Metal-driven bacterial community variation in urban and suburban park soils of Shanghai, China

Abstract

Urban greenspaces, including parks, provide essential ecosystem services, and in which soil bacteria play vital roles in nutrient cycling, carbon sequestration, pollutant degradation, and promotion of the mental and physical well-being of residents. However, how did the bacterial distribution respond to the varying environmental variables along with urbanization in park soils remain unclear. In this study, by using Illumina Miseq sequencing combined with geochemistry analysis, the bacterial community structure and their response to soil variables were investigated in 30 parks from urban and suburban areas in Shanghai, China. The results showed that the soil organic matter (SOM), total nitrogen (TN), phosphorous (TP), chromium (Cr), copper (Cu), zinc (Zn), bioavailable potassium (AK), sulfur (AS), copper (ACu) and zinc (AZn) were significantly higher in urban park soils than suburban park soils. In contrast, the soil pH, EC, and bioavailable magnesium (AMg) in suburban park soils were significantly higher than those in urban park soils. Bacterial Shannon diversity was higher in suburban park soils than that of urban parks. Bacterial community structure between urban and suburban park soils showed a significant difference. Chloroflexi KD4-96, Chthonomonadetes, and Bacteroidia were significantly higher in suburban park soils, while Bacilli, Chloroflexi JG30-KF-CM66, and Clostridia were significantly enriched in urban park soils. The results of the Mantel test revealed that various metal concentrations, including Cd, AZn, Zn, ACu, Cu, Cr and AMg, had a significant impact on the bacterial communities in urban park soils, while Cd and K were determined to be the most influential factors shaping the bacterial communities in suburban park soils. The results of this study will help to further understand how the bacterial community responds to environmental variables in the city ecosystem.