In ecology, an integrated unit consisting of the community of living organisms and the nonliving, or physical, environment in a particular area. The relationships among species in an ecosystem are usually complex and finely balanced, and removal of any one species may be disastrous. The removal of a major predator, for example, can result in the destruction of the ecosystem through overgrazing by herbivores.
Ecosystems can be identified at different scales—for example, the global ecosystem consists of all the organisms living on Earth, the Earth itself (both land and sea), and the atmosphere above; a freshwater-pond ecosystem consists of the plants and animals living in the pond, the pond water and all the substances dissolved or suspended in that water, and the rocks, mud, and decaying matter that make up the pond bottom.
Energy and nutrients pass through organisms in an ecosystem in a particular sequence (see food chain): energy is captured through photosynthesis, and nutrients are taken up from the soil or water by plants; both are passed to herbivores that eat the plants and then to carnivores that feed on herbivores. These nutrients are returned to the soil through the decomposition of excrement and dead organisms, thus completing a cycle that is crucial to the stability and survival of the ecosystem.
A system formed by the interaction of a community of organisms with their physical environment.
Prirodna zajednica živih organizama i neživih materija na nekom određenom prostoru (grč.)