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- Title
Effects of model assumptions for soil processes on carbon turnover in the earth system.
- Authors
Foereid, B.; Ward, D. S.; Mahowald, N.; Paterson, E.; Lehmann, J.
- Abstract
Soil organic matter (SOM) is the largest store of organic carbon (C) in the biosphere, but still the turnover of SOM is incompletely understood and not well described in global C cycle models. Here we use the Community Land Model (CLM) and compare the out- put for soil organic C (SOC) to estimates from a global data set. We also modify the assumptions about SOM turnover in two ways: (1) we assume distinct temperature sensitivities of SOC pools with different turnover time and (2) we assume a priming effect, such that decomposition rate of native SOM increases in response to a supply of fresh organic matter. The standard model predicted the global distribution of SOM reasonably well in most areas, but it failed to predict the very high stocks of SOM at high latitudes. It also predicted somewhat too much SOC in areas with high plant productivity, such as tropical rain forests and some mid-latitude areas. Assuming that the temperature sensitivity of SOC decomposition is dependent on the turnover rate of component pools reduced total SOC at equilibrium by a relatively small amount (<1% globally). Including a priming effect reduced total global SOC more (6.6% globally) and tended to decrease SOC most in areas with high plant input (tropical and temperate forests), which were also the areas where the unmodified model overpredicted SOC (by about 40 %). The model was then run with climate change prediction for the standard and modified versions. Future simulations showed that differences between the standard and modified versions were maintained in a future with climate change (4-6 and 23-47 Pg difference in soil carbon between standard simulation and the modified with temperature sensitivity and priming respectively).
- Subjects
CARBON in soils; HUMUS; ORGANIC compounds; BIOSPHERE; PLANT productivity; GLOBAL temperature changes
- Publication
Earth System Dynamics Discussions, 2013, Vol 4, Issue 2, p1091
- ISSN
2190-4995
- Publication type
Article
- DOI
10.5194/esdd-4-1091-2013