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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #322738
Title: Cheatgrass is favored by warming but not CO2 enrichment in a semi-arid grassland

Author
item Blumenthal, Dana
item Kray, Julie
item ORTMANS, W - University Of Liege
item Ziska, Lewis
item PENDALL, E - Western Sydney University

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2016
Publication Date: 4/30/2016
Citation: Blumenthal, D.M., Kray, J.A., Ortmans, W., Ziska, L.H., Pendall, E.P. 2016. Cheatgrass is favored by warming but not CO2 enrichment in a semi-arid grassland. Global Change Biology. 22:3026-3038. doi:10.111/gcb.13278.

Interpretive Summary: Increases in atmospheric carbon dioxide and consequent changes in climate are expected to dramatically alter the species composition and distribution of plant communities, and therefore a wide range of ecosystem services. Cheatgrass (Bromus tectorum) increases fire frequency and reduces biological diversity across millions of hectares in western North America. Here we show that experimental warming promotes cheatgrass invasion of northern mixed-grass prairie. This result was observed with and without competition from native species, under wet and dry conditions, and despite the fact that warming reduced soil water. In contrast, carbon dioxide enrichment had little effect on cheatgrass invasion or soil water, while reducing soil and plant nitrogen. We conclude that warming may allow cheatgrass to more successfully colonize the extensive, invasion-resistant northern mixed-grass prairie. Furthermore, effects of elevated CO2 on B. tectorum, and possibly other invasive species, may be mediated by nitrogen availability.

Technical Abstract: Global change impacts may be compounded by invasive species with strong community and ecosystem impacts. Bromus tectorum (cheatgrass) increases fire frequency and reduces biological diversity across millions of hectares in western North America. Here we show that B. tectorum recruitment, growth and seed production increase under infrared warming (+1.5 oC day/3 oC night) in northern mixed-grass prairie. These results were observed with and without competition from native species, under wet and dry conditions, and despite the fact that warming reduced soil water. In contrast, free air CO2 enrichment (600 ppmv) had little effect on B. tectorum invasion or soil water, while reducing soil and plant nitrogen (N). We conclude that warming may expand B. tectorum’s phenological niche, allowing it to more successfully colonize the extensive, invasion-resistant northern mixed-grass prairie. Furthermore, effects of elevated CO2 on B. tectorum, and possibly other nitrophilic invasive species, may be mediated by N availability.