In ecology, a ecosystem indicates the unit formed by a association or community of living beings (or Biocénose) and its geological, pedological and atmospheric environment (the Biotope). The elements constituting an ecosystem develop a network of interdependences allowing the maintenance and the development of the Vie.

An ecosystem is the interaction between the biotic Facteurs and abiotic.

In the ecosystem, the role of the ground is to provide a diversity of habitats, to act like accumulator, transformer and medium of transfer for water and the other products brought.

In 2006, the authors of the evaluation of the ecosystems for the millenium explicitly integrated the Nécromasse by defining an ecosystem as a “dynamic complex composed of plants, animals, micro-organisms, and surrounding still life acting as interaction as a functional unit”

The relationship between Biosphere and écosphère is the same one as between community and ecosystem.

One can speak about natural ecosystem, naturally balanced: on each level, the biomass is stabilized thanks to the interactions with the other levels.

The term was defined by Arthur George Tansley in 1935.

Dynamic system

The ecosystem is a natural Système which tends to evolve to a theoretical state stable, known as climacic, while being capable of evolution and adaptation to the ecological and abiotic context. One speaks about ecological regression when the system evolves of a state to a less stable state. Ecosystems, as the biosphere always in an unstable state of balance, are unceasingly corrected by complexes loops of feedbacks.

Relative richness

The ecosystems contain more or less complex combinations of Espèce S. The majority of the scientists agree to say that more than 50% of the plant species and animal of the sphere are concentrated in the tropical forests. These last would have undergone less climatic variations during times, which would have made it possible the species to continue their evolution over one long period. An ecosystem is also a natural system which tends has to evolve to its most stable state.

Ecological services

See also: ecological Services

The ecosystems in addition to which they provide all oxygen that we let us breathe (the natural resource most vital, and the only one that we do not pay yet) are sources of very many " Bienfaits" for the Man, free as long as the ecosystems are preserved.

From RIO, and with the Millenium Ecosystems assessment , these ecological Services starts to be quantified, and some try to evaluate their economic value. One generally classifies them in:

  • Services of provisioning (ex: food, water, wood, fibers, matters and molecules organic, pharmaceutical molecule of interest, self-sustained genetic resources, etc)
  • Services of regulation (ex: regulation macro and microclimatic, regulation of the floods and the diseases, relative Impact strength of the ecosystems vis-a-vis the catastrophes, etc
  • Culture sections which include the nonmaterial benefit, enrichment spiritual, pleasures entertaining and cultural, the esthetic experiment and values, as well as the teaching interest offered by Nature useful for the social relations and the human formation. They what is called form also part of the environmental Aménité S.
  • Services of support , thus named because they are the condition of the maintenance of the favorable conditions to the life on Earth, with in particular the bio-géo-ecological cycles of the elements (nutritive or not). They are the buckled systems of feedbacks which are necessary to the production of all the other abundant services by the ecosystems. They contribute in particular to the maintenance of local and total ecological balances, the stability of the atmospheric production of oxygen and the total climate, the formation and the stability of the grounds, the cycle maintained the elements and the offer of habitat for all the species…

All these services depend on the Biodiversity, element-key of the autocatalytic , evolutionary and self-adapting character of the ecosystems.

One adds sometimes the to them services " ontogéniques" (" ontogénique" qualifying what is relating to the development of the individual (organization) since the fecundation of egg until the adult state) . This service are distinguished from the culture sections in the sense that at the same time the spirit and the human body developed since 3 million years with the direct contact of nature and its stimuli, and that it remains plausibly useful even necessary for human blooming and its health (immunizing in particular).

See too

External bonds

  • http://www.greenfacts.org/fr/biodiversite/index.htm#1
  • Objective Sciences: Diffusion of the scientific culture, Formation Environment

Simple: Ecosystem Zh-yue: 生態系統

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