Spatiotemporal dynamics and assembly process differ in fungal communities across contiguous habitats in tropical forests

BackgroundThe variation in fungal community composition within a single habitat space has been extensively studied in forest ecosystems. However, the spatial and temporal distribution of fungi across contiguous habitats, particularly at a local scale and in tropical regions, remains underexplored. In this study, we examined the fungal community composition across multiple habitats proximal to each other over two seasons in seven Fagaceae species in Taiwanese broadleaf forests. We tested how local spatial scale and habitat influence community assembly. ResultsUsing a metabarcoding approach, we sequenced ITS3/ITS4 amplicons from 864 samples collected from four distinct habitats--leaves, twigs, litter, and soil. We identified 11,600 fungal amplicon sequence variants (ASVs), with community composition differing significantly between habitats proximal to each other. Phyllosphere (leaves and twigs) fungi exhibited higher diversity compared to soil. Habitat type and long-term precipitation emerged as the most influential factors driving fungal diversity and composition, with a clear distance-decay relationship observed in leaf and twig but not in soil. Random forest analysis accurately classified habitats based on ASVs relative abundances, with strong predictors were mostly endemic ASVs prevalent in soil. Misclassified samples were due to secondary contact of fungi between adjacent habitats. Co-occurrence network analysis revealed more complex and deterministic networks in leaf and twig habitats, while soil was driven by stochastic processes and contained most endemic ASVs. A Cladosporium sp. emerged as a keystone species, maintaining network stability across forests. ConclusionThis study reveals how local spatial variation and habitat shape distinct fungal communities in tropical forests, with deterministic processes dominating in some habitats and stochasticity playing a key role in others. We show local fungal taxa were strong habitat predictors and drivers of community cohesion. These findings highlight the importance of studying coexisting habitats to gain a deeper understanding of fungal biogeography and ecosystem function.