June 2022 Science Corner | Adapting western North American forests to climate change: Science to inspire a paradigm shift

For many of us, the beginning of summer means our minds and hearts turn to the upcoming fire season. Wildfires continue to ravage the west, and in recent years their devastating intensity and scale have only grown. Accompanying this escalating crisis is a growing scientific literature aimed at better understanding our western forests, how they are evolving, and what can be done to make them more resilient. To further this effort, recent publications have synthesized the hundreds, and even thousands, of papers exploring this topic into a comprehensive guide for scientists and practitioners. To provide new insights, a geographically diverse group of researchers focused on forests, fire, and land management came together over the course of several years to address three primary questions:

1. Do we know enough to understand why wildfires have gotten larger, more numerous, and more severe in recent years?
2. Do we know enough to act responsibly?
3. Should we act now, and to what extent?

The team of coauthors was led by Drs Susan Prichard, Keala Hagmann, and PNW USFS Researcher and Blue Forest Science Advisor Paul Hessburg, who came together to review and weave together the findings of the existing literature on these topics. Last August, their works were published as a trilogy by the ESA journal Ecological Applications. The three papers were part of the same workflow to assess, understand, and communicate the challenges of forest fire as a dynamic ecosystem component and politicized management topic.

These papers have an impressive, diverse group of co-authors. To this scientific team, it was important to include a regionally distributed group of authors to bolster credibility and ensure various geographies are properly represented. Ecology is place-based and site-specific. Having sensitive perspectives and considerations for different regions and biomes and how those features interact with various weather and climate factors is important for creating a holistic review.

The resounding takeaway and intended goal of these three papers is to encourage a paradigm shift around how we manage forests in the face of these catastrophic wildfires.

“Our reviews taught us, and hopefully others, that the science is deep and broad based,” said Dr. Hessburg. “The science is mature and we know enough to act at the scale of the problem. It is up to managers then to use that knowledge and act responsibly.”

The first paper, led by Dr. Hessburg, Wildfire and climate change adaptation of western North American forests: a case for intentional management, emphasizes the urgent need for active adaptive management and presents a roadmap for action. The paper recaps the science, describing how western forests have departed from their pre-European colonization condition and structure. At the same time, climate change, with hotter temperatures and less precipitation, makes fuels and forests drier and more vulnerable to ignitions for more extended periods. We worked pretty hard to hit the climate science literature as well in our review, and it’s impossible to conclude that climate change isn’t a big deal,” Dr. Hessburg explained. “It is an incomplete explanation to say it’s just climate or just fuels, the climate is clearly driving area burned.” Based on these changes and the best available science on management, the authors conclude with a series of recommendations for best practices that take a whole landscape approach to management, including fuels treatments and prescribed burning practices.

Dr. Hagmann’s paper, Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests, addresses the question of whether management is still warranted. Dr. Hagmann’s paper analyzes misinformation and arguments against management as a tool to restore resistance and resilience to wildfire and drought. The paper provides basic guidelines for a general audience to digest this dense data and understand critiques of anti-management claims. A major takeaway from this analysis is that some papers which claim management is harmful get to this conclusion by applying non-spatial data in a spatial way. Dr. Hagmann points out that that is an inappropriate application of non-spatial data, and this approach cannot be scientifically used to make claims opposing management treatments like thinning.

The background work by the author team was no small effort. Drs Hagman, Hessburg, and Prichard started with a core set of papers that generally oppose fuel reduction treatments to address overgrown and dense vegetation that have accumulated over more than a century of fire suppression policies. The team then read and analyzed the literature that critiqued those anti-management papers, and finally, analyzed the other articles cited in those rebuttal works. This systematic review and synthesis of looking at claims, rebuttals, and supporting literature brought the authors to over 2,000 articles read and reviewed for this endeavor! Over 1,000 of these were cited in the final versions of the trilogy of papers. “This is a complex topic, but it is also one that people have been looking at for at least a century now – there is a lot of work out there,” Dr. Hagmann said about the volume of papers reviewed.  Dr. Hessburg added, “There was much concurrence among the papers we reviewed. That was a key finding. But there were differences too, and we wanted to catch those as well. What are the major and minor threads we could pick out, and when have we trapped the nuances sufficiently to know we have complete stories?”

Finally, the third paper led by Dr. Prichard Adapting western North American forests to climate change and wildfires: 10 common questions follows the discussion of evidence and was actually the original catalyst for the entire project. This effort was focused on science communication as the authors wanted to create a resource that could help engage the public. Reaching non-scientists was especially important to the team as the impacts of severe wildfire deeply affect communities, both nearby rural areas, as well as urban centers hundreds, sometimes thousands, of miles away which are impacted by the wildfire smoke and evacuation orders.

Dr. Prichard led this paper to address common questions and concerns about proactive management to foster greater resilience of western forests to climate change and wildfires. “Polarization in the media sometimes portrays greater uncertainty within the science community on the topic of adaptive management strategies than actually exists. There is strong consensus among fire ecologists about the need for proactive management and the place-based tools for restoring resilience to fire-prone forests. Our paper synthesizes the literature and hopefully lays the foundation for increasing the pace and scale of treatments, including how we manage wildfires and support cultural burning practices,” explained Dr. Pritchard. Sustainable Northwest recently produced a new version of these findings in an interactive story map, which can be found here.

The authors hope this monumental effort will inspire a paradigm shift. These western forested landscapes are severely changed by past management actions. Years of excluding almost all fires have left western forests overgrown, which influences how animals, humans, and hydrology interact and respond to disturbance events on the landscape, both in the forest and adjacent ecosystems. These papers seek to support and encourage efforts to reintegrate fire while also restoring these landscapes to a more resilient state.

“For some people, this might seem like an academic issue,” said Dr. Hagmann. “Should this forest be saved or not? But people live in these landscapes and depend on them for everything from food to their cultural identity. For example, the Klamath Tribes live and depend on forest landscapes, of which more than 400,000 acres burned at unprecedented severity in the Bootleg fire last year. While we are debating, we are changing the trajectory of these people’s future.” These scientists hope their findings and these papers can contribute to an accelerated effort to restore these forest landscapes.

In the academic community, reactions so far have been positive and the papers have been well received by other scientists and managers. Dr. Hessburg told us, “Many said, ‘it is about time’. I live in a community where fire is a big deal and there are many firefighters and fire managers around the valley. Some have stopped me on the street and simply said, ‘thank you for doing this’. That is perhaps most gratifying. To be appreciated by folks who know fire, use fire on the ground, wild and prescribed, who know the forests, work in them, and regularly use the tools, that gives me the biggest rush.”