Local impacts of a rural coal-burning generating station on lichen abundance in a New England forest

To test whether emissions from a coal-burning, electrical generating station in rural Massachusetts have had measurable ecological impacts on the surrounding riparian forest, we compared abundance of epiphytic lichens at different distances from the station. Per cent covers of crustose, fruticose, and foliose lichens were measured along 1-km transects downwind and upwind from the station on the north and south sides of trunks of two dominant tree species, Acer saccharinum and Populus deltoides. Lichen cover increased with distance from the station, especially in the upwind direction. The tendency for lichens to be more abundant on the north than on the south side of trees also increased with distance from the station. These effects of distance and side on lichen abundance were stronger in some lichen growth forms than in others and also depended on host tree species. Two different methods of measuring lichen cover, visual estimate and point occurrence, gave similar values. We conclude that emissions from the station have had measurable impacts on the adjoining plant community