Fig. 2. Venn diagram of fungal communities in different
grassland types based on OTU abundance. Different colors represent
grassland types. The letter G denotes grazing, and the letter E denotes
grazing exclusion.
3.3. Soil fungal community composition as affected by grazing exclusion
and grassland type
At the phylum level (Fig. 3A), Ascomycota and Basidiomycota were the
dominant fungi in the three grassland types in the 0-5 cm soil layer
before exclusion. After exclusion, Ascomycota decreased by 14.72% and
9.74% in temperate deserts and mountain meadows respectively, and
increased by 4.82% in temperate steppes. Basidiomycota increased by
238.8% and 47.68% in temperate deserts and mountain meadows
respectively, but decreased by 23.12% in temperate steppes. In the 5-10
cm soil layer (Fig. 3B), the main fungi of the three grassland types
were the same as those in the 0-5 cm soil layer. It is worth mentioning
the changes in Mortierellomycota , which we found to be
significantly lower after grazing exclusion in the 0-5 soil layer in
mountain meadows (P < 0.05), and highly significant higher in
the 5-10 soil layer in temperate deserts(P < 0.001). At the
class level in the 0-5 cm soil layer (Fig. 3C), Regardless of grazing or
grazing exclusion, Dothideomycetes, Archaeorhizomycetes, Sordariomycetes
and Agaricomycetes were dominant in three grassland types studied, while
in the temperate desert Archaeorhizomycetes almost disappeared. This
result illustrates the different responses of fungi to environmental
changes. In the 5-10 cm soil layer (Fig. 3D), Sordariomycetesincreased significantly by 279.32% in the temperate desert before
exclusion compared to the 0-5 cm soil layer. Grassland type had a highly
significant effect on Ustilaginomycetes (P <
0.001) and a significant effect on Eurotiomycetes andOrbiliomycetes (P < 0.05). In addition,
grassland type had a highly significant effect on Dothideomycetesand Archaeorhizomycetes in both the 0-5 cm and the 5-10 cm soil
layers (P < 0.001) (Supplementary Tables 6 and 7).