Thinning alters the network patterns and keystone taxa of rhizosphere soil microbial communities in Chinese fir plantation

The composition and structure of microorganisms, which are affected by management practices, play a crucial role in controlling the function of forest ecosystems. Although the response of microbial communities to thinning has been well studied, the effect of thinning on the cooccurrence patterns of soil bacteria and fungi, especially in rhizosphere soil, remains unclear. In this study, we investigated the bacterial and fungal communities in rhizosphere and bulk soil of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook) plantations under different thinning intensities, including control (CK, 0 %), light-intensity thinning (LIT, 30 %), moderate-intensity thinning (MIT, 50 %), and high-intensity thinning (HIT, 70 %). Fungi were more sensitive to thinning than bacteria, with their diversity in bulk soil being decreased after thinning. Thinning-sensitive operational taxonomic units (tsOTUs) were taxonomically diverse, with each thinning intensity harboring a specific tsOTU subset. The top 3 modules in the meta-cooccurrence network were dominated by the phyla Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Ascomycota, and Basidiomycota, which showed little overlap and were affected by thinning. In addition, we identified 16 and 3 thinning-sensitive keystone taxa in the rhizosphere and bulk soil, respectively. The highest abundance of these 16 keystone taxa was detected in the rhizosphere soil after HIT. Overall, we demonstrated that thinning altered the composition, cooccurrence network, and keystone taxa of soil bacteria and fungi. These findings indicated detectable thinning-induced changes of largely unknown consequences in the composition of the rhizosphere soil communities, suggesting that rhizosphere soils should be considered in future studies.