Forest Succession Shapes Soil microbial Communities through Region-specific Edaphic Filters in Tropical and Subtropical Forests

Understanding how soil microbial communities respond to forest succession is essential for predicting ecosystem functions and biogeochemical stability. We investigated bacterial and fungal communities across three successional stages (early, mid, late) and three soil depths (0–10, 10–20, 20–50 cm) in forests of Pakistan and China using high-throughput amplicon sequencing of 108 soil samples. This cross-regional, depth-resolved study aimed to determine whether microbial successional trajectories and soil–microbe relationships are general or region-specific. Preliminary results showed that the forest succession was accompanied higher soil organic carbon (SOC), total nitrogen (TN) and declined soil pH in Pakistan. It indicates consistent acidification and potential phosphorus limitation in mature stands. Whereas SOC and total potassium (TK) exhibited mid-successional peaks in China, that indicates different resource/nutrient dynamics. Mid-forest successional stages showed maximum bacterial diversity, whereas late succession revealed the highest fungal diversity (kingdom-specific responses). Community composition shifted from copiotrophic taxa in early stages to oligotrophic taxa in mature forests. Soil pH was the most influential factor shaping microbial composition in Pakistan, whereas potassium availability was the most influential factor in China. These cross-regional, depth-resolved results reveal both successional patterns and region-specific environmental controls, offering new insights into microbial community composition during forest development and providing guidance for forest restoration and soil-carbon management across biogeographically diverse regions.