Mapping the Urban Forest — One Data Point at a Time

Photo by Joan Sorolla. Paso del Prado de Madrid.

When a resource as valuable as our urban tree canopy isn’t widely understood, the resulting knowledge gap between what we think our city trees are capable of and what they’re actually contributing to our health and wellbeing can have deep consequences.

In late August I attended a stakeholder meeting at Ryerson University in downtown Toronto. Andrew Millward, a Ryerson geography professor and co-founder of Citytrees, was speaking with representatives from school boards, conservation authorities and municipalities. He was talking about trees.

Millard has led the creation of a web-app called Citytrees, an online tool that aims to give citizen scientists, urban planners, private residents and large institutional landholders the opportunity to plot the location, species type and health of trees in their care. He figures that armed with a little knowledge about how our urban forest ecosystems are absorbing CO2, cooling buildings and reducing stormwater runoff, we all will be more inclined to care for the trees in our midst.

Earlier this week, a piece I wrote about Citytrees — ‘The app doesn’t fall far from the tree’ — went online at I encourage you to check it out to learn more about the value of urban trees and the Ryerson team trying to spread the word.

Here’s a small excerpt from the piece:

Andrew Millward, co-founder of Citytrees and a geography professor at Ryerson, says the idea for the app was inspired by his time on campus. “I’ve observed a lot of reactionary responses to everything urban tree-related here, from downed to infected trees,” he told a stakeholder meeting in August. The campus has more than 500 trees, he said, but little data on their diversity, age, or condition is captured in municipal forest management plans.

“Urban forests should be viewed as one large ecosystem and not as a collection of disjointed and disconnected patches of trees,” Millward tells me via email. Currently, though, the information we have about them is gathered and kept by a variety of different groups. “Our goal is to connect all of these data in a virtual sense,” he says, “and help us to understand the interconnectedness and interdependence of our urban forest as an ecosystem.”

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