Grazing is one of the main ways to utilize grassland. A reasonable grazing method can achieve sustainable utilization of grassland. However， most studies focus on grazing of a single livestock species or fixed-proportion mixed grazing， lacking exploration of the impact of different proportion mixed grazing on grassland ecosystem. This study investigated the effects of different herbivore assemblage grazing on soil nutrients and enzyme activities based on the alpine grasslands of the Qinghai-Tibet Plateau. The experiment was established including a control （CK）， yak-only grazing （YG）， Tibetan sheep-only grazing （SG）， and mixed grazing of yaks and Tibetan sheep （MG1∶2， MG1∶4， MG1∶6）. Plant and soil samples were collected from the experimental plots from the 6th to the 8th year of grazing to analyze changes in grassland plant biomass， soil total nutrients （total carbon， total nitrogen， total phosphorus）， and the activities of enzymes related to carbon and nitrogen cycles （nitrate reductase， nitrite reductase， urease， hydroxylamine reductase， amylase， and neutral protease）. The results showed that both grazing patterns and experimental year had significant interactive effects on the activities of carbon- and nitrogen cycle-related soil enzymes. Soil nutrients and enzyme activities exhibited significant interannual dynamic characteristics. Mixed grazing had distinct effects on soil nutrients and enzyme activity compared to single-species grazing. As the grazing duration increases， the mixed grazing system with a yak-to-Tibetan sheep ratio of 1∶2 or 1∶4 gradually restores the soil nutrients and enzyme activity of alpine grasslands to levels closer to those of natural grasslands. The results suggest that grazing with different livestock combinations is more conducive to maintaining the stability of grassland ecosystem functions.

Herbivore assemblage grazing  /  Soil ecological stoichiometry  /  Grazing management  /  Soil enzyme activity