Drought, dead trees add up to big fire danger for California

Trevor Galeazzi and other Cal Fire engineers clear dead grass to help protect a community near Santa Rosa. Trevor Galeazzi and other Cal Fire engineers clear dead grass to help protect a community near Santa Rosa. Photo: Leah Millis, The Chronicle Buy photo Photo: Leah Millis, The Chronicle Image 1 of / 10 Caption Close Drought, dead trees add up to big fire danger for California 1 / 10 Back to Gallery

Stubborn drought conditions and an epidemic of dead and dying trees mean California is facing a potentially catastrophic fire season, federal officials said Tuesday as they promised to send extra money and personnel to the state.

Similar circumstances contributed to record acreage lost to wildfires in the West last year, including three blazes that laid waste to Lake County, and top officials at the U.S. Department of Agriculture said improved rain and snow totals during the winter did little to ease the threat.

Four straight dry winters before this one wiped out sugar pines, cedars and oaks throughout the Sierra and other mountains in California, Agriculture Secretary Tom Vilsack said during a briefing on the fire season in Washington, D.C.

“You’ve got 40 million dead trees. You’ve got 40 million opportunities for fire,” Vilsack said. “You’re looking at a very serious situation.”

High fire potential

The latest report from the National Interagency Fire Center, a collective of firefighting agencies, shows high fire potential for Southern California, the southern and central Sierra, and the foothills of the Sacramento Valley through the forecasting period of July and August.

The Agriculture Department, which oversees the U.S. Forest Service and that agency’s large firefighting force, has committed $30 million to California. That will help pay for clearing dead trees along roads, outside rural communities and near campgrounds, where fire danger is greatest, Vilsack said.

To date, 65,000 trees have been removed by federal and state personnel.

Meanwhile, the California Department of Forestry and Fire Prevention, which manages the state’s firefighting crews, has ramped up staffing earlier in the season for the second year in a row. Extra firefighters tended engines statewide all through winter, and seasonal hiring accelerated in February.

“Now they’re ready to go,” said Cal Fire spokesman Daniel Berlant. “We’re already starting to see the grass in the central Sierra (and) the Central Coast all the way down to Southern California begin to brown.”

Cal Fire has responded to 931 fires since the start of the year, mostly small blazes that weren’t fanned by summer heat and drier fuels. Although that’s fewer than the roughly 1,200 fires at this point last year, it is still high considering the crux of the season is a long way off, Berlant said.

The vast stands of dead and dying trees, he added, are reason to think that fire danger could escalate more this year than in the past.

“No level of rain is going to bring the dead trees back,” Berlant said. “We’re talking trees that are decades old that are now dead. Those larger trees are going to burn a lot hotter and a lot faster. We’re talking huge trees in mass quantity surrounding homes.”

Although the Forest Service counts 40 million dead trees, about 29 million of which died last year, a recent study by the Carnegie Institution for Science suggests that as many as 58 million trees are suffering severe water loss because of the drought. Most are outside Los Angeles and in the southern Sierra, but the Bay Area and North Coast are not without casualties.

The result is browning leaves and dying limbs, which weaken a tree and make it more susceptible to bark beetle infestation.

At least two to three years of average rainfall are needed to bring tree moisture levels back to normal, scientists estimate.

The forecast for a La Niña this fall or winter only adds to the concern. La Niña, which is the opposite climate pattern of El Niño and represents a cooling of the Pacific tropics, is sometimes associated with dry weather in California — though that trend is far from clear.

This winter’s El Niño contributed to moderately wet weather in California, particularly in the north, which helped mitigate the fire risk a bit.

Relief only temporary

But Forest Service Chief Tom Tidwell said Tuesday that the relief was temporary.

“What we saw this spring is that snowpack has come down faster than we’ve seen,” he said, noting that above-normal temperatures are quickly drying up the vegetation and that Southern California wildlands never saw much dampening in the first place. “We anticipate a very active fire season in California.”

The prognosis comes after a tough time for fires last year in the Golden State.

In October, the Valley Fire tore across 76,000 acres in Lake, Napa and Sonoma counties, killing four people and destroying more than 1,300 homes. The blaze, which followed two other wildfires in the area, was the third most destructive in California history.

Federal officials say wildfire danger nationwide has increased with climate change. Fire seasons have lengthened by an average of 78 days since 1970, and the average number of acres burned annually has doubled since 1980, they said.

Last year, a record 10.1 million acres burned nationwide.

Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: kurtisalexander