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Historical Wildfire in California

Updated: Nov 4, 2018

On July 23rd, 2018, an RV with a flat tire sent a spark into the roadside brush in Whiskeytown National Recreation Area. That spark began what is now known as the Carr fire. Ultimately, the Carr fire burned nearly 230,000 acres of land and destroyed over 1,500 buildings in the Redding, CA area, including nearly 1,100 residences. Eight people lost their lives responding to or fleeing from the fire. The outcome of that spark did not have to be the tragedy we find ourselves recovering from. Join the Home Sweet Habitat team as we explore fire in the context of habitats. This is part 1.


What Did Fire in California Look Like Historically?


Wildfire is inevitable in California. This is not a bad thing. In fact, this is a good, life-giving thing. Without wildfire, California would not be the beautiful, biologically diverse playground that we know and love today. Yet the fires we have been seeing in our beloved state in recent years are far from normal. A combination of factors have contributed to the rise of the fires we see today. To really understand just how unnatural these fires are, we need to go back to before gold was discovered at Sutter’s mill.


Imagine California before western settlers flooded the scene and established a fire regime that better suited their preferences. You would be surprised as you looked around. Forests were much thinner overall, with some areas remarkably bare. In fact, a stark contrast can be found between photographs of the same forested areas a century apart.


Forests were less monotonous. Due to varying conditions in micro-climates such as precipitation levels, temperatures, and fuel loads, fires would burn different areas differently. An area that experienced a high level of precipitation could build up brush and other fire-starting fuels for several decades. When it finally encountered fire-conducive dry conditions, the area would burn intensely, clearing the forest of most or all of its trees. This was not the norm, however. Fires generally burned through any given area about once every 10 years, leaving the forests open with natural fire breaks. In fact, the Native American peoples that previously dictated California’s fire regime worked with ecology rather than against it, setting small fires to clear vegetation and promote new growth.


As far as my research has found, there are no records of a Native American “prescribed burn” going awry and creating tragedy. The thinner forests did not carry fire like they do today. Whether by lightning strike, spontaneous combustion, or by human hands, the fires would burn low and “cool” through the landscape. These surface fires mostly burned dead and fire-prone grasses, shrubs, and other vegetation. Some trees would burn, but these were usually very young, very weak, or diseased trees. The rest of the trees (if properly adapted) would survive with merely a scar to show for it.


The roughly decadal cycle of California forest fire is well-established by our studies of tree rings, called dendrochronology. Fire scars persist in the tree rings, and we can read past fire history like an open book. So what of these trees that survived? They grew tall and wide, unhindered by fierce competition with neighboring trees for sunlight, water, and nutrients. This only made them stronger when the next fire hit. Before 1849, forests were thinly populated with tough trees that a grass fire could not seriously harm. Surface fires stayed surface fires.


Most California forest vegetation can’t just withstand fire; they need it. Many California conifers (cone-bearing trees) have serotinous cones that only open under the intense heat of fire. This ensures that their seeds only reach the ground after competing vegetation has been burned, providing nutrient-rich soil and room to grow. The Baker cypress below is one example:



On the other hand, some areas of California rely on infrequent, intense fire. In California’s chaparral ecosystems, species of Ceanothus and Manzanita produce extremely volatile oils that ignite quite easily and encourage the fire to reach temperatures that can melt aluminum. The existing shrubs perish in the fire, but this ultimate parental sacrifice clears vegetation and provides nutrient-rich ashy soil for dormant seeds. Buried a mere 3 inches beneath the ground, a 3,000 °F fire heats them up to a mere 150 °F, just enough to stimulate their germination. While this is a remarkable feat of ecology, it would also do well for us to restrict our development in these areas, but that’s another blog post entirely.


The Manzanita shrubs dominating this landscape produce combustible oils that encourage fire to burn more intensely.

California’s fire regime began to change with the influx of settlers, especially after the gold rush. A new people brought with it a new culture, one that was terrified of fire. This fear led to fire suppression, which led to—ironically—more fire.


Stay tuned for part 2: How California’s Fire Ecology was Hijacked

Sources:


Barbour, Michael; Pavlik, Bruce; Drysdale, Frank; and Lindstrom, Susan. 1993. California’s Changing Landscapes: Diversity and Conservation of California Vegetation. A publication of the California Native Plant Society.


California Department of Forestry and Fire Protection. 2018. Carr Fire Incident Information. http://www.fire.ca.gov/current_incidents/incidentdetails/Index/2164


Paul Hessberg. Living (Dangerously) in an Era of Megafires. TEDx Bend, Oregon. 2017. https://www.youtube.com/watch?v=edDZNkm8Mas


Personal correspondence: Forestry Institute for Teachers. July 2016.


United States Forest Service. 2018. Fire Effects Information System. Arctostaphylos manzanita. https://www.fs.fed.us/database/feis/plants/shrub/arcman/all.html


United States Forest Service. 2018. Fire Effects Information System. Ceanothus foliosus.

https://www.fs.fed.us/database/feis/plants/shrub/ceafol/all.html

United States Forest Service. 2018. Fire Effects Information System. Ceanothus leucodermis.

https://www.fs.fed.us/database/feis/plants/shrub/cealeu/all.html#84

United States Forest Service. 2018. Fire Effects Information System. Hesperocyparis bakeri.

https://www.fs.fed.us/database/feis/plants/tree/hesbak/all.html

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