A bumper crop of acorns in 2023 gave a boost to Toronto’s cutting-edge urban forest plan, which aims to transition the city to a native ecosystem.
“Last year was a mast year for oaks… a huge amount of seed,” said Kim Statham, Toronto’s director of urban forestry. “Walk around any oak-dominated neighbourhood, and you would have heard acorns dropping all over the place. Pretty fantastic.”
The result of that mast year wasn’t just good news for squirrels. It means the city’s tree seed diversity program gained tens of thousands of seeds which will be planted at a nursery to sprout into native tree seedlings for the city’s urban forest.
Trees make a city liveable, says Eric Davies, a professor of forestry at the University of Toronto who has been involved in collecting the tree seeds. Toronto’s 11.5 million trees sequester carbon from the environment, keep the city cool and perform evapotranspiration — the process of moving water from soil to the atmosphere.
Plus trees make us feel better. That’s not an urban myth. People really do feel better when they are exposed to nature, Davies says.
“People are happiest and healthiest in healthy environments. And that’s what’s really cool. They’re finding all around the world and every continent, wherever, that people are way happier when they’re in a forest that’s healthy and an ecosystem that’s healthy, has freshwater and fresh air and biodiversity,” he said. “They don’t know why they feel better. They just feel better.”
Foresters know why they feel better. It’s not just any trees and plants that make people healthier. It’s the biodiversity native trees support that makes us feel better.
But for a healthy dose of biodiversity, what’s needed is native plants — plants that interact in healthy ways with insects, birds and soil, says Davies.
Hence Toronto foresters’ goal to slowly transition the city’s tree canopy back to mostly native species.
Currently, many of Toronto’s trees are the Norway maple, a non-native, invasive species. For decades, Davies says, the embraced goal of urban planners and foresters everywhere has been to achieve a 40 per cent tree canopy — no matter the type of tree.
Urban foresters likely planted so many Norway maples because the tree is beautiful and hardy. It can survive salted roads, poor drainage and questionable soil quality. Its ability to block sunlight, its abundant seed production and its leaves that are toxic to insects and pollinators mean it can squeeze out native plants.
This latter feature is a “huge problem,” Davies says. “[Early foresters] just thought, ‘if it looks like a tree and you know, sways like a tree, it’s a tree.’ But it’s not the tree that is needed,” Davies said. The tree that is needed is one that supports biodiversity and that means a tree native to this area.
There are about 70 species native to the Toronto area, including sugar maples, red, black, white and burr oaks, hickories and white and red pines. The city, which plants about 120,000 trees a year, can’t get its hands on enough of these trees. Commercial nurseries do not produce them in that quantity. So the city must produce them itself.
City within a park
In 2013, Toronto adopted a strategic forest management plan. The plan aims to increase the city’s tree canopy cover to 40 per cent, ensure the canopy covers the city fairly, increase public awareness of the value of trees and, perhaps most importantly, increase biodiversity to improve the urban forest’s resilience and response to climate change.
Then in 2021, the city partnered with Forests Ontario, a non-governmental organization dedicated to improving the province’s forests, to kick off a 10-year tree seed diversity program. Forests Ontario collects the seeds and grows the trees to supply the city’s tree-planting program.
Sometimes volunteers help with the city’s tree seed diversity programs, including collecting seeds. In 2023, students from the Toronto French School, a private school that emphasizes an appreciation of nature, gathered tens of thousands of seeds as part of their nature studies. Davies, who is the school’s forest ecologist, says the students made “a historical contribution to improving the health of the city.”
Maryann Shemansky, Toronto French School’s manager of communications, said the school was an early adopter of environmental education. Since about 2008, it has had “eco leaders” who take the students into nature as part of their studies. The school is ideally situated for this as it sits on 28 acres of land that backs onto Toronto’s ravine system.
Toronto has been called a city within a park because of its distinctive ravine system, the largest in any city in the world. The system forms a large urban forest that runs through most of Toronto. Because development is severely curtailed in the ravine, large native trees grow in abundance there.
“We started intentionally thinking about the ravine and nature deficit disorder [which afflicts some urban people] and the importance of that for children’s physical and mental health,” Shemansky said. The students work on projects to study the ravine, map, record and identify trees and plants. It was a natural progression that they would help with the city’s tree seed diversity program, Shemansky says.
Is Toronto cutting edge when it comes to trees? When asked, Statham will concede Toronto is doing well with its tree programs, which also include planting, tending and pruning the city’s trees and educating people about the value of trees.
“I fully admit that I’m biased. But I’m often told time and time again that Toronto really is a leader in urban forest management and other municipalities will look to see what Toronto is doing,” Statham said.
“I would say that we have some very unique programs here. We have a very supportive city council who are interested in this,” she said. “I’m not suggesting that we have it all figured out. There’s lots of very good work ahead as we evolve and look to urban forest management as a key critical component to climate resiliency.
“But I would argue that Toronto has an incredible resource. We have a lot of support and interest, and we’re doing some really cool things.”
