The densest 100 metres — Arlington Avenue and the city's most-treed block

If you grid the City of Toronto's 689,013 street trees into 100-metre × 100-metre cells, drop everything that's actually a park boulevard or a parkway, and take the residential winner — the densest single 100-metre block in the city — you land on a stretch of Arlington Avenue between Winnett Avenue and Rushton Road, in Humewood-Cedarvale. 128 catalogued city-owned street trees in 100 metres of north-south block. About one tree every 1.5 metres, both sides of the street, in continuous succession.

What's more interesting than the count, though, is the species mix.

What's on the block

That top row is the story. Thirty-four red oaks on a single residential block. Add the swamp white oak and the English pyramidal oak (a Quercus cultivar, also planted heavily in recent years) and you're at 51 oaks on one block — almost 40% of every tree.

This is unusual. Citywide, the dominant maple-and-honey-locust mix produces the typical residential canopy: a row of Norway maples on one boulevard, a row of honey locusts on the other, the occasional Freeman maple. Oaks are scattered, present, but rarely the dominant species on a residential block. They grow slowly, they cost more to install, they produce acorns most homeowners don't want — and the post-EAB native-push that put them in the city's planting program in volume only really started 15 to 20 years ago.

So what you're seeing on Arlington is the output of that program. Probably planted somewhere between 2008 and 2018, in a continuous wave, on both sides of one block, by one or two crews working a city contract. The trees are still young — average trunk diameter on the block is 26 centimetres, which for red oak suggests roughly 30–40 years old (red oak is a slow grower). The canopy hasn't closed yet. In another twenty years it will be one of the most ecologically rich short blocks in Toronto.

Why oaks here, specifically

Humewood-Cedarvale sits on the upper edge of the old Davenport sandbar — the geological feature that runs roughly under St Clair Avenue and marks the shoreline of Lake Iroquois twelve thousand years ago. The neighbourhood was platted around 1910, on what was then the edge of the city's expansion north of St Clair. Many of the original boulevard trees would have been American elms, killed off by Dutch elm disease in the 1960s and 70s. The remaining mature canopy on Arlington today is a sparse mix of survivors and 1970s honey-locust replacements.

What I think happened — though the dataset doesn't tell us this directly — is that one of the recent municipal repaving cycles cleared the old boulevards on this block, and the post-2010 city planting program filled the gaps with native oak. Red oak in particular is now Toronto's flagship native plant: it tolerates urban soil, supports 534 species of native Lepidoptera per tree, and produces brilliant red fall colour that holds into November. The pyramidal English oak is its narrow-form cousin, planted where the boulevard is too tight for a standard crown.

The Manitoba maples — 15 of them on the block — are the older cohort, easy to spot because Manitoba maple is a pioneer species that volunteer-grows in any disturbed urban soil and the city catalogues the ones that establish themselves. They're the unintentional scaffolding around the deliberate plantings.

Density at scale

For comparison, here is the opposite end of the city: a 100-metre cell on Lake Shore Boulevard West in Fort York–Liberty Village, near the foot of Strachan. One tree per 100-metre cell on the south side of the road; three on the north side. A Kentucky coffeetree the city installed in 2019 strapped to a stake. Two honey locusts in raised concrete planters at the base of a 32-storey tower.

The same 100-metre window. 128 trees vs. 4. A ratio of 32 to 1.

This isn't a wealth gap. Liberty Village's median household income is comparable to Humewood-Cedarvale's. It's a street-form gap — a fifteen-metre-wide 1910 residential street with two-metre boulevards both sides versus a forty-metre-wide 2008 collector road with no boulevard at all. The trees fit where the streets allow them to fit, and the streets were drawn before or after the car.

Walking it

If you want to see this block: get to St Clair West station, walk west on St Clair to Winnett, turn north onto Arlington. The first block is the dense one. Walk slowly. The young red oaks are easy to identify in summer — characteristically lobed leaves, sharply pointed lobes, dark green in summer turning red in October. In winter you can pick them out by the slate-grey furrowed bark, distinct from the smoother grey-black of nearby maples.

Continue north and the density falls off — the next blocks of Arlington are normal residential street, denser than the city average but not record-setting. The unusual concentration is just that one stretch.

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