Rhizosphere fungal community assembly varied across functional guilds in a temperate forest

Background Rhizosphere fungi play an important role in plant community dynamics and biogeochemical cycling. While the drivers of fungal community assembly have been studied in varied ecosystems, it is still unclear how these processes function for rhizosphere soil fungi in temperate forests. Furthermore, it is unknown whether the relative contributions of important determinants remain consistent or vary across fungal ecological guilds. This study used high-throughput next-generation sequencing to characterize the fungal communities of 247 rhizosphere soil samples from 19 tree species in a temperate forest within Northeast China. We aimed to investigate how three important determinants in temperate forests (host tree species, neighbouring plant communities, and edaphic properties) influence the community assembly of fungal functional guilds in the rhizosphere soil of trees. Results We found that host tree species contributed more to plant pathogens’ community composition than ectomycorrhizal fungi, and plant pathogens consistently showed higher host specialization than ectomycorrhizal fungi. Saprotrophs also showed high host specialization, which was mediated by the tree species’ effect on rhizosphere soil pH. Although neighboring plant communities contributed remarkably to richness of all fungal guilds, this effect on fungal composition varied across functional guilds, with stronger effect for biotrophic guilds (plant pathogens and ectomycorrhizal fungi) than for non-biotrophic guild (saprotrophs). Neighboring plant communities shaped the ectomycorrhizal community composition strongly in all samples regardless of host trees’ mycorrhizal type, whereas edaphic properties were the most important drivers for this guild in samples from only ectomycorrhizal-associated trees. Edaphic properties played an important role in shaping ectomycorrhizal and saprotrophic fungal compositions, indicating the importance of edaphic properties on the fungal functional guilds associated with the absorption and decomposition of nutrients. Conclusions These results demonstrated that rhizosphere soil fungal community assembly determinants varied across fungal guilds, reflecting their different ecological functions in temperate forest ecosystems.