Fig. 4. Microbial CUE as the primary regulator of global SOC storage.

a, Spatially explicit model components obtained through the PRODA approach with the microbial model were substituted by their spatially invariant counterparts to assess their influence on SOC stocks (that is, the sum of absolute deviations from PRODA estimates over the globe) and distributions (that is, deviation of explained variation in observations defined by equation (2)). b, We further proportionally changed the retrieved parameter values of different components and found that global SOC stock is most sensitive to changes of CUE. Error bars and shaded areas show the 2σ confidence interval in the 200-time bootstrapping. It is noted that the axes in a are scaled by a signed square-root function.