The fate of soil microbial communities under seasonal and continuous yak grazing in alpine meadows of Qinghai-Tibetan Plateau

Alpine meadows of the Qinghai-Tibetan Plateau in China are among the most degraded grasslands due to overgrazing. Soil microbial communities are an essential part of the ecosystem and are affected by environmental changes, including climate, soil properties, and grazing. This study investigated the soil microbial communities and plant and soil properties under seasonal (SG) and continuous (CG) grazing in alpine meadows. Soil organic carbon and nitrogen decreased with SG, while phosphorus decreased under grazing exclusion (GE). Plant species richness and diversity increased under GE. CG increased the microbial alpha diversity. Grazing changed beta diversity (p < 0.001) of bacterial and fungal communities. The prokaryotic and fungal OTUs were highest under GE and CG, respectively. Grazing mainly affected the fungal phyla and genera, while the bacteria and archaea showed little variation. Ascomycota were highest under summer and CG, while Basidiomycota were highest under winter grazing. SG and GE decreased the methanogenic archaea, which might have lowered the methane emissions in these grasslands. The co-occurrence network indicated that grazing affected bacterial, archaeal, and fungal communities differently. Positive interactions decreased under winter grazing, suggesting that SG might mainly affect microbial networks. SG might provide restoration time for the microbial and plant communities, maintaining the natural diversity and preventing grassland degradation.