Medusa head taking over rangelands, threatening grazing

New research suggests that an invasive plant called Medusa head will keep taking over rangelands in the West, vastly reducing the grazing potential for livestock as well as wildlife. The study published in the latest issue of the Journal of Arid Environments confirmed the hypothesis that one reason Medusa head is taking over is because most years it grows faster and for a longer period than native grasses and even other invasive plants, such as cheatgrass. Seema Mangla, a research scholar at Oregon State University who was lead author on the study, said Medusa head already infests 2 million acres, mostly in the West, and is spreading at a rate of 12 percent a year. Once it invades an area, the grazing potential goes down by 80 percent. "This species has a high growth rate and can stay for a longer period in the soil," she said. "This is the main cause of the problem." The study looked at the growth of Medusa head in a sagebrush ecosystem in southeastern Oregon in 2008, a dry year, and 2009, a wet year. It found that Medusa head lagged behind the native bluebunch wheatgrass in the dry year, but was far ahead of it in the wet year. The study noted the dry year was far below normal and not repeated often. In both years, Medusa head grew faster and for a longer time than cheatgrass. Livestock, deer and elk won't eat it because the seeds have spines, known as awns, that hurt animals' mouths, and the plant is high in the mineral silica...more