Functional and biogeographical properties of urban soil communities have long been neglected owing to the human-dominated nature of urban ecosystems. As recognition of the value of ecological functions performed by urban soils has increased, it has become more important to understand how bacterial and fungal communities are distributed across the many types of urban microhabitats, and how these patterns relate to ecological functions performed by the respective communities. The emergence of green roofs, bioswales and other types of soil-based green infrastructure in major cities worldwide constitutes the emergence of designed or engineered habitats amid urban landscapes, further highlighting the importance of characterizing urban microbial biogeography. In this study we investigated whether green roofs and bioswales in New York City, as engineered habitats, had distinct microbial communities compared to non-engineered soils--parks and tree pits. We then assessed whether bacterial and fungal communities in these habitats exhibited differences in functional traits.
Results/Conclusions
Using 16S- and ITS- based metagenomic amplicon sequencing, we found that green roofs and bioswales each have distinct bacterial and fungal communities. Community composition and diversity were not significantly associated with geographic distance, suggesting that the processes structuring these differences are related to aspects of the habitats themselves. Bioswales, and to a lesser extent green roofs, also exhibited elevated functional potential, based on the diversity and relative abundance of taxa associated with a range of functional traits, including nitrogen cycling, biodegradation, decomposition and various functions positively associated with plant growth. We discuss these results in the context of community assembly theory and with respect to urban sustainability.