Sunday, July 24, 2005
Copyright © Las Vegas Review-Journal

Unwelcome Neighbors

Fire-adapted invasive weeds crowding out Mojave Desert's native plants

Conservationist John Hiatt examines a Mojave yucca plant last week that stands in an area blackened by the Goodsprings wildfire south of state Route 160 near Mount Potosi. Photo by Clint Karlsen. New growth sprouts from the center of a burned Virgin River encelia plant that was caught in the Goodsprings wildfire. Photo by Clint Karlsen. Charred yucca plants jut from the landscape last week in Red Rock Canyon National Conservation Area south of state Route 160. In contrast, the area in the background that burned about 15 years ago is nearly void of native yuccas. Photo by Clint Karlsen.

The green of new life has begun to sprout out of a few charred clumps of native plants that burned south of Red Rock Canyon in last month's Goodsprings wildfire.

Despite hope that some Mojave yuccas, Joshua trees, blackbrush, creosote and brittlebush will survive, their future looks bleak in a landscape dominated by more fire-adapted, non-native weeds with names like red brome, cheat grass and Sahara mustard.

"What happens is this area that burned will be at increased risk in the future because of flash-fire fuel," conservationist John Hiatt said last week.

On a visit to this blackened stretch of the 30,000-acre area that burned south of state Route 160, Hiatt said he fears that the Mojave Desert as he's known it will never be the same because of invasive weeds.

Over the years, as noxious weeds that thrive in arid climates elsewhere in the world have spread deeper into the Mojave, the size of burned areas has grown proportionately.

The scene last week where Hiatt plucked seed-packed, red brome stems from patches that had escaped the flames mirrors some 1,400 square miles across Southern Nevada that have been blackened by more than a dozen major wildfires sparked by lightning in the past four weeks.

"It will burn again before it gets back to a semblance of what it was," said Hiatt, conservation chairman of the Red Rock Audubon Society.

"It's not the Mojave as we've known it," he said, pointing to an area nearby that burned 15 years ago and is nearly void of yuccas and Joshua trees but is dotted with native desert almond, a hardy, fire-adapted shrub.

"You won't see yuccas, you won't see Joshua trees, you won't see cacti and you won't see wildflowers either because these non-native grasses will crowd them out," he said.

In the old burn area, the desert floor was growing thick with red brome and cheat grass.

In the new burn area nearby, Hiatt predicted there will be 10 times as much weed growth next spring when seeds buried in the soil and unharmed by the fire mature into plants.

Records show that the Bureau of Land Management spent $850,000 combating invasive plants in 1994 compared to $8.2 million in 2004. With those funds, the number of acres on which weed treatments were applied on public lands in Nevada jumped from 1,294 in 2000 to 10,989 three years later.

In all, there are 42 species of noxious weeds that are not native to the state, and Hiatt believes the list probably will grow based on what has happened so far.

He said cheat grass, for example, came to Washington state from Russia in wheat seeds in the 1870s and 1880s and has since invaded the Great Basin and now the Mojave Desert.

"With increased world travel ... stuff we never even thought of is going to get here," Hiatt said.

He said if the trend continues and more invasive plants take hold, then populations of native plants will be reduced to pockets in the desert before scientists can figure out how to reverse it.

"Nobody has any idea how to restore the Mojave," Hiatt said, adding that the answers can only be learned through research.

But research money is a small pot compared to the millions of dollars that Interior Department agencies and the U.S. Forest Service will invest in re-seeding and rehabilitation efforts that could be dashed when lightning strikes those areas the next time.

"The implication for the government is fire, which has never been an issue in the Mojave, is going to be a perpetual issue," Hiatt said.

While he spoke, members of a national, interagency, Burned Area Emergency Response Team huddled in Mesquite, 75 miles northeast of Las Vegas and south of Lincoln County where this year's three largest wildfires burned in Nevada.

Led by Erv Gasser, a natural resource specialist with the National Park Service in Seattle, the team is expected to deliver a stabilization plan this week to Bureau of Land Management officials who will review it and decide on funding.

Among issues such as flash flooding and endangered species concerns, the team is considering options for tackling the non-native plant problem.

"We've got a couple things going on," Gasser said. "Basically we'll have a seeding treatment and emergency stabilization treatments to stabilize and try to mitigate weed invasion."

A second tactic will be to apply a herbicide treatment "that will kill the weeds that pop up and will give (native plant) seeding a better chance," he said.

"We'll also be doing some monitoring of weeds. If there's a problem we'll go in and do another control action," Gasser said, explaining that the "control action" could be to physically or mechanically remove weeds.

Not all of the 800,000 to 900,000 acres of burned areas will be re-seeded. "We've got a lot of rocky areas," he said.

Nevertheless, the weed problem is a major concern and the cost of re-seeding native plants and suppressing weeds "will probably be in the multiple millions" of dollars, he said.

Some restoration efforts already have begun, including rehabilitation of tracks left by bulldozers to fight the fires.

On the research front, Matt Brooks, a botanist with the U.S. Geological Survey in Henderson, has collaborated with scientists from North America, Australia and South Africa to explore the invasive plant problem affecting the Mojave Desert and similar ecosystems.

His work on the role of fire in the control and spread of invasive weeds is cited on the multiagency Joint Fire Science Program Web site.

Congress in 2001 directed the program to expand its research efforts on post-fire rehabilitation and fuels management. One scientist, Kathy Voth, explored the possibility of using goats as a tool to prevent or reduce wildland fire dangers in shrub areas close to urban areas.

Last year, Brooks and colleagues published an article in the journal BioScience titled "Effects of Invasive Alien Plants on Fire Regimes." Among their findings was that restoration of burn areas to their natural state might require costly, drastic measures if the natural surroundings have been altered.

He said much of his work is focused on determining how native plant communities can recover from fires.

"We're evaluating pre-fire fuel management options and post-fire restoration options," he said.

"The invasive problem is pretty significant in the desert in lower elevations where non-native annual grasses allow fires to happen where they didn't before," he said.

That becomes a concern because habitat of wildlife and protected species like the threatened desert tortoise are impacted.