The Ecosystem: Superorganism, or Collection of Individuals ?

International audienceThe nature of the ecosystem has been a matter of debate since its incep-tion. When Tansley (1935) first defined the ecosystem concept, he did so in opposition to the then prevailing view of Clements (1916), who conceived plant communities as superorganisms; i.e., as higher-level bio-logical entities that have properties of functional organization similar to those of individual organisms (Wilson and Sober 1989). According to Cle-ments, plant communities develop regularly to a climax, just as do indi-vidual organisms to their adult stage during ontogeny. Although Tansley rejected Clements’s superorganismic view, he did recognize a signifi-cant amount of organization in communities and ecosystems; he went as far as saying that “mature well-integrated plant communities . . . had enough of the characters of organisms to be considered as quasi- organisms, in the same way that human societies are habitually so considered [em-phasis in the original]” (Tansley 1935, pp. 289–290). In contrast, Gleason developed an explicitly individualistic view of plant associations, which he regarded as the mere product of “the coincidence of environmental se lection and migration over an area of recognizable extent” (Gleason 1926, p. 26)