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单词 ecosystem
释义
ecosystem

Biology
  • A biological community and the physical environment associated with it. Ecosystems seldom have discrete boundaries, and they can range in scale from a rotting log to an entire forest. Nutrients pass between the different organisms in an ecosystem in definite pathways; for example, nutrients in the soil are taken up by plants, which are then eaten by herbivores, which in turn may be eaten by carnivores (see food chain). Organisms are classified on the basis of their position in an ecosystem into various trophic levels. Nutrients and energy move round ecosystems in loops or cycles (in the case above, for example, nutrients are returned to the soil via animal wastes and decomposition). See carbon cycle; nitrogen cycle.

    https://www.millenniumassessment.org/en/index.html The latest Millennium Ecosystem Assessment Reports commissioned by the United Nations


Geology and Earth Sciences
  • Term first used by A. G. Tansley (1935) to describe the interdependence of species in the living world (the biome or community) with one another and with their non-living (abiotic) environment. Fundamental concepts include the flow of energy via food-chains and food-webs, and the cycling of nutrients biogeochemically (see biogeochemical cycle). Ecosystem principles can be applied at all scales—thus principles that apply to an ephemeral pond, for example, apply equally to a lake, an ocean, or the whole planet. In Russian and central European literature ‘biogeocoenosis’ describes the same concept.


Geography
  • A community of plants and animals within a particular physical environment that is linked by a flow of materials through the non-living (abiotic) as well as the living (biotic) sections of the system. In practice, the hierarchy is: cell, organism, population, community, ecosystem, landscape, biome, and biosphere, although T. Allen and T. Hoekstra (1992) point out that this hierarchy incorporates conceptionally different, non-homogeneous levels of organization, and should therefore be regarded with suspicion. Seastedt et al. (2008) ESA Online J., DOI: 10.1890/070046, suggest that the focus in ecosystem management should be less on restoring ecosystems to their original state and more on sustaining new, healthy ecosystems that are resilient to further environmental change.


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