Abstract: To clarify the effects of spring grazing exclusion on vegetation characteristics, soil physical and chemical properties and soil fungal community characteristics of moderately degraded alpine meadow, two treatments of spring grazing exclusion and free grazing were set up in an alpine meadow of Qilian Mountains. Plant community were investigated and soil samples were collected during the season with peak plant growth after the ending of grazing exclusion. The results showed that grazing exclusion significantly increased plant community diversity index, evenness index and richness index by 80.00%, 50.94%, and 21.89% respectively (P<0.05). Grazing exclusion significantly increased plant biomass by 52.41% (P<0.05). After grazing exclusion, the ratio of aboveground to belowground biomass increased from 8.58% to 25.59%, indicating that the distribution pattern of plant biomass was changed. Grazing exclusion significantly increased the contents of soil organic carbon and total potassium by 10.64% and 1.10% (P<0.05), respectively, while decreased soil bulk density and pH by 17.83% and 4.60% (P<0.05), respectively. The relative abundance of Ascomycetes in soil increased while that of Mortierella decreased under grazing exclusion treatment. There was no significant difference in soil fungal community diversity index between the two treatments. The results of PCoA analysis showed that the interpretation rates of primary coordinates 1 (PCo1), primary coordinate 2 (PCo2), and principal coordinate 3 (PCo3) on the differences in fungal community structure were 17.58%, 12.07%, and 11.51%, respectively, with a cumulative interpretation rate of 41.16%. The modular analysis of fungal co-occurrence network showed that the complexity of soil fungal network was higher and soil fungal community was more stable under the treatment of grazing exclusion. The analysis of variance of vegetation and soil factors showed that soil water content and belowground biomass were the two main factors regulating the assembly of fungal community.

Key words: spring grazing exclusion, alpine meadow, plant community, soil physicochemical property, soil fungal community