What the trees know
On a small residential street in west-end Toronto, on the boulevard in front of a house on West Lodge Avenue, stands an American elm with a trunk 190 centimetres thick. It is probably a hundred and twenty years old. For much of that time, its species was the defining tree of Toronto — the vase-shaped silhouette that arched over University Avenue and St. Clair and Bloor, forming the dappled green tunnel that gave this city its "city in a forest" reputation a century before we turned the phrase into a slogan.
Then, in the 1960s and 70s, Dutch elm disease arrived and took almost all of them. What happened is that a fungus, imported from Europe on infected wood, found in the American elm a host with no evolved resistance. The trees died, one by one, across Ontario. Most of the great elm avenues of Toronto — the ones that made us famous — do not exist anymore. The trees you walk under on those same streets today are maples and honey locusts, planted after.
But the elm on West Lodge is still there. A hundred and twenty years old. It has outlived an entire pandemic of its own species. It watched most of its siblings die around it. The city is now keeping it alive with periodic fungicide injections, which cost the treasury more than the tree is "worth" by any utilitarian accounting. Why do we do it? Because the elm itself is older than the idea of fungicide. It was here before the argument. It will, in all likelihood, be here after the current argument is forgotten.
The root system
The most famous tree in the world, if you define "tree" carefully, is called Pando. It lives in Utah. It is a quaking aspen — Populus tremuloides — and by the standard of what we normally consider an organism, it's actually forty-seven thousand trees. But they all share a single root system. Every "tree" on the 43-hectare plot is genetically identical, shoots of the same underground being. It is, by mass, the heaviest known organism on Earth, and by age, older than the last ice age.
An aspen stand looks, from a distance, like a collection of individuals. If you cut any one of them down, you are pruning a hair on something much larger. The tree is not the thing. The thing is underground, and it is one.
Toronto has aspens. Not Pando-sized ones, but 3,000 or so small groves of quaking aspen and bigtooth aspen, mostly in ravines and roadside wild patches. When you see them, silver-barked and fluttering in the slightest wind — the name tremuloides literally means "trembling" — you are looking at what is almost certainly a single organism pretending to be many.
The metaphor is the metaphor you expect. We are more connected than we look. The "individuals" are the part of the structure that briefly rises above the soil to be visible. The real continuity is elsewhere. Suzanne Simard's work on mycorrhizal networks in Douglas fir forests has formalized something aspens have always been doing plainly: trees share. Carbon, water, nitrogen, alarm signals, even offspring-recognition — routed through an underground fungal network that connects the roots of dozens of species across the forest floor. The "wood wide web," as it got branded.
None of this is particularly visible from the sidewalk. A maple in front of your house looks self-sufficient. Underneath it, the maple is in conversation with the elm three doors down, the linden on the cross street, a dozen species of soil bacteria, and a fungal network whose extent nobody has mapped. The tree you see is the hand the organism has extended above the surface to breathe.
Listen. Every tree is an echo of the forest.
The long view
In a park in the high end of the Annex, at 179 Spadina Road, there is a bur oak 183 centimetres thick. A 180-centimetre bur oak in Toronto is roughly a hundred and fifty years old, give or take. Which means it is older than the Annex itself. It was, most likely, standing when the fields it shaded got sold off to speculators in the 1880s, and it stayed standing while those fields became lots, and those lots became houses, and those houses became the neighbourhood it is now quietly lining. It was a tree before the house. The house will not outlast the tree.
This is easy to forget. The municipal street grid feels permanent. Roads have names and histories and plaques. Buildings have architectural periods you can place. Cars, streetcars, transit, zoning, the shape of the blocks — these all feel like the skeleton of the city, the given thing against which everything else is measured. But most of it is younger than its trees.
When a city plants a street tree today — a honey locust, say, on a rebuilt boulevard in Scarborough — it is committing to a kind of infrastructure that will be in active service in 2125. Nothing else the municipal budget pays for has that horizon. A water pipe will be replaced in 80 years. A road will be repaved in 20. A bylaw will be rewritten in 10. The tree will, if lucky, still be there. It will, by then, have been maintained by four generations of urban-forestry staff, none of whom worked for each other, all of whom inherited the tree from their predecessors and handed it to their successors. The tree is the civic project that outruns its own project managers.
The people who planted the 183-cm bur oak on Spadina did not know us. They did not think about us. They probably did not think about anyone. They planted the tree, most likely, because a tree was what the corner of that farm lot deserved. We inherited it without their intent. We will leave it — or fail to leave it — without the intent of anyone in 2150.
The witnesses
There is exactly one pawpaw tree on Toronto's street-tree inventory, at 39 Macdonell Avenue in Roncesvalles. Pawpaw is a native Carolinian species; it makes a custard-fleshed fruit that tastes vaguely tropical and rots within three days of ripening. There is one of them on a boulevard in west-end Toronto. The tree does not know this. It is just doing what pawpaws do. From its perspective, the rest of its species is somewhere else and it doesn't matter where. It grows, flowers, makes fruit most years, drops leaves in fall, goes dormant, repeats.
I think a lot about these one-of-ones. The pawpaw. The bald cypress at 25 Cavehill Crescent (a southern swamp tree surviving as a Scarborough street tree, a small climate-adaptation triumph nobody campaigned for). The Magnolia 'Yellow Bird' at 36 Lissom Crescent, blooming butter-yellow every May. They are each the entire population of their species in Toronto's boulevard inventory, and they are each doing their own small work of just being the thing they are. If they die, the species count drops to zero. Someone might not notice for a year, maybe two.
Or consider the other end. 69,347 Norway maples, as of the last count. A species we no longer plant because we came to regret the monoculture. They are collectively 10% of the whole inventory, collectively three-and-a-half million dollars of ecosystem services a year, collectively the biggest mistake in the history of Toronto's urban forestry program. Also they are old now, and shade the same streets my grandparents walked on, and my kids might walk on, after I'm gone. The mistake is also a kind of inheritance. The tree is not moral. It is just a Norway maple doing what Norway maples do.
Trees are present for everything the city does, but they don't participate. They don't vote. They don't move. They don't protest. They don't argue with zoning. They are a stationary population of silent, long-lived, metabolically active presences that line our streets and absorb weather and water and carbon and bear whatever happens. The elm survives its pandemic. The oak watches the Annex get built around it. The pawpaw in Roncesvalles does its small Carolinian thing in a climate zone it just barely tolerates. They accumulate. They stay.
The cataloguing
This site is, in one view, just a search tool with some blog posts attached. In another view, it is a small civic gesture: an attempt to take 689,013 trees, each of which is a quiet long-lived thing the city has committed itself to, and make it slightly easier for any one of us to know which one of them is in front of our own house. That is a small gesture. The trees themselves don't need it. I needed it.
What the trees know is easy to state and impossible to internalize at a personal level: they will outlast us, they are connected below the ground in ways we mostly can't see, and they will carry forward whatever we plant into a future we won't be in. The rest of the posts on this site argue with data. This one is just the feeling underneath the argument.
If you have a tree in front of your house, go find out its species sometime. It was planted there by someone who will not meet you. It may outlast whatever else is on your block. Knowing its name costs nothing and is a small kind of thanks for an infrastructure we mostly take for granted.