The stability of microbial community enhanced in the rhizosphere of <i>Phragmites australis</i> at the regional scale across typical plain and plateau in China

Theoretical and empirical evidence indicates that biodiversity, species coexistence, and community stability are interconnected; however, the mechanisms underlying these associations remain poorly understood, particularly in aquatic ecosystems mediated by macrophytes. Here, we conducted a comprehensive investigation of microbial communities in bulk and Phragmites australis rhizosphere across 26 lake littoral zones of typical plain and plateau in China, and evaluated the microbial stability based on the community mean tolerance breadth, community mean response asynchrony, and network stability. We found the rhizosphere significantly enhanced bacterial and fungal richness, community mean tolerance breadth, and niche breadth compared to bulk. This enhancement was primarily driven by an overall increase in species richness, rather than by selectively promoting generalists or specialists. Rhizosphere microbial members displayed increased niche overlap and species competition, along with enhanced network complexity and stability, both within and between bacterial and fungal communities. Structural equation modeling indicated that fungal taxa exhibited a competitive advantage over bacterial members in maintaining community stability within the rhizosphere. Therefore, our study demonstrates that the rhizosphere enhances microbial community stability primarily by expanding overall species richness and intensifying competitive interactions. These findings advance the understanding of plant‐mediated microbiome stabilization and have significant implications for predicting ecosystem resilience in freshwater habitats under environmental change.