Tracing the family tree
An effort to catalogue Toronto’s oldest, most majestic trees is a key step toward preserving the city’s canopy.
Toronto’s biggest and tallest trees are rare survivors, the last bastions of a former landscape. Engineering marvels, they cool our cities and clean our air. The oldest, most majestic ones overwhelm with their beauty. By these measures, these giants belong in a museum. Yet despite their ecological and historical significance, there is currently no overarching plan to protect — or even to catalogue —Toronto’s very large, old trees.
“Imagine if we treated historical artifacts the way we treat these trees,” says Eric Davies, an ecologist who is identifying and mapping significant native trees in Toronto’s ravines.
“In most of the city, we don’t know where they are, we don’t know how big they all are, or if they are healthy.”
“These trees are the oldest, largest living things in Toronto,” adds Davies, who is pursuing his PhD at the University of Toronto’s Faculty of Forestry.
“We should be protecting them with the same kind of passion that we give to great works of art.”
Without a baseline tally of the city’s big, old trees, there is no way to judge the full impact when one dies or is cut down.
As Davies points out, it’s hard to protect something when you don’t know how many you have in the first place.
In hopes of spurring a larger movement to find and map the city’s biggest, oldest trees, Davies has shared his data set of significant ravine trees with the Star.
He knows the 905 trees he has mapped so far — more than half of which measure almost one metre in diameter — are just a small sample of the big and old specimens among Toronto’s 10.2 million trees. Still, he says, his inventory is a necessary start.
Toronto has long touted itself as a treefilled city with its parklands, shady streets and vast network of forested ravines.
Current estimates suggest the urban forest canopy covers about 28 per cent of the city, and a 2017 study by the Massachusetts Institute of Technology, in collaboration with the World Economic Forum, ranked Toronto fifth in the
world for its canopy cover — ahead of Los Angeles, New York, London and Paris.
Around the world, many cities are aiming for 40 per cent canopy cover to maximize the benefits of trees.
Toronto has also pledged to reach that ambitious goal and, according to city budget documents, aims to plant 120,000 a year on public property and in city-owned road allowances.
The city’s Strategic Forest Management Plan says that won’t be enough; some 300,000 trees need to be planted on private property every year to reach the canopy cover target.
While planting new trees is a critical component of Toronto’s tree strategy, tree advocates say more needs to be done to protect and care for the city’s biggest trees.
Not just for their beauty and ties to our past, but because the bigger the tree, the bigger the benefits — from cleaning and cooling the air to soaking up floodwaters and increasing property values.
According to the city’s own calculations, a tree with a trunk diameter greater than 75 centimetres (29 inches) can capture10 times more pollution and can store up to 90 times more carbon than a 15-centimetre tree.
Currently, just 14 per cent of Toronto’s trees, whether growing in backyards, parklands or neighbourhood streets, have trunk diameters larger than 30 centimetres (about a foot), and a much smaller percentage of this are exceptionally large trees. The average Toronto tree is roughly 16 centimetres in diameter.
Philip van Wassenaer, a consulting ar- borist at Mississauga’s Urban Forest Innovations Inc., says too many large trees are unnecessarily cut down or overly pruned because too few people have the knowledge or skills to properly care for them.
Combine that with the increasing pressures of urban development, disease, drought, storms and insects, and it’s no wonder, van Wassenaer says, that Toronto is losing more and more of its large, valuable trees.
“Some of these trees are hundreds of years old. What confounds me is that we, who should be stewards of these trees, can so easily decide to get rid of them, and generations of history instantly disappears.”
In Toronto, a permit is required to cut down a privately owned tree with a trunk diameter of 30 centimetres or more. Further bylaws protect street trees and trees growing in parks and ravines.
Asmall percentage of Toronto’s big, old tree population is protected under the private tree bylaw, which says trees with heritage recognition, as determined by Forests Ontario or through the Ontario Heritage Act, cannot be injured or removed without a city council vote.
According to a city spokesperson, there are currently 41trees with heritage designation in Toronto, as well as three groves and three remnant forests.
Councillor Glenn De Baeremaeker (Ward 38, Scarborough Centre, and not running in the upcoming election) has been the city’s tree advocate.
He agrees Toronto’s biggest, oldest trees should be accounted for in a biological inventory, ideally one that
“A 250- or 300-year-old oak tree takes a long, long, long time to get that big. We need to keep them, value them, protect them.” SANDY SMITH UNIVERSITY OF TORONTO
would take stock of both the giant trees and the health of the forests in which they grow.
De Baeremaeker says city council has prevented the removal of heritage trees “99 per cent of the time,” but adds the city and citizens need to be better stewards of what he calls “cathedral trees,” which he likens to great works of art.
“When people buy a house with a 100year-old tree in the backyard, they have to know they are taking on a Mona Lisa tree,” he says.
“There has to be more awareness, education and even a moral imperative from citizens that if you do own a Mona Lisa tree, you have to care for it and protect it.”
Earlier in 2018, a massive 250-year-old red oak growing in a North York back- yard prompted heated citywide discussions about who is responsible for preserving Toronto’s oldest, largest trees.
A realtor representing owners of the bungalow on Coral Gable Dr. said the city needed to purchase the property or the tree, which was threatening the structural integrity of the house, would be chopped down.
In July, council approved a plan to begin negotiations with the homeowners to acquire the property, with provisions the red oak is deemed healthy and at least half of the funds used to purchase the house come from private donations.
Since 1985, New York City has maintained a heritage tree registry of mature trees that are unusual in size or shape or have a historical tie to the city.
Residents can, through the NYC Parks Stewardship Program, volunteer to be tree stewards to help with their care.
In the U.K., volunteers add old and significant trees to The Ancient Tree Inventory, which has more than150,000 trees in its data set.
And just down the road from Toronto, the City of Mississauga has, since 2007, supported a Significant Tree Program, which allows residents to nominate any city-owned tree for recognition. So far, 50 trees have been recognized as a way to promote their community value.
Sandy Smith, professor of forestry at the University of Toronto, wants people to start looking at big old trees in the same way we look at big old buildings.
“Toronto’s Old City Hall is only still there because someone deemed it valuable,” she says.
“We need to do the same with our old and important trees. It seems obvious to say, but a 250- or 300-year-old oak tree takes a long, long, long time to get that big. We need to keep them, value them, protect them.” The Star wants to hear about the most significant trees in your neighbourhood. Send an email to email@example.com with a photo of your tree and the following information: Tree type (species), trunk circumference (measured at chest height), location of the tree and 150word explanation for why this tree deserves recognition. We may share your submission with readers in the Toronto Star and on thestar.com.
“These trees are the oldest, largest living things in Toronto,” says Eric Davies, a U of T researcher who is mapping the oldest and biggest trees in the city’s ravines.