Green space biodiversity in the shrinking city

Background/Question/Methods

The urban core of many traditional, post-industrial cities has been steadily emptying (e.g., Cleveland, Detroit, St. Louis, Pittsburgh), something that represents a major challenge to a city’s sustainability.  Migration to the suburbs has also led to significant socioeconomic disparities within the urban core, further challenging sustainability policies. The bulk of urban ecology research has focused on the impact that urban sprawl has on populations, ecosystems, and landscapes. Alternatively, little attention has been given to the role that the depopulation of the urban core has had on biodiversity. We investigate if the soil diversity of public parks in St. Louis city is responding to socioeconomic status of the surrounding neighborhoods. We surveyed soil invertebrates in six city parks. Parks were selected based on the socio-econimic gradient of the city (lower in the north side, higher in the south), as well as park area (small, medium, large).  All parks are under city management.  Within each park we established a tree cover treatment (open vs cover), and set a 1m² quadrat, at the corners of which we measured soil compaction, pH, and relative soil humidity. A pitfall trap was set at each corner in order to sample the epigaeic invertebrate community. All invertebrate collections were identified to the lowest taxonomic resolution possible. Parks were surveyed in July, and September of 2011, and  May 2012. We used an unreplicated nested ANOVA for determining if effects were present, and at what scale.

Results/Conclusions

Preliminary analysis suggest that St. Louis parks’ soil biodiversity is responding not just to the effects of area and cover, but to larger scale influences that are usually not considered in classical biodiversity model, eg, socio-economic status.  The way that tree cover, watering, recreational activities, etc, occur in a park reflect not just the management policy of the city, but also the cultural influences of the surrounding neighborhood.  How exactly is that biodiversity is interacting with our cultural and social process is complex and needs further investigation.