David Tilman's research focuses on the causes, consequences, and conservation of Earth’s biodiversity, and on how managed and natural ecosystems can sustainably meet human needs for food, energy, and ecosystem services. His current research explores ways to use biodiversity as a tool for biofuel production and climate stabilization through carbon sequestration. His work on sustainable agriculture and renewable energy has critically examined the full environmental, energetic, and economic costs and benefits of grain crops, of current food-based biofuels, and of biofuels made from diverse mixtures of prairie grasses and other native plants growing on already-degraded lands.