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

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

, is an American

ecologist Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

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

University of Minnesota The University of Minnesota Twin Cities (historically known as University of Minnesota) is a public university, public Land-grant university, land-grant research university in the Minneapolis–Saint Paul, Twin Cities of Minneapolis and Saint ...

, 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 i ...

; Ecology, Evolution, and Behavior; and

Microbial Ecology Microbial ecology (or environmental microbiology) is a discipline where the interaction of Microorganism, microorganisms and their environment are studied. Microorganisms are known to have important and harmful ecological relationships within t ...

. 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 ...

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, United States. Tracing its roots back to 1891 as an ...

Bren School of Environmental Science & Management The UC Santa Barbara Bren School of Environmental Science and Management is the graduate environmental studies school of the University of California, Santa Barbara. The mission of the Bren School is to play a leading role in researching environ ...

Early life and education

Tilman (born Titman) was born in

Aurora, Illinois Aurora is a city in northeastern Illinois, United States. It is located along the Fox River (Illinois River tributary), Fox River west of Chicago. It is the List of municipalities in Illinois, second-most populous city in Illinois, with a popul ...

in 1949. He earned his

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

degree in

zoology Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...

in 1971 and his

PhD A Doctor of Philosophy (PhD, DPhil; or ) is a terminal degree that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the deg ...

in ecology in 1976 at the

University of Michigan The University of Michigan (U-M, U of M, or Michigan) is a public university, public research university in Ann Arbor, Michigan, United States. Founded in 1817, it is the oldest institution of higher education in the state. The University of Mi ...

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

Science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

''.

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 various benefits that humans derive from Ecosystem, ecosystems. The interconnected Biotic_material, living and Abiotic, non-living components of the natural environment offer benefits such as pollination of crops, clean ...

. 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 (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...

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, indi ...

in community structure and on the role of

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

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

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

'' 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 U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

. 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 community (ecology), ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the Abundance (ecology), abunda ...

and

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

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 Succession is the act or process of following in order or sequence. Governance and politics *Order of succession, in politics, the ascension to power by one ruler, official, or monarch after the death, resignation, or removal from office of ...

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 natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere lev ...

'' 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, indi ...

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 or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

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, endowed by the late Simon and Olga Hirsh Guggenheim. These awards are bestowed upon individuals who have demonstrated d ...

, is a Fellow of the

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is a United States–based international nonprofit with the stated mission of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsib ...

and of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) 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 other ...

, and is a member of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, 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 ...

. In 2000 Tilman was designated the ''Most Highly Cited Environmental Scientist of the Decade'' by Essential Science Indicators. *1996: Robert H. MacArthur Award *2013:

Alexander von Humboldt Medal Alexander () is a male name of Greek origin. The most prominent bearer of the name is Alexander the Great, the king of the Ancient Greek kingdom of Macedonia who created one of the largest empires in ancient history. Variants listed here are A ...

*2014: Ramon Margalef Prize in Ecology *2014:

* 2017: Elected a Foreign Member of the Royal Society (ForMemRS) *2025:

National Medal of Science The National Medal of Science is an honor bestowed by the President of the United States to individuals in science and engineering who have made important contributions to the advancement of knowledge in the fields of behavioral science, behavior ...

References

External links

* {{DEFAULTSORT:Tilman, George David Living people 1949 births American ecologists Mathematical ecologists American 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