Expansion of Invasive Species on Ombrotrophic Bogs: Desiccation or High N Deposition?. Tomassen, H. B. M.; Smolders, A. J. P.; Limpens, J.; Lamers, L. P. M.; and Roelofs, J. G. M. 41(1):139–150.
Expansion of Invasive Species on Ombrotrophic Bogs: Desiccation or High N Deposition? [link]Paper  doi  abstract   bibtex   
In many ombrotrophic bog areas the invasion of grass (e.g. Molinia caerulea) and tree (e.g. Betula pubescens) species has become a major problem. We investigated whether the invasion of such species is due to high atmospheric nitrogen (N) deposition by conducting a fertilization experiment. The effects of experimentally increased N input on Molinia, Betula and Eriophorum vaginatum were studied in desiccated bog vegetation in Ireland, where there is relatively low background N deposition. Four different N treatments were applied for 3 years: 0 (control), 2, 4 and 8~g m22122~year22121. Ammonium and nitrate concentrations in the peat moisture increased at high N addition rates, leading to significantly higher carbon~:~nitrogen (C~:~N) and nitrogen~: phosphorus (N~:~P) ratios in the top layer of the peat. The potential CO2 production rate of the peat was not stimulated at high N addition rates due to severe acidification of the peat. Despite high tissue N~:~P ratios (above 40), above-ground biomass production by Molinia was stimulated at high N addition rates, and foliar nutrient concentrations were unaffected. In contrast to Molinia, Betula and Eriophorum were unable to increase their above-ground biomass, probably due to P limitation. Regrowth of the lichen Cladonia portentosa was suppressed at high N addition rates. Synthesis and applications. We conclude that the invasion of bogs by Molinia and Betula is likely to be less affected by desiccation than by increased N availability. Apparently, Molinia is well adapted to P-limiting conditions, which may explain its success in regions with increased N deposition levels. The high availability of P in many Dutch bogs compared with Irish bogs, together with prolonged high N deposition levels, may explain the strong increase in both Molinia and Betula observed in the Netherlands. As long as N and P availabilities in Dutch bogs are too high to prevent invasion of Betula and/or Molinia, management measures stimulating growth of Sphagnum mosses could probably reduce the negative effects of high N deposition levels. Journal of Applied Ecology (2004) 41, 1392013150
@article{tomassenExpansionInvasiveSpecies2004,
  title = {Expansion of Invasive Species on Ombrotrophic Bogs: Desiccation or High {{N}} Deposition?},
  author = {Tomassen, Hilde B. M. and Smolders, Alfons J. P. and Limpens, Juul and Lamers, Leon P. M. and Roelofs, Jan G. M.},
  date = {2004-02},
  journaltitle = {Journal of Applied Ecology},
  volume = {41},
  pages = {139--150},
  issn = {0021-8901},
  doi = {10.1111/j.1365-2664.2004.00870.x},
  url = {https://doi.org/10.1111/j.1365-2664.2004.00870.x},
  abstract = {In many ombrotrophic bog areas the invasion of grass (e.g. Molinia caerulea) and tree (e.g. Betula pubescens) species has become a major problem. We investigated whether the invasion of such species is due to high atmospheric nitrogen (N) deposition by conducting a fertilization experiment. The effects of experimentally increased N input on Molinia, Betula and Eriophorum vaginatum were studied in desiccated bog vegetation in Ireland, where there is relatively low background N deposition. Four different N treatments were applied for 3 years: 0 (control), 2, 4 and 8~g m22122~year22121. Ammonium and nitrate concentrations in the peat moisture increased at high N addition rates, leading to significantly higher carbon~:~nitrogen (C~:~N) and nitrogen~: phosphorus (N~:~P) ratios in the top layer of the peat. The potential CO2 production rate of the peat was not stimulated at high N addition rates due to severe acidification of the peat. Despite high tissue N~:~P ratios (above 40), above-ground biomass production by Molinia was stimulated at high N addition rates, and foliar nutrient concentrations were unaffected. In contrast to Molinia, Betula and Eriophorum were unable to increase their above-ground biomass, probably due to P limitation. Regrowth of the lichen Cladonia portentosa was suppressed at high N addition rates. Synthesis and applications. We conclude that the invasion of bogs by Molinia and Betula is likely to be less affected by desiccation than by increased N availability. Apparently, Molinia is well adapted to P-limiting conditions, which may explain its success in regions with increased N deposition levels. The high availability of P in many Dutch bogs compared with Irish bogs, together with prolonged high N deposition levels, may explain the strong increase in both Molinia and Betula observed in the Netherlands. As long as N and P availabilities in Dutch bogs are too high to prevent invasion of Betula and/or Molinia, management measures stimulating growth of Sphagnum mosses could probably reduce the negative effects of high N deposition levels. Journal of Applied Ecology (2004) 41, 1392013150},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-7209014,betula-pubescens,bogs,ecology,ecosystem-invasibility,forest-resources,invasive-species,molinia-caerulea,netherlands,nitrogen,ombrotrophic,wetlands},
  number = {1}
}
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