Soil Carbon Stocks under Present and Future Climate with Specific Reference to European Ecoregions. Lal, R. 81(2):113–127.
Soil Carbon Stocks under Present and Future Climate with Specific Reference to European Ecoregions [link]Paper  doi  abstract   bibtex   
World soils and terrestrial ecosystems have been a source of atmospheric abundance of CO2 ever since settled agriculture began about 10-13~millennia ago. The amount of CO2-C emitted into the atmosphere is estimated at 136~±~55~Pg from terrestrial ecosystems, of which emission from world soils is estimated at 78~±~12~Pg. Conversion of natural to agricultural ecosystems decreases soil organic carbon (SOC) pool by 30-50\,% over 50-100~years in temperate regions, and 50-75\,% over 20-50~years in tropical climates. The projected global warming, with estimated increase in mean annual temperature of 4-6°C by 2100, may have a profound impact on the total soil C pool and its dynamics. The SOC pool may increase due to increase in biomass production and accretion into the soil due to the so-called ” CO2 fertilization effect”, which may also enhance production of the root biomass. Increase in weathering of silicates due to increase in temperature, and that of the formation of secondary carbonates due to increase in partial pressure of CO2 in soil air may also increase the total C pool. In contrast, however, SOC pool may decrease because of: (i) increase in rate of respiration and mineralization, (ii) increase in losses by soil erosion, and (iii) decrease in protective effects of stable aggregates which encapsulate organic matter. Furthermore, the relative increase in temperature projected to be more in arctic and boreal regions, will render Cryosols under permafrost from a net sink to a net source of CO2 if and when permafrost thaws. Thus, SOC pool of world soils may decrease with increase in mean global temperature. In contrast, the biotic pool may increase primarily because of the CO2 fertilization effect. The magnitude of CO2 fertilization effect may be constrained by lack of essential nutrients (e.g., N, P) and water. The potential of SOC sequestration in agricultural soils of Europe is 70-190~Tg~C~yr-1. This potential is realizable through adoption of recommended land use and management, and restoration of degraded soils and ecosystems including wetlands. [Excerpt: Importance of forests] Forests play an important role in the C cycle both at regional and global scales. Distribution of the forested area in Europe is shown in Table 5. Combined with the former USSR, total area under forest in Europe is 904.3 Mha or 59\,% of the total forest in the Northern Hemisphere temperate and boreal zones. Review of the C budget studies in European forests show that forest area of Europe of 149 Mha (excluding the FSU) yields a whole tree C sink of 101.3 Tg C yr-1 which is equivalent to 9.5\,% of the European emissions. The total C stock of these forests (whole tree) has been estimated at 7.9 Pg C, and a wood C sink of 29.2 Tg C yr-1 (Nabuurs et al. 1997). In comparison, the annual sink capacity of FSU forest has been estimated at 517 Tg C yr-1 by Kolchugina and Vinson (1993a, b) and 740 Tg C yr-1 by Dixon et al. (1994). Janssens et al. (2003) estimated the net biome productivity of the European forest sector, with a total area of 384 Mha, at 377 Tg C yr-1. The sink capacity of all temperate forests has been estimated at 1.4 Pg C yr-1 by Sedjo (1992), and for northern boreal and temperate zone forest at 0.7- 1.3 Pg C yr-1 by Sampson et al. (1993). [] Despite its importance, a few studies have accounted for the C sink capacity of soils supporting forests. In this regard, a preliminary estimate provided by Nabuurs et al. (1997) is extremely relevant. They reported the total SOC pool of soils supporting European forests at 12.0 Pg, but did not provide an estimate of the rate of SOC sequestration. [] Liski et al. (2002) estimated C budget of soils and trees in the forests of 14 EU countries plus Norway and Switzerland from 1950 to 2040. The SOC pool increased throughout the study period. The SOC sink was 26 Tg C yr-1 in 1990 and projected to be 43 Tg C yr-1 by 2040. The SOC sink in forest soil can be managed by choice of species, soil fertility, etc. Positive impact of CO2 fertilization on C sequestration in the forest biomass and soils may be limited by lack of nutrients or soil fertility constraints (Oren et al. 2001). [...]
@article{lalSoilCarbonStocks2008,
  title = {Soil Carbon Stocks under Present and Future Climate with Specific Reference to {{European}} Ecoregions},
  author = {Lal, Rattan},
  date = {2008-06},
  journaltitle = {Nutrient Cycling in Agroecosystems},
  volume = {81},
  pages = {113--127},
  issn = {1573-0867},
  doi = {10.1007/s10705-007-9147-x},
  url = {https://doi.org/10.1007/s10705-007-9147-x},
  abstract = {World soils and terrestrial ecosystems have been a source of atmospheric abundance of CO2 ever since settled agriculture began about 10-13~millennia ago. The amount of CO2-C emitted into the atmosphere is estimated at 136~±~55~Pg from terrestrial ecosystems, of which emission from world soils is estimated at 78~±~12~Pg. Conversion of natural to agricultural ecosystems decreases soil organic carbon (SOC) pool by 30-50\,\% over 50-100~years in temperate regions, and 50-75\,\% over 20-50~years in tropical climates. The projected global warming, with estimated increase in mean annual temperature of 4-6°C by 2100, may have a profound impact on the total soil C pool and its dynamics. The SOC pool may increase due to increase in biomass production and accretion into the soil due to the so-called ” CO2 fertilization effect”, which may also enhance production of the root biomass. Increase in weathering of silicates due to increase in temperature, and that of the formation of secondary carbonates due to increase in partial pressure of CO2 in soil air may also increase the total C pool. In contrast, however, SOC pool may decrease because of: (i) increase in rate of respiration and mineralization, (ii) increase in losses by soil erosion, and (iii) decrease in protective effects of stable aggregates which encapsulate organic matter. Furthermore, the relative increase in temperature projected to be more in arctic and boreal regions, will render Cryosols under permafrost from a net sink to a net source of CO2 if and when permafrost thaws. Thus, SOC pool of world soils may decrease with increase in mean global temperature. In contrast, the biotic pool may increase primarily because of the CO2 fertilization effect. The magnitude of CO2 fertilization effect may be constrained by lack of essential nutrients (e.g., N, P) and water. The potential of SOC sequestration in agricultural soils of Europe is 70-190~Tg~C~yr-1. This potential is realizable through adoption of recommended land use and management, and restoration of degraded soils and ecosystems including wetlands.

[Excerpt: Importance of forests] Forests play an important role in the C cycle both at regional and global scales. Distribution of the forested area in Europe is shown in Table 5. Combined with the former USSR, total area under forest in Europe is 904.3 Mha or 59\,\% of the total forest in the Northern Hemisphere temperate and boreal zones. Review of the C budget studies in European forests show that forest area of Europe of 149 Mha (excluding the FSU) yields a whole tree C sink of 101.3 Tg C yr-1 which is equivalent to 9.5\,\% of the European emissions. The total C stock of these forests (whole tree) has been estimated at 7.9 Pg C, and a wood C sink of 29.2 Tg C yr-1 (Nabuurs et al. 1997). In comparison, the annual sink capacity of FSU forest has been estimated at 517 Tg C yr-1 by Kolchugina and Vinson (1993a, b) and 740 Tg C yr-1 by Dixon et al. (1994). Janssens et al. (2003) estimated the net biome productivity of the European forest sector, with a total area of 384 Mha, at 377 Tg C yr-1. The sink capacity of all temperate forests has been estimated at 1.4 Pg C yr-1 by Sedjo (1992), and for northern boreal and temperate zone forest at 0.7- 1.3 Pg C yr-1 by Sampson et al. (1993).

[] Despite its importance, a few studies have accounted for the C sink capacity of soils supporting forests. In this regard, a preliminary estimate provided by Nabuurs et al. (1997) is extremely relevant. They reported the total SOC pool of soils supporting European forests at 12.0 Pg, but did not provide an estimate of the rate of SOC sequestration.

[] Liski et al. (2002) estimated C budget of soils and trees in the forests of 14 EU countries plus Norway and Switzerland from 1950 to 2040. The SOC pool increased throughout the study period. The SOC sink was 26 Tg C yr-1 in 1990 and projected to be 43 Tg C yr-1 by 2040. The SOC sink in forest soil can be managed by choice of species, soil fertility, etc. Positive impact of CO2 fertilization on C sequestration in the forest biomass and soils may be limited by lack of nutrients or soil fertility constraints (Oren et al. 2001). [...]},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-4942860,carbon-stock,climate-change,degradation,europe,forest-resources,protection,soil-erosion,soil-resources,wind},
  number = {2}
}

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