Derecho has changed Ottawa’s canopy forever: ‘This is worse than the tornado’

Storms typically destroy spruce and pine, with their shallower roots, not the hardwoods, not the large maples and oaks that make up a neighborhood

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Ottawa arborist Ryan Burns expected trees to fall over the weekend. He saw a splash of deep red sweep across the weather radar on Saturday and got ready for calls from homeowners. But what has shocked him in the 48 hours since that violent series of thunderstorms over Southern Ontario and Quebec is the kind of trees that fell.

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Storms typically destroy spruce and pine, with their shallower root systems, not the hardwoods, not the large maples, oaks, and poplars that make up a neighborhood’s character.

But Saturday’s thunderstorm was different. Environment Canada clocked winds in excess of 80 miles per hour — the kind that can rip shingles off roofs, rip metal siding off buildings and, apparently, split mature hardwoods in half or pull them completely off the earth. Burns has seen old maple trees knocking on their sides, their roots like disconnected cords.
“That’s not happening,” he said Monday. “The Ottawa landscape will never be the same.”

Meteorologists are calling the storm a derecho — a series of thunderstorms that started in southwestern Ontario and moved east through Toronto into the Ottawa Valley, hitting each region in a brief but intense eruption that killed a total of 10 people, most of them through fallen trees, and left without power for hundreds of thousands of days. Experts are still scanning the damage for signs of rotating winds to determine if tornadoes have occurred in the derecho.

Environment Canadian meteorologist Gerald Cheng said he’s seen derechos in Ontario before, but not one that has engulfed a series of densely populated population centers, with so much death and destruction in its wake.

“It’s rare,” he said. “I haven’t seen it in my career.”

Southern Ottawa is one of two “concern areas” where tornadoes occurred on Saturday, Cheng said. The city’s tree population has already been culled by a tornado that swept through the region in 2018.

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Burns cut trees in the aftermath of the 2018 tornado and he was working this weekend. “This is worse than the tornado,” he said. “The number of trees that have fallen, the amount of old growth that has come down — we didn’t have those trees to lose.”

On top of the trees lost by the 2018 tornado, Ottawa has faced a plague of emerald ash borer — an invasive beetle that has killed millions of ash trees in Canada. The ash borer has distorted the appearance of residential streets in Ottawa, where ash trees made up about a quarter of the forest canopy, said Councilor Scott Moffatt.

“The last thing we want is to lose mature trees, and that’s clearly what happened this weekend,” said Moffatt, chair of the city’s environmental committee. “I have seen many large, healthy mature trees that were completely uprooted. And they are gone forever. You don’t replace it overnight.”

Driving through town over the weekend, Burns kept seeing piles of bushes along the road. He was responding to a call that an 85-foot pine tree fell through the roof of a bungalow in Nepean, west of the city.

“Every other house you look at, there are trees around it,” he said. And for each of those homes, it takes decades for those front yards or back yards to get their old tree back.

That’s years of lost shade in the summer, thinner piles of leaves in the fall. But for the people who have lived there, it also means that the tree they grew up with, the one they climbed, the one whose chestnut trees pricked their bare feet on sunny days, that prominent backdrop to their memories, it’s gone.

National Post, with additional coverage by The Canadian Press

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