Rebuilding Sonoma County: Using fire as a tool to prevent disasters

It has long been gospel that it takes fire to fight fire - wildfires, specifically.

Burning out brush that would otherwise feed encroaching wildfire is a highly effective practice, and often is the only way to gain control of a big blaze.

But fire also can be used as a preventive measure, a means of avoiding catastrophic wildfires. By burning out heavy vegetation and dead wood under ideal conditions - low wind, relatively high humidity and low temperatures - the destructive force of any eventual wildfire can be minimized.

Such so-called prescribed burning is a standard tool for wildland management agencies. When employed on a landscape scale, wildfire risk over large and remote areas can be reduced. Moreover, there are significant environmental benefits. Burning out brush, downed wood and thick stands of saplings returns nutrients to the soil in the form of ashes, kills insect pests, improves growing conditions for older, larger trees and can even improve stream and spring flows. Also, California’s wild ecosystems evolved with wildfire. Many of the state’s native plants need periodic low-level fires to thrive, or even reproduce. Some trees and shrubs are “serotinous,” meaning they require fire to develop or release their seeds.

But national forests are one thing, and populated areas with a mix of forests, homes and agricultural lands are another.

The North Bay fires were driven by three primary factors: heavy winds, low humidity and heavy wildland fuels. If any one of those three components had been eliminated or reduced, the destruction would’ve been reduced immensely.

There’s nothing that can be done about the weather, but fuels are another matter. So should we ramp up prescribed fire for so-called “interface” areas where development meets the wild lands?

As with many endeavors, it’s all about location, said Ben Nicholls, Cal Fire’s pre-fire division chief for Sonoma, Lake and Napa counties.

“Wildfire prevention needs to be considered as a layered defense,” says Nicholls, “so from that aspect, prescribed burning is best used on a landscape scale.”

Why? Because even a prescribed burn is, technically, a wildfire. Fire can escape established fire lines. That’s not a big deal in a national forest, where the burn may be miles from the nearest structure. But it’s another matter entirely if a burn is contemplated near a luxury home development on a hillside. A modest breakout that would only scorch a few trees in a remote stand of conifers could destroy several homes in an interface area.

For effective wildfire prevention, said Nicholls, homeowners must take direct responsibility for the areas around their homes. That means removing or at least greatly reducing flammable vegetation within a 100-foot radius.

Beyond that perimeter, Nicholls said, community or state agencies can create shaded fuel-breaks. These are relatively wide swaths of forested land along roads or around developed areas that have been thinned. Such fuel breaks typically are wooded, but the trees are widely separated and the forest floor is cleared of wood detritus. Trees and branches cut during the thinning process can either be chipped on site or stacked into “slash” piles and burned when temperature and humidity is optimal.

“Shaded fuel breaks interfere with the fuel ladder, the flammable vegetation from the forest floor to the tops of the trees,” said Nicholls. “They help protect communities from fires coming in, and they also have the added benefit of serving as fire lines for possible prescribed burns in wildland areas beyond developed zones.”

There are a couple of caveats about shaded fuel breaks, though: it takes a lot of time and labor to create them, and they’re not a one-shot deal. Eleven state Department of Corrections hand crews have been cutting fuel breaks in Cal Fire’s Sonoma-Lake-Napa unit, said Nicholls. But that’s not a lot of manpower, given the unit comprises 2 million acres. Plus, the crews are short-handed, Nicholls said, and the situation is unlikely to improve anytime soon.

“With mandated reductions in prison populations, we’re losing the (minimum security) inmates who can do this kind of work,” Nicholls said. “Also, you can’t just go in and cut a fuel break and walk away. You have to go back in every five years or so and maintain it. That requires a significant and long-term commitment.”

Spencer Andreis, a battalion chief for the Sonoma Valley Fire and Rescue Authority, said prescribed fires yield significant benefits both in terms of reduced wildfire risk and healthier wildland ecosystems. But local fire agencies don’t have the resources necessary for ambitious and safe prescribed burning, he said.

“We’ve assisted Cal Fire with prescribed burns in our area, but they’ve been minor projects,” Andreis said. “Prescribed burning in interface areas is complex and difficult. It can be very challenging. It’s not just the risk (to homes) from the fire itself. Air quality is also a critical factor. Even controlled burns put up a lot of smoke, and if the wind shifts unexpectedly, it can affect large numbers of people who have respiratory issues. You really have to take the public health issues into account.”

In many cases, said Andreis, mechanical methods are a safer if generally more expensive way to reduce fuels in urban interfaces. Such approaches involve removing vegetation by hand or heavy equipment, and then chipping the material.

“You target someplace that could really benefit from breaking up the fuel ladder but is probably restricted in area, such as a development located at the top of a ridgeline,” said Andreis. “But again, you have to remember that any benefit you get is temporary. Fuel breaks remove some of the risk for a while, but grasses grow back each year, and brush and timber return in a few years. Long-term protection requires long-term commitment to funding and crews.”

Perspectives can differ to some degree among different agencies. Scott Westrope, a deputy fire chief for the Santa Rosa Fire Department, generally is dubious about the value of prescribed fire on urban edges.

“In any prescribed firing operation, the conditions must be ideal to ensure safety and control,” Westrope said in an email response to questions. “Fuel and weather conditions need to be aligned to balance complete consumption of unwanted fuels, while maintaining the ability to control the burn. That being said, even in ideal conditions, we do not feel that prescribed burns are the most appropriate method of vegetation management in our suburban wildland interface and intermix. The Santa Rosa Fire Department supports mechanical and manual vegetation management as the safest, most controllable and environmentally protective means of risk reduction.”

In any case, prescribed burning isn’t a panacea. It may reduce risk, but it won’t eliminate it. And that’s especially the case with extreme weather conditions, such as those that characterized the North Bay fires.

“We have to remember that nature can trump you,” said Andreis. “Say there’s a development adjacent to a 300-acre area that had been treated with prescribed fire. There’s still going to be extreme risk to those homes if you have 70 mph winds pushing a fire, as we saw in the North Bay last year. When you have fires spotting a mile or more ahead of the main fire, any (precautionary) measure you took may be inadequate.”

Nicholls said prescribed fire is a necessary tool for appropriate areas “because there will be fire on the landscape.”

“We can introduce fire at a time that suits us, when it burns with low intensity,” he said. “Or fire can occur in late summer or fall with dry fuels and strong offshore winds, destroying thousands of homes and turning everything into a moonscape. The biggie that I want to put out there is that there is no single tool for all the jobs. Property owners need to harden their homes and properly maintain defensible space. Beyond that, we need to reduce fuels through mechanical means or prescribed fire. People always think fire happens somewhere else, but it inevitably touches every community. It’s a matter of when, not if.”