Homogeneous Selection and Dispersal Limitation Drive Phyllosphere Fungal Community Assembly in Constructed Wetland Ecosystems

Constructed wetlands (CWs) are widely used for ecological restoration, but their microbial assembly mechanisms and ecological functions remain poorly understood, limiting the optimization of restoration strategies. In this study, we investigated foliar fungal communities associated with dominant plant types in a CW converted from farmland by employing high-throughput sequencing. We analyzed community composition, diversity, assembly processes, and co-occurrence network structure to identify potential keystone taxa. Our results showed that plant type significantly influenced fungal community diversity and composition (α < 0.05). Assembly processes were jointly driven by heterogeneous selection (36.48%), dispersal-related processes (35.49%), and drift (24.70%), indicating comparable contributions of deterministic and stochastic processes. Co-occurrence network analysis revealed a modular structure and identified several hub taxa based on topological indices, suggesting their potential importance for network stability. This study provides an integrated perspective that links community diversity, assembly mechanisms, and network structure, providing insights for improving CW vegetation management and microbial regulation strategies. Future studies should explore and validate the functional roles of hub taxa and test the generalizability of these patterns across multiple regions and seasons.