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Western wildfires: It’s all about the fuel

Before fire suppression, shrubs beneath this pine burned as seedlings, it may have had enough moisture to resist the beetles that killed it.
Before fire suppression, shrubs beneath this pine burned as seedlings, it may have had enough moisture to resist the beetles that killed it. TNS

In 1984, the ponderosa pine and oak forest around my new home was young second growth after logging in the early 20th century. By the time I moved away almost 20 years later those trees had literally doubled in height. One day we woke up to the realization that we wouldn’t survive a wildfire there. Knowing that the flame height is roughly three times the height of the plant, those forest trees had become a disaster waiting to happen.

It was going on everywhere so gradually that nobody noticed. Lots of new folks came to live in our tiny community so the population was rising. Not only was the forest growing, but the understory shrubs and poison oak beneath them became so dense as to be impenetrable. I knew that at the end of the summer, all it takes is a spark or a lightning strike or a car newly parked in dry grass to start a major conflagration.

The first fire was started by a homeless guy burning toilet paper in the wind. This fire resulted in 95 of my neighbors leaving. Two years later the same area burned again (elect fan sitting on clothing in an RV) and made everyone else leave. Since leaving there due to the immense fire hazard, Yuba County has suffered many more serious, damaging fires. This devastation in Napa and Sonoma Counties is directly related to this problem: failing to manage wildlands.

Living in these forests growing denser by the day you get the sense there is clearly a lack of concern for fuel buildups. These are fire prone ecosystems that once depended on burns to renew native shrubs and trees from the root crown. Without fire they become old and decadent and crowded. This also explains the beetle damage to pines as this natural mechanism thins out the weaker individuals in overly dense stands so those that remain have enough moisture to survive.

The big factor in California fires this year is the abundance of fine flashy fuels. Last winter’s heavy rains over a long period produced a bumper crop of volatile grass and weeds. In open spaces the new grass dries out by fall, just waiting for a spark to start a fast moving fire. Wildfire moves quickest in grasses because the fuel incinerates immediately. It was these grasses that Native Americans burned in the late summer to make acorn gathering easier around the large valley oaks.

The second factor is the impact of drought on trees and big shrubs. The whole state saw rigorous water restrictions for quite awhile and lots of folks have changed their landscaping to drier plants. Problem is the trees aren’t getting the water they used to deep down because what was there vanished during drought. Trees gradually lost hydrostatic pressure during the drought, then didn’t have time to recover enough before this fire season.

Keep in mind that trees have to take up enough water to get through today. If there isn’t enough extra in the soil to replace what was lost, lower internal moisture levels result. In time it resolves naturally but when fire strikes before there’s time for full rehydration of a forty foot tree, it becomes more flammable. Perhaps the trees in Santa Rosa weren’t completely rehydrated by last winter’s rain. This would make them far more vulnerable to a fast moving crown fire that jumps from tree to roof to tree just like a forest fire.

We notice the strong fire driving winds this year, but they’ve always been there. When they blow and there’s no fire, we just don’t remember them. It’s that one time when a transient decides to set toilet paper on fire that is the clincher. We can’t control the wind, and we can’t control people. What we can control is the fuel volumes in our wildlands.

We think our beautiful forests and woodlands are protected, but what I’ve seen is horribly overgrown. Most are tinder boxes.

The consequence of failing to address the fuel loads is now a matter of life and death. This raises the importance of having a better plan to use mechanical, hand labor, goats and other economically viable methods to thin our wildlands. Thinning young trees and the understory of our forests increases light, stimulates plant and animal diversity and allows hikers, first responders and wildlife better access. Above all, it’s our only hope to curb the inevitable firestorms to come.

Maureen Gilmer is an author, horticulturist and landscape designer. Learn more at www.MoPlants.com. Contact her at mogilmer@yahoo.com or P.O. Box 891, Morongo Valley, CA 92256.