COS 282-2 - Changes in urban tree community structure across socio-urban gradients reflect discrepancies in ecological function between advantaged and disadvantaged communities.

Background/Question/Methods

Urban greenspaces provide numerous benefits to their local communities impacting mental and physical health, energy consumption, water dynamics, and more. Numerous studies have found that urban green spaces are often unequally distributed in cities and particularly lacking in impoverished and minority-dominated areas. The present study expands on these past works by further exploring how urban tree community structure (referring to quantity, size, and composition) varies across a socio-urban gradient. We predict that urban forest structure is strongly reflective of the severe economic and social segregation associated with past urban design. The study utilizes forest biometric data collected in Syracuse, NY between 2009-2019 to measure the difference in species composition, plot basal area (m2/ha) and plot density (trees/ha) across a socio-urban gradient. We quantified this gradient using multivariate analysis that encapsulates thirteen socioeconomic and landscape variables converted into two dimensions using a Highly Clustered PCA. The resulting axes represent aggregate scales in ‘Wealth and Race’ (Dim1) and ‘Age and Education’ (Dim2).

Results/Conclusions

Results suggest that as areas increase in wealth and proportion of White citizens (represented as high values on Dim1) there is a significant increase in tree basal area and plot density (both p < 0.05), with preference for native species over naturalized or invasive. For areas with greater levels of education and dominated by the 18-35 age demographic (representing high values on Dim2), we see a decrease in tree basal area but stronger relative abundance of invasive and large naturalized species over time (all p < 0.05). Both dimensions were also significant in influencing the species composition of urban tree communities (Mantel’s R = 0.75, p = 0.001; Adonis-p < 0.05). However, Dim2 trends may be unique to college towns with similar institutional influences on population demographics and should be evaluated in non-college towns. The dimension also reflects the need to evaluate the impact of other potentially influential institutions on the urban tree community. Overall, these results emphasize the need for continued investment in increasing planting and management of native species in disadvantaged neighborhoods to promote an equal distribution of environmental services across the city.