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.
David Tilman is Regents' Professor and McKnight Presidential Chair in Ecology at the University of Minnesota, and is Director of the University’s Cedar Creek Ecosystem Science Reserve. He is an elected member of the American Academy of Arts and Sciences and the National Academy of Sciences, was the Founding Editor of the journal Ecological Issues and has served on editorial boards of nine scholarly journals, including Science. He serves on the Advisory Board for the Max Plank Institute for Biogeochemistry in Jena, Germany. He has been a Member of the Institute for Advanced Study in Princeton and a Fel ow of the National Center for Ecological Analysis and Synthesis.
He has received the Ecological Society of America’s Cooper Award and its MacArthur Award, the Botanical Society of America’s Centennial Award, the Princeton Environmental Prize and was named a J. S. Guggenheim Fellow. He has written two books, edited three books, and published more than 200 papers in the peer-reviewed literature, including more than 30 papers in Science, Nature and the Proceedings of the National Academy of Sciences USA. The Institute for Scientific Information designated him as the world’s most highly cited environmental scientist of the decade for 1990-2000 and for 1996-2006.
His multifaceted interests in biodiversity have given his research a broad focus, including
(1) The forces that have al owed numerous competing species to evolve, coexist and persist in natural and managed ecosystems,
(2) The ways that human actions threaten this biodiversity,
(3) The impacts of the loss of biodiversity on ecosystem functioning and on ecosystem services of benefit to society
(4) The benefits that the preservation and restoration of biodiversity can provide.
His current research explores ways to use biodiversity as a tool for biofuel production and climate stabilization through carbon sequestration. His work on biodiversity and stability of grassland ecosystems (published in Nature in 1994) chal enged the established paradigm and led the discipline to re-examine how diversity affects the productivity, stability and nutrient efficiency of ecosystems. His biodiversity field experiments and related mathematical theory, reported in a series of papers in Science, Nature and other journals, are providing a more rigorous foundation for managing ecosystems to maximize the ecosystem services that can provide to society.
His work on sustainable agriculture and renewable energy has critical y examined the ful 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. He showed that restored native high-diversity grasslands could provide more energy per hectare than corn grain ethanol or soybean biodiesel, be far better for the environment through carbon sequestration, and prevent competition between food crops and biofuel crops for fertile land.
Recent work has shown that biofuel production based on clearing and/or converting old growth forests could become a major global threat to biodiversity, have greater greenhouse gas impact than gasoline, and compromise global food supplies.
David Tilman has also dedicated much of his career to communicating with the public, politicians and the managers of earth’s ecosystems so that they might be better informed about environmental science and its relevance to society and to sustaining, for the long-term, the quality of human life on earth.
Agricultural Expansion and Environmental Sustainability
Sustainable supplies of food and energy, and a livable, sustainable environment, are essential requisites and rights of humanity. However, unless food and energy production and use patterns undergo dramatic transformations, these three human needs will come into increasingly strong conflict during the next 50 years. Global population and per capita income are on trajectories to increase by 50% and 40%, respectively, within the next 50 years, causing global demand for both food and energy to more than double. More than 5 billion hectares of land are currently dedicated to crops and pastures. The composition of diets is shifting with increasing incomes in ways that may require more fertile land per capita. Crop yield gains continue to depend on greater inputs of fertilizers and other agrichemicals. Fertile lands are also increasingly used to produce biofuels. If these trends and relationships continue, at least 1 billion hectares, and perhaps as much as 2 billion hectares, of natural ecosystems may be converted to croplands producing food and biofuels. Such land conversion would accelerate climate change through the release of globally significant amounts of greenhouse gasses, and greatly increase the number of species, especially those of tropical ecosystems, that are threatened with extinction. The increased use of fertilizers and pesticides would degrade freshwater ecosystems, aquifers, and coastal marine ecosystems, increasing the size and number of marine ‘dead zones.’
Solutions to these problems must address various aspects of the foodâ€energyenvironment dilemma. If diets shift to favor efficientlyâ€produced protein, global food demand could be moderated over the next 50 years, while still providing nutritionallyâ€sound diets. Longâ€term investment in increasing the yields and fertilizerâ€efficiency of fruit, vegetable and cereal crops could greatly decrease the amount of land converted to agriculture and reduce the impacts of crop production on aquatic resources. Investments made towards increasing the protein efficiency of grainâ€fed livestock and fish aquaculture would provide similar benefits. Biofuel production should focus on wastes and perennial, multispecies biomass crops grown on degraded lands of low agricultural utility, and not convert foodstuffs into fuels. Food, energy and environment are now inextricably linked, and global lands must be managed to optimize the total net food, energy and environmental benefits that these systems provide to society.