Abstract
Management decisions grounded in ecological understanding are essential to the maintenance of a healthy urban forest. Decisions about where and what tree species to plant have both short and long-term consequences for the future function and resilience of city trees. Through the construction of a theoretical damage index, this study examines the legacy effects of a street tree planting program in a densely populated North American city confronting an invasion of emerald ash borer (Agrilus planipennis). An investigation of spatial autocorrelation for locations of high damage potential across the City of Toronto, Canada was then conducted using Getis-Ord Gi*. Significant spatial clustering of high damage index values affirmed that past urban tree planting practices placing little emphasis on species diversity have created time-lagged consequences of enhanced vulnerability of trees to insect pests. Such consequences are observed at the geographically local scale, but can easily cascade to become multi-scalar in their spatial extent. The theoretical damage potential index developed in this study provides a framework for contextualizing historical urban tree planting decisions where analysis of damage index values for Toronto reinforces the importance of urban forest management that prioritizes proactive tree planting strategies that consider species diversity in the context of planting location.
Highlights
Recognized for providing important ecological, economic, and social benefits to city residents (Dwyer et al, 1992; McPherson, 1992), urban tree cover is a living resource and inherently dynamic (Nowak and Greenfield, 2012)
With an increasing number of large North American cities like New York and Los Angeles investing in planting programs to protect and enhance their urban forests (City Plants, 2015; Million Trees NYC, 2015), it is important to investigate how city tree management choices driven by short-term considerations
This study considers an example of these consequences that are, in part, a legacy of past planting decisions concerning the street tree resource in Toronto, Canada, currently facing sudden and rapid canopy loss resulting from Emerald Ash Borer or “EAB” (Agrilus planipennis), an invasive, phytophagous, insect pest
Summary
Recognized for providing important ecological, economic, and social benefits to city residents (Dwyer et al, 1992; McPherson, 1992), urban tree cover is a living resource and inherently dynamic (Nowak and Greenfield, 2012). Avoidance of high rates of street tree mortality (Foster and Blaine, 1978; Lu et al, 2010) and stultified tree growth (Close et al, 1996; Quigley, 2004; Smiley et al, 2006) are practical and attractive reasons for selecting fast growing tree species that are more tolerant of urban conditions. Such decision making serves to improve the short-term efficiency of urban tree planting programs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
