Disentangling the effects of urban form and socio-demographic context on street tree cover: A multi-level analysis from Montréal

摘要

Street trees provide a wide range of benefits for cities. Street tree cover (STC) is explained by urban form, social stratification and lifestyle theories that operate at multiple scales. In this paper we examine how the urban form (street characteristics), social stratification and lifestyle (socio-demographics) account for variations of STC in Montréal. Tree cover was identified from Quickbird images and then overlaid on street segments to compute the STC. Each street segment was nested in a census tract. We used 2-level models with mixed effects and interactions (between street attributes and socio-demographic variables) while introducing a spatial term. Political, socio-economic or other explanatory factors operating at the tract level can potentially explain 17.6% of the variation of STC. Overall, the street characteristics explained more variation in STC than the socio-demographic context. Lifestyle is less important than social stratification. Street length is positively associated with STC; street width and the percentage of duplexes and triplexes are negatively associated with STC, while construction age has a u-shaped effect on STC. Interactions show that STC is higher in expensive and highly-educated areas that have residential streets or streets with large setback (sidewalk). Areas predominantly comprised of low-income households could have higher or lower STC depending on the number of buildings and the percentage of duplexes and triplexes. Streetscape and socio-demographic contexts intertwine to create complex patterns of STC. Greening programs should be designed carefully according to local contexts since certain types of greening can lead to gentrification and displacement of low-income households.