Responses of American forests to photochemical oxidants.

Abstract

Photochemical oxidants produced over urban areas in North America contribute to the development of regional levels of air pollution which have been injurious to forests. Ozone data recorded since 1974 suggest that the Pacific Southwest and the Atlantic Northeast have the greatest potential for tree damage. Ozone persists longer in nonurban areas because of the absence of chemical scavengers. Tree and forest decline in response to ozone has been demonstrated in a limited number of studies in North America. Chronic injury to forests has been reported in the transverse mountain ranges of southern California, the Blue Ridge and S Appalachian Mountains, and the Cumberland Plateau of Tennessee. Similar levels of chronic injury are probably occurring in the mountains southwest of Mexico City.-from Authors