MYTH: FUEL BUILD UP IS RESPONSIBLE FOR LARGE BLAZES?
A conventional narrative is that wildfires in the western U.S. are unprecedented and more extensive than in the past. This increase in fire acreage is attributed to “fuel build-up,” presumed to be the result of successful fire suppression. However, such assertions lack context. Compared to the past, we still have a fire deficit.
For example, according to the Boise Interagency Fire Center between 1900 and 1940, there as many as 50 million acres burned annually. One of the largest wildfires in historic times, the 1910 Big Burn, raced across 3.5 million acres of northern Idaho and western Montana occurred in this period, long before anyone can argue there was “fire suppression” contributing to fuel build-up.
During the period between the 1940s and late 1988, when Yellowstone burned, there were few large fires due to Pacific Decadal Oscillation—an ocean current that brought cooler, wetter weather to the West. The lack of large blazes during these decades is attributed to “successful” fire suppression; however, it was also a period of cooler and moister climate. Nature was “successful” at putting out blazes.
Then beginning in the late 1980s, the climate warmed considerably with “historic” drought conditions across many parts of the West, and large wildfires once again became common-in spite of even better firefighting ability and equipmentWith climate change we can expect larger blazes to become more common.
A further nuance is that fuel build-up to the degree it has occurred due to fire suppression likely only applies to some ponderosa pine communities (but not all ponderosa pine are characterized by high frequency and low severity fire—80% of the higher elevation ponderosa pine stands in the Colorado Front Range are characterized by high severity blazes).
Most plant communities in the West burn at long intervals and often at high severity. This includes chaparral, juniper, sagebrush, all hemlock, most fir, aspen, and many higher elevation pines, including lodgepole pine and western white pine. All have fire rotations often running from many decades to hundreds of years.
Lodgepole pine in Yellowstone typically experiences large blazes every 200-400 or more years. Therefore, it is entirely natural for “fuels” to build up over this time, and given a window of hundreds of years, even if fire “suppression” were successful, it would not have any influence on fuels since dead materials in these forests naturally accumulate over many decades.
ACTIVE FOREST MANAGEMENT WILL PROTECT COMMUNITIES
It is often assumed that logging projects, including thinning, around the West, will stop large blazes during extreme fire weather conditions and/or reduce smoke and therefore protect communities.
However, large blazes are controlled by “top-down” influences like climate/weather, not fuels.
All large fires burn during extreme weather conditions of low humidity, high temperatures, drought, and, most importantly, high winds. Under less than extreme conditions, most fires are easily contained; however, the majority of these blazes are small–burning less than 100 acres.
For instance, a total of 56,320 fires burned over 9 million acres in the Rocky Mountains between 1980-2003. 98% of these fires (55,220) burned less than 500 acres and accounted for 4% of the area burned. By contrast, only 2% of all fires accounted for 96% of the acreage burned. And 0.1% (50) of blazes were responsible for half of the acres charred.
Yet the overwhelming observation is that under extreme fire weather, no amount of logging/thinning significantly influences fire behavior. Under wind-driven conditions, embers are tossed miles ahead of a fire front.
For instance, the Eagle Creek Fire in the Columbia Gorge jumped the mile and half wide Columbia River (with zero fuel) to ignite fires on the opposite shore. The landscape burned by Camp Fire that destroyed Paradise, California had had two previous fires in the past ten years (fuel reduction), had been extensively logged on private lands (fuel reduction) while the Forest Service had done hazardous fuel reductions on public lands.
In much of the West, the largest blazes are not even in forests. The 282,000-acre Thomas Fire that charred the hills about Santa Barbara, as well as the recent 98,000-acre Woolsey Fire that burned near Los Angeles, was in chaparral. The 558,198-acre Long Draw Fire that was the largest in Oregon history occurred in sagebrush.
In a 2017 letter to Congress, more than 250 scientists opined that logging and thinning were ineffective. To quote from their message: “Thinning is most often proposed to reduce fire risk and lower fire intensity…However, as the climate changes, most of our fires will occur during extreme fire-weather (high winds and temperatures, low humidity, low vegetation moisture). These fires, like the ones burning in the West this summer, will affect large landscapes, regardless of thinning, and, in some cases, burn hundreds or thousands of acres in just a few days.”
The idea that fuel reduction from logging/thinning or even prescribed burning is effective is questioned by many researchers. This is a representative sample from scientists at the Missoula Fire Lab. “Extreme environmental conditions . .overwhelmed most fuel treatment effects. . . This included almost all treatment methods, including prescribed burning and thinning. . .. Suppression efforts had little benefit from fuel modifications.”
This view was echoed by the Congressional Research Service (CRS), which stated in a report to Congress “From a quantitative perspective, the CRS study indicates a very weak relationship between acres logged and the extent and severity of forest fires. … the data indicate that fewer acres burned in areas where logging activity was limited.”
One of the problems is that our western landscapes are so vast, and predicting exactly where a fire might ignite is impossible. Research has shown that the probability of a fire encountering a “fuel reduction” during any period when it might be useful is less than 1%.
Plus, thinning/logging opens up the forest to greater heating and wind penetration, often exacerbating the conditions that encourage blazes. One study of 1500 fires found that actively managed forests (i.e., logged/thinned) tend to burn at higher severity than protected landscapes where presumably fuels are greater.
MYTH: DEAD TREES CONTRIBUTE TO LARGER BLAZES
Another assumption is that dead trees resulting from insects, disease, or previous fires will contribute to more massive fires. Yet research from throughout the West shows that forests experiencing insect outbreaks or other sources of mortality are less susceptible to fire. This is because what burns in a blaze are “fine fuels” like needles, cones, small branches, shrubs, grass, and other easily burnable materials. This is why we get snags after insect outbreaks or fires. The larger trunks that remain lack the fine fuel to carry crown fires.
Ecologically speaking, dead trees are critical to healthy forest ecosystems. More wildlife species depend on dead trees for their survival than green trees. The second-highest biodiversity found in forests after old-growth stands occurs in the snag forests that result from high severity blazes.
MYTH: LOGGING FORESTS BEFORE THEY CAN BURN HELPS FIGHT CLIMATE CHANGE
Burning forests release relatively small amounts of carbon. Most carbon remains on site in snags, roots, and burnt wood. Charcoal that results from high severity fires is one of the best carbon storage mechanisms available. By contrast logging and wood processing releases far more carbon. For instance, an Oregon Global Warming Commission 2018 report found that even in very active wildfire seasons, wildfires average ~10% (some years as low as 3%) of the states’ total greenhouse gas emissions. By comparison, logging contributed to more than three times more emissions.
Several Oregon State researchers concluded that “logging harms our carbon balance for decades. “By accounting for more of the benefits and costs involved in reducing the risk of crown fires, modifying storage in long- and short-term products, and in substituting wood products for fossil fuel (biomass), we find that thinning existing forests to reduce crown-fire risk increases net carbon emissions to the atmosphere for many decades… “
 1 Littell, J.S. et al. 2009. Climate and wildfire area burned in western U.S. ecoprovinces 1916-2003. Ecol. Applic. 19:1003-1021
 4Abatzoglou, J.T., and A.P. Williams. 2016. Impact of anthropogenic climate change on wildfire across western U.S. forests.
 William Baker 2009 Fire Ecology in Rocky Mountain Landscapes
 Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western United States Reinhardt et al. 2008
 Carbon implications of current and future effects of drought, fire, and management on Pacific Northwest forests. B.E. Law. *. , R.H. Waring. Department of Forest Ecosystems & Society, Oregon State University, Corvallis, OR 97331, USA B.E. Law ⇑, R.H. Waring