In my previous post I described just how vital fire is to California’s ecosystems. Periodic fire is necessary for the maintenance of native California flora and fauna. Fire is a part of the habitat itself. So what happens if we exclude fire from an area? Americans have unwittingly subjected the American West to this experiment for over 150 years.
Most of us are familiar with the tragic displacement of Native Americans by Western settlers as the United States pushed across the continent. This human tragedy resulted in an ecological tragedy as well. The new dominant culture was one that greatly feared fire. In California's dry forests, a single fire could wipe out entire towns in the blink of an eye. As a Spotted Owl Technician for the U.S. Forest Service, I reported to a workstation in Camptonville, CA, a town whose history includes two fires that burned it to the ground. Early American settlers had a very good reason to fear fire.
Predictably, firefighting services developed before the study of ecology did. Early firefighters operated under the grossly incorrect assumption that any fire is a bad fire. This is easy to understand. Fires are associated with loss of life, property, and livelihood. To let a fire burn unchallenged would have seemed insane! Rather than putting out only the fires that put human structures in danger, these firefighting services would jump on any incident at the first sign of smoke.
The policy of total fire suppression established by local and federal firefighting agencies dramatically reduced the frequency of fire in California and the West, hijacking the natural processes necessary to keep forests and other landscapes in ecological balance. In the absence of fire, the buildup of dead plant matter and other debris continued for decades. Weak and diseased trees were no longer weeded out of the landscape, creating a forest much more densely populated with trees. Water, sunlight, soil nutrients, and space to grow all became scarce, leading to intense competition for these resources. Areas that once were sprinkled with tall, wide trees now held bloated populations of thinner trees ill-prepared for a fire. The natural fire-breaks created by past burns began to fill in, often with invasive trees not adapted to fire. Just as a fire-adapted people were driven out by a fire-fearing people, tree species that were made rare in the presence of fire became dominant in its absence.
Grazing and logging played also played a role in the transformation of California forests. Livestock animals began to graze on the same grasses that would burn “cool” and carry fires across great distances on a fuel-reducing mission. In its earliest stages, logging was similarly devoid of ecological considerations; the large, fire-resistant trees were the first to be targeted and harvested. Roads, both paved and unpaved, similarly limited the grass fires’ ability to spread and reduce fuels. Ironically, if cool grass fires can’t spread, catastrophic fires capable of jumping roads will spread.
While grazing removed the fire-carrying grasses, it didn’t remove the buildup of other vegetation that couldn’t be grazed. Thick woody shrubs would grow, die, and dry, but not burn away. These shrubs, along with standing dead trees, are known as ladder fuels. Ladder fuels carry a fire from the forest floor vertically into the forest’s canopy, into the crowns of the trees. Whereas the trunks of these trees had developed defenses to fire, the crowns are much more susceptible to flames. Thus, crown fires can indiscriminately burn trees from the top down, spreading from treetop to treetop. Once a fire leaves the forest floor, the plethora of combustible fuels found higher up the trees allows these fires to burn hotter and more intensely, which ultimately makes fuels more likely to burn. It is a vicious cycle.
Crown fires are not just vertical grass fires. They are another beast entirely.
In California and much of the western United States, crown fires are becoming increasingly common. Unintentionally, we have traded frequent, cool, surface fires for infrequent, devastating crown fires. Ecologically, this is not what most California forests and woodlands have adapted to endure. When the wrong type of fire hits an area, unprecedented ecological change inevitably results.
It is sadly ironic that our present circumstances were completely avoidable. Rather than cooperating with native cultures that understood fire, early US settlers chose to subjugate them. Had this grave moral mistake been avoided, these ecological repercussions, including the devastating fires of the last few years, may have turned out differently.
Stay tuned for Part 3, where we’ll go into detail on what these fires do to an area ecologically.
Barbour, Michael; Pavlik, Brucel Drysdale, Frank; and Lindstrom, Susan. 1993. California’s Changing Landscapes: Diversity and Conservation of California Vegetation. A publication of the California Native Plant Society.
Forestry Institute for Teachers. Personal Correspondence. July 2016.
Hessburg, Paul. Living (Dangerously) in an Era of Megafires. TEDx Bend, Oregon. 2017. https://www.youtube.com/watch?v=edDZNkm8Mas
Kramer, Heather et al. Estimating Ladder Fuels: A New Approach
Combining Field Photography with LiDAR. Remote Sensing. 2016. https://www.fs.fed.us/psw/publications/lake/psw_2016_lake001_kramer.pdf
Public Broadcasting Service. Fighting Wildfires. 2015.
Schnepf, C. Fire Behavior Basics. Oregon State University. 2017. https://ir.library.oregonstate.edu/downloads/qr46r108p
Wikipedia. Carr Fire. 2018. https://en.wikipedia.org/wiki/Carr_Fire#/media/File:2018_Carr_Fire_(42286511740).jpg