Keeping Options Alive: The Scientific Basis for Conserving Biodiversity.

The diversity of life is an irreplaceable asset to humanity and to the biosphere. It provides both immediate and long-term benefits, and its maintenance is essential to sustainable development worldwide. Components of life that vanish in the next decades will be gone forever; those that remain will provide future options for humanity. This document poses fundamental questions and recommends scientifically informed policies for conserving biological diversity. These policies are derived from current knowledge of biogeography, genetics, conservation biology, and systematics and from population, community, and landscape ecology. Discussed are: (1) the importance of biological diversity; (2) biogeography; (3) species extinction; (4) genetic diversity in agriculture; and (5) recommendations for conservation practices in a global approach. Appendices include "Cascade Effects,""Calculating Extinctions Due to Deforestation,""Protected Area Objectives," and "Glossary." Over 350 references are included. (CW)