Toronto looks to expand tree canopy with planting on private land

As the city of Toronto works to build more housing, it faces another challenge too: less space for trees, which the city is trying to plant in large numbers to improve air quality, reduce storm water runoff and cool city streets as summers heat up.

The city says it wants to increase its tree canopy — the amount of city streets shaded by trees — to cover 40 per cent of Toronto by 2050. As of a 2018 city review, the canopy covered about 30 per cent. To do so, it aims to plant about 120,000 trees a year.

As part of Earth Month, the city is encouraging homeowners to apply for a free tree to be planted and watered on the roadway by their property. It's a decades-old program that the city is pushing this month through a poster campaign.

The city's director of Urban Forestry says adding more trees can be tricky in a crowded city with limited space and a need for more housing.

"We are certainly balancing housing with livable cities and and trees and urban forests being part of that," said Kim Statham, director of Toronto's Urban Forestry branch. "So we also promote a program on private land."

In some North American cities, half of the canopy is on private land, says Dr. Stephen Sheppard, professor emeritus at the University of British Columbia's Urban Forestry Program.

Sheppard says the city of Toronto's residential street tree planting program is a good way to incentivize more planting in residential areas but housing needs do pose an obstacle. Facing a housing crunch and homelessness crisis, the city is committed to building 285,000 homes by 2031, and council recently allowed fourplexes in an effort to increase density.

"The government has to effectively reduce canopy by densifying and building," said Sheppard. "This is a real push-pull challenge on how we're going to balance those policies."

Tree canopy mitigates warming impacts

Trees in urban settings provide a variety of benefits, including cooling. The city is marketing trees as a way for homeowners to increase their property value. But as Toronto faces hotter summers and worseningair pollution from wildfire smoke, the health benefits could be massive too.

The city is encouraging residents to apply for free tree planting outside their properties through a poster marketing campaign this Earth Month. (Julia Alevato/CBC)

Covering two-fifths of a city with tree canopy is ideal for keeping neighbourhoods cool and keeping air clean, says Sheppard.

"The tree canopy helps a lot to kind of buffer those kinds of impacts and reduce the risks," he said in an interview. "Trees are a natural air conditioner. A healthy tree canopy is the only way of cooling entire neighbourhoods."

They also filter out air pollution, and in other areas, reduce flash floods and landslides, he says.

But Janet McKay, executive director of LEAF, a local tree-planting company, says development can vastly reduce the amount of space trees can thrive in some neighbourhoods. LEAF is under contract with the city, which subsidizes the company to plant trees in backyards of homes in neighbourhood improvement areas.

"So yeah, it's a big challenge," she said. "We certainly need more housing. We also want to live in a city that's livable and offers the benefits that trees provide us."

'Can't live in a city without them'

Developers sometimes have to remove existing trees, and even though the city plants a tree for every one that's removed, McKay notes that they don't have to be planted in the same area. That can leave some streets leafy and shaded, while others become depleted of the soil needed to sustain trees.

"Trees really can only grow where they've got adequate soil volume and where water can infiltrate the soil and actually get to their roots," McKay said.

Housing density, like that seen in this neighbourhood in Ajax, could help address housing needs in the GTA. But density poses a challenge to urban forests. (Ed Middleton/CBC)

It's something Statham, of the Toronto's Urban Forestry branch, calls an "inequitable distribution of forest across the city."

But she says more homeowners across the city are applying to have trees planted.

"We certainly have seen a rise in interest both politically as well with the public as folks are becoming more environmentally and ecologically conscious, knowing that trees play a critical role in the climate resiliency and livability of our cities," said Statham.

McKay says developing and densifying housing can't come at the cost of the tree canopy.

"The benefits that trees provide us, everything from, cleaner air and visual [aesthetics] and sound barriers in a very busy city, to mental health benefits, physical health benefits," she said,

"We really just can't live in a city without them."