The Earth's biotic resources are experiencing a spreading crisis, which is leading not only to the most rapid loss of species in the past 65 million years, but also causing abrupt changes in the structure and function of natural communities. This disturbance, unfortunately, is the result of man's carelessness in the name of advancing civilization. To identify and begin rectifying this dangerous situation, a group of outstanding environmental scientists has compiled a collection of case studies that illustrate the changes being wrought on the biosphere by the human presence. The first part of...