Moso bamboo invasion changes the assembly process and interactive relationship of soil microbial communities in a subtropical broadleaf forest

Abstract

Moso bamboo (Phyllostachys edulis) invasion into adjacent broadleaf forests has been widely observed across subtropical China, and has induced negative effects on aboveground biodiversity. However, how bamboo invasion influences soil microbial community structure and assembly process remains largely unknown. We investigated the changes in diversity, structure and assembly processes of bacterial and fungal communities in an evergreen broadleaf forest following Moso bamboo invasion. Soil samples were collected from three forests (a pure Moso bamboo forest, an adjacent mixed bamboo-broadleaf forest, and a non-invaded broadleaf forest) along twelve invasion transects. Our results showed that bamboo invasion increased soil pH and decreased the contents of soil organic carbon (SOC), dissolved organic carbon (DOC), total and available nitrogen and phosphorus nutrients. Bamboo invasion significantly increased the diversity indices (i.e., OTU richness and Shannon index) of both bacteria and fungi and changed their community compositions (P < 0.05). Bamboo invasion significantly decreased the relative abundance of Actinobacteria and Basidiomycota whereas increased those of Ascomycota and Mortierellomycota. The co-occurrence network analysis displayed more connected and complex relationships of both bacterial and fungal communities in bamboo forest. Bamboo invasion increased the community-level habitat niche breadths of both bacterial and fungal communities due to increased abundances of generalists. The stochastic process of bacterial and fungal community assembly weakened and the deterministic process enhanced generally as a result of bamboo invasion. The migration rate of bacterial communities (0.615) was higher than that of fungal communities (0.037), indicating that dispersal limitation less affect bacteria taxa. Random forest model demonstrated that DOC content, followed by mineral N, were the most important factors mediating the bacterial and fungal community assembly. Taken together, our results suggest that bamboo invasion strongly altered the assembly of bacterial and fungal communities by regulating the deterministic-stochastic balance, which deepens our understanding of the role of bamboo invasions on ecological processes.