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Title: Competition effects from cheatgrass (Bromus tectorum) differs among perennial grasses of the Great Basin

item Harmon, Daniel - Dan
item Clements, Darin - Charlie

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/12/2016
Publication Date: 1/29/2017
Citation: Clements, D.D., Harmon, D.N. 2017. Competition effects from cheatgrass (Bromus tectorum) differs among perennial grasses of the Great Basin. Society for Range Management Meeting Abstracts. 70:46.

Interpretive Summary:

Technical Abstract: Competition from the exotic annual grass, cheatgrass (Bromus tectorum), threatens millions of hectares of native plant communities throughout the Great Basin. The Nature Conservancy has identified the Great Basin as the third most endangered ecosystem in the United States. Not only has increased fuels and fire frequency from cheatgrass invasion altered ecosystem biodiversity, the highly competitive nature of cheatgrass can also make management, restoration, and preservation attempts largely ineffective. The perennial grass component of the plant community is key to resisting cheatgrass dominance. Seeding efforts and natural recruitment of native perennial grasses has been historically less successful than non-native rehabilitation grasses. To understand the discrepancy of success, we observed first-year growth (biomass) and survival of three native and one non-native rehabilitation perennial grasses in large outdoor non-irrigated soil containers using soils collected from three northwestern Great Basin USDA-ARS field sites. With cheatgrass as the single treatment factor, perennial seedlings were grown individually or with cheatgrass (6 plants) for one growing season. Growth of the non-native crested wheatgrass (Agropyron cristatum) decreased the least when competing with cheatgrass (30% decrease), while the native Sandberg blue grass (Poa secunda) had the largest decrease in growth (94%). Squirreltail (Elymus elymoides) and crested wheatgrass had a 25% decrease in survival from cheatgrass competition while Sandberg bluegrass had the largest decrease in survival (60%). Bluebunch wheatgrass (Pseudorogneria spicata) survival was not effected by cheatgrass competition, however, it had little survival without any cheatgrass competition. Under non-competitive conditions, crested wheatgrass has been observed to have higher growth rates compared to the three native grasses and our results found that disparity was greatly magnified by cheatgrass competition. This study’s results emphasize the importance of active weed control practices (e.g., soil actice herbicides) on species such as cheatgrass, to decrease competition prior to seeding efforts, especially if a native-only policy is implemented.