda A. and Vaieretti, M. Victoria and Westoby, Mark},\n\tmonth = oct,\n\tyear = {2008},\n\tnote = {01092},\n\tkeywords = {\\#nosource, Carbon cycling, decomposition, leaf economic spectrum, leaf traits, meta-analysis},\n\tpages = {1065--1071},\n}\n\n\n\n\n\n Worldwide decomposition rates depend both on climate and the legacy of plant functional traits as litter quality. To quantify the degree to which functional differentiation among species affects their litter decomposition rates, we brought together leaf trait and litter mass loss data for 818 species from 66 decomposition experiments on six continents. We show that: (i) the magnitude of species-driven differences is much larger than previously thought and greater than climate-driven variation; (ii) the decomposability of a species’ litter is consistently correlated with that species’ ecological strategy within different ecosystems globally, representing a new connection between whole plant carbon strategy and biogeochemical cycling. This connection between plant strategies and decomposability is crucial for both understanding vegetation–soil feedbacks, and for improving forecasts of the global carbon cycle.\n
\n\n\n\n \n\n \n \n \n \n \n \n Influence of environmental conditions, bacterial activity and viability on the viral component in 10 Antarctic lakes.\n \n \n \n \n\n\n \n Säwström, C.; Pearce, I.; Davidson, A. T.; Rosén, P.; and Laybourn-Parry, J.\n\n\n \n\n\n\n FEMS Microbiology Ecology, 63(1): 12–22. January 2008.\n 00035\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{sawstrom_influence_2008,\n\ttitle = {Influence of environmental conditions, bacterial activity and viability on the viral component in 10 {Antarctic} lakes},\n\tvolume = {63},\n\tissn = {0168-6496},\n\turl = {https://academic.oup.com/femsec/article/63/1/12/490189},\n\tdoi = {10.1111/j.1574-6941.2007.00407.x},\n\tabstract = {Abstract. The influence of biotic and environmental variables on the abundance of virus-like particles (VLP) and lysogeny was investigated by examining 10 Anta},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-06-13},\n\tjournal = {FEMS Microbiology Ecology},\n\tauthor = {Säwström, Christin and Pearce, Imojen and Davidson, Andrew T. and Rosén, Peter and Laybourn-Parry, Johanna},\n\tmonth = jan,\n\tyear = {2008},\n\tnote = {00035},\n\tkeywords = {\\#nosource},\n\tpages = {12--22},\n}\n\n\n\n\n\n Abstract. The influence of biotic and environmental variables on the abundance of virus-like particles (VLP) and lysogeny was investigated by examining 10 Anta\n
\n\n\n\n \n\n \n \n \n \n \n \n Fourier transform infrared spectroscopy, a new cost-effective tool for quantitative analysis of biogeochemical properties in long sediment records.\n \n \n \n \n\n\n \n Vogel, H.; Rosén, P.; Wagner, B.; Melles, M.; and Persson, P.\n\n\n \n\n\n\n Journal of Paleolimnology, 40(2): 689–702. August 2008.\n 00070\n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{vogel_fourier_2008,\n\ttitle = {Fourier transform infrared spectroscopy, a new cost-effective tool for quantitative analysis of biogeochemical properties in long sediment records},\n\tvolume = {40},\n\tissn = {0921-2728, 1573-0417},\n\turl = {https://link.springer.com/article/10.1007/s10933-008-9193-7},\n\tdoi = {10.1007/s10933-008-9193-7},\n\tabstract = {Measurements of Fourier transform infrared spectroscopy (FTIRS) in the mid-infrared (MIR) region were conducted on sedimentary records from Lake El’gygytgyn, NE Siberia, and Lake Ohrid, Albania/Macedonia. Calibration models relating FTIR spectral information to biogeochemical property concentrations were established using partial least squares regression (PLSR). They showed good statistical performance for total organic carbon (TOC), total nitrogen (TN), and biogenic silica (opal) in the sediment record from Lake El’gygytgyn, and for TOC, total inorganic carbon (TIC), TN, and opal in sediments from Lake Ohrid. In both cases, the calibration models were successfully applied for down-core analysis. The results, in combination with the small amount of sample material needed, negligible sample pre-treatments, and low costs of analysis, demonstrate that FTIRS is a promising, cost-effective tool that allows high-resolution paleolimnological studies.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2018-06-14},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Vogel, Hendrik and Rosén, Peter and Wagner, Bernd and Melles, Martin and Persson, Per},\n\tmonth = aug,\n\tyear = {2008},\n\tnote = {00070},\n\tkeywords = {\\#nosource},\n\tpages = {689--702},\n}\n\n\n\n\n\n Measurements of Fourier transform infrared spectroscopy (FTIRS) in the mid-infrared (MIR) region were conducted on sedimentary records from Lake El’gygytgyn, NE Siberia, and Lake Ohrid, Albania/Macedonia. Calibration models relating FTIR spectral information to biogeochemical property concentrations were established using partial least squares regression (PLSR). They showed good statistical performance for total organic carbon (TOC), total nitrogen (TN), and biogenic silica (opal) in the sediment record from Lake El’gygytgyn, and for TOC, total inorganic carbon (TIC), TN, and opal in sediments from Lake Ohrid. In both cases, the calibration models were successfully applied for down-core analysis. The results, in combination with the small amount of sample material needed, negligible sample pre-treatments, and low costs of analysis, demonstrate that FTIRS is a promising, cost-effective tool that allows high-resolution paleolimnological studies.\n
\n\n\n\n \n\n \n \n \n \n \n \n Living in Snowy Environments: Quantifying The Influence of Snow on Moose Behavior.\n \n \n \n \n\n\n \n Lundmark, C.; and Ball, J. P.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 40(1): 111–118. February 2008.\n 00032\n\n\n\n
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\n\n\n@article{lundmark_living_2008,\n\ttitle = {Living in {Snowy} {Environments}: {Quantifying} {The} {Influence} of {Snow} on {Moose} {Behavior}},\n\tvolume = {40},\n\tissn = {1523-0430},\n\tshorttitle = {Living in {Snowy} {Environments}},\n\turl = {http://www.bioone.org/doi/abs/10.1657/1523-0430(06-103)[LUNDMARK]2.0.CO;2},\n\tdoi = {10.1657/1523-0430(06-103)[LUNDMARK]2.0.CO;2},\n\tabstract = {We investigated the effects of snow and environmental variables on the depths to which moose sank in snow, and the extent to which moose followed in the tracks of other free-ranging moose in the mountains of the subarctic areas of northernmost Sweden. We tested a method to combine the variables that affect snow quality (e.g. density and hardness) into a single variable that is easier to measure in the field. We also studied the snow conditions in the summer and winter ranges of migrating moose. First, we performed correlation analyses that revealed that sinking depths of moose decreased with increasing snow quality, snow depth, altitude, and air temperature. Next, we next used the Akaike information criterion (AIC) to determine the best model of sinking depth, which indicated that the important variables were snow quality, altitude, and snow temperature. For trail-following behavior, the best model included air temperature only. Regarding seasonal ranges, winter ranges had considerably less snow than the summer ranges that these individual moose left, but snow quality did not differ. Overall, our new method to index snow quality (here, using a dynamometer to measure the force required to press a simulated moose foot down in the snow to the depth of a moose footprint) shows promise, and we suggest that future studies of ungulate winter ecology investigate it further.},\n\tnumber = {1},\n\turldate = {2018-06-13},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Lundmark, Caroline and Ball, John P.},\n\tmonth = feb,\n\tyear = {2008},\n\tnote = {00032},\n\tkeywords = {\\#nosource},\n\tpages = {111--118},\n}\n\n\n\n\n\n We investigated the effects of snow and environmental variables on the depths to which moose sank in snow, and the extent to which moose followed in the tracks of other free-ranging moose in the mountains of the subarctic areas of northernmost Sweden. We tested a method to combine the variables that affect snow quality (e.g. density and hardness) into a single variable that is easier to measure in the field. We also studied the snow conditions in the summer and winter ranges of migrating moose. First, we performed correlation analyses that revealed that sinking depths of moose decreased with increasing snow quality, snow depth, altitude, and air temperature. Next, we next used the Akaike information criterion (AIC) to determine the best model of sinking depth, which indicated that the important variables were snow quality, altitude, and snow temperature. For trail-following behavior, the best model included air temperature only. Regarding seasonal ranges, winter ranges had considerably less snow than the summer ranges that these individual moose left, but snow quality did not differ. Overall, our new method to index snow quality (here, using a dynamometer to measure the force required to press a simulated moose foot down in the snow to the depth of a moose footprint) shows promise, and we suggest that future studies of ungulate winter ecology investigate it further.\n
\n\n\n\n \n\n \n \n \n \n \n \n Torneträsk tree-ring width and density ad 500–2004: a test of climatic sensitivity and a new 1500-year reconstruction of north Fennoscandian summers.\n \n \n \n \n\n\n \n Grudd, H.\n\n\n \n\n\n\n Climate Dynamics, 31(7-8): 843–857. December 2008.\n 00195\n\n\n\n
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\n\n\n@article{grudd_tornetrask_2008,\n\ttitle = {Torneträsk tree-ring width and density ad 500–2004: a test of climatic sensitivity and a new 1500-year reconstruction of north {Fennoscandian} summers},\n\tvolume = {31},\n\tissn = {0930-7575, 1432-0894},\n\tshorttitle = {Torneträsk tree-ring width and density ad 500–2004},\n\turl = {http://link.springer.com/10.1007/s00382-007-0358-2},\n\tdoi = {10.1007/s00382-007-0358-2},\n\tabstract = {00187},\n\tlanguage = {en},\n\tnumber = {7-8},\n\turldate = {2016-09-02},\n\tjournal = {Climate Dynamics},\n\tauthor = {Grudd, Håkan},\n\tmonth = dec,\n\tyear = {2008},\n\tnote = {00195},\n\tkeywords = {\\#nosource},\n\tpages = {843--857},\n}\n\n\n\n\n\n 00187\n
\n\n\n\n \n\n \n \n \n \n \n Phytoplankton responses to nitrogen and phosphorus enrichment in unproductive Swedish lakes along a gradient of atmospheric nitrogen deposition.\n \n \n \n\n\n \n Bergstroem, A.; Jonsson, A.; and Jansson, M.\n\n\n \n\n\n\n Aquatic Biology, 4(1): 55–64. 2008.\n 00000\n\n\n\n
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\n\n\n@article{bergstroem_phytoplankton_2008,\n\ttitle = {Phytoplankton responses to nitrogen and phosphorus enrichment in unproductive {Swedish} lakes along a gradient of atmospheric nitrogen deposition},\n\tvolume = {4},\n\tissn = {1864-7790},\n\tdoi = {10.3354/ab00099},\n\tabstract = {Lake sampling and in situ nutrient enrichment enclosure experiments with nitrogen (N) and phosphorus (P) were conducted in unproductive Swedish lakes along a gradient of increasing atmospheric N-deposition. The regional and seasonal patterns of nutrient limitation of phytoplankton were clearly related to the amounts of N-deposition and N-inputs the lakes received. In areas of low N-deposition in northern Sweden, N-limitation of phytoplankton was evident throughout the summer season due to high catchment N-retention and very low dissolved inorganic N (DIN) inputs during the early summer. High N-deposition in the south was accompanied by high lake DIN-concentrations during the early summer and subsequent P-limitation of phytoplankton. However, P-limitation did not persist over the summer and, as a consequence of a declining DIN-pool, the lakes switched to dual- and co-limitation by N and P, and then to N-limitation. Generally, the lakes were N-limited rather than P-limited during the summer. We conclude that N-limitation is probably a natural state of the unproductive lakes studied, but P-limitation of variable intensity and duration has been induced by elevated atmospheric N-deposition.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Aquatic Biology},\n\tauthor = {Bergstroem, Ann-Kristin and Jonsson, Anders and Jansson, Mats},\n\tyear = {2008},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Ecosystems, N-deposition, N-limitation, P-limitation, Seasonal variation, bacterioplankton, climate, colorado front range, eutrophication, growth, lakes, marine, nutrient limitation, nutrients, organic-carbon, ortrasket, phytoplankton},\n\tpages = {55--64},\n}\n\n\n\n\n\n Lake sampling and in situ nutrient enrichment enclosure experiments with nitrogen (N) and phosphorus (P) were conducted in unproductive Swedish lakes along a gradient of increasing atmospheric N-deposition. The regional and seasonal patterns of nutrient limitation of phytoplankton were clearly related to the amounts of N-deposition and N-inputs the lakes received. In areas of low N-deposition in northern Sweden, N-limitation of phytoplankton was evident throughout the summer season due to high catchment N-retention and very low dissolved inorganic N (DIN) inputs during the early summer. High N-deposition in the south was accompanied by high lake DIN-concentrations during the early summer and subsequent P-limitation of phytoplankton. However, P-limitation did not persist over the summer and, as a consequence of a declining DIN-pool, the lakes switched to dual- and co-limitation by N and P, and then to N-limitation. Generally, the lakes were N-limited rather than P-limited during the summer. We conclude that N-limitation is probably a natural state of the unproductive lakes studied, but P-limitation of variable intensity and duration has been induced by elevated atmospheric N-deposition.\n
\n\n\n\n \n\n \n \n \n \n \n Amino acid uptake among wide-ranging moss species may contribute to their strong position in higher-latitude ecosystems.\n \n \n \n\n\n \n Krab, E. J.; Cornelissen, J. H. C.; Lang, S. I.; and van Logtestijn, R. S. P.\n\n\n \n\n\n\n Plant and Soil, 304(1-2): 199–208. March 2008.\n 00028\n\n\n\n
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\n\n\n@article{krab_amino_2008,\n\ttitle = {Amino acid uptake among wide-ranging moss species may contribute to their strong position in higher-latitude ecosystems},\n\tvolume = {304},\n\tissn = {0032-079X},\n\tdoi = {10.1007/s11104-008-9540-5},\n\tabstract = {Plants that can take up amino acids directly from the soil solution may have a competitive advantage in ecosystems where inorganic nitrogen sources are scarce. We hypothesized that diverse mosses in cold, N-stressed ecosystems share this ability. We experimentally tested 11 sub-arctic Swedish moss species of wide-ranging taxa and growth form for their ability to take up double labelled (N-15 and C-13) glycine and aspartic acid in a laboratory setup as well as in a realistic field setting. All species were able to take up amino acids injected into the soil solution to some extent, although field uptake was marginal to absent for the endohydric Polytrichum commune. The 11 moss species on average took up 36 +/- 5\\% of the injected glycine and 18 +/- 2\\% of the aspartic acid in the lab experiment. Field uptake of both glycine (24 +/- 5\\%) and aspartic acid (10 +/- 2\\%) was lower than in the lab. Overall differences in uptake amongst species appeared to be positively associated with habitat wetness and/or turf density among different Sphagnum species and among non-Sphagnum species, respectively. Species from habitats of lower inorganic N availability, as indicated tentatively by lower tissue N concentrations, showed relatively strong amino acid uptake, but this was only significant for the field uptake among non-Sphagnum mosses. Further experiments are needed to test for consistent differences in amino acid uptake capacity among species and functional groups as determined by their functional traits, and to test how the affinity of cold-biome mosses for amino acids compares to that for ammonium or nitrate. Still, our results support the view that widespread moss species in cold, N-stressed ecosystems may derive a significant proportion of their nitrogen demand from free amino acids. This might give them a competitive advantage over plants that depend strongly on inorganic N sources.},\n\tlanguage = {English},\n\tnumber = {1-2},\n\tjournal = {Plant and Soil},\n\tauthor = {Krab, Eveline J. and Cornelissen, Johannes H. C. and Lang, Simone I. and van Logtestijn, Richard S. P.},\n\tmonth = mar,\n\tyear = {2008},\n\tnote = {00028},\n\tkeywords = {\\#nosource, Bryophyte, Bryophytes, Plants, abundance, arctic tundra soils, aspartic acid, ecology, glycine, isotope labeling, nitrogen availability, organic nitrogen, photosynthesis, responses, sub-Arctic, traits, vegetation},\n\tpages = {199--208},\n}\n\n\n\n\n\n Plants that can take up amino acids directly from the soil solution may have a competitive advantage in ecosystems where inorganic nitrogen sources are scarce. We hypothesized that diverse mosses in cold, N-stressed ecosystems share this ability. We experimentally tested 11 sub-arctic Swedish moss species of wide-ranging taxa and growth form for their ability to take up double labelled (N-15 and C-13) glycine and aspartic acid in a laboratory setup as well as in a realistic field setting. All species were able to take up amino acids injected into the soil solution to some extent, although field uptake was marginal to absent for the endohydric Polytrichum commune. The 11 moss species on average took up 36 +/- 5% of the injected glycine and 18 +/- 2% of the aspartic acid in the lab experiment. Field uptake of both glycine (24 +/- 5%) and aspartic acid (10 +/- 2%) was lower than in the lab. Overall differences in uptake amongst species appeared to be positively associated with habitat wetness and/or turf density among different Sphagnum species and among non-Sphagnum species, respectively. Species from habitats of lower inorganic N availability, as indicated tentatively by lower tissue N concentrations, showed relatively strong amino acid uptake, but this was only significant for the field uptake among non-Sphagnum mosses. Further experiments are needed to test for consistent differences in amino acid uptake capacity among species and functional groups as determined by their functional traits, and to test how the affinity of cold-biome mosses for amino acids compares to that for ammonium or nitrate. Still, our results support the view that widespread moss species in cold, N-stressed ecosystems may derive a significant proportion of their nitrogen demand from free amino acids. This might give them a competitive advantage over plants that depend strongly on inorganic N sources.\n
\n\n\n\n \n\n \n \n \n \n \n Winter respiration of allochthonous and autochthonous organic carbon in a subarctic clear-water lake.\n \n \n \n\n\n \n Karlsson, J.; Ask, J.; and Jansson, M.\n\n\n \n\n\n\n Limnology and Oceanography, 53(3): 948–954. May 2008.\n \n\n\n\n
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\n\n\n@article{karlsson_winter_2008,\n\ttitle = {Winter respiration of allochthonous and autochthonous organic carbon in a subarctic clear-water lake},\n\tvolume = {53},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2008.53.3.0948},\n\tabstract = {We studied a small subarctic lake to assess the magnitude of winter respiration and the organic carbon ( OC) source for this respiration. The concentration and stable isotopic composition ( delta C-13) of dissolved inorganic carbon ( DIC) accumulating in the lake water under ice was analyzed over one winter (7 months). The DIC concentration increased and the delta C-13 of DIC decreased over time, with the greatest changes at the lake bottom. Winter respiration was 26\\% of annual respiration in the lake. Keeling plot analysis demonstrated that the delta C-13 of respired DIC varied spatially, high delta C-13 values occurring at shallow ( 2.5 m, -21.7\\%) compared with intermediate ( 4 m, -25.1\\%) and deep ( 6 m, -27.8\\%) locations in the lake. The variation in the delta C-13 of respired DIC was related to the variation in the delta C-13 of the sediments between locations, suggesting that sediment OC supported much of the winter respiration and that the dominant OC source for respiration was OC from benthic algae at shallow locations and settled OC, of predominately terrestrial origin, at deep locations. The respiration of OC from benthic algae constituted 55\\% of the winter respiration, equaling 54\\% of the primary production by benthic algae the previous summer. The study indicates the importance of temporal and spatial variation in respiration for the metabolism and net DIC production in unproductive high-latitude lakes; both allochthonous and autochthonous carbon can contribute to winter DIC accumulation and, consequently, to spring CO2 emissions from lakes.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Karlsson, Jan and Ask, Jenny and Jansson, Mats},\n\tmonth = may,\n\tyear = {2008},\n\tkeywords = {\\#nosource, CO2, biomass, boreal lakes, dioxide supersaturation, humic lakes, metabolism, northern sweden, sediment respiration, temperate},\n\tpages = {948--954},\n}\n\n\n\n\n\n We studied a small subarctic lake to assess the magnitude of winter respiration and the organic carbon ( OC) source for this respiration. The concentration and stable isotopic composition ( delta C-13) of dissolved inorganic carbon ( DIC) accumulating in the lake water under ice was analyzed over one winter (7 months). The DIC concentration increased and the delta C-13 of DIC decreased over time, with the greatest changes at the lake bottom. Winter respiration was 26% of annual respiration in the lake. Keeling plot analysis demonstrated that the delta C-13 of respired DIC varied spatially, high delta C-13 values occurring at shallow ( 2.5 m, -21.7%) compared with intermediate ( 4 m, -25.1%) and deep ( 6 m, -27.8%) locations in the lake. The variation in the delta C-13 of respired DIC was related to the variation in the delta C-13 of the sediments between locations, suggesting that sediment OC supported much of the winter respiration and that the dominant OC source for respiration was OC from benthic algae at shallow locations and settled OC, of predominately terrestrial origin, at deep locations. The respiration of OC from benthic algae constituted 55% of the winter respiration, equaling 54% of the primary production by benthic algae the previous summer. The study indicates the importance of temporal and spatial variation in respiration for the metabolism and net DIC production in unproductive high-latitude lakes; both allochthonous and autochthonous carbon can contribute to winter DIC accumulation and, consequently, to spring CO2 emissions from lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Global Change and the High-Latitude Environment: High Latitude Terrestrial and Freshwater Ecosystems: Interactions and Response to Environmental Change; Abisko, Sweden, 11–14 September 2007.\n \n \n \n \n\n\n \n Karlsson, J.; and Giesler, R.\n\n\n \n\n\n\n Eos, Transactions American Geophysical Union, 89(10): 97–97. March 2008.\n \n\n\n\n
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\n\n\n@article{karlsson_global_2008,\n\ttitle = {Global {Change} and the {High}-{Latitude} {Environment}: {High} {Latitude} {Terrestrial} and {Freshwater} {Ecosystems}: {Interactions} and {Response} to {Environmental} {Change}; {Abisko}, {Sweden}, 11–14 {September} 2007},\n\tvolume = {89},\n\tissn = {2324-9250},\n\tshorttitle = {Global {Change} and the {High}-{Latitude} {Environment}},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2008EO100007/abstract},\n\tdoi = {10.1029/2008EO100007},\n\tabstract = {Terrestrial and aquatic scientists took part in a workshop in Sweden to discuss cross-system linkages that strongly influence the structure and function of terrestrial and aquatic ecosystems, which effects may be altered by future environmental change. Sixty-five researchers, mainly from northern Europe and North America, attended the meeting. Through a series of presentations and discussions several clear themes emerged. For example, workshop participants discussed how high-latitude freshwater ecosystems are strongly influenced by nutrient and material inputs from the surrounding terrestrial environment. In particular, the magnitude and quality of carbon, nitrogen, and phosphorus exported from terrestrial ecosystems are recognized as major drivers of the productivity and biological structure of aquatic ecosystems.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2017-02-06},\n\tjournal = {Eos, Transactions American Geophysical Union},\n\tauthor = {Karlsson, Jan and Giesler, Reiner},\n\tmonth = mar,\n\tyear = {2008},\n\tkeywords = {\\#nosource, 0428 Carbon cycling, 1630 Impacts of global change, Impacts of global change, carbon cycling},\n\tpages = {97--97},\n}\n\n\n\n\n\n Terrestrial and aquatic scientists took part in a workshop in Sweden to discuss cross-system linkages that strongly influence the structure and function of terrestrial and aquatic ecosystems, which effects may be altered by future environmental change. Sixty-five researchers, mainly from northern Europe and North America, attended the meeting. Through a series of presentations and discussions several clear themes emerged. For example, workshop participants discussed how high-latitude freshwater ecosystems are strongly influenced by nutrient and material inputs from the surrounding terrestrial environment. In particular, the magnitude and quality of carbon, nitrogen, and phosphorus exported from terrestrial ecosystems are recognized as major drivers of the productivity and biological structure of aquatic ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Experimental dietary manipulations for determining the relative importance of allochthonous and autochthonous food resources in tropical streams.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n Freshwater Biology, 53(1): 139–147. January 2008.\n \n\n\n\n
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\n\n\n@article{lau_experimental_2008,\n\ttitle = {Experimental dietary manipulations for determining the relative importance of allochthonous and autochthonous food resources in tropical streams},\n\tvolume = {53},\n\tissn = {1365-2427},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1111/j.1365-2427.2007.01873.x/abstract},\n\tdoi = {10.1111/j.1365-2427.2007.01873.x},\n\tabstract = {1. Autochthonous sources of organic matter appear to make a minor contribution to food webs in temperate forest streams, but their roles in supporting consumer biomass in tropical lotic environments have received little attention. We investigated the importance of autochthonous and allochthonous food sources to Brotia hainanensis (Pachychilidae), a detritivorous and algivorous snail common in Hong Kong hillstreams, using experimental dietary manipulations and assimilation-based analyses, including stoichiometry, carbon (C) and nitrogen (N) stable isotopes and fatty acid (FA) profiles. 2. Juvenile B. hainanensis collected in Pak Ngau Shek Stream were cultured under controlled laboratory conditions and fed for 2 months with either conditioned Liquidambar formosana (Hamamelidaceae) leaf litter or periphyton. Samples of B. hainanensis were also collected from the stream at the end of the experiment for comparison with snails reared in the laboratory. 3. Periphyton and leaf litter exhibited marked differences in C/N ratios, δ13C and δ15N values and FA profiles. Stable isotope analysis and FA profiling of laboratory-reared and field-collected B. hainanensis both confirmed that snails relied primarily on autochthonous foods, especially periphytic diatoms and cyanobacteria. Stoichiometry results indicated that periphyton was a more nutritious food (with lower C/N ratio) than leaf litter. 4. This is the first study demonstrating that the combined use of stable isotopes and FA profiles is an effective diagnostic tool to trace the basal food sources of consumers in natural stream habitats. Our findings further support the hypothesis that primary production in tropical streams is generally more important to aquatic consumers than inputs of terrestrial detritus.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-05-27},\n\tjournal = {Freshwater Biology},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y. and Dudgeon, David},\n\tmonth = jan,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Autochthonous, Fatty acids, allochthonous, stable isotopes, stoichiometry},\n\tpages = {139--147},\n}\n\n\n\n\n\n 1. Autochthonous sources of organic matter appear to make a minor contribution to food webs in temperate forest streams, but their roles in supporting consumer biomass in tropical lotic environments have received little attention. We investigated the importance of autochthonous and allochthonous food sources to Brotia hainanensis (Pachychilidae), a detritivorous and algivorous snail common in Hong Kong hillstreams, using experimental dietary manipulations and assimilation-based analyses, including stoichiometry, carbon (C) and nitrogen (N) stable isotopes and fatty acid (FA) profiles. 2. Juvenile B. hainanensis collected in Pak Ngau Shek Stream were cultured under controlled laboratory conditions and fed for 2 months with either conditioned Liquidambar formosana (Hamamelidaceae) leaf litter or periphyton. Samples of B. hainanensis were also collected from the stream at the end of the experiment for comparison with snails reared in the laboratory. 3. Periphyton and leaf litter exhibited marked differences in C/N ratios, δ13C and δ15N values and FA profiles. Stable isotope analysis and FA profiling of laboratory-reared and field-collected B. hainanensis both confirmed that snails relied primarily on autochthonous foods, especially periphytic diatoms and cyanobacteria. Stoichiometry results indicated that periphyton was a more nutritious food (with lower C/N ratio) than leaf litter. 4. This is the first study demonstrating that the combined use of stable isotopes and FA profiles is an effective diagnostic tool to trace the basal food sources of consumers in natural stream habitats. Our findings further support the hypothesis that primary production in tropical streams is generally more important to aquatic consumers than inputs of terrestrial detritus.\n
\n\n\n\n \n\n \n \n \n \n \n \n Experimental dietary manipulations and concurrent use of assimilation-based analyses for elucidation of consumer–resource relationships in tropical streams.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n Marine and Freshwater Research, 59(11): 963–970. December 2008.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{lau_experimental_2008,\n\ttitle = {Experimental dietary manipulations and concurrent use of assimilation-based analyses for elucidation of consumer–resource relationships in tropical streams},\n\tvolume = {59},\n\tissn = {1448-6059},\n\turl = {http://www.publish.csiro.au/MF/MF07213},\n\tdoi = {10.1071/MF07213},\n\tabstract = {The relative contribution of autochthonous foods to consumer biomass in small tropical streams is unknown, but extrapolation of findings from temperate forest streams, where food webs are based on allochthonous resources, might be misleading. Experimental dietary manipulations were conducted to investigate the food used by the snail Brotia hainanensis (Pachychilidae), a generalist primary consumer common in Hong Kong streams, through the concurrent use of stoichiometry, stable isotope analysis (SIA) and fatty acid (FA) profiling. Juvenile B. hainanensis collected from the field were cultured under laboratory conditions and fed with conditioned leaf litter, periphyton or commercial fish-food flakes for 6 months and then compared with field-collected snails at the end of the trial. The results of the SIA and FA profiling showed that snails depended primarily on algal food. Prolonged feeding with leaf litter put B. hainanensis under elemental constraints and litter-fed snails deviated from strict stoichiometric homeostasis. Periphyton-fed, flake-fed and field-collected snails contained more total lipids and autochthonous FA biomarkers than litter-fed snails. The concurrent application of assimilation-based analyses allowed effective and accurate elucidation of consumer–resource relationships and, in the present study, confirmed the importance of autochthonous energy in a tropical stream food web. This approach will be useful for investigating complex trophic interactions.},\n\tlanguage = {en},\n\tnumber = {11},\n\turldate = {2017-05-27},\n\tjournal = {Marine and Freshwater Research},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y. and Dudgeon, David},\n\tmonth = dec,\n\tyear = {2008},\n\tkeywords = {\\#nosource},\n\tpages = {963--970},\n}\n\n\n\n\n\n The relative contribution of autochthonous foods to consumer biomass in small tropical streams is unknown, but extrapolation of findings from temperate forest streams, where food webs are based on allochthonous resources, might be misleading. Experimental dietary manipulations were conducted to investigate the food used by the snail Brotia hainanensis (Pachychilidae), a generalist primary consumer common in Hong Kong streams, through the concurrent use of stoichiometry, stable isotope analysis (SIA) and fatty acid (FA) profiling. Juvenile B. hainanensis collected from the field were cultured under laboratory conditions and fed with conditioned leaf litter, periphyton or commercial fish-food flakes for 6 months and then compared with field-collected snails at the end of the trial. The results of the SIA and FA profiling showed that snails depended primarily on algal food. Prolonged feeding with leaf litter put B. hainanensis under elemental constraints and litter-fed snails deviated from strict stoichiometric homeostasis. Periphyton-fed, flake-fed and field-collected snails contained more total lipids and autochthonous FA biomarkers than litter-fed snails. The concurrent application of assimilation-based analyses allowed effective and accurate elucidation of consumer–resource relationships and, in the present study, confirmed the importance of autochthonous energy in a tropical stream food web. This approach will be useful for investigating complex trophic interactions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Role of Surface Vegetation in 210Pb-Dating of Peat Cores.\n \n \n \n \n\n\n \n Olid, C.; Garcia-Orellana, J.; Martínez-Cortizas, A.; Masqué, P.; Peiteado, E.; and Sanchez-Cabeza, J.\n\n\n \n\n\n\n Environmental Science & Technology, 42(23): 8858–8864. December 2008.\n 00034\n\n\n\n
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\n\n\n@article{olid_role_2008,\n\ttitle = {Role of {Surface} {Vegetation} in {210Pb}-{Dating} of {Peat} {Cores}},\n\tvolume = {42},\n\tissn = {0013-936X},\n\turl = {http://dx.doi.org/10.1021/es801552v},\n\tdoi = {10.1021/es801552v},\n\tabstract = {210Pb-dated ombrotrophic peat cores have been widely used to reconstruct the atmospheric fluxes of heavy metals for the past century. Many of these studies rarely include the overlying vegetation compartment (i.e., the aerial part of vegetation and decayed plant remains) in the analysis although it represents the first layer capturing atmospheric deposition. The aim of this study was to evaluate the radionuclide and Pb content of this biologically active layer in bogs and to assess its implications on the total inventories and the 210Pb-derived chronology. We analyzed two short ombrotrophic peat cores from the same bog (Chao de Lamoso, Galicia, Spain) for 210Pb, artificial radionuclides (137Cs and 241Am), and Pb. The total Pb inventory was underestimated by about 12\\% when the plant material was not included in the record. The atmospheric origin of 210Pb and the uptake of 137Cs by roots led to significant activities of these radionuclides in the upper layers. Therefore, removing them from the peat record would imply even larger underestimations of the total inventories, ranging from 25\\% to 36\\% for 137Cs and from 39\\% to 49\\% for 210Pb. In contrast to the chronologies inferred from the constant rate of supply (CRS) model when only peat layers are considered, the 210Pb chronology agreed well with artificial radionuclide dating when surface vegetation was included. These results suggest that an accurate peat chronology requires an initial evaluation of the relevance of plant inventories and emphasizes the need of considering the biologically active layer when atmospheric fluxes of heavy metals and other pollutants are reconstructed.},\n\tnumber = {23},\n\turldate = {2017-04-28},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Olid, Carolina and Garcia-Orellana, Jordi and Martínez-Cortizas, Antonio and Masqué, Pere and Peiteado, Eva and Sanchez-Cabeza, Joan-Albert},\n\tmonth = dec,\n\tyear = {2008},\n\tnote = {00034},\n\tkeywords = {\\#nosource},\n\tpages = {8858--8864},\n}\n\n\n\n\n\n 210Pb-dated ombrotrophic peat cores have been widely used to reconstruct the atmospheric fluxes of heavy metals for the past century. Many of these studies rarely include the overlying vegetation compartment (i.e., the aerial part of vegetation and decayed plant remains) in the analysis although it represents the first layer capturing atmospheric deposition. The aim of this study was to evaluate the radionuclide and Pb content of this biologically active layer in bogs and to assess its implications on the total inventories and the 210Pb-derived chronology. We analyzed two short ombrotrophic peat cores from the same bog (Chao de Lamoso, Galicia, Spain) for 210Pb, artificial radionuclides (137Cs and 241Am), and Pb. The total Pb inventory was underestimated by about 12% when the plant material was not included in the record. The atmospheric origin of 210Pb and the uptake of 137Cs by roots led to significant activities of these radionuclides in the upper layers. Therefore, removing them from the peat record would imply even larger underestimations of the total inventories, ranging from 25% to 36% for 137Cs and from 39% to 49% for 210Pb. In contrast to the chronologies inferred from the constant rate of supply (CRS) model when only peat layers are considered, the 210Pb chronology agreed well with artificial radionuclide dating when surface vegetation was included. These results suggest that an accurate peat chronology requires an initial evaluation of the relevance of plant inventories and emphasizes the need of considering the biologically active layer when atmospheric fluxes of heavy metals and other pollutants are reconstructed.\n
\n\n\n\n \n\n \n \n \n \n \n \n Seasonal temperatures for the past ∼400 years reconstructed from diatom and chironomid assemblages in a high-altitude lake (Lej da la Tscheppa, Switzerland).\n \n \n \n \n\n\n \n Gunten, L. v.; Heiri, O.; Bigler, C.; Leeuwen, J. v.; Casty, C.; Lotter, A. F.; and Sturm, M.\n\n\n \n\n\n\n Journal of Paleolimnology, 39(3): 283–299. April 2008.\n \n\n\n\n
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\n\n\n@article{gunten_seasonal_2008,\n\ttitle = {Seasonal temperatures for the past ∼400 years reconstructed from diatom and chironomid assemblages in a high-altitude lake ({Lej} da la {Tscheppa}, {Switzerland})},\n\tvolume = {39},\n\tissn = {0921-2728, 1573-0417},\n\turl = {http://link.springer.com/article/10.1007/s10933-007-9103-4},\n\tdoi = {10.1007/s10933-007-9103-4},\n\tabstract = {We analysed a 42 cm long sediment record from Lej da la Tscheppa, a high-altitude lake (2,616 m a.s.l.) in the Upper Engadine valley (Switzerland) for subfossil diatoms, chironomids and pollen. The chronology of the top 21 cm of the record was established using 210Pb analysis using a constant-rate-of-supply model, and validated with 137Cs measurements and the content of spheroidal carbonaceous particles. A tentative chronology for the lower part of the core was obtained through extrapolation of the sedimentation rates in the uppermost part of the record. Pollen assemblages in the record reflect regional changes in forestation and land-use patterns in the Upper Engadine valley and show no evidence of significant local human activity in the lake’s catchment. Diatom assemblages record a distinct increase in planktonic taxa since the early 19th century, suggesting a decrease in the duration of ice-cover. In contrast, chironomid assemblages remained stable during a large part of the record. We applied an established chironomid-based July air temperature transfer function and a newly developed diatom-based spring air temperature transfer function to reconstruct past seasonal air temperature changes at Lej da la Tscheppa. The reconstructions indicate a diatom-inferred warming trend in spring temperatures during the past ca. 400 years, whereas chironomid-inferred summer temperatures suggest a slight cooling trend. These biota-based reconstructions are in good agreement with the centennial-scale temperature trend in an independent reconstruction of regional temperatures in the Upper Engadine region based on instrumental records and documentary proxy evidence from the Alps. Our results suggest that, in high-altitude lakes, independent chironomid- and diatom-based seasonal temperature reconstruction is possible and can be successfully used to track seasonal temperature trends.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Gunten, Lucien von and Heiri, Oliver and Bigler, Christian and Leeuwen, Jacqueline van and Casty, Carlo and Lotter, André F. and Sturm, Michael},\n\tmonth = apr,\n\tyear = {2008},\n\tkeywords = {\\#nosource},\n\tpages = {283--299},\n}\n\n\n\n\n\n We analysed a 42 cm long sediment record from Lej da la Tscheppa, a high-altitude lake (2,616 m a.s.l.) in the Upper Engadine valley (Switzerland) for subfossil diatoms, chironomids and pollen. The chronology of the top 21 cm of the record was established using 210Pb analysis using a constant-rate-of-supply model, and validated with 137Cs measurements and the content of spheroidal carbonaceous particles. A tentative chronology for the lower part of the core was obtained through extrapolation of the sedimentation rates in the uppermost part of the record. Pollen assemblages in the record reflect regional changes in forestation and land-use patterns in the Upper Engadine valley and show no evidence of significant local human activity in the lake’s catchment. Diatom assemblages record a distinct increase in planktonic taxa since the early 19th century, suggesting a decrease in the duration of ice-cover. In contrast, chironomid assemblages remained stable during a large part of the record. We applied an established chironomid-based July air temperature transfer function and a newly developed diatom-based spring air temperature transfer function to reconstruct past seasonal air temperature changes at Lej da la Tscheppa. The reconstructions indicate a diatom-inferred warming trend in spring temperatures during the past ca. 400 years, whereas chironomid-inferred summer temperatures suggest a slight cooling trend. These biota-based reconstructions are in good agreement with the centennial-scale temperature trend in an independent reconstruction of regional temperatures in the Upper Engadine region based on instrumental records and documentary proxy evidence from the Alps. Our results suggest that, in high-altitude lakes, independent chironomid- and diatom-based seasonal temperature reconstruction is possible and can be successfully used to track seasonal temperature trends.\n
\n\n\n\n \n\n \n \n \n \n \n \n An explorative study of mercury export from a thawing palsa mire.\n \n \n \n \n\n\n \n Klaminder, J.; Yoo, K.; Rydberg, J.; and Giesler, R.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 113(G4): G04034. December 2008.\n \n\n\n\n
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\n\n\n@article{klaminder_explorative_2008,\n\ttitle = {An explorative study of mercury export from a thawing palsa mire},\n\tvolume = {113},\n\tissn = {2156-2202},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2008JG000776/abstract},\n\tdoi = {10.1029/2008JG000776},\n\tabstract = {Thawing of permafrost and a subsequent accelerated loss of mercury from the soil constitute a possible threat to the quality of high-latitude surface waters. In this paper we estimate the export of mercury generated by a thawing palsa mire in northern Sweden, by assessing net mercury storage changes along thermokarst erosion gradients. Lower mercury inventories in inundated hummocks covered by water (≤3.1 mg Hg m−2) than in noneroding hummocks (between 5.5 and 8 mg Hg m−2) suggests a release of ∼40–95\\% of the mercury pool from hummock peat experiencing subsidence and submerging. The documented expansion of submerged areas between 1970 and 2000 in the studied system indicates that permafrost thawing has initiated a mobilization of 34 to 50 g mercury. We stress the need of further assessing the fate of this mercury because the size of the mobilized mercury pool might be highly significant for subarctic surface waters.},\n\tlanguage = {en},\n\tnumber = {G4},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Klaminder, Jonatan and Yoo, Kyungsoo and Rydberg, Johan and Giesler, Reiner},\n\tmonth = dec,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Arctic, Biogeochemical cycles, processes, and modeling, Climate dynamics, Hg, Metals, Permafrost, cryosphere, and high-latitude processes, climate, mercury},\n\tpages = {G04034},\n}\n\n\n\n\n\n Thawing of permafrost and a subsequent accelerated loss of mercury from the soil constitute a possible threat to the quality of high-latitude surface waters. In this paper we estimate the export of mercury generated by a thawing palsa mire in northern Sweden, by assessing net mercury storage changes along thermokarst erosion gradients. Lower mercury inventories in inundated hummocks covered by water (≤3.1 mg Hg m−2) than in noneroding hummocks (between 5.5 and 8 mg Hg m−2) suggests a release of ∼40–95% of the mercury pool from hummock peat experiencing subsidence and submerging. The documented expansion of submerged areas between 1970 and 2000 in the studied system indicates that permafrost thawing has initiated a mobilization of 34 to 50 g mercury. We stress the need of further assessing the fate of this mercury because the size of the mobilized mercury pool might be highly significant for subarctic surface waters.\n
\n\n\n\n \n\n \n \n \n \n \n \n Sources of stream water sulfate during the spring snowmelt in boreal streams: Evidence from δ34S isotope measurements.\n \n \n \n \n\n\n \n Mörth, C.; Laudon, H.; Mellqvist, E.; Torssander, P.; and Giesler, R.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences, 113(G1): G01005. March 2008.\n \n\n\n\n
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\n\n\n@article{morth_sources_2008,\n\ttitle = {Sources of stream water sulfate during the spring snowmelt in boreal streams: {Evidence} from δ{34S} isotope measurements},\n\tvolume = {113},\n\tissn = {2156-2202},\n\tshorttitle = {Sources of stream water sulfate during the spring snowmelt in boreal streams},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1029/2007JG000457/abstract},\n\tdoi = {10.1029/2007JG000457},\n\tabstract = {Episodic hydrological events, such as snowmelt during spring, have a marked effect on stream water chemistry. Here we investigated how spring snowmelt affected δ34S values of sulfate in six streams situated in northern Sweden. Four streams had high δ34SSO4 values during base flow with values ranging from +11.9 to +8.6‰. During snowmelt the δ34SSO4 decreased to around +6‰. In one of the streams and in the forested upper reaches of a second stream, δ34SSO4 values were close to +5‰ during base flow and decreased to about +3.8‰ during the spring snowmelt. One stream, which drained cultivated postglacial sediments dominated by acid sulfuric soils, was differentiated from the other streams by low δ34SSO4 values (−5.0‰ to −0.5‰). We could identify two stream water SO4 sources: sedimentary sulfides and anthropogenic S. Bacterial dissimilatory sulfate reduction was identified as an important process affecting stream water δ34SSO4 values and suggests that in this boreal landscape, peatlands and possibly riparian zones have a large influence on the biogeochemistry of SO42− during base flow conditions. Our results suggest that during the spring snowmelt, snow S and desorbing SO4 of mainly anthropogenic origin are the two major S sources in four of the investigated streams. Two streams in forested areas also indicate that reoxidation of reduced S may be released during the spring flood. The stream in the cultivated area was found to be strongly influenced by the acid sulfuric soils independent of stream flow conditions.},\n\tlanguage = {en},\n\tnumber = {G1},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Mörth, Carl-Magnus and Laudon, Hjalmar and Mellqvist, Elin and Torssander, Peter and Giesler, Reiner},\n\tmonth = mar,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Biogeochemical cycles, processes, and modeling, Catchment, Chemistry of fresh water, Stable isotope geochemistry, Sulfur cycling, boreal, spring snowmelt, stream water, sulfate, sulfur isotopes},\n\tpages = {G01005},\n}\n\n\n\n\n\n Episodic hydrological events, such as snowmelt during spring, have a marked effect on stream water chemistry. Here we investigated how spring snowmelt affected δ34S values of sulfate in six streams situated in northern Sweden. Four streams had high δ34SSO4 values during base flow with values ranging from +11.9 to +8.6‰. During snowmelt the δ34SSO4 decreased to around +6‰. In one of the streams and in the forested upper reaches of a second stream, δ34SSO4 values were close to +5‰ during base flow and decreased to about +3.8‰ during the spring snowmelt. One stream, which drained cultivated postglacial sediments dominated by acid sulfuric soils, was differentiated from the other streams by low δ34SSO4 values (−5.0‰ to −0.5‰). We could identify two stream water SO4 sources: sedimentary sulfides and anthropogenic S. Bacterial dissimilatory sulfate reduction was identified as an important process affecting stream water δ34SSO4 values and suggests that in this boreal landscape, peatlands and possibly riparian zones have a large influence on the biogeochemistry of SO42− during base flow conditions. Our results suggest that during the spring snowmelt, snow S and desorbing SO4 of mainly anthropogenic origin are the two major S sources in four of the investigated streams. Two streams in forested areas also indicate that reoxidation of reduced S may be released during the spring flood. The stream in the cultivated area was found to be strongly influenced by the acid sulfuric soils independent of stream flow conditions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Soil feedback on plant growth in a sub-arctic grassland as a result of repeated defoliation.\n \n \n \n \n\n\n \n Sørensen, L. I.; Kytöviita, M.; Olofsson, J.; and Mikola, J.\n\n\n \n\n\n\n Soil Biology and Biochemistry, 40(11): 2891–2897. November 2008.\n \n\n\n\n
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\n\n\n@article{sorensen_soil_2008,\n\ttitle = {Soil feedback on plant growth in a sub-arctic grassland as a result of repeated defoliation},\n\tvolume = {40},\n\tissn = {0038-0717},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0038071708002836},\n\tdoi = {10.1016/j.soilbio.2008.08.009},\n\tabstract = {In the long term, defoliation of plants can be hypothesized to decrease plant carbon supply to soil decomposers and thus decrease decomposer abundance and nutrient mineralization in the soil. To test whether defoliation creates changes in soil that can feedback to plant growth, we collected soil from sub-arctic grassland plots that had been either defoliated or non-defoliated for three years and followed the growth of different plant species combinations in these soils in greenhouse conditions. Plant N acquisition and plant growth were lower in the soil collected from the defoliated field plots than in the soil collected from the non-defoliated plots. This response did not depend on the species composition or richness of the tested plant community. In the field, defoliation decreased net nitrogen mineralization. Despite the negative effect of decreased nutrient mineralization rate on plant growth and N accumulation in the greenhouse test, the aboveground abundance of most plant species was not affected by defoliation in the field. This indicates that plants in these sub-arctic grasslands can at least temporarily overcome defoliation-induced decrease in soil nutrient availability. To our knowledge, our results are the first direct evidence that defoliation can induce changes in the soil that negatively feedback to plant growth and N accumulation. This finding indicates that, especially in arctic and sub-arctic grasslands where nutrient mineralization rates are inherently low, soil feedbacks can have an important role in the outcome of herbivore–plant interactions.},\n\tnumber = {11},\n\turldate = {2017-02-07},\n\tjournal = {Soil Biology and Biochemistry},\n\tauthor = {Sørensen, Louise I. and Kytöviita, Minna-Maarit and Olofsson, Johan and Mikola, Juha},\n\tmonth = nov,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Aboveground–belowground interactions, Soil feedbacks, Soil fertility, Sub-arctic ecosystem, defoliation},\n\tpages = {2891--2897},\n}\n\n\n\n\n\n In the long term, defoliation of plants can be hypothesized to decrease plant carbon supply to soil decomposers and thus decrease decomposer abundance and nutrient mineralization in the soil. To test whether defoliation creates changes in soil that can feedback to plant growth, we collected soil from sub-arctic grassland plots that had been either defoliated or non-defoliated for three years and followed the growth of different plant species combinations in these soils in greenhouse conditions. Plant N acquisition and plant growth were lower in the soil collected from the defoliated field plots than in the soil collected from the non-defoliated plots. This response did not depend on the species composition or richness of the tested plant community. In the field, defoliation decreased net nitrogen mineralization. Despite the negative effect of decreased nutrient mineralization rate on plant growth and N accumulation in the greenhouse test, the aboveground abundance of most plant species was not affected by defoliation in the field. This indicates that plants in these sub-arctic grasslands can at least temporarily overcome defoliation-induced decrease in soil nutrient availability. To our knowledge, our results are the first direct evidence that defoliation can induce changes in the soil that negatively feedback to plant growth and N accumulation. This finding indicates that, especially in arctic and sub-arctic grasslands where nutrient mineralization rates are inherently low, soil feedbacks can have an important role in the outcome of herbivore–plant interactions.\n
\n\n\n\n \n\n \n \n \n \n \n Spatial patterns and dynamic responses of arctic food webs corroborate the exploitation ecosystems hypothesis (EEH).\n \n \n \n\n\n \n Aunapuu, M.; Dahlgren, J.; Oksanen, T.; Grellmann, D.; Oksanen, L.; Olofsson, J.; Rammul, U.; Schneider, M.; Johansen, B.; and Hygen, H. O.\n\n\n \n\n\n\n American Naturalist, 171(2): 249–262. February 2008.\n \n\n\n\n
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\n\n\n@article{aunapuu_spatial_2008,\n\ttitle = {Spatial patterns and dynamic responses of arctic food webs corroborate the exploitation ecosystems hypothesis ({EEH})},\n\tvolume = {171},\n\tissn = {0003-0147},\n\tdoi = {10.1086/524951},\n\tabstract = {According to the exploitation ecosystems hypothesis (EEH), productive terrestrial ecosystems are characterized by community-level trophic cascades, whereas unproductive ecosystems harbor food-limited grazers, which regulate community-level plant biomass. We tested this hypothesis along arctic-alpine productivity gradients at the Joatka field base, Finnmark, Norway. In unproductive habitats, mammalian predators were absent and plant biomass was constant, whereas herbivore biomass varied, reflecting the productivity of the habitat. In productive habitats, predatory mammals were persistently present and plant biomass varied in space, but herbivore biomass did not. Plant biomass of productive tundra scrublands declined by 40\\% when vegetation blocks were transferred to predation-free islands. Corresponding transfer to herbivore-free islands triggered an increase in plant biomass. Fertilization of an unproductive tundra heath resulted in a fourfold increase in rodent density and a corresponding increase in winter grazing activity, whereas the total aboveground plant biomass remained unchanged. These results corroborate the predictions of the EEH, implying that the endotherm community and the vegetation of the North European tundra behaves dynamically as if each trophic level consisted of a single population, in spite of local co-occurrence of {\\textgreater} 20 plant species representing different major taxonomic groups, growth forms, and defensive strategies.},\n\tlanguage = {English},\n\tnumber = {2},\n\tjournal = {American Naturalist},\n\tauthor = {Aunapuu, Maano and Dahlgren, Jonas and Oksanen, Tarja and Grellmann, Doris and Oksanen, Lauri and Olofsson, Johan and Rammul, Uellar and Schneider, Michael and Johansen, Bernt and Hygen, Hans Olav},\n\tmonth = feb,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Arctic, Plant communities, habitat selection, herbivory, long-term, north fennoscandian tundra, plant community, population-dynamics, predation, primary productivity, real differences, trophic cascades, tundra vegetation, white-tailed deer, yellowstone-national-park},\n\tpages = {249--262},\n}\n\n\n\n\n\n According to the exploitation ecosystems hypothesis (EEH), productive terrestrial ecosystems are characterized by community-level trophic cascades, whereas unproductive ecosystems harbor food-limited grazers, which regulate community-level plant biomass. We tested this hypothesis along arctic-alpine productivity gradients at the Joatka field base, Finnmark, Norway. In unproductive habitats, mammalian predators were absent and plant biomass was constant, whereas herbivore biomass varied, reflecting the productivity of the habitat. In productive habitats, predatory mammals were persistently present and plant biomass varied in space, but herbivore biomass did not. Plant biomass of productive tundra scrublands declined by 40% when vegetation blocks were transferred to predation-free islands. Corresponding transfer to herbivore-free islands triggered an increase in plant biomass. Fertilization of an unproductive tundra heath resulted in a fourfold increase in rodent density and a corresponding increase in winter grazing activity, whereas the total aboveground plant biomass remained unchanged. These results corroborate the predictions of the EEH, implying that the endotherm community and the vegetation of the North European tundra behaves dynamically as if each trophic level consisted of a single population, in spite of local co-occurrence of \\textgreater 20 plant species representing different major taxonomic groups, growth forms, and defensive strategies.\n
\n\n\n\n \n\n \n \n \n \n \n Is there a chronological record of atmospheric mercury and lead deposition preserved in the mor layer (O-horizon) of boreal forest soils?.\n \n \n \n\n\n \n Klaminder, J.; Bindler, R.; Rydberg, J.; and Renberg, I.\n\n\n \n\n\n\n Geochimica Et Cosmochimica Acta, 72(3): 703–712. February 2008.\n \n\n\n\n
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\n\n\n@article{klaminder_is_2008,\n\ttitle = {Is there a chronological record of atmospheric mercury and lead deposition preserved in the mor layer ({O}-horizon) of boreal forest soils?},\n\tvolume = {72},\n\tissn = {0016-7037},\n\tdoi = {10.1016/j.gca.2007.10.030},\n\tabstract = {The organic horizon (the mor layer) of podzolized boreal forest soils has accumulated atmospheric fallout of mercury and lead over centuries, resulting in current concentrations close to levels where negative effects on soil biota are thought to occur. To what extent the pollution history is preserved in the stratigraphy of this horizon is not well known. In this study we asses whether the chronology of a large historic pulse of atmospheric pollution emitted from the Ronnskar smelter in northern Sweden, particularly between 1950 and 1980, is preserved within the stratigraphy of the mor layer, which is typically 5-cm thick. Vertical sub-sampling ({\\textless}= 5 mm) of five mor profiles sampled along a 100-km pollution gradient away from the smelter are analyzed for mercury and lead concentrations, spheroidal carbonaceous particles from fossil fuel combustion (SCPs) and stable lead isotopes (Pb-206/Pb-207 and Pb-208/Pb-207). Their vertical distribution is compared with the temporal variations in atmospheric inputs reconstructed for the last similar to 100 years from analyses of an ombrotrophic peat core and a varved take sediment core sampled within a distance of 50 km of the smelter. The mor profiles situated {\\textless}= 12 km from the smelter record the pollution history of the smelter. There is a 20 to 40-times enrichment of Hg, Pb and SCP at the transition in the O-horizon from the F- to H-layer compared to the basal part and a distinct peak in the Pb-206/Pb-207 ratio (similar to 1.22) in the F-layer. The mor profiles situated outside the historical contamination range of the smelter (80 and 100 km away) record no obvious influence from the Ronnskar smelter, instead their vertical Pb-206/Pb-207 profiles follow the general regional pollution history in northern Sweden. We conclude that the mor layer preserves a record of atmospheric Hg, Pb and SCP inputs and due to low leaching rates this organic horizon serves as a semi-archive of atmospheric Hg and Pb pollution. We stress the need of including this property in the existing 'black-box' models predicting the fate of Hg and Pb within contaminated boreal forest soils. (c) 2008 Elsevier Ltd. All rights reserved.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Geochimica Et Cosmochimica Acta},\n\tauthor = {Klaminder, Jonatan and Bindler, Richard and Rydberg, Johan and Renberg, Ingernar},\n\tmonth = feb,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Ecosystems, Peat bog, concentration profiles, fluxes, isotopic composition, mediterranean soils, northern sweden, ombrotrophic bogs, pollution, trends},\n\tpages = {703--712},\n}\n\n\n\n\n\n The organic horizon (the mor layer) of podzolized boreal forest soils has accumulated atmospheric fallout of mercury and lead over centuries, resulting in current concentrations close to levels where negative effects on soil biota are thought to occur. To what extent the pollution history is preserved in the stratigraphy of this horizon is not well known. In this study we asses whether the chronology of a large historic pulse of atmospheric pollution emitted from the Ronnskar smelter in northern Sweden, particularly between 1950 and 1980, is preserved within the stratigraphy of the mor layer, which is typically 5-cm thick. Vertical sub-sampling (\\textless= 5 mm) of five mor profiles sampled along a 100-km pollution gradient away from the smelter are analyzed for mercury and lead concentrations, spheroidal carbonaceous particles from fossil fuel combustion (SCPs) and stable lead isotopes (Pb-206/Pb-207 and Pb-208/Pb-207). Their vertical distribution is compared with the temporal variations in atmospheric inputs reconstructed for the last similar to 100 years from analyses of an ombrotrophic peat core and a varved take sediment core sampled within a distance of 50 km of the smelter. The mor profiles situated \\textless= 12 km from the smelter record the pollution history of the smelter. There is a 20 to 40-times enrichment of Hg, Pb and SCP at the transition in the O-horizon from the F- to H-layer compared to the basal part and a distinct peak in the Pb-206/Pb-207 ratio (similar to 1.22) in the F-layer. The mor profiles situated outside the historical contamination range of the smelter (80 and 100 km away) record no obvious influence from the Ronnskar smelter, instead their vertical Pb-206/Pb-207 profiles follow the general regional pollution history in northern Sweden. We conclude that the mor layer preserves a record of atmospheric Hg, Pb and SCP inputs and due to low leaching rates this organic horizon serves as a semi-archive of atmospheric Hg and Pb pollution. We stress the need of including this property in the existing 'black-box' models predicting the fate of Hg and Pb within contaminated boreal forest soils. (c) 2008 Elsevier Ltd. All rights reserved.\n
\n\n\n\n \n\n \n \n \n \n \n Characterization of iron(III) in organic soils using extended X-ray absorption fine structure spectroscopy.\n \n \n \n\n\n \n Karlsson, T.; Persson, P.; Skyllberg, U.; Morth, C.; and Giesler, R.\n\n\n \n\n\n\n Environmental Science & Technology, 42(15): 5449–5454. August 2008.\n \n\n\n\n
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\n\n\n@article{karlsson_characterization_2008,\n\ttitle = {Characterization of iron({III}) in organic soils using extended {X}-ray absorption fine structure spectroscopy},\n\tvolume = {42},\n\tissn = {0013-936X},\n\tdoi = {10.1021/es800322j},\n\tabstract = {The distribution of different iron (Fe) species in soils, sediments, and surface waters has a large influence on the mobility and availability of Fe, other nutrients, and potentially toxic trace elements. However, the knowledge about the specific forms of Fe that occurs in these systems is limited, especially regarding associations of Fe with natural organic matter (NOM). In this study, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to characterize Fe(III) in organic soils (pH 4.6-6.0) with varying natural Fe content. The EXAFS data were subjected to wavelet transform analysis, to facilitate the identification of the nature of backscattering atoms, and to conventional EXAFS data fitting. The collective results showed the existence of two pools of iron: mononuclear Fe(III)-NOM complexes and precipitated Fe(III) (hydr)oxides. In the soil with lowest pH (4.6) and Fe content mononuclear organic complexes were the completely dominating fraction whereas in soils with higher pH and Fe content increasing amounts of Fe (hydr)oxides were detected. These results are of environmental importance, as the different iron pools most likely have markedly different reactivities.},\n\tlanguage = {English},\n\tnumber = {15},\n\tjournal = {Environmental Science \\& Technology},\n\tauthor = {Karlsson, Torbjorn and Persson, Per and Skyllberg, Ulf and Morth, Carl-Magnus and Giesler, Reiner},\n\tmonth = aug,\n\tyear = {2008},\n\tkeywords = {\\#nosource, Adsorption, alpha-feooh, binding, complexes, exafs spectroscopy, fe, interface, iron speciation, matter, spectra},\n\tpages = {5449--5454},\n}\n\n\n\n\n\n The distribution of different iron (Fe) species in soils, sediments, and surface waters has a large influence on the mobility and availability of Fe, other nutrients, and potentially toxic trace elements. However, the knowledge about the specific forms of Fe that occurs in these systems is limited, especially regarding associations of Fe with natural organic matter (NOM). In this study, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to characterize Fe(III) in organic soils (pH 4.6-6.0) with varying natural Fe content. The EXAFS data were subjected to wavelet transform analysis, to facilitate the identification of the nature of backscattering atoms, and to conventional EXAFS data fitting. The collective results showed the existence of two pools of iron: mononuclear Fe(III)-NOM complexes and precipitated Fe(III) (hydr)oxides. In the soil with lowest pH (4.6) and Fe content mononuclear organic complexes were the completely dominating fraction whereas in soils with higher pH and Fe content increasing amounts of Fe (hydr)oxides were detected. These results are of environmental importance, as the different iron pools most likely have markedly different reactivities.\n
\n\n\n\n \n\n \n \n \n \n \n Establishment of boreal forest species in alpine dwarf-shrub heath in subarctic Sweden.\n \n \n \n\n\n \n Sundqvist, M. K.; Bjork, R. G.; and Molau, U.\n\n\n \n\n\n\n Plant Ecology & Diversity, 1(1): 67–75. 2008.\n 00027\n\n\n\n
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\n\n\n@article{sundqvist_establishment_2008,\n\ttitle = {Establishment of boreal forest species in alpine dwarf-shrub heath in subarctic {Sweden}},\n\tvolume = {1},\n\tissn = {1755-0874},\n\tdoi = {10.1080/17550870802273395},\n\tabstract = {Background: Saplings of mountain birch ( Betula pubescens ssp. czerepanovii) have established in pockets of dwarf-shrub heath approximately 250 m above the treeline in the Latnjavagge Valley, northern Sweden. Aim: We examined if the establishment of these mountain birch outposts was related to favourable local microclimate, and if birch establishment has affected the surrounding vegetation, changing it from dwarf-shrub heath to more akin to birch forest floor. Methods: Daily mean and mean maximum temperatures were compared for two sites in the dwarf-shrub heath ( 990 m a. s. l., few birch saplings; 1060 m a. s. l., numerous birch saplings) between January 2005 and June 2006. The cover-abundance of vascular plants was estimated in sample plots in dwarf-shrub heath with mountain birch, dwarf-shrub heath without mountain birch, in heath between the upper limit of closed mountain birch forest and the treeline, and in closed mountain birch forest. Species composition and diversity were statistically compared. The presence in the dwarf-shrub heath of boreal montane species other than birch was also noted. Results: The higher elevation site, containing a higher density of birch, had a significantly higher growing season temperature than the lower elevation site. There was a significant difference in plant community composition between the alpine heath plots containing mountain birch saplings and plots without mountain birch, alpine heath with birch being more similar to the plots of the treeline ecotone and the birch forest than to alpine heath without birch. No significant difference in species diversity among plots in dwarf-shrub heath was found and species diversity increased with altitude. A number of montane species were observed in the dwarf-shrub heath, however, their distribution was not associated with that of the mountain birch. Conclusions: This study provides evidence for favourable microclimate being a key driver for the establishment of mountain birch above the treeline. In addition, the results imply that the composition of the dwarf-shrub heath changes after the establishment of mountain birch to a plant community whose composition points towards a birch forest.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Plant Ecology \\& Diversity},\n\tauthor = {Sundqvist, Maja K. and Bjork, Robert G. and Molau, Ulf},\n\tyear = {2008},\n\tnote = {00027},\n\tkeywords = {\\#nosource, Climate change, microclimate, species composition, species diversity, treeline},\n\tpages = {67--75},\n}\n\n\n\n\n\n Background: Saplings of mountain birch ( Betula pubescens ssp. czerepanovii) have established in pockets of dwarf-shrub heath approximately 250 m above the treeline in the Latnjavagge Valley, northern Sweden. Aim: We examined if the establishment of these mountain birch outposts was related to favourable local microclimate, and if birch establishment has affected the surrounding vegetation, changing it from dwarf-shrub heath to more akin to birch forest floor. Methods: Daily mean and mean maximum temperatures were compared for two sites in the dwarf-shrub heath ( 990 m a. s. l., few birch saplings; 1060 m a. s. l., numerous birch saplings) between January 2005 and June 2006. The cover-abundance of vascular plants was estimated in sample plots in dwarf-shrub heath with mountain birch, dwarf-shrub heath without mountain birch, in heath between the upper limit of closed mountain birch forest and the treeline, and in closed mountain birch forest. Species composition and diversity were statistically compared. The presence in the dwarf-shrub heath of boreal montane species other than birch was also noted. Results: The higher elevation site, containing a higher density of birch, had a significantly higher growing season temperature than the lower elevation site. There was a significant difference in plant community composition between the alpine heath plots containing mountain birch saplings and plots without mountain birch, alpine heath with birch being more similar to the plots of the treeline ecotone and the birch forest than to alpine heath without birch. No significant difference in species diversity among plots in dwarf-shrub heath was found and species diversity increased with altitude. A number of montane species were observed in the dwarf-shrub heath, however, their distribution was not associated with that of the mountain birch. Conclusions: This study provides evidence for favourable microclimate being a key driver for the establishment of mountain birch above the treeline. In addition, the results imply that the composition of the dwarf-shrub heath changes after the establishment of mountain birch to a plant community whose composition points towards a birch forest.\n
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\n \n \n\n \n \n \n \n \n Effects of climate, fire and vegetation development on Holocene changes in total organic carbon concentration in three boreal forest lakes in northern Sweden.\n \n \n \n\n\n \n Rosén, P; and Hammarlund, D\n\n\n \n\n\n\n Biogeosciences Discussions, 4(2): 1329–1352. 2007.\n 00047\n\n\n\n
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\n\n\n\n@article{rosen_effects_2007,\n\ttitle = {Effects of climate, fire and vegetation development on {Holocene} changes in total organic carbon concentration in three boreal forest lakes in northern {Sweden}},\n\tvolume = {4},\n\tlanguage = {en},\n\tnumber = {2},\n\tjournal = {Biogeosciences Discussions},\n\tauthor = {Rosén, P and Hammarlund, D},\n\tyear = {2007},\n\tnote = {00047},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {1329--1352},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n Substitution of top predators: effects of pike invasion in a subarctic lake.\n \n \n \n\n\n \n Byström, P.; Karlsson, J.; Nilsson, P.; Van Kooten, T.; Ask, J.; and Olofsson, F.\n\n\n \n\n\n\n Freshwater Biology, 52(7): 1271–1280. July 2007.\n 00074\n\n\n\n
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\n\n\n@article{bystrom_substitution_2007,\n\ttitle = {Substitution of top predators: effects of pike invasion in a subarctic lake},\n\tvolume = {52},\n\tissn = {0046-5070},\n\tshorttitle = {Substitution of top predators},\n\tdoi = {10.1111/j.1365-2427.2007.01763.x},\n\tabstract = {1. Invasions of top predators may have strong cascading effects in ecosystems affecting both prey species abundance and lower trophic levels. A recently discussed factor that may enhance species invasion is climate change and in this context, we studied the effects of an invasion of northern pike into a subarctic lake ecosystem formerly inhabited by the native top predator Arctic char and its prey fish, ninespined stickleback. 2. Our study demonstrated a strong change in fish community composition from a system with Arctic char as top predator and high densities of sticklebacks to a system with northern pike as top predator and very low densities of sticklebacks. A combination of both predation and competition from pike is the likely cause of the extinction of char. 3. The change in top predator species also cascaded down to primary consumers as both zooplankton and predator-sensitive macroinvertebrates increased in abundance. 4. Although the pike invasion coincided with increasing summer temperatures in the study area we have no conclusive evidence that the temperature increase is the causal mechanism behind the pike invasion. But still, our study provides possible effects of future pike invasions in mountain lakes related to climate change. We suggest that future pike invasions will have strong effects in lake ecosystems, both by replacing native top consumers and through cascading effects on lower trophic levels.},\n\tlanguage = {English},\n\tnumber = {7},\n\tjournal = {Freshwater Biology},\n\tauthor = {Byström, Pär and Karlsson, Jan and Nilsson, Per and Van Kooten, Tobias and Ask, Jenny and Olofsson, Frans},\n\tmonth = jul,\n\tyear = {2007},\n\tnote = {00074},\n\tkeywords = {\\#nosource, Arctic char, brown trout, cascading effects, charr salvelinus-alpinus, climate change, climate-change, communities, esox-lucius, fish introductions, intraguild predation, lake ecosystems, long-term, ninespined stickleback, northern pike, perch perca-fluviatilis, salmo-trutta, top predator invasions},\n\tpages = {1271--1280},\n}\n\n\n\n\n\n 1. Invasions of top predators may have strong cascading effects in ecosystems affecting both prey species abundance and lower trophic levels. A recently discussed factor that may enhance species invasion is climate change and in this context, we studied the effects of an invasion of northern pike into a subarctic lake ecosystem formerly inhabited by the native top predator Arctic char and its prey fish, ninespined stickleback. 2. Our study demonstrated a strong change in fish community composition from a system with Arctic char as top predator and high densities of sticklebacks to a system with northern pike as top predator and very low densities of sticklebacks. A combination of both predation and competition from pike is the likely cause of the extinction of char. 3. The change in top predator species also cascaded down to primary consumers as both zooplankton and predator-sensitive macroinvertebrates increased in abundance. 4. Although the pike invasion coincided with increasing summer temperatures in the study area we have no conclusive evidence that the temperature increase is the causal mechanism behind the pike invasion. But still, our study provides possible effects of future pike invasions in mountain lakes related to climate change. We suggest that future pike invasions will have strong effects in lake ecosystems, both by replacing native top consumers and through cascading effects on lower trophic levels.\n
\n\n\n\n \n\n \n \n \n \n \n \n Pelagic and benthic net production of dissolved inorganic carbon in an unproductive subarctic lake.\n \n \n \n \n\n\n \n Åberg, J.; Jansson, M.; Karlsson, J.; Nääs, K.; and Jonsson, A.\n\n\n \n\n\n\n Freshwater Biology, 52(3): 549–560. March 2007.\n 00022\n\n\n\n
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\n\n\n@article{aberg_pelagic_2007,\n\ttitle = {Pelagic and benthic net production of dissolved inorganic carbon in an unproductive subarctic lake},\n\tvolume = {52},\n\tissn = {1365-2427},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2427.2007.01725.x/abstract},\n\tdoi = {10.1111/j.1365-2427.2007.01725.x},\n\tabstract = {1. Both the pelagic and benthic net dissolved inorganic carbon (DIC) productions were measured in situ on four occasions from June to September 2004, in the unproductive Lake Diktar-Erik in subarctic Sweden. The stable isotopic signal (δ13C) of respired organic material was estimated from hypolimnion water data and data from a laboratory incubation using epilimnion water. 2. Both pelagic and benthic habitats were net heterotrophic during the study period, with a total net DIC production of 416 mg C m−2 day−1, of which the pelagic habitat contributed approximately 85\\%. The net DIC production decreased with depth both in the pelagic water and in the sediments, and most of the net DIC production occurred in the upper water column. 3. Temporal variations in both pelagic and benthic DIC production were small, although we observed a significant decrease in pelagic net DIC production after the autumn turnover. Water temperature was the single most important factor explaining temporal and vertical variations in pelagic DIC production. No single factor explained more than 10\\% of the benthic net DIC production, which probably was regulated by several interacting factors. 4. Pelagic DIC production, and thus most of the whole-lake net production of DIC, was mainly due to the respiration of allochthonous organic carbon. Stable isotope data inferred that nearly 100\\% of accumulated DIC in the hypolimnion water had an allochthonous carbon source. Similarly, in the laboratory incubation using epilimnion water, c. 85\\% of accumulated DIC was indicated to have an allochthonous organic carbon source.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-06},\n\tjournal = {Freshwater Biology},\n\tauthor = {Åberg, Jan and Jansson, Mats and Karlsson, Jan and Nääs, Klockar-Jenny and Jonsson, Anders},\n\tmonth = mar,\n\tyear = {2007},\n\tnote = {00022},\n\tkeywords = {\\#nosource, allochthonous carbon, carbon dioxide, dissolved inorganic carbon, respiration, stable isotopes},\n\tpages = {549--560},\n}\n\n\n\n\n\n 1. Both the pelagic and benthic net dissolved inorganic carbon (DIC) productions were measured in situ on four occasions from June to September 2004, in the unproductive Lake Diktar-Erik in subarctic Sweden. The stable isotopic signal (δ13C) of respired organic material was estimated from hypolimnion water data and data from a laboratory incubation using epilimnion water. 2. Both pelagic and benthic habitats were net heterotrophic during the study period, with a total net DIC production of 416 mg C m−2 day−1, of which the pelagic habitat contributed approximately 85%. The net DIC production decreased with depth both in the pelagic water and in the sediments, and most of the net DIC production occurred in the upper water column. 3. Temporal variations in both pelagic and benthic DIC production were small, although we observed a significant decrease in pelagic net DIC production after the autumn turnover. Water temperature was the single most important factor explaining temporal and vertical variations in pelagic DIC production. No single factor explained more than 10% of the benthic net DIC production, which probably was regulated by several interacting factors. 4. Pelagic DIC production, and thus most of the whole-lake net production of DIC, was mainly due to the respiration of allochthonous organic carbon. Stable isotope data inferred that nearly 100% of accumulated DIC in the hypolimnion water had an allochthonous carbon source. Similarly, in the laboratory incubation using epilimnion water, c. 85% of accumulated DIC was indicated to have an allochthonous organic carbon source.\n
\n\n\n\n \n\n \n \n \n \n \n \n Differences in efficiency of carbon transfer from dissolved organic carbon to two zooplankton groups: an enclosure experiment in an oligotrophic lake.\n \n \n \n \n\n\n \n Karlsson, J.; Lymer, D.; Vrede, K.; and Jansson, M.\n\n\n \n\n\n\n Aquatic Sciences, 69(1): 108–114. March 2007.\n 00029\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{karlsson_differences_2007,\n\ttitle = {Differences in efficiency of carbon transfer from dissolved organic carbon to two zooplankton groups: an enclosure experiment in an oligotrophic lake},\n\tvolume = {69},\n\tissn = {1015-1621, 1420-9055},\n\tshorttitle = {Differences in efficiency of carbon transfer from dissolved organic carbon to two zooplankton groups},\n\turl = {http://link.springer.com/article/10.1007/s00027-007-0913-2},\n\tdoi = {10.1007/s00027-007-0913-2},\n\tabstract = {.We added dissolved organic carbon (C) in various amounts to 6 enclosures in an oligotrophic subarctic lake to assess how bacterioplankton growth on dissolved organic C affects the growth of calanoid copepod (Eudiaptomus graciloides) and cladoceran (Daphnia longispina) zooplankton. Organic C was added as glucose (12.5 to 400 µgC L−1d−1) and was isotopically distinct (−11.7 ‰) from lakewater organic C ({\\textless}−27.2‰). All enclosures were also enriched with the same amounts of inorganic nitrogen (30 µgN L−1d−1 as NH4NO3) and inorganic phosphorus (2 µgP L−1d−1 as Na3PO4). The results showed a direct relationship between bacterial growth on dissolved organic C and incorporation of bacterial biomass into crustacean zooplankton. After 9 days, D. longispina and E. graciloides contained glucose-C in all treatments and the incorporation of glucose-C by zooplankton was strongly correlated with bacterial growth on glucose-C.δ15N data revealed different trophic positions of the two crustaceans, suggesting that D. longispina fed directly on bacteria while E. graciloides incorporated bacterial C by consumption of bacterivorus protozoans. Greater incorporation of glucose-C in D. longispina than in E. graciloides was explained by higher individual growth rates in D. longispina, and this difference between the two zooplankters increased as the bacterial production increased. Thus, the results show that the transfer of dissolved organic C through the food web can be more efficient via cladocerans than via calanoid copepods and that the effect becomes more pronounced as bacterial energy mobilization increases.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-06},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Karlsson, Jan and Lymer, David and Vrede, Katarina and Jansson, Mats},\n\tmonth = mar,\n\tyear = {2007},\n\tnote = {00029},\n\tkeywords = {\\#nosource, bacterial production, bacterioplankton, bacterioplankton production, calanoida copepoda, cladocera, food quality, growth, marine, matter, northern sweden, nutrient limitation, phytoplankton, systems, zooplankton growth},\n\tpages = {108--114},\n}\n\n\n\n\n\n .We added dissolved organic carbon (C) in various amounts to 6 enclosures in an oligotrophic subarctic lake to assess how bacterioplankton growth on dissolved organic C affects the growth of calanoid copepod (Eudiaptomus graciloides) and cladoceran (Daphnia longispina) zooplankton. Organic C was added as glucose (12.5 to 400 µgC L−1d−1) and was isotopically distinct (−11.7 ‰) from lakewater organic C (\\textless−27.2‰). All enclosures were also enriched with the same amounts of inorganic nitrogen (30 µgN L−1d−1 as NH4NO3) and inorganic phosphorus (2 µgP L−1d−1 as Na3PO4). The results showed a direct relationship between bacterial growth on dissolved organic C and incorporation of bacterial biomass into crustacean zooplankton. After 9 days, D. longispina and E. graciloides contained glucose-C in all treatments and the incorporation of glucose-C by zooplankton was strongly correlated with bacterial growth on glucose-C.δ15N data revealed different trophic positions of the two crustaceans, suggesting that D. longispina fed directly on bacteria while E. graciloides incorporated bacterial C by consumption of bacterivorus protozoans. Greater incorporation of glucose-C in D. longispina than in E. graciloides was explained by higher individual growth rates in D. longispina, and this difference between the two zooplankters increased as the bacterial production increased. Thus, the results show that the transfer of dissolved organic C through the food web can be more efficient via cladocerans than via calanoid copepods and that the effect becomes more pronounced as bacterial energy mobilization increases.\n
\n\n\n\n \n\n \n \n \n \n \n \n Different carbon support for respiration and secondary production in unproductive lakes.\n \n \n \n \n\n\n \n Karlsson, J.\n\n\n \n\n\n\n Oikos, 116(10): 1691–1696. October 2007.\n 00034\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{karlsson_different_2007,\n\ttitle = {Different carbon support for respiration and secondary production in unproductive lakes},\n\tvolume = {116},\n\tissn = {1600-0706},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.0030-1299.2007.15825.x/abstract},\n\tdoi = {10.1111/j.0030-1299.2007.15825.x},\n\tabstract = {This study investigates the allocation of allochthonous organic carbon (AlloOC) to pelagic respiration and biomass production in unproductive lakes. Metabolic process rates and stable isotopic composition (δ13C) of crustacean zooplankton and respired CO2 were measured in the epilimnion of 13 forest lakes in northern Sweden. The δ13C of zooplankton was low (−31.2 to −38.0‰) compared to that of respired CO2 (−28.4 to −30.6‰), implying that the relative importance of AlloOC was lower for zooplankton (ca 40\\%) than for respiration (ca 80\\%). Combining δ13C and carbon flux data revealed that a large amount of metabolized AlloOC was lost in respiration, compared to the amount transferred to zooplankton ({\\textless}3\\%). Thus, despite large respiratory losses, AlloOC was still important for zooplankton growth, implying a high supply of AlloOC in comparison to phytoplankton generated organic carbon in the lakes.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2017-02-06},\n\tjournal = {Oikos},\n\tauthor = {Karlsson, Jan},\n\tmonth = oct,\n\tyear = {2007},\n\tnote = {00034},\n\tkeywords = {\\#nosource},\n\tpages = {1691--1696},\n}\n\n\n\n\n\n This study investigates the allocation of allochthonous organic carbon (AlloOC) to pelagic respiration and biomass production in unproductive lakes. Metabolic process rates and stable isotopic composition (δ13C) of crustacean zooplankton and respired CO2 were measured in the epilimnion of 13 forest lakes in northern Sweden. The δ13C of zooplankton was low (−31.2 to −38.0‰) compared to that of respired CO2 (−28.4 to −30.6‰), implying that the relative importance of AlloOC was lower for zooplankton (ca 40%) than for respiration (ca 80%). Combining δ13C and carbon flux data revealed that a large amount of metabolized AlloOC was lost in respiration, compared to the amount transferred to zooplankton (\\textless3%). Thus, despite large respiratory losses, AlloOC was still important for zooplankton growth, implying a high supply of AlloOC in comparison to phytoplankton generated organic carbon in the lakes.\n
\n\n\n\n \n\n \n \n \n \n \n Mercury pollution trends in subarctic lakes in the northern Swedish mountains.\n \n \n \n\n\n \n Lindeberg, C.; Bindler, R.; Bigler, C.; Rosén, P.; and Renberg, I.\n\n\n \n\n\n\n Ambio, 36(5): 401–405. July 2007.\n \n\n\n\n
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\n\n\n@article{lindeberg_mercury_2007,\n\ttitle = {Mercury pollution trends in subarctic lakes in the northern {Swedish} mountains},\n\tvolume = {36},\n\tissn = {0044-7447},\n\tdoi = {10.1579/0044-7447(2007)36[401:MPTISL]2.0.CO;2},\n\tabstract = {Despite many years of research about mercury pollution, data concerning high-latitude regions of Europe are limited, particularly studies of long-term temporal trends. It is not clear whether the mercury load at high latitudes follows the recent decreasing trends in European mercury emissions or whether the load is still high because of continuing global emissions. In this study we use sediments from 12 lakes, located above the Arctic Circle in the Swedish mountains, to assess the past and recent mercury pollution situation, especially for the last 200 y. The mercury load increased clearly in sediment deposited from the late 19th or early 20th century to a peak between 1960 and 1990. This peak represents an enrichment of 1.4 to 4.2 times over background concentrations. This enrichment is comparable with enrichments in sediments from lower latitudes as well as other Arctic regions. Since the 1990s mercury concentration has declined in 8 of the 12 lakes, i.e., similar to emission trends in Europe.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Ambio},\n\tauthor = {Lindeberg, Carola and Bindler, Richard and Bigler, Christian and Rosén, Peter and Renberg, Ingemar},\n\tmonth = jul,\n\tyear = {2007},\n\tkeywords = {\\#nosource, Sweden, anthropogenic sources, atmospheric mercury, chironomids, climate-change, deposition, quantitative indicators, region, sediments, temperature},\n\tpages = {401--405},\n}\n\n\n\n\n\n Despite many years of research about mercury pollution, data concerning high-latitude regions of Europe are limited, particularly studies of long-term temporal trends. It is not clear whether the mercury load at high latitudes follows the recent decreasing trends in European mercury emissions or whether the load is still high because of continuing global emissions. In this study we use sediments from 12 lakes, located above the Arctic Circle in the Swedish mountains, to assess the past and recent mercury pollution situation, especially for the last 200 y. The mercury load increased clearly in sediment deposited from the late 19th or early 20th century to a peak between 1960 and 1990. This peak represents an enrichment of 1.4 to 4.2 times over background concentrations. This enrichment is comparable with enrichments in sediments from lower latitudes as well as other Arctic regions. Since the 1990s mercury concentration has declined in 8 of the 12 lakes, i.e., similar to emission trends in Europe.\n
\n\n\n\n \n\n \n \n \n \n \n \n Determinants of plant species richness in an alpine meadow.\n \n \n \n \n\n\n \n Olofsson, J; and Shams, H\n\n\n \n\n\n\n Journal of Ecology, 95(5): 916–925. September 2007.\n 00033\n\n\n\n
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\n\n\n@article{olofsson_determinants_2007,\n\ttitle = {Determinants of plant species richness in an alpine meadow},\n\tvolume = {95},\n\tissn = {1365-2745},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2007.01284.x/abstract},\n\tdoi = {10.1111/j.1365-2745.2007.01284.x},\n\tabstract = {* 1Nutrient availability, defoliation and soil disturbance are important factors that influence the richness of plant communities. However, few studies have examined the interactions between these factors, especially in harsh environments. We therefore examined the effects of fertilization, defoliation and soil disturbance on plant species richness in an alpine meadow in northern Sweden.\n* 2From 2002 to 2005, plots were fertilized, mowed and disturbed annually in a factorially designed experiment. Plant species richness, colonization and extinction were recorded in permanent subplots. Seedling densities and recruitment from seed of Potentilla crantzii were also estimated in order to examine the mechanisms whereby these treatments influence colonization by new species.\n* 3Species richness peaked in the absence of disturbance in unfertilized plots and with light disturbance in fertilized plots. Colonization by new vascular plant species, seed recruitment and seedling density were all increased by soil disturbance, suggesting that colonization was increased because conditions were more favourable for seed recruitment following the disturbance treatment. Extinction of species was highest in the mowed, intensively disturbed and unfertilized plots and lowest in the fertilized, lightly disturbed and unmowed plots.\n* 4Local extinction was negatively correlated with both moss and vascular plant biomass. Local colonization, seedling density and recruitment of P. crantzii were all strongly negatively correlated with the biomass of mosses. In contrast, the biomass of vascular plants was only weakly correlated with local colonization, seedling density and recruitment of P. crantzii.\n* 5This study suggest that the level of disturbance at which species richness peaks should move towards higher disturbance levels when productivity increases. However, lower extinction rates rather then higher colonization rates seem to be causing the increase in species richness following disturbance.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Ecology},\n\tauthor = {Olofsson, J and Shams, H},\n\tmonth = sep,\n\tyear = {2007},\n\tnote = {00033},\n\tkeywords = {\\#nosource, Potentilla crantzii, alpine, colonization, defoliation, disturbance, extinction, fertilization, recruitment, seed, species richness},\n\tpages = {916--925},\n}\n\n\n\n\n\n * 1Nutrient availability, defoliation and soil disturbance are important factors that influence the richness of plant communities. However, few studies have examined the interactions between these factors, especially in harsh environments. We therefore examined the effects of fertilization, defoliation and soil disturbance on plant species richness in an alpine meadow in northern Sweden. * 2From 2002 to 2005, plots were fertilized, mowed and disturbed annually in a factorially designed experiment. Plant species richness, colonization and extinction were recorded in permanent subplots. Seedling densities and recruitment from seed of Potentilla crantzii were also estimated in order to examine the mechanisms whereby these treatments influence colonization by new species. * 3Species richness peaked in the absence of disturbance in unfertilized plots and with light disturbance in fertilized plots. Colonization by new vascular plant species, seed recruitment and seedling density were all increased by soil disturbance, suggesting that colonization was increased because conditions were more favourable for seed recruitment following the disturbance treatment. Extinction of species was highest in the mowed, intensively disturbed and unfertilized plots and lowest in the fertilized, lightly disturbed and unmowed plots. * 4Local extinction was negatively correlated with both moss and vascular plant biomass. Local colonization, seedling density and recruitment of P. crantzii were all strongly negatively correlated with the biomass of mosses. In contrast, the biomass of vascular plants was only weakly correlated with local colonization, seedling density and recruitment of P. crantzii. * 5This study suggest that the level of disturbance at which species richness peaks should move towards higher disturbance levels when productivity increases. However, lower extinction rates rather then higher colonization rates seem to be causing the increase in species richness following disturbance.\n
\n\n\n\n \n\n \n \n \n \n \n Production of dissolved organic carbon and low-molecular weight organic acids in soil solution driven by recent tree photosynthate.\n \n \n \n\n\n \n Giesler, R.; Hogberg, M. N.; Strobel, B. W.; Richter, A.; Nordgren, A.; and Hogberg, P.\n\n\n \n\n\n\n Biogeochemistry, 84(1): 1–12. May 2007.\n 00064\n\n\n\n
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\n\n\n@article{giesler_production_2007,\n\ttitle = {Production of dissolved organic carbon and low-molecular weight organic acids in soil solution driven by recent tree photosynthate},\n\tvolume = {84},\n\tissn = {0168-2563},\n\tdoi = {10.1007/s10533-007-9069-3},\n\tabstract = {Dissolved organic carbon (DOC) is an important component in the terrestrial carbon cycle. Yet, the relative importance of different inputs of DOC to the soil solution remains uncertain. Here, we used a large-scale forest girdling experiment to examine how the supply of recent photosynthate to tree roots and their mycorrhizal fungi affects DOC, in particular low-molecular weight organic acids (LMWOA). We also studied effects of tree girdling on non-structural carbohydrates in microorganism, and examined the effects of freezing of soil and the presence of roots in the soil samples on soil solution DOC and LMWOA in this experiment. The concentration of DOC was reduced by 40\\%, while citrate was reduced by up to 90\\% in the soil solution by the girdling treatment. Other LMWOA such as oxalate, succinate, formate and propionate were unaffected by the girdling. We also found that girdling reduced the concentrations of trehalose (by 50\\%), a typical fungal sugar, and of monosaccharides (by 40\\%) in microorganisms in root-free soil. The effect of freezing on DOC concentrations was marked in samples from control plots, but insignificant in samples from girdled plots. Release of DOC from cell lysis after freezing was attributed equally to roots and to microorganisms. Our observations suggest a direct link from tree photosynthesis through roots and their mycorrhizal fungi to soil solution chemistry. This direct link should impact solute transport and speciation, mineral weathering and C dynamics in the soil compartment. Importantly, our finding of a substantial photosynthate driven production of DOC challenges the paradigm that DOC is mainly the result of decomposition of organic matter.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Biogeochemistry},\n\tauthor = {Giesler, Reiner and Hogberg, Mona N. and Strobel, Bjarne W. and Richter, Andreas and Nordgren, Anders and Hogberg, Peter},\n\tmonth = may,\n\tyear = {2007},\n\tnote = {00064},\n\tkeywords = {\\#nosource, DOC, Microbial biomass, Mycorrhizae, capillary-zone-electrophoresis, carbohydrates, carboxylic-acids, citrate, forest soil, forest soils, leaf-litter, litter decomposition, low-molecular weight organic acid, matter, microorganisms, rhizosphere, root respiration, soil solution, solution chemistry, tree photosynthesis, trehalose},\n\tpages = {1--12},\n}\n\n\n\n\n\n Dissolved organic carbon (DOC) is an important component in the terrestrial carbon cycle. Yet, the relative importance of different inputs of DOC to the soil solution remains uncertain. Here, we used a large-scale forest girdling experiment to examine how the supply of recent photosynthate to tree roots and their mycorrhizal fungi affects DOC, in particular low-molecular weight organic acids (LMWOA). We also studied effects of tree girdling on non-structural carbohydrates in microorganism, and examined the effects of freezing of soil and the presence of roots in the soil samples on soil solution DOC and LMWOA in this experiment. The concentration of DOC was reduced by 40%, while citrate was reduced by up to 90% in the soil solution by the girdling treatment. Other LMWOA such as oxalate, succinate, formate and propionate were unaffected by the girdling. We also found that girdling reduced the concentrations of trehalose (by 50%), a typical fungal sugar, and of monosaccharides (by 40%) in microorganisms in root-free soil. The effect of freezing on DOC concentrations was marked in samples from control plots, but insignificant in samples from girdled plots. Release of DOC from cell lysis after freezing was attributed equally to roots and to microorganisms. Our observations suggest a direct link from tree photosynthesis through roots and their mycorrhizal fungi to soil solution chemistry. This direct link should impact solute transport and speciation, mineral weathering and C dynamics in the soil compartment. Importantly, our finding of a substantial photosynthate driven production of DOC challenges the paradigm that DOC is mainly the result of decomposition of organic matter.\n
\n\n\n\n \n\n \n \n \n \n \n \n Composition and variations in the occurrence of dissolved free simple organic compounds of an unproductive lake ecosystem in northern Sweden.\n \n \n \n \n\n\n \n Jonsson, A.; Ström, L.; and Åberg, J.\n\n\n \n\n\n\n Biogeochemistry, 82(2): 153–163. February 2007.\n 00021\n\n\n\n
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\n\n\n@article{jonsson_composition_2007,\n\ttitle = {Composition and variations in the occurrence of dissolved free simple organic compounds of an unproductive lake ecosystem in northern {Sweden}},\n\tvolume = {82},\n\tissn = {0168-2563, 1573-515X},\n\turl = {http://link.springer.com/article/10.1007/s10533-006-9060-4},\n\tdoi = {10.1007/s10533-006-9060-4},\n\tabstract = {Low molecular weight organic carbon compounds are potentially important carbon and energy substrates to heterotrophic production in the aquatic environment. We studied the occurrence of dissolved free amino acids (AA), monosaccharides (CHO), and carboxylic acids (CA) in the subarctic Lake Diktar-Erik. The lake is unproductive with slightly humic water, and receives water via one major inlet stream draining a birch forest environment. The concentration of dissolved organic carbon (DOC) in the inlet stream was strongly correlated with the discharge. This relationship changed from season to season, indicating changes in the sources of the DOC entering the stream. AA and CHO each accounted for an average of less than 0.5\\% of the DOC. After high discharge events during the ice-free period, AA and CHO occurred in especially high concentrations. CA occurred in higher concentrations during the ice-free period, when it generally accounted for 20–30\\% of the DOC pool. The CA content relative to the total DOC pool was strongly inversely correlated with overall DOC concentration, and at low DOC levels the relative content of CA was high and vice versa. This followed a seasonal trend, with CA accounting for a smaller proportion of the DOC in winter and a larger part in spring/early summer. A conservative estimate suggested that the studied simple organic carbon compounds potentially could cover 30\\% of the bacterial gross production in the lake and therefore potentially also was an important source of CO2 that occur in supersaturated concentrations in the lake.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-08},\n\tjournal = {Biogeochemistry},\n\tauthor = {Jonsson, Anders and Ström, Lena and Åberg, Jan},\n\tmonth = feb,\n\tyear = {2007},\n\tnote = {00021},\n\tkeywords = {\\#nosource, Amino acids, Carbohydrates, Carboxylic acids, DOC, Subarctic lakes, respiration},\n\tpages = {153--163},\n}\n\n\n\n\n\n Low molecular weight organic carbon compounds are potentially important carbon and energy substrates to heterotrophic production in the aquatic environment. We studied the occurrence of dissolved free amino acids (AA), monosaccharides (CHO), and carboxylic acids (CA) in the subarctic Lake Diktar-Erik. The lake is unproductive with slightly humic water, and receives water via one major inlet stream draining a birch forest environment. The concentration of dissolved organic carbon (DOC) in the inlet stream was strongly correlated with the discharge. This relationship changed from season to season, indicating changes in the sources of the DOC entering the stream. AA and CHO each accounted for an average of less than 0.5% of the DOC. After high discharge events during the ice-free period, AA and CHO occurred in especially high concentrations. CA occurred in higher concentrations during the ice-free period, when it generally accounted for 20–30% of the DOC pool. The CA content relative to the total DOC pool was strongly inversely correlated with overall DOC concentration, and at low DOC levels the relative content of CA was high and vice versa. This followed a seasonal trend, with CA accounting for a smaller proportion of the DOC in winter and a larger part in spring/early summer. A conservative estimate suggested that the studied simple organic carbon compounds potentially could cover 30% of the bacterial gross production in the lake and therefore potentially also was an important source of CO2 that occur in supersaturated concentrations in the lake.\n
\n\n\n\n \n\n \n \n \n \n \n \n Wintering Black Terns Foraging Among Manta Rays in Coastal Guerrero, Mexico.\n \n \n \n \n\n\n \n Larson, K. W.; and Martinez Leyva, J. E.\n\n\n \n\n\n\n Waterbirds, 30(3): 448–449. 2007.\n 00001\n\n\n\n
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\n\n\n@article{larson_wintering_2007,\n\ttitle = {Wintering {Black} {Terns} {Foraging} {Among} {Manta} {Rays} in {Coastal} {Guerrero}, {Mexico}},\n\tvolume = {30},\n\turl = {c:/documents and settings/keith larson/my documents/pdf library/Waterbirds/Waterbirds Vol 30 No 3 p 448-449 2007.pdf},\n\tdoi = {10.1675/1524-4695(2007)030[0448:WBTFAM]2.0.CO;2},\n\tabstract = {Winter observations of Black Terns (Chlidonias niger) in Mexico are rare. On 19 January 2007, we observed over 3,000 Black Terns foraging among hundreds of breaching manta rays one kilometer offshore on the coast of Guerrero, Mexico.},\n\tnumber = {3},\n\tjournal = {Waterbirds},\n\tauthor = {Larson, Keith W. and Martinez Leyva, Jesus Eduardo},\n\tyear = {2007},\n\tnote = {00001},\n\tkeywords = {\\#nosource, Black Tern, Chlidonias niger, Guerrero, Mexico, WINTER, foraging, manta ray},\n\tpages = {448--449},\n}\n\n\n\n\n\n Winter observations of Black Terns (Chlidonias niger) in Mexico are rare. On 19 January 2007, we observed over 3,000 Black Terns foraging among hundreds of breaching manta rays one kilometer offshore on the coast of Guerrero, Mexico.\n
\n\n\n\n \n\n \n \n \n \n \n \n Are plant growth-form-based classifications useful in predicting northern ecosystem carbon cycling feedbacks to climate change?.\n \n \n \n \n\n\n \n Dorrepaal, E.\n\n\n \n\n\n\n Journal of Ecology, 95(6): 1167–1180. November 2007.\n \n\n\n\n
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\n\n\n@article{dorrepaal_are_2007,\n\ttitle = {Are plant growth-form-based classifications useful in predicting northern ecosystem carbon cycling feedbacks to climate change?},\n\tvolume = {95},\n\tissn = {1365-2745},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2007.01294.x/abstract},\n\tdoi = {10.1111/j.1365-2745.2007.01294.x},\n\tabstract = {* 1Plant species affect ecosystem carbon uptake via biomass production and carbon release via decomposition processes. Differences in their responses to climate change and effects on ecosystem carbon cycling processes may thus feedback to the atmospheric carbon balance and the climate at a global scale. Hierarchical species classifications based on plant growth forms are widely used in cold, northern biomes to generalize and predict these differences. This review investigates the usefulness of broad (vascular, non-vascular), intermediate (woody, non-woody) and narrow (evergreen shrubs, deciduous shrubs, graminoids, forbs) plant growth-form-based groups in these biomes for predicting plant responses to climate change and effects on the main processes of the full carbon cycle by looking at the similarity of species within growth-form groups and the consistency of differences among groups under changing environmental conditions.\n* 2Production responses to climate change differ between broad growth-form groups, but their opposite responses do not imply that the responses of non-vascular plants are consistently negative. Within vascular growth forms, production responses to climate change are not always similar among species under identical conditions, and average differences among narrow vascular growth forms are usually small. Moreover, differences in production responses among growth forms strongly depend upon the duration of the study, the region and the ecosystem type.\n* 3Species within narrow growth forms show a high similarity for a range of leaf litter chemistry variables and differences among narrow growth forms are often large and consistent. However, differences in leaf litter decomposability are large between broad growth-form groups, but small and environment-dependent among important narrow vascular growth forms. Litter feedback effects to plant production vary among narrow vascular growth forms, but the differences strongly depend on the study duration. Data on the climate dependence of growth-form differences regarding this aspect of the carbon cycle are currently lacking.\n* 4Synthesis: Overall, the usefulness of growth-form-based groups clearly differs between carbon cycling processes. Different aggregation levels are therefore needed for different processes. For most processes there is evidence that the differences among growth forms depend on environmental conditions, which hampers their use for generalizations and modelling. Future studies should therefore explicitly test for differences among growth-form groups and aim to unravel the dependence of growth-form differences on environmental conditions.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2017-02-09},\n\tjournal = {Journal of Ecology},\n\tauthor = {Dorrepaal, Ellen},\n\tmonth = nov,\n\tyear = {2007},\n\tkeywords = {\\#nosource, Litter decomposition, cold biomes, cryptogams, hierarchical classification, litter effects, peatlands, plant functional types, plant production, plant traits, tundra},\n\tpages = {1167--1180},\n}\n\n\n\n\n\n * 1Plant species affect ecosystem carbon uptake via biomass production and carbon release via decomposition processes. Differences in their responses to climate change and effects on ecosystem carbon cycling processes may thus feedback to the atmospheric carbon balance and the climate at a global scale. Hierarchical species classifications based on plant growth forms are widely used in cold, northern biomes to generalize and predict these differences. This review investigates the usefulness of broad (vascular, non-vascular), intermediate (woody, non-woody) and narrow (evergreen shrubs, deciduous shrubs, graminoids, forbs) plant growth-form-based groups in these biomes for predicting plant responses to climate change and effects on the main processes of the full carbon cycle by looking at the similarity of species within growth-form groups and the consistency of differences among groups under changing environmental conditions. * 2Production responses to climate change differ between broad growth-form groups, but their opposite responses do not imply that the responses of non-vascular plants are consistently negative. Within vascular growth forms, production responses to climate change are not always similar among species under identical conditions, and average differences among narrow vascular growth forms are usually small. Moreover, differences in production responses among growth forms strongly depend upon the duration of the study, the region and the ecosystem type. * 3Species within narrow growth forms show a high similarity for a range of leaf litter chemistry variables and differences among narrow growth forms are often large and consistent. However, differences in leaf litter decomposability are large between broad growth-form groups, but small and environment-dependent among important narrow vascular growth forms. Litter feedback effects to plant production vary among narrow vascular growth forms, but the differences strongly depend on the study duration. Data on the climate dependence of growth-form differences regarding this aspect of the carbon cycle are currently lacking. * 4Synthesis: Overall, the usefulness of growth-form-based groups clearly differs between carbon cycling processes. Different aggregation levels are therefore needed for different processes. For most processes there is evidence that the differences among growth forms depend on environmental conditions, which hampers their use for generalizations and modelling. Future studies should therefore explicitly test for differences among growth-form groups and aim to unravel the dependence of growth-form differences on environmental conditions.\n
\n\n\n\n \n\n \n \n \n \n \n \n Changing leaf litter feedbacks on plant production across contrasting sub-arctic peatland species and growth forms.\n \n \n \n \n\n\n \n Dorrepaal, E.; Cornelissen, J. H. C.; and Aerts, R.\n\n\n \n\n\n\n Oecologia, 151(2): 251–261. March 2007.\n 00044\n\n\n\n
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\n\n\n@article{dorrepaal_changing_2007,\n\ttitle = {Changing leaf litter feedbacks on plant production across contrasting sub-arctic peatland species and growth forms},\n\tvolume = {151},\n\tissn = {0029-8549, 1432-1939},\n\turl = {http://link.springer.com/article/10.1007/s00442-006-0580-3},\n\tdoi = {10.1007/s00442-006-0580-3},\n\tabstract = {Plant species and growth forms differ widely in litter chemistry, which affects decay and may have important consequences for plant growth via e.g. the release of nutrients and growth-inhibitory compounds. We investigated the overall short-term (9.5 months) and medium-term (21.5 months) feedback effects of leaf litter quality and quantity on plant production, and tested whether growth forms can be used to generalise differences among litter species. Leaf litter effects of 21 sub-arctic vascular peatland species on Poa alpina test plants changed clearly with time. Across all growth forms, litter initially reduced plant biomass compared with untreated plants, particularly litters with a high decomposition rate or low initial lignin/P ratio. In the second year, however, litter effects were neutral or positive, and related to initial litter N concentration (positive), C/N, polyphenol/N and polyphenol/P ratios (all negative), but not to decomposability. Differences in effect size among several litter species were large, while differences in response to increasing litter quantities were not significant or of similar magnitude to differences in response to three contrasting litter species. Growth forms did not differ in initial litter effects, but second-year plant production showed a trend (P {\\textless} 0.10) for differences in response to litters of different growth forms: evergreen shrubs {\\textless} graminoids or deciduous shrubs {\\textless} forbs. While long-persisting negative litter effects were predominant across all growth forms, our data indicate that even within nutrient-constrained ecosystems such as northern peatlands, vascular plant species, and possibly growth forms, differ in litter feedbacks to plant growth. Differences in the composition of undisturbed plant communities or species shifts induced by external disturbance, such as climate change, may therefore feedback strongly to plant biomass production and probably nutrient cycling rates in northern peatlands.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-08},\n\tjournal = {Oecologia},\n\tauthor = {Dorrepaal, Ellen and Cornelissen, Johannes H. C. and Aerts, Rien},\n\tmonth = mar,\n\tyear = {2007},\n\tnote = {00044},\n\tkeywords = {\\#nosource, Litter decomposition, Nitrogen, bartsia-alpina, climate-change, decomposition rates, dwarf shrub, functional types, high latitude, litter chemistry, mediated controls, phytometer, plant functional type, responses, tundra, vegetation},\n\tpages = {251--261},\n}\n\n\n\n\n\n Plant species and growth forms differ widely in litter chemistry, which affects decay and may have important consequences for plant growth via e.g. the release of nutrients and growth-inhibitory compounds. We investigated the overall short-term (9.5 months) and medium-term (21.5 months) feedback effects of leaf litter quality and quantity on plant production, and tested whether growth forms can be used to generalise differences among litter species. Leaf litter effects of 21 sub-arctic vascular peatland species on Poa alpina test plants changed clearly with time. Across all growth forms, litter initially reduced plant biomass compared with untreated plants, particularly litters with a high decomposition rate or low initial lignin/P ratio. In the second year, however, litter effects were neutral or positive, and related to initial litter N concentration (positive), C/N, polyphenol/N and polyphenol/P ratios (all negative), but not to decomposability. Differences in effect size among several litter species were large, while differences in response to increasing litter quantities were not significant or of similar magnitude to differences in response to three contrasting litter species. Growth forms did not differ in initial litter effects, but second-year plant production showed a trend (P \\textless 0.10) for differences in response to litters of different growth forms: evergreen shrubs \\textless graminoids or deciduous shrubs \\textless forbs. While long-persisting negative litter effects were predominant across all growth forms, our data indicate that even within nutrient-constrained ecosystems such as northern peatlands, vascular plant species, and possibly growth forms, differ in litter feedbacks to plant growth. Differences in the composition of undisturbed plant communities or species shifts induced by external disturbance, such as climate change, may therefore feedback strongly to plant biomass production and probably nutrient cycling rates in northern peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Respiration of allochthonous organic carbon in unproductive forest lakes determined by the Keeling plot method.\n \n \n \n \n\n\n \n Karlsson, J.; Jansson, M.; and Jonsson, A.\n\n\n \n\n\n\n Limnology and Oceanography, 52(2): 603–608. March 2007.\n 00090\n\n\n\n
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\n\n\n@article{karlsson_respiration_2007,\n\ttitle = {Respiration of allochthonous organic carbon in unproductive forest lakes determined by the {Keeling} plot method},\n\tvolume = {52},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com/doi/10.4319/lo.2007.52.2.0603/abstract},\n\tdoi = {10.4319/lo.2007.52.2.0603},\n\tabstract = {We carried out short-term (2 d) experiments in nine unproductive lakes in northern Sweden in order to investigate organic carbon sources supporting lake water respiration. Surface water was incubated in gas-tight bottles in the dark, and the concentration and isotopic composition (δ13C) of dissolved inorganic carbon (DIC) were measured at the start and end of the incubations. Keeling plot analyses revealed that the δ13C of the respired carbon was between -28.4\\% and -30.6\\% in the lakes and that the respired carbon was mainly of allochthonous organic carbon (AlloOC) origin. The respiration of AlloOC corresponded well with metabolic imbalances indicated by negative net ecosystem production (NEP) values in the lake waters. Keeling plot analysis of DIC accumulating in the hypolimnion of two lakes during summer stratification showed δ13C values of around -26.6\\% for excess DIC, implying that the accumulation of DIC was mainly derived from respiration of AlloOC. Our data provide direct evidence that net heterotrophy of these lakes is caused by input and respiration of AlloOC. We conclude that the Keeling plot method is a powerful technique that enables characterization and quantification of the organic carbon sources contributing to respiration in aquatic systems.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-09},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Karlsson, Jan and Jansson, Mats and Jonsson, Anders},\n\tmonth = mar,\n\tyear = {2007},\n\tnote = {00090},\n\tkeywords = {\\#nosource, clear-water lakes, dioxide, dissolved inorganic carbon, food webs, fractionation, humic lakes, metabolism, northern sweden, stable-isotope analysis, zooplankton},\n\tpages = {603--608},\n}\n\n\n\n\n\n We carried out short-term (2 d) experiments in nine unproductive lakes in northern Sweden in order to investigate organic carbon sources supporting lake water respiration. Surface water was incubated in gas-tight bottles in the dark, and the concentration and isotopic composition (δ13C) of dissolved inorganic carbon (DIC) were measured at the start and end of the incubations. Keeling plot analyses revealed that the δ13C of the respired carbon was between -28.4% and -30.6% in the lakes and that the respired carbon was mainly of allochthonous organic carbon (AlloOC) origin. The respiration of AlloOC corresponded well with metabolic imbalances indicated by negative net ecosystem production (NEP) values in the lake waters. Keeling plot analysis of DIC accumulating in the hypolimnion of two lakes during summer stratification showed δ13C values of around -26.6% for excess DIC, implying that the accumulation of DIC was mainly derived from respiration of AlloOC. Our data provide direct evidence that net heterotrophy of these lakes is caused by input and respiration of AlloOC. We conclude that the Keeling plot method is a powerful technique that enables characterization and quantification of the organic carbon sources contributing to respiration in aquatic systems.\n
\n\n\n\n \n\n \n \n \n \n \n Variations in pCO(2) during summer in the surface water of an unproductive lake in northern Sweden.\n \n \n \n\n\n \n Jonsson, A.; Aberg, J.; and Jansson, M.\n\n\n \n\n\n\n Tellus Series B-Chemical and Physical Meteorology, 59(5): 797–803. November 2007.\n \n\n\n\n
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\n\n\n@article{jonsson_variations_2007,\n\ttitle = {Variations in {pCO}(2) during summer in the surface water of an unproductive lake in northern {Sweden}},\n\tvolume = {59},\n\tissn = {0280-6509},\n\tdoi = {10.1111/j.1600-0889.2007.00307.x},\n\tabstract = {Unproductive lakes are generally supersaturated with carbon dioxide (CO2) and emit CO2 to the atmosphere continuously during ice-free periods. However, temporal variation of the partial pressure Of CO2 (PCO2) and thus Of CO2 evasion to atmosphere is poorly documented. We therefore carried out temporally high-resolution (every 6 h) measurements of the PCO2 using an automated logger system in the surface water of a subarctic, unproductive, lake in the birch forest belt. The study period was June-September 2004. We found that the PCO2 showed large seasonal variation, but low daily variation. The seasonal variation was likely mainly caused by variations in input and mineralization of allocluthonous organic matter. Stratification depth probably also influenced PCO2 of the surface water by controlling the volume in which mineralization of dissolved organic carbon (DOC) occurred. In lakes, with large variations in PCO2, as in our study lake a high (weekly) sampling intensity is recommended for obtaining accurate estimates of the evasion Of CO2.},\n\tlanguage = {English},\n\tnumber = {5},\n\tjournal = {Tellus Series B-Chemical and Physical Meteorology},\n\tauthor = {Jonsson, A. and Aberg, J. and Jansson, M.},\n\tmonth = nov,\n\tyear = {2007},\n\tkeywords = {\\#nosource, CO2, allochthonous organic-carbon, bacterioplankton production, boreal, clearwater, dioxide supersaturation, dissolved inorganic carbon, humic lakes, respiration, wisconsin},\n\tpages = {797--803},\n}\n\n\n\n\n\n Unproductive lakes are generally supersaturated with carbon dioxide (CO2) and emit CO2 to the atmosphere continuously during ice-free periods. However, temporal variation of the partial pressure Of CO2 (PCO2) and thus Of CO2 evasion to atmosphere is poorly documented. We therefore carried out temporally high-resolution (every 6 h) measurements of the PCO2 using an automated logger system in the surface water of a subarctic, unproductive, lake in the birch forest belt. The study period was June-September 2004. We found that the PCO2 showed large seasonal variation, but low daily variation. The seasonal variation was likely mainly caused by variations in input and mineralization of allocluthonous organic matter. Stratification depth probably also influenced PCO2 of the surface water by controlling the volume in which mineralization of dissolved organic carbon (DOC) occurred. In lakes, with large variations in PCO2, as in our study lake a high (weekly) sampling intensity is recommended for obtaining accurate estimates of the evasion Of CO2.\n
\n\n\n\n \n\n \n \n \n \n \n Linkages between N turnover and plant community structure in a tundra landscape.\n \n \n \n\n\n \n Bjork, R. G.; Klemedtsson, L.; Molau, U.; Harndorf, J.; Odman, A.; and Giesler, R.\n\n\n \n\n\n\n Plant and Soil, 294(1-2): 247–261. May 2007.\n \n\n\n\n
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\n\n\n@article{bjork_linkages_2007,\n\ttitle = {Linkages between {N} turnover and plant community structure in a tundra landscape},\n\tvolume = {294},\n\tissn = {0032-079X},\n\tdoi = {10.1007/s11104-007-9250-4},\n\tabstract = {The spatial distribution of organic soil nitrogen (N) in alpine tundra was studied along a natural environmental gradient, covering five plant communities, at the Latnjajaure Field Station, northern Swedish Lapland. The five communities (mesic meadow, meadow snowbed, dry heath, mesic heath, and heath snowbed) are the dominant types in this region and are differentiated by soil pH. Net N mineralization, net ammonification, and net nitrification were measured using 40-day laboratory incubations based on extractable NH4+ and NO3-. Nitrification enzyme activity (NEA), denitrification enzyme activity (DEA), amino acid concentrations, and microbial respiration were measured for soils from each plant community. The results show that net N mineralization rates were more than three times higher in the meadow ecosystems (mesic meadow 0.7 mu g N g(-1) OM day(-1) and meadow snowbed 0.6 mu g N g(-1) OM day(-1)) than the heath ecosystems (dry heath 0.2 mu g N g(-1) OM day(-1), mesic heath 0.1 mu g N g(-1) OM day(-1) and heath snowbed 0.2 mu g N g(-1) OM day(-1)). The net N mineralization rates were negatively correlated to organic soil C/N ratio (r = -0.652, P {\\textless} 0.001) and positively correlated to soil pH (r = 0.701, P {\\textless} 0.001). Net nitrification, inorganic N concentrations, and NEA rates also differed between plant communities; the values for the mesic meadow were at least four times higher than the other plant communities, and the snowbeds formed an intermediate group. Moreover, the results show a different pattern of distribution for individual amino acids across the plant communities, with snowbeds tending to have the highest amino acid N concentrations. The differences between plant communities along this natural gradient also illustrate variations between the dominant mycorrhizal associations in facilitating N capture by the characteristic functional groups of plants.},\n\tlanguage = {English},\n\tnumber = {1-2},\n\tjournal = {Plant and Soil},\n\tauthor = {Bjork, Robert G. and Klemedtsson, Leif and Molau, Ulf and Harndorf, Jan and Odman, Anja and Giesler, Reiner},\n\tmonth = may,\n\tyear = {2007},\n\tkeywords = {\\#nosource, Amino acids, Ecosystems, Mineralization, arctic tundra, availability, boreal forests, environmental gradient, humus layer, iron accumulation, microbially available nitrogen, nitrification, nitrogen deposition, soil respiration, spatial variation, vegetation},\n\tpages = {247--261},\n}\n\n\n\n\n\n The spatial distribution of organic soil nitrogen (N) in alpine tundra was studied along a natural environmental gradient, covering five plant communities, at the Latnjajaure Field Station, northern Swedish Lapland. The five communities (mesic meadow, meadow snowbed, dry heath, mesic heath, and heath snowbed) are the dominant types in this region and are differentiated by soil pH. Net N mineralization, net ammonification, and net nitrification were measured using 40-day laboratory incubations based on extractable NH4+ and NO3-. Nitrification enzyme activity (NEA), denitrification enzyme activity (DEA), amino acid concentrations, and microbial respiration were measured for soils from each plant community. The results show that net N mineralization rates were more than three times higher in the meadow ecosystems (mesic meadow 0.7 mu g N g(-1) OM day(-1) and meadow snowbed 0.6 mu g N g(-1) OM day(-1)) than the heath ecosystems (dry heath 0.2 mu g N g(-1) OM day(-1), mesic heath 0.1 mu g N g(-1) OM day(-1) and heath snowbed 0.2 mu g N g(-1) OM day(-1)). The net N mineralization rates were negatively correlated to organic soil C/N ratio (r = -0.652, P \\textless 0.001) and positively correlated to soil pH (r = 0.701, P \\textless 0.001). Net nitrification, inorganic N concentrations, and NEA rates also differed between plant communities; the values for the mesic meadow were at least four times higher than the other plant communities, and the snowbeds formed an intermediate group. Moreover, the results show a different pattern of distribution for individual amino acids across the plant communities, with snowbeds tending to have the highest amino acid N concentrations. The differences between plant communities along this natural gradient also illustrate variations between the dominant mycorrhizal associations in facilitating N capture by the characteristic functional groups of plants.\n
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\n \n \n\n \n \n \n \n \n \n Tree Rings as Sensitive Proxies of Past Climate Change.\n \n \n \n \n\n\n \n Grudd, H.\n\n\n \n\n\n\n Ph.D. Thesis, Stockholm University, Stockholm, Sweden, 2006.\n Publisher: Institutionen för naturgeografi och kvartärgeologi\n\n\n\n
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\n\n\n@phdthesis{grudd_tree_2006,\n\taddress = {Stockholm, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Tree {Rings} as {Sensitive} {Proxies} of {Past} {Climate} {Change}},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1034},\n\tabstract = {In the boreal forests of the Northern Hemisphere, time series of tree-ring width (TRW) and maximum density in the latewood (MXD) are highly correlated to local instrumental summer-temperature data and are thus widely used as proxies in high-resolution climate reconstructions. Hence, much of our present knowledge about climatic variability in the last millennium is based on tree-rings. However, many tree-ring records have a lack of data in the most recent decades, which severely hampers our ability to place the recent temperature increase in a longer-timescale perspective of natural variability.\n\nThe main objective of this thesis is to update and extend the Torneträsk TRW and MXD records in northern Sweden. Local instrumental climate-data is used to calibrate the new tree-ring records. The results show that TRW is mainly forced by temperature in the early growing season (June/July) while MXD has a wider response window (June – August) and has a higher correlation to temperature. Two reconstructions of summer temperature are made for (i) the last 7,400 years based on TRW, and (ii) the last 1,500 years based on a combination of TRW and MXD. The reconstructions show natural variability on timescales from years to several centuries. The 20th century does not stand out as a notably warm period in the long timescale perspective. A medieval period from AD 900 – 1100 is markedly warmer than the 20th century.\n\nThe environmental impact from a large explosive volcanic eruption in 1628/1627 BC is analysed in the tree rings of 14C-dated bog pines in south-central Sweden and in absolutely-dated subfossil pines from Torneträsk. The results show evidence of an impact in the southern site at approximately this time but no detectable impact in the North.\n\nSubfossil trees of Fitzroya cupressoides in southern Chile were 14C-dated to approx. 50,000 years BP and amalgamated into a 1,229-year TRW chronology. This tree-ring record is the oldest in the world. The variability in this Last-glacial chronology is similar to the variability in present-day living trees of the same species. These results suggest that the growth–forcing mechanisms 50,000 years ago were similar to those at present.},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Stockholm University},\n\tauthor = {Grudd, Håkan},\n\tcollaborator = {Karlén, Wibjörn},\n\tyear = {2006},\n\tnote = {Publisher: Institutionen för naturgeografi och kvartärgeologi},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n}\n\n\n\n\n\n In the boreal forests of the Northern Hemisphere, time series of tree-ring width (TRW) and maximum density in the latewood (MXD) are highly correlated to local instrumental summer-temperature data and are thus widely used as proxies in high-resolution climate reconstructions. Hence, much of our present knowledge about climatic variability in the last millennium is based on tree-rings. However, many tree-ring records have a lack of data in the most recent decades, which severely hampers our ability to place the recent temperature increase in a longer-timescale perspective of natural variability. The main objective of this thesis is to update and extend the Torneträsk TRW and MXD records in northern Sweden. Local instrumental climate-data is used to calibrate the new tree-ring records. The results show that TRW is mainly forced by temperature in the early growing season (June/July) while MXD has a wider response window (June – August) and has a higher correlation to temperature. Two reconstructions of summer temperature are made for (i) the last 7,400 years based on TRW, and (ii) the last 1,500 years based on a combination of TRW and MXD. The reconstructions show natural variability on timescales from years to several centuries. The 20th century does not stand out as a notably warm period in the long timescale perspective. A medieval period from AD 900 – 1100 is markedly warmer than the 20th century. The environmental impact from a large explosive volcanic eruption in 1628/1627 BC is analysed in the tree rings of 14C-dated bog pines in south-central Sweden and in absolutely-dated subfossil pines from Torneträsk. The results show evidence of an impact in the southern site at approximately this time but no detectable impact in the North. Subfossil trees of Fitzroya cupressoides in southern Chile were 14C-dated to approx. 50,000 years BP and amalgamated into a 1,229-year TRW chronology. This tree-ring record is the oldest in the world. The variability in this Last-glacial chronology is similar to the variability in present-day living trees of the same species. These results suggest that the growth–forcing mechanisms 50,000 years ago were similar to those at present.\n
\n\n\n\n \n\n \n \n \n \n \n Holocene environmental history of Lake Vuolep Njakajaure (Abisko National Park, Northern Sweden) reconstructed using biological proxy indicators.\n \n \n \n\n\n \n Bigler, C.; Barnekow, L.; Heinrichs, M. L.; and Hall, R. I.\n\n\n \n\n\n\n Vegetation History and Archaeobotany, 15(4): 309–320. September 2006.\n \n\n\n\n
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\n\n\n@article{bigler_holocene_2006,\n\ttitle = {Holocene environmental history of {Lake} {Vuolep} {Njakajaure} ({Abisko} {National} {Park}, {Northern} {Sweden}) reconstructed using biological proxy indicators},\n\tvolume = {15},\n\tissn = {0939-6314},\n\tdoi = {10.1007/s00334-006-0054-x},\n\tabstract = {Holocene environmental and climatic changes are reconstructed using analyses of biological proxies in lake sediments from Vuolep Njakajaure, a lake located near the altitudinal treeline in northern Sweden (68 degrees 20' N, 18 degrees 47' E). We analysed biological proxy indicators from both aquatic and terrestrial ecosystems, including diatoms, pollen and chironomid head capsules, in order to reconstruct regional Holocene climate and the development of the lake and its catchment. During the early Holocene and after 2500 cal B.P., Fragilaria taxa dominated the diatom assemblages, whereas planktonic Cyclotella taxa prevailed during the major part of the Holocene (7800-2300 cal B.P.), indicating the importance of the pelagic habitat for diatom assemblage composition. The planktonic diatoms appeared at the same time as Alnus became established in the catchment, probably altering nutrient availability and catchment stability. The pollen record is dominated by mountain birch (Betula pubescens ssp. tortuosa) pollen throughout the Holocene, but high percentage abundances of Scots pine (Pinus sylvestris) pollen suggest the presence of a mixed pine-birch forest during the mid-Holocene (6800-2300 cal B.P.). Head capsules of Tanytarsini and Psectrocladius dominated the chironomid assemblage composition throughout the Holocene, in combination with Corynocera ambigua after 2300 cal B.P. A quantitative, diatom-based reconstruction of mean July air temperature indicated a relatively cold temperature during the early Holocene (9000-8000 cal B.P.) and after ca. 2300 cal B.P., whereas the mid-Holocene period is characterised by stable and warm temperatures. The overall patterns of Holocene climate and environmental conditions are similarly described by all biological proxy-indicators, suggesting relatively warm conditions during the mid-Holocene (ca. 7800-2300 cal B.P.), with a subsequent colder climate after 2300 cal B.P. However, the onset and magnitude of the inferred changes differ slightly among the proxies, illustrating different responses to lake development phases, land-uplift, and climate forcing (e.g., insolation patterns) during the Holocene in northern Sweden.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Vegetation History and Archaeobotany},\n\tauthor = {Bigler, Christian and Barnekow, Lena and Heinrichs, Markus L. and Hall, Roland I.},\n\tmonth = sep,\n\tyear = {2006},\n\tkeywords = {\\#nosource, Holocene, Pollen, air temperatures, chironomids, climatic-change, diatoms, ice-cover, krakenes lake, quantitative indicators, quantitative temperature reconstruction, subarctic Sweden, swedish lapland, swiss alps, tornetrask area, western norway},\n\tpages = {309--320},\n}\n\n\n\n\n\n Holocene environmental and climatic changes are reconstructed using analyses of biological proxies in lake sediments from Vuolep Njakajaure, a lake located near the altitudinal treeline in northern Sweden (68 degrees 20' N, 18 degrees 47' E). We analysed biological proxy indicators from both aquatic and terrestrial ecosystems, including diatoms, pollen and chironomid head capsules, in order to reconstruct regional Holocene climate and the development of the lake and its catchment. During the early Holocene and after 2500 cal B.P., Fragilaria taxa dominated the diatom assemblages, whereas planktonic Cyclotella taxa prevailed during the major part of the Holocene (7800-2300 cal B.P.), indicating the importance of the pelagic habitat for diatom assemblage composition. The planktonic diatoms appeared at the same time as Alnus became established in the catchment, probably altering nutrient availability and catchment stability. The pollen record is dominated by mountain birch (Betula pubescens ssp. tortuosa) pollen throughout the Holocene, but high percentage abundances of Scots pine (Pinus sylvestris) pollen suggest the presence of a mixed pine-birch forest during the mid-Holocene (6800-2300 cal B.P.). Head capsules of Tanytarsini and Psectrocladius dominated the chironomid assemblage composition throughout the Holocene, in combination with Corynocera ambigua after 2300 cal B.P. A quantitative, diatom-based reconstruction of mean July air temperature indicated a relatively cold temperature during the early Holocene (9000-8000 cal B.P.) and after ca. 2300 cal B.P., whereas the mid-Holocene period is characterised by stable and warm temperatures. The overall patterns of Holocene climate and environmental conditions are similarly described by all biological proxy-indicators, suggesting relatively warm conditions during the mid-Holocene (ca. 7800-2300 cal B.P.), with a subsequent colder climate after 2300 cal B.P. However, the onset and magnitude of the inferred changes differ slightly among the proxies, illustrating different responses to lake development phases, land-uplift, and climate forcing (e.g., insolation patterns) during the Holocene in northern Sweden.\n
\n\n\n\n \n\n \n \n \n \n \n \n Bacterioplankton Growth and Nutrient Use Efficiencies Under Variable Organic Carbon and Inorganic Phosphorus Ratios.\n \n \n \n \n\n\n \n Jansson, M.; Bergström, A.; Lymer, D.; Vrede, K.; and Karlsson, J.\n\n\n \n\n\n\n Microbial Ecology, 52(2): 358–364. August 2006.\n \n\n\n\n
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\n\n\n@article{jansson_bacterioplankton_2006,\n\ttitle = {Bacterioplankton {Growth} and {Nutrient} {Use} {Efficiencies} {Under} {Variable} {Organic} {Carbon} and {Inorganic} {Phosphorus} {Ratios}},\n\tvolume = {52},\n\tissn = {0095-3628, 1432-184X},\n\turl = {http://link.springer.com/article/10.1007/s00248-006-9013-4},\n\tdoi = {10.1007/s00248-006-9013-4},\n\tabstract = {We carried out enclosure experiments in an unproductive lake in northern Sweden and studied the effects of enrichment with different dissolved organic carbon (glucose)/inorganic phosphorous (DOC/Pi) ratios on bacterioplankton production (BP), growth efficiency (BGE), nutrient use efficiency (BNUE), growth rate, and specific respiration. We found considerable variation in BP, BGE, and BNUE along the tested DOC/Pi gradient. BGE varied between 0.87 and 0.24, with the highest values at low DOC/Pi ratios. BNUE varied between 40 and 9 g C g P−1, with high values at high DOC/Pi ratios. More DOC was thus allocated to growth when bacteria tended to be C-limited, and to respiration when bacteria were P-limited. Specific respiration was positively correlated with bacterial growth rate throughout the gradient. It is therefore possible that respiration was used to support growth in P-limited bacteria. The results indicated that BP can be limited by Pi when BNUE is at its maximum, by organic C when BGE is at its maximum, and by dual organic C and Pi limitation when BNUE and BGE have suboptimal values.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-06},\n\tjournal = {Microbial Ecology},\n\tauthor = {Jansson, Mats and Bergström, Ann-Kristin and Lymer, David and Vrede, Katarina and Karlsson, Jan},\n\tmonth = aug,\n\tyear = {2006},\n\tkeywords = {\\#nosource, Nitrogen, bacterial-growth, balance, clearwater, community, lakes, limitation, matter, metabolism, stoichiometry},\n\tpages = {358--364},\n}\n\n\n\n\n\n We carried out enclosure experiments in an unproductive lake in northern Sweden and studied the effects of enrichment with different dissolved organic carbon (glucose)/inorganic phosphorous (DOC/Pi) ratios on bacterioplankton production (BP), growth efficiency (BGE), nutrient use efficiency (BNUE), growth rate, and specific respiration. We found considerable variation in BP, BGE, and BNUE along the tested DOC/Pi gradient. BGE varied between 0.87 and 0.24, with the highest values at low DOC/Pi ratios. BNUE varied between 40 and 9 g C g P−1, with high values at high DOC/Pi ratios. More DOC was thus allocated to growth when bacteria tended to be C-limited, and to respiration when bacteria were P-limited. Specific respiration was positively correlated with bacterial growth rate throughout the gradient. It is therefore possible that respiration was used to support growth in P-limited bacteria. The results indicated that BP can be limited by Pi when BNUE is at its maximum, by organic C when BGE is at its maximum, and by dual organic C and Pi limitation when BNUE and BGE have suboptimal values.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant performance in a warmer world: general responses of plants from cold, northern biomes and the importance of winter and spring events.\n \n \n \n \n\n\n \n Aerts, R.; Cornelissen, J. H. C.; and Dorrepaal, E.\n\n\n \n\n\n\n In Rozema, J.; Aerts, R.; and Cornelissen, H., editor(s), Plants and Climate Change, of Tasks for vegetation science, pages 65–78. Springer Netherlands, Dordrecht, 2006.\n 00207 \n\n\n\n
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\n\n\n@incollection{aerts_plant_2006,\n\taddress = {Dordrecht},\n\tseries = {Tasks for vegetation science},\n\ttitle = {Plant performance in a warmer world: general responses of plants from cold, northern biomes and the importance of winter and spring events},\n\tisbn = {978-1-4020-4443-4},\n\tshorttitle = {Plant performance in a warmer world},\n\turl = {https://doi.org/10.1007/978-1-4020-4443-4_5},\n\tabstract = {During the past three decades the Earth has warmed with a rate unprecedented during the past 1000 years. There is already ample evidence that this fast climate warming has affected a broad range of organisms, including plants. Plants from high-latitude and high-altitude sites (‘cold biomes’) are especially sensitive to climate warming. In this paper we (1) review the response in the phenology of plants, changes in their range and distribution, soil nutrient availability, and the effects on the structure and dynamics of plant communities for cold, northern biomes; and (2) we show, by using data from an ongoing snow and temperature manipulation experiment in northern Sweden, that also winter and spring events have a profound influence on plant performance. Both long-term phenological data sets, experimental warming studies (performed in summer or year-round), natural gradient studies and satellite images show that key phenological events are responsive to temperature increases and that recent climate warming does indeed lead to changes in plant phenology. However, data from a warming and snow manipulation study that we are conducting in northern Sweden show that plants respond differently to the various climatic scenarios that we had imposed on these species and that especially winter and spring events have a profound impact. This indicates that it is necessary to include several scenarios of both summer and winter climate change in experimental climate change studies, and that we need detailed projections of future climate at a regional scale to be able to assess their impacts on natural ecosystems. There is also ample evidence that the range shift of herbs and shrubs to more northern regions is for the vast majority of species mainly caused by changes in the climate. This is in line with the observed ‘up-greening’ of northern tundra sites. These rapid northern shifts in distribution of plants as a result of climate warming may have substantial consequences for the structure and dynamics of high-latitude ecosystems. An analysis of warming studies at 9 tundra sites shows that heating during at least 3 years increased net N-mineralization from 0.32±0.31 (SE) g N m−2 yr−1 in the controls to 0.53±0.31 (SE) g N m−2 yr−1 in the heated plots (p{\\textless}0.05), an increase of about 70\\%. Thus, warming leads to higher N availability in high-latitude northern tundra sites, but the variability is substantial. Higher nutrient availability affects in turn the species composition of high-latitude sites, which has important consequences for the carbon and water balance of these systems.},\n\tlanguage = {en},\n\turldate = {2018-09-17},\n\tbooktitle = {Plants and {Climate} {Change}},\n\tpublisher = {Springer Netherlands},\n\tauthor = {Aerts, R. and Cornelissen, J. H. C. and Dorrepaal, E.},\n\teditor = {Rozema, Jelte and Aerts, Rien and Cornelissen, Hans},\n\tyear = {2006},\n\tdoi = {10.1007/978-1-4020-4443-4_5},\n\tnote = {00207 },\n\tkeywords = {\\#nosource, Climate warming, Nutrient availability, Peatlands, Phenology, Sphagnum, Tundra},\n\tpages = {65--78},\n}\n\n\n\n\n\n During the past three decades the Earth has warmed with a rate unprecedented during the past 1000 years. There is already ample evidence that this fast climate warming has affected a broad range of organisms, including plants. Plants from high-latitude and high-altitude sites (‘cold biomes’) are especially sensitive to climate warming. In this paper we (1) review the response in the phenology of plants, changes in their range and distribution, soil nutrient availability, and the effects on the structure and dynamics of plant communities for cold, northern biomes; and (2) we show, by using data from an ongoing snow and temperature manipulation experiment in northern Sweden, that also winter and spring events have a profound influence on plant performance. Both long-term phenological data sets, experimental warming studies (performed in summer or year-round), natural gradient studies and satellite images show that key phenological events are responsive to temperature increases and that recent climate warming does indeed lead to changes in plant phenology. However, data from a warming and snow manipulation study that we are conducting in northern Sweden show that plants respond differently to the various climatic scenarios that we had imposed on these species and that especially winter and spring events have a profound impact. This indicates that it is necessary to include several scenarios of both summer and winter climate change in experimental climate change studies, and that we need detailed projections of future climate at a regional scale to be able to assess their impacts on natural ecosystems. There is also ample evidence that the range shift of herbs and shrubs to more northern regions is for the vast majority of species mainly caused by changes in the climate. This is in line with the observed ‘up-greening’ of northern tundra sites. These rapid northern shifts in distribution of plants as a result of climate warming may have substantial consequences for the structure and dynamics of high-latitude ecosystems. An analysis of warming studies at 9 tundra sites shows that heating during at least 3 years increased net N-mineralization from 0.32±0.31 (SE) g N m−2 yr−1 in the controls to 0.53±0.31 (SE) g N m−2 yr−1 in the heated plots (p\\textless0.05), an increase of about 70%. Thus, warming leads to higher N availability in high-latitude northern tundra sites, but the variability is substantial. Higher nutrient availability affects in turn the species composition of high-latitude sites, which has important consequences for the carbon and water balance of these systems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Nutrient dynamics of reindeer forage species along snowmelt gradients at different ecological scales.\n \n \n \n \n\n\n \n Mårell, A.; Hofgaard, A.; and Danell, K.\n\n\n \n\n\n\n Basic and Applied Ecology, 7(1): 13–30. January 2006.\n 00057\n\n\n\n
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\n\n\n@article{marell_nutrient_2006,\n\ttitle = {Nutrient dynamics of reindeer forage species along snowmelt gradients at different ecological scales},\n\tvolume = {7},\n\tissn = {1439-1791},\n\turl = {http://www.sciencedirect.com/science/article/pii/S1439179105000514},\n\tdoi = {10.1016/j.baae.2005.04.005},\n\tabstract = {Summary\nGrowing season nutrient dynamics of four reindeer forage species (Betula nana, Eriophorum angustifolium, Rumex acetosa and Vaccinium myrtillus) were studied in a mountainous sub-arctic landscape in N Sweden. Changes in nitrogen (N), phosphorus (P) and fibre (ADF) concentrations in leaves and shoots were analysed (from a reindeer foraging perspective) along four ecological gradients significant to regional and local snowmelt regimes: season, oceanicity, altitude, and snow-patch retreat. N and P concentrations showed marked seasonal variations with peaks occurring from the middle of June to the end of July depending on species and snowmelt progression. The seasonal pattern for ADF concentrations, as well as differences between snowmelt regimes, were less consistent and showed large differences between species. N concentrations increased along snowmelt gradients at small (within snow-patches) and medium (along altitude gradients) spatial scales. Furthermore, variations in N concentrations were temporally and spatially scale-dependent, which underlines the importance of scale for understanding plant nutrient dynamics in sub-arctic and alpine systems, as well for plant–animal interactions. The greatest temporal and spatial differences in nutrient quality were observed early in the season, i.e., at the time of highest nutrient requirements for reindeer. Climate-induced changes of the start and the progress of the growing season may result in significant consequences to the development of calves and subsequently to the population demography of reindeer, mediated through spatial and temporal changes in the distribution of high quality food. These results provide basic knowledge for reindeer management in the light of the ongoing global warming.\nZusammenfassung\nDie Nährstoffdynamiken in der Wachstumsperiode wurden bei vier Arten von Rentierfutterpflanzen (Betula nana, Eriophorum angustifolium, Rumex acetosa, Vaccinium myrtillus) in einer bergigen subarktischen Landschaft N-Schwedens untersucht. Die Veränderungen der Konzentrationen von Stickstoff (N), Phosphor (P) und Fasern (ADF) in den Blättern und Trieben wurden entlang von vier ökologischen Gradienten analysiert, die für regionale und lokale Schneeschmelzeregimes bezeichnend sind: Jahreszeit, Ozeanität, Höhe und Schneefleckenrefugien. Die N- und P-Konzentrationen zeigten deutliche saisonale Variationen mit Spitzen, die zwischen Mitte Juni und Ende Juli auftraten, abhängig von Art und Fortschritt der Schneeschmelze. Das saisonale Muster der ADF-Konzentrationen sowie die Unterschiede zwischen den Schneeschmelzeregimes waren weniger konsistent und zeigten große Unterschiede zwischen den Arten. Die N-Konzentrationen stiegen entlang von Schneeschmelzegradienten auf kleinen (innerhalb von Schneeflecken) und mittleren (entlang von Höhengradienten) räumlichen Skalen an. Darüber hinaus waren die Variationen in den N-Konzentrationen zeitlich und räumlich skalenabhängig. Dies unterstreicht die Wichtigkeit der Skala für das Verständnis der Dynamiken von Pflanzennährstoffen in subarktischen und alpinen Systemen, sowie der Pflanze-Tier-Interaktionen. Die größten zeitlichen und räumlichen Unterschiede in der Nährstoffqualität wurden früh in der Saison beobachtet, d. h. zur Zeit des höchsten Nährstoffbedarfs der Rentiere. Klimainduzierte Veränderungen des Beginns und Verlaufs der Wachstumssaison können signifikante Konsequenzen für die Entwicklung von Kälbern und infolgedessen für die Populationsdemografie der Rentiere zum Ergebnis haben, vermittelt durch räumliche und zeitliche Veränderungen in der Verbreitung von Futter hoher Qualität. Diese Ergebnisse bilden Basiswissen für das Management von Rentieren in Hinsicht auf die stattfindende globale Erwärmung.},\n\tnumber = {1},\n\turldate = {2018-06-11},\n\tjournal = {Basic and Applied Ecology},\n\tauthor = {Mårell, Anders and Hofgaard, Annika and Danell, Kjell},\n\tmonth = jan,\n\tyear = {2006},\n\tnote = {00057},\n\tkeywords = {\\#nosource, Alpine, Growing season length, L., Nutrient quality, Patterns, Scale-dependency, Spatial, Sub-arctic, Temporal},\n\tpages = {13--30},\n}\n\n\n\n\n\n Summary Growing season nutrient dynamics of four reindeer forage species (Betula nana, Eriophorum angustifolium, Rumex acetosa and Vaccinium myrtillus) were studied in a mountainous sub-arctic landscape in N Sweden. Changes in nitrogen (N), phosphorus (P) and fibre (ADF) concentrations in leaves and shoots were analysed (from a reindeer foraging perspective) along four ecological gradients significant to regional and local snowmelt regimes: season, oceanicity, altitude, and snow-patch retreat. N and P concentrations showed marked seasonal variations with peaks occurring from the middle of June to the end of July depending on species and snowmelt progression. The seasonal pattern for ADF concentrations, as well as differences between snowmelt regimes, were less consistent and showed large differences between species. N concentrations increased along snowmelt gradients at small (within snow-patches) and medium (along altitude gradients) spatial scales. Furthermore, variations in N concentrations were temporally and spatially scale-dependent, which underlines the importance of scale for understanding plant nutrient dynamics in sub-arctic and alpine systems, as well for plant–animal interactions. The greatest temporal and spatial differences in nutrient quality were observed early in the season, i.e., at the time of highest nutrient requirements for reindeer. Climate-induced changes of the start and the progress of the growing season may result in significant consequences to the development of calves and subsequently to the population demography of reindeer, mediated through spatial and temporal changes in the distribution of high quality food. These results provide basic knowledge for reindeer management in the light of the ongoing global warming. Zusammenfassung Die Nährstoffdynamiken in der Wachstumsperiode wurden bei vier Arten von Rentierfutterpflanzen (Betula nana, Eriophorum angustifolium, Rumex acetosa, Vaccinium myrtillus) in einer bergigen subarktischen Landschaft N-Schwedens untersucht. Die Veränderungen der Konzentrationen von Stickstoff (N), Phosphor (P) und Fasern (ADF) in den Blättern und Trieben wurden entlang von vier ökologischen Gradienten analysiert, die für regionale und lokale Schneeschmelzeregimes bezeichnend sind: Jahreszeit, Ozeanität, Höhe und Schneefleckenrefugien. Die N- und P-Konzentrationen zeigten deutliche saisonale Variationen mit Spitzen, die zwischen Mitte Juni und Ende Juli auftraten, abhängig von Art und Fortschritt der Schneeschmelze. Das saisonale Muster der ADF-Konzentrationen sowie die Unterschiede zwischen den Schneeschmelzeregimes waren weniger konsistent und zeigten große Unterschiede zwischen den Arten. Die N-Konzentrationen stiegen entlang von Schneeschmelzegradienten auf kleinen (innerhalb von Schneeflecken) und mittleren (entlang von Höhengradienten) räumlichen Skalen an. Darüber hinaus waren die Variationen in den N-Konzentrationen zeitlich und räumlich skalenabhängig. Dies unterstreicht die Wichtigkeit der Skala für das Verständnis der Dynamiken von Pflanzennährstoffen in subarktischen und alpinen Systemen, sowie der Pflanze-Tier-Interaktionen. Die größten zeitlichen und räumlichen Unterschiede in der Nährstoffqualität wurden früh in der Saison beobachtet, d. h. zur Zeit des höchsten Nährstoffbedarfs der Rentiere. Klimainduzierte Veränderungen des Beginns und Verlaufs der Wachstumssaison können signifikante Konsequenzen für die Entwicklung von Kälbern und infolgedessen für die Populationsdemografie der Rentiere zum Ergebnis haben, vermittelt durch räumliche und zeitliche Veränderungen in der Verbreitung von Futter hoher Qualität. Diese Ergebnisse bilden Basiswissen für das Management von Rentieren in Hinsicht auf die stattfindende globale Erwärmung.\n
\n\n\n\n \n\n \n \n \n \n \n \n A comparison of chironomid biostratigraphy from Lake Vuolep Njakajaure with vegetation, lake-level, and climate changes in Abisko National Park, Sweden.\n \n \n \n \n\n\n \n Heinrichs, M.; Barnekow, L.; and Rosenberg, S.\n\n\n \n\n\n\n Journal of Paleolimnology, 36(2): 119–131. August 2006.\n 00011\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{heinrichs_comparison_2006,\n\ttitle = {A comparison of chironomid biostratigraphy from {Lake} {Vuolep} {Njakajaure} with vegetation, lake-level, and climate changes in {Abisko} {National} {Park}, {Sweden}},\n\tvolume = {36},\n\tissn = {0921-2728, 1573-0417},\n\turl = {https://link.springer.com/article/10.1007/s10933-006-0010-x},\n\tdoi = {10.1007/s10933-006-0010-x},\n\tabstract = {Chironomid remains from the sediment of Lake Vuolep Njakajaure reflect limnological conditions resulting from changing climate and vegetation throughout the Holocene, but do not strictly follow accepted climate trends or the vegetation history based on regional pollen and macrofossil analyses. Chironomid community changes appear to be influenced by organic nutrient input from the surrounding catchment vegetation and lake hydrology, both of which are indirectly responding to some combination of climate change, hypolimnetic oxygen concentration, and changes in basin morphology. The chironomid-based quantitative mean July air-temperature reconstruction differs from other regional quantitative records; this discrepancy is likely related to limnological conditions particular to Lake Vuolep Njakajaure. Comparison of a northern Swedish temperature transfer function and one from western Canada reveals differences in the mean July air-temperature optima of several common taxa, suggesting that the existing conservative estimates of Holocene climate change in northern Sweden may be underestimated due to the limited temperature gradient captured by the Swedish training set.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2018-06-11},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Heinrichs, Markus and Barnekow, Lena and Rosenberg, Sandra},\n\tmonth = aug,\n\tyear = {2006},\n\tnote = {00011},\n\tkeywords = {\\#nosource},\n\tpages = {119--131},\n}\n\n\n\n\n\n Chironomid remains from the sediment of Lake Vuolep Njakajaure reflect limnological conditions resulting from changing climate and vegetation throughout the Holocene, but do not strictly follow accepted climate trends or the vegetation history based on regional pollen and macrofossil analyses. Chironomid community changes appear to be influenced by organic nutrient input from the surrounding catchment vegetation and lake hydrology, both of which are indirectly responding to some combination of climate change, hypolimnetic oxygen concentration, and changes in basin morphology. The chironomid-based quantitative mean July air-temperature reconstruction differs from other regional quantitative records; this discrepancy is likely related to limnological conditions particular to Lake Vuolep Njakajaure. Comparison of a northern Swedish temperature transfer function and one from western Canada reveals differences in the mean July air-temperature optima of several common taxa, suggesting that the existing conservative estimates of Holocene climate change in northern Sweden may be underestimated due to the limited temperature gradient captured by the Swedish training set.\n
\n\n\n\n \n\n \n \n \n \n \n \n Spatial Heterogeneity and Hierarchical Feeding Habitat Selection by Reindeer.\n \n \n \n \n\n\n \n Mårell, A.; and Edenius, L.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 38(3): 413–420. August 2006.\n 00035\n\n\n\n
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\n\n\n@article{marell_spatial_2006,\n\ttitle = {Spatial {Heterogeneity} and {Hierarchical} {Feeding} {Habitat} {Selection} by {Reindeer}},\n\tvolume = {38},\n\tissn = {1523-0430},\n\turl = {http://www.bioone.org/doi/abs/10.1657/1523-0430(2006)38%5B413:SHAHFH%5D2.0.CO%3B2},\n\tdoi = {10.1657/1523-0430(2006)38[413:SHAHFH]2.0.CO;2},\n\tabstract = {Reindeer, Rangifer tarandus, live in subarctic and alpine environments with spatially and temporally heterogeneous resource distribution. In this study, we used a hierarchical approach to test whether reindeer responded to spatial heterogeneity during the plant growing season (divided into three distinct periods) in a mountainous subarctic environment in northern Sweden. A reindeer herd in northern Sweden was surveyed using radio-telemetry (8 female reindeer) and the selection of feeding habitats by observing individuals/groups (135 observations) using laser range-finding binoculars. Reindeer selected feeding areas (evaluated at 5-km grid size), as well as feeding habitats (evaluated at 0.5- and 1-km grid size) during spring, in response to high terrain ruggedness and habitat heterogeneity. Reindeer switched during summer to select against terrain ruggedness and habitat heterogeneity at the level of feeding habitats, while preferring southward facing habitats. During autumn, a broader spectrum of feeding habitats was used. We conclude that reindeer seem to adopt a hierarchical strategy in agreement with general foraging theory, and are capable of responding to seasonal changes in resource distribution occurring across spatial scales. Furthermore, our results support the idea that spatial heterogeneity is an important factor to large-sized herbivores at high and intermediate levels of habitat selection. Conservation of large continuous and undeveloped landscapes is an important management goal, as they provide a wide range of habitats necessary for animals such as reindeer that use large territories.},\n\tnumber = {3},\n\turldate = {2018-06-11},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Mårell, Anders and Edenius, Lars},\n\tmonth = aug,\n\tyear = {2006},\n\tnote = {00035},\n\tkeywords = {\\#nosource},\n\tpages = {413--420},\n}\n\n\n\n\n\n Reindeer, Rangifer tarandus, live in subarctic and alpine environments with spatially and temporally heterogeneous resource distribution. In this study, we used a hierarchical approach to test whether reindeer responded to spatial heterogeneity during the plant growing season (divided into three distinct periods) in a mountainous subarctic environment in northern Sweden. A reindeer herd in northern Sweden was surveyed using radio-telemetry (8 female reindeer) and the selection of feeding habitats by observing individuals/groups (135 observations) using laser range-finding binoculars. Reindeer selected feeding areas (evaluated at 5-km grid size), as well as feeding habitats (evaluated at 0.5- and 1-km grid size) during spring, in response to high terrain ruggedness and habitat heterogeneity. Reindeer switched during summer to select against terrain ruggedness and habitat heterogeneity at the level of feeding habitats, while preferring southward facing habitats. During autumn, a broader spectrum of feeding habitats was used. We conclude that reindeer seem to adopt a hierarchical strategy in agreement with general foraging theory, and are capable of responding to seasonal changes in resource distribution occurring across spatial scales. Furthermore, our results support the idea that spatial heterogeneity is an important factor to large-sized herbivores at high and intermediate levels of habitat selection. Conservation of large continuous and undeveloped landscapes is an important management goal, as they provide a wide range of habitats necessary for animals such as reindeer that use large territories.\n
\n\n\n\n \n\n \n \n \n \n \n \n Historical Changes in Arctic Freshwater Ecosystems.\n \n \n \n \n\n\n \n Prowse, T. D.; Wrona, F. J.; Reist, J. D.; Gibson, J. J.; Hobbie, J. E.; Lévesque, L. M. J.; and Vincent, W. F.\n\n\n \n\n\n\n AMBIO: A Journal of the Human Environment, 35(7): 339–346. November 2006.\n 00018\n\n\n\n
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\n\n\n@article{prowse_historical_2006,\n\ttitle = {Historical {Changes} in {Arctic} {Freshwater} {Ecosystems}},\n\tvolume = {35},\n\tissn = {0044-7447},\n\turl = {http://www.bioone.org/doi/abs/10.1579/0044-7447(2006)35[339:HCIAFE]2.0.CO;2},\n\tdoi = {10.1579/0044-7447(2006)35[339:HCIAFE]2.0.CO;2},\n\tabstract = {Various types of ecosystem-based climate proxies have been used to assess past arctic change. Although lotic records are relatively poor because of the constant reworking of riverine material, high-quality lentic data have been assembled back to the end of the Pleistocene and deglaciation of the circumpolar Arctic. In general, climatic variations in the Holocene, partly due to changes in the shrinking effect of glacier coverage, produced significant temporal and spatial variations in arctic hydrology and freshwater ecosystems. Of particular note were the vast expansions of northern peatlands during major protracted periods of wetting. More recent lake biota and sedimentiological data reflect the general warming trend that has occurred over the last one to two centuries and indicate major changes to freshwater characteristics such as ice-cover duration and thermal stratification. Such data provide an excellent baseline against which future effects of climate change can be both projected and measured.},\n\tnumber = {7},\n\turldate = {2018-06-11},\n\tjournal = {AMBIO: A Journal of the Human Environment},\n\tauthor = {Prowse, Terry D. and Wrona, Frederick J. and Reist, James D. and Gibson, John J. and Hobbie, John E. and Lévesque, Lucie M. J. and Vincent, Warwick F.},\n\tmonth = nov,\n\tyear = {2006},\n\tnote = {00018},\n\tkeywords = {\\#nosource},\n\tpages = {339--346},\n}\n\n\n\n\n\n Various types of ecosystem-based climate proxies have been used to assess past arctic change. Although lotic records are relatively poor because of the constant reworking of riverine material, high-quality lentic data have been assembled back to the end of the Pleistocene and deglaciation of the circumpolar Arctic. In general, climatic variations in the Holocene, partly due to changes in the shrinking effect of glacier coverage, produced significant temporal and spatial variations in arctic hydrology and freshwater ecosystems. Of particular note were the vast expansions of northern peatlands during major protracted periods of wetting. More recent lake biota and sedimentiological data reflect the general warming trend that has occurred over the last one to two centuries and indicate major changes to freshwater characteristics such as ice-cover duration and thermal stratification. Such data provide an excellent baseline against which future effects of climate change can be both projected and measured.\n
\n\n\n\n \n\n \n \n \n \n \n \n Summer feeding behaviour of reindeer.\n \n \n \n \n\n\n \n Mårell, A.\n\n\n \n\n\n\n Ph.D. Thesis, Swedish University of Agricultural Sciences, Umeå, Sweden, September 2006.\n 00005\n\n\n\n
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\n\n\n@phdthesis{marell_summer_2006,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral thesis},\n\ttitle = {Summer feeding behaviour of reindeer},\n\turl = {https://pub.epsilon.slu.se/1203/},\n\tabstract = {Reindeer (Rangifer tarandus L.) plays an important role ecologically, economically, as well as culturally in northern Fennoscandia, where reindeer husbandry traditionally has considered winter to be the bottleneck for reindeer. Recent studies have shown that summer feeding conditions control reindeer population dynamics through indirect effects on winter survival and reproductive success. My thesis is unique as it analyses seasonal plant nutrient dynamics, their spatial patterns and reindeer summer foraging behaviour at different levels simultaneously. The aim was to test the underlying assumptions behind the hypothesis that reindeer select the new emerging growth (highly digestible and protein rich) and move into new areas as the emergence of new growth proceeds along climatic gradients. The studies were done in a mountainous landscape of sub-arctic northern Sweden used by the semi-domesticated reindeer herd belonging to Gabna Sami community. The study on plant nutrient dynamics of four forage species (Betula nana L., Eriophorum angustifolium L., Rumex acetosa L. and Vaccinium myrtillus L.) revealed that plant nitrogen concentrations (and thus protein content) related to snowmelt patterns. It was further shown that reindeer selected areas with high landcover diversity, and thus might respond to any landscape heterogeneity that results from varying snowmelt patterns. Within landscapes, reindeer selected species rich plant communities with high abundance of preferred food plants (deciduous shrubs, herbs and graminoids) and fed where food biomass was high, predominantly that of birch and willow species. Contrary to predictions of the tested hypothesis, it was concluded that reindeer responded to food quantity rather than quality at intermediate (i.e., within plant communities) levels of feeding habitat selection. Feeding habitat selection at higher (i.e., feeding area and plant community selection) and lower (i.e., plant species and parts selection) levels indicated the importance of food quality and was thus in agreement with the tested hypothesis. My results have implications for land management as they show the importance of maintaining heterogeneous alpine landscapes for reindeer husbandry. Furthermore, reindeer husbandry needs to be practised at a level that maintain species rich and diverse plant communities. These plant communities were shown to be important feeding habitats, at the same time as they may contribute to nature conservation goals.},\n\tlanguage = {eng},\n\turldate = {2018-06-11},\n\tschool = {Swedish University of Agricultural Sciences},\n\tauthor = {Mårell, Anders},\n\tcollaborator = {Hofgaard, Annika},\n\tmonth = sep,\n\tyear = {2006},\n\tnote = {00005},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n Reindeer (Rangifer tarandus L.) plays an important role ecologically, economically, as well as culturally in northern Fennoscandia, where reindeer husbandry traditionally has considered winter to be the bottleneck for reindeer. Recent studies have shown that summer feeding conditions control reindeer population dynamics through indirect effects on winter survival and reproductive success. My thesis is unique as it analyses seasonal plant nutrient dynamics, their spatial patterns and reindeer summer foraging behaviour at different levels simultaneously. The aim was to test the underlying assumptions behind the hypothesis that reindeer select the new emerging growth (highly digestible and protein rich) and move into new areas as the emergence of new growth proceeds along climatic gradients. The studies were done in a mountainous landscape of sub-arctic northern Sweden used by the semi-domesticated reindeer herd belonging to Gabna Sami community. The study on plant nutrient dynamics of four forage species (Betula nana L., Eriophorum angustifolium L., Rumex acetosa L. and Vaccinium myrtillus L.) revealed that plant nitrogen concentrations (and thus protein content) related to snowmelt patterns. It was further shown that reindeer selected areas with high landcover diversity, and thus might respond to any landscape heterogeneity that results from varying snowmelt patterns. Within landscapes, reindeer selected species rich plant communities with high abundance of preferred food plants (deciduous shrubs, herbs and graminoids) and fed where food biomass was high, predominantly that of birch and willow species. Contrary to predictions of the tested hypothesis, it was concluded that reindeer responded to food quantity rather than quality at intermediate (i.e., within plant communities) levels of feeding habitat selection. Feeding habitat selection at higher (i.e., feeding area and plant community selection) and lower (i.e., plant species and parts selection) levels indicated the importance of food quality and was thus in agreement with the tested hypothesis. My results have implications for land management as they show the importance of maintaining heterogeneous alpine landscapes for reindeer husbandry. Furthermore, reindeer husbandry needs to be practised at a level that maintain species rich and diverse plant communities. These plant communities were shown to be important feeding habitats, at the same time as they may contribute to nature conservation goals.\n
\n\n\n\n \n\n \n \n \n \n \n \n Fox Sparrow foraging on a king bolete mushroom.\n \n \n \n \n\n\n \n Schiller, A. M.; and Larson, K. W.\n\n\n \n\n\n\n Northwest Naturalist, 87(3): 252. 2006.\n 00000\n\n\n\n
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\n\n\n\n@article{schiller_fox_2006,\n\ttitle = {Fox {Sparrow} foraging on a king bolete mushroom},\n\tvolume = {87},\n\tissn = {1938-5315},\n\turl = {http://www.bioone.org/doi/full/10.1898/1051-1733(2006)87%5B252%3AFSFOAK%5D2.0.CO%3B2},\n\tdoi = {10.1898/1051-1733(2006)87[252:FSFOAK]2.0.CO;2},\n\tnumber = {3},\n\tjournal = {Northwest Naturalist},\n\tauthor = {Schiller, Anja M. and Larson, Keith W.},\n\tyear = {2006},\n\tnote = {00000},\n\tkeywords = {\\#nosource, Boletus edulis, Fox Sparrow, Passerella illiaca, mycophagy},\n\tpages = {252},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Sphagnum modifies climate-change impacts on subarctic vascular bog plants.\n \n \n \n \n\n\n \n Dorrepaal, E.; Aerts, R.; Cornelissen, J. H. C.; Van Logtestijn, R. S. P.; and Callaghan, T. V.\n\n\n \n\n\n\n Functional Ecology, 20(1): 31–41. February 2006.\n 00036\n\n\n\n
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\n\n\n@article{dorrepaal_sphagnum_2006,\n\ttitle = {Sphagnum modifies climate-change impacts on subarctic vascular bog plants},\n\tvolume = {20},\n\tissn = {1365-2435},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2006.01076.x/abstract},\n\tdoi = {10.1111/j.1365-2435.2006.01076.x},\n\tabstract = {* 1Vascular plant growth forms in northern peatlands differ in their strategies to cope with the harsh climate, low nutrient availability and progressively increasing height of the Sphagnum carpet in which they grow. Climate change may therefore affect growth forms differentially, both directly and through changes in the length growth of Sphagnum mosses. However, the role of mosses as modifiers of climate-change effects on vascular plants has been largely overlooked so far. We investigated the direct and Sphagnum-mediated effects of experimental changes in summer, winter and spring climate on four species of contrasting growth forms (evergreen and deciduous shrubs, graminoid, forb) in a subarctic bog, by studying their biomass and nitrogen losses through leaf litter, and the length growth of the two shrubs.\n* 2Direct and indirect effects of summer warming differed among the growth forms. Enhanced Sphagnum overgrowth of leaves due to summer warming initially stimulated leaf litter losses of the evergreen shrub Empetrum nigrum. However, changes in its shoot morphology, related to an apparent small increase in its length growth, prevented further effects. A stronger increase in stem growth of the deciduous shrub Betula nana in response to summer warming directly reduced its leaf litter mass, N concentration and N losses. The changed allocation prevented indirect, Sphagnum-mediated effects on its leaf and N dynamics through overgrowth of buds. In contrast, leaf litter mass, N concentrations or N losses of the forb Rubus chamaemorus and the graminoid Calamagrostis lapponica were not affected by summer warming or enhanced Sphagnum growth.\n* 3Increases in winter snow cover, with or without spring warming, did not affect shrub growth, nor the total shoot leaf litter mass or N dynamics of any of the growth forms.\n* 4Altogether, summer warming is likely to enhance Sphagnum overgrowth of small shrubs with a limited growth response such as Empetrum. Moreover, increased vertical growth may allow Sphagnum to keep pace with inclined growing, responsive shrubs such as Betula. This might prevent net longer-term positive effects of summer warming on the vascular plant canopy height. However, leaf litter and N losses are more likely to be affected by direct warming effects on shoot morphology and allocation than by Sphagnum growth. The different responses of the growth forms to summer warming suggest that both direct and Sphagnum-mediated climate effects have the potential to change the vascular plant community and N dynamics in peatlands.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-08},\n\tjournal = {Functional Ecology},\n\tauthor = {Dorrepaal, E. and Aerts, R. and Cornelissen, J. H. C. and Van Logtestijn, R. S. P. and Callaghan, T. V.},\n\tmonth = feb,\n\tyear = {2006},\n\tnote = {00036},\n\tkeywords = {\\#nosource, global warming, leaf litter, peatlands, plant growth form, snow cover},\n\tpages = {31--41},\n}\n\n\n\n\n\n * 1Vascular plant growth forms in northern peatlands differ in their strategies to cope with the harsh climate, low nutrient availability and progressively increasing height of the Sphagnum carpet in which they grow. Climate change may therefore affect growth forms differentially, both directly and through changes in the length growth of Sphagnum mosses. However, the role of mosses as modifiers of climate-change effects on vascular plants has been largely overlooked so far. We investigated the direct and Sphagnum-mediated effects of experimental changes in summer, winter and spring climate on four species of contrasting growth forms (evergreen and deciduous shrubs, graminoid, forb) in a subarctic bog, by studying their biomass and nitrogen losses through leaf litter, and the length growth of the two shrubs. * 2Direct and indirect effects of summer warming differed among the growth forms. Enhanced Sphagnum overgrowth of leaves due to summer warming initially stimulated leaf litter losses of the evergreen shrub Empetrum nigrum. However, changes in its shoot morphology, related to an apparent small increase in its length growth, prevented further effects. A stronger increase in stem growth of the deciduous shrub Betula nana in response to summer warming directly reduced its leaf litter mass, N concentration and N losses. The changed allocation prevented indirect, Sphagnum-mediated effects on its leaf and N dynamics through overgrowth of buds. In contrast, leaf litter mass, N concentrations or N losses of the forb Rubus chamaemorus and the graminoid Calamagrostis lapponica were not affected by summer warming or enhanced Sphagnum growth. * 3Increases in winter snow cover, with or without spring warming, did not affect shrub growth, nor the total shoot leaf litter mass or N dynamics of any of the growth forms. * 4Altogether, summer warming is likely to enhance Sphagnum overgrowth of small shrubs with a limited growth response such as Empetrum. Moreover, increased vertical growth may allow Sphagnum to keep pace with inclined growing, responsive shrubs such as Betula. This might prevent net longer-term positive effects of summer warming on the vascular plant canopy height. However, leaf litter and N losses are more likely to be affected by direct warming effects on shoot morphology and allocation than by Sphagnum growth. The different responses of the growth forms to summer warming suggest that both direct and Sphagnum-mediated climate effects have the potential to change the vascular plant community and N dynamics in peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n The relative importance of allochthonous and autochthonous food resources in tropical streams.\n \n \n \n \n\n\n \n Lau, D. C. P.; Leung, K. M. Y.; and Dudgeon, D.\n\n\n \n\n\n\n In Bulletin of the North American Benthological Society, volume 23, pages 125. North American Benthological Society, 2006.\n \n\n\n\n
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\n\n\n\n@incollection{lau_relative_2006,\n\ttitle = {The relative importance of allochthonous and autochthonous food resources in tropical streams},\n\tvolume = {23},\n\turl = {https://hub.hku.hk/handle/10722/112017},\n\turldate = {2017-05-27},\n\tbooktitle = {Bulletin of the {North} {American} {Benthological} {Society}},\n\tpublisher = {North American Benthological Society},\n\tauthor = {Lau, Danny Chun Pong and Leung, Kenneth Mei Yee and Dudgeon, David},\n\tyear = {2006},\n\tkeywords = {\\#nosource},\n\tpages = {125},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n Distribution of diatoms, chironomids and cladocera in surface sediments of thirty mountain lakes in south-eastern Switzerland.\n \n \n \n\n\n \n Bigler, C.; Heiri, O.; Krskova, R.; Lotter, A. F.; and Sturm, M.\n\n\n \n\n\n\n Aquatic Sciences, 68(2): 154–171. June 2006.\n \n\n\n\n
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\n\n\n@article{bigler_distribution_2006,\n\ttitle = {Distribution of diatoms, chironomids and cladocera in surface sediments of thirty mountain lakes in south-eastern {Switzerland}},\n\tvolume = {68},\n\tissn = {1015-1621},\n\tdoi = {10.1007/s00027-006-0813-x},\n\tabstract = {Surface sediments from 30 mountain lakes in south-eastern Switzerland (Engadine, Grisons) were analysed for subfossil diatom, chironomid, and cladoceran assemblages. Ordination techniques were used to identify relevant physical and chemical environmental parameters that best explain the distribution of these biota in the studied lakes. Diatom assemblage composition showed a strong relationship with physical (e.g., lake depth, temperature, organic content of surface sediments) and chemical variables (e.g., lake-water pH, alkalinity, silica concentration). The greatest variance in chironomid and cladoceran assemblages is explained by dissolved organic carbon (DOC) content of lake water, temperature, and the organic content of surface sediments, all parameters which are highly correlated with lake elevation. Increasing lake depth is reflected in diatom and cladoceran assemblages by higher percentages of planktonic species, whereas chironomid assemblages in the deep Engadine lakes are characterised by a high proportion of lotic taxa. In contrast to similar studies in the Northern and Southern Alps, subfossil assemblages in the Engadine mountain lakes showed a strong relationship with DOC, which in these weakly buffered lakes is negatively correlated with altitude. According to our findings, chironomid and cladocera remains have a considerable potential as quantitative palaeotemperature indicators in the Engadine area. This potential is somewhat weaker for diatoms which seem to be more strongly influenced by water chemistry and lake bathymetry.},\n\tlanguage = {English},\n\tnumber = {2},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Bigler, C. and Heiri, O. and Krskova, R. and Lotter, A. F. and Sturm, M.},\n\tmonth = jun,\n\tyear = {2006},\n\tkeywords = {\\#nosource, Engadine, air temperatures, alpine lakes, arctic fennoscandian lakes, chironomids, chrysophyte cyst assemblages, cladocera, diatoms, holocene environmental-changes, mountain lakes, northern sweden, quantitative indicators, swiss alps, trophic history, water chemistry, water temperature},\n\tpages = {154--171},\n}\n\n\n\n\n\n Surface sediments from 30 mountain lakes in south-eastern Switzerland (Engadine, Grisons) were analysed for subfossil diatom, chironomid, and cladoceran assemblages. Ordination techniques were used to identify relevant physical and chemical environmental parameters that best explain the distribution of these biota in the studied lakes. Diatom assemblage composition showed a strong relationship with physical (e.g., lake depth, temperature, organic content of surface sediments) and chemical variables (e.g., lake-water pH, alkalinity, silica concentration). The greatest variance in chironomid and cladoceran assemblages is explained by dissolved organic carbon (DOC) content of lake water, temperature, and the organic content of surface sediments, all parameters which are highly correlated with lake elevation. Increasing lake depth is reflected in diatom and cladoceran assemblages by higher percentages of planktonic species, whereas chironomid assemblages in the deep Engadine lakes are characterised by a high proportion of lotic taxa. In contrast to similar studies in the Northern and Southern Alps, subfossil assemblages in the Engadine mountain lakes showed a strong relationship with DOC, which in these weakly buffered lakes is negatively correlated with altitude. According to our findings, chironomid and cladocera remains have a considerable potential as quantitative palaeotemperature indicators in the Engadine area. This potential is somewhat weaker for diatoms which seem to be more strongly influenced by water chemistry and lake bathymetry.\n
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\n \n \n\n \n \n \n \n \n \n A field assessment of the Spalinger and Hobbs mechanistic foraging model: free-ranging moose in winter.\n \n \n \n \n\n\n \n Nordengren, C; and Ball, J. P\n\n\n \n\n\n\n Canadian Journal of Zoology, 83(4): 518–526. April 2005.\n 00006\n\n\n\n
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\n\n\n@article{nordengren_field_2005,\n\ttitle = {A field assessment of the {Spalinger} and {Hobbs} mechanistic foraging model: free-ranging moose in winter},\n\tvolume = {83},\n\tissn = {0008-4301},\n\tshorttitle = {A field assessment of the {Spalinger}{Hobbs} mechanistic foraging model},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/z05-029},\n\tdoi = {10.1139/z05-029},\n\tabstract = {The mechanistic foraging models introduced by Spalinger and Hobbs in 1992 have been very influential in studies of herbivory at a variety of scales. However, almost no field study has evaluated whether the assumption regarding invariability of parameters with time holds for large herbivores with long foraging bouts, and most studies have obtained the model parameters from very short trials. We used free-ranging moose, Alces alces (L., 1758), to test this assumption of invariability and to compare intake calculated by the SpalingerHobbs model using parameters obtained from 10-min trials with intake calculated using data obtained from entire bouts. Our results revealed that the invariance assumption was not fully met: moose increased bite and chew rates and took smaller bites the longer a bite or chew sequence lasted, which resulted in declining intake rates. As a result, the original model misestimated intake by more than double for mountain birch (Betula pubescens ssp. czerepanovii (Orlova) Hämet-Ahti) a..., Les modèles mécanistes de recherche de nourriture introduits par Spalinger et Hobbs en 1992 ont eu une grande influence sur les études de la phytophagie à plusieurs échelles. Néanmoins, à peu aucune étude de terrain n'a évalué si les présuppositions concernant l'invariance des paramètres dans le temps tient chez les grands herbivores qui ont de longues périodes d'alimentation; la plupart des études ont, en effet, mesuré les paramètres des modèles sur de très courts essais. Nous avons testé cette invariance chez des orignaux, Alces alces (L., 1758), en liberté et comparé l'ingestion calculée par le modèle SpalingerHobbs à l'aide de paramètres obtenus d'essais de 10 minutes à l'ingestion calculée sur des sessions entières. Nos résultats indiquent que la présupposition d'invariance ne s'applique pas entièrement : les orignaux augmentent leurs taux de morsure et de mastication et prennent de plus petites bouchées à mesure que la séquence de morsures ou de mastication s'allonge, ce qui réduit les taux d'inges...},\n\tnumber = {4},\n\turldate = {2018-06-11},\n\tjournal = {Canadian Journal of Zoology},\n\tauthor = {Nordengren, C and Ball, John P},\n\tmonth = apr,\n\tyear = {2005},\n\tnote = {00006},\n\tkeywords = {\\#nosource},\n\tpages = {518--526},\n}\n\n\n\n\n\n The mechanistic foraging models introduced by Spalinger and Hobbs in 1992 have been very influential in studies of herbivory at a variety of scales. However, almost no field study has evaluated whether the assumption regarding invariability of parameters with time holds for large herbivores with long foraging bouts, and most studies have obtained the model parameters from very short trials. We used free-ranging moose, Alces alces (L., 1758), to test this assumption of invariability and to compare intake calculated by the SpalingerHobbs model using parameters obtained from 10-min trials with intake calculated using data obtained from entire bouts. Our results revealed that the invariance assumption was not fully met: moose increased bite and chew rates and took smaller bites the longer a bite or chew sequence lasted, which resulted in declining intake rates. As a result, the original model misestimated intake by more than double for mountain birch (Betula pubescens ssp. czerepanovii (Orlova) Hämet-Ahti) a..., Les modèles mécanistes de recherche de nourriture introduits par Spalinger et Hobbs en 1992 ont eu une grande influence sur les études de la phytophagie à plusieurs échelles. Néanmoins, à peu aucune étude de terrain n'a évalué si les présuppositions concernant l'invariance des paramètres dans le temps tient chez les grands herbivores qui ont de longues périodes d'alimentation; la plupart des études ont, en effet, mesuré les paramètres des modèles sur de très courts essais. Nous avons testé cette invariance chez des orignaux, Alces alces (L., 1758), en liberté et comparé l'ingestion calculée par le modèle SpalingerHobbs à l'aide de paramètres obtenus d'essais de 10 minutes à l'ingestion calculée sur des sessions entières. Nos résultats indiquent que la présupposition d'invariance ne s'applique pas entièrement : les orignaux augmentent leurs taux de morsure et de mastication et prennent de plus petites bouchées à mesure que la séquence de morsures ou de mastication s'allonge, ce qui réduit les taux d'inges...\n
\n\n\n\n \n\n \n \n \n \n \n Contribution of sediment respiration to summer CO2 emission from low productive boreal and subarctic lakes.\n \n \n \n\n\n \n Algesten, G.; Sobek, S.; Bergström, A.; Jonsson, A.; Tranvik, L. J.; and Jansson, M.\n\n\n \n\n\n\n Microbial Ecology, 50(4): 529–535. November 2005.\n \n\n\n\n
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\n\n\n@article{algesten_contribution_2005,\n\ttitle = {Contribution of sediment respiration to summer {CO2} emission from low productive boreal and subarctic lakes},\n\tvolume = {50},\n\tissn = {0095-3628},\n\tdoi = {10.1007/s00248-005-5007-x},\n\tabstract = {We measured sediment production of carbon dioxide (CO2) and methane (CH4) and the net flux of CO2 across the surfaces of 15 boreal and subarctic lakes of different humic contents. Sediment respiration measurements were made in situ under ambient light conditions. The flux of CO2 between sediment and water varied between an uptake of 53 and an efflux of 182 mg C m(-2) day(-1) from the sediments. The mean respiration rate for sediments in contact with the upper mixed layer (SedR) was positively correlated to dissolved organic carbon (DOC) concentration in the water (r(2) = 0.61). The net flux of CO2 across the lake surface [net ecosystem exchange (NEE)] was also closely correlated to DOC concentration in the upper mixed layer (r(2) = 0.73). The respiration in the water column was generally 10-fold higher per unit lake area compared to sediment respiration. Lakes with DOC concentrations {\\textless} 5.6 mg L-1 had net consumption of CO2 in the sediments, which we ascribe to benthic primary production. Only lakes with very low DOC concentrations were net autotrophic ({\\textless} 2.6 mg L-1) due to the dominance of dissolved allochthonous organic carbon in the water as an energy source for aquatic organisms. In addition to previous findings of allochthonous organic matter as an important driver of heterotrophic metabolism in the water column of lakes, this study suggests that sediment metabolism is also highly dependent on allochthonous carbon sources.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Microbial Ecology},\n\tauthor = {Algesten, G. and Sobek, S. and Bergström, Ann-Kristin and Jonsson, A. and Tranvik, L. J. and Jansson, M.},\n\tmonth = nov,\n\tyear = {2005},\n\tkeywords = {\\#nosource, Mineralization, allochthonous organic-carbon, bacterioplankton production, carbon-dioxide supersaturation, clear-water lakes, large humic lake, methane, northern sweden, temperate, wisconsin},\n\tpages = {529--535},\n}\n\n\n\n\n\n We measured sediment production of carbon dioxide (CO2) and methane (CH4) and the net flux of CO2 across the surfaces of 15 boreal and subarctic lakes of different humic contents. Sediment respiration measurements were made in situ under ambient light conditions. The flux of CO2 between sediment and water varied between an uptake of 53 and an efflux of 182 mg C m(-2) day(-1) from the sediments. The mean respiration rate for sediments in contact with the upper mixed layer (SedR) was positively correlated to dissolved organic carbon (DOC) concentration in the water (r(2) = 0.61). The net flux of CO2 across the lake surface [net ecosystem exchange (NEE)] was also closely correlated to DOC concentration in the upper mixed layer (r(2) = 0.73). The respiration in the water column was generally 10-fold higher per unit lake area compared to sediment respiration. Lakes with DOC concentrations \\textless 5.6 mg L-1 had net consumption of CO2 in the sediments, which we ascribe to benthic primary production. Only lakes with very low DOC concentrations were net autotrophic (\\textless 2.6 mg L-1) due to the dominance of dissolved allochthonous organic carbon in the water as an energy source for aquatic organisms. In addition to previous findings of allochthonous organic matter as an important driver of heterotrophic metabolism in the water column of lakes, this study suggests that sediment metabolism is also highly dependent on allochthonous carbon sources.\n
\n\n\n\n \n\n \n \n \n \n \n \n A multi-proxy palaeoecological study of Alanen Laanijärvi, a boreal-forest lake in Swedish Lapland.\n \n \n \n \n\n\n \n Heinrichs, M. L.; Peglar, S. M.; Bigler, C.; and Birks, H. J. B.\n\n\n \n\n\n\n Boreas, 34(2): 192–206. May 2005.\n 00016\n\n\n\n
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\n\n\n@article{heinrichs_multi-proxy_2005,\n\ttitle = {A multi-proxy palaeoecological study of {Alanen} {Laanijärvi}, a boreal-forest lake in {Swedish} {Lapland}},\n\tvolume = {34},\n\tissn = {1502-3885},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1502-3885.2005.tb01015.x/abstract},\n\tdoi = {10.1111/j.1502-3885.2005.tb01015.x},\n\tabstract = {Heinrichs, M. L., Peglar, S. M., Bigler, C. \\& Birks, H. J. B. 2005 (May): A multi-proxy palaeoecological study of Alanen Laanijärvi, a boreal-forest lake in Swedish Lapland. Boreas, Vol. 34, pp. 192–206. Oslo. ISSN 0300–9483. Chironomids, pollen and spores were used to reconstruct Holocene aquatic and terrestrial environments at Alanen Laanijärvi, northern Sweden. Chironomid analysis revealed a pattern of limnological evolution from oligotrophic conditions in a relatively deep lake during 8.6 to 5.5 cal. kaBP, followed by a period of lake shallowing from 5.5 to 2.7 cal. ka BP. Increases in acidity and littoral habitat complexity may have occurred from 2.7cal. kaBP to the present, though some compositional changes may have resulted from human disturbance. Chironomid-inferred mean July air temperatures range between 9.8C in the Early Holocene to 11.3C in the Late Holocene. Limitations on chironomid-based quantitative temperature interpretations may exist because of low taxon richness. Diatoms were recovered from the upper sediments only, from about AD 1800. Pollen and spore analysis revealed an early colonizing vegetation of juniper, sedges and birch soon after local deglaciation, followed by birch forests until about 8.3 cal. kaBP. Alder stands occurred locally to 5.5 cal. kaBP, when pine and spruce forests developed and remain to the present day. These results suggest that little major terrestrial vegetation change may occur in some northern environments with predicted future global warming, where it is predicted to be most severe. Aquatic environments may, however, be greatly affected by a shift in precipitation regime, causing changes in allochthonous organic input, lake depth and possibly the amount of human activity or disturbance in the watershed.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-07},\n\tjournal = {Boreas},\n\tauthor = {Heinrichs, Markus L. and Peglar, Sylvia M. and Bigler, Christian and Birks, H. John B.},\n\tmonth = may,\n\tyear = {2005},\n\tnote = {00016},\n\tkeywords = {\\#nosource, aquatic invertebrates, chironomid assemblages, climate-change, holocene environmental-change, megafossil evidence, northern sweden, northwest-territories, quantitative indicators, tree-line area, vegetation history},\n\tpages = {192--206},\n}\n\n\n\n\n\n Heinrichs, M. L., Peglar, S. M., Bigler, C. & Birks, H. J. B. 2005 (May): A multi-proxy palaeoecological study of Alanen Laanijärvi, a boreal-forest lake in Swedish Lapland. Boreas, Vol. 34, pp. 192–206. Oslo. ISSN 0300–9483. Chironomids, pollen and spores were used to reconstruct Holocene aquatic and terrestrial environments at Alanen Laanijärvi, northern Sweden. Chironomid analysis revealed a pattern of limnological evolution from oligotrophic conditions in a relatively deep lake during 8.6 to 5.5 cal. kaBP, followed by a period of lake shallowing from 5.5 to 2.7 cal. ka BP. Increases in acidity and littoral habitat complexity may have occurred from 2.7cal. kaBP to the present, though some compositional changes may have resulted from human disturbance. Chironomid-inferred mean July air temperatures range between 9.8C in the Early Holocene to 11.3C in the Late Holocene. Limitations on chironomid-based quantitative temperature interpretations may exist because of low taxon richness. Diatoms were recovered from the upper sediments only, from about AD 1800. Pollen and spore analysis revealed an early colonizing vegetation of juniper, sedges and birch soon after local deglaciation, followed by birch forests until about 8.3 cal. kaBP. Alder stands occurred locally to 5.5 cal. kaBP, when pine and spruce forests developed and remain to the present day. These results suggest that little major terrestrial vegetation change may occur in some northern environments with predicted future global warming, where it is predicted to be most severe. Aquatic environments may, however, be greatly affected by a shift in precipitation regime, causing changes in allochthonous organic input, lake depth and possibly the amount of human activity or disturbance in the watershed.\n
\n\n\n\n \n\n \n \n \n \n \n \n Productivity of high-latitude lakes: climate effect inferred from altitude gradient.\n \n \n \n \n\n\n \n Karlsson, J.; Jonsson, A.; and Jansson, M.\n\n\n \n\n\n\n Global Change Biology, 11(5): 710–715. May 2005.\n 00073\n\n\n\n
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\n\n\n@article{karlsson_productivity_2005,\n\ttitle = {Productivity of high-latitude lakes: climate effect inferred from altitude gradient},\n\tvolume = {11},\n\tissn = {1365-2486},\n\tshorttitle = {Productivity of high-latitude lakes},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2005.00945.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2005.00945.x},\n\tabstract = {Climate change is predicted to be dramatic at high latitudes. Still, climate impact on high latitude lake ecosystems is poorly understood. We studied 15 subarctic lakes located in a climate gradient comprising an air temperature difference of about 6°C. We show that lake water productivity varied by one order of magnitude along the temperature gradient. This variation was mainly caused by variations in the length of the ice-free period and, more importantly, in the supply of organic carbon and inorganic nutrients, which followed differences in terrestrial vegetation cover along the gradient. The results imply that warming will have rapid effects on the productivity of high latitude lakes, by prolongation of ice-free periods. However, a more pronounced consequence will be a delayed stimulation of the productivity following upon changes of the lakes terrestrial surroundings and subsequent increasing input of elements that stimulate the production of lake biota.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-06},\n\tjournal = {Global Change Biology},\n\tauthor = {Karlsson, Jan and Jonsson, Anders and Jansson, Mats},\n\tmonth = may,\n\tyear = {2005},\n\tnote = {00073},\n\tkeywords = {\\#nosource, allochthonous carbon, bacterioplankton, catchment characteristics, climate change, energy mobilization, lake productivity, nutrients, phytoplankton, subarctic, temperature},\n\tpages = {710--715},\n}\n\n\n\n\n\n Climate change is predicted to be dramatic at high latitudes. Still, climate impact on high latitude lake ecosystems is poorly understood. We studied 15 subarctic lakes located in a climate gradient comprising an air temperature difference of about 6°C. We show that lake water productivity varied by one order of magnitude along the temperature gradient. This variation was mainly caused by variations in the length of the ice-free period and, more importantly, in the supply of organic carbon and inorganic nutrients, which followed differences in terrestrial vegetation cover along the gradient. The results imply that warming will have rapid effects on the productivity of high latitude lakes, by prolongation of ice-free periods. However, a more pronounced consequence will be a delayed stimulation of the productivity following upon changes of the lakes terrestrial surroundings and subsequent increasing input of elements that stimulate the production of lake biota.\n
\n\n\n\n \n\n \n \n \n \n \n \n Spinner dolphins in a remote Hawaiian atoll: social grouping and population structure.\n \n \n \n \n\n\n \n Karczmarski, L.; Wursig, B.; Gailey, G.; Larson, K. W.; and Vanderlip, C.\n\n\n \n\n\n\n Behavioral Ecology, 16(4): 675–685. 2005.\n 00139\n\n\n\n
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\n\n\n\n@article{karczmarski_spinner_2005,\n\ttitle = {Spinner dolphins in a remote {Hawaiian} atoll: social grouping and population structure},\n\tvolume = {16},\n\tissn = {1045-2249},\n\turl = {http://beheco.oxfordjournals.org/content/16/4/675.short},\n\tdoi = {10.1093/beheco/ari028},\n\tnumber = {4},\n\tjournal = {Behavioral Ecology},\n\tauthor = {Karczmarski, Leszek and Wursig, Bernd and Gailey, Glenn and Larson, Keith W. and Vanderlip, Cynthia},\n\tyear = {2005},\n\tnote = {00139},\n\tkeywords = {\\#nosource, Hawaii, Midway Atoll, Spinner dolphin Stenella longirostris, connectivity, geographic insularity, geographic insularity/connectivity, group dynamics, social evolution, social structure},\n\tpages = {675--685},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Contributions of internal and external sources to the CO2 emission from a subarctic lake.\n \n \n \n \n\n\n \n Åberg, J.; Jansson, M.; and Jonsson, A.\n\n\n \n\n\n\n SIL Proceedings, 1922-2010, 29(2): 577–579. September 2005.\n 00004\n\n\n\n
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\n\n\n\n@article{aberg_contributions_2005,\n\ttitle = {Contributions of internal and external sources to the {CO2} emission from a subarctic lake},\n\tvolume = {29},\n\tissn = {0368-0770},\n\turl = {https://doi.org/10.1080/03680770.2005.11902742},\n\tdoi = {10.1080/03680770.2005.11902742},\n\tnumber = {2},\n\turldate = {2018-06-11},\n\tjournal = {SIL Proceedings, 1922-2010},\n\tauthor = {Åberg, Jan and Jansson, Mats and Jonsson, Anders},\n\tmonth = sep,\n\tyear = {2005},\n\tnote = {00004},\n\tkeywords = {\\#nosource, DIC, DOC, carbon budget, carbon mineralization, respiration},\n\tpages = {577--579},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Winter browsing of moose on two different willow species: food selection in relation to plant chemistry and plant response.\n \n \n \n \n\n\n \n Stolter, C.; Ball, J. P; Julkunen-Tiitto, R.; Lieberei, R.; and Ganzhorn, J. U\n\n\n \n\n\n\n Canadian Journal of Zoology, 83(6): 807–819. June 2005.\n 00060\n\n\n\n
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\n\n\n@article{stolter_winter_2005,\n\ttitle = {Winter browsing of moose on two different willow species: food selection in relation to plant chemistry and plant response},\n\tvolume = {83},\n\tissn = {0008-4301},\n\tshorttitle = {Winter browsing of moose on two different willow species},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/z05-077},\n\tdoi = {10.1139/z05-077},\n\tabstract = {We investigated the selection criteria of moose, Alces alces (L., 1758), feeding on two willow species, Salix phylicifolia L. and Salix myrsinifolia Salisb., and whether these willows respond chemically. We correlated winter twig browsing with the concentrations of primary and secondary plant compounds in twigs and new leaves. Furthermore, we investigated 12 specific phenolics in twigs of S. phylicifolia. During winter, moose browsed twigs with low concentrations of phenolic compounds. Additionally, we found significant negative correlations between browsing and the concentration of 7 of the 12 specific phenolic compounds in S. phylicifolia. Most importantly, even though ours was a field study and had many potential sources of variation, a multivariate analysis revealed that these specific phenolics predicted 47\\% of the variation in moose browsing. The two willows reacted in different chemical ways to moose browsing, but both showed signs of defensive response in early spring and compensation growth in su..., Nous avons étudié les critères de sélection chez des orignaux, Alces alces (L., 1758), qui se nourrissent de deux espèces de saules, Salix phylicifolia L. et Salix myrsinifolia Salisb., et déterminé s'il y a une réponse chimique chez les saules. Il existe une corrélation entre le broutage des ramilles en hiver et les concentrations de métabolites primaires et secondaires dans les ramilles et les nouvelles feuilles. Nous avons, de plus, analysé 12 produits phénolés spécifiques dans les ramilles de S. phylicifolia. Durant l'hiver, les orignaux broutent des ramilles à faibles concentrations de produits phénolés. De plus, il existe des corrélations négatives significatives entre le broutage et les concentrations de 7 des 12 produits phénolés spécifiques chez S. phylicifolia. De façon beaucoup plus significative, bien que notre recherche soit une étude de terrain et qu'elle soit sujette à de nombreuses sources potentielles de variation, une analyse multidimensionnelle montre que ces produits phénolés spécifiqu...},\n\tnumber = {6},\n\turldate = {2018-06-11},\n\tjournal = {Canadian Journal of Zoology},\n\tauthor = {Stolter, Caroline and Ball, John P and Julkunen-Tiitto, Riitta and Lieberei, Reinhard and Ganzhorn, Jörg U},\n\tmonth = jun,\n\tyear = {2005},\n\tnote = {00060},\n\tkeywords = {\\#nosource},\n\tpages = {807--819},\n}\n\n\n\n\n\n We investigated the selection criteria of moose, Alces alces (L., 1758), feeding on two willow species, Salix phylicifolia L. and Salix myrsinifolia Salisb., and whether these willows respond chemically. We correlated winter twig browsing with the concentrations of primary and secondary plant compounds in twigs and new leaves. Furthermore, we investigated 12 specific phenolics in twigs of S. phylicifolia. During winter, moose browsed twigs with low concentrations of phenolic compounds. Additionally, we found significant negative correlations between browsing and the concentration of 7 of the 12 specific phenolic compounds in S. phylicifolia. Most importantly, even though ours was a field study and had many potential sources of variation, a multivariate analysis revealed that these specific phenolics predicted 47% of the variation in moose browsing. The two willows reacted in different chemical ways to moose browsing, but both showed signs of defensive response in early spring and compensation growth in su..., Nous avons étudié les critères de sélection chez des orignaux, Alces alces (L., 1758), qui se nourrissent de deux espèces de saules, Salix phylicifolia L. et Salix myrsinifolia Salisb., et déterminé s'il y a une réponse chimique chez les saules. Il existe une corrélation entre le broutage des ramilles en hiver et les concentrations de métabolites primaires et secondaires dans les ramilles et les nouvelles feuilles. Nous avons, de plus, analysé 12 produits phénolés spécifiques dans les ramilles de S. phylicifolia. Durant l'hiver, les orignaux broutent des ramilles à faibles concentrations de produits phénolés. De plus, il existe des corrélations négatives significatives entre le broutage et les concentrations de 7 des 12 produits phénolés spécifiques chez S. phylicifolia. De façon beaucoup plus significative, bien que notre recherche soit une étude de terrain et qu'elle soit sujette à de nombreuses sources potentielles de variation, une analyse multidimensionnelle montre que ces produits phénolés spécifiqu...\n
\n\n\n\n \n\n \n \n \n \n \n \n Total Organic Carbon (TOC) of Lake Water During the Holocene Inferred from Lake Sediments and Near-infrared Spectroscopy (NIRS) in Eight Lakes from Northern Sweden.\n \n \n \n \n\n\n \n Rosén, P.\n\n\n \n\n\n\n Biogeochemistry, 76(3): 503–516. December 2005.\n 00067\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{rosen_total_2005,\n\ttitle = {Total {Organic} {Carbon} ({TOC}) of {Lake} {Water} {During} the {Holocene} {Inferred} from {Lake} {Sediments} and {Near}-infrared {Spectroscopy} ({NIRS}) in {Eight} {Lakes} from {Northern} {Sweden}},\n\tvolume = {76},\n\tissn = {0168-2563, 1573-515X},\n\turl = {https://link.springer.com/article/10.1007/s10533-005-8829-1},\n\tdoi = {10.1007/s10533-005-8829-1},\n\tabstract = {The aim of this study is to infer past changes in total organic carbon (TOC) content of lake water during the Holocene in eight boreal forest, tree-limit and alpine lakes using a new technique – near-infrared spectroscopy (NIRS). A training set of 100 lakes from northern Sweden covering a TOC gradient from 0.7 to 14.9 mg l−1 was used to establish a relationship between the NIRS signal from surface sediments (0–1 cm) and the TOC content of the water mass. The NIRS model for TOC has a root mean squared error (RMSECV) of calibration of 1.6 mg l−1 (11\\% of the gradient) assessed by internal cross-validation (CV), which yields an R 2 cv of 0.61. The results show that the most dramatic change among the studied lakes occurs in both tree-line lakes around 1000 yrs BP when the TOC content decreases from ca. 7 to 3 mg l−1 at the present, which is probably due to a descending tree-limit. The TOC content in the alpine lakes shows a declining trend throughout most of the Holocene indicating that TOC may be more directly correlated to climate in alpine lakes than forest lakes. All boreal forest lakes show a declining trend in TOC during the past 3000 yrs with the largest amplitude of change occurring in the lake with a connected mire. The results indicate that a change to a warmer and more humid climate can increase the TOC levels in lakes, which in turn may increase the saturation of CO2 in lake waters and the emission of CO2 to the atmosphere.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-06-11},\n\tjournal = {Biogeochemistry},\n\tauthor = {Rosén, Peter},\n\tmonth = dec,\n\tyear = {2005},\n\tnote = {00067},\n\tkeywords = {\\#nosource},\n\tpages = {503--516},\n}\n\n\n\n\n\n The aim of this study is to infer past changes in total organic carbon (TOC) content of lake water during the Holocene in eight boreal forest, tree-limit and alpine lakes using a new technique – near-infrared spectroscopy (NIRS). A training set of 100 lakes from northern Sweden covering a TOC gradient from 0.7 to 14.9 mg l−1 was used to establish a relationship between the NIRS signal from surface sediments (0–1 cm) and the TOC content of the water mass. The NIRS model for TOC has a root mean squared error (RMSECV) of calibration of 1.6 mg l−1 (11% of the gradient) assessed by internal cross-validation (CV), which yields an R 2 cv of 0.61. The results show that the most dramatic change among the studied lakes occurs in both tree-line lakes around 1000 yrs BP when the TOC content decreases from ca. 7 to 3 mg l−1 at the present, which is probably due to a descending tree-limit. The TOC content in the alpine lakes shows a declining trend throughout most of the Holocene indicating that TOC may be more directly correlated to climate in alpine lakes than forest lakes. All boreal forest lakes show a declining trend in TOC during the past 3000 yrs with the largest amplitude of change occurring in the lake with a connected mire. The results indicate that a change to a warmer and more humid climate can increase the TOC levels in lakes, which in turn may increase the saturation of CO2 in lake waters and the emission of CO2 to the atmosphere.\n
\n\n\n\n \n\n \n \n \n \n \n \n Quantitative Calibration of Remote Mountain-Lake Sediments as Climatic Recorders of Air Temperature and Ice-Cover Duration.\n \n \n \n \n\n\n \n Thompson, R.; Price, D.; Cameron, N.; Jones, V.; Bigler, C.; Rosén, P.; Hall, R. I.; Catalan, J.; García, J.; Weckstrom, J.; and Korhola, A.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 37(4): 626–635. November 2005.\n 00041\n\n\n\n
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\n\n\n@article{thompson_quantitative_2005,\n\ttitle = {Quantitative {Calibration} of {Remote} {Mountain}-{Lake} {Sediments} as {Climatic} {Recorders} of {Air} {Temperature} and {Ice}-{Cover} {Duration}},\n\tvolume = {37},\n\tissn = {1523-0430},\n\turl = {http://www.bioone.org/doi/abs/10.1657/1523-0430(2005)037%5B0626:QCORMS%5D2.0.CO;2},\n\tdoi = {10.1657/1523-0430(2005)037[0626:QCORMS]2.0.CO;2},\n\tabstract = {A combination of empirical modeling and a diatom-based transfer function was developed to reconstruct air temperature and ice-cover duration through the study of lake sediments. By using a thermal degree-day modeling approach, ice-cover duration on European mountain and sub-Arctic lakes is found to be very sensitive to temperature change. For example, our model, which incorporates a weather generator, predicts a 100-day shortening in ice-cover duration for a 3°C temperature rise for catchments at elevations of 1500 m in the Southern Alps and the Pyrenees. For the more maritime lakes of Scotland, 30\\% higher sensitivities (130 d per 3°C) are found, whereas lakes in northwest Finland, in a more continental setting, have only half the sensitivity (50 d per 3°C). A pan-European data set of the species abundance of 252 diatom taxa in 459 mountain and sub-Arctic lakes has been compiled and taxonomically harmonized. Transfer functions were created that relate both seasonal air temperature and ice-cover duration to diatom species composition on the basis of a weighted averaging–partial least squares (WA-PLS) approach. Cross validation was used to test the transfer functions. For ice-cover duration the pan-European data set yields an R-squared value of 0.73, a jack-knifed R-squared value of 0.58, and a residual-mean-square error of prediction (RMSEP) of 23 days. A regional, northern Fennoscandian transect (151 lakes, 122 taxa) yields a jack-knifed R-squared value of 0.50 and an RMSEP of 9 days. For air temperature the pan-European database displayed greatest skill when reconstructing winter or spring temperatures. This result contrasts with the summer temperatures normally studied when using local elevation gradients. The northern Fennoscandian transect has a remarkably low winter RMSEP of 0.73°C.},\n\tnumber = {4},\n\turldate = {2018-06-11},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Thompson, R. and Price, D. and Cameron, N. and Jones, V. and Bigler, C. and Rosén, P. and Hall, R. I. and Catalan, J. and García, J. and Weckstrom, J. and Korhola, A.},\n\tmonth = nov,\n\tyear = {2005},\n\tnote = {00041},\n\tkeywords = {\\#nosource},\n\tpages = {626--635},\n}\n\n\n\n\n\n A combination of empirical modeling and a diatom-based transfer function was developed to reconstruct air temperature and ice-cover duration through the study of lake sediments. By using a thermal degree-day modeling approach, ice-cover duration on European mountain and sub-Arctic lakes is found to be very sensitive to temperature change. For example, our model, which incorporates a weather generator, predicts a 100-day shortening in ice-cover duration for a 3°C temperature rise for catchments at elevations of 1500 m in the Southern Alps and the Pyrenees. For the more maritime lakes of Scotland, 30% higher sensitivities (130 d per 3°C) are found, whereas lakes in northwest Finland, in a more continental setting, have only half the sensitivity (50 d per 3°C). A pan-European data set of the species abundance of 252 diatom taxa in 459 mountain and sub-Arctic lakes has been compiled and taxonomically harmonized. Transfer functions were created that relate both seasonal air temperature and ice-cover duration to diatom species composition on the basis of a weighted averaging–partial least squares (WA-PLS) approach. Cross validation was used to test the transfer functions. For ice-cover duration the pan-European data set yields an R-squared value of 0.73, a jack-knifed R-squared value of 0.58, and a residual-mean-square error of prediction (RMSEP) of 23 days. A regional, northern Fennoscandian transect (151 lakes, 122 taxa) yields a jack-knifed R-squared value of 0.50 and an RMSEP of 9 days. For air temperature the pan-European database displayed greatest skill when reconstructing winter or spring temperatures. This result contrasts with the summer temperatures normally studied when using local elevation gradients. The northern Fennoscandian transect has a remarkably low winter RMSEP of 0.73°C.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of reindeer density on vascular plant diversity on North Scandinavian mountains.\n \n \n \n \n\n\n \n Olofsson, J.; and Oksanen, L.\n\n\n \n\n\n\n Rangifer, 25(1): 5–18. April 2005.\n 00043\n\n\n\n
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\n\n\n@article{olofsson_effects_2005,\n\ttitle = {Effects of reindeer density on vascular plant diversity on {North} {Scandinavian} mountains},\n\tvolume = {25},\n\tcopyright = {Copyright (c) 2015 Johan Olofsson, Lauri Oksanen},\n\tissn = {1890-6729},\n\turl = {http://septentrio.uit.no/index.php/rangifer/article/view/332},\n\tdoi = {10.7557/2.25.1.332},\n\tabstract = {We studied the effects of reindeer grazing on species richness and diversity of vascular plants on dolomite influenced low alpine sites in the species rich northern part of the Scandes using 8 sites with different reindeer densities. Two sites were situated inside Malla Strict Nature Reserve, where reindeer grazing have been totally prohibited since 1981, and strongly restricted since 1950s. The six other sites were located in other species rich hotspot sites standardized to be as similar to the dolomite-influenced sites in Malla Strict Reserve as possible but varying in reindeer densities commonly found in the Fennoscandian mountain chain. Each site with a habitat complex especially rich in rare vascular plants (the Dryas heath – low herb meadow complex) was systematically sampled in four plots of 2 m x 10 m. The plots were divided to 20 squares of 1 m x 1 m, and complete species lists of vascular plants were compiled for each of the squares. The first DCA (detrended correspondence analysis) axis was strongly related to an index of reindeer grazing, indicating that grazing has a strong impact on the composition of the vegetation. None of the characteristics indices of biodiversity (species richness, evenness or Shannon-Wiener H’) was correlated with reindeer density. The local abundances of categories consisting of relatively rare plants (Ca favored plants and red listed plants of Finland) showed significant, positive correlation with the intensity of reindeer grazing. We conclude that even though the density of reindeer has no influence on the total species richness or diversity of vascular plants, reindeer may still be important for regional biodiversity as it seems to favour rare and threatened plants. Moreover, our results imply that standard diversity indices may have limited value in the context of conservation biology, as these indices are equally influenced by rarities and by trivial species.Abstract in Swedish / Sammandrag: Vi studerade hur renbete påverkar kärlväxtflorans artrikedom och diversitet på dolomitpåverkade lågalpina lokaler i de artrikaste delarna av norra Fennoskandien. Vi inventerade 8 lokaler med olika rentätheter. Två lokaler ligger inom Malla Nationalpark, där renar har varit förbjudna sedan 1981 och starkt begränsade sedan 1950-talet. De sex andra lokalerna ligger i andra artrika områden med samma dolomitdominerade berggrund, men är betade av renar. Rentätheterna vid de studerade lokalerna varierar från helt obefintligt till bland de högsta rentätheter man kan finna i Fennoskandien. Inventeringen utfördes genom att systematiskt undersöka fyra 2 m x 10 m stora ytor i varje lokal i en habitattyp som är speciellt rik i ovanliga kärlväxter (fjällsippehed-lågörtsäng komplex). Varje yta delades upp i 20 småytor (1 m x 1 m), och en total artlista upprättades för var och en av dessa småytor. Den första axeln i DCA (detrended correspondence analyses) analysen korrelerade med rentätheten. Det visar att renar påverkar sammansättningen av växtsamhället. Ingen av de vanliga måtten på biodiversitet (artrikedom eller Shannon-Wiener diversitetsindex) var korrelerade med rentätheten. Trots detta, var tätheterna av Ca-gynnade växter och arter rödlistade i Finland positivt korrelerade med rentätheten. Trots att renarna inte påverkade totala artrikedommen, kan de vara betydelsefulla för regionala biodiversiteten eftersom de gynnar ovanliga och hotade arter. De vanliga måtten på biodiversitet har begränsat värde för bevarandebiologiska frågeställningar, eftersom de är lika känsliga för ovanliga och vanliga arter.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Rangifer},\n\tauthor = {Olofsson, Johan and Oksanen, Lauri},\n\tmonth = apr,\n\tyear = {2005},\n\tnote = {00043},\n\tkeywords = {\\#nosource, Arctic, Rangifer tarandus, alpine, disturbance, diversity, ecology, grazing, vascular plants},\n\tpages = {5--18},\n}\n\n\n\n\n\n We studied the effects of reindeer grazing on species richness and diversity of vascular plants on dolomite influenced low alpine sites in the species rich northern part of the Scandes using 8 sites with different reindeer densities. Two sites were situated inside Malla Strict Nature Reserve, where reindeer grazing have been totally prohibited since 1981, and strongly restricted since 1950s. The six other sites were located in other species rich hotspot sites standardized to be as similar to the dolomite-influenced sites in Malla Strict Reserve as possible but varying in reindeer densities commonly found in the Fennoscandian mountain chain. Each site with a habitat complex especially rich in rare vascular plants (the Dryas heath – low herb meadow complex) was systematically sampled in four plots of 2 m x 10 m. The plots were divided to 20 squares of 1 m x 1 m, and complete species lists of vascular plants were compiled for each of the squares. The first DCA (detrended correspondence analysis) axis was strongly related to an index of reindeer grazing, indicating that grazing has a strong impact on the composition of the vegetation. None of the characteristics indices of biodiversity (species richness, evenness or Shannon-Wiener H’) was correlated with reindeer density. The local abundances of categories consisting of relatively rare plants (Ca favored plants and red listed plants of Finland) showed significant, positive correlation with the intensity of reindeer grazing. We conclude that even though the density of reindeer has no influence on the total species richness or diversity of vascular plants, reindeer may still be important for regional biodiversity as it seems to favour rare and threatened plants. Moreover, our results imply that standard diversity indices may have limited value in the context of conservation biology, as these indices are equally influenced by rarities and by trivial species.Abstract in Swedish / Sammandrag: Vi studerade hur renbete påverkar kärlväxtflorans artrikedom och diversitet på dolomitpåverkade lågalpina lokaler i de artrikaste delarna av norra Fennoskandien. Vi inventerade 8 lokaler med olika rentätheter. Två lokaler ligger inom Malla Nationalpark, där renar har varit förbjudna sedan 1981 och starkt begränsade sedan 1950-talet. De sex andra lokalerna ligger i andra artrika områden med samma dolomitdominerade berggrund, men är betade av renar. Rentätheterna vid de studerade lokalerna varierar från helt obefintligt till bland de högsta rentätheter man kan finna i Fennoskandien. Inventeringen utfördes genom att systematiskt undersöka fyra 2 m x 10 m stora ytor i varje lokal i en habitattyp som är speciellt rik i ovanliga kärlväxter (fjällsippehed-lågörtsäng komplex). Varje yta delades upp i 20 småytor (1 m x 1 m), och en total artlista upprättades för var och en av dessa småytor. Den första axeln i DCA (detrended correspondence analyses) analysen korrelerade med rentätheten. Det visar att renar påverkar sammansättningen av växtsamhället. Ingen av de vanliga måtten på biodiversitet (artrikedom eller Shannon-Wiener diversitetsindex) var korrelerade med rentätheten. Trots detta, var tätheterna av Ca-gynnade växter och arter rödlistade i Finland positivt korrelerade med rentätheten. Trots att renarna inte påverkade totala artrikedommen, kan de vara betydelsefulla för regionala biodiversiteten eftersom de gynnar ovanliga och hotade arter. De vanliga måtten på biodiversitet har begränsat värde för bevarandebiologiska frågeställningar, eftersom de är lika känsliga för ovanliga och vanliga arter.\n
\n\n\n\n \n\n \n \n \n \n \n \n Are growth forms consistent predictors of leaf litter quality and decomposability across peatlands along a latitudinal gradient?.\n \n \n \n \n\n\n \n Dorrepaal, E.; Cornelissen, J. H.; Aerts, R.; Wallén, B.; and Van Logtestijn, R. S.\n\n\n \n\n\n\n Journal of Ecology, 93(4): 817–828. August 2005.\n \n\n\n\n
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\n\n\n@article{dorrepaal_are_2005,\n\ttitle = {Are growth forms consistent predictors of leaf litter quality and decomposability across peatlands along a latitudinal gradient?},\n\tvolume = {93},\n\tissn = {1365-2745},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2005.01024.x/abstract},\n\tdoi = {10.1111/j.1365-2745.2005.01024.x},\n\tabstract = {*\n1\nPlant growth forms are widely used to predict the effects of environmental changes, such as climate warming and increased nitrogen deposition, on plant communities, and the consequences of species shifts for carbon and nutrient cycling. We investigated whether the relationship between growth forms and patterns in litter quality and decomposition are independent of environmental conditions and whether growth forms are as good as litter chemistry at predicting decomposability.\n\n\n*\n2\nWe used a natural, latitudinal gradient in NW Europe as a spatial analogue for future increases in temperature and nitrogen availability. Our screening of 70 species typical of Sphagnum-dominated peatlands showed that leaf litters of Sphagnum mosses, evergreen and deciduous shrubs, graminoids and forbs differed significantly in litter chemistry and that the ranking of the growth forms was independent of the region for all litter chemistry variables. Differences among growth forms were usually larger than differences related to the environmental gradient.\n\n\n*\n3\nAfter 8 and 20 months incubation in outdoor, Sphagnum-based decomposition beds, growth forms generally differed in decomposability, but these patterns varied with latitude. Sphagnum litters decomposed slower than other litters in all regions, again explaining its high representation in organic deposits of peatlands. Forb litters generally decomposed fastest, while the differences among the other growth forms were small, particularly at higher latitudes.\n\n\n*\n4\nMultiple regression analyses showed that growth forms were better at predicting leaf litter decomposition than chemical variables in warm-temperate peatlands with a high N-load, but less so in the subarctic, low-N region.\n\n\n*\n5\nOur results indicate that environmental changes may be less important in determining ecosystem leaf litter chemistry directly than are their indirect effects through changes in the relative abundance of growth forms. However, climatic and nutritional constraints in high-latitude peatlands promote convergence towards nutrient-efficient plant traits, resulting in similar decomposition rates of vascular growth forms despite differences in litter chemistry. The usefulness of the growth-form concept in predicting plant community controls on ecosystem functioning is therefore somewhat limited.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-08},\n\tjournal = {Journal of Ecology},\n\tauthor = {Dorrepaal, Ellen and Cornelissen, Johannes H.c. and Aerts, Rien and Wallén, Bo and Van Logtestijn, Richard S.p.},\n\tmonth = aug,\n\tyear = {2005},\n\tkeywords = {\\#nosource, Decomposition, Sphagnum, climate change, environmental gradient, high latitude, leaf litter, litter chemistry, nitrogen deposition, peatlands, plant functional types},\n\tpages = {817--828},\n}\n\n\n\n\n\n * 1 Plant growth forms are widely used to predict the effects of environmental changes, such as climate warming and increased nitrogen deposition, on plant communities, and the consequences of species shifts for carbon and nutrient cycling. We investigated whether the relationship between growth forms and patterns in litter quality and decomposition are independent of environmental conditions and whether growth forms are as good as litter chemistry at predicting decomposability. * 2 We used a natural, latitudinal gradient in NW Europe as a spatial analogue for future increases in temperature and nitrogen availability. Our screening of 70 species typical of Sphagnum-dominated peatlands showed that leaf litters of Sphagnum mosses, evergreen and deciduous shrubs, graminoids and forbs differed significantly in litter chemistry and that the ranking of the growth forms was independent of the region for all litter chemistry variables. Differences among growth forms were usually larger than differences related to the environmental gradient. * 3 After 8 and 20 months incubation in outdoor, Sphagnum-based decomposition beds, growth forms generally differed in decomposability, but these patterns varied with latitude. Sphagnum litters decomposed slower than other litters in all regions, again explaining its high representation in organic deposits of peatlands. Forb litters generally decomposed fastest, while the differences among the other growth forms were small, particularly at higher latitudes. * 4 Multiple regression analyses showed that growth forms were better at predicting leaf litter decomposition than chemical variables in warm-temperate peatlands with a high N-load, but less so in the subarctic, low-N region. * 5 Our results indicate that environmental changes may be less important in determining ecosystem leaf litter chemistry directly than are their indirect effects through changes in the relative abundance of growth forms. However, climatic and nutritional constraints in high-latitude peatlands promote convergence towards nutrient-efficient plant traits, resulting in similar decomposition rates of vascular growth forms despite differences in litter chemistry. The usefulness of the growth-form concept in predicting plant community controls on ecosystem functioning is therefore somewhat limited.\n
\n\n\n\n \n\n \n \n \n \n \n \n Littoral energy mobilization dominates energy supply for top consumers in subarctic lakes.\n \n \n \n \n\n\n \n Karlsson, J.; and Byström, P.\n\n\n \n\n\n\n Limnology and Oceanography, 50(2): 538–543. March 2005.\n 00098\n\n\n\n
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\n\n\n@article{karlsson_littoral_2005,\n\ttitle = {Littoral energy mobilization dominates energy supply for top consumers in subarctic lakes},\n\tvolume = {50},\n\tissn = {1939-5590},\n\turl = {http://onlinelibrary.wiley.com/doi/10.4319/lo.2005.50.2.0538/abstract},\n\tdoi = {10.4319/lo.2005.50.2.0538},\n\tabstract = {We used stable carbon (δ13C) and nitrogen (δ15N) isotopes to assess the energy sources supporting the top consumer (Arctic char, Salvelinus alpinus) in nine subarctic lakes in northern Sweden. The δ13C of littoral (epipelic algae) and pelagic (bacterioplankton and phytoplankton) energy sources were clearly separated in the lakes, as reflected in habitat-specific consumers (zoobenthos, zooplankton). Char were enriched in 13C compared with pelagic energy sources and prey and isotopically more similar to littoral energy sources and prey. The contribution of littoral energy sources to char body carbon was estimated to range between 62\\% and 94\\% among the lakes. The reliance on littoral energy sources was independent of char size and did not change when char coexisted with a small-sized prey fish (nine-spined stickleback, Pungitus pungitus). The strong reliance of top consumers in subarctic lakes on littoral energy sources may be due to the higher energy mobilization and larger sizes of primary consumers in littoral than in pelagic habitats.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-06},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Karlsson, Jan and Byström, Pär},\n\tmonth = mar,\n\tyear = {2005},\n\tnote = {00098},\n\tkeywords = {\\#nosource, Algae, allochthonous organic-carbon, clearwater, delta-c-13, food webs, models, populations, predation, stable-isotope analysis, zooplankton},\n\tpages = {538--543},\n}\n\n\n\n\n\n We used stable carbon (δ13C) and nitrogen (δ15N) isotopes to assess the energy sources supporting the top consumer (Arctic char, Salvelinus alpinus) in nine subarctic lakes in northern Sweden. The δ13C of littoral (epipelic algae) and pelagic (bacterioplankton and phytoplankton) energy sources were clearly separated in the lakes, as reflected in habitat-specific consumers (zoobenthos, zooplankton). Char were enriched in 13C compared with pelagic energy sources and prey and isotopically more similar to littoral energy sources and prey. The contribution of littoral energy sources to char body carbon was estimated to range between 62% and 94% among the lakes. The reliance on littoral energy sources was independent of char size and did not change when char coexisted with a small-sized prey fish (nine-spined stickleback, Pungitus pungitus). The strong reliance of top consumers in subarctic lakes on littoral energy sources may be due to the higher energy mobilization and larger sizes of primary consumers in littoral than in pelagic habitats.\n
\n\n\n\n \n\n \n \n \n \n \n Effects of mammalian herbivores on revegetation of disturbed areas in the forest-tundra ecotone in northern Fennoscandia.\n \n \n \n\n\n \n Olofsson, J.; Hulme, P. E.; Oksanen, L.; and Suominen, O.\n\n\n \n\n\n\n Landscape Ecology, 20(3): 351–359. April 2005.\n \n\n\n\n
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\n\n\n@article{olofsson_effects_2005,\n\ttitle = {Effects of mammalian herbivores on revegetation of disturbed areas in the forest-tundra ecotone in northern {Fennoscandia}},\n\tvolume = {20},\n\tissn = {0921-2973},\n\tdoi = {10.1007/s10980-005-3166-2},\n\tabstract = {Herbivores influence the structure of plant communities in arctic-alpine ecosystems. However, little is known of the effect of herbivores on plant colonisation following disturbance, and on its variability depending on the identity of herbivores and the characteristics of the habitats. To quantify the role of large and small vertebrate herbivores, we established exclosures of two different mesh sizes around disturbed subplots in forest and nearby tundra habitats in four contrasting locations in the forest-tundra ecotone in northernmost Sweden and Norway. The study revealed that herbivores influenced the abundance but not the species composition of regenerating vegetation. Gaps were colonised by the dominant species in the surrounding vegetation. The only exception to this expectation was Empetrum nigrum, which failed to colonise gaps even though it dominated undisturbed vegetation. Significant effects of herbivory were only detected when both small and large herbivores were excluded. Herbivores decreased the abundance of three of the most common species Vaccinium myrtillus, Vaccinium vitis idaea, and Deschampsia flexuosa. The effect of herbivory on the abundance of these three species did not differ between habitats and locations. However, the composition of the regenerating vegetation differed between habitats and locations. The disturbance treatment increased the species richness on the scale of plots, habitats, and sites. However, on the scale of whole locations, all species found in disturbed areas were also found in undisturbed areas, suggesting that the natural disturbance regime in arctic landscapes is high enough to sustain colonising species.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Landscape Ecology},\n\tauthor = {Olofsson, J. and Hulme, P. E. and Oksanen, L. and Suominen, O.},\n\tmonth = apr,\n\tyear = {2005},\n\tkeywords = {\\#nosource, Norwegian lemming, Spatial heterogeneity, disturbance, ecosystem, empetrum-hermaphroditum, gap, germination, grassland plants, grazed salt-marsh, grey-sided vole, herbivory, plant-communities, reindeer, responses, seedling establishment, species richness, vertebrate herbivores},\n\tpages = {351--359},\n}\n\n\n\n\n\n Herbivores influence the structure of plant communities in arctic-alpine ecosystems. However, little is known of the effect of herbivores on plant colonisation following disturbance, and on its variability depending on the identity of herbivores and the characteristics of the habitats. To quantify the role of large and small vertebrate herbivores, we established exclosures of two different mesh sizes around disturbed subplots in forest and nearby tundra habitats in four contrasting locations in the forest-tundra ecotone in northernmost Sweden and Norway. The study revealed that herbivores influenced the abundance but not the species composition of regenerating vegetation. Gaps were colonised by the dominant species in the surrounding vegetation. The only exception to this expectation was Empetrum nigrum, which failed to colonise gaps even though it dominated undisturbed vegetation. Significant effects of herbivory were only detected when both small and large herbivores were excluded. Herbivores decreased the abundance of three of the most common species Vaccinium myrtillus, Vaccinium vitis idaea, and Deschampsia flexuosa. The effect of herbivory on the abundance of these three species did not differ between habitats and locations. However, the composition of the regenerating vegetation differed between habitats and locations. The disturbance treatment increased the species richness on the scale of plots, habitats, and sites. However, on the scale of whole locations, all species found in disturbed areas were also found in undisturbed areas, suggesting that the natural disturbance regime in arctic landscapes is high enough to sustain colonising species.\n
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\n \n \n\n \n \n \n \n \n Age-dependent climate sensitivity of Pinus sylvestris L. in the central Scandinavian Mountains.\n \n \n \n\n\n \n Linderholm, H. W; and Linderholm, K.\n\n\n \n\n\n\n Boreal Environment Research, 9: 11. 2004.\n 00040\n\n\n\n
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\n\n\n\n@article{linderholm_age-dependent_2004,\n\ttitle = {Age-dependent climate sensitivity of {Pinus} sylvestris {L}. in the central {Scandinavian} {Mountains}},\n\tvolume = {9},\n\tissn = {1239-6095},\n\tlanguage = {en},\n\tjournal = {Boreal Environment Research},\n\tauthor = {Linderholm, Hans W and Linderholm, Karin},\n\tyear = {2004},\n\tnote = {00040},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {11},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n δ15N of zooplankton species in subarctic lakes in northern Sweden: effects of diet and trophic fractionation.\n \n \n \n \n\n\n \n Karlsson, J.; Jonsson, A.; Meili, M.; and Jansson, M.\n\n\n \n\n\n\n Freshwater Biology, 49(5): 526–534. May 2004.\n \n\n\n\n
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\n\n\n@article{karlsson_15n_2004,\n\ttitle = {δ{15N} of zooplankton species in subarctic lakes in northern {Sweden}: effects of diet and trophic fractionation},\n\tvolume = {49},\n\tissn = {1365-2427},\n\tshorttitle = {δ{15N} of zooplankton species in subarctic lakes in northern {Sweden}},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2427.2004.01208.x/abstract},\n\tdoi = {10.1111/j.1365-2427.2004.01208.x},\n\tabstract = {1. To assess the use of stable nitrogen isotopes (δ15N) for reconstructing trophic relationships in planktonic food webs, crustacean zooplankton species and pelagic dissolved and particulate matter were analysed in 14 subarctic lakes in northern Sweden. The lakes are situated along an altitudinal gradient and show a substantial variation in nutrient content and energy mobilization by bacterioplankton and phytoplankton. 2. The δ15N of dissolved and particulate matter was comparatively low, suggesting efficient N recycling and low losses of depleted N from the pelagic zone of these unproductive lakes. 3. Copepods had a systematically higher δ15N than cladocerans, with an average difference of 3.1–4.9‰ within lakes, implying different trophic positions of the two groups. Comparisons of nitrogen pools and energy fluxes suggest that the low cladoceran δ15N was a result of feeding on bacteria. 4. The difference in δ15N between copepods and cladocerans declined with decreasing bacterioplankton production among lakes, due either to increasing trophic isotope fractionation or decreasing relative importance of bacteria in the diet of cladocerans.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-06},\n\tjournal = {Freshwater Biology},\n\tauthor = {Karlsson, J. and Jonsson, A. and Meili, M. and Jansson, M.},\n\tmonth = may,\n\tyear = {2004},\n\tkeywords = {\\#nosource, bacterioplankton, food web, isotopic fractionation, phytoplankton, trophic position},\n\tpages = {526--534},\n}\n\n\n\n\n\n 1. To assess the use of stable nitrogen isotopes (δ15N) for reconstructing trophic relationships in planktonic food webs, crustacean zooplankton species and pelagic dissolved and particulate matter were analysed in 14 subarctic lakes in northern Sweden. The lakes are situated along an altitudinal gradient and show a substantial variation in nutrient content and energy mobilization by bacterioplankton and phytoplankton. 2. The δ15N of dissolved and particulate matter was comparatively low, suggesting efficient N recycling and low losses of depleted N from the pelagic zone of these unproductive lakes. 3. Copepods had a systematically higher δ15N than cladocerans, with an average difference of 3.1–4.9‰ within lakes, implying different trophic positions of the two groups. Comparisons of nitrogen pools and energy fluxes suggest that the low cladoceran δ15N was a result of feeding on bacteria. 4. The difference in δ15N between copepods and cladocerans declined with decreasing bacterioplankton production among lakes, due either to increasing trophic isotope fractionation or decreasing relative importance of bacteria in the diet of cladocerans.\n
\n\n\n\n \n\n \n \n \n \n \n \n Holocene temperature estimates and chironomid community composition in the Abisko Valley, northern Sweden.\n \n \n \n \n\n\n \n Larocque, I.; and Hall, R. I.\n\n\n \n\n\n\n Quaternary Science Reviews, 23(23–24): 2453–2465. December 2004.\n \n\n\n\n
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\n\n\n@article{larocque_holocene_2004,\n\ttitle = {Holocene temperature estimates and chironomid community composition in the {Abisko} {Valley}, northern {Sweden}},\n\tvolume = {23},\n\tissn = {0277-3791},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0277379104001301},\n\tdoi = {10.1016/j.quascirev.2004.04.006},\n\tabstract = {Multi-proxy paleoenvironmental reconstructions are useful to determine the various factors affecting the biological communities of a lake, but to assess if changes in community composition of one indicator organism accurately reconstructs climatic changes through time, it may be more useful to compare temperature reconstructions using the same indicator in several lakes. Here, we compare reconstructions of mean July air temperature using chironomid-based transfer functions from Holocene records at three nearby lakes in the Abisko Valley of northern Sweden to assess if chironomids can be used as indicators of regional temperature changes. The three study lakes experience the same regional climatic conditions, but are located along gradients of elevation (348–999 m a.s.l), temperature (8.1–12°C) and terrestrial vegetation (coniferous to alpine). Chironomid-temperature reconstructions from the three sites indicate a general pattern of temperature decrease (1.5–2.4°C) during the Holocene, consistent with decreases observed from analyses of other proxies in this area, and from other alpine regions in Europe and North America. Similarities between these reconstructions suggest that chironomids can adequately record general patterns of temperature changes through the Holocene, although effects of site-specific factors such as variations in lake water pH can cause deviations in inferred temperature among sites during some periods.},\n\tnumber = {23–24},\n\turldate = {2017-02-07},\n\tjournal = {Quaternary Science Reviews},\n\tauthor = {Larocque, I. and Hall, R. I.},\n\tmonth = dec,\n\tyear = {2004},\n\tkeywords = {\\#nosource},\n\tpages = {2453--2465},\n}\n\n\n\n\n\n Multi-proxy paleoenvironmental reconstructions are useful to determine the various factors affecting the biological communities of a lake, but to assess if changes in community composition of one indicator organism accurately reconstructs climatic changes through time, it may be more useful to compare temperature reconstructions using the same indicator in several lakes. Here, we compare reconstructions of mean July air temperature using chironomid-based transfer functions from Holocene records at three nearby lakes in the Abisko Valley of northern Sweden to assess if chironomids can be used as indicators of regional temperature changes. The three study lakes experience the same regional climatic conditions, but are located along gradients of elevation (348–999 m a.s.l), temperature (8.1–12°C) and terrestrial vegetation (coniferous to alpine). Chironomid-temperature reconstructions from the three sites indicate a general pattern of temperature decrease (1.5–2.4°C) during the Holocene, consistent with decreases observed from analyses of other proxies in this area, and from other alpine regions in Europe and North America. Similarities between these reconstructions suggest that chironomids can adequately record general patterns of temperature changes through the Holocene, although effects of site-specific factors such as variations in lake water pH can cause deviations in inferred temperature among sites during some periods.\n
\n\n\n\n \n\n \n \n \n \n \n \n Modelling biomass and leaf area index in a sub-arctic Scandinavian mountain area.\n \n \n \n \n\n\n \n Dahlberg, U.; Berge, T. W.; Petersson, H.; and Vencatasawmy, C. P.\n\n\n \n\n\n\n Scandinavian Journal of Forest Research, 19(1): 60–71. February 2004.\n 00038\n\n\n\n
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\n\n\n@article{dahlberg_modelling_2004,\n\ttitle = {Modelling biomass and leaf area index in a sub-arctic {Scandinavian} mountain area},\n\tvolume = {19},\n\tissn = {0282-7581},\n\turl = {https://doi.org/10.1080/02827580310019266},\n\tdoi = {10.1080/02827580310019266},\n\tabstract = {Estimates of biomass and leaf area index (LAI) are important variables in ecological and climate models. However, very little is known about the biomass and LAI of the vegetation in the Scandinavian mountain area. In this study, extensive field data consisting of diameter at breast height for 13 000 trees and height for 550 trees were collected. Furthermore, biomass and leaf area (LA) measurements for 46 mountain birch trees [Betula pubescens ssp. czerepanovii (Orlowa) Hämet-Ahti] and biomass and LA measurements for shrubs (e.g. Salix spp., Betula nana) at 36 sample plots were carried out. Multiplicative linear models for trees were fitted to tree biomass and LA measurements using basal area at breast height, height, crown diameter and diameter at stump height as explanatory variables. Additive linear models were fitted to shrub biomass and LAI measurements using coverage of shrubs, topographic variables and soil type as explanatory variables. The functions were then used to predict the biomass and LAI for trees and shrubs for the entire test area, which covers an area of 84 km2 and is located at latitude 68° N. The mean total biomass estimates were 27 493 kg ha−1 for the forest and 7650 kg ha−1 for snow-protected heath and meadow vegetation. The LAIs were 2.06 and 0.52, respectively. For monitoring biomass and LAI in the Scandinavian mountain area, the functions could also be applied to data from traditional field-based inventories and the estimates might further be improved by combining the estimates from the test area with auxiliary information such as remote sensing images.},\n\tnumber = {1},\n\turldate = {2018-06-11},\n\tjournal = {Scandinavian Journal of Forest Research},\n\tauthor = {Dahlberg, Ulrika and Berge, Therese W. and Petersson, Hans and Vencatasawmy, Coomaren P.},\n\tmonth = feb,\n\tyear = {2004},\n\tnote = {00038},\n\tkeywords = {\\#nosource, Abisko, Betula pubescens ssp. czerepanovii, allometric relationship, ground vegetation, mountain birch, shrub layer},\n\tpages = {60--71},\n}\n\n\n\n\n\n Estimates of biomass and leaf area index (LAI) are important variables in ecological and climate models. However, very little is known about the biomass and LAI of the vegetation in the Scandinavian mountain area. In this study, extensive field data consisting of diameter at breast height for 13 000 trees and height for 550 trees were collected. Furthermore, biomass and leaf area (LA) measurements for 46 mountain birch trees [Betula pubescens ssp. czerepanovii (Orlowa) Hämet-Ahti] and biomass and LA measurements for shrubs (e.g. Salix spp., Betula nana) at 36 sample plots were carried out. Multiplicative linear models for trees were fitted to tree biomass and LA measurements using basal area at breast height, height, crown diameter and diameter at stump height as explanatory variables. Additive linear models were fitted to shrub biomass and LAI measurements using coverage of shrubs, topographic variables and soil type as explanatory variables. The functions were then used to predict the biomass and LAI for trees and shrubs for the entire test area, which covers an area of 84 km2 and is located at latitude 68° N. The mean total biomass estimates were 27 493 kg ha−1 for the forest and 7650 kg ha−1 for snow-protected heath and meadow vegetation. The LAIs were 2.06 and 0.52, respectively. For monitoring biomass and LAI in the Scandinavian mountain area, the functions could also be applied to data from traditional field-based inventories and the estimates might further be improved by combining the estimates from the test area with auxiliary information such as remote sensing images.\n
\n\n\n\n \n\n \n \n \n \n \n \n Similarities and discrepancies between chironomid- and diatom-inferred temperature reconstructions through the Holocene at Lake 850, northern Sweden.\n \n \n \n \n\n\n \n Larocque, I.; and Bigler, C.\n\n\n \n\n\n\n Quaternary International, 122(1): 109–121. January 2004.\n 00051\n\n\n\n
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\n\n\n@article{larocque_similarities_2004,\n\tseries = {{HIgh} resolution lake sediment records in climate and {Environment} variability studies:{European} lake drilling program},\n\ttitle = {Similarities and discrepancies between chironomid- and diatom-inferred temperature reconstructions through the {Holocene} at {Lake} 850, northern {Sweden}},\n\tvolume = {122},\n\tissn = {1040-6182},\n\turl = {http://www.sciencedirect.com/science/article/pii/S1040618204000448},\n\tdoi = {10.1016/j.quaint.2004.01.033},\n\tabstract = {A quantitative temperature reconstruction using chironomids and diatoms has been attempted from a high elevation lake in northern Sweden (Lake 850). Since 7000 cal. years BP, both chironomids and diatoms recorded similar temperatures (in the range of present-day estimates) but the correspondence between chironomid and diatom-inferred temperatures was highest in the recent Holocene (2500 cal. years BP to the present). Between ca. 9000 and 7000 cal. years BP, inferred temperatures from chironomids were warmer than today (ca. 1–2°C), in accord with other climate reconstruction using pollen, plant macrofossils and oxygen isotope analysis in lakes of northern Scandinavia. In contrast, diatom analysis did not infer warmer temperatures during this period. The insensitivity of diatoms to temperature in Lake 850 between 9000 and 7000 cal. years BP could be attributed to other environmental factors affecting the diatom assemblages through time, especially lake-water pH. Diatom-inferred pH showed a gradual decrease (0.5 pH units) between 9000 and 7000 cal. years BP while it remained more or less constant since 7000 cal. years BP. Changes in lake-water pH acting on diatoms seem to mask the effect of climate, leading to temperature reconstructions that are inaccurate. Ways of disentangling climate and other environmental factors when attempting climate reconstruction should be further investigated.},\n\tnumber = {1},\n\turldate = {2018-06-11},\n\tjournal = {Quaternary International},\n\tauthor = {Larocque, I. and Bigler, C.},\n\tmonth = jan,\n\tyear = {2004},\n\tnote = {00051},\n\tkeywords = {\\#nosource},\n\tpages = {109--121},\n}\n\n\n\n\n\n A quantitative temperature reconstruction using chironomids and diatoms has been attempted from a high elevation lake in northern Sweden (Lake 850). Since 7000 cal. years BP, both chironomids and diatoms recorded similar temperatures (in the range of present-day estimates) but the correspondence between chironomid and diatom-inferred temperatures was highest in the recent Holocene (2500 cal. years BP to the present). Between ca. 9000 and 7000 cal. years BP, inferred temperatures from chironomids were warmer than today (ca. 1–2°C), in accord with other climate reconstruction using pollen, plant macrofossils and oxygen isotope analysis in lakes of northern Scandinavia. In contrast, diatom analysis did not infer warmer temperatures during this period. The insensitivity of diatoms to temperature in Lake 850 between 9000 and 7000 cal. years BP could be attributed to other environmental factors affecting the diatom assemblages through time, especially lake-water pH. Diatom-inferred pH showed a gradual decrease (0.5 pH units) between 9000 and 7000 cal. years BP while it remained more or less constant since 7000 cal. years BP. Changes in lake-water pH acting on diatoms seem to mask the effect of climate, leading to temperature reconstructions that are inaccurate. Ways of disentangling climate and other environmental factors when attempting climate reconstruction should be further investigated.\n
\n\n\n\n \n\n \n \n \n \n \n \n Holocene Climatic Change and Landscape Response at Cathedral Provincial Park, British Columbia, Canada.\n \n \n \n \n\n\n \n Heinrichs, M.; Evans, M.; Hebda, R.; Walker, I.; Palmer, S.; and Rosenberg, S.\n\n\n \n\n\n\n Géographie physique et Quaternaire, 58(1): 123–139. 2004.\n 00003\n\n\n\n
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\n\n\n@article{heinrichs_holocene_2004,\n\ttitle = {Holocene {Climatic} {Change} and {Landscape} {Response} at {Cathedral} {Provincial} {Park}, {British} {Columbia}, {Canada}},\n\tvolume = {58},\n\tissn = {0705-7199, 1492-143X},\n\turl = {http://www.erudit.org/en/journals/gpq/2004-v58-n1-gpq1200/013113ar/abstract/},\n\tdoi = {10.7202/013113ar},\n\tabstract = {Environmental sensitivity to temperature change was established by comparing pollen, plant macrofossils, macroscopic charcoal, and sediment yield data from Lake of the Woods, Cathedral Provincial Park in the Cascade Mountains of southern British Columbia, Canada, to an independent record of midge-inferred paleotemperature. Steppe vegetation with some spruce and fir occurred initially, developing into pine forests in the warm early Holocene. These forests burned often, preventing spruce and fir succession. Once established, the forests retained an Engelmann Spruce-Subalpine Fir character. After 8000 cal BP, in warm but wetter conditions, the forest contained less pine and fires burned less frequently. About 4000 cal BP, cooler temperatures resulted in closure of the Engelmann Spruce-Subalpine Fir forests and a further reduction in fire frequency. Sediment yield results suggest a stable environment throughout the Holocene, likely due to sediment trapping in two upstream lakes. Midge-inferred temperatures correspond closely with a consensus reconstruction of temperatures from southern British Columbia, however Cathedral Provincial Park terrestrial ecosystems were not as sensitive to past climate change when compared to other nearby Engelmann Spruce-Subalpine Fir sites.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-06-11},\n\tjournal = {Géographie physique et Quaternaire},\n\tauthor = {Heinrichs, Markus and Evans, Martin and Hebda, Richard and Walker, Ian and Palmer, Samantha and Rosenberg, Sandra},\n\tyear = {2004},\n\tnote = {00003},\n\tkeywords = {\\#nosource},\n\tpages = {123--139},\n}\n\n\n\n\n\n Environmental sensitivity to temperature change was established by comparing pollen, plant macrofossils, macroscopic charcoal, and sediment yield data from Lake of the Woods, Cathedral Provincial Park in the Cascade Mountains of southern British Columbia, Canada, to an independent record of midge-inferred paleotemperature. Steppe vegetation with some spruce and fir occurred initially, developing into pine forests in the warm early Holocene. These forests burned often, preventing spruce and fir succession. Once established, the forests retained an Engelmann Spruce-Subalpine Fir character. After 8000 cal BP, in warm but wetter conditions, the forest contained less pine and fires burned less frequently. About 4000 cal BP, cooler temperatures resulted in closure of the Engelmann Spruce-Subalpine Fir forests and a further reduction in fire frequency. Sediment yield results suggest a stable environment throughout the Holocene, likely due to sediment trapping in two upstream lakes. Midge-inferred temperatures correspond closely with a consensus reconstruction of temperatures from southern British Columbia, however Cathedral Provincial Park terrestrial ecosystems were not as sensitive to past climate change when compared to other nearby Engelmann Spruce-Subalpine Fir sites.\n
\n\n\n\n \n\n \n \n \n \n \n \n Ecological linkages between aboveground and belowground biota.\n \n \n \n \n\n\n \n Wardle, D. A.; Bardgett, R. D.; Klironomos, J. N.; Setälä, H.; Van Der Putten, W. H.; and Wall, D. H.\n\n\n \n\n\n\n Science, 304(5677): 1629–1633. 2004.\n 02237\n\n\n\n
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\n\n\n@article{wardle_ecological_2004,\n\ttitle = {Ecological linkages between aboveground and belowground biota},\n\tvolume = {304},\n\turl = {http://www.sciencemag.org/content/304/5677/1629.short},\n\tdoi = {10.1126/science.1094875},\n\tabstract = {01771},\n\tnumber = {5677},\n\turldate = {2015-08-18},\n\tjournal = {Science},\n\tauthor = {Wardle, David A. and Bardgett, Richard D. and Klironomos, John N. and Setälä, Heikki and Van Der Putten, Wim H. and Wall, Diana H.},\n\tyear = {2004},\n\tnote = {02237},\n\tkeywords = {\\#nosource},\n\tpages = {1629--1633},\n}\n\n\n\n\n\n 01771\n
\n\n\n\n \n\n \n \n \n \n \n Positive and negative plant-plant interactions in two contrasting arctic-alpine plant communities.\n \n \n \n\n\n \n Olofsson, J.\n\n\n \n\n\n\n Arctic Antarctic and Alpine Research, 36(4): 464–467. November 2004.\n 00044\n\n\n\n
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\n\n\n@article{olofsson_positive_2004,\n\ttitle = {Positive and negative plant-plant interactions in two contrasting arctic-alpine plant communities},\n\tvolume = {36},\n\tissn = {1523-0430},\n\tdoi = {10.1657/1523-0430(2004)036[0464:PANPII]2.0.CO;2},\n\tabstract = {Positive interactions in alpine plant communities have been reported to increase in importance with increasing altitude and exposure. Positive and negative interactions between plants might occur simultaneously, so the net plant-plant interaction is determined by the balance between positive and negative effects. I investigated the relative effect of facilitation and resource competition by surrounding dwarf shrubs on Carex bigelowii in two contrasting arctic-alpine tundra heathlands. Carex bigelowii was positively associated with dwarf shrubs on an exposed mountain ridge but negatively associated with dwarf shrubs on a protected heath. A removal experiment indicated that positive associations at the exposed site are the result of facilitation of C. bigelowii by the dwarf shrub canopy. Our understanding of arctic and alpine plant communities can be enhanced by regarding plant interactions as combinations of positive and negative components.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Arctic Antarctic and Alpine Research},\n\tauthor = {Olofsson, J.},\n\tmonth = nov,\n\tyear = {2004},\n\tnote = {00044},\n\tkeywords = {\\#nosource, Nitrogen, availability, competition intensity, dwarf shrubs, facilitation, field experiments, growth, interspecific competition, mycorrhizal, tundra communities},\n\tpages = {464--467},\n}\n\n\n\n\n\n Positive interactions in alpine plant communities have been reported to increase in importance with increasing altitude and exposure. Positive and negative interactions between plants might occur simultaneously, so the net plant-plant interaction is determined by the balance between positive and negative effects. I investigated the relative effect of facilitation and resource competition by surrounding dwarf shrubs on Carex bigelowii in two contrasting arctic-alpine tundra heathlands. Carex bigelowii was positively associated with dwarf shrubs on an exposed mountain ridge but negatively associated with dwarf shrubs on a protected heath. A removal experiment indicated that positive associations at the exposed site are the result of facilitation of C. bigelowii by the dwarf shrub canopy. Our understanding of arctic and alpine plant communities can be enhanced by regarding plant interactions as combinations of positive and negative components.\n
\n\n\n\n \n\n \n \n \n \n \n Importance of large and small mammalian herbivores for the plant community structure in the forest tundra ecotone.\n \n \n \n\n\n \n Olofsson, J.; Hulme, P. E.; Oksanen, L.; and Suominen, O.\n\n\n \n\n\n\n Oikos, 106(2): 324–334. August 2004.\n 00118\n\n\n\n
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\n\n\n@article{olofsson_importance_2004,\n\ttitle = {Importance of large and small mammalian herbivores for the plant community structure in the forest tundra ecotone},\n\tvolume = {106},\n\tissn = {0030-1299},\n\tdoi = {10.1111/j.0030-1299.2004.13224.x},\n\tabstract = {Both theoretical arguments and empirical evidence suggests that herbivory in general and mammalian winter herbivory in particular is important in arctic-alpine ecosystems. Although knowledge of the effect of herbivores on specific plants and communities is quite extensive, little is known about the relative impact of large and small vertebrate herbivores and how it might vary among different habitats. To address this key issue, we established exclosures with two different mesh sizes in forest and nearby tundra at three different sites in four contrasting locations in the forest-tundra ecotone in northernmost Sweden and Norway. Plant community composition was recorded annually in three permanent plots within each exclosure and an unfenced control. Local densities of vertebrate herbivores were estimated in spring and autumn from 1998 to 2002. Reindeer (Rangifer tarandus) were the most abundant large vertebrate while Norwegian lemmings (Lemmus lemmus) and grey-sided voles (Clethrionomys rufocanus) were the most common small vertebrates. The study reveals that voles and lemmings have larger effects on the vegetation than reindeer in both habitats in all four locations, even though densities of reindeer differ between locations and only two locations experienced lemming peaks during the period of the experiment. The relative abundance of five of the fifteen most common species was significantly influenced by voles and lemmings whereas only a single species was significantly influenced by reindeer. Different analyses give contrasting results on the importance of herbivory in forest versus open heathlands. A principal component analyses revealed that herbivory influenced the vegetation more in open heathlands than in forests. However, an importance index of herbivores did not differ between forest and open heathlands. Moreover, none of the plant species responded differently in the two habitats, when herbivores were removed. Our results suggest that intense and localised selective foraging by small mammals may have a more marked effect on vegetation than transient feeding by reindeer.},\n\tlanguage = {English},\n\tnumber = {2},\n\tjournal = {Oikos},\n\tauthor = {Olofsson, J. and Hulme, P. E. and Oksanen, L. and Suominen, O.},\n\tmonth = aug,\n\tyear = {2004},\n\tnote = {00118},\n\tkeywords = {\\#nosource, abiotic factors, biomass, body-size, finnish lapland, grazed salt-marsh, impact, productivity, reindeer, responses, vegetation},\n\tpages = {324--334},\n}\n\n\n\n\n\n Both theoretical arguments and empirical evidence suggests that herbivory in general and mammalian winter herbivory in particular is important in arctic-alpine ecosystems. Although knowledge of the effect of herbivores on specific plants and communities is quite extensive, little is known about the relative impact of large and small vertebrate herbivores and how it might vary among different habitats. To address this key issue, we established exclosures with two different mesh sizes in forest and nearby tundra at three different sites in four contrasting locations in the forest-tundra ecotone in northernmost Sweden and Norway. Plant community composition was recorded annually in three permanent plots within each exclosure and an unfenced control. Local densities of vertebrate herbivores were estimated in spring and autumn from 1998 to 2002. Reindeer (Rangifer tarandus) were the most abundant large vertebrate while Norwegian lemmings (Lemmus lemmus) and grey-sided voles (Clethrionomys rufocanus) were the most common small vertebrates. The study reveals that voles and lemmings have larger effects on the vegetation than reindeer in both habitats in all four locations, even though densities of reindeer differ between locations and only two locations experienced lemming peaks during the period of the experiment. The relative abundance of five of the fifteen most common species was significantly influenced by voles and lemmings whereas only a single species was significantly influenced by reindeer. Different analyses give contrasting results on the importance of herbivory in forest versus open heathlands. A principal component analyses revealed that herbivory influenced the vegetation more in open heathlands than in forests. However, an importance index of herbivores did not differ between forest and open heathlands. Moreover, none of the plant species responded differently in the two habitats, when herbivores were removed. Our results suggest that intense and localised selective foraging by small mammals may have a more marked effect on vegetation than transient feeding by reindeer.\n
\n\n\n\n \n\n \n \n \n \n \n \n Summer warming and increased winter snow cover affect Sphagnum fuscum growth, structure and production in a sub-arctic bog.\n \n \n \n \n\n\n \n Dorrepaal, E.; Aerts, R.; Cornelissen, J. H. C.; Callaghan, T. V.; and Van Logtestijn, R. S. P.\n\n\n \n\n\n\n Global Change Biology, 10(1): 93–104. January 2004.\n \n\n\n\n
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\n\n\n@article{dorrepaal_summer_2004,\n\ttitle = {Summer warming and increased winter snow cover affect {Sphagnum} fuscum growth, structure and production in a sub-arctic bog},\n\tvolume = {10},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2003.00718.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2003.00718.x},\n\tabstract = {Sphagnum mosses form a major component of northern peatlands, which are expected to experience substantially higher increases in temperature and winter precipitation than the global average. Sphagnum may play an important role in the responses of the global carbon cycle to climate change. We investigated the responses of summer length growth, carpet structure and production in Sphagnum fuscum to experimentally induced changes in climate in a sub-arctic bog. Thereto, we used open-top chambers (OTCs) to create six climate scenarios including changes in summer temperatures, and changes in winter snow cover and spring temperatures. In winter, the OTCs doubled the snow thickness, resulting in 0.5–2.8°C higher average air temperatures. Spring air temperatures in OTCs increased by 1.0°C. Summer warming had a maximum effect of 0.9°C, while vapor pressure deficit was not affected. The climate manipulations had strong effects on S. fuscum. Summer warming enhanced the length increment by 42–62\\%, whereas bulk density decreased. This resulted in a trend (P{\\textless}0.10) of enhanced biomass production. Winter snow addition enhanced dry matter production by 33\\%, despite the fact that the length growth and bulk density did not change significantly. The addition of spring warming to snow addition alone did not significantly enhance this effect, but we may have missed part of the early spring growth. There were no interactions between the manipulations in summer and those in winter/spring, indicating that the effects were additive. Summer warming may in the long term negatively affect productivity through the adverse effects of changes in Sphagnum structure on moisture holding and transporting capacity. Moreover, the strong length growth enhancement may affect interactions with other mosses and vascular plants. Because winter snow addition enhanced the production of S. fuscum without affecting its structure, it may increase the carbon balance of northern peatlands.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Dorrepaal, Ellen and Aerts, Rien and Cornelissen, Johannes H. C. and Callaghan, Terry V. and Van Logtestijn, Richard S. P.},\n\tmonth = jan,\n\tyear = {2004},\n\tkeywords = {\\#nosource, Production, Sphagnum, climate change, global warming, peatlands, snow cover},\n\tpages = {93--104},\n}\n\n\n\n\n\n Sphagnum mosses form a major component of northern peatlands, which are expected to experience substantially higher increases in temperature and winter precipitation than the global average. Sphagnum may play an important role in the responses of the global carbon cycle to climate change. We investigated the responses of summer length growth, carpet structure and production in Sphagnum fuscum to experimentally induced changes in climate in a sub-arctic bog. Thereto, we used open-top chambers (OTCs) to create six climate scenarios including changes in summer temperatures, and changes in winter snow cover and spring temperatures. In winter, the OTCs doubled the snow thickness, resulting in 0.5–2.8°C higher average air temperatures. Spring air temperatures in OTCs increased by 1.0°C. Summer warming had a maximum effect of 0.9°C, while vapor pressure deficit was not affected. The climate manipulations had strong effects on S. fuscum. Summer warming enhanced the length increment by 42–62%, whereas bulk density decreased. This resulted in a trend (P\\textless0.10) of enhanced biomass production. Winter snow addition enhanced dry matter production by 33%, despite the fact that the length growth and bulk density did not change significantly. The addition of spring warming to snow addition alone did not significantly enhance this effect, but we may have missed part of the early spring growth. There were no interactions between the manipulations in summer and those in winter/spring, indicating that the effects were additive. Summer warming may in the long term negatively affect productivity through the adverse effects of changes in Sphagnum structure on moisture holding and transporting capacity. Moreover, the strong length growth enhancement may affect interactions with other mosses and vascular plants. Because winter snow addition enhanced the production of S. fuscum without affecting its structure, it may increase the carbon balance of northern peatlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of experimentally imposed climate scenarios on flowering phenology and flower production of subarctic bog species.\n \n \n \n \n\n\n \n Aerts, R.; Cornelissen, J. H. C.; Dorrepaal, E.; Van Logtestijn, R. S. P.; and Callaghan, T. V.\n\n\n \n\n\n\n Global Change Biology, 10(9): 1599–1609. September 2004.\n \n\n\n\n
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\n\n\n@article{aerts_effects_2004,\n\ttitle = {Effects of experimentally imposed climate scenarios on flowering phenology and flower production of subarctic bog species},\n\tvolume = {10},\n\tissn = {1365-2486},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2004.00815.x/abstract},\n\tdoi = {10.1111/j.1365-2486.2004.00815.x},\n\tabstract = {Climate scenarios for high-latitude areas predict not only increased summer temperatures, but also larger variation in snowfall and winter temperatures. By using open-top chambers, we experimentally manipulated both summer temperatures and winter and spring snow accumulations and temperatures independently in a blanket bog in subarctic Sweden, yielding six climate scenarios. We studied the effects of these scenarios on flowering phenology and flower production of Andromeda polifolia (woody evergreen) and Rubus chamaemorus (perennial herb) during 2 years. The second year of our study (2002) was characterized by unusually high spring and early summer temperatures. Our winter manipulations led to consistent increases in winter snow cover. As a result, average and minimum air and soil temperatures in the high snow cover treatments were higher than in the winter ambient treatments, whereas temperature fluctuations were smaller. Spring warming resulted in higher average, minimum, and maximum soil temperatures. Summer warming led to higher air and soil temperatures in mid-summer (June–July), but not in late summer (August–September). The unusually high temperatures in 2002 advanced the median flowering date by 2 weeks for both species in all treatments. Superimposed on this effect, we found that for both Andromeda and Rubus, all our climate treatments (except summer warming for Rubus) advanced flowering by 1–4 days. The total flower production of both species showed a more or less similar response: flower production in the warm year 2002 exceeded that in 2001 by far. However, in both species flower production was only stimulated by the spring-warming treatments. Our results show that the reproductive ecology of both species is very responsive to climate change but this response is very dependent on specific climate events, especially those that occur in winter and spring. This suggests that high-latitude climate change experiments should focus more on winter and spring events than has been the case so far.},\n\tlanguage = {en},\n\tnumber = {9},\n\turldate = {2017-02-08},\n\tjournal = {Global Change Biology},\n\tauthor = {Aerts, R. and Cornelissen, J. H. C. and Dorrepaal, E. and Van Logtestijn, R. S. P. and Callaghan, T. V.},\n\tmonth = sep,\n\tyear = {2004},\n\tkeywords = {\\#nosource, Andromeda polifolia, Rubus chamaemorus, global warming, phenology, sexual reproduction, winter temperature},\n\tpages = {1599--1609},\n}\n\n\n\n\n\n Climate scenarios for high-latitude areas predict not only increased summer temperatures, but also larger variation in snowfall and winter temperatures. By using open-top chambers, we experimentally manipulated both summer temperatures and winter and spring snow accumulations and temperatures independently in a blanket bog in subarctic Sweden, yielding six climate scenarios. We studied the effects of these scenarios on flowering phenology and flower production of Andromeda polifolia (woody evergreen) and Rubus chamaemorus (perennial herb) during 2 years. The second year of our study (2002) was characterized by unusually high spring and early summer temperatures. Our winter manipulations led to consistent increases in winter snow cover. As a result, average and minimum air and soil temperatures in the high snow cover treatments were higher than in the winter ambient treatments, whereas temperature fluctuations were smaller. Spring warming resulted in higher average, minimum, and maximum soil temperatures. Summer warming led to higher air and soil temperatures in mid-summer (June–July), but not in late summer (August–September). The unusually high temperatures in 2002 advanced the median flowering date by 2 weeks for both species in all treatments. Superimposed on this effect, we found that for both Andromeda and Rubus, all our climate treatments (except summer warming for Rubus) advanced flowering by 1–4 days. The total flower production of both species showed a more or less similar response: flower production in the warm year 2002 exceeded that in 2001 by far. However, in both species flower production was only stimulated by the spring-warming treatments. Our results show that the reproductive ecology of both species is very responsive to climate change but this response is very dependent on specific climate events, especially those that occur in winter and spring. This suggests that high-latitude climate change experiments should focus more on winter and spring events than has been the case so far.\n
\n\n\n\n \n\n \n \n \n \n \n \n Feeding physiology of the carnivorous gastropod Thais clavigera (Kuster): do they eat “soup”?.\n \n \n \n \n\n\n \n Lau, D. C. P.; and Leung, K. M. Y.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology, 312(1): 43–66. November 2004.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{lau_feeding_2004,\n\ttitle = {Feeding physiology of the carnivorous gastropod {Thais} clavigera ({Kuster}): do they eat “soup”?},\n\tvolume = {312},\n\tissn = {0022-0981},\n\tshorttitle = {Feeding physiology of the carnivorous gastropod {Thais} clavigera ({Kuster})},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0022098104003582},\n\tdoi = {10.1016/j.jembe.2004.06.002},\n\tabstract = {The ability to feed on suspended and dissolved organic nutrients may have been retained in predatory gastropods during evolution. The carnivorous muricid neogastropod Thais clavigera feeds on prey by boring through their shells, followed by extracellular digestion and suction of the nutrient-rich fluid of the prey's body tissues. This study reports on the effect of feeding on suspended and soluble organic nutrients (SSONs) on the survival, growth, and various physiological activities including scope for growth and glycogen stores of T. clavigera. Juvenile T. clavigera of similar shell length (23.8±1.7 mm) were either starved, fed with mussel Septifer virgatus, fed with SSONs from homogenized mussel flesh (S. virgatus), or fed with both mussels and SSONs, and kept in artificial seawater (salinity: 30‰) for 50 days. Ingestion of SSONs by the animals was significant. Feeding with the “soup” (i.e., SSONs) reduced tissue wastage and improved condition index of the snails. T. clavigera fed in this manner were intermediates between the starved and the mussel-fed groups in terms of mortality, growth, food consumption, respiration, scope for growth, and glycogen content measurements. Furthermore, T. clavigera fed with both mussels and SSONs exhibited an identical energy requirement and similar values of various physiological measurements as that of those fed solely on mussel flesh. Feeding of SSONs contributed \\>10\\% of the overall energy requirement when both SSONs and mussel prey were available. The results indicate that energy from suspended and dissolved organic nutrients can contribute to the maximization of energy input in T. clavigera, which may favor better survivorship and thus lifetime fitness.},\n\tnumber = {1},\n\turldate = {2017-05-27},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Lau, Danny C. P. and Leung, Kenneth M. Y.},\n\tmonth = nov,\n\tyear = {2004},\n\tkeywords = {\\#nosource, Dissolved organic matters, Nucella lapillus, Particulate organic matters, Seston, Whelk, eutrophication},\n\tpages = {43--66},\n}\n\n\n\n\n\n The ability to feed on suspended and dissolved organic nutrients may have been retained in predatory gastropods during evolution. The carnivorous muricid neogastropod Thais clavigera feeds on prey by boring through their shells, followed by extracellular digestion and suction of the nutrient-rich fluid of the prey's body tissues. This study reports on the effect of feeding on suspended and soluble organic nutrients (SSONs) on the survival, growth, and various physiological activities including scope for growth and glycogen stores of T. clavigera. Juvenile T. clavigera of similar shell length (23.8±1.7 mm) were either starved, fed with mussel Septifer virgatus, fed with SSONs from homogenized mussel flesh (S. virgatus), or fed with both mussels and SSONs, and kept in artificial seawater (salinity: 30‰) for 50 days. Ingestion of SSONs by the animals was significant. Feeding with the “soup” (i.e., SSONs) reduced tissue wastage and improved condition index of the snails. T. clavigera fed in this manner were intermediates between the starved and the mussel-fed groups in terms of mortality, growth, food consumption, respiration, scope for growth, and glycogen content measurements. Furthermore, T. clavigera fed with both mussels and SSONs exhibited an identical energy requirement and similar values of various physiological measurements as that of those fed solely on mussel flesh. Feeding of SSONs contributed >10% of the overall energy requirement when both SSONs and mussel prey were available. The results indicate that energy from suspended and dissolved organic nutrients can contribute to the maximization of energy input in T. clavigera, which may favor better survivorship and thus lifetime fitness.\n
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\n \n \n\n \n \n \n \n \n \n Availability and quality of herbivore winter browse in relation to tree height and snow depth.\n \n \n \n \n\n\n \n Nordengren, C.; Hofgaard, A.; and Ball, J. P.\n\n\n \n\n\n\n Annales Zoologici Fennici, 40(3): 305–314. 2003.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{nordengren_availability_2003,\n\ttitle = {Availability and quality of herbivore winter browse in relation to tree height and snow depth},\n\tvolume = {40},\n\tissn = {0003-455X},\n\turl = {http://www.jstor.org/stable/23736811},\n\tabstract = {The vertical distribution of biomass, nutrients, and concentrations of secondary defence compounds in the current annual growth of the main winter forage trees (birch and willows) of herbivores was studied in the mountain range of northern Scandinavia. In addition, forage availability in relation to snow accumulation was studied throughout winter. The quantity and quality of forage improved with the height of the trees, i.e. biomass and nitrogen concentrations increased, and fibre decreased. The concentration of defensive compounds increased with height for willow, but decreased for birch. Shoots of willow were of better quality than of birch. The negative effect of the higher levels of total defensive compounds in birch may to some extent be balanced by their higher nutrient content and total forage biomass as compared with that of willow, however willow had more available biomass within the heights browsed by herbivores. Although snow accumulation had significant effects on forage availability, the effects within the entire height range browsed by herbivores were small.},\n\tnumber = {3},\n\turldate = {2016-03-02},\n\tjournal = {Annales Zoologici Fennici},\n\tauthor = {Nordengren, Caroline and Hofgaard, Annika and Ball, John P.},\n\tyear = {2003},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {305--314},\n}\n\n\n\n\n\n The vertical distribution of biomass, nutrients, and concentrations of secondary defence compounds in the current annual growth of the main winter forage trees (birch and willows) of herbivores was studied in the mountain range of northern Scandinavia. In addition, forage availability in relation to snow accumulation was studied throughout winter. The quantity and quality of forage improved with the height of the trees, i.e. biomass and nitrogen concentrations increased, and fibre decreased. The concentration of defensive compounds increased with height for willow, but decreased for birch. Shoots of willow were of better quality than of birch. The negative effect of the higher levels of total defensive compounds in birch may to some extent be balanced by their higher nutrient content and total forage biomass as compared with that of willow, however willow had more available biomass within the heights browsed by herbivores. Although snow accumulation had significant effects on forage availability, the effects within the entire height range browsed by herbivores were small.\n
\n\n\n\n \n\n \n \n \n \n \n \n Holocene environmental change at Lake Njulla (999 m a.s.l.), northern Sweden: a comparison with four small nearby lakes alongan altitudinal gradient.\n \n \n \n \n\n\n \n Bigler, C.; Grahn, E.; Larocque, I.; Jeziorski, A.; and Hall, R.\n\n\n \n\n\n\n Journal of Paleolimnology, 29(1): 13–29. January 2003.\n 00089\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{bigler_holocene_2003,\n\ttitle = {Holocene environmental change at {Lake} {Njulla} (999 m a.s.l.), northern {Sweden}: a comparison with four small nearby lakes alongan altitudinal gradient},\n\tvolume = {29},\n\tissn = {0921-2728, 1573-0417},\n\tshorttitle = {Holocene environmental change at {Lake} {Njulla} (999 m a.s.l.), northern {Sweden}},\n\turl = {http://link.springer.com/article/10.1023/A:1022850925937},\n\tdoi = {10.1023/A:1022850925937},\n\tabstract = {We assess Holocene environmental change at alpine Lake Njulla(68°22′N, 18°42′E, 999 m a.s.l.) innorthernmost Sweden using sedimentary remains of chironomid head capsules anddiatoms. We apply regional calibration sets to quantitatively reconstruct meanJuly air temperature (using chironomids and diatoms) and lake-water pH(using diatoms). Both chironomids and diatoms infer highest temperatures(1.7–2.3°C above present-day estimates, includinga correction for glacio-isostatic land up-lift by0.6°C) during the early Holocene (c.9,500–8,500 cal. yrs BP). Diatoms suggest a decreasing lake-waterpH trend (c. 0.6 pH units) since the early Holocene. Usingdetrended canonical correspondence analysis (DCCA), we compare the Holocenedevelopment of diatom communities in Lake Njulla with four other nearby lakes(Lake 850, Lake Tibetanus, Vuoskkujávri, Vuolep Njakajaure) locatedalong an altitudinal gradient. All five lakes show similar initial DCCA scoresafter deglaciation, suggesting that similar environmental processes such ashigh erosion rates and low light availability associated with high summertemperature appear to have regulated the diatom community, favouring highabundances of Fragilaria species. Subsequently, the diatomassemblages develop in a directional manner, but timing and scale ofdevelopment differ substantially between lakes. This is attributed primarily todifferences in the local geology, which is controlling the lake-waterpH. Imposed on the basic geological setting, site-specific processessuch as vegetation development, climate, hydrological setting andin-lake processes appear to control lake development in northernSweden.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Bigler, Christian and Grahn, Evastina and Larocque, Isabelle and Jeziorski, Adam and Hall, Roland},\n\tmonth = jan,\n\tyear = {2003},\n\tnote = {00089},\n\tkeywords = {\\#nosource, Abisko, Mean July air temperature, Plant macrofossils, chironomids, diatoms, lake development, lake-water pH, quantitative reconstruction},\n\tpages = {13--29},\n}\n\n\n\n\n\n We assess Holocene environmental change at alpine Lake Njulla(68°22′N, 18°42′E, 999 m a.s.l.) innorthernmost Sweden using sedimentary remains of chironomid head capsules anddiatoms. We apply regional calibration sets to quantitatively reconstruct meanJuly air temperature (using chironomids and diatoms) and lake-water pH(using diatoms). Both chironomids and diatoms infer highest temperatures(1.7–2.3°C above present-day estimates, includinga correction for glacio-isostatic land up-lift by0.6°C) during the early Holocene (c.9,500–8,500 cal. yrs BP). Diatoms suggest a decreasing lake-waterpH trend (c. 0.6 pH units) since the early Holocene. Usingdetrended canonical correspondence analysis (DCCA), we compare the Holocenedevelopment of diatom communities in Lake Njulla with four other nearby lakes(Lake 850, Lake Tibetanus, Vuoskkujávri, Vuolep Njakajaure) locatedalong an altitudinal gradient. All five lakes show similar initial DCCA scoresafter deglaciation, suggesting that similar environmental processes such ashigh erosion rates and low light availability associated with high summertemperature appear to have regulated the diatom community, favouring highabundances of Fragilaria species. Subsequently, the diatomassemblages develop in a directional manner, but timing and scale ofdevelopment differ substantially between lakes. This is attributed primarily todifferences in the local geology, which is controlling the lake-waterpH. Imposed on the basic geological setting, site-specific processessuch as vegetation development, climate, hydrological setting andin-lake processes appear to control lake development in northernSweden.\n
\n\n\n\n \n\n \n \n \n \n \n \n Chironomids as quantitative indicators of mean July air temperature: validation by comparison with century-long meteorological records from northern Sweden.\n \n \n \n \n\n\n \n Larocque, I.; and Hall, R. I.\n\n\n \n\n\n\n Journal of Paleolimnology, 29(4): 475–493. May 2003.\n 00093\n\n\n\n
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\n\n\n@article{larocque_chironomids_2003,\n\ttitle = {Chironomids as quantitative indicators of mean {July} air temperature: validation by comparison with century-long meteorological records from northern {Sweden}},\n\tvolume = {29},\n\tissn = {0921-2728, 1573-0417},\n\tshorttitle = {Chironomids as quantitative indicators of mean {July} air temperature},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1023/A%3A1024423813384},\n\tdoi = {10.1023/A:1024423813384},\n\tabstract = {00080},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2015-10-04},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Larocque, Isabelle and Hall, Roland I.},\n\tmonth = may,\n\tyear = {2003},\n\tnote = {00093},\n\tkeywords = {\\#nosource, Geochemistry, Hydrobiology, Hydrogeology, Meteorology/Climatology, Sedimentology, Temperature estimates, Validation, chironomids, climatic change, northern sweden, transfer function},\n\tpages = {475--493},\n}\n\n\n\n\n\n 00080\n
\n\n\n\n \n\n \n \n \n \n \n \n Do Diatom, Chironomid, and Pollen Records Consistently Infer Holocene July Air Temperature? A Comparison Using Sediment Cores from Four Alpine Lakes in Northern Sweden.\n \n \n \n \n\n\n \n Rosén, P.; Segerström, U.; Eriksson, L.; and Renberg, I.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 35(3): 279–290. August 2003.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{rosen_diatom_2003,\n\ttitle = {Do {Diatom}, {Chironomid}, and {Pollen} {Records} {Consistently} {Infer} {Holocene} {July} {Air} {Temperature}? {A} {Comparison} {Using} {Sediment} {Cores} from {Four} {Alpine} {Lakes} in {Northern} {Sweden}},\n\tvolume = {35},\n\tissn = {1523-0430},\n\tshorttitle = {Do {Diatom}, {Chironomid}, and {Pollen} {Records} {Consistently} {Infer} {Holocene} {July} {Air} {Temperature}?},\n\turl = {http://aaarjournal.org.proxy.ub.umu.se/doi/abs/10.1657/1523-0430(2003)035%5B0279:DDCAPR%5D2.0.CO;2},\n\tdoi = {10.1657/1523-0430(2003)035[0279:DDCAPR]2.0.CO;2},\n\tabstract = {The aim of this study is to assess the performance of diatom, chironomid, and pollen transfer functions for inferences of July air temperature during the Holocene using sediments from four alpine lakes in an area with low human impact in northern Sweden. The study demonstrates that diatom, chironomid, and pollen assemblages in the sediment cores contain climate information so that present-day temperature at each lake can be inferred with reasonable confidence for most proxies. Most proxy records from the sites consistently infer a long-term decreasing trend in July air temperature from ca. 6000 cal yr BP until the present. However, there are also large variations in the temporal patterns of the inferred temperatures during some periods, especially before 7000 cal yr BP, when there are also nonsynchronous changes in loss-on-ignition in the four lakes. This variability indicates that local conditions in the catchments (influence of snowfields, soil-forming processes) had a large impact on the organism assemblages in the early Holocene. Long-distance transport of pollen into high alpine lakes makes temperature inferences from pollen transfer functions unreliable. Due to the uncertainties of the methods, predictive errors of the transfer functions, and variability caused by local catchment/lake characteristics, only long-term trends in climate can be inferred. High-resolution studies using diatoms, chironomids, and pollen for climate reconstruction are probably not meaningful during periods with small changes in climate ({\\textless}1°C). Future research should concentrate on low-resolution, multiproxy, and multilake studies to further understand the relationship between the proxies and climate.},\n\tnumber = {3},\n\turldate = {2015-10-04},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Rosén, Peter and Segerström, Ulf and Eriksson, Lars and Renberg, Ingemar},\n\tmonth = aug,\n\tyear = {2003},\n\tkeywords = {\\#nosource},\n\tpages = {279--290},\n}\n\n\n\n\n\n The aim of this study is to assess the performance of diatom, chironomid, and pollen transfer functions for inferences of July air temperature during the Holocene using sediments from four alpine lakes in an area with low human impact in northern Sweden. The study demonstrates that diatom, chironomid, and pollen assemblages in the sediment cores contain climate information so that present-day temperature at each lake can be inferred with reasonable confidence for most proxies. Most proxy records from the sites consistently infer a long-term decreasing trend in July air temperature from ca. 6000 cal yr BP until the present. However, there are also large variations in the temporal patterns of the inferred temperatures during some periods, especially before 7000 cal yr BP, when there are also nonsynchronous changes in loss-on-ignition in the four lakes. This variability indicates that local conditions in the catchments (influence of snowfields, soil-forming processes) had a large impact on the organism assemblages in the early Holocene. Long-distance transport of pollen into high alpine lakes makes temperature inferences from pollen transfer functions unreliable. Due to the uncertainties of the methods, predictive errors of the transfer functions, and variability caused by local catchment/lake characteristics, only long-term trends in climate can be inferred. High-resolution studies using diatoms, chironomids, and pollen for climate reconstruction are probably not meaningful during periods with small changes in climate (\\textless1°C). Future research should concentrate on low-resolution, multiproxy, and multilake studies to further understand the relationship between the proxies and climate.\n
\n\n\n\n \n\n \n \n \n \n \n \n Diatoms as quantitative indicators of July temperature: a validation attempt at century-scale with meteorological data from northern Sweden.\n \n \n \n \n\n\n \n Bigler, C.; and Hall, R. I.\n\n\n \n\n\n\n Palaeogeography, Palaeoclimatology, Palaeoecology, 189(3–4): 147–160. January 2003.\n \n\n\n\n
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\n\n\n@article{bigler_diatoms_2003,\n\ttitle = {Diatoms as quantitative indicators of {July} temperature: a validation attempt at century-scale with meteorological data from northern {Sweden}},\n\tvolume = {189},\n\tissn = {0031-0182},\n\tshorttitle = {Diatoms as quantitative indicators of {July} temperature},\n\turl = {https://www.sciencedirect.com/science/article/pii/S0031018202006387},\n\tdoi = {10.1016/S0031-0182(02)00638-7},\n\tabstract = {This study evaluates the ability of diatoms to estimate past changes in temperature by directly comparing diatom-based inferences of mean July air temperature (July T) with measured values of century-long meteorological records. The comparison includes sediment cores from three lakes in northern Sweden (Alanen Laanijärvi, 365 m above sea level (a.s.l.), Lake 850, 850 m a.s.l. and Lake Njulla, 999 m a.s.l.) dated by radioisotopic methods (210Pb, 137Cs) and records from meteorological stations in Kiruna and Abisko. In the sediment cores of all three study lakes, benthic species dominate the diatom assemblages with percent abundance ranging from 60 to 80\\%. Over the past century, the diatom-based quantitative July T inferences (weighted averaging partial least squares regression and calibration) based on a regional calibration set correspond in general closely with the meteorological records. In addition, the proportion of planktonic diatoms in the stratigraphy reflects the meteorological record as well. For example, in Alanen Laanijärvi, the proportion of planktonic diatoms (e.g. Cyclotella comensis) has increased markedly since 1985, coincident with a marked increase of measured July T (\\>1°C) at the meteorological station in nearby Kiruna. In contrast, July T in Abisko has remained relatively constant since 1985 and relatively little changes are observed in diatom assemblages in the two nearby lakes, Lake 850 and Lake Njulla. Interestingly, periods of relatively weak correspondence between measured and inferred July T (at Lake 850 from 1910 to 1940, at Lake Njulla from 1955 to 1990) correspond with periods when diatom-inferred lake-water pH shows distinct trends of lake-water pH change. Because lake-water pH is a stronger factor influencing diatom community composition than July T, the accuracy of diatom-inferred July T appears to be reduced during periods when lake-water pH fluctuates. Overall, we conclude that diatoms can provide reliable estimates of July T over the past century from sediment samples in northern Sweden and the reliability of the inferences further increases when lake-water pH remains constant. One palaeoecological implication based on these findings is that the early Holocene is likely a problematic period for estimating July T from diatoms, because natural processes such as soil development, catchment stabilisation and weathering of bedrock resulted in a marked natural decline of lake-water pH. Similarly, short-term stochastic events, such as sediment in-wash due to erosional events, forest clearance and forest fires, also may lead to inaccurate diatom–temperature inferences through changes in lake-water pH. In order to identify periods that may affect the accuracy of diatom-based July T inferences, we suggest that diatom analyses should be combined with other palaeoecological proxy indicators (e.g. pollen, chironomids).},\n\tnumber = {3–4},\n\turldate = {2017-02-07},\n\tjournal = {Palaeogeography, Palaeoclimatology, Palaeoecology},\n\tauthor = {Bigler, Christian and Hall, Roland I.},\n\tmonth = jan,\n\tyear = {2003},\n\tkeywords = {\\#nosource, WA–PLS model validation, abisko, climatic change, diatom algae, palaeolimnology, radioisotopic dating, transfer functions},\n\tpages = {147--160},\n}\n\n\n\n\n\n This study evaluates the ability of diatoms to estimate past changes in temperature by directly comparing diatom-based inferences of mean July air temperature (July T) with measured values of century-long meteorological records. The comparison includes sediment cores from three lakes in northern Sweden (Alanen Laanijärvi, 365 m above sea level (a.s.l.), Lake 850, 850 m a.s.l. and Lake Njulla, 999 m a.s.l.) dated by radioisotopic methods (210Pb, 137Cs) and records from meteorological stations in Kiruna and Abisko. In the sediment cores of all three study lakes, benthic species dominate the diatom assemblages with percent abundance ranging from 60 to 80%. Over the past century, the diatom-based quantitative July T inferences (weighted averaging partial least squares regression and calibration) based on a regional calibration set correspond in general closely with the meteorological records. In addition, the proportion of planktonic diatoms in the stratigraphy reflects the meteorological record as well. For example, in Alanen Laanijärvi, the proportion of planktonic diatoms (e.g. Cyclotella comensis) has increased markedly since 1985, coincident with a marked increase of measured July T (>1°C) at the meteorological station in nearby Kiruna. In contrast, July T in Abisko has remained relatively constant since 1985 and relatively little changes are observed in diatom assemblages in the two nearby lakes, Lake 850 and Lake Njulla. Interestingly, periods of relatively weak correspondence between measured and inferred July T (at Lake 850 from 1910 to 1940, at Lake Njulla from 1955 to 1990) correspond with periods when diatom-inferred lake-water pH shows distinct trends of lake-water pH change. Because lake-water pH is a stronger factor influencing diatom community composition than July T, the accuracy of diatom-inferred July T appears to be reduced during periods when lake-water pH fluctuates. Overall, we conclude that diatoms can provide reliable estimates of July T over the past century from sediment samples in northern Sweden and the reliability of the inferences further increases when lake-water pH remains constant. One palaeoecological implication based on these findings is that the early Holocene is likely a problematic period for estimating July T from diatoms, because natural processes such as soil development, catchment stabilisation and weathering of bedrock resulted in a marked natural decline of lake-water pH. Similarly, short-term stochastic events, such as sediment in-wash due to erosional events, forest clearance and forest fires, also may lead to inaccurate diatom–temperature inferences through changes in lake-water pH. In order to identify periods that may affect the accuracy of diatom-based July T inferences, we suggest that diatom analyses should be combined with other palaeoecological proxy indicators (e.g. pollen, chironomids).\n
\n\n\n\n \n\n \n \n \n \n \n Allochthonous organic carbon decreases pelagic energy mobilization in lakes.\n \n \n \n\n\n \n Jansson, M.; Karlsson, J.; and Blomqvist, P.\n\n\n \n\n\n\n Limnology and Oceanography, 48(4): 1711–1716. July 2003.\n 00038\n\n\n\n
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\n\n\n@article{jansson_allochthonous_2003,\n\ttitle = {Allochthonous organic carbon decreases pelagic energy mobilization in lakes},\n\tvolume = {48},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2003.48.4.1711},\n\tabstract = {Over the past decade, it has been Shown that unproductive lakes worldwide are net heterotrophic because bacterial respiration of allochthonous. organic carbon (AOC) makes community respiration exceed primary production. Net heterotrophy means that aquatic systems are net sources of CO2 to the atmosphere but also that bacterial utilization of AOC increases bacterioplankton production (BP) and bacterial uptake of limiting inorganic nutrients at the expense of phytoplankton production (PP). We studied 15 unproductive lakes in northern Sweden with dissolved organic carbon concentrations between 3 and 22 mg L-1. We found a highly significant negative relationship between the degree of heterotrophy and total pelagic energy mobilization (PP + BP based on AOC) per unit of limiting nutrient. We suggest that this is because the high cell phosphorous (P) requirement of bacteria makes energy mobilization per P unit considerably lower in bacterioplankton than in phytoplankton. We also suggest that the productivity of the entire pelagic ecosystem is determined by the availability of inorganic nutrients and AOC and by whether nutrients are allocated to BP or PP.},\n\tlanguage = {English},\n\tnumber = {4},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Jansson, M. and Karlsson, J. and Blomqvist, P.},\n\tmonth = jul,\n\tyear = {2003},\n\tnote = {00038},\n\tkeywords = {\\#nosource, bacteria, bacterioplankton production, efficiency, humic lakes, nutrient limitation, ortrasket, phosphorus, phytoplankton, plankton, systems},\n\tpages = {1711--1716},\n}\n\n\n\n\n\n Over the past decade, it has been Shown that unproductive lakes worldwide are net heterotrophic because bacterial respiration of allochthonous. organic carbon (AOC) makes community respiration exceed primary production. Net heterotrophy means that aquatic systems are net sources of CO2 to the atmosphere but also that bacterial utilization of AOC increases bacterioplankton production (BP) and bacterial uptake of limiting inorganic nutrients at the expense of phytoplankton production (PP). We studied 15 unproductive lakes in northern Sweden with dissolved organic carbon concentrations between 3 and 22 mg L-1. We found a highly significant negative relationship between the degree of heterotrophy and total pelagic energy mobilization (PP + BP based on AOC) per unit of limiting nutrient. We suggest that this is because the high cell phosphorous (P) requirement of bacteria makes energy mobilization per P unit considerably lower in bacterioplankton than in phytoplankton. We also suggest that the productivity of the entire pelagic ecosystem is determined by the availability of inorganic nutrients and AOC and by whether nutrients are allocated to BP or PP.\n
\n\n\n\n \n\n \n \n \n \n \n Control of zooplankton dependence on allochthonous organic carbon in humic and clear-water lakes in northern Sweden.\n \n \n \n\n\n \n Karlsson, J.; Jonsson, A.; Meili, M.; and Jansson, M.\n\n\n \n\n\n\n Limnology and Oceanography, 48(1): 269–276. January 2003.\n \n\n\n\n
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\n\n\n@article{karlsson_control_2003,\n\ttitle = {Control of zooplankton dependence on allochthonous organic carbon in humic and clear-water lakes in northern {Sweden}},\n\tvolume = {48},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2003.48.1.0269},\n\tabstract = {We compared the stable carbon isotopic composition (delta(13)C) of crustacean zooplankton with that of potential carbon sources in 15 lakes in northern Sweden with different dissolved organic carbon (DOC) concentrations (2-9 mg L-1) to test the hypothesis that zooplankton depended more on allochthonous carbon in humic lakes than in clear-water lakes. Based on delta(13)C signature, we found that the pool of organic matter in the lakes was dominated by carbon of allochthonous origin over the whole DOC gradient. Zooplankton were generally depleted in C-13 compared to organic matter in the catchment, particulate organic matter in the lake water, and shallow surface sediment. However, the isotopic composition of zooplankton could not be explained without a significant contribution from both allochthonous and autochthonous carbon sources in all lakes. The relative importance of these two carbon sources did not relate to the concentration of, or proportion between, allochthonous and autochthonous organic carbon in the water. Instead, the proportion between allochthonous and autochthonous carbon in the crustacean zooplankton was consistent with a rather conservative use of the energy mobilized by bacterioplankton and phytoplankton in the lakes.},\n\tlanguage = {English},\n\tnumber = {1},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Karlsson, J. and Jonsson, A. and Meili, M. and Jansson, M.},\n\tmonth = jan,\n\tyear = {2003},\n\tkeywords = {\\#nosource, availability, discrimination, food webs, fractionation, growth-rate, marine, matter, phytoplankton, stable-isotope analysis, tjeukemeer netherlands},\n\tpages = {269--276},\n}\n\n\n\n\n\n We compared the stable carbon isotopic composition (delta(13)C) of crustacean zooplankton with that of potential carbon sources in 15 lakes in northern Sweden with different dissolved organic carbon (DOC) concentrations (2-9 mg L-1) to test the hypothesis that zooplankton depended more on allochthonous carbon in humic lakes than in clear-water lakes. Based on delta(13)C signature, we found that the pool of organic matter in the lakes was dominated by carbon of allochthonous origin over the whole DOC gradient. Zooplankton were generally depleted in C-13 compared to organic matter in the catchment, particulate organic matter in the lake water, and shallow surface sediment. However, the isotopic composition of zooplankton could not be explained without a significant contribution from both allochthonous and autochthonous carbon sources in all lakes. The relative importance of these two carbon sources did not relate to the concentration of, or proportion between, allochthonous and autochthonous organic carbon in the water. Instead, the proportion between allochthonous and autochthonous carbon in the crustacean zooplankton was consistent with a rather conservative use of the energy mobilized by bacterioplankton and phytoplankton in the lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Decomposition of sub-arctic plants with differing nitrogen economies: a functional role for hemiparasites.\n \n \n \n \n\n\n \n Quested, H. M.; Cornelissen, J. H. C.; Press, M. C.; Callaghan, T. V.; Aerts, R.; Trosien, F.; Riemann, P.; Gwynn-Jones, D.; Kondratchuk, A.; and Jonasson, S. E.\n\n\n \n\n\n\n Ecology, 84(12): 3209–3221. December 2003.\n \n\n\n\n
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\n\n\n@article{quested_decomposition_2003,\n\ttitle = {Decomposition of sub-arctic plants with differing nitrogen economies: a functional role for hemiparasites},\n\tvolume = {84},\n\tissn = {0012-9658},\n\tshorttitle = {Decomposition of sub-arctic plants with differing nitrogen economies},\n\turl = {http://www.esajournals.org.proxy.ub.umu.se/doi/abs/10.1890/02-0426},\n\tdoi = {10.1890/02-0426},\n\tabstract = {Although hemiparasitic plants have a number of roles in shaping the structure and composition of plant communities, the impact of this group on ecosystem processes, such as decomposition and nutrient cycling, has been poorly studied. In order to better understand the potential role of hemiparasites in these processes, a comparison of leaf and litter tissue quality, nitrogen (N) resorption, and decomposability with those of a wide range of other plant groups (involving a total of 72 species and including other groups with access to alternative nutrient sources, such as nitrogen fixers and carnivorous plants) was undertaken in several sub-arctic habitats. The foliar N concentration of hemiparasites generally exceeded that of co-occurring species. Further, hemiparasites (and N fixers) exhibited lower N resorption efficiencies than their counterparts with no major alternative N source. As a consequence, annual and perennial hemiparasite litter contained, on average, 3.1\\% and 1.9\\% N, respectively, compared with 0.77–1.1\\% for groups without a major alternative N source. Hemiparasite litter lost significantly more mass during decomposition than many, but not all, co-occurring species. These results were combined with those of a litter trapping experiment to assess the potential impact of hemiparasites on nutrient cycling. The common sub-arctic hemiparasite Bartsia alpina was estimated to increase the total annual N input from litter to the soil by ∼42\\% within 5 cm of its stems, and by ∼53\\% across a site with a Bartsia alpina stem density of 43 stems/m2. Our results therefore provide clear evidence in favor of a novel mechanism by which hemiparasites (in parallel with N-fixing species) may influence ecosystems in which they occur. Through the production of nutrient rich, rapidly decomposing litter, they have the potential to greatly enhance the availability of nutrients within patches where they are abundant, with possible consequent effects on small-scale biodiversity.},\n\tnumber = {12},\n\turldate = {2015-10-04},\n\tjournal = {Ecology},\n\tauthor = {Quested, Helen M. and Cornelissen, J. Hans C. and Press, Malcolm C. and Callaghan, Terry V. and Aerts, Rien and Trosien, Frank and Riemann, Petra and Gwynn-Jones, Dylan and Kondratchuk, Alexandra and Jonasson, Sven E.},\n\tmonth = dec,\n\tyear = {2003},\n\tkeywords = {\\#nosource, Bartsia alpina, Decomposition, Nitrogen, hemiparasite, leaf, life form, nitrogen-fixing plants, nutrient cycling, resorption, sub-arctic habitats},\n\tpages = {3209--3221},\n}\n\n\n\n\n\n Although hemiparasitic plants have a number of roles in shaping the structure and composition of plant communities, the impact of this group on ecosystem processes, such as decomposition and nutrient cycling, has been poorly studied. In order to better understand the potential role of hemiparasites in these processes, a comparison of leaf and litter tissue quality, nitrogen (N) resorption, and decomposability with those of a wide range of other plant groups (involving a total of 72 species and including other groups with access to alternative nutrient sources, such as nitrogen fixers and carnivorous plants) was undertaken in several sub-arctic habitats. The foliar N concentration of hemiparasites generally exceeded that of co-occurring species. Further, hemiparasites (and N fixers) exhibited lower N resorption efficiencies than their counterparts with no major alternative N source. As a consequence, annual and perennial hemiparasite litter contained, on average, 3.1% and 1.9% N, respectively, compared with 0.77–1.1% for groups without a major alternative N source. Hemiparasite litter lost significantly more mass during decomposition than many, but not all, co-occurring species. These results were combined with those of a litter trapping experiment to assess the potential impact of hemiparasites on nutrient cycling. The common sub-arctic hemiparasite Bartsia alpina was estimated to increase the total annual N input from litter to the soil by ∼42% within 5 cm of its stems, and by ∼53% across a site with a Bartsia alpina stem density of 43 stems/m2. Our results therefore provide clear evidence in favor of a novel mechanism by which hemiparasites (in parallel with N-fixing species) may influence ecosystems in which they occur. Through the production of nutrient rich, rapidly decomposing litter, they have the potential to greatly enhance the availability of nutrients within patches where they are abundant, with possible consequent effects on small-scale biodiversity.\n
\n\n\n\n \n\n \n \n \n \n \n Sources of carbon dioxide supersaturation in clearwater and humic lakes in northern Sweden.\n \n \n \n\n\n \n Jonsson, A.; Karlsson, J.; and Jansson, M.\n\n\n \n\n\n\n Ecosystems, 6(3): 224–235. April 2003.\n \n\n\n\n
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\n\n\n@article{jonsson_sources_2003,\n\ttitle = {Sources of carbon dioxide supersaturation in clearwater and humic lakes in northern {Sweden}},\n\tvolume = {6},\n\tissn = {1432-9840},\n\tdoi = {10.1007/s10021-002-0200-y},\n\tabstract = {Partial pressure (pCO(2)) and flux to the atmosphere of carbon dioxide (CO2) were studied in northern alpine and forest lakes along a gradient of dissolved organic carbon (DOC) content (0.4-9.9 mg L-1). Sixteen lakes were each sampled three times over the course of the ice-free season, and an additional 35 lakes were sampled once at midsummer. pCO(2) data were acquired in the field by a headspace equilibration technique. Most lakes were supersaturated with CO2 along the entire DOC gradient, with relatively small seasonal differences. pCO(2) was positively correlated to DOC content, reflecting a close dependence between allochthonous DOC in-put and heterotrophic respiration in the lakes. Fluxes of CO2 to the atmosphere were estimated from the pCO(2) measurements. Benthic respiration was indicated to be important for CO2 emission in lakes with high DOC concentrations. In lakes with low DOC concentrations, pelagic mineralization alone was sufficient to account for a large part of the estimated fluxes.},\n\tlanguage = {English},\n\tnumber = {3},\n\tjournal = {Ecosystems},\n\tauthor = {Jonsson, A. and Karlsson, J. and Jansson, M.},\n\tmonth = apr,\n\tyear = {2003},\n\tkeywords = {\\#nosource, Mineralization, alpine lakes, aquatic systems, benthic respiration, carbon dioxide, dissolved organic carbon, forest lakes, growth, organic-carbon, pelagic mineralization, phytoplankton production, respiration, surface waters, wisconsin},\n\tpages = {224--235},\n}\n\n\n\n\n\n Partial pressure (pCO(2)) and flux to the atmosphere of carbon dioxide (CO2) were studied in northern alpine and forest lakes along a gradient of dissolved organic carbon (DOC) content (0.4-9.9 mg L-1). Sixteen lakes were each sampled three times over the course of the ice-free season, and an additional 35 lakes were sampled once at midsummer. pCO(2) data were acquired in the field by a headspace equilibration technique. Most lakes were supersaturated with CO2 along the entire DOC gradient, with relatively small seasonal differences. pCO(2) was positively correlated to DOC content, reflecting a close dependence between allochthonous DOC in-put and heterotrophic respiration in the lakes. Fluxes of CO2 to the atmosphere were estimated from the pCO(2) measurements. Benthic respiration was indicated to be important for CO2 emission in lakes with high DOC concentrations. In lakes with low DOC concentrations, pelagic mineralization alone was sufficient to account for a large part of the estimated fluxes.\n
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\n \n \n\n \n \n \n \n \n \n Natural causes of the tundra-taiga boundary.\n \n \n \n \n\n\n \n Sveinbjörnsson, B.; Hofgaard, A.; and Lloyd, A.\n\n\n \n\n\n\n Ambio, 12: 23–29. 2002.\n 00077\n\n\n\n
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\n\n\n\n@article{sveinbjornsson_natural_2002,\n\ttitle = {Natural causes of the tundra-taiga boundary},\n\tvolume = {12},\n\turl = {http://www.jstor.org/stable/25094572},\n\tdoi = {https://www.jstor.org/stable/25094572},\n\turldate = {2017-01-13},\n\tjournal = {Ambio},\n\tauthor = {Sveinbjörnsson, Bjartmar and Hofgaard, Annika and Lloyd, Andrea},\n\tyear = {2002},\n\tnote = {00077},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {23--29},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n How Can the Dynamics of the Tundra-Taiga Boundary Be Remotely Monitored?.\n \n \n \n \n\n\n \n Rees, G.; Brown, I.; Mikkola, K.; Virtanen, T.; and Werkman, B.\n\n\n \n\n\n\n Ambio, 12: 56–62. 2002.\n \n\n\n\n
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\n\n\n@article{rees_how_2002,\n\ttitle = {How {Can} the {Dynamics} of the {Tundra}-{Taiga} {Boundary} {Be} {Remotely} {Monitored}?},\n\tvolume = {12},\n\tissn = {0044-7447},\n\turl = {http://www.jstor.org/stable/25094576},\n\tabstract = {This paper discusses some of the difficulties in establishing the location of the Arctic treeline and forest line on a circumpolar basis, and the contribution that remote sensing, particularly from spaceborne platforms, can make in resolving them. Spaceborne techniques can provide spatial resolutions as fine as a few meters, although the requirements for regional or global coverage are likely to limit the resolution to 30 to 100 m. Since this will preclude the identification of individual trees, the definition of the treeline will be based on statistical parameters estimated from satellite images. The optimum criteria for these parameters remain to be determined. Most remote-sensing observations that are suited to the measurement of the distribution of vegetation, and identification of its type, are based on the visible and near-infrared (VIR) parts of the electromagnetic spectrum, although there is increasing interest in the use of active microwave (radar) techniques. We discuss the basis of both types of approach and the techniques that follow from them, and present 3 case studies from the Russian Arctic.},\n\turldate = {2018-06-11},\n\tjournal = {Ambio},\n\tauthor = {Rees, Gareth and Brown, Ian and Mikkola, Kari and Virtanen, Tarmo and Werkman, Ben},\n\tyear = {2002},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {56--62},\n}\n\n\n\n\n\n This paper discusses some of the difficulties in establishing the location of the Arctic treeline and forest line on a circumpolar basis, and the contribution that remote sensing, particularly from spaceborne platforms, can make in resolving them. Spaceborne techniques can provide spatial resolutions as fine as a few meters, although the requirements for regional or global coverage are likely to limit the resolution to 30 to 100 m. Since this will preclude the identification of individual trees, the definition of the treeline will be based on statistical parameters estimated from satellite images. The optimum criteria for these parameters remain to be determined. Most remote-sensing observations that are suited to the measurement of the distribution of vegetation, and identification of its type, are based on the visible and near-infrared (VIR) parts of the electromagnetic spectrum, although there is increasing interest in the use of active microwave (radar) techniques. We discuss the basis of both types of approach and the techniques that follow from them, and present 3 case studies from the Russian Arctic.\n
\n\n\n\n \n\n \n \n \n \n \n \n The Tundra-Taiga Interface and Its Dynamics: Concepts and Applications.\n \n \n \n \n\n\n \n Callaghan, T. V.; Werkman, B. R.; and Crawford, R. M. M.\n\n\n \n\n\n\n Ambio, 12: 6–14. 2002.\n Publisher: [Springer, Royal Swedish Academy of Sciences]\n\n\n\n
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\n\n\n@article{callaghan_tundra-taiga_2002,\n\ttitle = {The {Tundra}-{Taiga} {Interface} and {Its} {Dynamics}: {Concepts} and {Applications}},\n\tvolume = {12},\n\tissn = {0044-7447},\n\tshorttitle = {The {Tundra}-{Taiga} {Interface} and {Its} {Dynamics}},\n\turl = {https://www.jstor.org/stable/25094570},\n\tabstract = {The tundra-taiga interface is a dominant vegetation boundary that is related to climate and has an importance at a global level for its contribution to land atmosphere interactions, biodiversity and land use. However, our understanding of the precise location, dynamics and characteristics of the boundary, and its environmental and biotic drivers at a circumpolar level is poor. Our understanding has been constrained for various reasons, perhaps including a quest by researchers to denote 2- or even 3-dimensional tree distribution limits to a single line on a map. Current rapid sociological and environmental changes in the north necessitate better definitions to be made of characteristics associated with the tundra-taiga interface so that changes can be monitored and identified, and implications of these changes can be assessed. This concept paper introduces some of the complexities of adequately defining the boundary and suggests characteristics and processes that could focus future research at a collaborative, circumpolar level to create baseline data and to monitor and predict changes in the boundary zone.},\n\turldate = {2024-03-27},\n\tjournal = {Ambio},\n\tauthor = {Callaghan, Terry V. and Werkman, Ben R. and Crawford, Robert. M. M.},\n\tyear = {2002},\n\tnote = {Publisher: [Springer, Royal Swedish Academy of Sciences]},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {6--14},\n}\n\n\n\n\n\n The tundra-taiga interface is a dominant vegetation boundary that is related to climate and has an importance at a global level for its contribution to land atmosphere interactions, biodiversity and land use. However, our understanding of the precise location, dynamics and characteristics of the boundary, and its environmental and biotic drivers at a circumpolar level is poor. Our understanding has been constrained for various reasons, perhaps including a quest by researchers to denote 2- or even 3-dimensional tree distribution limits to a single line on a map. Current rapid sociological and environmental changes in the north necessitate better definitions to be made of characteristics associated with the tundra-taiga interface so that changes can be monitored and identified, and implications of these changes can be assessed. This concept paper introduces some of the complexities of adequately defining the boundary and suggests characteristics and processes that could focus future research at a collaborative, circumpolar level to create baseline data and to monitor and predict changes in the boundary zone.\n
\n\n\n\n \n\n \n \n \n \n \n \n Swedish tree rings provide new evidence in support of a major, widespread environmental disruption in 1628 BC.\n \n \n \n \n\n\n \n Grudd, H.; Briffa, K. R.; Gunnarson, B. E.; and Linderholm, H. W.\n\n\n \n\n\n\n In Chambers, F.; and Olge, M., editor(s), Climate Change: Critical Concepts in the Environment, volume 2, pages 1616. Routledge, Taylor Francis Group, 2002.\n \n\n\n\n
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\n\n\n\n@incollection{grudd_swedish_2002,\n\ttitle = {Swedish tree rings provide new evidence in support of a major, widespread environmental disruption in 1628 {BC}},\n\tvolume = {2},\n\tisbn = {978-0-415-27656-6},\n\turl = {https://books.google.com/books?hl=en&lr=&id=EZXj87n_mJgC&oi=fnd&pg=PA296&dq=%22imprint+in+the+annual+width+of+tree+rings%22+%22in+1984,+LaMarche+and%22+%22for+measurement+error+and+averaged+to+produce%22+%22in+tree-ring+chronology+construction+to+highlight+a%22+&ots=WTt_QDA1Kw&sig=eneAY8W5GHTW0wYsfjlq6Vryclw},\n\turldate = {2017-01-13},\n\tbooktitle = {Climate {Change}: {Critical} {Concepts} in the {Environment}},\n\tpublisher = {Routledge, Taylor Francis Group},\n\tauthor = {Grudd, Håkan and Briffa, Keith R. and Gunnarson, Bjorn E. and Linderholm, Hans W.},\n\teditor = {Chambers, Frank and Olge, Michael},\n\tyear = {2002},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {1616},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Quantitative multiproxy assessment of long-term patterns of Holocene environmental change from a small lake near Abisko, northern Sweden.\n \n \n \n \n\n\n \n Bigler, C.; Larocque, I.; Peglar, S. M.; Birks, H. J.; and Hall, R. I.\n\n\n \n\n\n\n The Holocene, 12(4): 481–496. May 2002.\n \n\n\n\n
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\n\n\n@article{bigler_quantitative_2002,\n\ttitle = {Quantitative multiproxy assessment of long-term patterns of {Holocene} environmental change from a small lake near {Abisko}, northern {Sweden}},\n\tvolume = {12},\n\tissn = {0959-6836},\n\turl = {http://journals.sagepub.com/doi/abs/10.1191/0959683602hl559rp},\n\tdoi = {10.1191/0959683602hl559rp},\n\tabstract = {Quantitative reconstructions are made of Holocene changes in climatic and environmental conditions from analyses of pollen, chironomids and diatoms in identical stratigraphic levels of a sediment core from Vuoskkujávri (68°20'43 N, 19°06'00 E, 348 m a.s.l.) near Abisko in northern Sweden (Lapland). Transfer functions, based on regional calibration sets, are applied to reconstruct Holocene patterns in mean July air temperature (using all three indicators), mean January air temperature (pollen), annual precipitation (pollen) and lakewater pH (diatoms). During periods with ‘good’ fit to the modern calibration sets all mean July air-temperature inferences based on the three proxy indicators reveal a general trend of decreasing temperature: pollen-inferred mean July air temperature shows a decrease of c. 1.1°C since 7500 cal. yrs BP; the chironomids show a decrease of c. 1.2°C since the early Holocene; whereas the diatoms show a decrease of c. 1.5°C since 6000 cal. yrs BP. Pollen-inferred mean January air temperature indicates that winters may have been warmer by c. 3.0°C during the early Holocene, followed by a gradual cooling until 8500 cal. yrs BP (c. 1.0°C warmer than today) and a subsequent warming until 7000 cal. yrs BP (c. 2.0°C warmer than today). Since 7000 cal. yrs BP, a gradual cooling towards the present-day values is inferred. According to the pollen, annual precipitation may have been considerably higher during the early Holocene than today (c. +150 mm) and increased until 7000 cal. yrs BP (c. +320 mm). Since 7000 cal. yrs BP, annual precipitation decreased continuously towards present-day values. Diatom-inferred pH trends show that natural acidification of c. 0.5 pH units followed deglaciation; present-day values were reached c. 5000 cal. yrs BP. The early Holocene is identified as a problematic time period for the application of modern calibration sets, as diatoms show ‘poor’ fit to the calibration set from 10 600 to 6000 cal. yrs BP, pollen from 10 600 to 7500 cal. yrs BP, and chironomids from 10 250 to 10 000 cal. yrs BP. Compared with estimates from the COHMAP GCM model, mean July air-temperature inferences based on biological proxies at Vuoskkujávri suggest a more moderate decrease in temperature over the past 9000 years.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-07},\n\tjournal = {The Holocene},\n\tauthor = {Bigler, Christian and Larocque, Isabelle and Peglar, Sylvia M. and Birks, H. J.B. and Hall, Roland I.},\n\tmonth = may,\n\tyear = {2002},\n\tkeywords = {\\#nosource, Holocene, Lapland, Pollen, chironomids, diatoms, multiproxy approach, pH, precipitation, quantitative inferences, subarctic, temperature, weighted averaging partial least squares (WA-PLS)},\n\tpages = {481--496},\n}\n\n\n\n\n\n Quantitative reconstructions are made of Holocene changes in climatic and environmental conditions from analyses of pollen, chironomids and diatoms in identical stratigraphic levels of a sediment core from Vuoskkujávri (68°20'43 N, 19°06'00 E, 348 m a.s.l.) near Abisko in northern Sweden (Lapland). Transfer functions, based on regional calibration sets, are applied to reconstruct Holocene patterns in mean July air temperature (using all three indicators), mean January air temperature (pollen), annual precipitation (pollen) and lakewater pH (diatoms). During periods with ‘good’ fit to the modern calibration sets all mean July air-temperature inferences based on the three proxy indicators reveal a general trend of decreasing temperature: pollen-inferred mean July air temperature shows a decrease of c. 1.1°C since 7500 cal. yrs BP; the chironomids show a decrease of c. 1.2°C since the early Holocene; whereas the diatoms show a decrease of c. 1.5°C since 6000 cal. yrs BP. Pollen-inferred mean January air temperature indicates that winters may have been warmer by c. 3.0°C during the early Holocene, followed by a gradual cooling until 8500 cal. yrs BP (c. 1.0°C warmer than today) and a subsequent warming until 7000 cal. yrs BP (c. 2.0°C warmer than today). Since 7000 cal. yrs BP, a gradual cooling towards the present-day values is inferred. According to the pollen, annual precipitation may have been considerably higher during the early Holocene than today (c. +150 mm) and increased until 7000 cal. yrs BP (c. +320 mm). Since 7000 cal. yrs BP, annual precipitation decreased continuously towards present-day values. Diatom-inferred pH trends show that natural acidification of c. 0.5 pH units followed deglaciation; present-day values were reached c. 5000 cal. yrs BP. The early Holocene is identified as a problematic time period for the application of modern calibration sets, as diatoms show ‘poor’ fit to the calibration set from 10 600 to 6000 cal. yrs BP, pollen from 10 600 to 7500 cal. yrs BP, and chironomids from 10 250 to 10 000 cal. yrs BP. Compared with estimates from the COHMAP GCM model, mean July air-temperature inferences based on biological proxies at Vuoskkujávri suggest a more moderate decrease in temperature over the past 9000 years.\n
\n\n\n\n \n\n \n \n \n \n \n \n Diatoms as indicators of climatic and limnological change in Swedish Lapland: a 100-lake calibration set and its validation for paleoecological reconstructions.\n \n \n \n \n\n\n \n Bigler, C.; and Hall, R. I.\n\n\n \n\n\n\n Journal of Paleolimnology, 27(1): 97–115. January 2002.\n \n\n\n\n
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\n\n\n@article{bigler_diatoms_2002,\n\ttitle = {Diatoms as indicators of climatic and limnological change in {Swedish} {Lapland}: a 100-lake calibration set and its validation for paleoecological reconstructions},\n\tvolume = {27},\n\tissn = {0921-2728, 1573-0417},\n\tshorttitle = {Diatoms as indicators of climatic and limnological change in {Swedish} {Lapland}},\n\turl = {http://link.springer.com/article/10.1023/A:1013562325326},\n\tdoi = {10.1023/A:1013562325326},\n\tabstract = {This study investigated the distribution of subfossil diatom assemblages in surficial sediments of 100 lakes along steep ecological and climatic gradients in northernmost Sweden (Abisko region, 67.07° N to 68.48° N latitude, 17.67° E to 23.52° E longitude) to develop and cross-validate transfer functions for paleoenvironmental reconstruction. Of 19 environmental variables determined for each site, 15 were included in the statistical analysis. Lake-water pH (8.0\\%), sedimentary loss-on-ignition (LOI, 5.9\\% and estimated mean July air temperature (July T, 4.8\\%) explained the greatest amounts of variation in the distribution of diatom taxa among the 100 lakes. Temperature and pH optima and tolerances were calculated for abundant taxa. Transfer functions, based on WA-PLS (weighted averaging partial least squares), were developed for pH (r2 = 0.77, root-mean-square-error of prediction (RMSEP) = 0.19 pH units, maximum bias = 0.31, as assessed by leave-one-out cross-validation) based on 99 lakes and for July T (r2 = 0.75, RMSEP = 0.96 °C, max. bias = 1.37 °C) based on the full 100 lake set. We subsequently assessed the ability of the diatom transfer functions to estimate lake-water pH and July T using a form of independent cross-validation. To do this, the 100-lake set was divided in two subsets. An 85-lake training-set (based on single limnological measurements) was used to develop transfer functions with similar performance as those based on the full 100 lakes, and a 15-lake test-set (with 2 years of monthly limnological measurements throughout the ice-free seasons) was used to test the transfer functions developed from the 85-lake training-set. Results from the intra-set cross-validation exercise demonstrated that lake-specific prediction errors (RMSEP) for the 15-lake test-set corresponded closely with the median measured values (pH) and the estimations based on spatial interpolations of data from weather stations (July T). The prediction errors associated with diatom inferences were usually within the range of seasonal and interannual variability. Overall, our results confirm that diatoms can provide reliable and robust estimates of lake-water pH and July T, that WA-PLS is a robust calibration method and that long-term environmental data are needed for further improvement of paleolimnological transfer functions.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Bigler, Christian and Hall, Roland I.},\n\tmonth = jan,\n\tyear = {2002},\n\tkeywords = {\\#nosource, Hydrobiology, Lake sediments, Northern Fennoscandia, Physical Geography, Sedimentology, abisko, climate change, diatoms, intra-set cross-validation, pH, temperature, training-set, transfer functions, weighted averaging partial least squares regression (WA-PLS)},\n\tpages = {97--115},\n}\n\n\n\n\n\n This study investigated the distribution of subfossil diatom assemblages in surficial sediments of 100 lakes along steep ecological and climatic gradients in northernmost Sweden (Abisko region, 67.07° N to 68.48° N latitude, 17.67° E to 23.52° E longitude) to develop and cross-validate transfer functions for paleoenvironmental reconstruction. Of 19 environmental variables determined for each site, 15 were included in the statistical analysis. Lake-water pH (8.0%), sedimentary loss-on-ignition (LOI, 5.9% and estimated mean July air temperature (July T, 4.8%) explained the greatest amounts of variation in the distribution of diatom taxa among the 100 lakes. Temperature and pH optima and tolerances were calculated for abundant taxa. Transfer functions, based on WA-PLS (weighted averaging partial least squares), were developed for pH (r2 = 0.77, root-mean-square-error of prediction (RMSEP) = 0.19 pH units, maximum bias = 0.31, as assessed by leave-one-out cross-validation) based on 99 lakes and for July T (r2 = 0.75, RMSEP = 0.96 °C, max. bias = 1.37 °C) based on the full 100 lake set. We subsequently assessed the ability of the diatom transfer functions to estimate lake-water pH and July T using a form of independent cross-validation. To do this, the 100-lake set was divided in two subsets. An 85-lake training-set (based on single limnological measurements) was used to develop transfer functions with similar performance as those based on the full 100 lakes, and a 15-lake test-set (with 2 years of monthly limnological measurements throughout the ice-free seasons) was used to test the transfer functions developed from the 85-lake training-set. Results from the intra-set cross-validation exercise demonstrated that lake-specific prediction errors (RMSEP) for the 15-lake test-set corresponded closely with the median measured values (pH) and the estimations based on spatial interpolations of data from weather stations (July T). The prediction errors associated with diatom inferences were usually within the range of seasonal and interannual variability. Overall, our results confirm that diatoms can provide reliable and robust estimates of lake-water pH and July T, that WA-PLS is a robust calibration method and that long-term environmental data are needed for further improvement of paleolimnological transfer functions.\n
\n\n\n\n \n\n \n \n \n \n \n \n A 7400-year tree-ring chronology in northern Swedish Lapland: natural climatic variability expressed on annual to millennial timescales.\n \n \n \n \n\n\n \n Grudd, H.; Briffa, K. R.; Karlén, W.; Bartholin, T. S.; Jones, P. D.; and Kromer, B.\n\n\n \n\n\n\n The Holocene, 12(6): 657–665. September 2002.\n 00344\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{grudd_7400-year_2002,\n\ttitle = {A 7400-year tree-ring chronology in northern {Swedish} {Lapland}: natural climatic variability expressed on annual to millennial timescales},\n\tvolume = {12},\n\tissn = {0959-6836, 1477-0911},\n\tshorttitle = {A 7400-year tree-ring chronology in northern {Swedish} {Lapland}},\n\turl = {http://hol.sagepub.com.proxy.ub.umu.se/content/12/6/657},\n\tdoi = {10.1191/0959683602hl578rp},\n\tabstract = {Tree-ring widths from 880 living, dry dead, and subfossil northern Swedish pines (Pinus syl vestris L.) have been assembled into a continuous and precisely dated chronology (the Torneträsk chronology) covering the period 5407 BC to ad 1997. Biological trends in the data were removed with autoregressive standardization (ARS) to emphasize year-to-year variability, and with regional curve stan dardization (RCS) to emphasize variability on timescales from decades to centuries. The strong association with summer mean temperature (June–August) has enabled the production of a temperature reconstruction for the last 7400 years, providing information on natural summer-temperature variability on timescales from years to centuries. Numerous cold episodes, comparable in severity and duration to the severe summers of the seventeenth century, are shown throughout the last seven millennia. Particularly severe conditions suggested between 600 and 1 BC correspond to a known period of glacier expansion. The relatively warm conditions of the late twentieth century do not exceed those reconstructed for several earlier time intervals, although replication is relatively poor and confidence in the reconstructions is correspondingly reduced in the pre-Christian period, particularly around 3000, 1600 and 330 bc. Despite the use of the RCS approach in chronology construction, the 7400-year chronology does not express the full range of millennial-timescale temperature change in northern Sweden.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2015-10-04},\n\tjournal = {The Holocene},\n\tauthor = {Grudd, Håkan and Briffa, Keith R. and Karlén, Wibjorn and Bartholin, Thomas S. and Jones, Philip D. and Kromer, Bernd},\n\tmonth = sep,\n\tyear = {2002},\n\tnote = {00344},\n\tkeywords = {\\#nosource, Dendroclimatology, Holocene, Pinus sylvestris, climate, northern Scandinavia, summer temperature, tree rings},\n\tpages = {657--665},\n}\n\n\n\n\n\n Tree-ring widths from 880 living, dry dead, and subfossil northern Swedish pines (Pinus syl vestris L.) have been assembled into a continuous and precisely dated chronology (the Torneträsk chronology) covering the period 5407 BC to ad 1997. Biological trends in the data were removed with autoregressive standardization (ARS) to emphasize year-to-year variability, and with regional curve stan dardization (RCS) to emphasize variability on timescales from decades to centuries. The strong association with summer mean temperature (June–August) has enabled the production of a temperature reconstruction for the last 7400 years, providing information on natural summer-temperature variability on timescales from years to centuries. Numerous cold episodes, comparable in severity and duration to the severe summers of the seventeenth century, are shown throughout the last seven millennia. Particularly severe conditions suggested between 600 and 1 BC correspond to a known period of glacier expansion. The relatively warm conditions of the late twentieth century do not exceed those reconstructed for several earlier time intervals, although replication is relatively poor and confidence in the reconstructions is correspondingly reduced in the pre-Christian period, particularly around 3000, 1600 and 330 bc. Despite the use of the RCS approach in chronology construction, the 7400-year chronology does not express the full range of millennial-timescale temperature change in northern Sweden.\n
\n\n\n\n \n\n \n \n \n \n \n \n Photochemical and microbial processing of stream and soil water dissolved organic matter in a boreal forested catchment in northern Sweden.\n \n \n \n \n\n\n \n Köhler, S.; Buffam, I.; Jonsson, A.; and Bishop, K.\n\n\n \n\n\n\n Aquatic Sciences, 64(3): 269–281. October 2002.\n 00084\n\n\n\n
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\n\n\n@article{kohler_photochemical_2002,\n\ttitle = {Photochemical and microbial processing of stream and soil water dissolved organic matter in a boreal forested catchment in northern {Sweden}},\n\tvolume = {64},\n\tissn = {1015-1621, 1420-9055},\n\turl = {http://link.springer.com/article/10.1007/s00027-002-8071-z},\n\tdoi = {10.1007/s00027-002-8071-z},\n\tabstract = {. Natural organic matter (NOM) from stream and soil water in a humic-rich headwater catchment in northern Sweden (initial total organic carbon (TOC) concentrations 10-40 mg C L–1) was rapidly degraded by light and microbial activity in an incubation experiment. Concentration losses were 33–50\\% after 12 days of exposure to 69 W m–2 artificial PAR and 16 W m–2 UV radiation. Natural, unshaded mid-day solar radiation in the region (68°N 18°E) during the month of june is 159 W m–2 for PAR. In contrast to microbial organic carbon removal, TOC exponentially decreased upon radiation, which suggests that TOC is more rapidly oxidized by light than by ambient microbes. Further, rapid decline in TOC concentration implies the presence of a dominant pool of photo-labile compounds (p {\\textgreater} 95\\%). A measured mass balance for carbon identified 50–75\\% of the degraded TOC as carbon dioxide after 12 days of exposure to light. The observed conversion of organic to inorganic carbon was accompanied by increases in pH and alkalinity, suggesting that photo-degradation of NOM potentially contributes to in-stream buffering capacity. The remaining refractory TOC changed in chemical character, including an altered molecular weight distribution with decreased average weight and a change in the proportions of humics as evidenced by absorbance ratios (A254/A420). Extrapolation of the experiment to natural headwater conditions show that photo-degradation is an important in-stream process that should be considered in calculations of carbon turnover in surface waters because of its influence on both TOC amount and character.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-08},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Köhler, Stephan and Buffam, Ishi and Jonsson, Anders and Bishop, Kevin},\n\tmonth = oct,\n\tyear = {2002},\n\tnote = {00084},\n\tkeywords = {\\#nosource, Photo-degradation, carbon dioxide, dissolved organic matter (DOM), headwaters, natrual organic matter (NOM)},\n\tpages = {269--281},\n}\n\n\n\n\n\n . Natural organic matter (NOM) from stream and soil water in a humic-rich headwater catchment in northern Sweden (initial total organic carbon (TOC) concentrations 10-40 mg C L–1) was rapidly degraded by light and microbial activity in an incubation experiment. Concentration losses were 33–50% after 12 days of exposure to 69 W m–2 artificial PAR and 16 W m–2 UV radiation. Natural, unshaded mid-day solar radiation in the region (68°N 18°E) during the month of june is 159 W m–2 for PAR. In contrast to microbial organic carbon removal, TOC exponentially decreased upon radiation, which suggests that TOC is more rapidly oxidized by light than by ambient microbes. Further, rapid decline in TOC concentration implies the presence of a dominant pool of photo-labile compounds (p \\textgreater 95%). A measured mass balance for carbon identified 50–75% of the degraded TOC as carbon dioxide after 12 days of exposure to light. The observed conversion of organic to inorganic carbon was accompanied by increases in pH and alkalinity, suggesting that photo-degradation of NOM potentially contributes to in-stream buffering capacity. The remaining refractory TOC changed in chemical character, including an altered molecular weight distribution with decreased average weight and a change in the proportions of humics as evidenced by absorbance ratios (A254/A420). Extrapolation of the experiment to natural headwater conditions show that photo-degradation is an important in-stream process that should be considered in calculations of carbon turnover in surface waters because of its influence on both TOC amount and character.\n
\n\n\n\n \n\n \n \n \n \n \n \n Foraging and movement paths of female reindeer: insights from fractal analysis, correlated random walks, and Lévy flights.\n \n \n \n \n\n\n \n Mårell, A.; Ball, J. P; and Hofgaard, A.\n\n\n \n\n\n\n Canadian Journal of Zoology, 80(5): 854–865. May 2002.\n 00195\n\n\n\n
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\n\n\n@article{marell_foraging_2002,\n\ttitle = {Foraging and movement paths of female reindeer: insights from fractal analysis, correlated random walks, and {Lévy} flights},\n\tvolume = {80},\n\tissn = {0008-4301, 1480-3283},\n\tshorttitle = {Foraging and movement paths of female reindeer},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/z02-061},\n\tdoi = {10.1139/z02-061},\n\tabstract = {00188},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2016-11-08},\n\tjournal = {Canadian Journal of Zoology},\n\tauthor = {Mårell, Anders and Ball, John P and Hofgaard, Annika},\n\tmonth = may,\n\tyear = {2002},\n\tnote = {00195},\n\tkeywords = {\\#nosource},\n\tpages = {854--865},\n}\n\n\n\n\n\n 00188\n
\n\n\n\n \n\n \n \n \n \n \n \n Postglacial paleoecology and inferred paleoclimate in the Engelmann spruce–subalpine fir forest of south-central British Columbia, Canada.\n \n \n \n \n\n\n \n Heinrichs, M. L; Hebda, R. J; Walker, I. R; and Palmer, S. L\n\n\n \n\n\n\n Palaeogeography, Palaeoclimatology, Palaeoecology, 184(3): 347–369. August 2002.\n 00019\n\n\n\n
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\n\n\n@article{heinrichs_postglacial_2002,\n\ttitle = {Postglacial paleoecology and inferred paleoclimate in the {Engelmann} spruce–subalpine fir forest of south-central {British} {Columbia}, {Canada}},\n\tvolume = {184},\n\tissn = {0031-0182},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0031018202002742},\n\tdoi = {10.1016/S0031-0182(02)00274-2},\n\tabstract = {Pollen, charcoal, and plant macrofossil analyses reveal five postglacial vegetation periods at Crater Lake, Crater Mountain, British Columbia. The first period, beginning ca. 11 400 14C yr BP was characterized by Artemisia steppe-tundra. At 9700 14C yr BP, Pinus parkland developed, and by 6700 14C yr BP was replaced by fire-successional Pinus-dominated Engelmann spruce and subalpine fir forest (ESSF). At 3800 14C yr BP, Picea became a more important element of the forest, and modern forest structure and composition developed by 1600 14C yr BP. Comparison of the fossil vegetation and fossil midge data derived from several ESSF sites in the southern interior reveals (1) similar late-Pleistocene vegetation and climate at all sites, (2) three distinct Holocene climatic stages: warm/dry, warm/moist, and cool/moist, (3) confirmation of the warm/moist period as a distinct climatic period, and (4) distinct differences in Holocene vegetation change among the sites. The driest and warmest site was most sensitive to climatic change, whereas cooler, moister sites were less sensitive. The present east–west climate gradient originated with postglacial warming at the beginning of the Holocene. Vegetation response to climate change and natural disturbance in these sites is strongly controlled by local site characteristics. These characteristics may have implications for forest, environment, and resource management.},\n\tnumber = {3},\n\turldate = {2018-06-11},\n\tjournal = {Palaeogeography, Palaeoclimatology, Palaeoecology},\n\tauthor = {Heinrichs, Markus L and Hebda, Richard J and Walker, Ian R and Palmer, Samantha L},\n\tmonth = aug,\n\tyear = {2002},\n\tnote = {00019},\n\tkeywords = {\\#nosource, Okanagan, climate history, fire history, palynology, vegetation history},\n\tpages = {347--369},\n}\n\n\n\n\n\n Pollen, charcoal, and plant macrofossil analyses reveal five postglacial vegetation periods at Crater Lake, Crater Mountain, British Columbia. The first period, beginning ca. 11 400 14C yr BP was characterized by Artemisia steppe-tundra. At 9700 14C yr BP, Pinus parkland developed, and by 6700 14C yr BP was replaced by fire-successional Pinus-dominated Engelmann spruce and subalpine fir forest (ESSF). At 3800 14C yr BP, Picea became a more important element of the forest, and modern forest structure and composition developed by 1600 14C yr BP. Comparison of the fossil vegetation and fossil midge data derived from several ESSF sites in the southern interior reveals (1) similar late-Pleistocene vegetation and climate at all sites, (2) three distinct Holocene climatic stages: warm/dry, warm/moist, and cool/moist, (3) confirmation of the warm/moist period as a distinct climatic period, and (4) distinct differences in Holocene vegetation change among the sites. The driest and warmest site was most sensitive to climatic change, whereas cooler, moister sites were less sensitive. The present east–west climate gradient originated with postglacial warming at the beginning of the Holocene. Vegetation response to climate change and natural disturbance in these sites is strongly controlled by local site characteristics. These characteristics may have implications for forest, environment, and resource management.\n
\n\n\n\n \n\n \n \n \n \n \n \n Shifts in radial growth responses of coastal Picea abies induced by climatic change during the 20th century, central Norway.\n \n \n \n \n\n\n \n Solberg, B.; Hofgaard, A.; and Hytteborn, H.\n\n\n \n\n\n\n Écoscience, 9(1): 79–88. January 2002.\n 00054\n\n\n\n
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\n\n\n@article{solberg_shifts_2002,\n\ttitle = {Shifts in radial growth responses of coastal {Picea} abies induced by climatic change during the 20th century, central {Norway}},\n\tvolume = {9},\n\tissn = {1195-6860},\n\turl = {https://doi.org/10.1080/11956860.2002.11682693},\n\tdoi = {10.1080/11956860.2002.11682693},\n\tabstract = {Climate-growth relationships since the end of the 19th century were analysed by using regional climate data and North Atlantic Oscillation index data, together with spruce (Picea abies (L) Karst.) tree-ring data from an altitudinal gradient close to the coast in central Norway (64°N). Correlation and response function analyses were used to decipher both spatial and temporal diameter growth responses. A positive response for May and June temperatures dominated along the entire gradient, but the importance of individual months shifted through time. In periods when May and June temperatures were above their long-term means, the importance of other climate factors increased. Winter climate was significantly related to radial tree growth mainly for periods up to the 1940s, but not during the second half of the 20th century. This pattern was principally caused by changes in the response to winter precipitation. The summer climate acquired increased importance in periods with warm and moist winters. The climate-growth relationship in this study changed continuously and dynamically during the studied period; this might be a general phenomenon that should be carefully considered in dendroclimatological studies. In scenarios for forest development, it is of vital importance to build on detailed knowledge of growth responses to multiple climate variables for all seasons, particularly where the oceanic influence is predicted to be spatially extended.},\n\tnumber = {1},\n\turldate = {2018-06-11},\n\tjournal = {Écoscience},\n\tauthor = {Solberg, Bård and Hofgaard, Annika and Hytteborn, Håkan},\n\tmonth = jan,\n\tyear = {2002},\n\tnote = {00054},\n\tkeywords = {\\#nosource, Changements climatiques, Climate change, Dendroclimatologie, Edndroclimatology, Impact océanique, NAO, Oceanic impact, Oscillation nord-atlantique, Picea abies, Réponse de la croissance des arbres, Tree growth response},\n\tpages = {79--88},\n}\n\n\n\n\n\n Climate-growth relationships since the end of the 19th century were analysed by using regional climate data and North Atlantic Oscillation index data, together with spruce (Picea abies (L) Karst.) tree-ring data from an altitudinal gradient close to the coast in central Norway (64°N). Correlation and response function analyses were used to decipher both spatial and temporal diameter growth responses. A positive response for May and June temperatures dominated along the entire gradient, but the importance of individual months shifted through time. In periods when May and June temperatures were above their long-term means, the importance of other climate factors increased. Winter climate was significantly related to radial tree growth mainly for periods up to the 1940s, but not during the second half of the 20th century. This pattern was principally caused by changes in the response to winter precipitation. The summer climate acquired increased importance in periods with warm and moist winters. The climate-growth relationship in this study changed continuously and dynamically during the studied period; this might be a general phenomenon that should be carefully considered in dendroclimatological studies. In scenarios for forest development, it is of vital importance to build on detailed knowledge of growth responses to multiple climate variables for all seasons, particularly where the oceanic influence is predicted to be spatially extended.\n
\n\n\n\n \n\n \n \n \n \n \n \n Plant distribution pattern across the forest-tundra ecotone: The importance of treeline position.\n \n \n \n \n\n\n \n Hofgaard, A.; and Wilmann, B.\n\n\n \n\n\n\n Écoscience, 9(3): 375–385. January 2002.\n 00037\n\n\n\n
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\n\n\n@article{hofgaard_plant_2002,\n\ttitle = {Plant distribution pattern across the forest-tundra ecotone: {The} importance of treeline position},\n\tvolume = {9},\n\tissn = {1195-6860},\n\tshorttitle = {Plant distribution pattern across the forest-tundra ecotone},\n\turl = {https://doi.org/10.1080/11956860.2002.11682725},\n\tdoi = {10.1080/11956860.2002.11682725},\n\tabstract = {The relationship between treeline position and field-layer diversity in the central Norwegian Mountains is examined by the use of multivariate techniques. Species and environmental data from altitudinal transects across the entire forest-tundra ecotone and various altitudinal partitions are analysed. The main variation in the species data show positive correspondence with altitude and distance to treeline and forest line and negative correspondence with factors related to the structure and presence of a tree cover. Distance to the treeline explained most of the variance in species distribution and most distribution boundaries are found in the vicinity of the treeline. Topography is an apparent factor only in a zone just above the treeline, and there is no correspondence between species occurrence and altitude in this zone. The importance of aspect is only evident at high altitudes, where plant communities are most exposed to abiotic environmental factors. Descending tree communities during the Holocene have produced plant communities above the present treeline that still are dependent on environmental conditions previously provided by the forest. Under present alpine conditions the main structuring force for vegetation composition is changed from being mainly biotic to abiotic. The long-term inertia of the field-layer composition across the forest-tundra ecotone is important to consider when making predictions of future responses of the ecotone.},\n\tnumber = {3},\n\turldate = {2018-06-11},\n\tjournal = {Écoscience},\n\tauthor = {Hofgaard, Annika and Wilmann, Bodil},\n\tmonth = jan,\n\tyear = {2002},\n\tnote = {00037},\n\tkeywords = {\\#nosource, Analyses d’ordination, Central Norway, Centre de la Norvège, Cmémoire écologique, Composition en espèces, Dynamique de la limite des arbres, Ecological memory, Holocene, Holocène, Ordination analyses, Species composition, Treeline dynamics},\n\tpages = {375--385},\n}\n\n\n\n\n\n The relationship between treeline position and field-layer diversity in the central Norwegian Mountains is examined by the use of multivariate techniques. Species and environmental data from altitudinal transects across the entire forest-tundra ecotone and various altitudinal partitions are analysed. The main variation in the species data show positive correspondence with altitude and distance to treeline and forest line and negative correspondence with factors related to the structure and presence of a tree cover. Distance to the treeline explained most of the variance in species distribution and most distribution boundaries are found in the vicinity of the treeline. Topography is an apparent factor only in a zone just above the treeline, and there is no correspondence between species occurrence and altitude in this zone. The importance of aspect is only evident at high altitudes, where plant communities are most exposed to abiotic environmental factors. Descending tree communities during the Holocene have produced plant communities above the present treeline that still are dependent on environmental conditions previously provided by the forest. Under present alpine conditions the main structuring force for vegetation composition is changed from being mainly biotic to abiotic. The long-term inertia of the field-layer composition across the forest-tundra ecotone is important to consider when making predictions of future responses of the ecotone.\n
\n\n\n\n \n\n \n \n \n \n \n \n Peatland pines as climate indicators? A regional comparison of the climatic influence on Scots pine growth in Sweden.\n \n \n \n \n\n\n \n Linderholm, H. W; Moberg, A.; and Grudd, H.\n\n\n \n\n\n\n Canadian Journal of Forest Research, 32(8): 1400–1410. August 2002.\n 00069\n\n\n\n
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\n\n\n@article{linderholm_peatland_2002,\n\ttitle = {Peatland pines as climate indicators? {A} regional comparison of the climatic influence on {Scots} pine growth in {Sweden}},\n\tvolume = {32},\n\tissn = {0045-5067},\n\tshorttitle = {Peatland pines as climate indicators?},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/x02-071},\n\tdoi = {10.1139/x02-071},\n\tabstract = {Six tree-ring chronologies from Sweden were analyzed to assess if Scots pine (Pinus sylvestris L.) growing on peatlands are useful as annually resolved climate indicators. Also, climategrowth relationships were compared with those of pines growing on nearby dry sites to evaluate if pines from both environments may be combined to yield climate information. While temperatures in spring and summer had positive influences on peatland pine growth, precipitation responses ranged from negative in the north to positive in the south. Climate growth response patterns differed between peatland and neighboring dry sites, where climatic information in peatland pines was weaker. Added to the direct effect of growth-year climate, is the response of peatland pines to water table variations, a function of climate over several years, likely causing annual growth to reflect a synthesis of climate over a long period. Scots pine climate growth responses, in both environments, changed throughout the 20th century, correspo..., Six séries dendrochronologiques originaires de Suède ont été analysées pour déterminer si le pin sylvestre (Pinus sylvestris L.) croissant dans des tourbières pouvait servir d'indicateur du climat annuel. Les relations entre le climat et la croissance ont aussi été comparées avec celles de pins croissant à proximité sur des sites secs pour évaluer si les pins des deux types d'environnement peuvent être combinés pour fournir de l'information sur le climat. Alors que les températures du printemps et de l'été ont une influence positive sur la croissance des pins de tourbière, les réponses aux précipitations varient de négatives au nord à positives au sud. Les patrons de réponse de la croissance au climat diffèrent entre les tourbières et les sites secs voisins et l'information sur le climat extraite des pins de tourbière est plus réduite. À la réponse des pins de tourbière à l'effet direct du climat annuel sur la croissance, s'ajoute celle à la variation du niveau de la nappe phréatique, qui est fonction du ...},\n\tnumber = {8},\n\turldate = {2018-06-11},\n\tjournal = {Canadian Journal of Forest Research},\n\tauthor = {Linderholm, Hans W and Moberg, Anders and Grudd, Håkan},\n\tmonth = aug,\n\tyear = {2002},\n\tnote = {00069},\n\tkeywords = {\\#nosource},\n\tpages = {1400--1410},\n}\n\n\n\n\n\n Six tree-ring chronologies from Sweden were analyzed to assess if Scots pine (Pinus sylvestris L.) growing on peatlands are useful as annually resolved climate indicators. Also, climategrowth relationships were compared with those of pines growing on nearby dry sites to evaluate if pines from both environments may be combined to yield climate information. While temperatures in spring and summer had positive influences on peatland pine growth, precipitation responses ranged from negative in the north to positive in the south. Climate growth response patterns differed between peatland and neighboring dry sites, where climatic information in peatland pines was weaker. Added to the direct effect of growth-year climate, is the response of peatland pines to water table variations, a function of climate over several years, likely causing annual growth to reflect a synthesis of climate over a long period. Scots pine climate growth responses, in both environments, changed throughout the 20th century, correspo..., Six séries dendrochronologiques originaires de Suède ont été analysées pour déterminer si le pin sylvestre (Pinus sylvestris L.) croissant dans des tourbières pouvait servir d'indicateur du climat annuel. Les relations entre le climat et la croissance ont aussi été comparées avec celles de pins croissant à proximité sur des sites secs pour évaluer si les pins des deux types d'environnement peuvent être combinés pour fournir de l'information sur le climat. Alors que les températures du printemps et de l'été ont une influence positive sur la croissance des pins de tourbière, les réponses aux précipitations varient de négatives au nord à positives au sud. Les patrons de réponse de la croissance au climat diffèrent entre les tourbières et les sites secs voisins et l'information sur le climat extraite des pins de tourbière est plus réduite. À la réponse des pins de tourbière à l'effet direct du climat annuel sur la croissance, s'ajoute celle à la variation du niveau de la nappe phréatique, qui est fonction du ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Twentieth-Century Scots Pine Growth Variations in the Central Scandinavian Mountains Related to Climate Change.\n \n \n \n \n\n\n \n Linderholm, H. W.\n\n\n \n\n\n\n Arctic, Antarctic, and Alpine Research, 34(4): 440–449. 2002.\n 00039\n\n\n\n
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\n\n\n@article{linderholm_twentieth-century_2002,\n\ttitle = {Twentieth-{Century} {Scots} {Pine} {Growth} {Variations} in the {Central} {Scandinavian} {Mountains} {Related} to {Climate} {Change}},\n\tvolume = {34},\n\tissn = {1523-0430},\n\turl = {http://www.jstor.org/stable/1552202},\n\tdoi = {10.2307/1552202},\n\tabstract = {Climate-sensitive trees are valuable for reconstructing past climates, but they also can be used to assess the impacts of environmental change, such as global warming, on forest ecosystems. Growth variability and growth responses to climate of a Scots pine (Pinus sylvestris L.) tree-ring width chronology, from the treeline in the central Scandinavian Mountains, were studied throughout the 20th century. Summer temperatures, especially in July, were the most influential climate factor for tree growth. Correlation analyses in three 30-yr periods showed that growth responses to climate varied through time, being particularly low in 1931 to 1960. Nevertheless, tree growth around 1950 was the highest for 320 yr, implying optimal growth conditions. This growth increase appears to be a response to increased summer temperatures, a lengthening of the growing season, and a temporal change in the atmospheric circulation pattern. Despite a continuation of seemingly favorable growth conditions in the latter half of the 20th century, pine growth decreased after the 1950s. It appears that high-altitude pine experienced stress that surpassed the positive effect of improved growth season climate. Since pine growth decline coincided with an unprecedented strong and positive period of wintertime North Atlantic Oscillation (NAO), a measure of strength of westerly winds bringing mild and moist air masses over Scandinavia, it is proposed that milder and wetter winters caused growth stress, and hence reduced growth, in high-altitude central Sweden.},\n\tnumber = {4},\n\turldate = {2018-06-11},\n\tjournal = {Arctic, Antarctic, and Alpine Research},\n\tauthor = {Linderholm, Hans W.},\n\tyear = {2002},\n\tnote = {00039},\n\tkeywords = {\\#nosource},\n\tpages = {440--449},\n}\n\n\n\n\n\n Climate-sensitive trees are valuable for reconstructing past climates, but they also can be used to assess the impacts of environmental change, such as global warming, on forest ecosystems. Growth variability and growth responses to climate of a Scots pine (Pinus sylvestris L.) tree-ring width chronology, from the treeline in the central Scandinavian Mountains, were studied throughout the 20th century. Summer temperatures, especially in July, were the most influential climate factor for tree growth. Correlation analyses in three 30-yr periods showed that growth responses to climate varied through time, being particularly low in 1931 to 1960. Nevertheless, tree growth around 1950 was the highest for 320 yr, implying optimal growth conditions. This growth increase appears to be a response to increased summer temperatures, a lengthening of the growing season, and a temporal change in the atmospheric circulation pattern. Despite a continuation of seemingly favorable growth conditions in the latter half of the 20th century, pine growth decreased after the 1950s. It appears that high-altitude pine experienced stress that surpassed the positive effect of improved growth season climate. Since pine growth decline coincided with an unprecedented strong and positive period of wintertime North Atlantic Oscillation (NAO), a measure of strength of westerly winds bringing mild and moist air masses over Scandinavia, it is proposed that milder and wetter winters caused growth stress, and hence reduced growth, in high-altitude central Sweden.\n
\n\n\n\n \n\n \n \n \n \n \n \n Similar Relationships Between Pelagic Primary and Bacterial Production in Clearwater and Humic Lakes.\n \n \n \n \n\n\n \n Karlsson, J.; Jansson, M.; and Jonsson, A.\n\n\n \n\n\n\n Ecology, 83(10): 2902–2910. October 2002.\n \n\n\n\n
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\n\n\n@article{karlsson_similar_2002,\n\ttitle = {Similar {Relationships} {Between} {Pelagic} {Primary} and {Bacterial} {Production} in {Clearwater} and {Humic} {Lakes}},\n\tvolume = {83},\n\tissn = {1939-9170},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1890/0012-9658(2002)083[2902:SRBPPA]2.0.CO;2/abstract},\n\tdoi = {10.1890/0012-9658(2002)083[2902:SRBPPA]2.0.CO;2},\n\tabstract = {We examined the relationship between planktonic primary production (PP) and bacterial production (BP) in 16 subarctic lakes along an altitude gradient extending from colored coniferous forest lakes to clearwater high alpine lakes. We tested the hypothesis that there was a shift from low to high PP:BP ratios along this gradient. The clearwater alpine lakes had low PP:BP ratios, generally well below 1.0, while the highest ratios were found in the forest lakes. In contradiction to our hypothesis, the pelagic systems of the clearwater lakes were thus dominated by bacterial energy mobilization from external carbon sources. In this respect the alpine lakes were similar to highly humic lakes. We suggest that the relationship between C, N, and P plays a critical role in determining the PP:BP ratio, and that the N:P ratio in particular can be critical for development of PP or BP dominance in the pelagic systems of unproductive lakes.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2017-02-06},\n\tjournal = {Ecology},\n\tauthor = {Karlsson, Jan and Jansson, Mats and Jonsson, Anders},\n\tmonth = oct,\n\tyear = {2002},\n\tkeywords = {\\#nosource, bacterioplankton production, dissolved organic carbon (DOC), lakes, nutrients, phytoplankton production, subarctic Sweden},\n\tpages = {2902--2910},\n}\n\n\n\n\n\n We examined the relationship between planktonic primary production (PP) and bacterial production (BP) in 16 subarctic lakes along an altitude gradient extending from colored coniferous forest lakes to clearwater high alpine lakes. We tested the hypothesis that there was a shift from low to high PP:BP ratios along this gradient. The clearwater alpine lakes had low PP:BP ratios, generally well below 1.0, while the highest ratios were found in the forest lakes. In contradiction to our hypothesis, the pelagic systems of the clearwater lakes were thus dominated by bacterial energy mobilization from external carbon sources. In this respect the alpine lakes were similar to highly humic lakes. We suggest that the relationship between C, N, and P plays a critical role in determining the PP:BP ratio, and that the N:P ratio in particular can be critical for development of PP or BP dominance in the pelagic systems of unproductive lakes.\n
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\n \n \n\n \n \n \n \n \n Whole-lake mineralization of allochthonous and autochthonous organic carbon in a large humic lake (Ortrasket, N. Sweden).\n \n \n \n\n\n \n Jonsson, A.; Meili, M.; Bergström, A.; and Jansson, M.\n\n\n \n\n\n\n Limnology and Oceanography, 46(7): 1691–1700. November 2001.\n \n\n\n\n
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\n\n\n@article{jonsson_whole-lake_2001,\n\ttitle = {Whole-lake mineralization of allochthonous and autochthonous organic carbon in a large humic lake ({Ortrasket}, {N}. {Sweden})},\n\tvolume = {46},\n\tissn = {0024-3590},\n\tdoi = {10.4319/lo.2001.46.7.1691},\n\tabstract = {Organic carbon mineralization was studied. in a large humic lake (Lake Ortrasket) in northern Sweden during a well-defined summer stratification period following high water flow during snowmelt. Several independent methods including plankton counts, measurements of bacterioplankton and phytoplankton production, stable isotope monitoring, sediment trapping, and mass balance calculations were used. Total organic carbon mineralization showed a summer mean of 0.3 g C m(-2) d(-1) and was partitioned about equally between water and sediment. In the water column, organic matter was mineralized by bacteria (60\\%) and protozoan and metazoan zooplankton (30\\%), as well as by photooxidation (10\\%). Most of the mineralized organic carbon was of allochthonous origin. Primary production in the lake contributed at most 5\\% of the total organic carbon input and about 20\\% of the total organic carbon mineralization. Total carbon mineralization in. the epilimnion and metalimnion agreed well with an estimate of CO2 evasion from the stratified lake, while CO2 accumulation in the hypolimnion matched the O-2 consumption and resulted in a very negative delta C-13 of DIC before autumn overturn (-23 parts per thousand). Isotopic compositions of DIC and POC confirmed the dominant influence of terrestrial organic input on the cycling of both organic and inorganic carbon in the lake.},\n\tlanguage = {English},\n\tnumber = {7},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Jonsson, A. and Meili, M. and Bergström, Ann-Kristin and Jansson, M.},\n\tmonth = nov,\n\tyear = {2001},\n\tkeywords = {\\#nosource, aquatic systems, bacterial production, dioxide, fresh, inorganic carbon, northern sweden, respiration, river, sedimentation, waters},\n\tpages = {1691--1700},\n}\n\n\n\n\n\n Organic carbon mineralization was studied. in a large humic lake (Lake Ortrasket) in northern Sweden during a well-defined summer stratification period following high water flow during snowmelt. Several independent methods including plankton counts, measurements of bacterioplankton and phytoplankton production, stable isotope monitoring, sediment trapping, and mass balance calculations were used. Total organic carbon mineralization showed a summer mean of 0.3 g C m(-2) d(-1) and was partitioned about equally between water and sediment. In the water column, organic matter was mineralized by bacteria (60%) and protozoan and metazoan zooplankton (30%), as well as by photooxidation (10%). Most of the mineralized organic carbon was of allochthonous origin. Primary production in the lake contributed at most 5% of the total organic carbon input and about 20% of the total organic carbon mineralization. Total carbon mineralization in. the epilimnion and metalimnion agreed well with an estimate of CO2 evasion from the stratified lake, while CO2 accumulation in the hypolimnion matched the O-2 consumption and resulted in a very negative delta C-13 of DIC before autumn overturn (-23 parts per thousand). Isotopic compositions of DIC and POC confirmed the dominant influence of terrestrial organic input on the cycling of both organic and inorganic carbon in the lake.\n
\n\n\n\n \n\n \n \n \n \n \n \n Pelagic Energy Mobilization and Carbon Dioxide Balance in Subarctic Lakes in Northern Sweden.\n \n \n \n \n\n\n \n Karlsson, J.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2001.\n Pages: 15\n\n\n\n
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\n\n\n\n@phdthesis{karlsson_pelagic_2001,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Pelagic {Energy} {Mobilization} and {Carbon} {Dioxide} {Balance} in {Subarctic} {Lakes} in {Northern} {Sweden}},\n\turl = {https://urn.kb.se/resolve?urn=urn:nbn:se:polar:diva-5948},\n\tlanguage = {eng},\n\turldate = {2023-07-21},\n\tschool = {Umeå University},\n\tauthor = {Karlsson, Jan},\n\tyear = {2001},\n\tnote = {Pages: 15},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Partial migration by large ungulates: characteristics of seasonal moose Alces alces ranges in northern Sweden.\n \n \n \n \n\n\n \n Ball, J. P.; Nordengren, C.; and Wallin, K.\n\n\n \n\n\n\n Wildlife Biology, 7(1): 39–47. January 2001.\n 00166\n\n\n\n
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\n\n\n@article{ball_partial_2001,\n\ttitle = {Partial migration by large ungulates: characteristics of seasonal moose {Alces} alces ranges in northern {Sweden}},\n\tvolume = {7},\n\tissn = {0909-6396},\n\tshorttitle = {Partial migration by large ungulates},\n\turl = {http://www.bioone.org/doi/abs/10.2981/wlb.2001.007},\n\tdoi = {10.2981/wlb.2001.007},\n\tabstract = {We studied seasonal migration of individually radio-collared moose Alces alces in a partially migrant population in northern Sweden. First, to investigate habitat selection at the level of individuals, we examined use vs availability of habitat characteristics within seasonal ranges. Second, to investigate what habitat characteristics migrants use to select these seasonal ranges, we contrasted the characteristics of summer and winter ranges of individual migrants. Third, to investigate why some moose migrate whereas others do not, we contrasted the snow conditions and the composition of the vegetation in the seasonal ranges of 36 migrant and 30 resident moose. At the level of habitat selection within a range, moose selected areas which had less mire, clear-cut and field habitats, as well as less snow. At the level of the entire range, migrants and residents had rather similar range compositions and differed only in migrants having less field habitats in their winter ranges; the proportion of Scots pine Pinus sylvestris stands, Norway spruce Picea abies stands, mire, deciduous, and clear-cut forest habitats did not differ, nor was there a difference in snow depth. Similarly, within the group of migrants, we detected no differences in habitat composition or snow depth between the summer ranges they just left, and the winter ranges they moved to. Snow quality (as indexed by the depths to which moose sank) did not differ between the two seasonal ranges of migrants, but calves sank less deeply in ranges of migrants than in ranges of residents, suggesting that snow quality may play a role in the selection of ranges by moose or their decision to migrate/remain resident. Thus, habitat composition and snow depth were important at lower levels of habitat selection, but differences among home ranges were not dramatic. The observation that snow quality differed significantly between ranges of residents and migrants suggests that future studies of migration might profitably investigate snow quality.},\n\tnumber = {1},\n\turldate = {2018-06-25},\n\tjournal = {Wildlife Biology},\n\tauthor = {Ball, John P. and Nordengren, Caroline and Wallin, Kjell},\n\tmonth = jan,\n\tyear = {2001},\n\tnote = {00166},\n\tkeywords = {\\#nosource},\n\tpages = {39--47},\n}\n\n\n\n\n\n We studied seasonal migration of individually radio-collared moose Alces alces in a partially migrant population in northern Sweden. First, to investigate habitat selection at the level of individuals, we examined use vs availability of habitat characteristics within seasonal ranges. Second, to investigate what habitat characteristics migrants use to select these seasonal ranges, we contrasted the characteristics of summer and winter ranges of individual migrants. Third, to investigate why some moose migrate whereas others do not, we contrasted the snow conditions and the composition of the vegetation in the seasonal ranges of 36 migrant and 30 resident moose. At the level of habitat selection within a range, moose selected areas which had less mire, clear-cut and field habitats, as well as less snow. At the level of the entire range, migrants and residents had rather similar range compositions and differed only in migrants having less field habitats in their winter ranges; the proportion of Scots pine Pinus sylvestris stands, Norway spruce Picea abies stands, mire, deciduous, and clear-cut forest habitats did not differ, nor was there a difference in snow depth. Similarly, within the group of migrants, we detected no differences in habitat composition or snow depth between the summer ranges they just left, and the winter ranges they moved to. Snow quality (as indexed by the depths to which moose sank) did not differ between the two seasonal ranges of migrants, but calves sank less deeply in ranges of migrants than in ranges of residents, suggesting that snow quality may play a role in the selection of ranges by moose or their decision to migrate/remain resident. Thus, habitat composition and snow depth were important at lower levels of habitat selection, but differences among home ranges were not dramatic. The observation that snow quality differed significantly between ranges of residents and migrants suggests that future studies of migration might profitably investigate snow quality.\n
\n\n\n\n \n\n \n \n \n \n \n \n Holocene climatic change in Swedish Lapland inferred from an oxygen-isotope record of lacustrine biogenic silica.\n \n \n \n \n\n\n \n Shemesh, A.; Rosqvist, G.; Rietti-Shati, M.; Rubensdotter, L.; Bigler, C.; Yam, R.; and Karlén, W.\n\n\n \n\n\n\n The Holocene, 11(4): 447–454. May 2001.\n 00095\n\n\n\n
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\n\n\n@article{shemesh_holocene_2001,\n\ttitle = {Holocene climatic change in {Swedish} {Lapland} inferred from an oxygen-isotope record of lacustrine biogenic silica},\n\tvolume = {11},\n\tissn = {0959-6836},\n\turl = {http://journals.sagepub.com/doi/abs/10.1191/095968301678302887},\n\tdoi = {10.1191/095968301678302887},\n\tabstract = {Holocene climatic variability was studied in a 9500-year lake-sediment sequence from the Abisko region in Swedish Lapland, using the oxygen-isotope ratio in diatom biogenic silica (d18Osi). Oxygen-and hydrogen-isotope ratios of waters from the Abisko area suggest that in this region the evaporative flux is small and the isotopic composition of most lakes reflects that of the local precipitation. The hydrological setting of the region and sensitivity analysis of isotopic response to changing climatic parameters such as humidity, inflow and evaporation show that the downcore diatom d18Osi record is primarily controlled by changes in the summer isotopic composition of the lake water. The overall 3.5‰ depletion in d18Osi since the early Holocene is interpreted as an increase in the influence of the Arctic polar continental air mass that carries depleted precipitation. We estimate that this change is associated with a 2.5–4°C cooling that has occurred since the early Holocene. In general, the diatom d18Osi record resembles the average annual air temperature reconstructed for the Greenland ice core GISP2, especially during the past 4000 years, with a pronounced cooling starting at 2000 years BP.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2017-02-07},\n\tjournal = {The Holocene},\n\tauthor = {Shemesh, Aldo and Rosqvist, Gunhild and Rietti-Shati, Miri and Rubensdotter, Lena and Bigler, Christian and Yam, Ruth and Karlén, Wibjörn},\n\tmonth = may,\n\tyear = {2001},\n\tnote = {00095},\n\tkeywords = {\\#nosource, Holocene, Scandinavia, biogenic silica, climatic change, diatoms, lake sediment, oxygen-isotope ratio, stable isotopes},\n\tpages = {447--454},\n}\n\n\n\n\n\n Holocene climatic variability was studied in a 9500-year lake-sediment sequence from the Abisko region in Swedish Lapland, using the oxygen-isotope ratio in diatom biogenic silica (d18Osi). Oxygen-and hydrogen-isotope ratios of waters from the Abisko area suggest that in this region the evaporative flux is small and the isotopic composition of most lakes reflects that of the local precipitation. The hydrological setting of the region and sensitivity analysis of isotopic response to changing climatic parameters such as humidity, inflow and evaporation show that the downcore diatom d18Osi record is primarily controlled by changes in the summer isotopic composition of the lake water. The overall 3.5‰ depletion in d18Osi since the early Holocene is interpreted as an increase in the influence of the Arctic polar continental air mass that carries depleted precipitation. We estimate that this change is associated with a 2.5–4°C cooling that has occurred since the early Holocene. In general, the diatom d18Osi record resembles the average annual air temperature reconstructed for the Greenland ice core GISP2, especially during the past 4000 years, with a pronounced cooling starting at 2000 years BP.\n
\n\n\n\n \n\n \n \n \n \n \n \n Holocene climatic change reconstructed from diatoms, chironomids, pollen and near-infrared spectroscopy at an alpine lake (Sjuodjijaure) in northern Sweden.\n \n \n \n \n\n\n \n Rosén, P.; Segerström, U.; Eriksson, L.; Renberg, I.; and Birks, H. J.\n\n\n \n\n\n\n The Holocene, 11(5): 551–562. July 2001.\n 00139\n\n\n\n
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\n\n\n@article{rosen_holocene_2001,\n\ttitle = {Holocene climatic change reconstructed from diatoms, chironomids, pollen and near-infrared spectroscopy at an alpine lake ({Sjuodjijaure}) in northern {Sweden}},\n\tvolume = {11},\n\tissn = {0959-6836},\n\turl = {http://journals.sagepub.com/doi/abs/10.1191/095968301680223503},\n\tdoi = {10.1191/095968301680223503},\n\tabstract = {The results of a multiproxy study reconstructing the climate history of the last 9300 years in northern Sweden are presented. It is based on diatom, chironomid and pollen analyses, as well as near-infrared spec troscopy (NIRS), of a radiocarbon dated sediment core from Sjuodjijaure (67°22N, 18°04E), situated 100 m above tree-line in the Scandes mountains. Mean July air temperature was reconstructed using transfer functions established for the region. The biological proxies show significant changes in composition during the Holocene and the inferred temperatures all follow the same general trend. For the period between about 9300 to 7300 cal. BP the reconstructions should be interpreted with caution due to the lack of convincing modern analogues in the training set. However the reconstruction suggest that July temperature was on average about the same as today, with several rapid short-term cold and warm periods. Cold periods were dated to about 8500, 8200 and 7600 cal. years BP and a warm period to about 7700 cal. BP. About 7300 cal. BP, a major shift to a warmer climate occurred. Pine migrated into the area, which was previously covered with birch forest. From the mid-Holocene until today the sediment record suggests a descending tree-limit and a gradual lowering of July temperature.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2017-02-07},\n\tjournal = {The Holocene},\n\tauthor = {Rosén, Peter and Segerström, Ulf and Eriksson, Lars and Renberg, Ingemar and Birks, H. J.B.},\n\tmonth = jul,\n\tyear = {2001},\n\tnote = {00139},\n\tkeywords = {\\#nosource, Holocene climate, Lake sediments, Pollen, chironomid, diatom, near-infrared spectroscopy, northern sweden},\n\tpages = {551--562},\n}\n\n\n\n\n\n The results of a multiproxy study reconstructing the climate history of the last 9300 years in northern Sweden are presented. It is based on diatom, chironomid and pollen analyses, as well as near-infrared spec troscopy (NIRS), of a radiocarbon dated sediment core from Sjuodjijaure (67°22N, 18°04E), situated 100 m above tree-line in the Scandes mountains. Mean July air temperature was reconstructed using transfer functions established for the region. The biological proxies show significant changes in composition during the Holocene and the inferred temperatures all follow the same general trend. For the period between about 9300 to 7300 cal. BP the reconstructions should be interpreted with caution due to the lack of convincing modern analogues in the training set. However the reconstruction suggest that July temperature was on average about the same as today, with several rapid short-term cold and warm periods. Cold periods were dated to about 8500, 8200 and 7600 cal. years BP and a warm period to about 7700 cal. BP. About 7300 cal. BP, a major shift to a warmer climate occurred. Pine migrated into the area, which was previously covered with birch forest. From the mid-Holocene until today the sediment record suggests a descending tree-limit and a gradual lowering of July temperature.\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of sequential depositional basins on lake response to urban and agricultural pollution: a palaeoecological analysis of the Qu'Appelle Valley, Saskatchewan, Canada.\n \n \n \n \n\n\n \n Dixit, A. S.; Hall, R. I.; Leavitt&, P. R.; Quinlan, R.; and Smol, J. P.\n\n\n \n\n\n\n Freshwater Biology, 43(3): 319–337. 2001.\n 00033\n\n\n\n
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\n\n\n@article{dixit_effects_2001,\n\ttitle = {Effects of sequential depositional basins on lake response to urban and agricultural pollution: a palaeoecological analysis of the {Qu}'{Appelle} {Valley}, {Saskatchewan}, {Canada}},\n\tvolume = {43},\n\tissn = {1365-2427},\n\tshorttitle = {Effects of sequential depositional basins on lake response to urban and agricultural pollution},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2427.2000.00516.x},\n\tdoi = {10.1046/j.1365-2427.2000.00516.x},\n\tabstract = {1. Palaeolimnological analyses of fossil diatoms and pigments were conducted in four lakes of the Qu'Appelle Valley, Saskatchewan, Canada, to quantify the effect of upstream depositional basins on lake response to urban and agricultural human activities. Pasqua, Echo, Mission and Katepwa lakes exhibit similar modern limnological characteristics, lie sequentially downstream from urban point sources of growth-limiting nitrogen (N), yet drain similarly large areas of farmland (38–40 × 103 km2). 2. Analyses indicated that all lakes were naturally productive, contained eutrophic diatoms (i.e. Stephanodiscus niagarae, S. hantzchii, S. parvus and Aulacoseira granulata), and supported blooms of colonial (as myxoxanthophyll) and potentially toxic N-fixing cyanobacteria (aphanizophyll), even prior to the onset of European settlement (ca. 1890) and urban development (ca. 1930). 3. The onset of agricultural practices ca. 1890 had only modest effects on algal communities in the Qu'Appelle lakes, with subtle increases in eutrophic diatom species (Pasqua, Mission and Katepwa lakes) and 25–50\\% increases in pigment-inferred algal abundance (Echo, Mission and Katepwa lakes). 4. Despite naturally high production, total algal abundance (β-carotene) in upstream Pasqua Lake increased by more than 350\\% after intense urbanization beginning ca. 1930, while eutrophic diatoms became more common and cyanobacteria populations increased ten-fold. Principal components analysis (PCA) explained 64\\% of diatom variance, and identified three eras corresponding to baseline, pre-agricultural communities (1776–1890), an era of high production (ca. 1925–1960) and recent variable community composition following tertiary treatment of urban sewage (ca. 1977–1990). 5. Analyses of three downstream lakes demonstrated that urban impacts following 1930 remained evident in fossil profiles of β-carotene and myxoxanthophyll, but that large blooms of N-fixing cyanobacteria were restricted to the past 25 years at downstream Mission and Katepwa lakes. Similarly, PCA showed that fossil diatom assemblages exhibited little directional variation until the 1970s. 6. Together, these analyses support the hypothesis that upstream lakes were effective at reducing the impacts of point-source urban nutrients on downstream lakes. In contrast, diffuse agricultural activities had only limited impacts on water quality and these were less well ameliorated by upstream basins.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-06-11},\n\tjournal = {Freshwater Biology},\n\tauthor = {Dixit, Aruna S. and Hall, Roland I. and Leavitt\\&, Peter R. and Quinlan, Roberto and Smol, JohN P.},\n\tyear = {2001},\n\tnote = {00033},\n\tkeywords = {\\#nosource, Great Plains, agriculture, diatoms, eutrophication, landscape, palaeolimnology, pigments, prairies, urban},\n\tpages = {319--337},\n}\n\n\n\n\n\n 1. Palaeolimnological analyses of fossil diatoms and pigments were conducted in four lakes of the Qu'Appelle Valley, Saskatchewan, Canada, to quantify the effect of upstream depositional basins on lake response to urban and agricultural human activities. Pasqua, Echo, Mission and Katepwa lakes exhibit similar modern limnological characteristics, lie sequentially downstream from urban point sources of growth-limiting nitrogen (N), yet drain similarly large areas of farmland (38–40 × 103 km2). 2. Analyses indicated that all lakes were naturally productive, contained eutrophic diatoms (i.e. Stephanodiscus niagarae, S. hantzchii, S. parvus and Aulacoseira granulata), and supported blooms of colonial (as myxoxanthophyll) and potentially toxic N-fixing cyanobacteria (aphanizophyll), even prior to the onset of European settlement (ca. 1890) and urban development (ca. 1930). 3. The onset of agricultural practices ca. 1890 had only modest effects on algal communities in the Qu'Appelle lakes, with subtle increases in eutrophic diatom species (Pasqua, Mission and Katepwa lakes) and 25–50% increases in pigment-inferred algal abundance (Echo, Mission and Katepwa lakes). 4. Despite naturally high production, total algal abundance (β-carotene) in upstream Pasqua Lake increased by more than 350% after intense urbanization beginning ca. 1930, while eutrophic diatoms became more common and cyanobacteria populations increased ten-fold. Principal components analysis (PCA) explained 64% of diatom variance, and identified three eras corresponding to baseline, pre-agricultural communities (1776–1890), an era of high production (ca. 1925–1960) and recent variable community composition following tertiary treatment of urban sewage (ca. 1977–1990). 5. Analyses of three downstream lakes demonstrated that urban impacts following 1930 remained evident in fossil profiles of β-carotene and myxoxanthophyll, but that large blooms of N-fixing cyanobacteria were restricted to the past 25 years at downstream Mission and Katepwa lakes. Similarly, PCA showed that fossil diatom assemblages exhibited little directional variation until the 1970s. 6. Together, these analyses support the hypothesis that upstream lakes were effective at reducing the impacts of point-source urban nutrients on downstream lakes. In contrast, diffuse agricultural activities had only limited impacts on water quality and these were less well ameliorated by upstream basins.\n
\n\n\n\n \n\n \n \n \n \n \n \n Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results.\n \n \n \n \n\n\n \n Heiri, O.; Lotter, A. F.; and Lemcke, G.\n\n\n \n\n\n\n Journal of Paleolimnology, 25(1): 101–110. January 2001.\n 02783\n\n\n\n
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\n\n\n@article{heiri_loss_2001,\n\ttitle = {Loss on ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results},\n\tvolume = {25},\n\tissn = {0921-2728, 1573-0417},\n\tshorttitle = {Loss on ignition as a method for estimating organic and carbonate content in sediments},\n\turl = {https://link.springer.com/article/10.1023/A:1008119611481},\n\tdoi = {10.1023/A:1008119611481},\n\tabstract = {Five test runs were performed to assess possible bias when performing the loss on ignition (LOI) method to estimate organic matter and carbonate content of lake sediments. An accurate and stable weight loss was achieved after 2 h of burning pure CaCO3 at 950 °C, whereas LOI of pure graphite at 530 °C showed a direct relation to sample size and exposure time, with only 40-70\\% of the possible weight loss reached after 2 h of exposure and smaller samples losing weight faster than larger ones. Experiments with a standardised lake sediment revealed a strong initial weight loss at 550 °C, but samples continued to lose weight at a slow rate at exposure of up to 64 h, which was likely the effect of loss of volatile salts, structural water of clay minerals or metal oxides, or of inorganic carbon after the initial burning of organic matter. A further test-run revealed that at 550 °C samples in the centre of the furnace lost more weight than marginal samples. At 950 °C this pattern was still apparent but the differences became negligible. Again, LOI was dependent on sample size.An analytical LOI quality control experiment including ten different laboratories was carried out using each laboratory's own LOI procedure as well as a standardised LOI procedure to analyse three different sediments. The range of LOI values between laboratories measured at 550 °C was generally larger when each laboratory used its own method than when using the standard method. This was similar for 950 °C, although the range of values tended to be smaller. The within-laboratory range of LOI measurements for a given sediment was generally small. Comparisons of the results of the individual and the standardised method suggest that there is a laboratory-specific pattern in the results, probably due to differences in laboratory equipment and/or handling that could not be eliminated by standardising the LOI procedure.Factors such as sample size, exposure time, position of samples in the furnace and the laboratory measuring affected LOI results, with LOI at 550 °C being more susceptible to these factors than LOI at 950 °C. We, therefore, recommend analysts to be consistent in the LOI method used in relation to the ignition temperatures, exposure times, and the sample size and to include information on these three parameters when referring to the method.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2018-06-11},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Heiri, Oliver and Lotter, André F. and Lemcke, Gerry},\n\tmonth = jan,\n\tyear = {2001},\n\tnote = {02783},\n\tkeywords = {\\#nosource},\n\tpages = {101--110},\n}\n\n\n\n\n\n Five test runs were performed to assess possible bias when performing the loss on ignition (LOI) method to estimate organic matter and carbonate content of lake sediments. An accurate and stable weight loss was achieved after 2 h of burning pure CaCO3 at 950 °C, whereas LOI of pure graphite at 530 °C showed a direct relation to sample size and exposure time, with only 40-70% of the possible weight loss reached after 2 h of exposure and smaller samples losing weight faster than larger ones. Experiments with a standardised lake sediment revealed a strong initial weight loss at 550 °C, but samples continued to lose weight at a slow rate at exposure of up to 64 h, which was likely the effect of loss of volatile salts, structural water of clay minerals or metal oxides, or of inorganic carbon after the initial burning of organic matter. A further test-run revealed that at 550 °C samples in the centre of the furnace lost more weight than marginal samples. At 950 °C this pattern was still apparent but the differences became negligible. Again, LOI was dependent on sample size.An analytical LOI quality control experiment including ten different laboratories was carried out using each laboratory's own LOI procedure as well as a standardised LOI procedure to analyse three different sediments. The range of LOI values between laboratories measured at 550 °C was generally larger when each laboratory used its own method than when using the standard method. This was similar for 950 °C, although the range of values tended to be smaller. The within-laboratory range of LOI measurements for a given sediment was generally small. Comparisons of the results of the individual and the standardised method suggest that there is a laboratory-specific pattern in the results, probably due to differences in laboratory equipment and/or handling that could not be eliminated by standardising the LOI procedure.Factors such as sample size, exposure time, position of samples in the furnace and the laboratory measuring affected LOI results, with LOI at 550 °C being more susceptible to these factors than LOI at 950 °C. We, therefore, recommend analysts to be consistent in the LOI method used in relation to the ignition temperatures, exposure times, and the sample size and to include information on these three parameters when referring to the method.\n
\n\n\n\n \n\n \n \n \n \n \n \n Diatoms as indicators of Holocene climate and environmental change in northern Sweden.\n \n \n \n \n\n\n \n Bigler, C.\n\n\n \n\n\n\n Ph.D. Thesis, Umeå University, Umeå, Sweden, 2001.\n \n\n\n\n
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\n\n\n@phdthesis{bigler_diatoms_2001,\n\taddress = {Umeå, Sweden},\n\ttype = {Doctoral {Thesis}},\n\ttitle = {Diatoms as indicators of {Holocene} climate and environmental change in northern {Sweden}},\n\turl = {http://www.diva-portal.org/smash/record.jsf?pid=diva2:141073},\n\tabstract = {The objective of the thesis was to explore the potential of diatoms (Bacillariophyceae) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49' ...},\n\tlanguage = {eng},\n\turldate = {2017-02-07},\n\tschool = {Umeå University},\n\tauthor = {Bigler, Christian},\n\tcollaborator = {Renberg, Ingemar and Hall, Roland I.},\n\tyear = {2001},\n\tkeywords = {\\#nosource},\n}\n\n\n\n\n\n The objective of the thesis was to explore the potential of diatoms (Bacillariophyceae) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49' ...\n
\n\n\n\n \n\n \n \n \n \n \n \n Modelling Dissolved Organic Carbon Turnover in Humic Lake Örträsket, Sweden.\n \n \n \n \n\n\n \n Pers, C.; Rahm, L.; Jonsson, A.; Bergström, A.; and Jansson, M.\n\n\n \n\n\n\n Environmental Modeling & Assessment, 6(3): 159–172. September 2001.\n \n\n\n\n
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\n\n\n@article{pers_modelling_2001,\n\ttitle = {Modelling {Dissolved} {Organic} {Carbon} {Turnover} in {Humic} {Lake} Örträsket, {Sweden}},\n\tvolume = {6},\n\tissn = {1420-2026, 1573-2967},\n\turl = {http://link.springer.com/article/10.1023/A:1011953730983},\n\tdoi = {10.1023/A:1011953730983},\n\tabstract = {The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993–1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel. The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5−2.5 mg C l−1 yr−1, where photooxidation is responsible for approximately 10\\%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-07},\n\tjournal = {Environmental Modeling \\& Assessment},\n\tauthor = {Pers, Charlotta and Rahm, Lars and Jonsson, Anders and Bergström, Ann-Kristin and Jansson, Mats},\n\tmonth = sep,\n\tyear = {2001},\n\tkeywords = {\\#nosource, DOC model, fluid particle model, lake, organic matter},\n\tpages = {159--172},\n}\n\n\n\n\n\n The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993–1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel. The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5−2.5 mg C l−1 yr−1, where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.\n
\n\n\n\n \n\n \n \n \n \n \n \n Bacterioplankton Production in Lakes along an Altitude Gradient in the Subarctic North of Sweden.\n \n \n \n \n\n\n \n Karlsson, J.; Jonsson, A.; and Jansson, M.\n\n\n \n\n\n\n Microbial Ecology, 42(3): 372–382. October 2001.\n \n\n\n\n
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\n\n\n@article{karlsson_bacterioplankton_2001,\n\ttitle = {Bacterioplankton {Production} in {Lakes} along an {Altitude} {Gradient} in the {Subarctic} {North} of {Sweden}},\n\tvolume = {42},\n\tissn = {0095-3628, 1432-184X},\n\turl = {http://link.springer.com/article/10.1007/s00248-001-0009-9},\n\tdoi = {10.1007/s00248-001-0009-9},\n\tabstract = {We examined changes in bacterioplankton standing stock and production in subarctic lakes in the north of Sweden to elucidate their coupling to lake physical, chemical, and biological characteristics. Sixteen lakes situated along an altitude gradient extending from the coniferous forest to the high-alpine belt were studied during 1998 and 1999. The summer mean bacterial numbers and production varied substantially between the lakes, with a general trend toward decreasing values with increasing altitude. The results demonstrate that P probably restricted bacterial utilization of DOC in the coniferous forest lakes, while low DOC concentrations limited bacterial growth during the summer in the alpine lakes. The primary production of plankton was insufficient to support bacterial production in the lakes. High input of allochthonous DOC to the alpine lakes in spring was sufficient both to increase the bacterial production and to induce P-limitation. As a consequence, there was a tendency toward higher bacterial activity in the spring compared to the summer in the alpine lakes. The results indicate that most of the bacterial standing stock and production are supported by allochthonous DOC plus DOC from benthic production, and more or less limited by the phosphorus supply. We therefore suggest that bacteria populations in subarctic lakes may be indirectly affected by climate variations through its impact on the input of DOC and nutrients from the lake catchments.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2017-02-06},\n\tjournal = {Microbial Ecology},\n\tauthor = {Karlsson, J. and Jonsson, A. and Jansson, M.},\n\tmonth = oct,\n\tyear = {2001},\n\tkeywords = {\\#nosource, Altitude gradient, DOC, bacterioplankton production, lake ecosystem, subarctic},\n\tpages = {372--382},\n}\n\n\n\n\n\n We examined changes in bacterioplankton standing stock and production in subarctic lakes in the north of Sweden to elucidate their coupling to lake physical, chemical, and biological characteristics. Sixteen lakes situated along an altitude gradient extending from the coniferous forest to the high-alpine belt were studied during 1998 and 1999. The summer mean bacterial numbers and production varied substantially between the lakes, with a general trend toward decreasing values with increasing altitude. The results demonstrate that P probably restricted bacterial utilization of DOC in the coniferous forest lakes, while low DOC concentrations limited bacterial growth during the summer in the alpine lakes. The primary production of plankton was insufficient to support bacterial production in the lakes. High input of allochthonous DOC to the alpine lakes in spring was sufficient both to increase the bacterial production and to induce P-limitation. As a consequence, there was a tendency toward higher bacterial activity in the spring compared to the summer in the alpine lakes. The results indicate that most of the bacterial standing stock and production are supported by allochthonous DOC plus DOC from benthic production, and more or less limited by the phosphorus supply. We therefore suggest that bacteria populations in subarctic lakes may be indirectly affected by climate variations through its impact on the input of DOC and nutrients from the lake catchments.\n
\n\n\n\n \n\n \n \n \n \n \n \n Stoichiometry and Population Growth in Osmotrophs and Non-Osmotrophs.\n \n \n \n \n\n\n \n Cherif, M.\n\n\n \n\n\n\n In eLS. John Wiley & Sons, Ltd, 2001.\n \n\n\n\n
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\n\n\n@incollection{cherif_stoichiometry_2001,\n\ttitle = {Stoichiometry and {Population} {Growth} in {Osmotrophs} and {Non}-{Osmotrophs}},\n\tcopyright = {Copyright © 2001 John Wiley \\& Sons, Ltd. All rights reserved.},\n\tisbn = {978-0-470-01590-2},\n\turl = {http://onlinelibrary.wiley.com.proxy.ub.umu.se/doi/10.1002/9780470015902.a0026353/abstract},\n\tabstract = {Growth is a process fundamental to life. It implies an increase in not only energy and information but also matter content. Recent advances in ecology have demonstrated that the elemental composition of organisms – their stoichiometry – is inextricably linked to their growth rate. Unbalances between the demands of elements for growth and their relative availabilities often result in elemental limitation. Also, different cellular components have different elemental compositions, and thus changes in allocation between uptake and assembly machineries affect both growth rate and elemental composition at the organismal level. Osmotrophs (including autotrophs) acquire essential elements through a vast set of separate molecules, resulting in more flexible stoichiometries compared to non-osmotrophs that ingest their preys in one package. Relationships between elemental composition and growth rate should be considered differently for individuals and for populations, as processes and mechanisms differ between the two scales, and more generally among the various biological scales.\n\nKey Concepts\nKey Concepts\n\n\n\n* Growth for organisms is by nature a stoichiometric process that involves multiple currencies: energy, information and matter, itself made of multiple essential elements.\n\n* Most organisms are stoichiometrically homeostatic, that is, they need to keep the ratios of elements in their protoplasm within narrow limits. However, some organisms use storage structures, such as vacuoles, to further modulate their stoichiometry.\n\n* According to Liebig's law of the minimum, growth is mostly limited by the element that is in least supply compared to the demand of the growing organism.\n\n* Organisms can resort to a set of behavioural and physiological strategies when facing elemental limitation.\n\n* Osmotrophs (including autotrophs), which can regulate the stoichiometry of their diet at the uptake level, differ from non-osmotrophs (including some large protists and all metazoans), which ingest all the essential elements at once.\n\n* Another strategy is to adapt the relative investment into cellular machineries that differ in their elemental composition, but this comes with important repercussions on cellular functions.\n\n* Excretion of the elements in excess is another strategy, but there are associated costs, too, leading to only a narrow range of diet elemental composition that optimises growth.\n\n* A priori, elemental limitation at the level of populations should differ from limitation of individual growth because of demographic processes.\n\n* Even if differences between the two biological levels are ignored, including stoichiometry into classical population models yields interesting novel predictions, confirming the importance of stoichiometry to understand the growth process.},\n\tlanguage = {en},\n\turldate = {2017-05-27},\n\tbooktitle = {{eLS}},\n\tpublisher = {John Wiley \\& Sons, Ltd},\n\tauthor = {Cherif, Mehdi},\n\tyear = {2001},\n\tdoi = {10.1002/9780470015902.a0026353},\n\tkeywords = {\\#nosource, autotrophs, compensatory feeding, droop model, elemental limitation, excretion, homeostasis, metazoans, osmotrophs, phosphorus, ribosomes, uptake},\n}\n\n\n\n\n\n Growth is a process fundamental to life. It implies an increase in not only energy and information but also matter content. Recent advances in ecology have demonstrated that the elemental composition of organisms – their stoichiometry – is inextricably linked to their growth rate. Unbalances between the demands of elements for growth and their relative availabilities often result in elemental limitation. Also, different cellular components have different elemental compositions, and thus changes in allocation between uptake and assembly machineries affect both growth rate and elemental composition at the organismal level. Osmotrophs (including autotrophs) acquire essential elements through a vast set of separate molecules, resulting in more flexible stoichiometries compared to non-osmotrophs that ingest their preys in one package. Relationships between elemental composition and growth rate should be considered differently for individuals and for populations, as processes and mechanisms differ between the two scales, and more generally among the various biological scales. Key Concepts Key Concepts * Growth for organisms is by nature a stoichiometric process that involves multiple currencies: energy, information and matter, itself made of multiple essential elements. * Most organisms are stoichiometrically homeostatic, that is, they need to keep the ratios of elements in their protoplasm within narrow limits. However, some organisms use storage structures, such as vacuoles, to further modulate their stoichiometry. * According to Liebig's law of the minimum, growth is mostly limited by the element that is in least supply compared to the demand of the growing organism. * Organisms can resort to a set of behavioural and physiological strategies when facing elemental limitation. * Osmotrophs (including autotrophs), which can regulate the stoichiometry of their diet at the uptake level, differ from non-osmotrophs (including some large protists and all metazoans), which ingest all the essential elements at once. * Another strategy is to adapt the relative investment into cellular machineries that differ in their elemental composition, but this comes with important repercussions on cellular functions. * Excretion of the elements in excess is another strategy, but there are associated costs, too, leading to only a narrow range of diet elemental composition that optimises growth. * A priori, elemental limitation at the level of populations should differ from limitation of individual growth because of demographic processes. * Even if differences between the two biological levels are ignored, including stoichiometry into classical population models yields interesting novel predictions, confirming the importance of stoichiometry to understand the growth process.\n
\n\n\n\n \n\n \n \n \n \n \n \n Chironomids as indicators of climate change: a 100‐lake training set from a subarctic region of northern Sweden (Lapland).\n \n \n \n \n\n\n \n Larocque, I.; Hall, R. I.; and Grahn, E.\n\n\n \n\n\n\n Journal of Paleolimnology, 26(3): 307–322. September 2001.\n \n\n\n\n
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\n\n\n@article{larocque_chironomids_2001,\n\ttitle = {Chironomids as indicators of climate change: a 100‐lake training set from a subarctic region of northern {Sweden} ({Lapland})},\n\tvolume = {26},\n\tissn = {0921-2728, 1573-0417},\n\tshorttitle = {Chironomids as indicators of climate change},\n\turl = {http://link.springer.com.proxy.ub.umu.se/article/10.1023/A%3A1017524101783},\n\tdoi = {10.1023/A:1017524101783},\n\tabstract = {00214},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2015-10-04},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Larocque, I. and Hall, R. I. and Grahn, E.},\n\tmonth = sep,\n\tyear = {2001},\n\tkeywords = {\\#nosource, Geochemistry, Hydrobiology, Hydrogeology, Lapland, Meteorology/Climatology, Ordination, Sedimentology, Sweden, abisko, canonical correspondence analysis, chironomids, climate change, temperature, transfer function},\n\tpages = {307--322},\n}\n\n\n\n\n\n 00214\n
\n\n\n\n \n\n \n \n \n \n \n \n How many chironomid head capsules are enough? A statistical approach to determine sample size for palaeoclimatic reconstructions.\n \n \n \n \n\n\n \n Larocque, I.\n\n\n \n\n\n\n Palaeogeography, Palaeoclimatology, Palaeoecology, 172(1–2): 133–142. August 2001.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{larocque_how_2001,\n\ttitle = {How many chironomid head capsules are enough? {A} statistical approach to determine sample size for palaeoclimatic reconstructions},\n\tvolume = {172},\n\tissn = {0031-0182},\n\tshorttitle = {How many chironomid head capsules are enough?},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0031018201002784},\n\tdoi = {10.1016/S0031-0182(01)00278-4},\n\tabstract = {Chironomid-inferred temperature reconstruction has been shown to be accurate but the method is tenuous and time consuming. With the increased importance of high-resolution studies, more samples should be analysed, increasing the time taken to obtain climate reconstructions. Here, the number of head capsules that should be used to be both time effective and statistically representative for climate reconstruction was tested. In 30 of the 33 samples, counting 50 head capsules was enough to obtain a temperature reconstruction similar to the one obtained by counting 150 or more head capsules. Counting 90 head capsules or more gave the lowest differences between temperature estimates with 200 head capsules. There was a significant increase in the number of new taxa found in relation with the number of head capsules counted. For ecological purposes, the more head capsules that are identified, the better is the representation of the population.},\n\tnumber = {1–2},\n\turldate = {2015-10-04},\n\tjournal = {Palaeogeography, Palaeoclimatology, Palaeoecology},\n\tauthor = {Larocque, Isabelle},\n\tmonth = aug,\n\tyear = {2001},\n\tkeywords = {\\#nosource, Chironomid-inferred temperature, Representativity, Sample size},\n\tpages = {133--142},\n}\n\n\n\n\n\n Chironomid-inferred temperature reconstruction has been shown to be accurate but the method is tenuous and time consuming. With the increased importance of high-resolution studies, more samples should be analysed, increasing the time taken to obtain climate reconstructions. Here, the number of head capsules that should be used to be both time effective and statistically representative for climate reconstruction was tested. In 30 of the 33 samples, counting 50 head capsules was enough to obtain a temperature reconstruction similar to the one obtained by counting 150 or more head capsules. Counting 90 head capsules or more gave the lowest differences between temperature estimates with 200 head capsules. There was a significant increase in the number of new taxa found in relation with the number of head capsules counted. For ecological purposes, the more head capsules that are identified, the better is the representation of the population.\n
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\n\n \n \n 2000\n \n \n (8)\n \n \n
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\n \n \n\n \n \n \n \n \n \n Diatom transfer-functions for quantifying past air temperature, pH and total organic carbon concentration from lakes in northern Sweden.\n \n \n \n \n\n\n \n Rosén, P.; Hall, R.; Korsman, T.; and Renberg, I.\n\n\n \n\n\n\n Journal of Paleolimnology, 24(2): 109–123. August 2000.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{rosen_diatom_2000,\n\ttitle = {Diatom transfer-functions for quantifying past air temperature, {pH} and total organic carbon concentration from lakes in northern {Sweden}},\n\tvolume = {24},\n\tissn = {1573-0417},\n\turl = {https://doi.org/10.1023/A:1008128014721},\n\tdoi = {10.1023/A:1008128014721},\n\tabstract = {The relationships between diatoms (Bacillariophyceae) in surface sediments of lakes and summer air temperature, pH and total organic carbon concentration (TOC) were explored along a steep climatic gradient in northern Sweden to provide a tool to infer past climate conditions from sediment cores. The study sites are in an area with low human impact and range from boreal forest to alpine tundra. Canonical correspondence analysis (CCA) constrained to mean July air temperature and pH clearly showed that diatom community composition was different between lakes situated in conifer-, mountain birch- and alpine-vegetation zones. As a consequence, diatoms and multivariate ordination methods can be used to infer past changes in treeline position and dominant forest type. Quantitative inference models were developed to estimate mean July air temperature, pH and TOC from sedimentary diatom assemblages using weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regression. Relationships between diatoms and mean July air temperature were independent of lake-water pH, TOC, alkalinity and maximum depth. The results demonstrated that diatoms in lake sediments can provide useful and independent quantitative information for estimating past changes in mean July air temperature (R2jack = 0.62, RMSEP = 0.86 °C; R2 and root mean squared error of prediction (RMSEP) based on jack-knifing), pH (R2jack = 0.61, RMSEP = 0.30) and TOC (R2jack = 0.49, RMSEP = 1.33 mg l-1). The paper focuses mainly on the relationship between diatom community composition and mean July air temperature, but the relationships to pH and TOC are also discussed.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2023-07-21},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Rosén, Peter and Hall, Roland and Korsman, Tom and Renberg, Ingemar},\n\tmonth = aug,\n\tyear = {2000},\n\tkeywords = {\\#nosource, climate change, diatoms, lake sediments, pH, temperature, transfer functions},\n\tpages = {109--123},\n}\n\n\n\n\n\n The relationships between diatoms (Bacillariophyceae) in surface sediments of lakes and summer air temperature, pH and total organic carbon concentration (TOC) were explored along a steep climatic gradient in northern Sweden to provide a tool to infer past climate conditions from sediment cores. The study sites are in an area with low human impact and range from boreal forest to alpine tundra. Canonical correspondence analysis (CCA) constrained to mean July air temperature and pH clearly showed that diatom community composition was different between lakes situated in conifer-, mountain birch- and alpine-vegetation zones. As a consequence, diatoms and multivariate ordination methods can be used to infer past changes in treeline position and dominant forest type. Quantitative inference models were developed to estimate mean July air temperature, pH and TOC from sedimentary diatom assemblages using weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regression. Relationships between diatoms and mean July air temperature were independent of lake-water pH, TOC, alkalinity and maximum depth. The results demonstrated that diatoms in lake sediments can provide useful and independent quantitative information for estimating past changes in mean July air temperature (R2jack = 0.62, RMSEP = 0.86 °C; R2 and root mean squared error of prediction (RMSEP) based on jack-knifing), pH (R2jack = 0.61, RMSEP = 0.30) and TOC (R2jack = 0.49, RMSEP = 1.33 mg l-1). The paper focuses mainly on the relationship between diatom community composition and mean July air temperature, but the relationships to pH and TOC are also discussed.\n
\n\n\n\n \n\n \n \n \n \n \n \n A diatom-training set for palaeoclimatic inferences from lakes in northern Sweden.\n \n \n \n \n\n\n \n Bigler, C.; Hall, R. I.; and Renberg, I.\n\n\n \n\n\n\n SIL Proceedings, 1922-2010, 27(3): 1174–1182. November 2000.\n Publisher: Taylor & Francis _eprint: https://doi.org/10.1080/03680770.1998.11901421\n\n\n\n
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\n\n\n\n@article{bigler_diatom-training_2000,\n\ttitle = {A diatom-training set for palaeoclimatic inferences from lakes in northern {Sweden}},\n\tvolume = {27},\n\tissn = {0368-0770},\n\turl = {https://doi.org/10.1080/03680770.1998.11901421},\n\tdoi = {10.1080/03680770.1998.11901421},\n\tnumber = {3},\n\turldate = {2020-03-19},\n\tjournal = {SIL Proceedings, 1922-2010},\n\tauthor = {Bigler, Christian and Hall, Roland I. and Renberg, Ingemar},\n\tmonth = nov,\n\tyear = {2000},\n\tnote = {Publisher: Taylor \\& Francis\n\\_eprint: https://doi.org/10.1080/03680770.1998.11901421},\n\tkeywords = {\\#nosource},\n\tpages = {1174--1182},\n}\n\n\n\n\n\n \n\n \n \n \n \n \n \n Do diatoms in the Swiss Alps reflect the length of ice-cover?.\n \n \n \n \n\n\n \n Lotter, A. F.; and Bigler, C.\n\n\n \n\n\n\n Aquatic Sciences, 62(2): 125–141. August 2000.\n 00214\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{lotter_diatoms_2000,\n\ttitle = {Do diatoms in the {Swiss} {Alps} reflect the length of ice-cover?},\n\tvolume = {62},\n\tissn = {1015-1621, 1420-9055},\n\turl = {http://link.springer.com/article/10.1007/s000270050002},\n\tdoi = {10.1007/s000270050002},\n\tabstract = {Diatom analyses in the water column, sediment traps, surficial sediments as well as in a short sediment core from Hagelseewli (2339 m asl, Swiss Alps) give information about the present-day seasonal cycle of diatom blooms, taphonomic processes in the lake basin and the lake's history. Analyses of surficial sediments show that water depth and thus light and nutrient availability is the most important factor influencing the production and distribution of diatom assemblages in Hagelseewli, and that periphytic diatom valves deposited in the deeper part of the basin originate from the shallow, littoral parts and are transported to the central part by processes such as lateral currents or sediment focussing. The lake is characterised by a very short period (2-3 months) of open water. Water-column and sediment-trap data revealed that planktonic diatoms bloom during and after the ice break-up, whereas mainly periphytic Fragilaria species entered the traps during the ice-covered period. These results suggest that plankton development is strongly inhibited by the ice-cover, with longer periods of ice-cover favouring Fragilaria species in Hagelseewli. The diatom analysis of a short sediment core that includes the last five centuries revealed several changes in the proportion of planktonic diatoms to Fragilaria species. The colder phases of the Little Ice-Age correspond to phases of lower concentration of planktonic diatoms. The highest, statistically significant amount of variance in the downcore diatom data is explained by winter precipitation, which directly influences the length of the ice-cover but inversely influences the light regime.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-07},\n\tjournal = {Aquatic Sciences},\n\tauthor = {Lotter, André F. and Bigler, Christian},\n\tmonth = aug,\n\tyear = {2000},\n\tnote = {00214},\n\tkeywords = {\\#nosource, Climate change, diatoms, ice-cover, sediment traps, surface sediments},\n\tpages = {125--141},\n}\n\n\n\n\n\n Diatom analyses in the water column, sediment traps, surficial sediments as well as in a short sediment core from Hagelseewli (2339 m asl, Swiss Alps) give information about the present-day seasonal cycle of diatom blooms, taphonomic processes in the lake basin and the lake's history. Analyses of surficial sediments show that water depth and thus light and nutrient availability is the most important factor influencing the production and distribution of diatom assemblages in Hagelseewli, and that periphytic diatom valves deposited in the deeper part of the basin originate from the shallow, littoral parts and are transported to the central part by processes such as lateral currents or sediment focussing. The lake is characterised by a very short period (2-3 months) of open water. Water-column and sediment-trap data revealed that planktonic diatoms bloom during and after the ice break-up, whereas mainly periphytic Fragilaria species entered the traps during the ice-covered period. These results suggest that plankton development is strongly inhibited by the ice-cover, with longer periods of ice-cover favouring Fragilaria species in Hagelseewli. The diatom analysis of a short sediment core that includes the last five centuries revealed several changes in the proportion of planktonic diatoms to Fragilaria species. The colder phases of the Little Ice-Age correspond to phases of lower concentration of planktonic diatoms. The highest, statistically significant amount of variance in the downcore diatom data is explained by winter precipitation, which directly influences the length of the ice-cover but inversely influences the light regime.\n
\n\n\n\n \n\n \n \n \n \n \n \n Causes and effects of long periods of ice cover on a remote high Alpine lake.\n \n \n \n \n\n\n \n Ohlendorf, C.; Bigler, C.; Goudsmit, G.; Lemcke, G.; Livingstone, D. M.; Lotter, A. F.; Müller, B.; and Sturm, M.\n\n\n \n\n\n\n Journal of Limnology, 59(1s): 65–80. September 2000.\n 00052\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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\n\n\n@article{ohlendorf_causes_2000,\n\ttitle = {Causes and effects of long periods of ice cover on a remote high {Alpine} lake},\n\tvolume = {59},\n\tcopyright = {Copyright (c) 2000 Christian OHLENDORF, Christian BIGLER, Gerrit-Hein GOUDSMIT, Gerry LEMCKE, David M. LIVINGSTONE, André F. LOTTER, Beat MÜLLER, Michael STURM},\n\tissn = {1723-8633},\n\turl = {http://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2000.s1.65},\n\tdoi = {10.4081/jlimnol.2000.s1.65},\n\tabstract = {The response of the physical and chemical limnology of Hagelseewli (2339 m a.s.l.) to local meteorological forcing was investigated from 1996 to 1998 using an automatic weather station, thermistor chains, water samples and sediment traps. On-site meteorological measurements revealed the paramount importance of local topographic shading for the limnology of the lake. A high cliff to the south diminishes incident radiation by 15\\% to 90\\%, resulting in a long period of ice cover. Hence, the spring and summer seasons are extremely condensed, allowing only about 2 months per year for mixing, oxygen uptake, nutrient inflow, water exchange and phytoplankton growth. Regular measurements of water temperature, chemistry and diatom composition show that Hagelseewli responds very rapidly to changes in nutrient concentrations and light conditions. This response is restricted mainly to an extremely short productivity pulse, which takes place as soon as the lake is completely free of ice. Ice-free conditions are indicated by the occurrence of planktonic diatoms. In contrast to most low-altitude lakes, maximum productivity occurs in the middle of the water column (6-9 m), where first light, and then soluble reactive phosphorus (SRP), are the limiting factors. During the period of thawing, large amounts of ammonium enter the lake. Nevertheless, allochthonous nutrient input is not important because SRP, the limiting nutrient for algal growth, originates from the sediments. Water chemistry data and data from sediment traps show that, although autochthonous calcite precipitation does occur, the calcite crystals are redissolved completely in the bottom waters during the extended period of ice cover. Thus, the most important factor for changes in the nutrient budget, primary production and preservation of calcite is the bottom water oxygen status, which is governed by the occurrence of an ice-free period. We hypothesise that the duration of the ice-free period is of minor importance for the generation of particles that might be archived in the sedimentary rec??ord as proxy climate indicators. Such particles are produced mainly during times of peak primary production, which last only for a few days before production decreases again to very low levels. Therefore, with respect to the type of climatic signal that might be recorded in Hagelseewli, we presume that what is most likely to be archived in the sedimentary record is the mere occurrence, rather than the duration of the ice-free period.},\n\tlanguage = {en},\n\tnumber = {1s},\n\turldate = {2017-02-07},\n\tjournal = {Journal of Limnology},\n\tauthor = {Ohlendorf, Christian and Bigler, Christian and Goudsmit, Gerrit-Hein and Lemcke, Gerry and Livingstone, David M. and Lotter, André F. and Müller, Beat and Sturm, Michael},\n\tmonth = sep,\n\tyear = {2000},\n\tnote = {00052},\n\tkeywords = {\\#nosource, diatoms, high Alpine lakes, ice cover, meteorological data, sediment traps, water chemistry},\n\tpages = {65--80},\n}\n\n\n\n\n\n The response of the physical and chemical limnology of Hagelseewli (2339 m a.s.l.) to local meteorological forcing was investigated from 1996 to 1998 using an automatic weather station, thermistor chains, water samples and sediment traps. On-site meteorological measurements revealed the paramount importance of local topographic shading for the limnology of the lake. A high cliff to the south diminishes incident radiation by 15% to 90%, resulting in a long period of ice cover. Hence, the spring and summer seasons are extremely condensed, allowing only about 2 months per year for mixing, oxygen uptake, nutrient inflow, water exchange and phytoplankton growth. Regular measurements of water temperature, chemistry and diatom composition show that Hagelseewli responds very rapidly to changes in nutrient concentrations and light conditions. This response is restricted mainly to an extremely short productivity pulse, which takes place as soon as the lake is completely free of ice. Ice-free conditions are indicated by the occurrence of planktonic diatoms. In contrast to most low-altitude lakes, maximum productivity occurs in the middle of the water column (6-9 m), where first light, and then soluble reactive phosphorus (SRP), are the limiting factors. During the period of thawing, large amounts of ammonium enter the lake. Nevertheless, allochthonous nutrient input is not important because SRP, the limiting nutrient for algal growth, originates from the sediments. Water chemistry data and data from sediment traps show that, although autochthonous calcite precipitation does occur, the calcite crystals are redissolved completely in the bottom waters during the extended period of ice cover. Thus, the most important factor for changes in the nutrient budget, primary production and preservation of calcite is the bottom water oxygen status, which is governed by the occurrence of an ice-free period. We hypothesise that the duration of the ice-free period is of minor importance for the generation of particles that might be archived in the sedimentary rec??ord as proxy climate indicators. Such particles are produced mainly during times of peak primary production, which last only for a few days before production decreases again to very low levels. Therefore, with respect to the type of climatic signal that might be recorded in Hagelseewli, we presume that what is most likely to be archived in the sedimentary record is the mere occurrence, rather than the duration of the ice-free period.\n
\n\n\n\n \n\n \n \n \n \n \n \n Near-infrared spectrometry (NIRS): a new tool for inferring past climatic changes from lake sediments.\n \n \n \n \n\n\n \n Rosén, P.; Dåbakk, E.; Renberg, I.; Nilsson, M.; and Hall, R.\n\n\n \n\n\n\n The Holocene, 10(2): 161–166. February 2000.\n \n\n\n\n
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\n\n\n@article{rosen_near-infrared_2000,\n\ttitle = {Near-infrared spectrometry ({NIRS}): a new tool for inferring past climatic changes from lake sediments},\n\tvolume = {10},\n\tissn = {0959-6836, 1477-0911},\n\tshorttitle = {Near-infrared spectrometry ({NIRS})},\n\turl = {http://hol.sagepub.com.proxy.ub.umu.se/content/10/2/161},\n\tdoi = {10.1191/095968300670554274},\n\tabstract = {This study tests the hypothesis that lake sediments containclimate–related information that can be detected by near–infrared spectrometry (NIRS), and that NIRS can be used to infer past climatic changes from analysis of sediment cores. NIRS is a rapid and non–destructive technique that measures attributes of the chemical composition of organic materials. A training set of 76 lakes from northern Sweden, spanning a broad altitudinal gradient, was used to assess whether lake altitude and vegetation zones can be modelled from NIR spectra of surface sediments (0–1 cm) using partial least squares (PLS) regression and soft independent modelling of class analogies (SIMCA) classification. Lake altitude served as a surrogate variable reflecting differences in climatic conditions among sites. After spectral filtering using orthogonal signal correction (OSC), cross-validated predictions explained 86\\% of the variance in altitude and the prediction error (root mean square error) was 78 m, corresponding to 8.3\\%o of the gradient (390–1250 m above sea level). To evaluate the significance of NIR spectral differences between surface sediments of lakes in different vegetation zones (mountain–birch forest, dwarf shrub and alpine heath), principal component analysis (PCA) models were developed separately for lakes in each vegetation zone. Multivariate classification analysis demonstrated that NIR spectra of surficial sediments differed between lakes located in different vegetation zones. A separate sediment data set from 56 lakes was used to assess sediment ageing effects on NIR signals. Marked similarities between NIR spectra in surface sediments (0–1 cm) and sediments from 1–2 cm depth indicated that degradation of organic material following sediment consolidation resulted in little loss or change of climate–related information. Finally, to assess the ability of NIRS methods to reconstruct past climatic changes over Holocene timescales, we applied the NIRS–altitude model to sediments in a core from a small mountain lake. Estimates of mean July air temperature based on the NIRS–altitude transfer function showed similar trends compared with inferences from chironomids, diatoms and pollen from the same core. Overall, the results indicate that changes in NIR spectra from lake sediments reflect differences in climate, and that NIRS models based on surface–sediment samples can be applied to sediment cores for retrospective analysis.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2015-10-04},\n\tjournal = {The Holocene},\n\tauthor = {Rosén, Peter and Dåbakk, Eigil and Renberg, Ingemar and Nilsson, Mats and Hall, Roland},\n\tmonth = feb,\n\tyear = {2000},\n\tkeywords = {\\#nosource, Holocene, Lake sediments, NIRS, Near–infrared spectrometry, Sweden, climatic change, july temperature, northern, transfer function},\n\tpages = {161--166},\n}\n\n\n\n\n\n This study tests the hypothesis that lake sediments containclimate–related information that can be detected by near–infrared spectrometry (NIRS), and that NIRS can be used to infer past climatic changes from analysis of sediment cores. NIRS is a rapid and non–destructive technique that measures attributes of the chemical composition of organic materials. A training set of 76 lakes from northern Sweden, spanning a broad altitudinal gradient, was used to assess whether lake altitude and vegetation zones can be modelled from NIR spectra of surface sediments (0–1 cm) using partial least squares (PLS) regression and soft independent modelling of class analogies (SIMCA) classification. Lake altitude served as a surrogate variable reflecting differences in climatic conditions among sites. After spectral filtering using orthogonal signal correction (OSC), cross-validated predictions explained 86% of the variance in altitude and the prediction error (root mean square error) was 78 m, corresponding to 8.3%o of the gradient (390–1250 m above sea level). To evaluate the significance of NIR spectral differences between surface sediments of lakes in different vegetation zones (mountain–birch forest, dwarf shrub and alpine heath), principal component analysis (PCA) models were developed separately for lakes in each vegetation zone. Multivariate classification analysis demonstrated that NIR spectra of surficial sediments differed between lakes located in different vegetation zones. A separate sediment data set from 56 lakes was used to assess sediment ageing effects on NIR signals. Marked similarities between NIR spectra in surface sediments (0–1 cm) and sediments from 1–2 cm depth indicated that degradation of organic material following sediment consolidation resulted in little loss or change of climate–related information. Finally, to assess the ability of NIRS methods to reconstruct past climatic changes over Holocene timescales, we applied the NIRS–altitude model to sediments in a core from a small mountain lake. Estimates of mean July air temperature based on the NIRS–altitude transfer function showed similar trends compared with inferences from chironomids, diatoms and pollen from the same core. Overall, the results indicate that changes in NIR spectra from lake sediments reflect differences in climate, and that NIRS models based on surface–sediment samples can be applied to sediment cores for retrospective analysis.\n
\n\n\n\n \n\n \n \n \n \n \n \n Modelling the Effects of Patch Size on Vegetation Dynamics: Bracken [Pteridium aquilinum (L.) Kuhn] under Grazing.\n \n \n \n \n\n\n \n Birch, C. P. D.; Vuichard, N.; and Werkman, B. R.\n\n\n \n\n\n\n Annals of Botany, 85(2): 63–76. April 2000.\n 00023\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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\n\n\n@article{birch_modelling_2000,\n\ttitle = {Modelling the {Effects} of {Patch} {Size} on {Vegetation} {Dynamics}: {Bracken} [{Pteridium} aquilinum ({L}.) {Kuhn}] under {Grazing}},\n\tvolume = {85},\n\tissn = {0305-7364},\n\tshorttitle = {Modelling the {Effects} of {Patch} {Size} on {Vegetation} {Dynamics}},\n\turl = {https://academic.oup.com/aob/article/85/suppl_2/63/194608},\n\tdoi = {10.1093/oxfordjournals.aob.a010319},\n\tabstract = {Abstract. A new spatial simulation model of vegetation dynamics, called ‘VegeTate’, was applied to relationships between expansion of bracken (Pteridium aquili},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2018-06-11},\n\tjournal = {Annals of Botany},\n\tauthor = {Birch, Colin P. D. and Vuichard, Nicolas and Werkman, Ben R.},\n\tmonth = apr,\n\tyear = {2000},\n\tnote = {00023},\n\tkeywords = {\\#nosource},\n\tpages = {63--76},\n}\n\n\n\n\n\n Abstract. A new spatial simulation model of vegetation dynamics, called ‘VegeTate’, was applied to relationships between expansion of bracken (Pteridium aquili\n
\n\n\n\n \n\n \n \n \n \n \n \n Quantitative inferences of past hypolimnetic anoxia and nutrient levels from a Canadan Precambrian Shield lake.\n \n \n \n \n\n\n \n Clerk, S.; Hall, R.; Quinlan, R.; and Smol, J. P.\n\n\n \n\n\n\n Journal of Paleolimnology, 23(3): 319–336. March 2000.\n 00097\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{clerk_quantitative_2000,\n\ttitle = {Quantitative inferences of past hypolimnetic anoxia and nutrient levels from a {Canadan} {Precambrian} {Shield} lake},\n\tvolume = {23},\n\tissn = {0921-2728, 1573-0417},\n\turl = {https://link.springer.com/article/10.1023/A:1008147127606},\n\tdoi = {10.1023/A:1008147127606},\n\tabstract = {Paleolimnological analyses were used to infer limnological changes during the past {\\textasciitilde} 300 yrs in the west basin of Peninsula Lake, a small (853 ha) Precambrian Shield lake in Ontario, Canada, that has been subjected to moderate cultural disturbances (forest clearance, cottage and resort development). This study represents a pioneering attempt to use sedimentary chironomid assemblages and weighted-averaging models to quantify past hypolimnetic anoxia (expressed as the anoxic factor, AF). Impacts of forest clearance and human land-use on deepwater oxygen availability and surface water quality were assessed by comparing chironomid-inferred AF and diatom-inferred total phosphorus concentration ([TP]) to changes in terrestrial pollen and historical data. This study also discusses the ability of chironomids to quantitatively infer changes in AF.Pre-disturbance chironomid assemblages were stable and dominated by taxa indicative of oxygen-rich hypolimnetic conditions (e.g., Protanypus, Heterotrissocladius, Micropsectra type), while diatoms indicated oligotrophic lake status (diatom inferred [TP] = 5-7 μg·l-1). Chironomids characteristic of lower oxygen availability (e.g., Chironomus, Procladius) increased following land-clearance, road construction, establishment of a grist mill and lakeshore development beginning ca. 1870. Increased abundances of Tanytarsus s. lat., a multigeneric group of mainly littoral chironomids, since 1900, indicated that littoral chironomids may have comprised a greater proportion of fossil assemblages during periods of eutrophication and prolonged anoxia. Abundances of meso-eutrophic diatom taxa (e.g., Fragilaria crotonensis, Asterionella formosa, Aulacoseira ambigua, A. subarctica) increased concurrent with European settlement (ca. 1870) and diatom-inferred [TP] doubled ({\\textasciitilde} 6-12 μg·l-1), further indicating that naturally-oligotrophic Precambrian Shield lakes were extremely sensitive to initial land-clearance activities.Recent increases in oligotrophic diatom taxa (e.g., Cyclotella stelligera) indicate a shift to more oligotrophic conditions since ca. mid-1960s, with greatest changes since ca. 1980. The chironomids Heterotrissocladius and Micropsectra type also increased at this time suggesting greater deepwater oxygen availability. These recent water-quality improvements, possibly in response to enhanced nutrient removal from detergents and sewage, climate-related reductions in external phosphorus loads, and catchment (but not lake) acidification and reforestation, suggest that habitat for commercially-valuable cold-water fishes has improved in recent decades despite greater recreational lake-use.Paleolimnological assessment of trophic status changes in Peninsula Lake using fossil diatom and chironomid assemblages were in good agreement. Diatom inferences of [TP] and chironomid inferences of AF both suggest that Peninsula Lake was historically oligotrophic, became oligo-mesotrophic after European settlement, and returned to oligotrophy in recent yrs. Chironomid inferences of [TP] consistently underestimated the trophic status of Peninsula Lake, possibly due to its relatively large hypolimnion. These results suggest that AF represents a useful tool for quantitatively reconstructing the past trophic status of deeper, stratified lakes.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2018-06-11},\n\tjournal = {Journal of Paleolimnology},\n\tauthor = {Clerk, Saloni and Hall, Roland and Quinlan, Roberto and Smol, John P.},\n\tmonth = mar,\n\tyear = {2000},\n\tnote = {00097},\n\tkeywords = {\\#nosource},\n\tpages = {319--336},\n}\n\n\n\n\n\n Paleolimnological analyses were used to infer limnological changes during the past ~ 300 yrs in the west basin of Peninsula Lake, a small (853 ha) Precambrian Shield lake in Ontario, Canada, that has been subjected to moderate cultural disturbances (forest clearance, cottage and resort development). This study represents a pioneering attempt to use sedimentary chironomid assemblages and weighted-averaging models to quantify past hypolimnetic anoxia (expressed as the anoxic factor, AF). Impacts of forest clearance and human land-use on deepwater oxygen availability and surface water quality were assessed by comparing chironomid-inferred AF and diatom-inferred total phosphorus concentration ([TP]) to changes in terrestrial pollen and historical data. This study also discusses the ability of chironomids to quantitatively infer changes in AF.Pre-disturbance chironomid assemblages were stable and dominated by taxa indicative of oxygen-rich hypolimnetic conditions (e.g., Protanypus, Heterotrissocladius, Micropsectra type), while diatoms indicated oligotrophic lake status (diatom inferred [TP] = 5-7 μg·l-1). Chironomids characteristic of lower oxygen availability (e.g., Chironomus, Procladius) increased following land-clearance, road construction, establishment of a grist mill and lakeshore development beginning ca. 1870. Increased abundances of Tanytarsus s. lat., a multigeneric group of mainly littoral chironomids, since 1900, indicated that littoral chironomids may have comprised a greater proportion of fossil assemblages during periods of eutrophication and prolonged anoxia. Abundances of meso-eutrophic diatom taxa (e.g., Fragilaria crotonensis, Asterionella formosa, Aulacoseira ambigua, A. subarctica) increased concurrent with European settlement (ca. 1870) and diatom-inferred [TP] doubled (~ 6-12 μg·l-1), further indicating that naturally-oligotrophic Precambrian Shield lakes were extremely sensitive to initial land-clearance activities.Recent increases in oligotrophic diatom taxa (e.g., Cyclotella stelligera) indicate a shift to more oligotrophic conditions since ca. mid-1960s, with greatest changes since ca. 1980. The chironomids Heterotrissocladius and Micropsectra type also increased at this time suggesting greater deepwater oxygen availability. These recent water-quality improvements, possibly in response to enhanced nutrient removal from detergents and sewage, climate-related reductions in external phosphorus loads, and catchment (but not lake) acidification and reforestation, suggest that habitat for commercially-valuable cold-water fishes has improved in recent decades despite greater recreational lake-use.Paleolimnological assessment of trophic status changes in Peninsula Lake using fossil diatom and chironomid assemblages were in good agreement. Diatom inferences of [TP] and chironomid inferences of AF both suggest that Peninsula Lake was historically oligotrophic, became oligo-mesotrophic after European settlement, and returned to oligotrophy in recent yrs. Chironomid inferences of [TP] consistently underestimated the trophic status of Peninsula Lake, possibly due to its relatively large hypolimnion. These results suggest that AF represents a useful tool for quantitatively reconstructing the past trophic status of deeper, stratified lakes.\n
\n\n\n\n \n\n \n \n \n \n \n \n Past trophic status and hypolimnetic anoxia during eutrophicaton and remediation of Gravenhurst Bay, Ontario: comparison of diatoms, chironomids, and historical records.\n \n \n \n \n\n\n \n Little, J. L; Hall, R. I; Quinlan, R.; and Smol, J. P\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences, 57(2): 333–341. February 2000.\n 00084\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{little_past_2000,\n\ttitle = {Past trophic status and hypolimnetic anoxia during eutrophicaton and remediation of {Gravenhurst} {Bay}, {Ontario}: comparison of diatoms, chironomids, and historical records},\n\tvolume = {57},\n\tissn = {0706-652X},\n\tshorttitle = {Past trophic status and hypolimnetic anoxia during eutrophicaton and remediation of {Gravenhurst} {Bay}, {Ontario}},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/f99-235},\n\tdoi = {10.1139/f99-235},\n\tabstract = {Quantitative paleolimnological inferences of diatom-inferred total phosphorus and chironomid-inferred hypolimnetic oxygen levels (measured as the anoxic factor) were compared along with historical records for Gravenhurst Bay, Ontario, prior to and following sewage treatment. Water quality declined dramatically following European settlement in the mid-1800s and reached its highest inferred nutrient concentrations during the first half of the twentieth century. After treatment of sewage began in 1972, surface water total phosphorus rapidly returned to near oligotrophic conditions. Diatom assemblages reflected the period of nutrient enrichment, as well as the subsequent recovery. Chironomid assemblages exhibited trends consistent with decreased availability of dissolved oxygen to deepwater habitats since ca. 1886, with profundal taxa being largely absent since ca. 1958 when deepwater anoxia became more severe. Despite remediation efforts, Gravenhurst Bay still experiences long periods of anoxia, and chironom..., On a comparé des inférences paléolimnologiques quantitatives des concentrations de phosphore total (PT), établies à partir des assemblages de diatomées, et des niveaux d'oxygène (reflétés par le facteur anoxique, FA), établies à partir des assemblages de chironomides, avec des données historiques pour la baie Gravenhurst (Ontario) recueillies avant et après traitement des eaux usées. La qualité de l'eau a grandement diminué après l'établissement des populations d'origine européenne dans cette région au milieu du XIXe siècle, les concentrations de nutriants y ayant culminé selon nos inférences durant la première moitié du XXe siècle. Après l'instauration du traitement des eaux usées en 1972, les concentrations de PT dans les eaux de surface ont diminué pour revenir à des niveaux correspondant presque à ceux d'un milieu oligotrophe. Les assemblages de diatomées reflétaient la période d'enrichissement en nutriants, ainsi que le rétablissement subséquent. Les tendances des assemblages de chironomides reflétai...},\n\tnumber = {2},\n\turldate = {2018-06-11},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Little, Joanne L and Hall, Roland I and Quinlan, Roberto and Smol, John P},\n\tmonth = feb,\n\tyear = {2000},\n\tnote = {00084},\n\tkeywords = {\\#nosource},\n\tpages = {333--341},\n}\n\n\n\n\n\n Quantitative paleolimnological inferences of diatom-inferred total phosphorus and chironomid-inferred hypolimnetic oxygen levels (measured as the anoxic factor) were compared along with historical records for Gravenhurst Bay, Ontario, prior to and following sewage treatment. Water quality declined dramatically following European settlement in the mid-1800s and reached its highest inferred nutrient concentrations during the first half of the twentieth century. After treatment of sewage began in 1972, surface water total phosphorus rapidly returned to near oligotrophic conditions. Diatom assemblages reflected the period of nutrient enrichment, as well as the subsequent recovery. Chironomid assemblages exhibited trends consistent with decreased availability of dissolved oxygen to deepwater habitats since ca. 1886, with profundal taxa being largely absent since ca. 1958 when deepwater anoxia became more severe. Despite remediation efforts, Gravenhurst Bay still experiences long periods of anoxia, and chironom..., On a comparé des inférences paléolimnologiques quantitatives des concentrations de phosphore total (PT), établies à partir des assemblages de diatomées, et des niveaux d'oxygène (reflétés par le facteur anoxique, FA), établies à partir des assemblages de chironomides, avec des données historiques pour la baie Gravenhurst (Ontario) recueillies avant et après traitement des eaux usées. La qualité de l'eau a grandement diminué après l'établissement des populations d'origine européenne dans cette région au milieu du XIXe siècle, les concentrations de nutriants y ayant culminé selon nos inférences durant la première moitié du XXe siècle. Après l'instauration du traitement des eaux usées en 1972, les concentrations de PT dans les eaux de surface ont diminué pour revenir à des niveaux correspondant presque à ceux d'un milieu oligotrophe. Les assemblages de diatomées reflétaient la période d'enrichissement en nutriants, ainsi que le rétablissement subséquent. Les tendances des assemblages de chironomides reflétai...\n
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\n \n \n\n \n \n \n \n \n \n The Role of \"Natural\" Landscapes Influenced by Man in Predicting Responses to Climate Change.\n \n \n \n \n\n\n \n Hofgaard, A.\n\n\n \n\n\n\n Ecological Bulletins, 47: 160–167. January 1999.\n \n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{hofgaard_role_1999,\n\ttitle = {The {Role} of "{Natural}" {Landscapes} {Influenced} by {Man} in {Predicting} {Responses} to {Climate} {Change}},\n\tvolume = {47},\n\tcopyright = {Copyright © 1999 Oikos Editorial Office},\n\tissn = {0346-6868},\n\turl = {http://www.jstor.org/stable/20113238},\n\tabstract = {Large and small scale changes of the world's ecosystems are continuously occurring as responses to global change. In the northern boreal ecosystems this process has caused both species appearance and disappearance throughout the Holocene. However, the main effects have been structural changes, including altered distribution limits of species and shifts in species dominance. This paper focuses on natural and anthropogenic structural changes in the forest-tundra ecotone, mainly from a vegetation point of view. Specific examples are given from the Abisko area in northern Sweden, which has a long history of human impact. Land use changes during last centuries have caused large structural changes within the birch and pine forests, within the forest-tundra ecotone, and in tundra areas. These changes have impacted patterns of animal occurrence, site frequentation by animals, foraging behaviour, and on how animals influence the vegetation. The dynamic nature of structural changes and delayed responses are discussed in relation to different episodic and chronic disturbances. Time spans needed to recreate a structure comparable to the structure prior to a disturbance can not be known and can not be compared between different periods in time, as every time period is unique. Nevertheless, such time spans have to be taken into account when discussing management issues and future responses of the ecosystems.},\n\turldate = {2015-10-04},\n\tjournal = {Ecological Bulletins},\n\tauthor = {Hofgaard, Annika},\n\tmonth = jan,\n\tyear = {1999},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {160--167},\n}\n\n\n\n\n\n Large and small scale changes of the world's ecosystems are continuously occurring as responses to global change. In the northern boreal ecosystems this process has caused both species appearance and disappearance throughout the Holocene. However, the main effects have been structural changes, including altered distribution limits of species and shifts in species dominance. This paper focuses on natural and anthropogenic structural changes in the forest-tundra ecotone, mainly from a vegetation point of view. Specific examples are given from the Abisko area in northern Sweden, which has a long history of human impact. Land use changes during last centuries have caused large structural changes within the birch and pine forests, within the forest-tundra ecotone, and in tundra areas. These changes have impacted patterns of animal occurrence, site frequentation by animals, foraging behaviour, and on how animals influence the vegetation. The dynamic nature of structural changes and delayed responses are discussed in relation to different episodic and chronic disturbances. Time spans needed to recreate a structure comparable to the structure prior to a disturbance can not be known and can not be compared between different periods in time, as every time period is unique. Nevertheless, such time spans have to be taken into account when discussing management issues and future responses of the ecosystems.\n
\n\n\n\n \n\n \n \n \n \n \n \n Scenarios for Animal Responses to Global Change in Europe's Cold Regions: An Introduction.\n \n \n \n \n\n\n \n Danell, K.; Hofgaard, A.; Callaghan, T. V.; and Ball, J. P.\n\n\n \n\n\n\n Ecological Bulletins, 47: 8–15. January 1999.\n 00009\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{danell_scenarios_1999,\n\ttitle = {Scenarios for {Animal} {Responses} to {Global} {Change} in {Europe}'s {Cold} {Regions}: {An} {Introduction}},\n\tvolume = {47},\n\tcopyright = {Copyright © 1999 Oikos Editorial Office},\n\tissn = {0346-6868},\n\tshorttitle = {Scenarios for {Animal} {Responses} to {Global} {Change} in {Europe}'s {Cold} {Regions}},\n\turl = {http://www.jstor.org/stable/20113221},\n\tabstract = {00009},\n\turldate = {2015-10-04},\n\tjournal = {Ecological Bulletins},\n\tauthor = {Danell, Kjell and Hofgaard, Annika and Callaghan, Terry V. and Ball, John P.},\n\tmonth = jan,\n\tyear = {1999},\n\tnote = {00009},\n\tkeywords = {\\#nosource, ⛔ No DOI found},\n\tpages = {8--15},\n}\n\n\n\n\n\n 00009\n
\n\n\n\n \n\n \n \n \n \n \n The Tarfala mass balance programme.\n \n \n \n\n\n \n Holmlund, P.; and Jansson, P.\n\n\n \n\n\n\n Geografiska Annaler, 81A: 621–631. 1999.\n \n\n\n\n
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\n\n\n@article{holmlund_tarfala_1999,\n\ttitle = {The {Tarfala} mass balance programme},\n\tvolume = {81A},\n\tdoi = {10.1111/j.0435-3676.1999.00090.x},\n\tabstract = {The Tarfala mass balance programme currently comprises seven glaciers distributed in two, one southerly and one northerly, east–west trending profiles. Of the studied glaciers, Storglaciären has the longest record spanning 1945 to present. The purpose of the programme is to study gradients in mass balance parameters across the northern Scandinavian mountains. The measurements of both winter and summer balance are carried out with significant redundancy each year. In order to maintain such a large programme with limited personnel, different measurement techniques and strategies are applied to the different glaciers according to a priority scale. Storglaciären is the most important glacier in the network and is measured with high accuracy and measurement density. Storglaciären is also used as a reference for all other glaciers in the programme. The other glaciers have sparser measurement systems and are sometimes measured using alternative methods such as snow radar. In general, Swedish glaciers are still responding to the major climatic warming around 1910–1920 by retreat, and the effect of very long response times. However, measured volume change indicates that most glaciers are close to or varying around a quasi-steady state.},\n\tlanguage = {en},\n\tjournal = {Geografiska Annaler},\n\tauthor = {Holmlund, Per and Jansson, Peter},\n\tyear = {1999},\n\tkeywords = {\\#nosource},\n\tpages = {621--631},\n}\n\n\n\n\n\n The Tarfala mass balance programme currently comprises seven glaciers distributed in two, one southerly and one northerly, east–west trending profiles. Of the studied glaciers, Storglaciären has the longest record spanning 1945 to present. The purpose of the programme is to study gradients in mass balance parameters across the northern Scandinavian mountains. The measurements of both winter and summer balance are carried out with significant redundancy each year. In order to maintain such a large programme with limited personnel, different measurement techniques and strategies are applied to the different glaciers according to a priority scale. Storglaciären is the most important glacier in the network and is measured with high accuracy and measurement density. Storglaciären is also used as a reference for all other glaciers in the programme. The other glaciers have sparser measurement systems and are sometimes measured using alternative methods such as snow radar. In general, Swedish glaciers are still responding to the major climatic warming around 1910–1920 by retreat, and the effect of very long response times. However, measured volume change indicates that most glaciers are close to or varying around a quasi-steady state.\n
\n\n\n\n \n\n \n \n \n \n \n \n The effects of plant litter on vegetation: a meta-analysis.\n \n \n \n \n\n\n \n Xiong, S.; and Nilsson, C.\n\n\n \n\n\n\n Journal of Ecology, 87(6): 984–994. 1999.\n \n\n\n\n
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\n\n\n@article{xiong_effects_1999,\n\ttitle = {The effects of plant litter on vegetation: a meta-analysis},\n\tvolume = {87},\n\tissn = {1365-2745},\n\tshorttitle = {The effects of plant litter on vegetation},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2745.1999.00414.x},\n\tdoi = {10.1046/j.1365-2745.1999.00414.x},\n\tabstract = {1 We used data from 35 independently published studies world-wide to analyse the effects of plant litter on the germination, establishment, species richness and above-ground biomass of plants. Overall, the short-term effects of litter on vegetation were mostly negative, although their magnitude varied with vegetation variable, study method, experimental duration, latitude, habitat, type and quantity of litter and target species. 2 Species richness was more affected than above-ground biomass by litter, suggesting that litter may play a direct role in structuring plant communities as well as influencing competition in productive habitats. Litter had a stronger overall effect on plant germination than on establishment, suggesting that a litter-reducing disturbance will have more effect early in the growth season. 3 On average, vegetation was more affected by litter in field than in glasshouse studies and during 2-year than during 1-year studies. The effect on biomass switched from negative after 1 year to positive after 3 years. 4 The absolute effects of litter on germination and establishment decreased and the absolute effects on above-ground biomass increased with latitude. Ecosystem type also influenced the effects significantly. 5 Vegetation was generally more depressed by higher litter quantities. Litter composed of forbs and tree leaves had a stronger effect on vegetation than grass litter. The impact of a certain type of litter may therefore be related to its decomposition rate. 6 Tree species were more affected than forbs and grasses by litter, at least at the colonization stage.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2019-03-27},\n\tjournal = {Journal of Ecology},\n\tauthor = {Xiong, Shaojun and Nilsson, Christer},\n\tyear = {1999},\n\tkeywords = {\\#nosource, above-ground biomass, ecosystem type, effect size, litter type and quantity, plant establishment, seed germination, species richness, study method and duration, target species},\n\tpages = {984--994},\n}\n\n\n\n\n\n 1 We used data from 35 independently published studies world-wide to analyse the effects of plant litter on the germination, establishment, species richness and above-ground biomass of plants. Overall, the short-term effects of litter on vegetation were mostly negative, although their magnitude varied with vegetation variable, study method, experimental duration, latitude, habitat, type and quantity of litter and target species. 2 Species richness was more affected than above-ground biomass by litter, suggesting that litter may play a direct role in structuring plant communities as well as influencing competition in productive habitats. Litter had a stronger overall effect on plant germination than on establishment, suggesting that a litter-reducing disturbance will have more effect early in the growth season. 3 On average, vegetation was more affected by litter in field than in glasshouse studies and during 2-year than during 1-year studies. The effect on biomass switched from negative after 1 year to positive after 3 years. 4 The absolute effects of litter on germination and establishment decreased and the absolute effects on above-ground biomass increased with latitude. Ecosystem type also influenced the effects significantly. 5 Vegetation was generally more depressed by higher litter quantities. Litter composed of forbs and tree leaves had a stronger effect on vegetation than grass litter. The impact of a certain type of litter may therefore be related to its decomposition rate. 6 Tree species were more affected than forbs and grasses by litter, at least at the colonization stage.\n
\n\n\n\n \n\n \n \n \n \n \n \n Dendroclimatic response of Picea mariana and Pinus banksiana along a latitudinal gradient in the eastern Canadian boreal forest.\n \n \n \n \n\n\n \n Hofgaard, A.; Tardif, J.; and Bergeron, Y.\n\n\n \n\n\n\n Canadian Journal of Forest Research, 29(9): 1333–1346. September 1999.\n 00133\n\n\n\n
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\n\n\n@article{hofgaard_dendroclimatic_1999,\n\ttitle = {Dendroclimatic response of {Picea} mariana and {Pinus} banksiana along a latitudinal gradient in the eastern {Canadian} boreal forest},\n\tvolume = {29},\n\tissn = {0045-5067},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/x99-073},\n\tdoi = {10.1139/x99-073},\n\tabstract = {To decipher spatial and temporal tree-growth responses to climate change we used tree-ring data from Picea mariana (Mill.) BSP and Pinus banksiana Lamb. along a latitudinal transect in western Quebec. The transect encompassed the distinct transition between mixed and coniferous forests at approximately 49°N. Correlation analyses and principal component analyses were used to identify common spatiotemporal growth patterns, and site- and species-specific patterns since 1825. A moist summer in the year t - 1 and an early start of the current growing season favored growth of both species. A prolongation of the growing season into fall was the most distinguishing factor between the species. A long and gradual climatic gradient shifted to a short gradient with a clear segregation between the southern and northern parts of the transect. This shift, around 1875, was abrupt and characterized by a turbulent climatic period. The observed pattern was likely related to a large-scale shift in the mean position of the Ar..., À l'aide d'une approche dendrochronologique, nous avons étudié les effets spatio-temporels des changements climatiques sur la croissance radiale de Picea mariana (Mill.) BSP et Pinus banksiana Lamb. selon un gradient latitudinal dans l'ouest du Québec. Le transect inclut, près du 49° de latitude N., une transition abrupte entre la forêt mixte et la forêt coniférienne. Des analyses de corrélations ainsi qu'en composantes principales sont utilisées pour mettre en évidence, depuis 1825, les patrons de croissance spatio-temporels communs, ainsi que les changements plus spécifiques aux sites et aux espèces. La croissance des deux espèces est favorisée par des étés humides à l'année t - 1 et par un début hâtif de la saison de croissance durant l'année courante. Un allongement de la période de croissance durant l'automne est le principal facteur qui distingue les deux espèces. Une transition climatique graduelle du sud au nord a fait place à un gradient plus court discriminant les portions sud et nord du transec...},\n\tnumber = {9},\n\turldate = {2018-06-08},\n\tjournal = {Canadian Journal of Forest Research},\n\tauthor = {Hofgaard, Annika and Tardif, Jacques and Bergeron, Yves},\n\tmonth = sep,\n\tyear = {1999},\n\tnote = {00133},\n\tkeywords = {\\#nosource},\n\tpages = {1333--1346},\n}\n\n\n\n\n\n To decipher spatial and temporal tree-growth responses to climate change we used tree-ring data from Picea mariana (Mill.) BSP and Pinus banksiana Lamb. along a latitudinal transect in western Quebec. The transect encompassed the distinct transition between mixed and coniferous forests at approximately 49°N. Correlation analyses and principal component analyses were used to identify common spatiotemporal growth patterns, and site- and species-specific patterns since 1825. A moist summer in the year t - 1 and an early start of the current growing season favored growth of both species. A prolongation of the growing season into fall was the most distinguishing factor between the species. A long and gradual climatic gradient shifted to a short gradient with a clear segregation between the southern and northern parts of the transect. This shift, around 1875, was abrupt and characterized by a turbulent climatic period. The observed pattern was likely related to a large-scale shift in the mean position of the Ar..., À l'aide d'une approche dendrochronologique, nous avons étudié les effets spatio-temporels des changements climatiques sur la croissance radiale de Picea mariana (Mill.) BSP et Pinus banksiana Lamb. selon un gradient latitudinal dans l'ouest du Québec. Le transect inclut, près du 49° de latitude N., une transition abrupte entre la forêt mixte et la forêt coniférienne. Des analyses de corrélations ainsi qu'en composantes principales sont utilisées pour mettre en évidence, depuis 1825, les patrons de croissance spatio-temporels communs, ainsi que les changements plus spécifiques aux sites et aux espèces. La croissance des deux espèces est favorisée par des étés humides à l'année t - 1 et par un début hâtif de la saison de croissance durant l'année courante. Un allongement de la période de croissance durant l'automne est le principal facteur qui distingue les deux espèces. Une transition climatique graduelle du sud au nord a fait place à un gradient plus court discriminant les portions sud et nord du transec...\n
\n\n\n\n \n\n \n \n \n \n \n \n Effects of increased temperature and nitrogen availability on the displacement of Calluna vulgaris by Pteridium aquilinum.\n \n \n \n \n\n\n \n Werkman, B. R.; and Callaghan, T. V.\n\n\n \n\n\n\n Applied Vegetation Science, 2(2): 201–208. 1999.\n 00007\n\n\n\n
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\n\n\n@article{werkman_effects_1999,\n\ttitle = {Effects of increased temperature and nitrogen availability on the displacement of {Calluna} vulgaris by {Pteridium} aquilinum},\n\tvolume = {2},\n\tcopyright = {1999 IAVS ‐ the International Association of Vegetation Science},\n\tissn = {1654-109X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.2307/1478983},\n\tdoi = {10.2307/1478983},\n\tabstract = {Abstract. Atmospheric greenhouse gas concentrations will continue to rise for the foreseeable future, and, due to radiative forcing, surface temperatures will also increase. If soils warm sufficiently, this will result in increased litter decomposition rates, while nitrogen availability will also rise due to increased deposition. A field-based experiment manipulating air temperatures using polythene tents and nitrogen availability by adding 50 kg N ha-1 yr-1 has shown that this will result in further encroachment of Pteridium into Calluna moorland. Although this experiment, treating plots on and around the boundary between Pteridium and Calluna, did not show any statistically significant effect on the movement of the boundary, there were clear indications of Calluna dieback at the boundary. In addition, the frequency of Pteridium fronds increased in the Calluna-dominated areas, while Calluna became less abundant in the pure Pteridium plots. Calluna dieback was not due to litter accumulation as is frequently assumed, but the dieback is likely to be caused by shading of Calluna by the increased growth of Pteridium fronds. Botanical diversity was higher in the Pteridium plots, but considering the importance of grouse shooting for the maintenance of Calluna moorland, displacement of Calluna by Pteridium may result in a lower conservation and economic value of moorlands.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2018-06-08},\n\tjournal = {Applied Vegetation Science},\n\tauthor = {Werkman, Ben R. and Callaghan, Terry V.},\n\tyear = {1999},\n\tnote = {00007},\n\tkeywords = {\\#nosource, Boundary, Bracken, Global change, Heather, Increased nitrogen availability, Increased temperature},\n\tpages = {201--208},\n}\n\n\n\n\n\n Abstract. Atmospheric greenhouse gas concentrations will continue to rise for the foreseeable future, and, due to radiative forcing, surface temperatures will also increase. If soils warm sufficiently, this will result in increased litter decomposition rates, while nitrogen availability will also rise due to increased deposition. A field-based experiment manipulating air temperatures using polythene tents and nitrogen availability by adding 50 kg N ha-1 yr-1 has shown that this will result in further encroachment of Pteridium into Calluna moorland. Although this experiment, treating plots on and around the boundary between Pteridium and Calluna, did not show any statistically significant effect on the movement of the boundary, there were clear indications of Calluna dieback at the boundary. In addition, the frequency of Pteridium fronds increased in the Calluna-dominated areas, while Calluna became less abundant in the pure Pteridium plots. Calluna dieback was not due to litter accumulation as is frequently assumed, but the dieback is likely to be caused by shading of Calluna by the increased growth of Pteridium fronds. Botanical diversity was higher in the Pteridium plots, but considering the importance of grouse shooting for the maintenance of Calluna moorland, displacement of Calluna by Pteridium may result in a lower conservation and economic value of moorlands.\n
\n\n\n\n \n\n \n \n \n \n \n \n Limnological succession in reservoirs: a paleolimnological comparison of two methods of reservoir formation.\n \n \n \n \n\n\n \n Hall, R. I; Leavitt, P. R; Dixit, A. S; Quinlan, R.; and Smol, J. P\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences, 56(6): 1109–1121. June 1999.\n 00067\n\n\n\n
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\n\n\n@article{hall_limnological_1999,\n\ttitle = {Limnological succession in reservoirs: a paleolimnological comparison of two methods of reservoir formation},\n\tvolume = {56},\n\tissn = {0706-652X},\n\tshorttitle = {Limnological succession in reservoirs},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/f99-047},\n\tdoi = {10.1139/f99-047},\n\tabstract = {Analysis of diatoms, algal pigments, and chironomids in sediment cores from two otherwise similar prairie reservoirs demonstrated that differences in reservoir formation (river valley impoundment versus lake inundation) and hydrological regime (variable versus stable water level) resulted in distinct patterns of aquatic community change. Lake Diefenbaker, a 500-km2 reservoir created by damming the South Saskatchewan River in 1968, experiences water level fluctuations of 6 m·year-1. In contrast, impoundment of Buffalo Pound Lake in 1952 flooded a natural lake, raised mean water levels {\\textasciitilde}2.0 m, and reduced water level fluctuations from {\\textasciitilde}3 to {\\textless}1 m·year-1. Comparison of fossil records showed that reservoir formation did not inevitably lead to eutrophication. Lake Diefenbaker exhibited typical reservoir ontogeny with three trophic periods, including an initial {\\textasciitilde}4-year period of eutrophy, a decade of mesotrophy, and a gradual shift to modern productive conditions. Planktonic taxa dominated diatom communities at ..., L'analyse des diatomées, des pigments algaux et des chironomides dans des carottes de sédiments de deux réservoirs de prairie semblables par ailleurs montre que les différences dans la formation des réservoirs (endiguement de rivière dans une vallée ou inondation d'un lac) et le régime hydrologique (niveau de l'eau variable ou stable) ont donné des profils distincts de changement dans les communautés aquatiques. Au lac Diefenbaker, un réservoir de 500 km2 créé par l'endiguement de la rivière Saskatchewan Sud en 1968, on observe des fluctuations du niveau de l'eau de 6 m·an-1. Par contre, l'endiguement du lac Buffalo Pound en 1952 a agrandi ce lac naturel et élevé le niveau moyen de l'eau d'environ 2,0 m tout en réduisant les fluctuations du niveau d'environ 3 m·an-1 à moins de 1 m·an-1. La comparaison des registres fossiles a montré que la formation d'un réservoir ne conduit pas nécessairement à une eutrophisation. On a observé au lac Diefenbaker une ontogénie typique de réservoir avec trois périodes trop...},\n\tnumber = {6},\n\turldate = {2018-06-08},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Hall, Roland I and Leavitt, Peter R and Dixit, Aruna S and Quinlan, Roberto and Smol, John P},\n\tmonth = jun,\n\tyear = {1999},\n\tnote = {00067},\n\tkeywords = {\\#nosource},\n\tpages = {1109--1121},\n}\n\n\n\n\n\n Analysis of diatoms, algal pigments, and chironomids in sediment cores from two otherwise similar prairie reservoirs demonstrated that differences in reservoir formation (river valley impoundment versus lake inundation) and hydrological regime (variable versus stable water level) resulted in distinct patterns of aquatic community change. Lake Diefenbaker, a 500-km2 reservoir created by damming the South Saskatchewan River in 1968, experiences water level fluctuations of 6 m·year-1. In contrast, impoundment of Buffalo Pound Lake in 1952 flooded a natural lake, raised mean water levels ~2.0 m, and reduced water level fluctuations from ~3 to \\textless1 m·year-1. Comparison of fossil records showed that reservoir formation did not inevitably lead to eutrophication. Lake Diefenbaker exhibited typical reservoir ontogeny with three trophic periods, including an initial ~4-year period of eutrophy, a decade of mesotrophy, and a gradual shift to modern productive conditions. Planktonic taxa dominated diatom communities at ..., L'analyse des diatomées, des pigments algaux et des chironomides dans des carottes de sédiments de deux réservoirs de prairie semblables par ailleurs montre que les différences dans la formation des réservoirs (endiguement de rivière dans une vallée ou inondation d'un lac) et le régime hydrologique (niveau de l'eau variable ou stable) ont donné des profils distincts de changement dans les communautés aquatiques. Au lac Diefenbaker, un réservoir de 500 km2 créé par l'endiguement de la rivière Saskatchewan Sud en 1968, on observe des fluctuations du niveau de l'eau de 6 m·an-1. Par contre, l'endiguement du lac Buffalo Pound en 1952 a agrandi ce lac naturel et élevé le niveau moyen de l'eau d'environ 2,0 m tout en réduisant les fluctuations du niveau d'environ 3 m·an-1 à moins de 1 m·an-1. La comparaison des registres fossiles a montré que la formation d'un réservoir ne conduit pas nécessairement à une eutrophisation. On a observé au lac Diefenbaker une ontogénie typique de réservoir avec trois périodes trop...\n
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\n \n \n\n \n \n \n \n \n \n Fructans interact strongly with model membranes.\n \n \n \n \n\n\n \n Demel, R. A.; Dorrepaal, E.; Ebskamp, M. J. M.; Smeekens, J. C. M.; and de Kruijff, B.\n\n\n \n\n\n\n Biochimica et Biophysica Acta (BBA) - Biomembranes, 1375(1): 36–42. October 1998.\n 00090\n\n\n\n
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\n\n\n@article{demel_fructans_1998,\n\ttitle = {Fructans interact strongly with model membranes},\n\tvolume = {1375},\n\tissn = {0005-2736},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0005273698001382},\n\tdoi = {10.1016/S0005-2736(98)00138-2},\n\tabstract = {Bacterial fructans with a high degree of polymerisation cause a very large increase in surface pressure of lipid monolayers at the air–water interface with a broad range of lipids, including phosphatidylethanolamine and several types of phosphatidylcholines. The surface active effect of fructans contrasts strongly with the maximal effects observed for trehalose, sucrose and glucose under comparable conditions (20 and 0.6 mN/m for fructans and the other sugars, respectively). The results demonstrate a profound and specific membrane interaction of the fructans which is probably very different from the effect of the smaller carbohydrates. The fructan concentrations used in this study are within the physiological range observed in fructan-accumulating plants. The suggested water-stress protective effect of fructans may be induced by membrane–fructan interaction which prevent lipid condensation and phase transitions to take place.},\n\tnumber = {1},\n\turldate = {2018-09-17},\n\tjournal = {Biochimica et Biophysica Acta (BBA) - Biomembranes},\n\tauthor = {Demel, R. A. and Dorrepaal, E. and Ebskamp, M. J. M. and Smeekens, J. C. M. and de Kruijff, B.},\n\tmonth = oct,\n\tyear = {1998},\n\tnote = {00090},\n\tkeywords = {\\#nosource, Carbohydrate, Desiccation, Fructan, Monomolecular layer, Phase transition, Phospholipid},\n\tpages = {36--42},\n}\n\n\n\n\n\n Bacterial fructans with a high degree of polymerisation cause a very large increase in surface pressure of lipid monolayers at the air–water interface with a broad range of lipids, including phosphatidylethanolamine and several types of phosphatidylcholines. The surface active effect of fructans contrasts strongly with the maximal effects observed for trehalose, sucrose and glucose under comparable conditions (20 and 0.6 mN/m for fructans and the other sugars, respectively). The results demonstrate a profound and specific membrane interaction of the fructans which is probably very different from the effect of the smaller carbohydrates. The fructan concentrations used in this study are within the physiological range observed in fructan-accumulating plants. The suggested water-stress protective effect of fructans may be induced by membrane–fructan interaction which prevent lipid condensation and phase transitions to take place.\n
\n\n\n\n \n\n \n \n \n \n \n \n Quantitative inferences of past hypolimnetic anoxia in south-central Ontario lakes using fossil midges (Diptera: Chironomidae).\n \n \n \n \n\n\n \n Quinlan, R.; Smol, J. P; and Hall, R. I\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences, 55(3): 587–596. March 1998.\n 00134\n\n\n\n
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\n\n\n@article{quinlan_quantitative_1998,\n\ttitle = {Quantitative inferences of past hypolimnetic anoxia in south-central {Ontario} lakes using fossil midges ({Diptera}: {Chironomidae})},\n\tvolume = {55},\n\tissn = {0706-652X},\n\tshorttitle = {Quantitative inferences of past hypolimnetic anoxia in south-central {Ontario} lakes using fossil midges ({Diptera}},\n\turl = {http://www.nrcresearchpress.com/doi/abs/10.1139/f97-279},\n\tdoi = {10.1139/f97-279},\n\tabstract = {The ability to infer long-term changes in hypolimnetic oxygen levels is important for ecological studies of eutrophication and the impacts of climatic change on freshwater lakes. We examined the distributions of fossil midge (Diptera: Chironomidae) assemblages in the surface sediments of 54 south-central Ontario lakes and, using canonical correspondence analysis (CCA), determined if fossil chironomid assemblages could be used to reconstruct levels of hypolimnetic anoxia in thermally stratifying Laurentian Shield lakes. Anoxia was expressed as the anoxic factor (AF), which represents the days per season that a sediment area equal to a lake's surface area is overlain by anoxic water. Forward selection in CCA showed that AF, maximum depth, [SO4], [Na], and watershed area all explained significant portions of species variation. A weighted-averaging regression and calibration model of the chironomid-anoxia relationship was developed which suggests that it is possible to infer AF from fossil chironomid assembla..., La capacité de modifier à long terme la teneur en oxygène dans l'hypolimnion est importante pour les études écologiques sur l'eutrophisation et les effets du changement climatique sur les lacs d'eau douce. Nous avons étudié la répartition d'assemblages de moucherons (Diptères : Chironomidés) fossiles dans les sédiments superficiels de 54 lacs du centre-sud de l'Ontario et, au moyen de l'analyse de correspondance canonique (ACC), nous avons déterminé si ces assemblages pouvaient être utilisés pour reproduire les niveaux d'anoxie de l'hypolimnion dans des lacs à stratification thermique du bouclier laurentien. L'anoxie était exprimée sous la forme du facteur d'anoxie (FA), qui correspond au nombre de jours par saison pendant lesquels une zone de sédiment de même superficie qu'un lac est recouverte d'eau anoxique. Une régression progressive dans l'ACC a montré que le FA, la profondeur maximale, [SO4], [Na] et la superficie du bassin hydrographique sont des éléments dont chacun rend compte d'une partie import...},\n\tnumber = {3},\n\turldate = {2018-06-08},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Quinlan, Roberto and Smol, John P and Hall, Roland I},\n\tmonth = mar,\n\tyear = {1998},\n\tnote = {00134},\n\tkeywords = {\\#nosource},\n\tpages = {587--596},\n}\n\n\n\n\n\n The ability to infer long-term changes in hypolimnetic oxygen levels is important for ecological studies of eutrophication and the impacts of climatic change on freshwater lakes. We examined the distributions of fossil midge (Diptera: Chironomidae) assemblages in the surface sediments of 54 south-central Ontario lakes and, using canonical correspondence analysis (CCA), determined if fossil chironomid assemblages could be used to reconstruct levels of hypolimnetic anoxia in thermally stratifying Laurentian Shield lakes. Anoxia was expressed as the anoxic factor (AF), which represents the days per season that a sediment area equal to a lake's surface area is overlain by anoxic water. Forward selection in CCA showed that AF, maximum depth, [SO4], [Na], and watershed area all explained significant portions of species variation. A weighted-averaging regression and calibration model of the chironomid-anoxia relationship was developed which suggests that it is possible to infer AF from fossil chironomid assembla..., La capacité de modifier à long terme la teneur en oxygène dans l'hypolimnion est importante pour les études écologiques sur l'eutrophisation et les effets du changement climatique sur les lacs d'eau douce. Nous avons étudié la répartition d'assemblages de moucherons (Diptères : Chironomidés) fossiles dans les sédiments superficiels de 54 lacs du centre-sud de l'Ontario et, au moyen de l'analyse de correspondance canonique (ACC), nous avons déterminé si ces assemblages pouvaient être utilisés pour reproduire les niveaux d'anoxie de l'hypolimnion dans des lacs à stratification thermique du bouclier laurentien. L'anoxie était exprimée sous la forme du facteur d'anoxie (FA), qui correspond au nombre de jours par saison pendant lesquels une zone de sédiment de même superficie qu'un lac est recouverte d'eau anoxique. Une régression progressive dans l'ACC a montré que le FA, la profondeur maximale, [SO4], [Na] et la superficie du bassin hydrographique sont des éléments dont chacun rend compte d'une partie import...\n
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\n \n \n\n \n \n \n \n \n \n Inter-Relationships between Treeline Position, Species Diversity, Land Use and Climate Change in the Central Scandes Mountains of Norway.\n \n \n \n \n\n\n \n Hofgaard, A.\n\n\n \n\n\n\n Global Ecology and Biogeography Letters, 6(6): 419–429. 1997.\n 00152\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{hofgaard_inter-relationships_1997,\n\ttitle = {Inter-{Relationships} between {Treeline} {Position}, {Species} {Diversity}, {Land} {Use} and {Climate} {Change} in the {Central} {Scandes} {Mountains} of {Norway}},\n\tvolume = {6},\n\tissn = {0960-7447},\n\turl = {http://www.jstor.org/stable/2997351},\n\tdoi = {10.2307/2997351},\n\tabstract = {Vegetation samples collected along altitudinal transects through the treeline ecotone in the central Scandes Mountains, Norway, were used to analyse the relationships between species diversity, species turnover and the performance of the tree layer. The study area has a long history of extensive grazing by domestic animals. The floristic composition showed a continuous change along the boreal-alpine gradient. The number of species was more or less constant throughout 600 altitudinal m centred around the treeline, and the floristic similarity between neighbouring altitudes did not show any abrupt changes at any particular altitude. The treeline position (Betula pubescens Ehrh.) spanned 190 altitudinal m (range 980-1170 m a.s.l.). The number of trees and the basal area each decreased continuously with increasing altitude from 300 altitudinal m below the treeline. The number of birch saplings also decreased from c. 150 m below the treeline towards higher altitudes. Viable, but browsed populations of birch were present along the whole length of all transects, irrespective of aspect and geological substrate, with saplings present up to summit positions at 420 altitudinal m above the treeline. Due to browsing by sheep, mean sapling height at all altitudes above the treeline was 0.2 m. The results are discussed in terms of land use and climate change. It is concluded that future vegetation responses to diminished grazing pressure are likely to override responses forced by changing climate. Such responses could easily be misinterpreted as being governed by climate change, rather than by changes in land use.},\n\tnumber = {6},\n\turldate = {2018-06-08},\n\tjournal = {Global Ecology and Biogeography Letters},\n\tauthor = {Hofgaard, Annika},\n\tyear = {1997},\n\tnote = {00152},\n\tkeywords = {\\#nosource},\n\tpages = {419--429},\n}\n\n\n\n\n\n Vegetation samples collected along altitudinal transects through the treeline ecotone in the central Scandes Mountains, Norway, were used to analyse the relationships between species diversity, species turnover and the performance of the tree layer. The study area has a long history of extensive grazing by domestic animals. The floristic composition showed a continuous change along the boreal-alpine gradient. The number of species was more or less constant throughout 600 altitudinal m centred around the treeline, and the floristic similarity between neighbouring altitudes did not show any abrupt changes at any particular altitude. The treeline position (Betula pubescens Ehrh.) spanned 190 altitudinal m (range 980-1170 m a.s.l.). The number of trees and the basal area each decreased continuously with increasing altitude from 300 altitudinal m below the treeline. The number of birch saplings also decreased from c. 150 m below the treeline towards higher altitudes. Viable, but browsed populations of birch were present along the whole length of all transects, irrespective of aspect and geological substrate, with saplings present up to summit positions at 420 altitudinal m above the treeline. Due to browsing by sheep, mean sapling height at all altitudes above the treeline was 0.2 m. The results are discussed in terms of land use and climate change. It is concluded that future vegetation responses to diminished grazing pressure are likely to override responses forced by changing climate. Such responses could easily be misinterpreted as being governed by climate change, rather than by changes in land use.\n
\n\n\n\n \n\n \n \n \n \n \n \n Comparison of diatoms, fossil pigments and historical records as measures of lake eutrophication.\n \n \n \n \n\n\n \n Hall, R.; Leavitt, P.; Smol, J.; and Zirnhelt, N.\n\n\n \n\n\n\n Freshwater Biology, 38(2): 401–417. October 1997.\n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n\n\n\n\n
\n\n\n@article{hall_comparison_1997,\n\ttitle = {Comparison of diatoms, fossil pigments and historical records as measures of lake eutrophication},\n\tvolume = {38},\n\tissn = {1365-2427},\n\turl = {http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2427.1997.00251.x/abstract},\n\tdoi = {10.1046/j.1365-2427.1997.00251.x},\n\tabstract = {1. Analysis of fossil diatoms and pigments was used to examine the effects of land-management practises on the trophic status of Williams Lake, a eutrophic lake in central British Columbia, Canada. Published weighted-average (WA) models were used to infer changes in total phosphorus concentration (TP) during the past 200 years. 2. Diatom-inferred TP (DI-TP) was compared to 20 years of direct chemical TP measurements to determine the accuracy of diatom-TP models in inferring mean summer TP in Williams Lake. Plant pigments were measured using high performance liquid chromatography (HPLC) to quantify historical changes in gross algal community composition and abundance and to evaluate further diatom-TP inferences. 3. Palaeolimnological analyses showed that Williams Lake has been productive throughout the last 200 years. Diatoms characteristic of alkaline, eutrophic conditions were continuously present c. 1765–1990 AD. Carotenoids from filamentous cyanobacteria (myxoxanthophyll, aphanizophyll) were regularly present in Williams Lake sediments, although cryptophytes (alloxanthin), diatoms (diatoxanthin), chlorophytes (lutein-zeaxanthin, b-phorbins), and siliceous algae (diatoms, chrysophytes) or dinoflagellates (fucoxanthin) were also important components of past algal communities. Terrestrial disturbance (railway and road constructions, cattle ranching) increased lake production, but resulted in relatively little permanent environmental change. 4. Comparison of DI-TP with measured TP (1972–91) showed that inferences from simple WA models were similar to average summer TP (39.1 vs. 35.2 μg TP l–1). Inferences resulting from data manipulations that down-weighted eutrophic lakes (outlier elimination, bootstrapping) or diatom species (square-root transformation, tolerance-weighting) were weakly and negatively correlated with measured TP, introduced bias into inference models, or underestimated measured TP. These patterns suggest that, when using diatom-TP models developed from sparsely populated regions, accurate palaeoecological inferences for TP in eutrophic lakes should avoid data manipulations which down-weight the most productive sites and taxa. 5. Comparison of DI-TP and fossil-inferred algal abundance during the past 200 years suggested that changes in nutrient inputs accounted for relatively little variation in past algal abundance. Although past changes in total algal biomass (as β-carotene) and DI-TP were broadly similar, the two variables were not significantly correlated (α = 0.05). In contrast, changes in DI-TP were significantly correlated with mean concentrations of diatom-specific carotenoids (diatoxanthin), although the explanatory power was low (r2 = 0.16). These patterns suggest that the DI-TP model reflects more closely environmental conditions in Williams Lake during periods of diatom growth, and not necessarily those when total algal biomass is greatest.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2017-02-07},\n\tjournal = {Freshwater Biology},\n\tauthor = {Hall, Roland and Leavitt, Peter and Smol, John and Zirnhelt, Norman},\n\tmonth = oct,\n\tyear = {1997},\n\tkeywords = {\\#nosource},\n\tpages = {401--417},\n}\n\n\n\n\n\n 1. Analysis of fossil diatoms and pigments was used to examine the effects of land-management practises on the trophic status of Williams Lake, a eutrophic lake in central British Columbia, Canada. Published weighted-average (WA) models were used to infer changes in total phosphorus concentration (TP) during the past 200 years. 2. Diatom-inferred TP (DI-TP) was compared to 20 years of direct chemical TP measurements to determine the accuracy of diatom-TP models in inferring mean summer TP in Williams Lake. Plant pigments were measured using high performance liquid chromatography (HPLC) to quantify historical changes in gross algal community composition and abundance and to evaluate further diatom-TP inferences. 3. Palaeolimnological analyses showed that Williams Lake has been productive throughout the last 200 years. Diatoms characteristic of alkaline, eutrophic conditions were continuously present c. 1765–1990 AD. Carotenoids from filamentous cyanobacteria (myxoxanthophyll, aphanizophyll) were regularly present in Williams Lake sediments, although cryptophytes (alloxanthin), diatoms (diatoxanthin), chlorophytes (lutein-zeaxanthin, b-phorbins), and siliceous algae (diatoms, chrysophytes) or dinoflagellates (fucoxanthin) were also important components of past algal communities. Terrestrial disturbance (railway and road constructions, cattle ranching) increased lake production, but resulted in relatively little permanent environmental change. 4. Comparison of DI-TP with measured TP (1972–91) showed that inferences from simple WA models were similar to average summer TP (39.1 vs. 35.2 μg TP l–1). Inferences resulting from data manipulations that down-weighted eutrophic lakes (outlier elimination, bootstrapping) or diatom species (square-root transformation, tolerance-weighting) were weakly and negatively correlated with measured TP, introduced bias into inference models, or underestimated measured TP. These patterns suggest that, when using diatom-TP models developed from sparsely populated regions, accurate palaeoecological inferences for TP in eutrophic lakes should avoid data manipulations which down-weight the most productive sites and taxa. 5. Comparison of DI-TP and fossil-inferred algal abundance during the past 200 years suggested that changes in nutrient inputs accounted for relatively little variation in past algal abundance. Although past changes in total algal biomass (as β-carotene) and DI-TP were broadly similar, the two variables were not significantly correlated (α = 0.05). In contrast, changes in DI-TP were significantly correlated with mean concentrations of diatom-specific carotenoids (diatoxanthin), although the explanatory power was low (r2 = 0.16). These patterns suggest that the DI-TP model reflects more closely environmental conditions in Williams Lake during periods of diatom growth, and not necessarily those when total algal biomass is greatest.\n
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\n \n \n\n \n \n \n \n \n \n Controlling biases in targeted plant removal experiments.\n \n \n \n \n\n\n \n Monteux, S.; Blume-Werry, G.; Gavazov, K.; Kirchhoff, L.; Krab, E. J.; Lett, S.; Pedersen, E. P.; and Väisänen, M.\n\n\n \n\n\n\n New Phytologist, n/a(n/a): 19386. .\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/nph.19386\n\n\n\n
\n\n\n\n \n \nPaper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n
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Paper\n \n \n\n \n \n doi\n \n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\n\n\n\n
\n\n\n@article{monteux_controlling_nodate,\n\ttitle = {Controlling biases in targeted plant removal experiments},\n\tvolume = {n/a},\n\tcopyright = {© 2023 The Authors. New Phytologist © 2023 New Phytologist Foundation},\n\tissn = {1469-8137},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.19386},\n\tdoi = {10.1111/nph.19386},\n\tabstract = {Targeted removal experiments are a powerful tool to assess the effects of plant species or (functional) groups on ecosystem functions. However, removing plant biomass in itself can bias the observed responses. This bias is commonly addressed by waiting until ecosystem recovery, but this is inherently based on unverified proxies or anecdotal evidence. Statistical control methods are efficient, but restricted in scope by underlying assumptions. We propose accounting for such biases within the experimental design, using a gradient of biomass removal controls. We demonstrate the relevance of this design by presenting (1) conceptual examples of suspected biases and (2) how to observe and control for these biases. Using data from a mycorrhizal association-based removal experiment, we show that ignoring biomass removal biases (including by assuming ecosystem recovery) can lead to incorrect, or even contrary conclusions (e.g. false positive and false negative). Our gradient design can prevent such incorrect interpretations, regardless of whether aboveground biomass has fully recovered. Our approach provides more objective and quantitative insights, independently assessed for each variable, than using a proxy to assume ecosystem recovery. Our approach circumvents the strict statistical assumptions of, for example, ANCOVA and thus offers greater flexibility in data analysis.},\n\tlanguage = {en},\n\tnumber = {n/a},\n\turldate = {2024-03-26},\n\tjournal = {New Phytologist},\n\tauthor = {Monteux, Sylvain and Blume-Werry, Gesche and Gavazov, Konstantin and Kirchhoff, Leah and Krab, Eveline J. and Lett, Signe and Pedersen, Emily P. and Väisänen, Maria},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/nph.19386},\n\tkeywords = {Monte Carlo simulations, biomass removal gradient, disturbance bias, ectomycorrhizal plant, ericoid mycorrhizal plant, plant removal experiment, shrubification},\n\tpages = {19386},\n}\n\n\n\n\n\n Targeted removal experiments are a powerful tool to assess the effects of plant species or (functional) groups on ecosystem functions. However, removing plant biomass in itself can bias the observed responses. This bias is commonly addressed by waiting until ecosystem recovery, but this is inherently based on unverified proxies or anecdotal evidence. Statistical control methods are efficient, but restricted in scope by underlying assumptions. We propose accounting for such biases within the experimental design, using a gradient of biomass removal controls. We demonstrate the relevance of this design by presenting (1) conceptual examples of suspected biases and (2) how to observe and control for these biases. Using data from a mycorrhizal association-based removal experiment, we show that ignoring biomass removal biases (including by assuming ecosystem recovery) can lead to incorrect, or even contrary conclusions (e.g. false positive and false negative). Our gradient design can prevent such incorrect interpretations, regardless of whether aboveground biomass has fully recovered. Our approach provides more objective and quantitative insights, independently assessed for each variable, than using a proxy to assume ecosystem recovery. Our approach circumvents the strict statistical assumptions of, for example, ANCOVA and thus offers greater flexibility in data analysis.\n
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