The earth's landscapes are being increasingly impacted by the activities of man. Unfortunately, we do not have a full understanding of the consequences of these disturbances on the earth's productive capacity. This problem was addressed by a group of French and U.S. ecologists who are specialists at levels of integration extending from genetics to the biosphere at a meeting at Stanford, California, sponsored by the National Science Foundation and the Centre National de la Recherche Scientifique. With a few important exceptions it was found at this meeting that most man-induced disturbances of...