George David Tilman (born Titman; July 22, 1949),

ForMemRS Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the judges of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural knowledge, including mathematics ...

, is an American

ecologist Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

. He is Regents Professor and McKnight Presidential Chair in Ecology at the

University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Tw ...

, as well as an instructor in

Conservation Biology Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an int ...

; Ecology, Evolution, and Behavior; and

Microbial Ecology Microbial ecology (or environmental microbiology) 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 viru ...

. He is director of the

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. Name Originally t ...

long-term ecological research station. Tilman is also a professor at

University of California, Santa Barbara The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a Public university, public Land-grant university, land-grant research university in Santa Barbara County, California, Santa Barbara, California with 23,196 undergraduate ...

's Bren School of Environmental Science & Management.

Early life and education

Tilman (born Titman) was born in

Aurora, Illinois Aurora is a city in the Chicago metropolitan area located partially in DuPage County, Illinois, DuPage, Kane County, Illinois, Kane, Kendall County, Illinois, Kendall, and Will County, Illinois, Will counties in the U.S. state of Illinois. Locat ...

in 1949. He earned his

Bachelor of Science A Bachelor of Science (BS, BSc, SB, or ScB; from the Latin ') is a bachelor's degree awarded for programs that generally last three to five years. The first university to admit a student to the degree of Bachelor of Science was the University of ...

degree in

zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

in 1971 and his PhD in ecology in 1976 at the

University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...

. Some of his doctoral research was published in the journal ''

Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...

''.

Career and research

In an August 2001 interview, 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 Ecosystem services are the many and varied benefits to humans provided by the natural environment and healthy ecosystems. Such ecosystems include, for example, agroecosystems, forest ecosystem, grassland ecosystems, and aquatic ecosystems. Th ...

. Tilman has performed several studies to further determine the usefulness of grasslands for utilization in

biofuel Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...

Resource competition

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

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

in community structure and on the role of

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...

in ecosystem functioning. One of his most cited articles is the 1994 ''

Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

'' article on the ''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

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...

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

species richness Species richness is the number of different species represented in an ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative a ...

and

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...

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 and the biomass data showed a strong positive

correlation In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistics ...

between the plant diversity within the community and the stability of the community as a whole supporting the diversity-stability hypothesis. "The level to which the soil solution concentration of a limiting resource is reduced by an equilibrial monoculture of a species is called R*. R* is the resource concentration a species requires for it to be able to persist in a habitat. A comparable concept, that of threshold density, exists for host-microparasite inter-actions. The species with the lowest R* for a limiting soil resource is predicted to be the superior competitor for that resource." With regards to succession he focuses on resource ratios, particularly between light and nitrogen. After a big disturbance, the pattern of succession is from high light/low nitrogen towards high nitrogen/low light environment.

Competition and biodiversity

Another article by Tilman that has received substantial citation is his 1994 ''

Ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

'' article that encompasses the idea that large numbers of species can coexist in a small habitat even when they require the same

limiting nutrient A limiting factor is a variable of a system that causes a noticeable change in output or another measure of a type of system. The limiting factor is in a pyramid shape of organisms going up from the producers to consumers and so on. A factor not l ...

(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 Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

are not as good at colonizing or reproducing. In a related paper, Tilman used this model to demonstrate the phenomenon of "

extinction debt In ecology, extinction debt is the future extinction of species due to events in the past. The phrases dead clade walking and survival without recovery express the same idea. Extinction debt occurs because of time delays between impacts on a speci ...

," which refers to the time delay between

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and the extinction of species.

Awards and honors

In 2014, he received the

BBVA Foundation Frontiers of Knowledge Award The BBVA Foundation Frontiers of Knowledge Awards () are an international award programme recognizing significant contributions in the areas of scientific research and cultural creation. The categories that make up the Frontiers of Knowledge Awards ...

in the Ecology and Conservation Biology category, for scientifically establishing the value of biodiversity, quantifying, for the first time, how it contributes to make ecosystems more productive, more resilient to invasions, and more stable in the face of perturbations such as drought. He has been a

Guggenheim Fellow Guggenheim Fellowships are grants that have been awarded annually since by the John Simon Guggenheim Memorial Foundation to those "who have demonstrated exceptional capacity for productive scholarship or exceptional creative ability in the ar ...

, is a Fellow of the

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific respons ...

and of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...

, and is a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

. In 2000 Tilman was designated the ''Most Highly Cited Environmental Scientist of the Decade'' by Essential Science Indicators. *1996:

Robert H. MacArthur Award The Robert H. MacArthur Award is a biennial prize given by the Ecological Society of America to ecologists for their pivotal contributions to their field. The acceptance speeches of many recipients have been given at the annual meeting of the soci ...

*2013:

Alexander von Humboldt Medal The International Association for Vegetation Science (IAVS) promotes contact between scientists and others interested in the study of vegetation ecology, promotes research and publication of research results. In 1939 the International Phytosocio ...

*2014:

Ramon Margalef Prize in Ecology The Ramon Margalef Prize in Ecology ( ca, Premi Ramon Margalef d'Ecologia) is a prize awarded annually by the Generalitat de Catalunya to recognize an exceptional scientific career or discovery in the field of ecology or other environmental scienc ...

*2014:

* 2017: Elected a Foreign Member of the Royal Society (ForMemRS)

References

External links

* {{DEFAULTSORT:Tilman, George David Living people 1949 births American ecologists Mathematical ecologists Environmental scientists People from Aurora, Illinois University of Michigan College of Literature, Science, and the Arts alumni University of Minnesota faculty Fellows of the American Association for the Advancement of Science Fellows of the American Academy of Arts and Sciences Members of the United States National Academy of Sciences Winners of the Heineken Prize Winners of the Ramon Margalef Prize in Ecology Fellows of the Ecological Society of America Foreign Members of the Royal Society