Emma Hudgins

McGill University
Estimating damages to urban trees from US invasive forest pests

Emma J. Hudgins, Frank H. Koch, Brian Leung

Urban trees are the main target of economic damages due to invasive forest pests in the United States. Estimates of damages due to pest species are frequently cited in the literature (263 citations) and used in policy recommendations (ISPM15), but are currently out of date. This project combines three existing frameworks to more accurately estimate future damages to US urban trees due to invasive forest pests. We build off of 1) an existing economic approach to estimate pest damages (Aukema et al. 2011), 2) a recent modelling framework for US urban tree distributions (Koch et al. 2018), as well as 3) forecasts of all-species forest pest spread derived from earlier work during my PhD. Using these three frameworks, we combine per-tree damage estimates for each pest species, with models of urban tree distributions for all tree genera within ~30 000 urban communities across the United States, and with predictions of each tree’s infestation status from pest-specific spread models. This approach modifies the existing damage estimates to incorporate species-specific spread predictions for 63 pest species, and allows us to more accurately forecast future damages across space due to its finescale spatial resolution of urban tree distributions.