Influence of urban-form and sociodemographic factors on street tree abundance transpire across scales in Houston, TX

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 the distribution of street trees across Houston, Texas. We used three measures (green view index, street tree canopy, 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 street tree abundance. Our analysis indicates that the effects of urban-form and sociodemographic determinants on street tree abundance disparities operate at varying spatial scales across Houston. Overall, ‘building coverage ratio’ and ‘percent residential land use’ play primary roles in shaping the distribution of street tree abundance in east Houston while effects of “percent renter occupied” and “median house value” are more pronounced in west Houston. Our results also show that urban-form and sociodemographic factors interact with each other at spatial scales ranging from a few neighborhoods to several districts to the entire 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.