Focus on how treatments affect ‘extreme’ fires
By Ann McCreary
Fire ecologist Susan Prichard of Winthrop has been studying wildfires, and their impacts on forests, for more than two decades. Even so, she was unprepared for the intensity of wildfires she witnessed in the Methow Valley and Okanogan County during 2014 and 2015.
“As a fire ecologist, I really have had enough wildfires in my backyard for my career. When the Carlton Complex Fire hit, I was shocked at what an extreme event it was,” Prichard said.
Prichard is launching a new research project that will examine, among other things, whether efforts to reduce fuels in forests can make a difference in extreme wildfires like the Carlton Complex.
Prichard’s previous research has focused on whether forest fuel reduction projects — thinning and prescribed burning — improve the resilience of forests. Her work includes a study of the 2006 Tripod Fire, which burned 175,184 acres in the Okanogan-Wenatchee National Forest north of Winthrop.
“I had described the Tripod as really extreme fire behavior,” Prichard said. “It was a little humbling because when Carlton Complex happened eight years later, the difference was surprising.”
Prichard’s new study will evaluate the effectiveness of forest treatments, including thinning and prescribed fire, in the Carlton Complex and Okanogan Complex fires of 2014 and 2015. The three-year project, funded by the federal Joint Fire Science Program, will also examine whether those treatments helped efforts to fight the fires.
The project is similar to her previous research, but Prichard said studying a fire that hit so close to home has a personal element that gave her pause.
“The Carlton Complex was pretty emotional. To think through doing another treatment evaluation … I had to gear up for it. But we really felt like we had to do it,” she said. Prichard, who works for the University of Washington School of Environmental and Forest Sciences, is principal investigator for the study and leads a team of five other scientists.
Studying the Carlton Complex and Okanogan Complex fires will provide insight into whether fuel reduction treatments are helpful under conditions that create extreme fires — conditions that are predicted to become more common in a warming climate, she said.
“The Carlton Complex and Okanogan fires felt like climate change fires — hotter, drier, mega-fires,” she said.
“We know that prescribed burning mitigates fire effects … there are a lot more green trees and forest resilience” in areas treated with prescribed burning, Prichard said. “In lower-elevation mixed conifer forests, if fuels are reduced by prescribed burning, it mitigates the next wildfire. It means flame lengths are generally shorter and fire intensity is lower.
“What we don’t understand as well is what about these worst-case scenario fires like the Carlton Complex and Okanogan Complex?”
Those worst-case scenarios were created in 2014 and 2015 by prolonged regional drought. The days preceding the Carlton Complex and Okanogan Complex were extremely hot and dry, Prichard said. Those factors created conditions that sucked the moisture out of fuels (vegetation), priming them to burn. Combined with strong summer winds, the circumstances produced the two largest wildfires in Washington’s history. Scientists have predicted that those conditions may become more common, as climate change produces hotter, drier, longer fire seasons.
“With continued climate warming, wildfire seasons of similar duration and severity to the 2014 and 2015 fire seasons are increasingly probable,” Prichard said in a summary of her new research.
Initial observations of treated areas that burned in the Carlton and Okanogan complex fires indicate that in some circumstances the treatments did not prevent total loss from the fires, Prichard said.
“Anecdotally, when we drove through areas with fuel reduction treatments we saw treatments that aligned with wind, and so they didn’t fare well. They were exposed to the superheated temperatures and had high mortality and severe fire effects despite the treatment, which is painful because fuel treatments take a lot of planning, time and money,” she said.
Prichard will conduct a retrospective study of past fuel reduction treatments and burn severity for the Carlton and Okanogan complex fires to provide an in-depth analysis of whether and how prior treatments mitigated wildfire effects.
“We will identify thresholds under which treatments were ineffective — including treatment type, size and configuration, time since treatment, topographic position, and exposure to prevailing wind,” Prichard said in her project summary.
The research will help the different agencies involved in managing public and private lands evaluate how and when treatments are successful.
“We know under more moderate conditions, fuel treatments moderate fire effects. We won’t always have Carlton and Okanogan complex-type events,” Prichard said. “Is there a threshold effect? How much needs to be treated to be effective? How do treatments and landforms interact? We know most wind is down valley. Where can we strategically place fuel treatments?”
To evaluate how treatments assisted firefighting operations, researchers will conduct interviews with fire management teams involved in the fires “to compile lessons learned about specific ways treatment type, configuration and landscape position assisted in safe and effective wildfire response, and where such treatments failed,” Prichard said.
“Another task is to reconstruct fire progression and how incident response teams made use of those treatments…as anchor points for burnout operations or to help build contingency lines to protect communities,” she said.
Researchers will also create simulations of fire spread, intensity and suppression difficulty to assess how treatments could be better configured to be more effective in making landscapes resilient to wildfire, within constraints imposed by nearby communities, management boundaries and valuable natural resources.
To reconstruct the 2014 and 2015 wildfire events, “we’re truly going to have to turn into detectives,” Prichard said. The work will include examining satellite imagery and reviewing all the written records of the fires. For instance, researchers will read the daily action plans prepared by fire managers, and compare the plans to what actually happened, Prichard said.
Prichard’s research is being conducted in support of the National Cohesive Wildland Fire Management Strategy, to better understand where and when fuel reduction treatments will mitigate wildfire behavior and assist in fire management. The national strategy is an initiative, mandated by Congress, to work collaboratively among all stakeholders and across all landscapes, using best science, towards the goals of developing resilient landscapes, fire-adapted communities and safe and effective wildfire response.
Local stakeholders in wildfire management include the Confederated Tribes of the Colville Reservation, U.S. Forest Service, Washington Department of Natural Resources, Washington Department of Fish and Wildlife, and private landowners, Prichard said.
“Because fire heeds no administrative boundaries, our emphasis on multiple land ownerships will be particularly useful in evaluating how future fuel reduction treatments can be coordinated across ownership and land allocations,” she said.
Public mistrust of some agencies like the Forest Service, which grew out of past logging practices, has produced some mistrust of current fuel reduction and forest restoration strategies, Prichard said. “The evidence is just unequivocal that fuel treatments do work under most circumstances,” Prichard said. “We can’t control the weather. The only thing we can alter is fuels.”