If a Tree Falls in the Urban Forest: Current and Future Pest Vulnerability in Toronto's Urban Forest

Urban forests represent a valuable resource for cities. Accounting for species diversity and vulnerability to pests when managing an urban forest can help enhance services delivered and minimize management expenses. In this research, tree genera currently prevalent and commonly planted in Toronto were analyzed using a pest vulnerability matrix to explore how the city's urban forest's pest vulnerability may be changing. Current tree species composition was derived from inventory data, while the planting trends of a variety of local actors were determined through surveys and interviews. Results suggest some genera show clumped distributions and occasionally surpass recommended diversity thresholds in a given district or citywide. On-going planting behaviours in Toronto are replicating some current diversity issues while also increasing less common species. As a result, Toronto's vulnerability to tree pests and diseases will likely decrease, but certain serious issues will continue.