G. David Tilman born in 1949 in Aurora, Illinois

Aurora, Illinois

Aurora is the second most populous city in the U.S. state of Illinois, and the 112th largest city in the United States. A suburb of Chicago, located west of the Loop, its population in 2010 was 197,899. Originally founded within Kane County, Aurora's city limits have expanded greatly over the past...

, is a prominent American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 ecologist who earned his Ph.D. at the University of Michigan

University of Michigan

The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...

 in 1976. He is Regent's Professor and McKnight Presidential Chair in Ecology at the University of Minnesota

University of Minnesota

The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...

, as well as an instructor in Conservation Biology

Conservation biology

Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...

; Ecology

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

, Evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

, and Behavior; and Microbial ecology

Microbial ecology

Microbial ecology is the ecology of microorganisms: their relationship with one another and with their environment. It concerns the three major domains of life — Eukaryota, Archaea, and Bacteria — as well as viruses....

. He is director of the Cedar Creek Ecosystem Science Reserve

Cedar Creek Ecosystem Science Reserve

The Cedar Creek Ecosystem Science Reserve is an ecological research site located primarily in East Bethel, Minnesota in the counties of Anoka and Isanti on the northern edge of the Minneapolis-Saint Paul metropolitan area...

 Long-term Ecological Research station. Tilman has been a Guggenheim Fellow, is a Fellow of the American Association for the Advancement of Science

American Association for the Advancement of Science

The American Association for the Advancement of Science is an international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the...

 and of the American Academy of Arts and Sciences

American Academy of Arts and Sciences

The American Academy of Arts and Sciences is an independent policy research center that conducts multidisciplinary studies of complex and emerging problems. The Academy’s elected members are leaders in the academic disciplines, the arts, business, and public affairs.James Bowdoin, John Adams, and...

, and is a member of the National Academy of Science. In 2000 Tilman was designated the Most Highly Cited Environmental Scientist of the Decade by Essential Science Indicators. In 2008, Tilman was awarded the International Prize for Biology

International Prize for Biology

The International Prize for Biology is an annual award for significant contributions to biology. The award was created in 1985 to recognize Emperor Hirohito of Japan's long time interest in and support of the biological sciences. The selection and award of the prize is managed by the Japan Society...

.

Ecology interests

In an August 2001 interview, Dr. Tilman states that his passion with ecology stems from his love for both math and biology, and ecology is a field that allows him to express both together along with his love for the outdoors. His work explores how both natural and managed ecosystems can be used to meet the needs of humans, whether it be for food, energy, or ecosystem services. Dr. Tilman has performed several studies to further determine the usefulness of grasslands for utilization in biofuel

Biofuel

Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...

.

Resource competition & community structure

Dr. Tilman is best known for his work on the role of resource competition

Competition (biology)

Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both is required. Competition both within and between species is an important topic in ecology, especially community ecology...

 in community structure and on the role of biodiversity

Biodiversity

Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

 in ecosystem functioning. One of his most cited articles is the 1994 Nature article titled "Biodiversity and stability in grasslands" which provided data regarding an experiment that began in 1982 with more than 200 plots in a grassland field in the Cedar Creek National History Area in Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

. Each of these plots was continuously monitored for 20 years for factors such as species richness

Species richness

Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...

 and biomass

Biomass

Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

 created by the community. Tilman’s article looked at data both prior to and following a drought on the grassland plots in 1988, which provided surprising results. The drought provided substantial disturbance

Disturbance

In ecology, a disturbance is a temporary change in average environmental conditions that causes a pronounced change in an ecosystem. Outside disturbance forces often act quickly and with great effect, sometimes resulting in the removal of large amounts of biomass...

 and the biomass data showed a strong positive correlation

Correlation

In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....

 between the plant diversity within the community and the stability of the community as a whole supporting the diversity-stability hypothesis

Ecological effects of biodiversity

The diversity of species and genes in ecological communities affects the functioning of these communities. These ecological effects of biodiversity in turn affect both climate change through enhanced greenhouse gases, aerosols and loss of land cover, and biological diversity, causing a rapid loss...

.

Competition & biodiversity in spatially structured habitats

Another article by Tilman that has received substantial citation is his 1994 Ecology article that encompasses the idea that large numbers of species can coexist in a small habitat even when they require the same limiting nutrient (such as nitrogen), as long as there is a tradeoff between the species. Basically it means that they can coexist because species that are good competitors are not as good at colonizing or reproducing. In a related paper, Tilman used this model to demonstrate the phenomenon of "extinction debt

Extinction debt

Extinction debt is a concept in ecology that describes the future extinction of species due to events in the past. Extinction debt occurs because of time delays between impacts on a species, such as destruction of habitat, and the species' ultimate disappearance...

," which refers to the time delay between habitat destruction and the extinction of species.