Relationships between soil fungal and woody plant assemblages differ between ridge and valley habitats in a subtropical mountain forest.

Elucidating interactions of above-ground and below-ground communities in different habitat types is essential for understanding biodiversity maintenance and ecosystem functioning. Using 454 pyrosequencing of ITS2 sequences we examined the relationship between subtropical mountain forest soil fungal communities, abiotic conditions, and plant communities using correlation and partial models. Ridge and valley habitats with differing fungal communities were delineated. Total, saprotrophic and pathogenic fungal richness were significantly correlated with plant species richness and/or soil nutrients and moisture in the ridge habitat, but with habitat convexity or basal area of Castanopsis eyrei in the valley habitat. Ectomycorrhizal (EM) fungal richness was significantly correlated with basal area of C. eyrei and total EM plants in the ridge and valley habitats, respectively. Total, saprotrophic, pathogenic and EM fungal compositions were significantly correlated with plant species composition and geographic distance in the ridge habitat, but with various combinations of plant species composition, plant species richness, soil C : N ratio and pH or no variables in the valley habitat. Our findings suggest that mechanisms influencing soil fungal diversity and community composition differ between ridge and valley habitats, and relationships between fungal and woody plant assemblages depend on habitat types in the subtropical forest ecosystem.