ecosystem type

Ecosystems can be classified according to various criteria: e.g. from the point of view of energy source, two major types of ecosystems can be distinguished. Autotrophic ecosystems have primary producers as a principal component and sunlight has the major initial energy source; etherotrophic ecosystems depend upon preformed organic matter that is imported from autotrophic ecosystems elsewhere. Ecosystems can also be classified in terrestrial, marine and freshwater. In European nature policy a further classification into habitats is widely used.