Ecosystem consequences of changing biodiversity

F. Stuart Chapin (e-mail: fschapin@socrates. berkeley.edu) is a professor and David U. Hooper is a postdoctoral fellow in the Department of Integrative Biology, University of California, Berkeley, CA 94720. Osvaldo E. Sala is a professor at the Faculty of Agronomy, University of Buenos Aires, Av. San Martin 4453, Buenos Aires 1417, Argentina. Ingrid C. Burke is an associate professor in the Department of Forest Sciences, Colorado State University, Ft. Collins, CO 80523. J. Phillip Grime is a professor in the Unit of Comparative Plant Ecology, The University of Sheffield, Sheffield S10 2TN, UK. William K. Lauenroth is a professor in the Rangeland Ecosystem Science Department, Natural Resource Ecology Laboratory, Colorado State University, Ft. Collins, CO 80523. Amanda Lombard is a research scientist at the FitzPatrick Institute, University of Cape Town, Cape Town, 7700 South Africa. Harold A. Mooney is a professor in the Department of Biological Sciences, Stanford University, Stanford, CA 94305. Arvin R. Mosier is a research scientist in the USDA Agricultural Research Service, P. O. Box E, Ft. Collins, CO 80522. Shahid Naeem is an assistant professor and David Tilman is a professor in the Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108. Stephen W. Pacala is a professor in the Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544. Jacques Roy is director of research at the Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, F-34293 Montpellier Cedex 5, France. William L. Steffen is executive officer of GCTE, CSIRO, Division of Wildlife and Ecology, Lyneham ACT 2602, Australia. Changes in biodiversity can have significant