While dirty air spreads across large areas of the New England region, it's more scattered in the southeastern part of the United States. Details were presented during a symposium on indicators of forest health on Tuesday, Aug. 3, at the annual meeting of the Ecological Society of America in Portland, Ore.

As part of national project to monitor the health of forests, including the trees and everything else living in these ecosystems, researchers from the University of Wisconsin-Madison and the U.S. Forest Service have turned to the leafy or tufted species of lichens.

Lichens typically live on tree trunks, branches and rocks on the forest floor, and they're well known for their sensitivity to environmental change, such as air pollution, says Susan Will-Wolf, a UW-Madison associate scientist in botany, who is involved in the project. "They're the 'canary in the mine' that can provide an advance warning of potential hazards."

Changes in lichen communities, she adds, are an indicator of the possibility for changes within the ecosystem, such as less-efficient nutrient cycling or slower forest growth. "While forests are important for timber production, they are also important for maintaining watersheds and protecting biodiversity," says Will-Wolf. "This ability may be impaired under certain conditions."

Recognizing the potential of these plants to signal changes in the environment, the Wisconsin botanist and her colleagues developed regional models based on lichen community composition to assign air-quality scores to forest plots and predict the impact of air pollution on forests. The models show, for example, that areas with dirtier air tend to have fewer species of lichens. The opposite is true for areas with cleaner air.

With these models, Will-Wolf and others used data collected by the U.S. Forest Service to monitor lichen communiti
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Contact: Susan Will-Wolf
swwolf@wisc.edu
608-262-2754
University of Wisconsin-Madison
1-Aug-2004