Why Large Fires are an Ecological Necessity
This winter California suffered its most severe drought in decades, with record-low rainfall and meager mountain snowpack. Drought, high summer temperatures, and wind together make the perfect storm for what some have termed “mega” forest fires that, in spite of fire suppression activities, sweep across the landscape and end only when winds die down and weather cools off. The western U.S. may be facing another year of large fires, as these typically follow drought. So why aren’t we, as wildlife and forest scientists, worried?
Despite the impression fostered by many in the media, politicians, the timber industry, and the U.S. Forest Service that large fires are widespread and destructive, they are actually infrequent and ecologically necessary. In non-drought years, western forests experience few fires big enough to affect the landscape. When you add up all the acreage burned in the biggest fires over the past decades, it is a tiny fraction of the area historically shaped by fire. Most importantly, fires in California and across most of western North America are as natural as sunlight and rain, and have been burning in forests, shrublands, and grasslands regularly since the end of the last ice age. Natural fires include the low-burning small blazes that consume leaf litter and small saplings as well as the biggest, hottest fires that kill all the trees in a large area. In fact, the term “mega-fire” is just another name for a large fire. Not only are these fires natural, but they are ecologically necessary for the survival of many plant and wildlife communities. For these species, years with no large fires are bad fire years.
For many plants and animals large fires create the very best habitat. The occurrence of large forest fires creates special conditions—standing dead trees, fallen logs, resprouting shrubs, naturally regenerating conifer saplings, and nutrient-rich soils that set the stage for the new forest to follow. Because large intense fires burned regularly over millennia, it is not at all surprising that many plants, insects, birds, and other animals evolved to take advantage of these unique conditions. Many species are now dependent upon intense fire to create their prime habitat—habitat that is now much rarer than it was historically, due to fire suppression and post-fire logging. The remarkable boom in plant and wildlife populations in the aftermath of large forest fires more than outweighs the negative effects from some animals that prefer unburned or lightly burned forests. Moreover, contrary to popular myth, even large, intense forest fires move relatively slowly, unlike fires in grasslands and low-elevation chaparral (e.g., the Rim fire of 2013 moved at less than 1 mile per hour on the fastest days, according to U.S. government data); so, with rare exceptions, wildlife has little difficulty moving out of the way while fires burn.
Photo: US Forest Service.
Among the first to arrive after a large fire are the wood-boring beetles, who intently seek out heavily burned forests with specialized sensory organs that detect heat and smoke from miles away. They flock to the smoldering forest to lay their eggs on the bark of scorched trees—the more burned, the better. The eggs hatch into grubs (larvae) that burrow beneath the bark and eat sapwood for a few years before burrowing out again and flying off as adults.
This super-abundant food source hidden in the burned trees attracts a variety of woodpecker species. The woodpeckers, balanced upright on tree trunks, using their specialized stiff tails, can hear the grubs moving under the bark. The woodpecker excavates a hole, pokes in its long, barbed tongue, hooking the grub, and pulls out a protein-rich meal, employing skills that would make any fly fisher envious. With reinforced skulls and ribs, and chisel-like beaks, woodpeckers—aptly called carpentero in Spanish—are perfectly adapted for excavating nesting cavities in hard dead trees, raising their young deep inside the safe, strong holes. Other kinds of cavity-nesting birds, from bluebirds to house wrens, as well as bats and other denning mammals, cannot excavate these holes, so they take over this prime real estate after the woodpeckers have departed. The combination of so many available cavities in the dead trees (thanks to the woodpeckers), the shelter of fallen logs, the super-abundance of insects drawn to the burst of new flowers and shrubs, and nutritious leaves and seeds from post-fire shrubs, is why so many different kinds of wildlife thrive in forests after a large, intense fire.
The best-adapted woodpecker in the world for excavating into freshly fire-killed trees is the Black-backed Woodpecker, whose black back camouflages the bird as it perches on scorched tree trunks. This rare woodpecker is found almost exclusively, and reproduces most successfully, in the areas heavily burned in large fires. As pointed out by pre-eminent ornithologist Richard Hutto, this bird simply would not have evolved as it did without the presence of large areas of regularly occurring intense fire throughout its evolutionary history—strong evidence for the naturalness of big fires in western North America. This bird is profoundly harmed by fire suppression, and the widespread practice of logging dead trees after a fire, so much so that it is now under consideration for listing under the Endangered Species Act.
Many media stories describe the forest after a large fire as a ‘moonscape’ in desperate need of ‘restoration.’ One Forest Service spokesman recently described last year’s large Rim Fire that burned in the Sierra Nevada as “nuked.” Nothing could be further from the truth. In western North America, where large, intense forest fire is natural, shrubs and trees have evolved the ability re-sprout from their roots and trunks, and some have seeds that germinate best only after intense fire. Many fire-following shrubs fix nitrogen in soils, allowing nitrogen-hungry conifers and other plants to flourish during natural regeneration. Flowers bloom, mushrooms thrive, insects buzz, squirrels and mice feast on seeds, woodpeckers and flycatchers abound, a symphony of birdsong echoes. Even a creature synonymous with old-growth forests, the iconic Spotted Owl, takes advantage of intensely burned forests to hunt for gophers and woodrats. A unique, fascinating, complex, life-filled world can be found in the days, months, and years after a large forest fire. In fact, the habitat created by large, intense fires supports levels of native biodiversity and wildlife abundance that are comparable to, or higher than, old-growth forests. So why be distressed when such a fire happens? Why aren’t we celebrating, breaking out binoculars to go birding, packing up wildflower guides to identify the flowering plants, or slinging on baskets to collect the prodigious morel mushrooms? And why would we ever consider logging in this ecological treasure trove?
The answer is there are powerful economic forces at work, with profits reaped from logging in the name of fire. Logging is proposed as a solution to preventing future fire and to ‘restoring’ green forests after fire. Many within federal and state land-management agencies, Congress, private industry, and even a few conservation groups promote logging out of fire phobia and economic interest. Consider this fact – according to the Office of Policy and Analysis, annual fire suppression costs on public lands in some years now exceeds $4 billion, and ‘fuel reduction’ (logging in the name of fire protection) costs taxpayers hundreds of millions of dollars annually through the Forest Service alone. In big fire years, the Forest Service also proposes millions of dollars in post-fire timber sales on federal public lands while Congress pushes legislation to bypass environmental review to quickly cut burned trees before they lose their economic value.
With massive expenditures in fire suppression, logging in the name of fire prevention, and post-fire timber sales, fire is big business. This situation creates an inherent conflict of interest for the agency. As the U.S. 9th Circuit Court explained in a 2006 ruling against a Forest Service post-fire logging project, “it has not escaped our notice that the Forest Service has a substantial financial interest in the harvesting of timber in the National Forest. We regret to say that in this case, like the others just cited, the Forest Service appears to have been more interested in harvesting timber than in complying with our environmental laws.”
Fire phobia promotes fire as the enemy, and fear is an understandable reaction after a half-century of Smokey Bear and witnessing firefighters attacking blazes with aircraft and chainsaws amid warlike rhetoric. Yes, human structures in fire-prone forests are at risk if they are not built and maintained properly, and yes, a blackened swath of dead trees may not look like what we have come to believe a forest should look like, but the truth is that we have nothing to fear from large fires in the forest. Ignition-resistant construction and removing adjacent vegetation nearest homes is the only way to prevent loss of life and property from forest fires, while logging the forest before or after a fire is unnecessary, expensive, and extremely damaging.
We often hear the claim that logging is necessary to clear dense, overcrowded forests of dangerous ‘fuels.’ In this way old-fashioned logging is repackaged as ‘fuels reduction,’ but this simplifies complex forests to just one aspect: their ability to burn. So-called ‘fuels’ are trees and shrubs that stabilize soils and provide shelter and food for a host of forest-dwelling creatures. Because climate and weather are the real drivers of fire behavior, logging trees and clearing shrubs in ‘fuels reduction’ does little to influence the behavior of large fires during extreme weather events. We also hear the claim that logging and replanting after a large fire will restore the forest, otherwise the area will remain a shrubfield for decades. In fact, trees grow back better without human intervention, and in the meantime those temporary shrubfields intermixed with standing and fallen dead trees are favored habitat for many kinds of animals, and are part of the natural succession of forests after a fire. Numerous native birds are primarily dependent upon shrub habitat in intensely burned areas, and many of these are declining in population due to fire suppression and the widespread and expensive practice of eradicating shrubs after fire. As geneticist and author Spencer Wells noted, “more and more, we are realizing that tinkering with nature can produce unintended consequences.”
Speaking of tinkering with nature, many people are now invoking climate change as another justification for logging forests for fire prevention. What if fires get bigger and hotter in the face of climate change? Don’t we need to cut trees now to save our forests in the future? Widespread and effective fire suppression since World War II means forests now have too little fire, not too much fire. Even increased fire due to climate change is not likely to ameliorate this fire deficit. The fire deficit is so steep that even if the amount of fire in Sierra Nevada forests were to double from current levels, there would still be far less fire than existed prior to the era of suppression. Furthermore, as fires become increasingly governed by extreme weather events, fuels become less important to fire behavior. Thus, intelligent planning would limit sprawl into fire-prone areas and reduce fuels near existing homes.
Finally, let’s remember that the many plants and animals that require large, intense fires to thrive aren’t the only organisms to co-evolve with large fire. For millennia, Native Americans maintained a respected kinship with forest fire. Late 19th century Euro-American colonization, and its doctrine of dominion, ruptured this age-old kinship between people and fire. We propose a paradigm shift away from fire phobia, and to an admiration of large fire’s ecological benefits. With all of the fear-mongering around large fire being encouraged by logging interests, this is no easy task. But when we summon the courage to move past our fear and learn the truth about fire ecology, we will then be on the right path to living in harmony with our naturally beautiful, fire-adapted forests.
Monica L. Bond is a founder and Principal Scientist at the Wild Nature Institute.
Chad T. Hanson is a forest and fire ecologist with the John Muir Project of Earth Island Institute.
Dominick A. DellaSala is Chief Scientist with the Geos Institute. Collectively the authors have published dozens of peer-reviewed scientific articles on fire ecology, and are nationally recognized experts on the topic.