Researchers: Global warming could increase West's wildfire risk

RENO - Global warming could accelerate the spread of exotic plant species, crowding out native varieties and increasing the risk of devastating wildfires in Nevada and other arid regions of the West, a team of Nevada researchers says.

The six reseachers from Nevada's higher education system released the findings of a three-year study in an article in the science journal Nature.

''Looking ahead it's just scary,'' said James Coleman, vice president of research and business development at the Reno-based Desert Research Institute. ''We're talking about a massive change of that whole ecosystem.''

At a facility near the Nevada Test Site in Southern Nevada, the team studied how desert vegetation would react to elevated levels of carbon dioxide expected in the atmosphere in 2050.

Scientists sprayed high concentrations of carbon dioxide - about 50 percent higher than what's now found in the air - across plots of desert plants.

The elevated levels of carbon dioxide accelerated growth of both native and non-native species as expected, but the growth of exotic grasses was particularly surprising, researchers said.

The non-native annual grass red brome experienced a more than twofold increase in production, far outpacing native desert plants.

The finding suggests that as emissions pour more carbon dioxide into the atmosphere in coming decades, red brome will spread readily across Southern Nevada while non-native cheatgrass will do the same in Northern Nevada, researchers said.

Impacts would range from the loss of native plants and the wildlife that depend on them to increasing wildfire danger.

Cheatgrass and red brome received much of the blame for Nevada's record 1999 fire season when 1.6 million acres were blackened. Wildland fires burned 650,000 acres in Nevada this season.

''Red brome, and likely cheatgrass as well, will continue to grow even more dominant relative to native annual species ... as atmospheric CO2 concentration increases,'' said Jeff Seemann, chairman of the University of Nevada, Reno's biochemistry department.

''With this effect of rising CO2, the potential of these invasive grasses to exacerbate the fire cycle is even worse.''

Although the region's average fire cycle lasts 75 years or more, the dominance of cheatgrass could reduce the cycle to as little as four to seven years, the researchers found.

''In a lot of ways, the experiment we are doing is a look into the future, and the future doesn't look so good,'' said Bob Nowak, a professor of environmental and resource sciences at UNR.

The Bureau of Land Management has announced a long-term plan to battle the invasion of cheatgrass, which already has spread across 25 million acres of high desert in Nevada, Utah and Oregon.

''We really better get after this and really get it done,'' Nowak said. ''Then we'll at least have a chance to at least keep a lid on it.''