Vicious cycle of frequent fires is remaking Southern California's ecology

Vicious cycle of frequent fires is remaking Southern California’s ecology

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A Chula Vista firefighter walks away from the Harris fire in San Diego County in October. Scientists worry that native coastal sage and chaparral may be replaced by invasive grasses in areas that burned in 2003 and again last year. (Brian van der Brug / Los Angeles Times)

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Tom Warren walks through fire-scarred land near Midas, Nev., that was replanted with grasses and sagebrush. (Brian van der Brug / Los Angeles Times)

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Jon Griggs, manager of the Maggie Creek Ranch in northeast Nevada, looks over a 400-acre area that was reseeded after a recent fire. Winds blew most of the seeds away before they could germinate. (Brian van der Brug / Los Angeles Times)

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Invasive cheatgrass covers a hillside in northern Nevada, where repeated fires have wiped out native sagebrush, visible in the foreground. (Brian van der Brug / Los Angeles Times)

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Mike Pellant, coordinator of the Great Basin Restoration Initiative, holds a fist-full of cheatgrass in Idaho. (Brian van der Brug / Los Angeles Times)

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Federal research ecologist Susan Meyer holds a Petri dish growing a naturally occurring fungus that inhibits cheatgrass germination. She calls it “the black fingers of death.” (Brian van der Brug / Los Angeles Times)

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Mike Pellant of the U.S. Bureau of Land Management on a cheatgrass-choked hillside in the Snake River Birds of Prey National Conservation Area in Idaho. (Brian van der Brug / Los Angeles Times)

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Federal researcher Jon Keeley at Box Springs Mountain Reserve in Riverside County. Frequent fires have destroyed the native shrubs on the hillsides, which are now covered with invasive grasses. (Brian van der Brug / Los Angeles Times)

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Jon Griggs, manager of a ranch near Elko, Nev., walks through an area swept clean of sagebrush by recent fires. About 80% of the ranch’s grazing land has burned in the last two years, he says. (Brian van der Brug / Los Angeles Times)

By Bettina Boxall

Aug. 2, 2008 12 AM PT

Los Angeles Times Staff Writer

Jon Keeley is standing on a dirt road in western Riverside County, looking out across the Box Springs Mountains. Instead of a thick coat of native shrubs, the slopes are covered with a shriveled tangle of mustard, wild oats and red brome.

Too much fire is the culprit.

Since 1957, there have been 33 fires larger than 100 acres in the Box Springs -- more than the area’s native coastal sage and chaparral could withstand.

“Scenes like this you can see all over Southern California,” says Keeley, a research scientist for the U.S. Geological Survey.

Chaparral is accustomed to intense, periodic wildfire. But as Southern California’s population has increased, so has the frequency of wildfires, most of which are caused by people. Shrub lands that used to burn every 50 to 150 years on the coast and every 30 to 100 years inland are burning far more frequently in some areas.

The chaparral and coastal sage don’t have time to regrow before the next inferno. Hillsides turn into ugly outposts of invasive weeds.

The transformation is impoverishing the biological community. Some species, such as coyotes, will do fine. Those that need a more complex habitat, such as bobcats and the coast horned lizard, won’t.

“We can go to places that are invasive grasslands now that are missing a lot of species,” said Robert Fisher, a USGS research biologist in San Diego.

The change in vegetation extends the fire season because many invasive plants burn virtually year-round. Toss a cigarette into a stand of coastal sage in June and in most years it won’t ignite. Do the same to a bed of red brome and it will.

And grasses don’t hold the soil or water as well as deep-rooted shrubs, leaving hillsides more prone to landslides and erosion.

In time, Keeley said, most of Southern California’s wildlands could look like the Box Springs Mountains, largely bereft of their signature stands of chamise, manzanita and California buckwheat.

“We could lose it all.”

bettina.boxall@latimes.com

Vicious cycle of frequent fires is remaking Southern California’s ecology

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