Monday, August 21, 2006

Wildfire Damage In The Desert

The recent desert wildfires in Southern California hit vegetation that rarely burns. Recovery may be a long, long time in coming:
More than 90% of the surrounding Pipes Canyon Preserve was consumed in last month's Sawtooth blaze. It was one of half a dozen fast-moving fires this summer that burned 65,000 acres of the Mojave Desert, fueling debate over whether the desert is burning more frequently and explosively as a result of invasive weeds, smog, development and climate change.

"It's heartbreaking to see," said Sall, a biologist who manages the preserve and whose grandmother homesteaded the land a century ago. "We'll never see those piñon or juniper trees again in our lifetimes, nor will our children, nor will their grandchildren. It's a bitter pill…. This land isn't meant to burn."

..."Right now we're losing very large pieces of landscape," said Todd Esque, an ecologist with the U.S. Geological Survey in Henderson, Nev., who studies the cause and effect of fires in the desert. "It's happening in Joshua Tree National Park, it's happening in Mojave National Preserve … up in southwestern Utah … and in Arizona. We lost 750,000 acres of desert to fire in Nevada alone last summer."

This summer, five blazes have seared parts of Joshua Tree, where a fire only every few years was the norm for the last 50 years. Esque and other researchers say that unlike forests and chaparral, the sparsely vegetated desert is not meant to burn frequently. "The public has come to understand that fire is a necessary part of the life of forests," Esque said. "That is not the case with deserts. We have a major problem going on."

A vocal minority disagrees, contending there is no clear-cut evidence of far-reaching change. They blame this year's fires on bumper crops of wildflowers nourished by heavy spring rains two years ago. According to the theory, dried remnants of the prolific blooms fueled a 50,000-acre fire in the Mojave National Preserve last summer and in this year's conflagrations.

"The winter of 2004-05 was the wettest ever in 100 years of recorded data in the desert. We had a phenomenal crop of annual native wildflowers, and it was dry the next year and it stayed there," said Richard Minnich, a professor of Earth sciences at UC Riverside. "It's flash fuel of 1 to 2 tons per acre. What's really scary is, there's still a lot of it out there."

Scientists do agree that it will take centuries, if not millenniums, for the desert to recover.

...At the scene of a 1995 fire, not a single juniper or piñon pine seedling has come up after 11 years. But healthy, 3-foot "pups" have sprouted from the roots of once seemingly dead Joshua trees. The pups may or may not survive, scientists say, because in drought years they may be gnawed by thirsty rodents and ground squirrels. Meanwhile, native apricot mallow, bright-green cheesebush and golden California marigold are blooming even in August.

...Webb is writing a paper with other researchers that looks at three post-fire scenarios for the Mojave, all plausible, all different. Rather than focusing on Joshua trees or pines, they studied ancient black brush, a gray-brown shrub that has evolved to withstand desert temperatures and scarce rain.

A single bush can survive thousands of years. But it is highly flammable, proof to Webb that fire is not natural in the desert. One scenario does show nonnatives replacing black brush and causing more frequent fires. But he said data gathered so far made that scenario "only slightly more likely" than two others in which black brush grows back. "Some of those Joshua trees may sprout too," Wall said, referring to the Pipes Canyon Preserve. "They're an amazing tree."

But others say such a destructive fire in a preserve like Pipes Canyon did lasting harm. ...Scott said there were probably smaller pockets of plants and animals that evolved over millenniums in nooks in the preserve, only to be wiped out by this summer's catastrophic fire.

..."What will be the one thing that does in the desert as we know it? It's not one thing. It's the onslaught of all these things," Esque said. He said there was little that could be done to turn back the clock. Many nonnative weeds are too far spread to be dug out, while native seeds are not widely available and can cost millions of dollars to gather and plant.

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