Clarifying the response of soil microbial communities to the change of different vegetation types on a small regional scale is of great significance for understanding the sustainability of grassland development. However, the distribution patterns and driving factors of the microbial community are not well understood in the Qilian Mountains. Therefore, we characterized and compared the soil microbial communities underlying the four vegetation types in a national natural reserve (reseeded grassland, swamp meadow, steppe meadow, and cultivated grassland) using high-throughput sequencing of the 16S rRNA and ITS. Meanwhile, the plant community and soil physicochemical characteristics were also determined. The results showed that bacterial and fungal communities in all vegetation types had the same dominant species, but the relative abundance differed substantially, which caused significant spatial heterogeneities on the small regional scale. Specifically, bacteria showed higher variability among different vegetation types than fungi, among which the bacterial and fungal communities were more sensitive to the changes in soil than to plant characteristics. Furthermore, soil organic carbon affected the widest portion of the microbial community, nitrate-nitrogen was the main factor affecting bacteria, and aboveground plant biomass was the main factor affecting fungi. Collectively, these results demonstrate the value of considering multiple small regional spatial scales when studying the relationship between the soil microbial community and environmental characteristics. Our study may have important implications for grassland management following natural disturbances or human alterations.

Aims This study explored the trends in soil fungal patterns and their responses to carbon and nitrogen during the succession in Alpine grassland in the Qilian Mountain area. Methods Illumina sequencing of ITS genes was used to characterize the soil fungal construct, and the FUNGuild database to predict functional groups in Alpine grassland succession from swamp meadow to alpine meadow, steppe meadow. Soil carbon and nitrogen, vegetation carbon and nitrogen, and soil enzyme activity were also investigated. ResultsThe soil fungal OTUs increased with succession in the rst stages but then reached a relatively stable state in the second successional stages. The sobs and Chao1 index showed the same trend as OTUS during succession. And there are signi cant differences in fungal community structure among different succession stages. During succession, most phyla showed linear decreases trends; whereas Ascomycota showed linear increases. The relative abundance of Pathotroph and Saprotroph of fungal functional increased with the successional stages, while the Symbiotroph had no change during succession. We also found that NH4 + -N is the dominating factor, which affects the structure of fungal community across all successional stages, and soil microbial carbon has the greatest in uence on the variation of functional communities.Conclusions Our ndings indicate that the community dramatically shifted with succession in the rst stages but then reached a relatively stable state in the second successional stages, while the soil fungal function group did not follow this rule. NH4 + -N and soil microbial carbon had the greatest in uence on the community and function of fungi, respectively.