Drivers of soil microbial community assembly during recovery from selective logging and clear-cutting

1. Despite important progress in understanding the impacts of forest clearing and logging on above-ground communities, how these disturbances affect soil microbial beta-diversity and the ecological processes driving microbial assemblages are poorly understood. Furthermore, whether and how the microbial shifts affect vegetation composition and diversity during recovery of post-logged forests remain elusive. 2. Using a spatial grid experiment design in a primary tropical forest intermixed with post-logged patches naturally recovered for half century in Hainan Island, China, we characterized and explained the distance-decay relationships of soil microbial similarities in primary, selectively logged and clear-cut forests. 3. Selectively logged sites showed a lower spatial turnover rate of bacterial assemblages based on phylogenetic and taxonomic beta-diversity, but a higher spatial turnover rate of fungal assemblages based on phylogenetic beta-diversity, suggesting a higher level of phylogenetic variability in fungal composition. Clear-cut sites showed lower spatial turnover for both bacterial and fungal assemblages based on the two beta-diversity, indicating community homogenization. Main drivers of microbial assemblages shifted from soil properties in primary forest to tree composition in selectively logged sites, whereas microbial-tree associations declined in clear-cut sites, leading to stochastically organized microbial assemblages. 4. Synthesis and applications. The increased fungal phylogenetic turnover with tree turnover following selective logging promotes unassisted recovery of plant diversity. In contrast, the decoupling of tree and microbial turnover following clear-cutting suggests restoration approaches based on tree planting, and tree species that have strong associations with bulk soil microbial community should be considered. Our findings advance the understanding of spatial patterns, processes and drivers of soil microbial assemblages in parallel with tree community recovery during regeneration of post-logged tropical forests, and highlight the importance of coupling assemblage patterns between tree and soil fungal communities for conserving tropical forest biodiversity.