My first experience fighting a wildfire came in 1962; the same year naturalist Rachael Carson published Silent Spring, the book that jolted me and other Americans into awareness of ecological relationships and how important they are to life on earth. The following summer, as a trainee ranger in Sequoia-Kings Canyon national parks brought me a bit of insight about “fire ecology.” First, as a raw recruit in the days before Nomex, I was sent with a few other Park Service folks to hold the ridgetop fire line on one of Professor Harold Biswell’s pioneering “controlled burns” to improve brush covered ranchland just west of the park boundary. Also, in the park I noticed how all the giant sequoias had char on their trunks, from long-ago fires. Then I heard a naturalist explain that it would be hard to find an uncharred sequoia, because these great trees owed their existence to frequent surface fires. I heard talk about putting fire back in this big-tree forest.
The following summer, working in Olympic National Park brought me a little more insight about fire ecology. I learned that the gigantic coastal Douglas-firs in the rain forest had arisen after ancient fires, without which there would be only dense stands of smaller hemlock. Higher in the mountains I hiked through some old forests that were astoundingly dark at mid-day, and consequently had very little understory vegetation. Then, crossing into an old burn, I encountered a luxuriant assemblage of young trees and tall flowering shrubs.
In 1965 I enrolled as a graduate student and began to study forests in the Northern Rockies. At first, like many others I gathered that big stand-replacing fires had always been the norm. However, a few years later my new job as a forest ecologist had me examining all types of old, undisturbed forests in Montana. To my surprise about 70 percent of these mature forests had fire scars on living trees, indicating they had survived lower intensity fires in past centuries. Even a large proportion of the lodgepole pine forests had experienced these sub-lethal fires. Clearly, the role of fire was more varied and complex than I had thought.
During the last half-century, scientific knowledge of the importance of fire in maintaining forest ecosystems has mushroomed, and spread in some measure even to the outdoors-conscious public. However, most Americans including firefighters have a mixed bag of perceptions about wildland fire. Fear, loathing, and denial–refusal to deal with the inevitability of fire–often carries more weight than recognition of fire as an intrinsic part of the ecosystem. The former attitude has deep historical roots, and was expressed by the US Geological Survey scientist who made a detailed survey of the Bitterroot Forest Reserve in the 1890s: “The after effects of fires in this region are various, but are always evil, without a single redeeming feature.”i
Based on my experience studying fire, and observation of fire control efforts and public perceptions of wildland fire, I believe that an understanding of fire ecology would benefit the public (especially residents of the Urban-Wildland Interface), and help forest managers, fire managers, and firefighters in their work. This would also benefit forest ecosystems. I’ll explain why.
Fire is inevitable, but we can manage it
For several decades a multimillion dollar advertising program seemed to promote fire exclusion—for example with the slogan “Only you can prevent forest fires” imposed on the stark image of an incinerated forest with forlorn deer looking on. These messages along with the enormously popular movie Bambi conveyed the impression that forest fires are an unnatural plague caused by careless humans. Although Wildfire readers recognize that such advertising was oversimplified and at least somewhat misleading, much of the public does not. More recent advertising is an improvement–emphasizing the need for forest visitors to be careful with fire. However, it generally doesn’t speak to fire’s intrinsic role in the forest or undo the widespread perception that fire is basically unnecessary and destructive.
Countless millions of WUI residents and forest visitors don’t really recognize that forest fuel accumulation and abundant sources of ignition have since time immemorial made fire a major force shaping North American forests, and that modern technology cannot change this reality. I have pointed out to WUI residents that their ponderosa pine forest drops one to two tons of cured, highly combustible pine needles and cones per acre each year. Because of its light weight, this amount of forest litter might fill a dump truck! In the semi-arid climate, where fire can spread readily during about half of each year, living in an untreated ponderosa forest is comparable to being surrounded by acres of waded up newspaper. Wildfire readers know that thinning and fuel removal or burning treatments coupled with making a home’s exterior fire-resistant has proven very effective in preventing damage from wildfire. However, the need to act on this fire ecology knowledge has not been recognized by the public at large, lawmakers, and insurance providers.
Even lesser known is the fact that experience with allowing some natural fires to burn in national parks and wilderness areas shows that after several years, new fires become fuel-limited as they run into previously burned areas. This fosters a mosaic pattern of burning on the landscape rather than mega-fires that envelop vast areas. Similarly, the public is generally unaware that forestry/fuel reduction treatments—another application of fire ecology–can help mitigate against massive, severe wildfires.
Fire is necessary
For more than half a century, forest fire prevention campaigns begged the question of how we can control the inevitable buildup of dead and living fuels if we exclude fire from fire-dependent forests. By the late 1970s the increasing scale of severe wildfires convinced the US Forest Service, leader in the fire prevention campaign, that fire exclusion wasn’t working. In response, the agency announced a change of course in which it would begin to emphasize management of fire and fuels.
Progress in implementing this transition has been hindered by limited funding, public objections to prescribed burning, and a host of environmental protection issues. Thus, increased accumulation of dead and living fuels continues to be a major factor supporting ever-larger wildfires. Ironically back in 1943 the Journal of Forestry published a detailed analysis by a government forester, Harold Weaver, presenting the case for either restoring the ecological role of fire in a major Western forest type (ponderosa pine) or finding a suitable substitute for historical fires. More than 70 years ago, Weaver supplied evidence that increasing dead fuels and understory tree thickets made these forests more susceptible to damage from wildfires and insect and disease outbreaks.
More recently studies have found that the fires of the distant past recycled soil nutrients and led to an infusion of fire-dependent herbs, shrubs, and even shade-intolerant tree species that contributed greatly to biodiversity, wildlife habitat, and subtle effects such as limiting the spread of root disease. The more science has learned about natural ecosystems such as forests of native trees, the more it recognizes the important role fire plays in maintaining them.
Fire is beneficial
Without occasional fires throughout past centuries many of the valuable and iconic trees of American forests would have become scarce or absent—these disturbance-dependant trees include eastern white pine, white oak, longleaf pine, and many others in the eastern U.S., and giant sequoia, western white pine, sugar pine, and western larch in the West. Also, several other important trees were abundant, long-lived and attained great size historically largely because they are better adapted to fire than their shade-tolerant competitors. This group includes several eastern and Midwestern oaks, tuliptree, black walnut, and other hardwoods, and West coast Douglas-fir and ponderosa pine. A variety of shade-intolerant trees, fruit-bearing shrubs, and nutritious herbs that are important for biological diversity and wildlife habitat are disturbance-dependant and were abundant historically due to the role of fire.
Importance to Firefighters & Fire Managers
Fire ecology helps us understand forest ecosystems and thus recognize fire as an intrinsic and necessary force of nature. The new resident in a dense second-growth ponderosa pine forest asked me for advice about taking care of his 10-acre home-site. We walked through his property and an adjacent tract, locating remnants of the original late-1800s forest—old-growth pine pitch stumps. We concluded that the original forest was dominated by widely spaced big, old pines, and several stumps contained scars from multiple surface fires that the trees had survived. This helped the landowner to see that he had an over-abundance of small trees, and that thinning them and reducing the forest fuels made sense ecologically as well as for the safety of his home.
When firefighters and fire managers recognize that society’s best strategy is to adapt homes and property to fire and to pro-actively manage fire and forest fuels, they have a better perspective for carrying out their mission. With an appreciation of fire as an intrinsic part of the forest ecosystem, firefighters will recognize that forest residents are responsible for making their homes fire-resistant and maintaining low-hazard surroundings. For instance, during the year 2000 wildfires in western Montana, several forest homes survived because homeowners had carried out fuel-reduction treatments. Understanding fire ecology should help prevent firefighters from taking risks to “save” the forest or a forest residence under threatening conditions. Instead they can look for strategic opportunities to establish control when and where conditions are more favorable. Also, in their contacts with the public, ecologically-aware firefighters and fire managers have credibility and an opportunity to advise people about the role of fire in the forest and how we all can best deal with it.
i John B. Leiberg, “The Bitterroot Forest Reserve,” U.S. Geological Survey, 20th Annual Report, Part V (Washington, DC: U.S. Government Printing Office, 1900): 388.
About the author
Stephen Arno is a retired US Forest Service research ecologist who lives in Florence, MT. He has a Ph.D. from the University of Montana, and is the author of Flames in Our Forest: Disaster or Renewal, Mimicking Nature’s Fire, Northwest Trees: Identifying and Understanding the Region’s Native Trees, and other books and articles. He and his wife have actively managed their 60-acre family forest for over 40 years, using selective cutting and burning to restore a semblance of the open-grown forest of large ponderosa pines that was logged in the 1880s.