In my previous post I described just how vital fire is to California’s ecosystems. Fire is a necessary facet in maintaining the right conditions for California flora and fauna. Fire is a part of the habitat itself. So what happens if we remove most or all fire from the area? Americans have unwittingly subjected the American West to this experiment for over 150 years.
We are all familiar with the tragic displacement of Native Americans as the United States pushed west. This human tragedy resulted in an ecological tragedy as well. The new dominant culture was one that greatly feared fire. In the frequently arid landscapes, a single fire could wipe out an entire town. 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. American settlers had a very good reason to fear fire.
Naturally, firefighting services developed before the study of ecology did. These firefighters operated under the 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 them burn 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. Camptonville would still have been fully protected with a less aggressive response.
The policies 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, buildup of dead plant matter and other debris was no longer limited. Weak and diseased trees were no longer weeded out of the landscape; this led to 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 and weaker trees. The natural fire-breaks created by past fires began to fill in, often with trees not adapted to fire. Tree species that were made rare in the presence of fire became dominant in its absence.
Grazing and logging played a role in this transformation too. 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 that can jump roads will spread.
While grazing removed the fire-carrying grasses, it didn’t remove the fuel buildup of other vegetation that couldn’t be grazed. Thick woody vegetation would grow and eventually die 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 (known as a surface fire) vertically into the forest’s canopies, known as the crowns of the trees. Whereas the trunks of these trees had adapted fire-resistant mechanisms, the crowns had little need to develop such protections, and this newly introduced threat was one few trees had any defense for. Crown fires can and do indiscriminately burn trees from the top down, and spread from treetop to treetop.
In California and much of the western United States, crown fires are now the norm. Ecologically, this is not what forests and woodlands have adapted to endure. These crown fires cause unprecedented ecological change to an area. Unintentionally, we have traded frequent, cool, surface fires for infrequent, devastating crown fires. 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