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Across the Pacific Northwest, firs are dying in record numbers as beetles, extreme heat and fires test the trees’ endurance

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Mike Cruickshank of the Canadian Forest Service waters western redcedars in a drought experiment at the Pacific Forest Centre in Victoria. Here, researchers are testing how resilient different trees are to the effects of climate change, and the diseases and harsher conditions it will bring to Western Canada.Rafal Gerszak/The Globe and Mail

Fir trees in the Pacific Northwest have died off in record numbers in 2022 after three years of severe drought and heat waves, according to U.S. Forest Service researchers.

“We’re calling it Firmageddon,” said Danny DePinte, who runs the aerial survey program for Oregon and Washington State, in an interview. “Or, Fir Zombie Land.”

In some parts of Oregon, more than half of the fir trees have died, clearly visible as the evergreen conifer turns brick red. These mortality events are not unheard of, but this is twice as bad as any that has been recorded since the agency started tracking forest health in 1947.

The scale of the loss is alarming, especially when seen from the air.

“When I was flying over, it was the extent of it that set us back,” Mr. DePinte said. “You’d see it goes up one side of a mountain, and then it just keeps going.”

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Danny DePinte of the U.S. Forest Service has seen the creeping influence of 'Firmageddon' in the Pacific Northwest.U.S. Forest Service

The dead trees he is finding are mostly white fir and California red fir, but what is killing them similarly threatens Canadian forests – particularly in the British Columbia interior, where records for heat and drought were shattered in 2021 and 2022.

B.C.’s subalpine is already under attack: The Western balsam bark beetle has been slowly killing off fir at a rate of 1 per cent each year, impacting two million hectares of forests annually since 2014.

This is on top of the massive losses of forests to mountain pine beetle, and unprecedented forest fires.

Now, the province’s top forestry official is worried that recent droughts and heat waves will accelerate the die-off.

Subalpine fir, also known as balsam fir, is one of the most common tree species that grows in the interior of B.C. Like its other true fir cousins, it has a low tolerance to extreme heat and drought.

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Tree die-offs in the Pacific Northwest are the inevitable result when conditions are hotter and drier than native species can adapt to.U.S. Forest Service

In early December, the province established a stand-alone Ministry of Emergency Management and Climate Readiness to better prepare communities and infrastructure for environmental disasters. But the forest mortality event that Mr. DePinte and his colleagues have charted is a warning of how quickly an entire ecosystem can be altered. And while Canadian forest scientists are working on adaptation strategies, there are no quick fixes.

“Our forests certainly are a bit of a bellwether, in terms of how climate change is affecting not only British Columbia, but the planet,” said Shane Berg, B.C.’s Chief Forester. “There’s been an increase in the mortality in our subalpine fir because of the weather circumstances we’ve been experiencing over the last couple of summers.”

The province’s solution is to invite forestry companies to harvest where the bark beetle has taken hold. “There’s only one way that you can actively and aggressively remove them, and that is to salvage the trees,” Mr. Berg said. “We can draw the beetles into a more concentrated area using pheromones, which will put the populations into a more concentrated grouping for salvage harvests.”

Much of Canada’s 350 million hectares of forests are vulnerable to climate change, but some species will fare better than others. A 2020 report from the Canadian Council of Forest Ministers identifies the trees species that are at highest risk in the foreseeable future: In the boreal forest which stretches from the Yukon and northern B.C. to Newfoundland and Labrador, the most vulnerable are white and black spruce, aspen and conifers. In B.C.’s southern interior forests, both pine and fir are succumbing to wildfire, insects, drought and extreme weather.

The report warns that climate change is moving faster than most tree species can adapt: “Over the next several decades, the climate in Canadian forests will shift northward at a rate that will likely exceed the ability of individual tree species to migrate. While most tree species can migrate naturally up to a few hundred metres per year via seed dispersal, the climatic conditions in which each species thrives may move north by several thousand metres per year.”

While a mature forest can’t move fast, forests that are cut down or burned by wildfire can be replanted with species that are better adapted to the changing climate.

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Sophie White, right, is a geo-spatial field technician at the Pacific Forest Centre. She is placing western redcedar branches in blocks of alder that have been colonized by a fungus, part of an experiment to measure the spread of a condition called butt rot.

Mr. Cruikshank checks on some of the 2,487 seedlings in the butt-rot experiment. The fungus, Phellinus weirii, has been spreading from the alder to the redcedar and infesting the soil. Rafal Gerszak/The Globe and Mail

At the Canadian Forest Service’s Pacific Forest Centre, researchers are trying to find the toughest of each species, hoping to breed more resilient varieties that can be replanted for future forests.

Forest pathologist Mike Cruickshank studies the impact of stress on trees, and one of his test plots is a greenhouse where almost 3,000 young trees are subjected to drought conditions in order to find those with the right genetics for survival.

“We’re looking at drought tolerance. We’re also looking at insects and disease resistance. We’re just looking for the best and the toughest individuals we can find,” Mr. Cruickshank said.

The extreme weather over the past two years, according to his research, will result in more die-offs. It usually takes two years for the damage to show.

Trees can adapt to heat by drawing up moisture from the ground to cool themselves. Or they can survive droughts by putting on growth early in the spring and then switching to a dormant cycle. But not both at the same time.

“One of the big problems is heat plus drought. It’s not just drought, and it’s not just heat. It’s the two together. That’s really bad,” Mr. Cruickshank said. “And that’s what we are seeing.”

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