Recently I was wandering through a burnt forest in the aftermath of a wildfire with a mixed group of people as part of a field trip with a forest collaborative. We were examining the burn severity pattern that a recent wildfire had carved through the forest. In many places, the fire had barely charred the ground, while in other places nearly all the trees had been killed.
Standing among the black snags that were created in the aftermath of a particularly high severity burn, someone asked how long it would take for the forest to “recover.” That is a common question I hear frequently from people, and certainly that is the way most people view the aftermath of wildfires. When they ask how long it will take to “recover” from the fire, they mean, how long will it take for tall, green trees to repopulate the area.
Though it is nearly universal among most people who have been taught to think about wildfires as “destructive”, from an ecological perspective it belies a failure to really understand forest ecology. It is the wrong question and certainly the wrong perspective to hold.
Green trees are only one part of a forest ecosystem life cycle, just as the river channel is only one part of a river system. Burnt forests are as important to forest ecosystems as flood plains are to river systems. Just as floods rejuvenate a river changing river channels, creating new habitat for colonizing plants like cottonwood and willow, and high flows allow some fish and aquatic organisms to migrate and move through the river system, wildfires also create important habitat and opportunities within forested ecosystems.
A “healthy” river is one that periodically floods. Among most western ecosystems, a “healthy” forest is one that periodically burns. Just as the intensity of floods can vary over time—with annual, 100 year and 500 year floods, the intensity and frequency of wildfires also varies depending on many factors including the species of plants living in a site, climatic changes, and so forth.
The burnt snags and blackened ground we were walking through were not “recovering’ from the fire. Rather the burnt forest with its snags, open soils, and flood of nutrients was “recovering” from the green forest. Wildfires are the major recruitment mechanism for creation of standing snags and fallen logs. And these are critical elements in most forest ecosystems.
If you are a wood boring insect, you love the blackened snags—and if you are a black-backed woodpecker you find a virtual smorgasbord among the snags. If you are a cavity nesting bird like the western bluebird or tree swallow than the burnt forest represents an abundance of new residential real estate.If you are a spotted owl, you hunt among the snags for the rodents that proliferate due to new seed producing shrubs, flowers and grasses. And among the charred snags, elk will find abundant forage on the invigorated new growth of shrubs and grass.
As these snags fall to the ground, they are invaded by wood-living bees and wasps that will pollinate the new shrubs and wildflowers that burst into color in the aftermath of a fire. The fallen logs will be colonized by yet other life forms from fungi to lichens and provide the home for small rodents. Dead logs become hiding cover and travel pathways for marten, fisher, and lynx.
It is for these and many other reasons that burnt forests have the second highest biodiversity after old growth forests, and are the only habitat for some species. Given that the snag forests that result in the aftermath of a forest fire are temporally and spatially rare—there is nearly always more green forest than fire killed forests on the landscape at any one time—these fire-dependent and fire created ecosystems are actually more rare than almost any other kind of habitat.
Words are important because they shape the way we perceive things. That is why to suggest that the forest is “recovering” from a wildfire implies a failure to appreciate the ecosystem’s needs. At least in most western forest ecosystems, a “healthy” forest is one that burns. Indeed, after fire, we might be more ecologically correct and truthful if we said the forest ecosystem is recovering from the green forest.
George Wuerthner has published 36 books including Wildfire: A Century of Failed Forest Policy.