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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Pest Management Research » Research » Publications at this Location » Publication #300900

Title: Soil sterilization alters interactions between the native grass Bouteloua gracilis and invasive Bromus tectorum

Author
item EMAM, TARANEH - University Of California
item Espeland, Erin
item Rinella, Matthew - Matt

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2014
Publication Date: 9/16/2014
Publication URL: http://handle.nal.usda.gov/10113/59649
Citation: Emam, T., Espeland, E.K., Rinella, M.J. 2014. Soil sterilization alters interactions between the native grass Bouteloua gracilis and invasive Bromus tectorum. Journal of Arid Environments. 111:91-97. DOI: 10.1016/j.jaridenv.2014.08.006.

Interpretive Summary: Bromus tectorum (cheatgrass, downy brome) is a grassland invasive plant throughout the western US. We asked whether soil biota increase growth and competitive ability of Bromus, and whether responses vary between soils collected at different sites. In a greenhouse study, Bromus and Bouteloua gracilis individuals were grown alone or in competition with one another, with soil biota present or removed via sterilization. Soil inoculum was gathered at 15 sites in the Northern Great Plains. Bouteloua was better able to compete with Bromus when soil biota were absent. This may be because Bromus size was larger when soil biota were present and therefore represented a larger competitive obstacle to Bouteloua in this environment. Bromus response to soil biota varied by site, which may have been due to a combination of environmental factors that shaped the microbial communities at these sites.

Technical Abstract: Aims: The invasive grass Bromus tectorum negatively impacts grassland communities throughout the western U.S. We asked whether soil biota growing in association with a native grass (Bouteloua gracilis) increase growth and competitive ability of Bromus, and whether responses vary between soils collected at different sites. Methods: In a greenhouse study, Bromus and Bouteloua individuals were grown alone or in competition with one other, with soil biota present or removed via sterilization. Soil inoculum was gathered at 15 sites in the Northern Great Plains. Results: Sterilization alone reduced Bromus and Bouteloua biomass by similar amounts (48% and 50% respectively, according to point estimates). When competition and sterilization treatments were applied together, Bromus biomass was lower than predicted based on responses to individual treatments, whereas Bouteloua biomass was higher than predicted. Response to sterilization varied by site for Bromus, but not Bouteloua. Conclusions: Bouteloua was better able to compete with Bromus when soil biota were absent, possibly due to increased Bromus size in response to additional nutrients or other growth stimulation when soil biota were present. Differences in Bromus response to soil biota by site may have been due to a combination of environmental factors that shaped the microbial communities at these sites.