Canopy of advantage: Who benefits most from city trees?

Urban tree canopy provides a suite of ecological, social, and economic benefits to the residents of urban areas. With an expanding recognition of these benefits among city residents, there is growing concern that access to these benefits is not distributed equally and may represent the presence of an environmental injustice. This study examines the spatial relationship between median household income and tree canopy variables, specifically realized tree canopy cover and potential tree canopy cover, for Toronto, Canada. Toronto provides a strong empirical focus as it is a densely populated urban setting reported to be exhibiting an increase in the geographic polarization of residents based upon household income. Spatial relationships between median household income and tree canopy variables are evaluated using the bivariate Moran's I statistic, a specialized local indicator of spatial autocorrelation (LISA). This method explicitly identified where statistically significant spatial clusters of high and low household income coincide with significant clusters of high and low urban tree canopy, providing the basis for an examination of the policies and management decisions that led to this temporal snapshot. The importance of these spatial clusters is examined from the perspective of understanding the impact of urban change (both socio-demographic and built form), and from the standpoint of improving equality of access to city trees and their benefits resulting from future tree planting decisions.