Fig. 5. Fungal community structure assessed by β-diversity patterns using the principal coordinate analysis plots of Bray‒Curtis distances. Different shapes represent grazing exclusion or grazing soils, and colors represent grassland types. E,exclusion; G,grazing; TD, temperate desert; TS, temperate steppe; MM, mountain meadow. ANOSIM similarity analysis was used to test the significance between groups.
3.5 Correlations of grazing exclusion and grassland types with plant, soil and fungal composition and diversity
In the 0-5 cm soil layer (Fig. a,c), all soil indices except the C:N soil index were significantly correlated with the grazing exclusion treatment, additionally, plant coverage was significantly correlated with the no-grazing treatment, but fungal α-diversity was not significantly correlated with the no-grazing treatment. Except for the plant Pielou index and fungal Chao1 index, all other plant, soil and fungal diversity indicators were significantly or highly significantly correlated with grassland type. In addition, we found that soil SOC, KN, TP, C:P, N:P and BD were significantly or highly significantly negatively correlated with the fungal Shannon index and Simpson index. In terms of fungal composition, Eurotiomycetes was significantly and positively correlated with the plant Pielou index, KN, TP, N:P, and pH, and Dothideomycetes was significantly and negatively correlated with the SOC but significantly and positively correlated with pH. We found that soil KN, TP and N:P were significantly or highly significantly correlated with Dothideomycetes ,Archaeorhizomycetes , Agaricomycetes andGlomeromycetes .
In the 5-10 cm soil layer (Figs. b,d), plant cover was significantly correlated with grazing closure treatments, and all plant, soil, and fungal diversity indices, except for the plant Pielou index, fungal Shannon index, fungal Chao1 index, and BD, were significantly or highly significantly correlated with grassland type. In addition, we found that soil C:N was significantly and positively correlated with the fungal Shannon index and Simpson index, and soil C:P was significantly and positively correlated with the fungal Chao1 index. In terms of fungal composition, only Rhizophlyctidomycetes was significantly negatively correlated with the plant Simpson’s index and highly significantly negatively correlated with the plant Pielou’s index.