Ecology

Early ecology recognized living (biotic) and nonliving (abiotic) aspects of nature but conventionally treated them separately. Environment acted on organisms, and organisms reacted on environment, according to Clements's familiar usage. The term ecosystem was coined by the British ecologist Arthur S. Tansley in 1935 to treat organisms and environment as a unit system. Tansley defined ecosystem as the whole system (in the sense of physics) including not only the organism complex, but also the whole complex of physical factors forming what we call the environment of the biome—the habitat factors in the widest sense.

Tansley's concept was particularly useful in aquatic ecology. It was used by Raymond Lindeman (1942) in a pioneer study of a lake ecosystem. Lindeman adapted the familiar food-chain, or trophic-structure concept of ecology and emphasized the energy and nutrient relations in a pyramid of production diminishing at higher levels and relating it to a succession of lakes. A major stimulus to ecosystem ecology was the influential textbook by Eugene Odum, Fundamentals of Ecology (1953).

The ecosystem concept was widely hailed as a new ecology in the 1970s, particularly when designated as "systems" ecology, which changed the emphasis in ecology from organisms to "ecoenergetics," the flux of energy in the ecosystem, along with the flow of chemicals through the ecosystem. Systems ecology flourished as ecology was turned into "big biology" by its first venture into heavily funded research in an International Biological Program (IBP) principally directed to formulating mathematical models of large-scale ecosystems. Another approach to ecosystems was the Hubbard Brook Program, begun in 1963, an intensive program of studies of a forested watershed, which examined nutrient flow and biomass accumulation. The program used computer simulations to model the complexity of natural ecosystems.

Opinions as to the merits of systems ecology in its philosophical and mathematical format vary, but the ecosystem persists as a major aspect of ecology and is frequently cited in the conservation, environmental, and even economic and political arenas. It is widely considered as producing ecosystem services, the valuable consequences of the multitudinous activities performed by biological systems to the great advantage of humans and often in spite of them. In 1988 "ecosystem" was designated "most important ecological concept" in a survey of members of the British Ecological Society, and it remains significant today.