Fig. 1: A negative association between beta diversity and alpha diversity of arbuscular mycorrhizal fungi (AMF) community along a nitrogen addition gradient.

a The occurrences of 116 AMF operational taxonomic units (OTUs) across 70 samples (n = 70) showed changes of AMF community structure under nitrogen addition. Pink-filled squares denote the presence (1) of an AMF OTU in a sampling plot, while white squares indicate the absence (0). b Nitrogen addition significantly decreased AMF α-diversity as measured by OTU richness (n = 70). Note AMF Shannon’s diversity also decreased with nitrogen addition as showed in the Supplementary Fig. S5. c–h Nitrogen addition significantly increased AMF β-diversity (n = 70). The c Jaccard dissimilarity-, d Bray–Curtis dissimilarity-, and e Sørensen dissimilarity-based principal coordinates (PCo) analysis followed by permutational analysis of variance (adonis2) and beta dispersion showed significant effects of nitrogen addition on AMF community composition, and on AMF community beta diversity as measured by an increase in the distance to centroid among replications of a nitrogen level. Fitting curve showing the significant increase of AMF β-diversity (distance-to-centroid) measured based on f Jaccard, g Bray–Curtis, and h Sørensen dissimilarity with increasing level of nitrogen addition. AMF α-diversity correlates negatively with β-diversity (distance-to-centroid) measured based on i Jaccard, j Bray–Curtis, and k Sørensen dissimilarity along a nitrogen addition gradient (n = 70).