Fig. 1: Geographic locations of soil sampling sites and comparison of soil organic matter (SOM) decomposition kinetics parameters.

a Global distribution of sampling sites. b, c Reference decomposition rates (k1ref, k2ref, and k3ref) for the fast, slow, and passive SOM pool in the two-pool model (M2) and the three-pool model (M3), respectively. d, e Relative sizes (f1, f2, and f3) for the fast, slow, and passive SOM pool in the two- and three-pool model, respectively. In b–e the band reflects the probability density distribution of parameter values, the box represents the first and third quantile, the horizontal line in the box represents the median value, the vertical lines represent minimum and maximum values, the solid dots represent outliers, and the numbers shown in each panel represent sample sizes. The four models are ANIMO46, DAISY47, CLMcn13, and DAYCENT48.