Contrasting diversity and community assembly of leaf- and root-associated bacterial communities from 13 tree species in a subtropical forest

Abstract Background Deciphering the local diversity and community assembly of plant-associated microorganisms is crucial to better predict the ecological functioning in forest ecosystems. The differences in microbial diversity and community assembly pattern between plant aboveground and belowground compartments, however, are less documented. Here, we examined the bacterial communities in the leaf- (endophytic and epiphytic) and root- (root and rhizospheric soil) associated habitats of 13 tree species in a subtropical forest ecosystem. Results The bacterial α-diversity (phylotype richness) substantially differed across the four habitats, with the highest and lowest values observed in soil and leaf endophytic compartments, respectively. The variations of α-diversity amongst the 13 tree species were more obvious in leaf endophytic and epiphytic habitats than in their corresponding roots and soils. The bacterial community compositions were different across the four habitats and were significantly more divergent in leaf- than in root-associated habitats. Moreover, deterministic processes dominated the endophytic and epiphytic community assembly, whereas stochastic processes primarily affected community assembly in root and rhizospheric soils. Leaf nutrients (nitrogen and phosphorus) and soil pH were the main factors influencing leaf- and root-related community compositions, respectively. Conclusions This study highlights the contrasting diversity and community assembly patterns between leaf- and root-inhabiting bacteria. Our findings contribute to a better understanding of the maintenance mechanisms of microbial diversity in the subtropical forest ecosystem.