Urban forests should be comprised of a wide diversity of species in order to reduce vulnerability to pests, extreme weather events, and other disturbances. Homeowners, along with other local actors, influence urban forest composition based on their species selection decisions. Recent research suggests homeowners have limited tree species identification abilities and typically choose trees to plant in their yards based on aesthetic and functional traits (e.g. showy flowers, fruit production, mature size), not by species-type or with species diversity goals in mind. Thus, a gap exists between municipalities, who have adopted species diversity goals to increase urban forest resilience, and homeowners’ tree selection priorities.
This presentation will describe a socially-relevant measure of tree diversity (referred to as the social attribute index) that we developed, which captures the aesthetic and functional traits that reflect residents’ priorities when selecting trees. The social attribute index was then calculated for residential properties in southern Ontario and compared to ecological diversity metrics (species richness and percent native species) to better understand the relationship between socially-relevant and ecologically-relevant measures of urban forest diversity. Household socio-ecological data were also collected.
Results/Conclusions
Across the 54 urban residential properties in our sample, we recorded 478 trees representing 88 unique species. The number of trees per property was quite variable (between one and 22 trees) with an average of seven species present. At the property-level, the social attribute index has a strong positive relationship with species richness, but there was no relationship with the percent native species present. Additionally, neither the social attribute index nor species richness is related to homeowners’ socio-demographics collected through the companion survey, suggesting residents’ species selection decisions are based on individual preferences and/or specific site conditions. The presentation will end with a discussion of strategies to increase species diversity in the urban forest that are better aligned with residents’ existing knowledge and goals, including encouraging aesthetic diversity as a pathway to increase species richness and evenness.