Microbial Community Structure and Diversity of Idesia polycarpa Under Different Mixed Planting Systems

This study investigated the effects of different mixed−planting regimes of Idesia polycarpa on soil microbial community structure and diversity in the source region of the Huai River. Four planting systems were examined: pure forest, I. polycarpa + Camellia oleifera, I. polycarpa + C. oleifera + peanut, and I. polycarpa + peanut, designated as TB1, TB2, TB3, and TB4, respectively. Highthroughput sequencing was used to characterize changes in soil microbial composition and diversity among planting systems. The results showed that: (1) Mixed planting significantly altered soil microbial community structure. Compared with other treatments, TB4 exhibited significantly higher soil pH than TB1, TB2, and TB3 (p < 0.05), as well as higher− available potassium, alkali−hydrolyzable nitrogen, and organic matter contents than TB1 (p < 0.05). (2) The Chao and Shannon indices of soil microbial communities in TB3 were significantly higher than those in TB1, indicating enhanced microbial richness and diversity. (3) The RDA results showed that the overall model was not statistically significant (p = 0.496), indicating that no significant relationships between the measured soil environmental factors and bacterial community variation were identified in this study. Overall, TB3 exhibited relatively higher bacterial diversity, whereas TB4 showed a more favorable soil nutrient status. These findings suggest that soil properties and microbial community characteristics may vary among planting patterns. Future studies should expand sampling across multiple sites, increase sample sizes, and employ more robust statistical approaches to further investigate the relationships between planting patterns, soil properties, and microbial community characteristics.