Linking topography, soil physicochemical traits and bacterial community dynamics in a managed tea landscape.

Topography significantly shapes soil properties and microbial community structure, influencing ecosystem function and agricultural productivity. This study examined the upland-lowland gradient in a tea-growing landscape to assess how topographic variation affects soil physicochemical and biological properties, and bacterial community composition. Soils were sampled from upland tea fields, lowland paddy fields, and an intermediate transition zone. Upland tea soils were highly acidic (pH 3.7–4.5) with higher organic carbon content, favoring the presence of Acidobacteria, Patescibacteria, and other oligotrophic taxa known for roles in organic matter turnover. Lowland paddy soils, in contrast, exhibited higher moisture and enzymatic activities corresponds to anaerobic and facultative anaerobic taxa such as Moraxellaceae and Rhodobacteraceae. The transition zone, characterized by moderate pH, organic carbon, and minimal human disturbance, exhibited the highest bacterial diversity, including nitrogen-cycling taxa like Burkholderiaceae. Organic carbon was strongly correlated with community composition, particularly with the abundance of Actinobacteria. These findings highlight the strong interdependence between topographic variation, soil health, and microbial functional processes. Implementing topography-informed soil management practices is critical for preserving microbial diversity, enhancing nutrient cycling efficiency, and sustaining long-term soil fertility within agricultural ecosystems.