History of the Ecosystem Concept

Systems concepts of the environment have long played a role in the development of ecology as a discipline, but these came to a head in the early twentieth century. During this period, the two dominant and competing ecological paradigms were the organismic (e.g., Clements) and individualistic (e.g., Gleason) views. The organismic approach held that communities and ecosystems were discernible objects that had an inherent and organized complexity resulting in a cybernetic and self-governing system, similar in ways to how an organism regulates itself.The individualistic approach held that communities had observer-dependent boundaries and internal development was stochastic and individual. In this paradigm, the internal relations were synergistic, but not cybernetic since the individual parts functioned independently. The organismic ideas grew out of the functional understanding of whole systems such as lakes, and also out of the discussions involving how communities changed over time during succession. These ideas were influenced by philosophers of the day such as Jan Smuts. This was particularly true of German holists, such as the limnology group at the Kaiser-Wilhelm-Instituts in Plon led by Thienemann, and others such as Leick (plant ecology) and Friedrich (zoology). Table 2 shows a summary of some of the main ecosystem and related concepts. This dialog between the holists and reductionists affected the main currents of ecological thought during this period, and it was in part resolved by the introduction of 'ecosystem', which is both physical in nature and also systemic.

The term ecosystem, which is ubiquitous today, both as scientific terminology and in common vernacular, grew out of this climate. It was first used by Arthur Tansley in 1935 in a seminal paper in the journal Ecology, entitled 'The use and abuse of vegetational concepts and terms'. In fact, his reason for coining the term 'ecosystem' was in response, as the title says, to a perceived abuse of community concepts by some such as Clements and Cowles. While Tansley himself brought a systems perspective, the community as organism metaphor bothered him to the extent that he wanted to provide a more scientific footing for the processes and interactions occurring during community development. Tansley describes the ecosystem thus, ''... the fundamental conception is... the whole system, 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.'' The definition he proposed over 70 years ago sounds fresh today, since it has changed little if at all. The major tenets of this approach are the explicit inclusion of abiotic processes interacting with the biota - in this sense it is more along the Haeckelian lines of ecology than the Darwinian, with an additional emphasis on the system. The latter tied the field closely to the burgeoning disciplines of general system theory and systems analysis.

While the conceptual underpinning of the ecosystem was now established, the introduction of this term was

Table 2 Ecosystem and related concept

Year

Term

Author

Concept

1887

Microcosm

Forbes

Broadening of the biocoenosis concept

1914

Ecoid

Negri

Unholistic, based on Gleasonian ideas

1928

(├ľkologisches system

Woltereck

Still being used to avoid argument

1930

Holocoen

Friedrich

Holistic, biologistic

1935

Ecosystem

Tansley

Antiholistic, physicalist

1939

Biosystem

Thienemann

Stressing functional organization

1944

Geobioconose

Sukacev

Geographic, landscape ecological

1944

Bioinert body

Vernadsky

Biogeochemical

1948

Biochore

Pallmann

Landscape ecological

1950

Landschaft

Troll

Holistic, 'Gestalt' viewing

Modified from Wiegleb G (2000) Lecture Notes on The History of Ecology and Nature Conservation.

Modified from Wiegleb G (2000) Lecture Notes on The History of Ecology and Nature Conservation.

theoretical, lacking guidance as to how it might be applied as a field of study. There were around this time several whole system energy budgets being developed, particularly for lake ecosystems by North American ecologists such as Forbes, Birge, andJuday in Wisconsin, and which were ideal test cases for the ecosystem concept. Building on this work, in 1942, Lindeman's study of Cedar Bog Lake also in Wisconsin was published, providing, for the first time, a clear application of the ecosystem concept. In addition to constructing the food cycle of the aquatic system, he developed a metric - now called the Lindeman efficiency - to assess the efficiency of energy movement from one trophic level to the next based on ecological feeding relations. His conceptual model of Cedar Bog Lake included passive flows to detritus, but these were not included in the trophic enumeration. Since then numerous additional studies have followed this same approach and it has been applied to many habitats such as terrestrial, aquatic, and urban ecosystems.

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