Abstract: Vegetation types affect the structure and function of terrestrial ecosystems and landscape patterns, as well as the structure and function of soil microbial communities. This study selected 10 vegetation types including slope farmland, check-dam farmland, orchard garden, artificial caragana korshinskii shrubland, artificial Robinia pseudoacacia forest, abandoned farmland, Artemisia sacrorum grassland, Periploca sepium shrubland, Sophora viciifolia shrubland, and Platycladus orientalis forest for sampling in the loess hilly region. Soil physico-chemical analysis and soil microorganisms 16srRNA gene using high-throughput sequencing technologies analysis were used to reveal the characteristics of the soil bacterial community structure and function, and to identify the relationship between environmental factors and soil microbial community among different vegetation types. The results showed that Proteobacteria and Actinobacteria were the dominant groups of soil microorganisms in the soil bacterial community, followed by Acidobacteria, Chloroflexi, Gemmatimonadetes, Bacteroidetes and Verrucomicrobia. The α diversity index of soil bacterial community under natural vegetation types was slightly higher than that under artificial vegetation types, but only ACE index of soil bacterial communities had significant differences among different vegetation types (P<0.05). The similarity clustering analysis based on genus level reflected that the similarity relationship of different soil bacterial communities can objectively related to the characteristic of different vegetation types. Unknown function, and amino acid transport and metabolism were the dominant functional groups in the soil bacterial community. RDA analysis showed that total carbon, total nitrogen, organic carbon, electrical conductivity, pH, nitrate nitrogen, and soil moisture were the key environmental factors which affected soil bacterial community. Correlation heatmap analysis showed that there was a significant correlation between the dominant genera and environmental factors. Vegetation types had an important influence on the composition and function of soil bacterial community. The characteristics of soil microbial community showed a comprehensive response to the biological characteristics of dominant species, vegetation succession, soil properties, and human management of different vegetation types. Therefore, vegetation types is an important driving factor for soil bacterial community structure and function in the Loess Hilly Region.

Key words: vegetation types, soil microbe, high-throughput sequencing, diversity, environmental factor