Mechanism of the Effects of Phyllostachys edulis Invasion on the Soil Microbial Community in Quercus acutissima Forests

In recent years, the invasion of Phyllostachys edulis has intensified. This study selected Phyllostachys edulis, Phyllostachys edulis-Quercus acutissima mixed and Quercus acutissima forest areas and analyzed the changes in soil bulk density, porosity, water-holding capacity, pH, soil organic carbon (SOC), soil readily oxidized organic carbon (ROC), soluble organic carbon (DOC) and microbial biomass carbon (SMBC). Then, we obtained the Chao index, Shannon index and Simpson index and analyzed the relationship between microbial alpha diversity, beta diversity and community composition, abundance and structure and between microbial community changes and environmental factors. The results showed that soil with the invasion of Phyllostachys edulis, soil pH, water content, capillary water capacity and total porosity of surface soil increased significantly by 4.35%, 18.71%, 16.37% and 14.56%, respectively, compared with the Quercus acutissima forest, while soil bulk density, organic carbon, microbial biomass carbon and soluble organic carbon decreased significantly by 7.27%, 18.43%, 61.12% and 61.90%. Soil readily oxidized organic carbon decreased at first and then increased. The soil community richness and diversity of the Phyllostachys edulis forest were significantly greater than those of the other two stands. Soil pH and organic carbon content were the main factors affecting the changes in the soil microbial community. Therefore, the invasion of Phyllostachys edulis improved soil water retention, while soil pH had the greatest effect on the microbial community, followed by soil bulk density and organic carbon, and water content had the smallest effect.