Effects of Orchard Establishment on Depth-Dependent Microbial Communities in Erosion-Prone Regions of Southern China

Abstract As a novel strategy for mitigating soil erosion in southern China, orchard establishment has shown promising potential. Nevertheless, the dynamics of microbial indicators reflecting soil quality and ecosystem health during orchard establishment remain poorly understood. This investigation analyzed soil characteristics across four depth intervals (0–10, 10–20, 20–30, and 30–40 cm) in orchard plots within China’s typical erosion-prone regions and compared them with control plots lacking intervention. Orchard establishment practices increase the soil nutrient content in erosion-prone areas, improve soil aggregate stability, and thereby increase soil resistance to erosion. Moreover, the improvement in soil conditions led to an increase in soil microbial abundance and diversity, as well as alterations in community composition. However, this effect is primarily concentrated in the surface soil layer (0–20 cm) but is relatively weaker in deeper layers. Here, DR 5 − 2 (55.20%, P = 0.010) and TP (75.60%, P = 0.024) were identified as the primary environmental factors driving changes in bacterial and fungal community composition, respectively. Functional prediction analysis revealed that the OS treatment, through the introduction of specific plants, reshaped the soil microbial community from a pattern centered on decomposition and competition to one centered on symbiosis and cooperation. In summary, orchard establishment practices have profound effects on the productivity, carbon cycle, and stability of soil ecosystems in erosion-prone areas.