Restoring Annual Grass Invaded Landscapes

The Sagebrush Steppe Ecosystem in central Oregon with cheatgrass and other annual invasive grasses i

Corinna Holfus | Graduate Research Assistant | Department of Animal and Rangeland Sciences | Rangeland Ecology and Management

Stepp(e)ing Up

Much of the western United States and, more specifically, the sagebrush steppe ecosystem has been invaded with annual grasses. These grasses negatively affect the ecosystem by increasing the fire frequency and intensity, changing the fundamental nutrient cycling processes within the soil, and out-competing native vegetation. The annual invasive grass cheatgrass (Bromus tectorum) is the most widely spread and problematic weed in the intermountain west region of North America.

Graduate student Corinna Holfus, monitoring the success of a first-year field study.
A seed coated with the activated carbon mixture has emerged showing potential success of seed coating!

Investigating the Invaders

My research specifically focuses on restoration solutions to eradicate this invasive grass and revegetate the area with native perennial bunchgrasses and sagebrush. One aspect of this research is to restore perennial bunchgrasses through the development of a grass seed coating. Native grass seed is coated in a mixture containing activated carbon that will protect the seed from herbicide. The coated native seed can be seeded over the cheatgrass and simultaneously sprayed with herbicide. The coating protects the native seed from herbicide and the herbicide kills the surrounding cheatgrass.

Sagebrush (Artemisia tridentata ssp. wyomingensis) can be difficult to restore in recently burned areas or cheatgrass stands especially through the use of traditional broadcast or drill seeding. This is why the use of transplants has been used more frequently and has shown more promise. I am specifically looking at how the timing of planting, age of transplant when planted, and competition with annual grasses affects the survivability of these sagebrush transplants.

Graduate student Corinna Holfus, showing the success of seed coatings in cheatgrass stands. Note the surrounding grass is cheatgrass!
A team at The Nature Conservancy seeding native grass seed in cheatgrass stands at Juniper Hills Preserve in Oregon. From left to right: Jennifer Ruthruff, Corinna Holfus, Jessie Griffen.

Fighting Devastating Wildfires

Cheatgrass and annual invasive grasses in general play a large role in the devastating wildfires we see today. Historically, high desert regions had much more bare ground and biological crusts in the interspaces between shrubs and perennial bunchgrasses. After cheatgrass invades a landscape, these interspaces become carpeted with cheatgrass. When lightning strikes or a fire starts, the cheatgrass provides a more continuous fuel bed for fire creating a much larger and devastating fire. By eradicating this invasive grass and restoring the native vegetation, we are preventing the spread of large devastating wildfires.

United Front

My research partners include USDA Agricultural Research Service and The Nature Conservancy.