Invasive annual grasses are a growing threat to the Great Basin desert ecosystem which includes much of Eastern Oregon. These grasses — such as medusahead, cheatgrass and ventenata — displace native plants, reduce habitat diversity for important wildlife like the greater sage-grouse, shorten the grazing season for livestock and increase the risk of wildfire. They also contribute to significant economic losses for landowners and ranchers by reducing the grazing capacity of rangelands.
Thanks to this work, communities in Eastern Oregon are better equipped to protect their rangelands from invasive grasses, reduce wildfire risk and restore the productivity and resilience of these vital ecosystems.
These exotic grasses spread rapidly across sagebrush rangelands by filling in the spaces that native perennial bunchgrasses usually occupy. Unlike native plants, they create a dense carpet of fine fuel that makes wildfires more frequent and severe.
This fire cycle further damages the ecosystem, encourages more invasive growth and degrades the habitat that species like sage-grouse depend on. Sage-grouse populations have been steadily declining in North America, with the fewest male birds recorded in 2019 after more than a century of population tracking.
Restoring land already invaded by these grasses is both difficult and costly — seeding desirable vegetation often fails to take hold. That’s why prevention and strategic management are critical.
In response to this urgent challenge, Oregon State University Extension Service researchers at the Eastern Oregon Agricultural Research Center in Burns have worked with local, state and federal agency partners to combat invasive annual grasses. They have contributed to multiple initiatives including applied studies, grazing trials and land management tools designed to build ecosystem resilience and improve rangeland restoration success.
One of the key contributions is the Medusahead Management Guide, which outlines practical strategies for limiting the spread of invasive grasses and restoring the ecological functions of sagebrush steppe. The guide is now being used by the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) to support medusahead control and revegetation programs in southeast Oregon.
They collaborated with the High Desert Partnership and the Oregon SageCon Partnership to produce the Invasive Annual Grass Workshop, a two-day virtual event featuring 32 speakers. The workshop's success led to a special issue of the peer-reviewed journal Rangelands. This issue serves as an urgent call to action for coordinated efforts in managing invasive grasses and wildfire risks.
OSU research has also shown that maintaining healthy perennial vegetation is key to resisting reinvasion and that certain dormant season grazing practices can help reduce medusahead while promoting the recovery of desirable native plants. Understanding landowner perspectives has also been a focus, helping identify barriers to implementing effective invasive species control.
These efforts have already led to meaningful on-the-ground results. Findings from their research helped secure a $152,000 Oregon Watershed Enhancement Board grant to restore 20,000 acres of medusahead-invaded rangeland in western Harney County.
The Baker County Soil and Water Conservation District used the guidelines in a major sage-grouse habitat restoration project. And multiple agencies across southeastern Oregon including the NRCS are putting these strategies into action.
Thanks to this work, communities in Eastern Oregon are better equipped to protect their rangelands from invasive grasses, reduce wildfire risk and restore the productivity and resilience of these vital ecosystems.