Federal agencies lagging with prescribed burns for the year
When wildfire burned through a federal research area in Klamath National Forest this summer, scientists were dismayed to see more than 20 years of work go up in smoke.
But when they returned to the charred study area near California’s northern border, they realized they’d been given a unique opportunity.
Although the scientists had set out to understand how the thinning and controlled burning of vegetation could help regrow large trees more quickly, they now had a chance to study another urgent question: Could these same treatments make forests more resilient to wildfire? Or more specifically, could they moderate fire behavior so that flames were less intense and firefighters would have a better chance of snuffing a blaze before it barreled into a populated area?
The answer yes.
“In areas where we didn’t do anything, the untreated controls, the predominant fire behavior was a crown fire which killed every tree and consumed the entire tree crown,” said Eric Knapp, research ecologist with the U.S. Forest Service.
However, the plots that had been thinned and then treated with broadcast burning – in which an area of land is set alight to mimic naturally occurring wildfire – emerged relatively unscathed, he said.
The results, once confirmed, will rank among the strongest scientific evidence supporting the effectiveness of these so-called fuels treatments, Knapp said. But they were not unexpected. Researchers have found in the past that the best outcome is reached by the combination of thinning crown fuels, or tree canopy, and burning surface fuels, or vegetation on the ground.
Despite this knowledge, however, the federal government, which manages about 57% of the forested land in California, has completed only half of the fuels treatments it had hoped to get done in the state for the year – a statistic appeared to be
aresounding that profoundly dismayed wildfire experts.
As of mid-September, the Forest Service had completed or contracted out fewer than 37,000 acres of prescribed fire projects in California since Oct.1, 2020. The majority was the burning of stacks of vegetation that had been piled after thinning, in which crews prune branches or cut down smaller trees, often using chain saws or cranes.
An additional 6,063 acres of managed land included naturally ignited fires that were allowed to burn – a practice the Forest Service suspended after it came under heated criticism over the summer.
Another 5,000 acres were treated with broadcast burning, which in combination with thinning has shown to be most effective.
“That’s just depressing,” said Lenya Quinn-Davidson, fire advisor for the University of California Cooperative Extension. “That’s so little, given how much land the Forest Service manages in California. It is just a drop in the bucket.
“I think it speaks to the need for such drastic change around prescribed fire.”
In total, the Forest Service had, as of Sept.17, met about 54% of its goal of treating 238,200 acres in the state during the fiscal year, which ended Sept. 30. The target does not discriminate between prescribed burning and other methods of vegetation removal. Those include grazing, thinning, chemical treatments such as herbicide, and disposing of the thinned vegetation, including biomass removal, chipping, crushing and piling.
The U.S. Bureau of Land Management and the National Park Service, which manage much less forested land in California, didn’t fare any better. The NPS performed a total of 616 acres of broadcast burning in the state so far this calendar year; the BLM plans to burn about 300 acres but has yet to begin.
Officials say the lag in forest treatment is due to several factors, including lack of funding and personnel, but also to fundamental changes in the fire season. They say that drought, climate change and fuel overloading have stretched out the season and narrowed the time frame in which prepared burns can be conducted.
“There’s a lot of structural issues that need to be overcome to burn at the scale that is needed,” Knapp said.
The Klamath study, dubbed the Goosenest Adaptive Management Area, is a patch of old timberland that was heavily logged before it was turned over to the Forest Service in the mid-1950s. Before it was privately managed, fires had burned through the area every nine years or so, but by the time researchers began to focus on the area, it had not burned in decades, Knapp said.
The parcel was crowded with young trees competing for light and resources, and they had transitioned from primarily pine to fir, which is less fire- and drought-tolerant, he said.
Scientists were trying to see if they could remove some vegetation to re-allocate the growth to fewer trees, making them grow larger more quickly and restoring the forest to something that more closely resembles what it looked like a century ago.
They put in place three treatments: thinning favoring the reestablishment of pine species; thinning favoring pine species plus two rounds of broadcast burning, in 2001 and 2010; and thinning favoring the largest-diameter trees with no regard to species. Each was repeated on five 100-acre plots. Five control plots received no treatment.
The lightning-sparked Antelope fire burned through all of the plots over the course of four days starting Aug. 4.
“Because we have five replicates of each of these treatments that were all hit by fire burning under oftentimes similar conditions, we can tease out the effect of weather and the effect of fuels,” Knapp said. “It will be a very compelling example of the interaction of fuels treatments and weather in affecting the outcome.”
Initial observations suggest the plots that were thinned and burned fared the best, the control plots the worst, and the plots that were only thinned made out somewhere in the middle. There was little noticeable difference between the two types of thinning.
“What it shows to me is that under the most extreme fire behavior, thinning alone is oftentimes not enough,” Knapp said. “You have to also deal with the stuff on the ground.”
That’s not to say thinning alone didn’t change fire behavior, he said. Though many of the trees in the thinned plots still died, they were killed by heat, their needles scorched brown. By contrast, the trees in the control plots were entirely consumed by fire, leaving behind only dead, blackened sticks.
That suggests the thinned plots experienced a hot surface fire. The control plots, however, experienced even hotter fire that reached up into the crowns and burned the canopy, likely spitting out embers ahead of the main fire that made it move more quickly, Knapp said. Such variations in intensity and speed could mean the difference between firefighters being able to battle the fire or being forced to retreat.
Traditionally, parts of California would get a rainstorm in late September or early October, and broadcast burning could start a couple of weeks later once the vegetation dried out, Knapp said.
But in the last few years, fall rains haven’t arrived until late October or November. By that time, the sun angle is so low on the horizon and it’s so cool that the rain-soaked vegetation might never dry to the point where these burns can be conducted, he said. And even once the right conditions are in place, fire smoke and air quality considerations limit the number of burns that can be performed at once, Knapp added.
At the same time, fire seasons have grown longer and more intense, so the crews that once transitioned from fighting blazes to setting them are no longer available because they are still in fire suppression mode.
The National Interagency Fire Center reached its highest preparedness level, 5, in July, the earliest point in a decade. The designation indicates that 80% of the nation’s wildland firefighting personnel are committed to incidents.
U.S. Forest Service Chief Randy Moore cited those resource limitations in August when he announced the agency would no longer consider conducting prescribed burns until the preparedness level dropped back down to 2.