Abstract
In this paper, we attempt to analyse the respective influences of land-use and climate changes on the global and regional balances of soil organic carbon (SOC) stocks. Two time periods are analysed: the historical period 1901-2000 and the period 2000-2100. The historical period is analysed using a synthesis of published data as well as new global and regional model simulations, and the future is analysed using models only. Historical land cover changes have resulted globally in SOC release into the atmosphere. This human induced SOC decrease was nearly balanced by the net SOC increase due to higher CO2 and rainfall. Mechanization of agriculture after the 1950s has accelerated SOC losses in croplands, whereas development of carbon-sequestering practices over the past decades may have limited SOC loss from arable soils. In some regions (Europe, China and USA), croplands are currently estimated to be either a small C sink or a small source, but not a large source of CO2 to the atmosphere.
In the future, according to terrestrial biosphere and climate models projections, both climate and land cover changes might cause a net SOC loss, particularly in tropical regions. The timing, magnitude, and regional distribution of future SOC changes are all highly uncertain. Reducing this uncertainty requires improving future anthropogenic CO2 emissions and land-use scenarios and better understanding of biogeochemical processes that control SOC turnover, for both managed and un-managed ecosystems.
Original language | English |
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Pages (from-to) | 700-718 |
Number of pages | 19 |
Journal | Tellus B |
Volume | 62 |
Issue number | 5 |
Early online date | 20 Jul 2010 |
DOIs | |
Publication status | Published - Nov 2010 |
Keywords
- C-13 natural-abundance
- net primary production
- organic-matter
- atmospheric CO2
- temperature sensitivity
- agricultural soils
- permafrost carbon
- European forests
- terrestrial biosphere
- cycle feedbacks