In order to explore the impacts of the land use conversion from a Phyllostachy pubescens (moso bamboo) forest to a Torreya grandis cv. Merrillii plantation, as well as the cultivating years of the T. grandis cv. Merrillii plantation, on the soil microbial community, this research studied the soil microbial structure and diversity of a moso bamboo forest, T. grandis cv. Merrillii plantations (5, 10, and 30 a), and a T. grandis cv. Merrillii-mountain rice interplanting plantation (5 a) using the high-throughput sequencing technique, and the relationship between the microbial community and environmental factors was further explored. The results showed that after the land use change, the Shannon index and Chao1 index of the soil bacterial community increased significantly; the Simpson index increased significantly in the 30 a T. grandis cv. Merrillii plantation, whereas the Shannon index decreased significantly. Both the Simpson index and Chao index of the soil fungal community had no significant difference under different land use types. whereas the Shannon index was significantly decreased in the 30 a T. grandis cv. Merrillii plantation. PCoA analysis of the soil microbial community at the genus level showed that land use type played a vital role in driving the changes in soil bacterial and fungal communities. The compositions of the soil microbial communities between the two 5 a stands were most similar. The dominant phyla of soil bacteria mainly included Acidobacteria, Proteobacteria, Actinobacteria, and Chloroflexi. The results of cluster analysis showed that the soil bacterial community changed significantly at the genus level after the conversion of land use; the abundance of most dominant bacterial communities decreased with increasing cultivation. The fungal community was mainly composed of Ascomycota, Basidiomycota, and Zygomycota, whose changes in community characteristics were similar to those of bacteria. The results of RDA analysis showed that pH, organic matter, available phosphorus, available potassium, and water-soluble organic carbon and nitrogen were significantly correlated with soil microbial community. Therefore, these soil fertility properties might be the driving factors affecting the structure of bacterial communities. This study provided a theoretical basis for solving the problem of soil quality deterioration in T. grandis cv. Merrillii stand land management.
Keywords: Torreya grandis cv. Merrillii; cultivation history; high-throughput sequencing; land use conversion; microbial diversity.