Fig. 5

(a) Spearman correlation analysis of core genera (the top 10 abundance) and aboveground biomass, nitrogen content and root tropane alkaloids content of Anisodus tanguticus. The numbers in the graph indicate the R-value. The colors in the graph indicate the P-value. The red and blue indicate positive and negative correlations, and the color depth indicates strong correlation (* P < 0.05, ** P < 0.01, *** P < 0.01). (b) The predictions of core genera to aboveground biomass, nitrogen content and root anisodine content based on random forest regression analysis. “% var explained” means the proportion of variance explained. Asterisks indicate the factor that has a significant effect. The significance levels are as follows: P < 0.05, one asterisk (*); P < 0.01, two asterisks (**); P < 0.001, three asterisks (***)