Soil Microbial Community Varied with Vegetation Types on a Small Regional Scale of the Qilian Mountains

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.