How will organic carbon stocks in mineral soils evolve under future climate? Global projections using RothC for a range of climate change scenarios

[摘要] We use a soil carbon (C) model (RothC), driven by a range of climate modelsfor a range of climate scenarios to examine the impacts of future climate onglobal soil organic carbon (SOC) stocks. The results suggest an overallglobal increase in SOC stocks by 2100 under all scenarios, but with adifferent extent of increase among the climate model and emissionsscenarios. The impacts of projected land use changes are also simulated, buthave relatively minor impacts at the global scale. Whether soils gain orlose SOC depends upon the balance between C inputs and decomposition.Changes in net primary production (NPP) change C inputs to the soil, whilstdecomposition usually increases under warmer temperatures, but can also beslowed by decreased soil moisture. Underlying the global trend of increasingSOC under future climate is a complex pattern of regional SOC change. SOClosses are projected to occur in northern latitudes where higher SOCdecomposition rates due to higher temperatures are not balanced by increasedNPP, whereas in tropical regions, NPP increases override losses due tohigher SOC decomposition. The spatial heterogeneity in the response of SOCto changing climate shows how delicately balanced the competing gain andloss processes are, with subtle changes in temperature, moisture, soil typeand land use, interacting to determine whether SOC increases or decreases inthe future. Our results suggest that we should stop looking for a singleanswer regarding whether SOC stocks will increase or decrease under futureclimate, since there is no single answer. Instead, we should focus onimproving our prediction of the factors that determine the size anddirection of change, and the land management practices that can beimplemented to protect and enhance SOC stocks.

[学科分类] 地球化学与岩石