Fire ecology scientist Susan Prichard joined forces with colleagues to publish three articles that synthesize more than a century of research and observations of forests in the western United States and Canada.
Prichard, co-authors cite scientific basis for action
When Susan Prichard takes a break from her work as a fire ecology scientist, she often goes for a run on trails in the dry forests that surround her home near Winthrop.
Historically, those low-elevation ponderosa pine and Douglas fir forests had frequent fires that played an important role in a healthy forest ecosystem. Through a variety of causes, including more than a century of suppressing wildfires, the frequency of naturally occurring fire decreased, resulting in changes to the forests that make them more vulnerable to large and devastating wildfires.
For years, Prichard and other forest scientists have been advocating for proactive management of dry forests in the West, using thinning of trees and vegetation and prescribed burning to help forests survive and recover from wildfires that have become larger and more severe in recent decades.
During one of her runs two years ago, “I was really frustrated because there was another journal article released questioning the need for dry forest management,” Prichard recalled in an interview last week. “I felt the science was very clear – not only from the work I’ve done but from the work of my colleagues.”
Out of that frustration, she came up with the idea of developing a set of articles that would provide a thorough synopsis of current science about how human impacts – including climate change and more than a century of suppressing wildfires – have altered forests, and what needs to be done to help forests become more resilient.
Prichard, a research scientist at the University of Washington’s School of Environmental and Forest Sciences, teamed up with leading forest ecology scientists in the West to develop three articles that summarize the scientific literature about the need for more active management of dry forests. The articles were released in the journal, Ecological Applications, in early August as large wildfires were once again burning in the Methow Valley.
“We are living the real risk of catastrophic summer wildfires,” Prichard said. “These summer wildfires are difficult to live through. They’re scary, they threaten our communities. We have some hard choices. What solutions have some risk, or inconvenience? Can we make those hard choices so we don’t live through these devastating wildfires?”
Hotly debated
Years of record-setting wildfires have made clear the key ingredients to big fire years – drought, tinder dry fuels, lightning ignition and human-started fires followed by strong wind events, Prichard said.
“However, what – if anything – we can do about the worsening wildfire problems remains hotly debated in both the popular media and scientific literature,” she said.
The science of forest ecology is caught up in “polarization and politicization … that impedes implementation of effective land management plans, policies, and management by raising the volume of the disagreement, obscuring the line between facts, opinions and legal requirements; creating the impression that knowledge is more uncertain than it is, and increasing the time to resolution,” according to one of the articles, written by Paul Hessburg, a research ecologist with the U.S. Forest Service and affiliate professor at the University of Washington.
While land managers and policymakers recognize that the number and size of severe fires in western forests are rapidly increasing with climate change, agreement and funding to support climate and wildfire adaption are lagging, the scientists say. The articles published this month are intended to provide access to the best available science to help guide decisions and encourage action on forest management.
Prichard, Hessburg and Keala Hagmann, a University of Washington researcher, collaborated with more than 25 scientists from universities, conservation organizations and government laboratories across the West to review over 1,000 published papers. The three articles published this month synthesize more than a century of research and observations of forests in the western United States and Canada. The articles can be found online at: esajournals.onlinelibrary.wiley.com/toc/19395582/0/ja.
Their findings show that pronounced lack of fire over the past century has markedly changed the composition and structure of western North American forests, making large and severe fires inevitable, Prichard said.
Historically, naturally occurring fires in dry forests would have been smaller and more frequent, creating patchworks of forest, woodland, grasslands and shrub lands. That patchwork of burned and unburned areas created natural fire breaks that limited the size and intensity of fires.
Fire exclusion
A variety of causes, including modern fire suppression, livestock grazing, and curtailment of Indigenous burning practices, have resulted in the lack of fire – called fire exclusion. The lack of naturally recurring fire, ironically, contributes to increased fire severity and vulnerability to wildfires today. Fire exclusion has led to dense forests packed with trees and vegetation that fuel large and severe wildfires, particularly under drought and a rapidly warming climate, the authors say.
Prichard and her colleagues say their review of the scientific literature and the weight of the evidence indicate an urgent need for a wide range of approaches to reduce excessive fuels and make forests and surrounding communities more resilient – more capable of responding favorably – to wildfires and climate change.
They propose thinning of dense forests in fire-excluded landscapes, prescribed burning, reducing fuels on the ground, and practicing “managed fire,” which means allowing some wildfires to burn in backcountry settings under favorable fuel and weather conditions. They also recommend integrating western science with practices used for thousands of years by Indigenous people, who promoted healthy ecosystems by setting intentional fires.
But public support for those actions may be influenced by distrust or misinformation, Prichard wrote. “Since some treatments can involve the commercial sale of timber, they can be viewed through the lens of conflict over the role of timber production on federal, tribal and private forestlands. The legacy of mistrust from these conflicts affects how different groups perceive the science and its application in support of proactive efforts to increase resilience of forested landscapes.”
Answering questions
To address confusion and skepticism about forest management, Prichard authored a paper that discusses 10 questions that are commonly raised, addressing whether there is a widespread need for action, whether fuel treatments work in extreme weather, whether thinning should be concentrated in the wildlife-urban interface, and whether the scale of the problem is too great.
One of the questions addressed in Prichard’s paper is whether wildfires on their own can do the work of fuel treatments. Prichard notes that the current approach to modern wildfire management is still initial attack on unplanned fires. Only 2% to 3% of fire starts escape suppression, but they generally occur in the height of fire season and account for over 90 percent of the area burned annually.
Prichard and her co-authors describe how more than a century of fire exclusion and past forest management practices have jeopardized forest biodiversity, water quality and quantity, stability of carbon stores, recreation and air quality.
“Adaptive management cannot return landscapes to any historical condition or fire regime, nor is that a particularly useful goal at this point in time,” Prichard wrote. “Instead, intentional management focused on adapting current forest conditions to a rapidly evolving climate future is urgently needed.”
