Bacterial, fungal, and archaeal community assembly patterns and their determining factors across three subalpine stands at different stages of natural restoration after clear-cutting

Purpose The knowledge regarding how different soil microbial groups change in subalpine forest areas after clear-cutting is limited. To bridge this gap, we studied the change patterns of the different soil microbial community assemblies and their determining factors in subalpine areas. Materials and methods Field measurements and sampling were conducted in three stands at different stages of natural restoration (BF, broadleaf forest; MF, mixed coniferous and broadleaf forest; and PCF, primeval coniferous forest) after clear-cutting in western Sichuan Province, China. Three soil microbial group (bacteria, fungi, and archaea) community assemblies, edaphic properties, soil nematodes, tree diameter at breast height, plant richness, and understory vegetation biomass were examined and statistically analyzed. Results and discussion The alpha-diversity of the three microbial groups in the BF and MF stands was significantly higher than that in the PCF stand. The difference between the stands was greater than the difference within the stands for all three microbial groups. The changes in the three microbial groups were all significantly associated with shifts in soil carbon, soil total nitrogen, soil available nitrogen, and tree species composition. The bacterial and archaeal communities were also closely related to the bacterivore number. Acidobacteria, Actinobacteria, Bacteroidetes, Planctomycetes, Basidiomycota, Ascomycota, and Thaumarchaeota were the main phyla that responded to environmental variation. Conclusions The three soil microbial groups all showed regular trends across the three different stands. The changes in the soil microbial community assembly were mainly attributed to the differences in soil nutrients, tree species composition, and feeding traits of soil nematodes.