Forest Patch History, Species Composition, and Structure and their Relationship to Inequitable Access to Biodiversity and Ecosystem Services

Urban systems are highly heterogeneous, and minority and low-income residents often have less access green spaces and biodiversity. This inequity has a long legacy that is related to the ecological and—the often racially biased—developmental history of cities, and rectifying these injustices is a major focus of current urban planning. This research compared the distribution, species composition, and structure of forest patches to census-derived socio-demographic data to better understand differences in access to forests, biodiversity, and ecosystem services. To do this, we identified forest patches across the Chicago Metropolitan Region using a morphological spatial pattern algorithm on a 1 m resolution tree canopy layer. We then characterized each patch's development history by comparing them to pre-settlement (circa 1840) and 1940s forest maps. To quantify species composition in these patches, we sampled 120 plots and found that development history was a good predictor of forest composition, with remnant forests having more native species than patches that experienced recent clearings. Additionally, we used aerial and terrestrial LiDAR to quantify the structural complexity of these patches and found differences that also related to forest patch history. Finally, we compared the forest patch distribution, diversity, and structure to socio-demographic data and found that lower income and minority communities not only had less access to forest patches overall, but that the patches that were near them were more likely to contain shrubby, invasive species and to be denser. Forest patches are important providers of ecosystem services—spending time in them has been found to reduce stress and to improve impulse control and cardiovascular health. However, people need to directly interact with forests to receive these benefits, and the dense structure and low diversity may make the forests that under-resourced communities have access to less inviting to visit. These results indicate a need for the protection of remnant forest patches, but also for increased management of existing patches and intentional afforestation projects in under-resourced communities to improve equitable access to ecosystem services.