what is ecosystem?

Answer 1

An ecosystem, a contraction of "ecological" and "system", refers to the collection of components and processes that comprise, and govern the behavior of, some defined subset of the biosphere. The term is generally understood to refer to all biotic and abiotic components, and their interactions with each other, in some defined area, with no conceptual restrictions on how large or small that area can be. To many people, ecosystems (like any other type of system), are governed by the rules of systems science and cybernetics, as applied specifically to collections of organisms and relevant abiotic components. To others, ecosystems are primarily governed by stochastic events, the reactions they provoke on non-living materials and the corresponding responses by organisms. 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."

Ecosystems have become particularly important politically, since the Convention on Biological Diversity (CBD) - ratified by more than 175 countries - defines "the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural surroundings" as one of the binding commitments of the ratifying countries. This has created the political necessity to spatially identify ecosystems and somehow distinguish among them. The CBD defines an "ecosystem" as a "dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit". Early conceptions of an ecosystem were as a structured functional unit in equilibrium of energy and matter flows among constituent elements. Some considered this vision limited,and preferred to define an ecosystem in terms of cybernetics.

From this point of view an ecological system is a functional dynamic organization, or steady state. Steady state is understood as the phase of an ecological system's evolution when the organisms are "balanced" with each other and their environment. This balance would is regulated through various types of interactions, 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 branch of ecology that gave rise to this view has become known as systems ecology. Under this deterministic vision, 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.

Other population ecologists, stochastists, (den Boer & Reddingius, 1996), view an ecosystem as an expression of stochastic events, and corresponding responses from organisms. Thus, ecosystems result from the sums of infinite individual responses of organisms to stimuli from non-living and living elements in the environment. The presence or absence of populations merely depends on reproductive and dispersal success and population levels fluctuate in response to stochastic (chance) events. As the number of species in an ecosystem is higher, the number of stimuli is also higher.

Mathematically it can be demonstrated that greater numbers of different interacting factors, tend to dampen fluctuations in each of the individual factors. In this vision, ecosystems are not regulated and there is no balance of nature. Stochastists do recognise that certain intrinsic regulating mechanisms occur in nature. In their vision they regulate population levels, most notably through territorial behaviour. Andrewatha and Birch (1954), suggest that territorial behaviour tends to keep populations at levels where food supply is not a limiting factor. Hence, stochastists see territorial behaviour as a regulatory mechanism at the species level but not at the ecosystem level.

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Answer 2

An ecosystem is a system formed by the interaction of a community of organisms with their physical environment

Answer 3

A system formed by the interaction of organisms with their physical environment is ecosystem...