Increased levels of ozone associated with the release of greenhouse gases are causing vegetation to use more water and may intensify the effects of global warming on ecological systems, according to findings published in New Phytologist. Researchers Sandy McLaughlin of the University of Tennessee and Stan Wullschleger of Oak Ridge National Laboratory conducted studies of trees in the mountains of East Tennessee and found that current levels of ozone amplified the effects of climate stresses on large tree growth, transfer of water from soil to the atmosphere and rates of stream flow from forested watersheds. The mechanism for these effects, which has been implicated by several studies, is reduced capacity of the plants to regulate water loss through stomata, the breathing pores in leaves. Researchers cautioned, however, that they need to test these concepts further with additional forest types and climatic systems. Others involved in this study, funded by a grant from the U.S. Department of Agriculture Forest Service, Southern Global Change Program, were from the Forest Service and the University of Calgary.
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