Spatial inequalities in street-tree abundance transpire across scales in Houston, TX

Keywords: Socio-spatial inequality, environmental justice, urban vegetation, urban trees, urban morphology
Abstract Type: Paper Abstract

Abstract

Benefits provided by street trees can be enjoyed by all urban residents but trees along these public rights-of-way are usually unevenly distributed in a city. Both urban form and sociodemographic factors can influence the spatial distribution of street trees. However, little is known how the relative importance of urban form and sociodemographic characteristics on street-tree abundance inequalities vary across neighborhoods. In this study, we explored spatially varying influences of urban form and sociodemographic variables on heterogeneous distribution of street trees in the city of Houston. We used three indicators (green view index, street tree canopy cover, and street tree density) to measure street-tree abundance. We then built multiscale geographically weighted regression (MGWR) models to capture the spatial heterogeneity in the influence of urban form and sociodemographic factors on these three green measures. Our analysis indicates that the effects of urban form and sociodemographic determinants on street tree disparities operate at varying spatial scales across Houston. ‘Building coverage ratio’ and ‘percent residential land use’ are the two urban form factors that are significant on street trees across the entire city. However, these city-wide factors are strongly affected by sociodemographic ones at spatial scales ranging from a few neighborhoods to several districts within the city. These scale- and location-specific nuances in our findings provide important insights to develop the kinds of urban planning strategies to attain increasingly equitable distribution of street-tree abundance across an urban area.