Clements, Frederic Edward

Frederic Edward Clements, (born Sept. 16, 1874, Lincoln, Neb., U.S.—died July 26, 1945, Santa Barbara, Calif.), American botanist, taxonomist, and ecologist who influenced the early study of plant communities, particularly the process of plant succession.

Clements was educated at the University of Nebraska, where he studied under the influential American botanist Charles E. Bessey. Clements received an undergraduate degree in 1894, a master’s degree in botany in 1896, and a Ph.D. in botany in 1898. Although deeply committed to agricultural problems, Bessey was also a leading proponent of the “new botany,” which emphasized microscopy, plant physiology, and laboratory experimentation. These approaches had a profound impact on Clements’s intellectual development. Together with Roscoe Pound, another of Bessey’s students who later became a distinguished legal scholar, Clements wrote The Phytogeography of Nebraska (1898). This broad survey of plants and plant communities served as the joint doctoral thesis for Pound and Clements, and it introduced some of the ecological techniques that Clements later perfected.

Early in his career, Clements adopted the “organicism” that English sociologist and philosopher Herbert Spencer, American sociologist Lester Frank Ward, and other 19th-century social thinkers had used to describe human societies. Clements claimed that plant communities were “complex organisms” that could be studied experimentally with the same rigour that physiologists applied to individual organisms in the laboratory. While serving as a botany professor at the University of Nebraska, Clements outlined this organismal idea in Research Methods in Ecology (1905), a work that also served as a manifesto for the new science of plant ecology.

During his tenure at the University of Minnesota between 1907 and 1917, Clements presented a much more detailed account of the organismal concept in his most influential work, Plant Succession: An Analysis of the Development of Vegetation (1916). Clements described plant succession as a developmental process through which the community underwent a well-defined series of stages that ultimately resulted in a mature, or climax, community. The climax community was both an indicator and expression of the climatic conditions that determined it. As both a broad overview of earlier research and a systematic theoretical statement, Plant Succession defined a major area of research that became a central focus of plant ecology prior to World War II.

Largely due to the success of that book, the Carnegie Institution of Washington appointed Clements a full-time research associate, a position he held from 1917 to 1941. Clements successfully used the position to improve the laboratory he had founded in 1900 near Pikes Peak, Colo., where he worked during the summer. He worked at the Carnegie Institution’s lab in Tucson, Ariz., during the winters. After he and his wife moved to Santa Barbara, Calif., in 1925, he continued his summer research at the Pikes Peak lab but worked at a lab in Santa Barbara during subsequent winters.

Support from the Carnegie Institution also provided Clements with opportunities for developing new lines of research, notably experimental taxonomy. For Clements, experimental taxonomy meant using transplant experiments and other ecological methods to investigate evolutionary processes and to improve the classification of plants. Together with American botanist Harvey Monroe Hall, Clements wrote an influential introduction to this interdisciplinary area of research, The Phylogenetic Method in Taxonomy: The North American Species of Artemisia, Chrysothamnus, and Atriplex (1923). Unlike Hall, who was a Darwinian (a proponent of evolution by natural selection), Clements believed that new plant species arose through the inheritance of acquired traits. He claimed that he had experimentally produced new species at his laboratory near Pikes Peak; however, he never fully documented that claim.

Criticism of his research, as well as personality conflicts, eroded Clements’s status within the Carnegie Institution of Washington. As a result, Hall gained control of research in experimental taxonomy at the institution by the end of the 1920s. Experimental taxonomy went on to become an important focus of ecological research, but it was Hall’s Darwinian approach combining genetics, ecology, and taxonomy to study local adaptation, rather than Clements’s adherence to the inheritance of acquired traits, that became widely accepted by ecologists after World War II.