A theory that embraces the idea of successional development to an optimum sustainable vegetation community that is in equilibrium with its environment. Two conceptual models of climax vegetation exist: monoclimax (F. E. Clements, in 1904 and 1916) and polyclimax (A. G. Tansley, in 1916 and 1920). The essential difference between them lies in the time-scale envisaged for the development of the climax. Monoclimax envisages the development of vegetation and soil toward a definite end-point controlled by climate. Many ecologists consider this approach unworkable in practice, since equilibrium can never be reached owing to variations in climate over long periods of time (e.g. the known climatic changes in historical and post-glacial times in mid-latitudes). Evidence from climatically relatively uniform and stable tropical areas shows different, equally persistent, woodland communities edaphically controlled. Insistence on a single uniform climax community for a major climatic region necessitates the introduction of an extensive terminology for subclimax communities, so tending to obscure an otherwise useful and simple concept. The alternative (polyclimax) approach proposes successional development to equilibrium with the environment, which may be controlled by climate or by some other factor (e.g. soil or fire) as often occurs in practice. See also climax community; succession.
Subjects: Plant Sciences and Forestry — Ecology and Conservation.