Old growth forests with just modest exposure to fire are now most at risk for severe wildfires across the region. That’s according to a new analysis from scientists with Oregon State University and the USDA Forest Service Research & Development.
Researchers say 75% of the Pacific Northwest’s forests that historically saw low and mixed severity fires are highly vulnerable to devastating blazes today.
Part of this vulnerability came after Indigenous people were driven out, and therefore unable to practice controlled burns to reduce slash and pests, as well as rejuvenate the landscape.
“There's a reawakening of that knowledge and movement forward in terms of indigenous fire stewardship,” said OSU fire ecologist and forestry professor Meg Krawchuk. “But there are so many parts of the landscape that are not ready to receive fire well, and that require additional care and tending to bring back fire to our landscape."
In its release, OSU said an aggressive campaign of extinguishing fires “became federal policy following the Great Fire of 1910, which destroyed several towns and burned an area roughly the size of Connecticut across forests in Idaho, Montana, Washington and British Columbia.
“Prior to fire exclusion, frequent low- and mixed-severity fires had played a key role in maintaining the forest ecosystems of the western United States. Since then, older forests and trees have seen major structural shifts as shade-tolerant and fire-intolerant species have moved in.”
The release also said through the 20th century, “mature and old-growth forests on national forests saw major declines because of logging. In recent years, wildfire has replaced logging as the largest threat, and since 2000, federal lands have seen a net loss of 2.6 million acres of mature forest and 700,000 acres of old-growth forest. Those acres were designated for multiple uses including recreation, timber production and wildlife habitat, providing important ecosystem services.”
Pockets of landscape less susceptible to crown fire called fire refugia may help buffer these sensitive forest areas, and reduce severe fire risk by up to 20%.
“Fire refugia are places that have stand conditions and are sitting in the topographic template, or in topographic settings that can take care of themselves when it comes to receiving fire well,” said Krawchuk.
The researchers studied federally-owned forests comprising 24 million acres across Oregon, Washington and northern California. Roughly 7 million acres of that same area contained mature or old-growth forest, with nearly 2 million acres in fire refugia area. The researchers also deemed the Klamath Mountains a “hotspot” for wildfire exposure and potential carbon emissions.
“As a fire ecologist and as people in our region who are increasingly living with fire, we know we need to learn to coexist with fire in ways that are socially and ecologically just,” Krawchuk told KLCC. “And this study is one part of that path.”
The full analysis can be found in Natural Hazards. Other contributors included Bruno Aparicio, a postdoctoral researcher in Krawchuk’s group within OSU’s Department of Forest Ecosystems and Society; and Michelle Day, Raymond Davis and Rachel Houtman of the Forest Service, which provided funding for the research.
Copyright 2026, KLCC.
