G.David Tilman (NAS) is Regents Professor and director of the Cedar Creek Natural History Area at the University of Minnesota. He received his Ph.D. in 1976 from the University of Michigan. He is a member of the National Academy of Sciences. He is one of the world’s leading ecologists, blending theoretical and experimental work seamlessly. His classic research created the benchmark model for determining how different organisms within an ecosystem compete for resources, and his field experiments and theoretical insights have helped to alert scientists to the fact that the reduction in the number of plant and animal species on the planet has a profound effect on the way the earth’s ecosystems function. He has been a member of numerous NRC studies and was a member of the Proceedings of the National Academy of Sciences Editorial Board and the Board on Environmental Studies and Toxicology.