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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #254643
Title: Field growth comparisons of invasive alien annual and native perennial grasses in monocultures

Author
item MANGLA, SEEMA - Oregon State University
item Sheley, Roger
item James, Jeremy

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2010
Publication Date: 2/1/2011
Citation: Mangla, S., Sheley, R.L., James, J.J. 2011. Field growth comparisons of invasive alien annual and native perennial grasses in monocultures. Journal of Arid Environments. 75:206-210.

Interpretive Summary: Medusahead is rapidly invading native grassland and cheatgrass dominated grassland throughout the western US. Understanding the relative growth rates and patterns of growth among these species is central to predicting and managing medusahead invasion. We found that bluebunch wheatgrass had more biomass and higher relative growth rate than medusahead in the dry year, but the relationship was reversed in the wet year. Medusahead had a longer period of growth and more total biomass than cheatgrass for both years. We expect medusahead will continue to invade both grassland ecosystems because of its higher relative growth rate and extended period of growth during most years.

Technical Abstract: Medusahead is rapidly invading native grassland and cheatgrass dominated grassland throughout the western US. Understanding growth dynamics of medusahead relative to bluebunch wheatgrass and cheatgrass is central to predicting and managing medusahead invasion. We hypothesized that medusahead would have a higher relative growth rate (RGR), a longer period of growth, and as a consequence, more total biomass at the end of the growing season than bluebunch wheatgrass or cheatgrass. In 2008 (dry conditions), 250 and 2009 (wet conditions), 250 or 100 seeds of each species were sown in 1 meter squared plots with 5 replicates. Shoots were harvested on 3-25 day intervals throughout the growing season and subjected to functional growth analysis. Bluebunch wheatgrass had more biomass and higher RGR than medusahead in the dry year, but the relationship was reversed in the wet year. Historical weather data indicated that the level of drought in 2008 is very rare. Medusahead had a longer period of growth and more total biomass than cheatgrass for both years. We expect that medusahead will continue to invade both grassland ecosystems because of its higher RGR and extended period of growth.