Analysis of fungal community structure and co-occurrence networks across vegetation types in volcanic lava habitats

The eruption of Wudalianchi Volcano directly damaged the soil and vegetation, forcing succession to restart from bare land. It influenced subsequent vegetation succession. This study utilizes the Wudalianchi volcanic lava plateaus as a model, employing high-throughput sequencing to unravel the drivers of soil fungal diversity across a vegetation gradient: moss (M), herb (H), shrub (S), broadleaf forest (B), and mixed coniferous-broad-leaved forest (C). This study found that <i>Ascomycota</i> (43.39%-71.54%) and <i>Basidiomycota</i> (5.36%-53.21%) were the dominant phyla. <i>Ascomycota</i> peaked in the C community, whereas <i>Basidiomycota</i> was most abundant in the M community. At the genus level, <i>Cortinarius</i>, <i>Mortierella</i>, and <i>Scleroderma</i> dominated in the B, H, and M communities, respectively. For fungal communities, Shannon and Chao indices followed the order: S > H > C > M > B. Co-occurrence network analysis indicated the greatest complexity and connectivity in the S community, which had the most nodes, links, and the highest average degree. Fungal functional guilds shifted across the gradient: symbiotrophic fungi prevailed in the B and M, while saprotrophic fungi dominated H and C communities. Soil physicochemical properties were the primary determinants of fungal community structure and function. In conclusion, significant differences exist in the structure, diversity, and function of soil fungal communities across different vegetation types in volcanic lava habitats. Soil TP, pH, and N/P ratio were identified as key drivers, with shrub vegetation playing a critical role in fostering complex fungal networks and functional balance. This study underscores the key regulatory role of specific soil properties and vegetation succession in shaping fungal communities, providing a framework for understanding microbial assembly in extreme environments.