Scientists have discovered a record number of dead fir trees in Oregon, a worrying sign of how drought and the climate crisis are ravaging the American West.
A recent aerial survey revealed that more than a million acres of forest contain trees that have succumbed to stressors exacerbated by a multi-year drought. Images released by the US Forest Service show Oregon’s lush green expanses dotted with ominous red bands.
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“It’s mind-blowing,” said Daniel DePinte, Forest Service aerial survey program manager who led the agency’s aerial survey in the Pacific Northwest region, noting that this year has seen the rate of highest mortality for firs in this region in history. These evergreen conifers are less able to survive drought conditions than other hardier trees that border landscapes.
He and his colleagues scanned the slopes from planes several times between June and October, detailing the devastation on digital maps. During this time, it became clear that this year would be unlike anything he had seen before. The report is still being finalized, but dead trees have been spotted in areas of Oregon’s 1.1 million acres of forest. Scientists have taken to nicknaming it “firmageddon”.
“The size of this is massive,” DePinte said. “A lot of people think climate change is only impacting the ice caps or a low-lying island, but it’s actually impacting here in our backyard,” he added. . “If this drought continues as climate change continues and we continue to ignore what nature is showing us around the world, it doesn’t bode well.”
Continued drought, coupled with recent extreme heat, has left more vulnerable trees like fir trees struggling to adapt. As the cascading effects of the climate crisis unfold, ecosystems are expected to change. The loss of these trees is a sign that the forests may already be beginning to change.
“It will be a different forest with a different feel and it will happen across the landscape as nature dictates,” DePinte said. “Nature says there just isn’t enough to support fir trees, and they will be wiped out of these areas over time.”
Scientists expected to see signs of stress in the forests, but the suddenness of the spike in mortality was alarming. Prior to this year, the largest area where dead trees were recorded in Oregon was in 1952, where mass kills were spotted on approximately 550,000 acres.
“It’s not surprising that this is happening, but to see such a spike in the space of a year – it’s concerning,” said Christine Buhl, a forest entomologist with the Oregon Department of Forestry. The underlying conditions that caused the spike – record high temperatures and record rainfall – had a cumulative effect on the forest due to timing, duration and frequency.
“Hot drought is a double whammy for a tree,” she said, explaining that the roots of drought-stressed trees die, making it more difficult for them to recover even when water is available. A prolonged lack of moisture, especially during growing seasons when rainfall was once again abundant, also harms a tree’s vascular tissues which are used by the tree to draw up water.
“It’s a bit like trying to suck a milkshake through a straw but there’s a hole in the straw,” Buhl explained.
Rebuilding these essential tissues takes time and also requires resources. When conditions persist for longer periods, some trees are not able to cope. Stressed trees are also more susceptible to other stressors, including insect infestations and disease. “Sometimes you’ll see trees die years after a major water stress,” she said, “because they just tried to hang on.”
The loss of these trees can alter other forest ecosystems. The flood of heat and light formerly protected by a thick canopy can increase the temperature of streams or make room for invasive species formerly protected by shade. Some species will thrive on change. Bees that nest in the forest floor, Buhl said, benefit from the burst of sunlight that also helps flowering plants bloom. But others will perish.
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The effects are not limited to Oregon, and scientists have observed a similar situation – if much less severe – mass fir mortality in Washington State, although fewer of these types of trees are growing there.
The death of trees also increases other risks, such as forest fires. “Long periods of drought and extreme heat can weaken trees and make them more susceptible to things like insects and pests,” said Washington Department of Natural Resources spokesman Will Rubin. “This overgrown dry, dead wood is becoming more likely to fuel these fast-moving, heat-intensive wildfires that blanket the west in smoke.”
As heat waves and drought conditions worsen in the American West, landscape managers are looking for ways to adapt and increase forest resilience, including through proven treatments such as burning. directed that helps the earth heal and protects against catastrophic fires.
“We are trying to help return our forests to this historically resilient state, while managing and understanding the impacts of these severe weather events, as climate science shows they are more likely to occur more often,” said Rubin said.
When it comes to mortality, researchers are trying to embrace change. Dead trees cannot be replanted. “You have to get used to it. We’re not going to see certain species in the same places that we hoped for in the past,” Buhl said. She points out that understanding where the climate will be in the coming decades can help them anticipate problems. “If we can prepare ourselves and know that there is going to be a change in the way things look,” she said, “we will be much better off.”