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item Ziska, Lewis

Submitted to: World Resource Review
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2004
Publication Date: 11/1/2004
Citation: Ziska, L.H., George, K. 2004. Rising carbon dioxide and invasive, noxious plants: Potential threats and consequences. World Resource Review. 16:427-447.

Interpretive Summary: Plants use carbon dioxide as "fuel" for growth. Right now, in the atmosphere, there is not enough carbon dioxide to optimize plant growth. So as humans release more carbon dioxide into the atmosphere, plants will grow more. While some plants are beneficial to society, other plants are considered harmful. One group of harmful plants are "invasive" plants. These are foreign, alien plant invaders that come into the U.S. accidently and cause economic damage. We reviewed our own and other scientists' experiments to figure out whether rising carbon dioxide affects the growth of these invasive plants. We discovered that invasive plants did, in fact, show a much stronger than expected response to rising carbon dioxide. We also found that in groups of plants (communities), carbon dioxide appears to stimulate the growth of these invasive plants more than others. In addition, there is some initial scientific data to suggest that chemicals that control invasive plant growth (herbicides) may be less effective as carbon dioxide increases in the atmosphere. However, there are only a few published data that have addressed carbon dioxide and invasive weeds, and for the moment any general conclusions remain uncertain. Still, given the economic and environmental damage caused by these invasive plants (estimated in the billions of dollars), it would be useful to have additional experiments to address these uncertainties. This information is necessary for government agencies, stakeholders and land managers in order to assess the extent of the invasive weed problem and to develop appropriate management solutions.

Technical Abstract: Because current levels of atmospheric CO2 are less than optimal for plant growth, recent and projected increases in this gas are expected to stimulate the growth of a number of plant species. However, the rise in carbon dioxide is indiscriminate in stimulating the growth of both wanted and unwanted plants. One group of unwanted plants which is receiving increased recognition are invasive, noxious weeds. To determine whether rising carbon dioxide has been a factor in the establishment and success of such weeds, we have compared the potential response to recent and projected changes in carbon dioxide between invasive, noxious species and other plant groups, and assessed whether carbon dioxide preferentially selects for such species within ecosystems. A synthesis of literature results indicates that invasive, noxious weeds have a larger than expected growth increase to both recent and projected increases in atmospheric carbon dioxide. There is also evidence from a limited number of experiments that rising carbon dioxide can preferentially select for invasive, noxious species within plant communities. In addition, there is initial data suggesting that chemical control of such invasives may be more difficult in the future. However, the small number of available studies make such conclusions problematic, and emphasize the urgent need for additional investigations to address the biological and economic uncertainties associated with carbon dioxide-induced changes in the ecology of invasive, noxious weeds.