Fig. 3. The relative importance of environmental variables in influencing the response of soil organic carbon (SOC) to warming.

a, b the results for SOC stock and content, respectively. The relative importance is identified by a meta-forest model driven by the listed variables to predict the response of SOC stock and content to warming. MAP, mean annual precipitation; MAT, mean annual temperature; PCI, precipitation concentration index; P in summer, the fraction of precipitation in summer to MAP; NPP, net primary production. Insets show the performance of the meta-forest model with RMSE and R² show the rooted mean squared error and determination coefficients, respectively. Brown bars, soil-related variables; blue bars, climate-related variables; grey bars, topography-related variables; green bars, vegetation-related variables.