Fig. 4: The influence of nonlinear thermal response of soil microbial carbon usage efficiency (CUE) on the decay constant and soil organic carbon (SOC) simulated at transient conditions.

The decay constant (effective K, 1/yr) (a) used to quantify SOC mass loss (b) in response to air mean annual temperature (MAT) emerging from model simulations by microbial-explicit versus first-order models at transient conditions (i.e., 1 year) by including the segmented equations of original CUE as a function of air MAT fitted using segmented regressions (see Supplementary Fig. 4 legend for the segmented equations) (see Methods for modeling details). The relative changes (%) of both variables (effective K and SOC) as compared with equilibrium values at 20 °C were presented to facilitate comparisons between models.