Slope gradient but not slope position affecting microbial community composition in the cropland of typical black soil region

Soil microorganisms are the main driving force in soil ecological and biogeochemical processes, such as carbon mineralization, humus formation, and nutrient cycles. Soil erosion may dramatically alter microbial properties. However, it is still unclear how soil microbial characteristics affected by soil erosion. In hilly areas, soil erosion is highly attributed to topographic characteristics such as slope position and slope gradient. Herein, we compared the soil microbial characteristics between different slope gradients and positions in the farmland in the typical black soil area of Northeast China. The relative abundances of major microbial phyla are illustrated. Proteobacteria, Acidobacteria, Gemmatimonadetes, Planctomycetes, and Actinobacteria accounted for 83% of the total bacterial sequences, and Ascomycota, Basidiomycota, and chytridiomycosis accounted for 78% of total fungal sequences in the studied area. Microbial alpha-diversity (Bacteria and Fungi) was similar among the slope gradients or slope positions. The bacterial and fungal community composition was only affected by slope gradient, which was significantly lower in the highest slope gradient level than in others. This study suggests that slope gradient but not slope gradient affecting microbial community composition in the cropland of black soil region.