Frequent fires slow nature’s rebound time

Frequent fires slow nature’s rebound time

4 November 2007

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USA — Wildfires that tore through more than half a million acres in SouthernCalifornia have left hundreds of homes vulnerable to mudslides and may havewiped out critical habitat for fast-dwindling species, wildlife and emergencymanagement officials said.

Federal and local authorities are scrambling to stabilize hillsides beforewinter rain arrives, hoping to prevent landslides and ensure that silt and ashdo not further harm reservoirs, watersheds and bottomlands that shelter arroyotoads, songbirds and centuries-old coast live oaks.

“We’re pushing up against winter fast,” said Todd Ellsworth, a federalsoils scientist overseeing teams that fanned out across seven counties last weekto assess fire damage and the perils ahead. “Every one of these major burnareas is above homes; they are near many, many homes. Our top priority is tominimize threats to those communities.”

Five people died in a massive mudslide in San Bernardino County on Christmas Dayin 2003, two months after wildfires ravaged steep slopes above their churchcamp.

Water quality is also a concern. Destroyed home sites and drifting ash maycontain lead, copper or other toxic substances that can leach into creek beds orrunoff, killing wildlife and possibly contaminating municipal water supplies,said Ellsworth.

More than 20 small water systems in Los Angeles and San Diego counties whosecustomers include restaurants, mobile home parks and community centers, areunder mandatory orders to boil water because of wildfire damage and subsequentbacterial contamination, said California Department of Public Health spokeswomanLea Brooks.

San Diego water officials also fear that runoff from burned areas will cascadedown the denuded slopes above Hodges, Sutherland and Barrett reservoirs, wherefires burned nearly to shorelines. “Keep Out” signs are being postedto try to prevent off-road vehicle users and cyclists from breaking through thecrusty soil and creating gullies and ravines.

Although damage assessments are not complete, experts said the increasing rateof wildfires over the last several years has put enormous pressure on wildlifethat had already been pushed into smaller habitats by development.

The coastal cactus wren, a large songbird with a chortling call, and two rarespecies of butterfly appear to have lost their largest known populations in theWitch and Santiago fires. The cactus wren, which hunkers down rather than flyingaway during blazes, nests in mature, decades-old stands of prickly pear cactus.Many of those cactuses are now melted ruins.

The caterpillar of the Hermes copper butterfly lives in one kind of redberrybush that has been burned or bulldozed for development across much of San DiegoCounty. The Thorne’s hairstreak butterfly can survive only on the rare Tecatecypress tree, which needs flame to release its seeds but cannot withstandtoo-frequent fire. Many of those trees burned in the previous fires in the lastfive years. San Diego County wildlife staff said they believed some of thebutterfly populations had survived last month’s fires.

In addition, massive live oaks that had withstood centuries of flame and floodare toppling at an alarming rate in burned areas. Trish Smith, a biologist withthe Nature Conservancy, surveyed the skeletal, splayed remains of aonce-thriving oak woodland along Santiago Canyon Road in eastern Orange Countyon Wednesday. “This is bad,” she said. “These poor, poor oaks;they were probably 200 years old.”

The Santiago fire, which officials say was caused by arson, charred more than28,000 acres, including 90% of Limestone Canyon, which burned in a 1998 fire.That blaze had left many of the massive old trees with “heart rot” attheir base, diminishing their ability to resist subsequent spring floods andsevere drought.

“This fire will just exacerbate that,” Smith said. “A lot oftrees are splitting in two already and falling.”

Ecologists said that although Southern California landscapes have evolved toburn and flood, the greater frequency of fires and mudslides caused by humansdoes not allow the decades necessary for recovery of chaparral and riparianwoodlands.

“One of the greatest fire tragedies for nature has been the re-burning ofareas lost in 2003 . . . that had only just begun to recover,” said DavidHogan of the San Diego office of the Center for Biological Diversity. “Thismay be the last straw for many endangered species that have already suffered somuch habitat loss to development and overly frequent fire.”

The latest firestorms threaten to undo years of work spent cobbling togethernature preserves that protected mam- mal crossings, unique habitat and foodsources. Dick Bobertz, executive director of the San Dieguito River Park, saidthe Witch fire scorched 75% of the park’s 80,000-acre greenbelt and destroyedthe park headquarters.

Some populations of wildlife that suffered losses in the fire, such asjackrabbits, easily recover, biologists said. Other species, such as kangaroorats, which burrow underground to survive blazes, thrive in post-fire conditions.

But measures to save homeowners and roads from torrential mudslides can hampersome species’ recovery.

San Diego County water authority officials said they will reinforce hillsideswith hydro-seeding, a technique that blasts green seeds at embankments.Conservationists cringe, saying past efforts to plant fast-growing ground coverhave inadvertently introduced exotic, highly flammable grasses that replacednative growth used as forage and shelter by Southern California fauna. Thepractice can also leave behind thick mats of seed that keep native seeds fromgerminating.

While biologists sifted through ashy slopes last week, looking and listeninganxiously for signs of life, nervous residents peered up at charred hills andwondered what awaited them.

Poway city staffers last week said they probably would put down straw balesto stabilize the massive, burned hill behind the home of Kathy DeBolt, 42, anart broker who has lived on her small ranch at the end of a dirt road since1996.

DeBolt has seen city staff spray seed on hills in the past, “but it may notbe possible on that hill, it’s so steep” she said.

Orange County public works officials aren’t waiting for fed- eral burn teamsto finish their inspections. By midweek, truckers who had driven through thenight from Central California were already unloading thousands of bales of ricestraw for use along ravaged Santiago Canyon Road.

There are reasons for hope. Herds of deer and a male mountain lion have alreadybeen spotted in the area. Smith listened in vain for a pair of cactus wrensformerly living in a patch of prickly pear cactus on scorched Loma Ridge. Butshe spotted a Bewick’s wren in an unscathed lemonade berry bush. A fat ravenperched nearby, and a northern harrier and flock of turkey vultures circledoverhead.

“It’s good eating for them right now,” she said. “All the bushesthat didn’t burn are going to be loaded with birds.”

Glancing down, she pointed to stubby, brown bumps dotting the burned hillside.”Those are all native bunch grasses adapted to fire,” she said. “They’llbe blooming any second now.”

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