Prescribed Fire–Overrated Strategy

The Deschutes National Forest plans to ramp up prescribed burns across Central Oregon. However, the Forest Service exaggerates the presumed benefits of prescribed burning and ignores the problems.

A forest service employee lighting a prescribed fire on the Deschutes NF, OR. Photo George Wuerthner

One of the most important issues is that  most wildfires never encounter a fuel reduction, whether from thinning or prescribed burns. So, even if prescribed burns were effective, fires seldom occur in treated areas.

Unless burns are repeated frequently, within a few years, the fine fuels like grasses, pine needles, and shrubs usually return to pre-burn conditions. Photo George Wuerthner

Second, the burn must be repeated every few years—forever to be effective. By removing competing vegetation, plant regrowth is rapid. Often, within a few years, there is as much or, in some cases, even more burnable biomass than before any prescribed burn.

For example, one study conducted in California Sierra Nevada found that within two years after a spring season burn, the herbaceous vegetation in the prescribed burn area did not differ from non-burned controls.

This area was burned just two years prior, and already the regrowth of grass has largely negated any benefical effect on potential fire spread. Photo George Wuerthner

Creating more fine fuels like grasses, shrubs, and small trees exacerbates the spread of fire.

Smoke from prescribed fire poses a health risk. Photo George Wuerthner

Thus the effectiveness of a prescribed burn depends on the time since its ignition, and the regrowth of plant material quickly negates its usefulness. Hence, communities will experience the harmful effects of smoke every year, even though the likelihood of a significant fire and attendant smoke may not occur in that locality for years.

The severity of wldfire and the acreage burned can vary greatlly. In recent years tens of thousands of acres were charred. Photo George Wuerthner

For instance, in 2023, the Deschutes NF initiated prescribed burns that charred  8,950 acres.

Oaks at Cascade Siskiyou NM in Oregon. Despite Indian burning, there were numerous large blazes in the region prior to Euro American settlement, suggesting that Indian blazes did not preclude significant wildfire events. Photo George Wuerthner

Third, it’s essential to question the belief that Indian burning kept fuels low and contributed to “healthy forests’. This notion can be considered an urban myth.

Numerous studies have shown that Indian burning was primarily local, typically around village sites and other high-use areas, raising doubts about its effectiveness in reducing wildfires across the landscape.  

Large blazes are recorded even when Native Americans occupied the landscape and were presumably active in cultural burning. A study in the Siskiyou Mountains of northern California and southern Oregon examining a 2000-year sediment record found that 77% of 68 major fires occurred before Euro-American settlement.

Even in the heavily populated Willamette Valley which had one of the denest populations of Native Americans, research found that tribal burning influence was mostly localized. Photo George Wuerthner

For instance, a study done by Cathy Whitlock in the Willamette Valley of Oregon, which had some of the densest Native American populations in the West, concluded: “The idea that Native Americans burned from one end of the valley to the other is not supported by our data … Most fires seem to have been fairly localized, and broad changes in fire activity seem to track large-scale variations in climate.”

Ponderosa pine near Mill Creek, Ochoco National Forest, Oregon. Photo George Wuerthner

Advocates of native burning typically suggest that cultural burns keep forests healthy. One has to ponder how ponderosa pine, which thrived as a distinct species for over 55 million years, managed to maintain its health all those millions of years before humans arrived less than 20,000 years ago.

At a landscape-scale influence, there is no evidence that Indian fires kept the forest “healthy” or reduced large-scale wildfires.

Fourth, fuel reductions may work to reduce or slow fires under ordinary fire weather conditions but are ineffective during the 1-2% of the time when large wildfires occur. These blazes are dominated by extreme fire weather conditions, particularly ignition with high winds.

For example, from 1970 to 2002, on U.S. Forest Service lands, 1 percent of all fires burned 97.5 percent of total area.

Wind is the most important factor in creation of large unstoppable wildfire. Photo George Wuerthner

Wind is critical to all large blazes. Wind fans the flames by delivering a crucial component – oxygen – to a fire and directing the fire’s spread. High winds cause flames to heat and eventually ignite vegetation in front of it. They often carry embers to unburned areas, starting a spot fire. Extreme heat and sun will accelerate the drying of fuels, making them easier to ignite.

Under such extreme fire weather conditions, high winds loft embers through and over-prescribed burns. A 2023 paper that reviewed the “beneficial effects” of prescribed burning admits: “Under the most extreme conditions, even the best treatments may fail to prevent high-intensity fires with the potential for substantial impacts on both the ecosystem and human welfare.”

The Eagle Creek Fire burned a portion of the Oregon side of the Columbia Gorge and high winds tossed embers across the mile-wide Columbia River to ignite fires on the Washington side. Photo George Wuerthner

Extreme fire weather conditions cause unstoppable wildfires like the Holiday Farm, Bootleg, Cedar Creek, Eagle Creek, and other recent large Oregon conflagrations, which in one way or another have significant natural or human fuel reductions.

 For instance, the Holiday Farm blaze raced down the McKenzie River, burning through and over numerous clearcuts. With the aid of high winds, the Eagle Creek blaze even crossed the mile-wide Columbia River to start ignition on the Washington side of the river.

If the barrier created by a large river won’t stop a blaze, believe that removing a small portion of the fuel with logging or burning can prevent or control a blaze?

The snag forest seen here in the Mount Jefferson Wilderness is one of the rarest habitat types since very quickly new forest growth overwhelms the area. Photo George Wuerthner

Finally, a philosophical issue with these Forest Service fuel reduction efforts is their inability to see the forest through the trees. The agency and most researchers start by assuming that large, high-severity blazes, where most trees may be killed, damage the landscape, and must be significantly reduced, if not eliminated. However, some researchers find stand replacement blazes critical to forest ecosystem health.

After such high-severity blazes, there are mushrooms, more birds, butterflies, bees, small mammals, and even more fish in streams where the logs from the wildfire create habitat.

Snags and fallen logs store carbon for decades, sometimes centuries. Millie Fire, Deschutes NF, Oregon. Photo George Wuerthner

Snag forests and the resultant downwood store carbon for decades and centuries.

Another concern is that prescribed fires can sometimes escape containment. Prescribed burns in New Mexico triggered two major blazes in 2022, including the Hermits Peak-Calf Canyon Fire, the largest in state history.

Due to these limitations and issues, the Forest Service and governmental authorities should reconsider their strategies in an era of climate warming. To the degree that prescribed burns are implemented, they should be located near the margin of communities and burned every few years. If you can’t guarantee burning, it is better not to do them.

The house foundation is all that is left of a home while the house in the upper right survived the blaze. Home hardening is the most effective strategy for protecting homes and communities. Photo George Wuerthner

However, the federal strategy of “active forest management,” including forest thinning and prescribed burning, is a less effective way to protect communities. A study in California analyzed the effectiveness of Home Ignition Zone (HIZ) characteristics for about 40,000 California buildings exposed to wildfire between 2013 and 2018 to determine the most critical features in preventing structure loss. After sorting the buildings into “survived” (about 10%) and “destroyed” (about 90%), statistical comparisons of the two groups showed that “hardened homes” were most strongly associated with surviving wildfire across California during the period of study.

We need more wildfire in our ecosystems, but the idea that prescribed fire emulates natural wildfire ignitions and will significantly reduce the acreage burnt under extreme fire weather conditions is questionable.

The Dixie Fire charred more than 900,000 acres in northern California. The hills in the background all burned during the blaze . The Dixie Fire was the second largest blaze in California history, yet the majority of the blaze burned at low-to moderate severity. Photo George Wuerthner

Lastly, even the largest blazes are essentially burnt at low severity. In dry forests that historically experienced low- and moderate-severity fires, these severity levels accounted for roughly 75 percent of the acres burned during the 1985–2010 period. In other words, one large blaze reduces fuel more at low severity than dozens of prescribed fires.





  1. George Delisle Avatar
    George Delisle

    I agree with the idea that native burning was usually limited to smaller lower elevation sites and not the large scale resource management that some would like us to believe.
    In my experience, low volume, short re-entry selection harvests are the best method to control the fuel loads and maintains a certain amount of biomass on the surface at all times to help maintain moisture and humidity levels. Pruning of the dead branches also helps allow moisture (rain) to penetrate the canopy and reach the ground more often. This also provides for a continuous input of nutrients over time. Fires deprive the forest of this moisture holding capacity and simplifies the ecosystem that leads to reduced Biodiversity.
    We can get up on our soapboxes all we want, but the real test of our convictions is how healthy is the ecosystem at the end of the day? Putting paper fences as reserves, in my experience, is not very effective in the drier ecosystems, maybe in the wet belt, the forest stands a better chance, but not the drier zones.
    I have been selective harvesting the same area for over 40 years now and the forest is a properly functioning ecosystem and according to the research that has been going on this area since 1997, a “species at risk” bird is thriving in it. I can show anyone interested the results of which I speak, if they are interested.
    George Delisle

  2. George Durkee Avatar
    George Durkee

    “One of the most important issues is that most wildfires never encounter a fuel reduction, whether from thinning or prescribed burns. So, even if prescribed burns were effective, fires seldom occur in treated areas.”

    Prescribed (aka Rx and, lately, “good” fire) fires and thinning are carried out for different management reasons. The main ones are to reduce danger to communities in the Wildland Urban Interface and/or to restore an ecologically healthy and diverse plant and wildlife community.

    I’m not very familiar with Oregon forests, but experience and data from California’s Sierra Nevada is beginning to show that, in fact, Rx (Prescribed) fire and thinning can significantly affect fire behavior. Several recent wildfires coming into Giant Sequoia groves in Yosemite and Sequoia Kings National Parks, for instance, became much less intense and became mostly ground fires with lower rates of spread. A number of these sequoia groves have had decades of Rx fire, mechanical thinning, or both to reduce vegetation (aka fuels) to pre-fire suppression density and forest diversity. Wildfires that have gone into untreated giant sequoia groves, though, have been catastrophic – burning huge numbers of the ancient “monarch” trees.

    There’s extensive research on giant sequoia groves and other coniferous forests in the Sierra. All indicate a fire return interval of 8 – 15 years or so. In sequoia groves, tree ring analysis shows these fires to have been fairly limited in size. This makes sense since repeated fires (caused by lightning or indigenous peoples) reduced vegetation density, reduced “ladder fuels” that created hotter crown type fires, and created a mosaic type forest with open areas that would further reduce fire spread and intensity.

    “Second, the burn must be repeated every few years—forever to be effective. By removing competing vegetation, plant regrowth is rapid.” Well, yeah, that’s kinda the point. The idea is to restore fire to the landscape — coupled with mechanical thinning as indicated — to reduce vegetation density. “Plant regrowth is rapid” is a feature, not a bug. As forest density is reduced (fewer trees per acre) and the lower branches of trees removed, then there’s more light on the forest floor as well as creating large open areas — a mosaic effect for the entire landscape. Instead of a dense thicket of even aged trees of the same species, fire can restore a landscape of multiple species — trees and herbaceous vegetation — which also provides for much greater diversity of wildlife.

    “This area was burned just two years prior, and already the regrowth of grass has largely negated any beneficial effect on potential fire spread.”
    The author seems to misunderstand the management reasons and effect of reintroducing fire. Yes, vegetation regrows and, yes, fire will — and should — return. The effect, though, is that fire return will be much less intense, will often (though not always) burn as a low-level ground fire, and will be easier to contain as they approach communities.

    For 20+ years, Lake Tahoe has carried out an impressive multi-agency effort to reduce vegetation density throughout the basin. When the recent Caldor fire burned into the basin, there was extensive structure loss in the untreated areas but almost none in the treated areas (

    I’m less sure of the extent of indigenous burning but strongly suspect it was much more influential than the author suggests. Fires started by Native Americans would burn until they go out but, if fire was a common occurrence, they’d be limited in size. Pre-European contact, the indigenous population of California was likely huge. Burning to favor oak and other species critical to their lives, as well as encourage wildlife with a more open understory, was likely much more extensive throughout California before their numbers were decimated by disease and genocide. I’m not clear that the studies the author cites reflect those much larger pre-contact communities and indigenous burning.

    Misrepresenting the effects and management goals of prescribed fire as it does, this article does a disservice to efforts to reestablish fire as a tool to both restore a more ecologically diverse landscape as well as mitigate the threat to communities in the wildland urban interface.

    Maybe TMI but here’s a few articles:
    Giant Sequoias Are No Stranger To Fire

    Did Prescribed-Fire Treatments Moderate Effects of the 2015 Rough Fire on Giant Sequoias in Grant Grove, Kings Canyon National Park?

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George Wuerthner is an ecologist and writer who has published 38 books on various topics related to environmental and natural history. He has visited over 400 designated wilderness areas and over 200 national park units.

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George Wuerthner