Fig. 5: Random Forest models of different ecosystems and climatic zones.

a Subtropical grassland. b Temperate grassland. c Subtropical forest. d Temperate forest. Random Forest models showing the average predictive importance (mean square error (MSE) increase percentage) of each environmental factor in the absolute content of soil amino sugars (characterization of microbial residues). Asterisks indicate the significance of each predictor, with one and two asterisks indicating p < 0.05 and p < 0.01, respectively.