Fig. 3: Relative importance of factors mediating biodiversity and SOC responses under N enrichment.
Relative importance of each factor in predicting the response of plant richness (a), soil bacterial richness (b), fungal richness (c), and SOC (d) under N enrichment, based on the entire dataset (n = 2141). Variable importance represents the increase in mean error (computed on out-of-bag data) across trees when a predictor is permuted. Box boundaries represent the 75th and 25th percentiles, and whisker caps represent the 95th and 5th percentiles. Predictors shown in black are significant, whereas those in gray are non-significant (α = 0.05). MAT mean annual temperature, TN total N, SM soil moisture, NH4+-N ammonia nitrogen, NO3−-N nitrate nitrogen. The relationships between environmental factors (e.g., climatic variables and soil responses) and plant, soil microbial communities and SOC are shown in Supplementary Figs. 3–5. e Relationships between diversity (plant, soil bacterial, and fungal communities) and SOC under ambient conditions, evaluated using two-sided t-tests in mixed-effect models with study ID as a random factor. Values are mean effect size ± standard deviation (SD). f Associations between the responses of diversity (plant, soil bacterial and fungal communities) and SOC under N enrichment, evaluated using two-sided t-tests in mixed-effect meta-regression models, including study ID and N rate level as random factors to account for variability across studies and the N-induced potential co-variation. Values are mean effect size ± 95% confidence intervals (CIs). Numbers in parentheses below each P value in e, f indicate the number of observations. Created in BioRender. Jiao, S. (2025) https://BioRender.com/814s45u. Source data are provided as a Source data file.
