All his life, Thom Porter has seen the devastating effects of Southern California's particular brand of wildfire, whooshing across canyons fanned by the dreaded Santa Ana winds.
He's also seen flames stop short, stymied by something as simple as a dirt road or recently burned patch of earth, starved for lack of fuel.
To many firefighters like Porter, a fourth-generation San Diegan and chief of the San Diego County Fire Authority, and others who have been on the front lines, it's obvious: Areas that have burned recently are less likely to ignite, or will burn less intensely, while old-growth patches are primed to combust.
But what many firefighters believe they've learned from experience is the subject of much debate, as state officials search for a way to approach Southern California's large, unwieldy blazes.
Earlier this month, as the Silver fire raced past Cabazon in Riverside County, a group of state fire officials and fire scientists met in a Ventura County hotel ballroom to debate a sweeping proposal to govern how the state prevents fires on 38 million acres, more than a third of California's land area.
The proposed program, drafted by the California Department of Forestry and Fire Protection, relies on techniques such as controlled burns and mechanical clearing of brush, and highlights an ongoing clash between academic research and battle-tested strategies from firefighters on the ground.
Although Porter and other fire managers say stemming vegetation growth remains one of the most effective ways of avoiding out-of-control fires, critics say the state's proposal is based on an outdated approach to fire prevention and doesn't address the specific challenges posed by the region's chaparral-fueled fire disasters.
The state's proposal relies on what scientists refer to as the "mosaic model," which calls for burning or cutting down thick, old-growth plants to create a patchwork of ages in the vegetation. The patchwork, fire managers argue, makes for less intense fires and more protection against their spread.
Experts on both sides agree that for decades, the model has been used with great success in forests, where controlled burns on old underbrush have prevented wildfires from climbing to the tops of trees.
But the mosaic model crumbles in the dry, exposed chaparral and scrubland so pervasive in Southern California, fire science specialists say.
Chaparral fires burn hotter and more intensely than forest fires and more readily scatter embers and flames that consume plants both young and old. The fierce Santa Ana winds don't help.
These scientists maintain that the Silver fire is evidence that even new-growth chaparral in recently burned areas will burn again. One of the most destructive fires this year, it singed more than 20,000 acres and destroyed 26 homes, even though most of the area had burned seven years ago in the deadly Esperanza fire.
Just as the blaze seven years ago failed to prevent the spread of this month's fire, using controlled burns or bulldozers would have been similarly ineffective, critics of Cal Fire's approach say.
"There's just zero evidence that prescribed burns or fuel treatments have ever been effective in changing the fire behavior in Southern California chaparral," said Jon Keeley, a fire ecologist with the U.S. Geological Survey who has studied fires for more than 40 years.
Keeley and several other researchers have published studies rejecting the long-held assumption that age matters in chaparral fires, or that vegetation management helps beyond the immediate clearance around homes.
Porter disagrees, saying fuel breaks and treatments provide firefighters with areas of less intense flames, from which they can make a stand against the blaze.
"From a firefighter's perspective, you cannot fight fire as effectively in dense chaparral as you can in younger, reduced-volume chaparral," he said. Vegetation management "is just another tool. It's like a shovel or a bulldozer or an airplane."
He credits prescribed burns with shielding the Mt. Laguna and Pine Valley communities during the deadly 2003 Cedar fire in San Diego County, which to date remains the state's largest. Porter, who is also chief of Cal Fire's San Diego division and a strong proponent of fuel control, has overseen a robust program of vegetation treatment in the county.
"Unfortunately, the science has not kept up with the firefighters," Porter said.
Rick Halsey, executive director of the California Chaparral Institute, says focusing on fuels management doesn't work. "They're using the same strategies that haven't worked for decades, and they're still losing homes," Halsey said of firefighting agencies.
Rather, Halsey said, fire managers should focus resources on fire-resistant construction and improving clearance of defensible space around homes, two strategies that have helped save lives and property, he said.
According to Halsey and others, removing old vegetation far away from communities — a key element of the state plan — does little to lessen wildfire threat and degrades native chaparral habitats, allowing more flammable weeds and grasses to invade.
The state called for additional workshops to hear feedback on the plan after Halsey and others raised concerns that Cal Fire was using a "one-size-fits-all" approach statewide. Officials hope to conclude the environmental review process within six months and expect the new program to take effect in 2014.
State officials stress that only 200,000 acres per year would be subject to expanded vegetation management under the proposal and that local fire managers have always tailored firefighting principles to local conditions and terrain.
"We do things differently in different vegetation types, and obviously we didn't make that clear enough," said Russ Henly, assistant deputy director of resource protection for Cal Fire, adding that the agency is "taking a second look" at the mosaic issue. "We're not frozen here with respect to what we've put forward with this program … and we're open to making changes."
christine.maiduc@latimes.com
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