American grasslands being taken over by destructive weed species

Sunday, November 21, 2010 by: Jonathan Benson, staff writer
Tags: grasslands, weeds, health news

(NaturalNews) A highly invasive weed known as medusahead is taking over American grass and range lands and rendering them worthless, according to a new study out of Oregon State University (OSU). The Mediterranean-based plant has been in the U.S. since the 1800s, but its growth and spread has become so out of control that the integrity and viability of soil, pasture, and crops is at significant risk.

"Medusahead is now spreading at about 12 percent a year over 17 western states," explained Seema Mangla, a researcher at the OSU College of Forestry. "Once established, it's very hard to get rid of. It displaces native grasses and even other invasive species that animals can still eat. Unless we do more to stop it, medusahead will take over much of the native grassland in the West."

The main problems associated with medusahead include its tendency to prevent other plants from germinating, particularly those that animals and livestock need for food. The plant itself is inedible and contains a high silicon content, and it is actually harmful to animals. It also hogs soil nutrients and water, which together with its other negative effects, is a recipe for ecological disaster.

"Annual grass invasion is driving one of the largest changes in vegetation structure ever documented," wrote the researchers in their study. "This conversion has major negative impacts on ecosystem function, wildlife and fire regimes."

Experts say that keeping medusahead out of land is much easier than trying to fight it once it has taken hold. So they are investigating the best ways to keep it from overtaking native grasses and other competing invasive species, all while avoiding conventional deterrent methods.

"For too long we've treated these invasive species as something you just mow, spray with herbicides, or chop out somehow, and then forget about them," said Mangla. "That just treats the symptoms but doesn't get to the underlying problem. If we're going to stop something like medusahead, we have to better understand its ecology and find ways to compete with it."

Sources for this story include:

http://oregonstate.edu/ua/ncs/archives/2010/...