Northwestern Ontario forests becoming more susceptible to frequent fires, insect damage, expert says

A researcher with the Canadian Forest Service says, while forest fires are a common and essential part of northwestern Ontario's boreal ecosystem, climate change will alter how frequently the region sees a "bad year."

The 2019 forest fire season has seen several large fires, some of which have forced evacuations of remote First Nations, burned very close to municipalities and damaged some power and telecommunications infrastructure.

"None of the individual fires that are actually occurring would be something that we would say are driven by climate change," said Joshua Johnston, a forest fire research scientist with the Canadian Forest Service. "Ten, 15 years ago, you might have had a bad year every four or five years."

"What we're seeing [now] is a trend towards having more frequent activities, so, basically, it's going to start to become more like an annual basis."

One thing that researchers have noticed which also accounts for the frequency with which fires can start, Johnston said, is the spread into the region of more insects that kill tress, making them more prone to catching fire.

"Bugs have killed off larger areas of forest," he said. "And when trees are dead, they're actually quite easy to burn, much more aggressive fire behaviour, typically."

"We also have seen a lot more storm damage, particularly in northwestern Ontario."

That storm damage, he said, knocks down trees, also killing them and drying them out, which also leads to more fuel that's ripe to burn more intensely in a fire.

"Frequently ... what I've noticed in the last few years of flying is many more burn scars [on the landscape] that are running into old burn scars," Johnston said. "So there's areas of forest that are re-burning year after year."

Johnston said that, itself, is not uncommon, but the frequency with which he said he now sees evidence of relatively new fires hitting older burns is on the rise. He added that northwestern Ontario's forests may be especially susceptible to the type of tree blowdown that heightens conditions for large fires.

"If you're fighting a fire and you know that, if it comes over the next hill, it's going to hit this stuff, that changes the game entirely," he said. "Because once it enters into it, it's extremely challenging to suppress."