Like many city-dwellers, I’ve been trying to get out of the city. High-season car-rental fees have begun to seem reasonable, if they mean getting to a place where I’m surrounded by green things that absorb heat, instead of concrete that throws it back at me.

I went to the Kawartha Highlands, where regal pines provided sweet relief, and Muskoka, where I hung my swimming towel on the outstretched arm of a maple. That’s what summer requires, I thought, a little fresh air, provided by trees.

For some reason, it didn’t occur to me that I see trees everyday, one in particular – it lives in the laneway behind my house.

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I tend to look away from it, actually, because it’s not that pretty. There is a serious snarl of wires among the poor thing’s branches. A big limb that used to block sun from my yard was cut off last year by a telecom company needing to install yet another box and tangle, while a particularly tight cord is strangling another branch, the topmost leaves of which no longer come in.

Its roots are rumpled under our interlocking brick and my husband chipped away some bark last year to install our back fence. I felt like the tree couldn’t be enjoying its city life much, and I felt a bit guilty about it, so I averted my gaze.

Ignoring urban trees isn’t a smart move for urbanites, at least those concerned with either weather or breathing. Trees don’t just produce oxygen, but sequester carbon. They intercept rain runoff, which is particularly needed in Toronto right now, where a series of heavy storms in the past couple of weeks has repeatedly flooded the Don Valley Parkway and the subway and caused the roof to leak in the hallway outside the mayor’s office.

Trees provide shade that can significantly reduce air-conditioning use (and bills), and serve as homes for the animals that are also an essential part of our ecosystem, even if they irritatingly eat our tomatoes. But “tree literacy,” as arborist Todd Irvine calls it, isn’t something many city people are versed in, and so we take them for granted.

Mr. Irvine is a friend-of-a-friend who works with Bruce Tree Experts, and also teaches ecology at the University of Toronto. I invited him over to diagnose my tree, even though I was afraid of what he’d tell me. I thought it was going to be a lot worse from your description,” he said. Phew, apparently it’s very healthy.

The flaky bark that worried me is supposed to be like that: It’s actually called exfoliating bark. I shouldn’t have been comparing it to the darker, smoother bark of my neighbour’s tree, which is a Norway maple. Mine is a silver maple, between 40 to 50 years old, younger than the utility pole it’s butted up against, the source of its wire troubles.

The wire girdling the dying limb is no longer connected to anything, so Mr. Irvine advised us to snip it off. He gave my husband a stern look for interfering with the bark – “this is a wound, it won’t grow back,” he said, touching the smooth spot we made – and said that being an arborist in Toronto is like being a vet constantly surrounded by injured animals. In his own yard, he’s providing what he hopes isn’t palliative care for an ash tree: there used to be 800,000 of them in the city, but most have died from an insect infestation.

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That’s a big chunk of the city’s tree canopy, which is made up of approximately 10 million trees, about 40 per cent of them city-owned. The rest are on private property, susceptible to individual whims. People tell Mr. Irvine that trees are messy, or worry that they’re hard to maintain.

They’re afraid of injury or destruction during storms, which is both fair and ironic, since planting trees is one of the simplest ways to forestall climate change. They come up with legions of reasons it’s better to pull living things out of their yard and replace them with hard surfaces, which increase flood risk and interfere with the root systems of other trees nearby.

“I always say arboriculture is as much psychology and sociology as it is ecology,” Mr. Irvine said. What might help is to stop considering trees nice accessories to urban life and instead realize they’re essential infrastructure for human existence.

For years, the city has been trying to get Torontonians to plant more trees: The goal is to increase the canopy from its current 27 per cent to 40 per cent in the next half-century. That’s great, but a skinny new tree can’t do as much work as a mature one. We also need to take care of the ones we already have, to make sure they have enough soft space and air to grow and thrive.

Trees do a lot for us, and it’s time we did more for them.