Responses of Soil Microbial Communities and Functions in an Alpine Grassland of the Qinghai Lake Basin With Grazing Disturbance

Soil ecosystems host diverse microbial communities, which are influenced by various environmental factors, soil properties, vegetation characteristics, and anthropogenic activities, such as livestock grazing. Grazing serves as a critical management practice in the alpine grasslands of the Qinghai-Tibet Plateau, affecting soil microbial communities and their functions through processes such as forage consumption, trampling, and the deposition of feces and urine. In this study, we utilized the scientific and technological platform "Alpine Grassland-Livestock Adaptive Management Technology Platform" in Qinghai Province to examine the effects of grazing intensity on soil microbial communities and functions. Experimental treatments included different grazing intensities (light grazing, moderate grazing, and heavy grazing), along with a no-grazing control. Metagenomic sequencing technology was employed to investigate the impact of these grazing intensities on the microbial community composition and functional attributes in alpine grasslands. The results indicated that: (1) Actinobacteria, Proteobacteria, and Chloroflexi were the dominant bacterial communities in the soil, while Ascomycota, Mucoromycota, and Basidiomycota represented the primary fungal communities. (2) Grazing had a greater impact on soil fungal communities than on bacterial communities, altering the Shannon diversity index and Simpson index of soil fungal communities. (3) Soil pH and soil moisture were important factors influencing changes in soil microbial communities. (4) Functional analysis focusing on the "nitrogen metabolism" pathway indicated that under light grazing conditions, the relative abundance of multiple functional genes, particularly those involved in denitrification, decreased.