ARS | Publication request: Plant material testing and cheatgrass suppression: a 10 year old case study

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 9, 2011
Publication Date: February 1, 2012
Citation: Clements, D.D., Young, J.A., Harmon, D.N. 2012. Plant material testing and cheatgrass suppression: a 10 year old case study. In: Proceedings of Society for Range Management, January 29-February 3, 2012, Spokane, Washington. 65:45.

Technical Abstract: Cheatgrass (Bromus tectorum) is an exotic and invasive annual grass that was accidentally introduced to western North America in the late 19th century. Cheatgrass soon spread across millions of hectares of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis)/ bunchgrass rangelands throughout the Intermountain Area. Cheatgrass provides an early maturing, fine textured fuel that increases the chance, rate, spread and season of wildfires. With each passing wildfire season, more and more critical habitats are burned up and converted to cheatgrass dominance. In 2000, following an herbicidal application and fallow of a cheatgrass dominated site in northern Nevada, we seeded 16 separate species (8 grasses, 4 shrubs and 4 forbs) in an effort to test the ability of these 16 plant species to germinate, sprout, establish and suppress cheatgrass. The ultimate goal of this project was to identify those plant species, adapted to this site, that ultimately have the inherent potential to establish in the face of cheatgrass competition and to suppress cheatgrass to a point where the absence of wildfire would allow critical shrub communities to return. This research was conducted at Antelope Creek, near Orovada, Nevada at an elevation of 15,180 m. The site had repeatedly burned since the big firestorm of 1939. The soils are a silty loam in a 20-25 cm precipitation zone. In the fall of 1999, Sulfometuron Methyl, trade name ‘Oust’, was applied at .10 g/ha rate to the study site and fallowed for one year. In the fall of 2000 we seeded native and introduced plant materials with both a no-till drill and rangeland drill application at various seeding rates. In May of 2001 we started recording seedling densities, which were monitored for the next 10 years. Each plot consisted of five 1 m² quadrats which were randomly located, which became fixed quadrats over-time to measure seedling mortality and densities. Prior to the herbicide application cheatgrass densities averaged 4,900/m². Cheatgrass densities following herbicidal control in the summer prior to the fall seeding averaged 9.24/m². In May 2001 ‘Hycrest’ crested wheatgrass and ‘Sherman’ big bluegrass (Poa secunda formerly P. ampla) had the highest seedling density at 16.5/m² and 8.6/m², respectfully. Bluebunch wheatgrass (Pseudoroegneria spicata ssp. spicata) also showed fairly good seedling densities at 4.6/m². The site received 19.41 cm of precipitation (recorded from October 1st-September 30th) in 2000/2001 and 21.66 cm in 2001/2002. By June 2010, ‘Hycrest’ crested wheatgrass and ‘Sherman’ big bluegrass were the two plant species that performed the best stood out as good revegetation candidates at this site with densities at 4.6/m² and 3.6/m². Cheatgrass densities in June 2010 in the ‘Hycrest’ and ‘Sherman’ plots averaged 7.3/m² and 10.2/m² compared to 817.4/m² in the control, 204/m² in the bluebunch wheatgrass and 301.62/m² in the squirreltail (Elymus elymoides) plots. Better understanding the inherent potential of seed species to germinate, sprout, and establish in the face of such fierce competitors as cheatgrass is critical if land managers are going to be successful in reversing the tide of cheatgrass dominance, frequent wildfires, and loss of critical wildlife habitats and grazing resources.