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Title: Effects of Elevated Atmospheric CO2 on Invasive Weed Species in Managed Terrestrial Ecosystems of the Southeastern U.S.

Author
item Rogers Jr, Hugo
item GJERSTAD, DEAN - AUBURN UNIVERSITY
item Runion, George
item Prior, Stephen - Steve
item Price, Andrew
item VAN SANTEN, EDGAR - AUBURN UNIVERSITY
item Torbert, Henry - Allen

Submitted to: Technical Report
Publication Type: Other
Publication Acceptance Date: 2/6/2006
Publication Date: 2/16/2006
Citation: Rogers Jr, H.H., Gjerstad, D.H., Runion, G.B., Prior, S.A., Price, A.J., Van Santen, E., Torbert III, H.A. 2006. Effects of elevated atmospheric CO2 on invasive weed species in managed terrestrial ecosystems of the Southeastern U.S. Final Technical Report. Southeastern Regional Center, National Institute for Global Environmental Change, University of Alabama, Tuscaloosa, Alabama. p. 4.

Interpretive Summary: A neglected aspect of global environmental change is how invasive plants might react to the rise in atmospheric CO2 level. Invasive plants can disrupt farm and forest systems and this threat is great for the southeastern U.S., with its numerous ports of entry and mild climate. We studied the response of several invasive plants by growing them under two levels of atmospheric CO2 (ambient or elevated). While most plants grew larger under high CO2, grasses showed a smaller growth response to CO2. We also found a delay or reduction in flowering under high CO2. Our findings suggest that although these invasive plants may grow bigger in a high CO2 world, their ability to spread might be reduced.

Technical Abstract: Invasive plants are estimated to cost U.S. agricultural and forest producers 34 billion dollars each year from lost productivity and increased costs for weed control. While much effort is being spent studying these exotic plant pests, little work has been done into how invasive plants might react to the increasing carbon dioxide (CO2) concentration in the atmosphere. We grew a variety of invasive plants under ambient and elevated levels of CO2 from the seedling stage through flowering at which time they were harvested and measured. Virtually all the plants studied grew larger (9-40%) when exposed to elevated CO2; however, the response to additional CO2 varied greatly among species. In general, plants responded as expected according to their type, with grasses having less response than other species. This suggests that, while both types of weeds are likely to become worse pests as atmospheric CO2 increases, grass weeds may not be as big a problem as other weeds. Also, several weeds showed a delay or decrease in flowering when exposed to elevated CO2 which suggests that, while invasive weeds may grow larger under a future, high CO2 environment, their ability to spread might be reduced; this possibility certainly deserves further research.