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Report: Invading, alien weeds could be No. 1 threat to U.S. rangeland

Published: Wednesday, March 27 2013 6:07 p.m. MDT

SALT LAKE CITY — Their names are as obnoxious and noxious as their behavior: Medusa Head. Camel Thorn. Leafy Spurge and Dyer's Woad.

They are among 3,100 invader plant species in the United States that laid siege to range land in the past two decades, spreading at alarming rates — some marching across as much as 4,000 acres a day — and there is no sign of them slowing the takeover, according to a new U.S. Forest Service Report.

"The expansion of invasive species, particularly the exotics, could pose the largest threat to the future health of U.S. range lands and cause a serious financial burden to society," said the technical analysis released Wednesday by the Rocky Mountain Research Station in Fort Collins, Colo.

Damage and control costs across the country eclipse $137 billion annually, playing out in ruinous ways such as range land rendered useless for grazing, spoiled crops and water quality impairment. Non-native weeds are also blamed in part for the rampant acceleration of catastrophic wildfires because many of the most pervasive species can actually take root in charred soils. Some significantly alter fire frequency and intensity.

The report estimates that non-native weeds are suspected to be present on nearly half of U.S. range lands and represent more than 50 percent of the total plant cover.

In Utah, for example, stubborn phragmites have invaded the shoreline of Utah Lake, choking out native vegetation that helps waterfowl thrive.

Cheat grass dominates on much of the range land throughout the state, out-competing the other grasses and providing poor nutrition for livestock and wildlife.

Farmers, ranchers, state agencies and county governments all wage a war each year to try to stamp out the weeds, but their persistence is daunting.

"It is a problem that touches all of us," said Larry Lewis, spokesman for the Utah Department of Agriculture.

The department is dealing with relatively new threats that have emerged from the dirt in places like San Juan County and southern Utah: camel thorn and Medusa head.

Some noxious weeds like the leafy spurge sound like they are straight out of a science-fiction themed horror movie — possessing deep root systems that suck away precious water in an arid state like Utah — and having a head of flowering shoots that can each spread 140 seeds up to 15 feet away. The creeping, perennial weed if left unchecked can reduce the range land's cattle carrying capacity by as much as 75 percent.

Robert Hougaard, director of the department's plant industry section, said it is a constant battle to keep the plants at bay.

The agency awarded $1 million in grants this fiscal year and is readying to appropriate $1 million more in this coming fight, with 56 applications that are undergoing the review process.

Despite the array of economic and ecological ramifications inherent with invasive weeds, the report noted a startling lack of interagency coordination at a national level to combat the issue. 

Although dozens, maybe even hundreds of programs exist that specialize in different aspects of noxious weeds, groups tasked with research and management of the problem do not have a centralized, public database that describes the extent of the problem.

"The lack of cohesiveness makes developing a report on the status and trends of invasive species on U.S. range lands problematic," the Forest Service report noted.

Spurred by a Inspector General's audit in 2010, however, the U.S. Forest Service worked with six other agencies that include the Department of Interior, the EPA and even the Department of Defense in efforts that resulted in the establishment of a federal committee to increase the availability of information.

E-mail: amyjoi@deseretnews.com

Twitter: amyjoi16

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