The word ecology was coined in 1870 by the German zoologist Ernst Haeckel from the Greek words oikos (house) and logos (logic or knowledge) to describe the scientific study of the relationships among organisms and their environment. Biologists began referring to themselves as ecologists at the end of the nineteenth century and shortly thereafter the first ecological societies and journals appeared. Since that time ecology has become a major branch of biological science. The contextual, historical understanding of organisms as well as the systems basis of ecology set it apart from the reductionist, experimental approach prevalent in many other areas of science.

This broad ecological view is gaining significance today as modern resource-intensive lifestyles consume much of nature's supplies. Although intuitive ecology has always been a part of some cultures, current environmental crises make a systematic, scientific understanding of ecological principles especially important.

For many ecologists the basic structural...