COS 226-5 - Spatial overlay of forest fragmentation and social vulnerability highlights high risk census tracts in urban counties across the United States

Abstract: Greenspace is a natural resource often unavailable in dense urban communities, particularly areas of lower socioeconomic status. Environmental justice (EJ) involves addressing the historical discrimination against marginalized groups and ensuring equitable distribution of ecosystem services moving forward. Issues regarding EJ are prevalent in many urban areas in the United States, and we hypothesize that increasing forested land connectivity through urban centers can be seen as one avenue to begin to alleviate these disparities. Benefits from increased tree cover include bolstering ecosystem services such as cleaner air, mitigated urban heat, and improved physical and mental health for adjacent residents. Forest fragmentation reduces a forest’s ability to provide these benefits and decreases overall resiliency. In this study, we view the primary importance of intact forests as providing essential ecosystem services that help improve and maintain life in surrounding communities, and we emphasize the value of ensuring the equitable distribution of forest area and green spaces. Using urban counties from across the US in North Carolina, Maryland, and Washington as case studies, we compared forest fragmentation trends in areas of widely different total tree cover.



We created a risk matrix to identify hotspots that are both high in social vulnerability and high in forest fragmentation. We quantified forest fragmentation based on class cohesion values using the National Land Cover Database tree canopy cover rasters and social vulnerability by the CDC Social Vulnerability Index (SVI). As a test of the effects of forest connectivity on ecosystem service delivery, we also consider the relationship between urban heat and forest patch cohesion, with our results indicating a significant negative correlation. Using GIS to uncover spatial connections between decreased ecosystem services and socioeconomic disadvantages is useful for focusing community aid and improving land management practices in the areas that need it most. Census tracts in more densely populated urban areas are more likely to have disconnected, isolated patches of forest land. These areas are also more likely to have high social vulnerability, a value that is based on a variety of socioeconomic variables including spatial factors such as housing density and crowding. Mapping hotspots of high land cover fragmentation and SVI can identify areas that could benefit from community improvement efforts.