Ecosystem

In ecology, the word ecosystem is an abbreviation of the term, ecological system. Some consider this the basic unit in ecology. Ecosystems are not to be confused with biomes because they are smaller than biomes. They can be as big as the sahara desert, but as small as a pond.

In general terms an ecological system can be thought of as an assemblage of organisms (plant, animal and other living organisms—also referred to as a biotic community or biocoenosis) living together with their environment (or biotope), functioning as a loose unit. That is, a dynamic and complex whole, interacting as an "ecological unit".

Early conceptions of this unit were as a structured functional unit in equilibrium. This equilibrium was characterized by energy and matter flows between its constituent elements. Others considered this vision limited, and preferred to understand an ecosystem in terms of cybernetics. From this view an ecological system is not a structured functional unit in equilibrium, but a functional organisation at dynamic equilibrium, or what was also called steady state. The branch of ecology that gave rise to this view has become known as Systems Ecology. Steady state is understood as the phase of an ecological systems evolution when the organisms are "balanced" with each other and their environment. This balance is achieved through various types of symbiosis, such as predation, parasitism, mutualism, commensalism, competition, and amensalism. Introduction of new elements, whether abiotic or biotic, into an ecosystem tend to have a disruptive effect. In some cases, this can lead to ecological collapse and the death of many native species. The abstract notion of ecological health attempts to measure the robustness and recovery capacity for an ecosystem. That is, how far the ecosystem is away from steady state.

The size and scale of an ecosystem can vary widely. It may be a whole forest, as well as a small pond, or even the geobiosphere itself. Different ecosystems are often separated by geographical barriers, like deserts, mountains or oceans, or are isolated otherwise, like lakes or rivers. As these borders are never rigid, ecosystems tend to blend into each other. As a result, the whole earth can be seen as a single ecosystem, or a lake can be divided into several ecosystems, depending on the scale used.

History

The term ecosystem first appeared in a 1935 publication by the British ecologist Arthur Tansley (Tansley, 1935). However, the term had been coined already in 1930 by Tansley's colleague Roy Clapham, who was asked if he could think of a suitable word to denote the physical and biological components of an environment considered in relation to each other as a unit. Tansley expanded on the term in his later work, adding the ecotope concept to define the spatial context of ecosystems (Tansley, 1939). Modern usage of the term derives from the work of Raymond Lindeman in his classic study of a Minnesota lake (Lindeman, 1942). Lindeman's central concepts were that of functional organisation and ecological energy efficiency ratios. This approach is connected to ecological energetics and might also be thought of as environmental rationalism. It was subsequently applied by H.T.Odum, sometimes called the 'father' of ecosystems ecology, in founding the transdiscipline known as Systems Ecology.

See also

• Pond ecosystem
• Aquatic ecosystem
• Biogeochemical cycle
• Biome
• Biosphere
• Biosphere 2
• Corporate Ecosystem
• Ecological yield
• Ecosystem ecology
• Ecotope
• Ecotourism
• Edge effect
• Eugene Odum
• Food chain
• Hypolith
• Invasive species
• Landscape ecology
• Media ecosystem
• Overfishing
• Trophic level
• Systems Ecology

External links

• Teaching about Ecosystems
• Millennium Ecosystem Assessment (2005)
• A popularized version of the Millennium Ecosystem Assessment by GreenFacts.
• Bering Sea Climate and Ecosystem - current status
• Arctic Ecosystems and Climate: A Near Realtime Arctic Change website

References

• Lindeman, R. L. 1942. The trophic-dynamic aspect of ecology. Ecology 23: 399-418.
• Tansley, A. G. 1935. The use and abuse of vegetational concepts and terms. Ecology 16: 284-307.

• Tansley, A.G. 1939. The British Islands and their Vegetation. Volume 1 of 2. University Press, Cambridge, Cambridge, United Kingdom. 484 pg.