Association for Public Policy Analysis & Management

There is compelling evidence that urban trees provide local public benefits, including benefits to the environment, public health, and to the local community. Likewise, scholars have amassed evidence that poor and minority communities in cities often have less access to urban trees, including tree canopy cover and trees planted in the public right of way (street trees). If poor and/or minority residents have unequal access to these amenities, then they also have unequal access to the benefits those amenities provide, evidence of environmental injustice. Previous city-specific research has found that urban trees are not equally distributed within cities by income. However, results are more mixed regarding the distribution of urban trees by race and ethnicity. Both the city-specific nature of and conflicting results across existing studies suggest a need for a research synthesis to draw broader conclusions.

We propose a meta-analysis of the relationship between urban tree canopy cover and (i) race and ethnicity and (ii) income. We will conduct a systematic and exhaustive literature search to identify original studies that empirically examine the relationship between urban tree canopy cover and socio-demographic characteristics. This analysis will contribute to our current knowledge in the area in two key ways. First, we will estimate in the average effect size, a measure of the unconditional relationship between tree canopy cover and (i) race/ethnicity and (ii) income. Second, we are interested in identifying the drivers of variation in these estimates such as inclusion of potentially important control variables or the type of model used. To examine these drivers, we will use a meta-regression framework which will allow the relationship between tree canopy cover and socio-demographic characteristics to be examined in greater depth.