the cities issue Nature in the City

The forest in the city

Sandy Smith pinpoints the value of trees in urban areas by Andy Torr

Why do cities have to be bleak, cemented, glassed-in places?”

It’s a rhetorical question, and Sandy Smith seems exasperated at having to ask it.

As a professor of forestry and one of only a handful of urban foresters in Canada, she’s a tireless advocate for trees in city settings. It’s a difficult task. After all, for decades, legions of city planners and landscape architects have treated trees as mere decora- tions, or worse, removed trees altogether to make way for more glass and concrete, manicured lawns and decorative flowerbeds.



But those old attitudes are changing, Smith says, and she believes the urban forestry profession has come a long way since it was pioneered by U of T’s Erik Jorgensen in the early 1960s.Today,city planning bureaus around the world are making room for urban foresters, and experts like Smith are playing a key role in multidisciplinary teams of city planners, landscape architects, engineers, developers, geographers and sociologists.

“It’s not just about planting pretty flowers and grass,” Smith explains, “it’s about planting things that provide services. Urban forests combat air and water pollution, they reduce water runoff, and they provide shade and protection. We estimate the trees on U of T’s St. George campus alone generate $170,000 each year in these soft services. If you consider our heavily forested Scarborough and Mississauga campuses, that dollar amount increases significantly across the U of T system.”

This figure also doesn’t consider the biological or human benefits of trees, Smith says, noting that human brains are literally wired for trees. Studies have repeatedly shown that forests are vital for our health, finding correlations between a loss of tree canopy and a rise in cardiovascular and pulmonary disease, for example, or charting a dip in gun violence in urban areas where trees were found.

Still, urban foresters must navigate a bewildering array of considerations. What type of trees should be planted, and where? How large will they grow, and how long will they live? What services will they offer? Even a decision to plant native or non-native trees has implications: a recent study by U of T forestry graduate student Eric Davies found that native city trees contained 25 times more bird and insect activity than their non- native counterparts.

It’s this kind of science, Smith says, that ultimately helps policy-makers, planners, developers and architects to make more responsible and sustainable decisions: “We’re using what we know about the natural world to inform how we design cities.”

    EDGE / Fall 2013