Seven of the 10 fastest-growing fires were in Canada in 2023, the year of the country’s worst fire season
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New research suggests that fast-moving wildfires, such as the Bald Ridge blaze near Summerland that forced recent evacuations, are burning bigger and leaving forests less able to grow back to their pre-burn state.
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The study, published in Science Advances, analyzed nearly 3,500 fires across Canada and the western U.S. between 2012 and 2023. Researchers used satellite data to track how quickly fires spread each day. They found the fastest-moving fires burned more severely, killed more trees, and made it more difficult for forests to regenerate.
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“It’s not necessarily incredibly surprising that fast-moving fires are responsible for the largest area burned. But we now also show that they have pretty outsized ecological impacts as well,” said Ellen Whitman, a forest researcher with the Canadian Forest Service at Natural Resources Canada and one of the study authors.
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Those impacts can range from changing the tree makeup of a forest, “something we have been seeing quite a lot in the northwestern boreal,” Whitman said, to no tree regeneration at all, a result Whitman called “pretty extreme.”
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Some tree species can regrow from seeds even if the parent is killed by fire, but others need seeds from live trees nearby. Fast-moving fires can leave large patches of forest with no living trees and no way to regrow the way they were before.
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The pattern was most pronounced in the Western Cordillera ecosystem, which covers much of B.C.’s central and southern interior and includes the Bald Range wildfire in Summerland, which has forced thousands from their homes. That fire, mapped at more than 212 square kilometres as of Monday morning, continues to spread but is moving away from communities, according to fire officials. Some residents have been allowed to return to the community, though evacuation alerts remain in effect.
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“The Western Cordillera is also likely to have experienced the greatest effects of ongoing modern fire suppression,” the study’s authors wrote, noting the ecoregion accounted for more of the area burned, more fires and more fast-spreading events than any other region studied.
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Whitman said there is strong evidence that historically there were frequent, low-intensity fires in the ecoregion that cleared small trees and other fuels, limiting the chance of the type of fast-burning fires B.C. is now experiencing.
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“That was generally associated with Indigenous cultural burning,” she said.
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Whitman said climate change and a shift in long-term precipitation patterns in B.C. have also contributed to the speed and intensity of wildfires.
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“Fire size and spread rates are very much associated with fire weather, and fire weather is what’s changing the most dramatically or the most rapidly as a result of climate change,” Whitman said.
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“In these incidents where we have the fastest moving fires … we do see a greater ecological impact, and we would expect that again to hold true going forward,” she said.
