Abstract: Urban environments are increasingly recognized as unique ecosystems for testing basic and applied theories in ecology. There is an ever-growing literature on the impact of these gradients on many classes of organisms. However, soil fauna communities are rarely studied in urban ecological studies. Here, we attempted to partially fill this knowledge gap by examining drivers of soil fauna abundance, diversity, and function along a rural-urban gradient of 40 public parks in Rochester, NY. We related the diversity and functional richness of soil fauna communities to spatial, pedologic, socioeconomic, and urbanization metrics. As landscapes became more urban (i.e., imperviousness and population density increased), we expected both soil fauna biodiversity and richness to decrease. Second, we expected urbanization to diminish functional redundancy in soil communities. Finally, we expected that contrary to the luxury effect hypothesis, which states that biodiversity is positively related to socioeconomic status, socioeconomic status would negatively correlate to measures of soil fauna diversity and richness due to the relatively high public utilization of high-income parks.
To test these hypotheses, we enumerated soil animal communities in public parks across an urban gradient in spring and fall over 2 years, along with gathering data on plant communities and soil physical and chemical properties at each sampling site. In our analysis, we utilized both traditional statistical approaches and machine learning to disentangle the factors contributing to urban soil fauna community composition. Contrary to our expectations, our findings show that soil animal species richness and diversity are not negatively related to urbanization, and in some instances, urbanization may enhance soil fauna communities. Further, our results show that urbanization may create both top-down and bottom-up forces on soil foodweb functional groups, which may lead to less functionally redundant soil fauna communities. Finally, we found that measures of soil fauna community composition are often negatively related to socioeconomic status. Our results suggest that contrary to current thinking, urban greenspaces, and their soil microarthropod communities can be surprisingly diverse, which indicates their potentially important role as reservoirs for biodiversity and soil ecosystem services in urban areas, especially in historically neglected or marginalized areas.
