Fig. 5

The contributions of environmental factors to bacterial (a) and fungal (b) richness were determined using a correlation analysis and random forest modeling. The circle sizes represent the variables’ importances, which were calculated as percentages of the increase in mean square error using a random forest model. The correlations among microbial communities were also evaluated. The Mantel test was used to determine the correlations between physicochemical properties and the bacterial and fungal communities (c). The following significance levels were used in this analysis: *P < 0.05, **P < 0.01, ***P < 0.001 sucrase activities (SA), urease activity (UA), catalase activity (CA), acid phosphatase activity (ACA), and alkaline phosphatase activity (ALA).