2.7 Statistical analysis
One-way ANOVA and Duncan’s multiple tests (P < 0.05) were performed using IBM SPSS Statistics 26 (IBM Corporation, New York) software to compare the means of plant, AM fungi, and soil physicochemical property data. \soutTwo-way ANOVA was used to analysis the interaction effect between N addition and soil agglomerate particle size on GRSP. The correlation between soil physicochemical properties and herbaceous plants diversity was calculated by Pearson’s test (two-tailed) at two significant levels, P < 0.05 andP < 0.01. RDA analysis was used to reveal the effect of soil properties on the community composition of AM fungi. Structural equation modeling (SEM) was used to predict causal pathways of N addition, key soil physicochemical indicators, and AM fungi on herbaceous plant diversity. Build prior models and evaluate model fit using chi-square, RMSEA, and GFI.