关键词: 放牧, 高寒草原, 植被地上生物量, 微生物群落结构多样性, 土壤养分

Abstract: Based on the genomic amplification technology,the effects of six mixingpatterns of yak and Tibetan sheep grazing on the structure of soil microbial community were analyzed,and the differences in vegetation,soil and soil microorganism under the same grazing intensity and different grazing modes were analyzed in combination with the physical and chemical indexes of vegetation and soil. The results showed that grazing significantly reduced the aboveground biomass of vegetation,in which legume biomass decreased by 90.9%,and there was no difference in aboveground and underground biomass and coverage between different grazing methods. The contents of soil organic matter,total nitrogen and total phosphorus increased under the mixed grazing of yak and sheep,but decreased under the single grazing of yak or sheep. The Shannon index,Simpson index and Pielou index of soil fungi were not affected by different grazing methods. The chao1 index and Shannon index of bacteria increased under the single grazing of yak,while the Shannon index of bacteria decreased under the single grazing and mixed grazing of sheep;the diversity index of bacteria decreased significantly under the grazing of yak and sheep. The proportion of basidiomycetes in fungi was studied,and different grazing patterns had little effect on the horizontal abundance of basidiomycetes. The results of this study showed that under the same grazing intensity,different grazing patterns of yak and sheep had little effect on the grassland vegetation index,but significantly changed the soil nutrient content,the community composition of soil bacteria and fungi. Compared with single grazing of yak and sheep,mixed grazing of yak and sheep helped to improve the soil carbon,nitrogen and phosphorus content.

Key words: Grazing, Alpine grassland, Aboveground biomass of vegetation, Diversity of microbial community structure, Soil nutrients