Summary:
In conifer forests across western North America, the speed at which a wildfire spreads is associated with how severely the landscape burns and how much capacity remains for trees to regenerate afterward. Researchers assessed 3,499 fires in Canada and the western US from 2012 to 2023, covering more than 33,000 daily fire-growth events.
The analysis, reported in Science Advances, showed that higher fire spread rates were associated with greater burn severity and a larger proportion of forest experiencing high-severity fire. Rapidly spreading fires also left burned areas farther from surviving live trees, which can serve as seed sources for forest regeneration.
Reduced tree cover and greater separation from seed sources can make recovery more difficult and increase the potential for long-term vegetation change, including shifts away from forest in some locations. The researchers warn that more frequent extreme fire spread under longer fire seasons and increasingly fire-conducive weather could expand these ecological effects, strengthening the case for management and postfire restoration aimed at sustaining forest ecosystem functions.
Read also: Global CO₂ emissions from forest fires surge by 60%, warn scientists
— Press Release —
Fast-moving wildfires leave forests less able to recover, study finds
The severe, drought-fueled fires now burning across much of the American West and Canada may be scorching forests so thoroughly that they cannot recover to the forests they once were, new research shows. A study by Colorado State University, Western Colorado University and others has found that the fastest-moving forest fires not only burn more area, but burn it more severely, leaving fewer surviving trees to reseed the landscape and opening the door to different species and vegetation types.
The study, published in Science Advances, examined nearly 3,500 wildfires that burned in conifer forests across western North America between 2012 and 2023. The findings suggest that as conditions become more favorable for fast fire growth, forests may be increasingly pushed toward long-term ecological change rather than recovery.
“People often focus on the size of a wildfire because that’s what makes headlines,” said lead author and Western professor Jonathan Coop. “But how fires burn is as important as how much they burn. In forests, fire speed not only increases acres burned but also leads to outsized impacts to each of those acres.”
The researchers, including Camille Stevens-Rumann, director of the Colorado Forest Restoration Institute and a CSU professor of forest and rangeland stewardship, as well as others from UC Berkley, the U.S. Forest Service, the Canadian Forest Service and elsewhere, analyzed more than 33,000 individual daily wildfire spread events for the study. They compared how quickly fires moved with what remained after they burned.
They found that as fire spread rates increased, so did the amount of forest experiencing near-total tree mortality and the distance to surviving trees capable of reseeding the burned area. Many western tree species rely on nearby living trees to naturally repopulate burned areas.
Read also: Canada tries to adapt to a future of wildfires
“When severe fires leave large expanses without seed trees, the forest has a harder time recovering and, in some places, may not recover as a forest at all,” Stevens-Rumann said.
Instead, those landscapes may gradually transition to shrublands, grasslands or other vegetation better suited to warmer, drier conditions.
“The story isn’t just we’re getting bigger fires,” Coop said. “It’s that the kinds of fires we’re seeing today are creating fundamentally different landscape outcomes.”
The findings build on years of research examining how wildfire behavior is changing across western North America. Previous studies by Coop and his colleagues have shown that a relatively small number of extreme fire-spread events account for a disproportionate share of the total area burned each year and that changing climate conditions are increasing the likelihood of those extreme events.
This latest research shows that faster fires also reduce forests’ capacity to recover.
The findings also point toward practical strategies for helping forests adapt to a future of more extreme wildfires. The researchers highlight the importance of active forest management, such as thinning, prescribed fire and managing fire burning under non-extreme conditions, and of expanding efforts to restore forests after they burn.
However, accelerated warming will pose growing challenges to traditional forest management and growing risks to forest ecosystems as long as climate change continues.
“Wildfire has always been part of western forests,” Coop said. “What’s changing is the pace and impacts of fires. As extreme events become more common in a hotter, drier climate, we can’t count on forests to persist or grow back the way they have in the past.”
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Adapted from a news release by Western Colorado University.
Journal Reference:
Jonathan D. Coop et al., ‘Faster, bigger, more severe: Extreme wildfire spread sets the stage for forest ecosystem change in western and boreal North America’, Science Advances 12 (33): eaeg5802 (2026). DOI: 10.1126/sciadv.aeg5802
Article Source:
Press Release/Material by Jayme DeLoss | Colorado State University (CSU)
Featured image credit: Luke Miller | Pexels
