Diversity, biogeography, and assembly of fungal communities in Chinese mangrove sediments

Fungi are essential to mangrove wetlands, yet the mechanisms governing their community assembly across environmental scales remain elusive. Utilizing high-throughput amplicon sequencing across seven representative mangroves along the Chinese coastline, we characterized the distribution patterns and hierarchical assembly mechanisms of the sediment mycobiome. Our results reveal that mangrove sediments serve as a major reservoir of taxonomic novelty, harboring abundant phylum-unclassified species and widespread non-Dikarya lineages. Site identity exerts a stronger influence on community variance than mangrove plant, with dispersal limitation and mean annual temperature shaping macro-scale patterns. Locally, salinity and C/N ratio function as prominent environmental filters that constrain fungal communities, while total phosphorus exerts a notable indirect facilitative effect. The inter-domain co-occurrence network is dominated by synergistic associations, featuring a prokaryotic backbone and specific fungal nodes with high topological centrality. Piecewise structural equation modeling confirms that fungal community assembly is regulated by a scale-dependent hierarchical framework integrating macro-climatic filtering, local edaphic filtering, and micro-scale biotic associations. In summary, this study provides a theoretical foundation for understanding microbial community stability in coastal ecosystems under global change.