Soil bacterial diversity is associated with human population density in urban greenspaces

Sampling

Urban greenspaces form a vital part of the urban ecosystem and provide an extensive array of ecosystem services, including pollutant degradation, water management, carbon maintenance, and nutrient cycling. However, while the soil microbiota in these ecosystems are essential to these services they remain under-characterized. Here we aimed to determine whether turf grass soil bacterial communities were associated with human population density across a range of greenspaces in parks, streets, and residential areas across a major urban area. Results showed that bacterial diversity was significantly positively correlated with population density within the immediate vicinity of the sampled areas; and species diversity was greater in park and street soils, when compared with residential zones. Population density and greenspace type (park vs street vs residential area) also associated with the composition and structure of the bacterial community. Edaphic properties, including pH, moisture and texture, were also significantly correlated with microbial composition and structure. Co-occurrence network analysis revealed that microbial guilds in urban soils were well connected. Soil moisture and texture together with population density and greenspace type showed strong correlations with several network topological features including assortativity degree, edge density, average path, average betweenness and closeness. These results indicate that changes in urban demographics, as well as the changes in land-use may influence the diversity and structure of urban soil microbial communities. As urbanization is rapidly growing across the planet, understanding the consequences of different urban zoning on soil microbiota represents an unmet need.

Method steps

1. Pipeline used: https://www.ebi.ac.uk/metagenomics/pipelines/4.1