How Ecosystems Respond to Stress

Abstract

U.S. Environmental Protection Agency. #The effects of stress were examined in the Laurentian Great Lakes Basin, North America, North American desert grasslands and in the Kyronjoki river and estuary, Finland. The common stress pressures that these ecosystems are exposed to include physical restructuring (land use change), over harvesting, pollution by wastes and the introduction of exotic species. The specific effects of these stresses on the ecosystems are described and the main trends in the etiology of ecosystem breakdown are given. Difficulties encountered when trying to rehabilitate damaged ecosystems are discussed; contrary to popular belief, highly degraded ecosystems did not 'bounce back' once stress loads were lessened, or even when enormous efforts were put in to artificially recreate the habitat. Data providing evidence for ecosystem distress syndrome are tabulated for the ecosystems. It is concluded that the most effective way to ensure healthy ecosystems is to undertake preventive measures to limit stress pressures so that self-reinforcing degradative processes are not set in motion.