Correlations between dominant vegetation type and composition and diversity of soil bacterial communities in a subtropical forest

Single and mixed vegetation types have significant effects on soil parameters and the composition and diversity of soil bacterial communities. To understand the influence of different vegetation types on the structure of soil bacterial community across soil depth in a subtropical forest, we assessed the relative abundance of edaphic bacterial community and soil parameters, including pH, cation exchange capacity (CEC), and dissolved organic carbon (DOC) in Daiyun Mountain Nature Reserve in Fujian Province, southeastern China. The study area constitutes pine coniferous forest (CF) of pinus taiwanensis, broad-leaved forest (BF) of castanopsis fabri, and a mixed forest comprising CF and BF (MF). Quantitative PCR and Illumina sequencing of 16S rDNA were used to analyze the abundance, diversity, and composition of soil bacteria. The results showed that the pH, CEC and diversity of tree species are all associated with the composition of the bacterial community in the soil. It was found that CEC, soluble organic nitrogen (DON) and pH largely affected the structure of soil bacterial community in A horizon, whereas CEC, moisture content (MC) and organic phosphorus (OP) affected the structure of soil bacterial community in B horizon. We found that the dominant taxa in the CF and BF were Proteobacteria and Acidobacteria, respectively. The results of both mental and random forest (RF) analyses displayed groups according to vegetation types, indicating that the bacterial communities in the research site were significantly influenced by vegetation types in subtropical forests. The study highlights the ecological effects of forest management and elucidates the differences in the functional structure of soil bacterial communities under different vegetation types and soil depths.