We thought we were saving the planet, but we were planting a time bomb

At first, it looked like a sunset. It was just after five o’clock in June. I was running in Toronto beside Lake Ontario when I stopped to glance at my watch and noticed that the sky was no longer blue but a rusted orange. It took only a few breaths to realize the bonfire smell in the air was the drifting product of faraway wildfires.

It’s quite possible you had a similar experience this summer: The plumes of gases and soot from Quebec and northern Ontario that plagued Canada also blanketed the American Midwest and East Coast. But as I watched the sun burn a hole in the horizon, I had an additional realization: Thirty years ago, I did something that probably helped fill the sky with smoke.

In the early 1990s, I worked as a tree planter in northern Ontario. This was a common — if notoriously grueling — rite of passage for Canadian university students, since it allowed you to make good money while spending a few months outdoors with other like-minded young people. I was driven in part by the idealistic view that planting a tree was always going to be better than not planting one.

In retrospect, this wasn’t true. Forestry experts understand that a monoculture of trees — like the black spruce saplings we were planting, six feet apart in neat rows — has made wildfires more likely, and much worse when they occur.

At the time, I didn’t fully understand how the tree-planting industry worked — all I knew was that we were planting in clear cuts, areas where forests had already been harvested en masse by a logging company. In Ontario, the responsibility for woodland regeneration had largely been transferred to the forestry businesses that held the logging contracts; as part of those contracts, they could do things like cut more trees or reduce their government fees if they invested in reforestation. So after my school term ended I moved, along with a few dozen eager summer planters, to a bush camp outside of Hearst, roughly halfway between Toronto and James Bay.

Our job was to dig holes and plant black spruce seedlings. I carried three bags of them, one on each hip and one in the back. In steel-toe boots, I broke through shallow puddles that were covered with translucent films of ice, wallowed through mud, and crawled over tree stumps. I had duct tape wrapped around each finger and on both heels to cover up the blisters. When I asked someone why our saplings were always spaced six feet apart, the answer came back with a smirk — so the cutting shears would fit between the grown trunks when they got cut down again.

Despite the cynicism, our general mood was triumphant — we were working hard and replenishing the earth. Perhaps the ethos was best captured by Charlotte Gill in “Eating Dirt,” her book about tree planting: “We didn’t make millions, and we didn’t cure AIDS. But at least a thousand new trees are breathing.” The Canadian actor Will Arnett spent a summer planting trees, of which he has said, “There’s a sense of giving back, and a sense of obligation” to “create something bigger than yourself.”

Through black flies, mosquitoes, blisters and bears, we worked for pay of roughly 9 to 11 cents per tree. At my peak, I planted a few thousand saplings a day. After camp costs and taxes were deducted, I might clear $6,000 in a summer. Rumors abounded of tireless super-planters who could earn up to $10,000 in a couple of backbreaking months.

Sometimes the work could be miserable. One morning, I nearly quit. In an attempt to cheer me up, my friend launched himself out of the van transporting us. “Let’s go make a forest!” he shouted. His laugh was just enough to keep me going.

Much later, I learned that the trees we were planting, black spruce, are so combustible that firefighters call them “gas on a stick.” The trees evolved to burn: They have flammable sap and their resin-filled cones open up when heated to drop seeds into charred soil. In “Fire Weather: A True Story From a Hotter World,” an investigation of the devastating wildfire in 2016 in Fort McMurray, Alberta, John Vaillant laid out how climate change had turned some forests into combustible time bombs, where “drought conditions, noonday heat and a stiff wind” can turn a black spruce tree into “something closer to a blowtorch.”

In a naturally occurring forest, black spruce is often found in a mix with trees like aspen and poplar, which are full of moisture and provide a natural resistance to fire. But as a report by the Forest Practices Board of British Columbia pointed out, “Large homogeneous patches of forest are more likely to lead to large and severe wildfires.”

The dangerous mistake we were making gets to the heart of what people often get wrong about environmental stewardship: the notion that, no matter how rapacious or careless we are, we can always dig or plant our way out through sweat, pluck and industry. Rather than leaving a forest intact, we clear-cut it, then replant a new one. My troupe of planters thought we were making things better. I spent this summer watching that youthful idealism literally going up in smoke.

As I stood by Lake Ontario looking at the orange sky, I started to choke and rubbed my scratchy eyes. I saw it clearly then: The sky was no longer blue and planting a tree wasn’t intrinsically good.

An article by Saul Elbein for National Geographic attempted to pinpoint the cause of the fires that had threatened Fort McMurray, prompting the evacuation of over 80,000 people. As it turned out, around 1980 a government-driven project changed the landscape in that area by planting trees. They were “pines in lines”: rows of carefully spaced black spruce. A study Mr. Elbein referred to found that in the years leading up to the Fort McMurray fire, these trees soaked up the groundwater, and their wide canopies caused the existing peat moss to be replaced by a drier kind of moss, which was like spreading “kindling in the place of fire retardant,” as Mr. Elbein wrote. When the fire started, the trees had become storehouses of fuel.

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