Abstract: How climate warming impacts soil microbial diversity and composition has long been a focal point in the research area of biodiversity and ecosystem function. However, the extent to which different levels of warming affect soil microbial communities in alpine meadow ecosystems remains largely unknown. We conducted a field experiment with different warming levels (W1, W2 and W3 respectively represented a gradual increase in temperature) in an alpine meadow of Yushu, Qinghai Province, and investigated soil microbial communities using high-throughput sequencing. The results showed that: (1) Climate warming significantly increased soil bacterial α-diversity and β-diversity. Specifically, the Shannon index of soil bacteria was increased by 2.70%, 3.87%, and 8.73% under the W1, W2, and W3 treatments, respectively, while the Chao1 index of soil bacteria was increased significantly by 17.82% under the W3 treatment (P<0.05). (2) Acidobacteria and Proteobacteria were the dominant bacterial phyla, while Ascomycota and Basidiomycota were the dominant fungal phyla. As temperature increased, the abundance of bacterial taxa increased, whereas the fungal population decreased. (3) Functional prediction of bacteria and fungi based on the PICRUSt and FUNGuild databases revealed changes in the potential metabolic functions of bacteria and ecological functions of fungi after climate warming. Functional genes with relative abundances exceeding 2% under different warming levels included Biosynthesis of ansamycins, Biosynthesis of vancomycin group, and Valine, leucine, and isoleucine biosynthesis pathways. Warming increased relative abundances of uncategorized saprotrophic fungi and arbuscular mycorrhizal fungi. These findings demonstrate that climate warming would alter soil microbial community diversity, composition, and function in alpine meadows of the Qinghai-Tibet Plateau.

Key words: Qinghai-Tibet Plateau, alpine meadow, climate warming, soil microbial community, functional prediction.