Dynamics of Soil Organic Carbon Under Uncertain Climate Change and Elevated Atmospheric CO2

Abstract

Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon (SOC). SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998–2100 were simulated using stochastic modelling. Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration. Therefore, there was a counteract effect on SOC dynamics between climate warming and elevated CO2. For different soil erosion extents, warming 1 C and elevated atmospheric CO2 resulted in SOC increase at least 15%, while warming 5 C and elevated CO2 resulted in SOC decrease more than 29%. SOC predictions with uncertainty assessment were conducted for different scenarios of soil erosion, climate change, and elevated CO2. Statistically, SOC decreased linearly with the probability. SOC also decreased with time and the degree of soil erosion. For example, in 2100 with a probability of 50%, SOC was 1617, 1167, and 892 g m−2, respectively, for no, minimum, and maximum soil erosion. Under climate warming 5 C and elevated CO2, the soil carbon pools became a carbon source to the atmosphere (P > 95%). The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2.