Effect of stand age on soil microbial communities of a plantation Ormosia hosiei forest in southern China

Abstract Changes in soil environmental factors and microbial communities of a precious tree species (Ormosia hosiei) plantation with different forest ages are still unclear. Obtaining this information can provide a theoretical basis for scientific forest management. Ormosia hosiei plantations of varying ages (7, 20, and 45 years old) were targeted in Zhejiang Province, China. We collected surface soil (0–20 cm) and analysed the diversity and structural characteristics of soil microbial communities by high-throughput sequencing. Redundancy analysis (RDA) and Spearman correlation analysis revealed soil environmental factors that cause differences in the microbial communities. The soil bacterial community diversity was not significantly affected by stand age, while the Chao and Ace indexes of the fungal community at 20 and 45 years were markedly higher than those at 7 years. The abundance of Proteobacteria in the 45 years was lower than those at 7 and 20 years, while the abundance of Actinobacteria at 7 years was lower than those at 20 and 45 years, and the abundance of Basidiomycota gradually increased with increasing stand age. The RDA and correlation analysis indicated that the soil microbial biomass carbon (MBC), bulk density (SBD), total porosity (STP), and total potassium (TK) were key factors that affected the bacterial communities and had a significant correlation with Actinobacteria. Soil temperature (T), available phosphorus (AP) and forest litter (FL) affected the fungal communities and had a significant correlation with Basidiomycota. In conclusion, forest age did not affect bacterial diversity, but the soil fungal community of the O. hosiei plantation in the middle-aged forest (20 years old) had the highest diversity; there were obvious differences in the composition and structure of soil microorganisms between different forest ages, which may be attributed to the phyla present (e.g., Proteobacteria, Actinobacteria, and Basidiomycota), which may be caused by differences in T, SBD, STP, AP, TK, MBC, and FL.