Long-term exposure to elevated CO2 enhances plant community stability by suppressing dominate plant species in a mixed grass prairie

Authors: ZELIKOVA, T - University Of Wyoming; Blumenthal, Dana; WILLIAMS, D - University Of Wyoming; SOUZA, L - University Of Oklahoma; Lecain, Daniel; MORGAN, J - Retired ARS Employee; PENDALL, E - Western Sydney University

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2014
Publication Date: 9/16/2014
Publication URL: http://handle.nal.usda.gov/10113/60366
Citation: Zelikova, T.J., Blumenthal, D.M., Williams, D.G., Souza, L., Lecain, D.R., Morgan, J.A., Pendall, E. 2014. Long-term exposure to elevated CO2 enhances plant community stability by suppressing dominate plant species in a mixed grass prairie. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1414659111.

Interpretive Summary: Some vegetation types are more vulnerable to climate change, while others are more resistant. In a mixed grass prairie in the northern Great Plains, we used a large field experiment to test the effects of elevated carbon dioxide (CO2), warming, and summer irrigation on plant community structure and productivity, linking changes in both to overall community stability. We show that this mixed-grass prairie ecosystem is not only relatively resistant to interannual variation in precipitation, but also rendered more stable by elevated CO2. This increase in stability is the result of a decrease in the relative abundance of dominant species and a resultant increase in the relative abundance of subdominant species. In many grasslands that serve as rangelands, the economic value of the ecosystem is largely dependent on the plant community and the relative abundance of key forage grass species. Thus, our results have implications for how we manage native grasslands in the face of changing climate.

Technical Abstract: Climate drives the distribution of vegetation across the globe and some vegetation types are more vulnerable to climate change, while others are more resistant. Because inherent resistance and resilience and their relationship with ecosystem stability can play important roles in how communities and ecosystems respond to climate change, we need to evaluate the potential for resistance as we predict future ecosystem function. In a mixed grass prairie in the northern Great Plains, we used a large field experiment to test the effects of elevated CO2, warming, and summer irrigation on plant community structure and productivity, linking changes in both to overall community stability. We show that the independent effects of CO2 and warming on plant community composition and productivity depend on inter-annual variation in precipitation and that the effects of elevated CO2 are not limited to water saving as they differ from those of irrigation. We also show that this mixed-grass prairie ecosystem is not only relatively resistant to interannual variation in precipitation, but also rendered more stable under elevated CO2 conditions. This increase in stability is the result of altered community dominance patterns, a decrease in the relative abundance of dominant species and resultant increase in the relative abundance of subdominant species. In many grasslands that serve as rangelands, the economic value of the ecosystem is largely dependent on the plant community and the relative abundance of key forage grass species. Thus, our results have implications for how we manage native grasslands in the face of changing climate.