Composition and interaction frequencies in soil bacterial communities change in association with urban park age in Beijing

[Display omitted] •Soil microbes play an important role for performing essential ecosystem services in urban parks.•Park age was associated with shifts in bacterial community composition but not diversity.•Park construction was associated with a short-term effect on interactions among soil microbial taxa. Soil microbes play an important role in pollutant remediation and nutrient cycling in urban green spaces. However, how microbial composition and diversity are affected by environmental factors is poorly understood. Here, we compared soil microbial communities in 11 urban parks, constructed at different times (10, ∼30 and >100 years ago) or existing in their natural state. The dominant phyla in the samples were Proteobacteria, Bacteroidetes, Actinobacteria, Gemmatimonadetes, Verrucomicrobia, and Planctomycetes. The relative abundance of some phyla showed significant differences between natural forest parks and urban parks. Park construction over a period of time led to significant differences in microbial community structure, which was also significantly correlated with soil pH, moisture, total nitrogen, total carbon, and soil bulk density. Bacterial diversity was significantly positively correlated with pH, and species diversity was not significantly different in each successive park age category. Co-occurrence network analysis revealed that microbial guilds in urban soils were well correlated. Abundant soil microbes in natural forests and hundred-year-old parks had fewer interactions, while abundant bacteria in ten-year-old and thirty-year-old park soils had more interactions. Our results indicate the influence of urban park ages on soil microbial communities, which is important for understanding the effect of urbanization on soil microbes.