Abstract:Pinus massoniana and Cunninghamia lanceolata plantations are ecologically and economically significant forest types in China . This study investigates the interactions between soil physicochemical properties and microbial communities to elucidate the patterns and mechanisms driving shifts in microbial taxonomic and phylogenetic diversity following close-to-nature transformation. The findings aim to provide insights for the ecological management of coniferous plantations and mixed forest restoration. Soil nutrient content and basic properties were analyzed using conventional physicochemical methods, while microbial community composition was assessed via Illumina MiSeq high-throughput sequencing . The results demonstrated that: ( 1 ) The close-to-nature transformation moderately influenced soil microbial diversity in Pinus massoniana and Cunninghamia lanceolata , with an overall decreasing trend in diversity. (2)The close-to-nature transformation did not significantly alter the soil bacterial community structure in either Pinus massoniana or Cunninghamia lanceolata plantations , where Acidobacteria , Proteobacteria , Actinobacteria , and Chloroflexi remained dominant. In stark contrast, fungal communities underwent significant restructuring following the transformation, with Ascomycota and Basidiomycota emerging as the dominant phyla. Notably, the relative abundances of these two fungal groups exhibited marked divergence between plantation types. (3) Redundancy analysis (RDA) revealed that total potassium content and pH were key factors shaping bacterial community structure in both Pinus massoniana and Cunninghamia lanceolata plantations . However, none of the soil physicochemical properties analyzed in this study showed significant influence on fungal community composition . (4) Following close-to-nature forest transformation, soil bacterial communities exhibited conserved functional profiles between Pinus massoniana and Cunninghamia lanceolata plantations . In contrast, fungal communities displayed significant functional divergence. The close-to-nature transformation restructured Pinus massoniana Cunninghamia lanceolata plantations , modifying soil properties and optimizing fungal communities for enhanced ecological adaptation.