Diversity patterns and drivers of soil microbial communities in urban and suburban park soils of Shanghai, China

BACKGROUND: The rapid expansion of urbanization leads to significant losses of soil ecological functions. Microbes directly participate in key soil processes and play crucial roles in maintaining soil functions. However, we still have a limited understanding of underlying mechanisms shaping microbial communities and the interactions among microbial taxa in park soils. METHODS: In this study, the community variations of bacteria and fungi in urban and suburban park soils were investigated in Shanghai, China. Real-time PCR and high-throughput Illumina sequencing were used to examine the microbial abundance and community composition, respectively. RESULTS: The results showed that soil molecular biomass and fungal abundance in urban park soils were significantly higher than those in suburban park soils, while no significant difference was observed in the bacterial abundance between urban and suburban park soils. The alpha diversity of soil microbes in urban and suburban park soils was similar to each other, except for Chao1 index of fungal communities. The results of similarity analysis (ANOSIM) revealed remarkable differences in the composition of bacterial and fungal communities between urban and suburban park soils. Specifically, park soils in urban areas were enriched with the phyla Methylomirabilota and Verrucomicrobiota, while the relative abundance of Gemmatimonadota was higher in suburban park soils. Moreover, the fungal class Eurotiomycetes was also enriched in urban park soils. Compared with suburban park soils, nodes and average paths of the bacterial and fungal networks were higher in urban park soils, but the number of module hubs and connectors of the bacterial networks and negative interactions among bacterial taxa were lower. Compared with suburban park soils, Acidobacteriota bacterium and Mortierellomycota fungus played more important roles in the ecological networks of urban park soils. Soil available zinc (Zn), available nitrogen (N), pH, and total potassium (K) significantly affected fungal community composition in park soils in Shanghai. Soil available Zn was also the most important factor affecting the bacterial community composition in this study. CONCLUSION: There were significant differences in the soil molecular biomass, fungal abundance, and the community composition and co-occurrence relations of both soil bacterial and fungal communities between urban and suburban park soils. Soil available Zn played an important part in shaping the structures of both the bacterial and fungal communities in park soils in Shanghai.