ecoregion

thumb|A map of the Amazon rainforest, which is composed of multiple ecoregions. The yellow line encloses the ecoregions within the Amazon per the [[World Wide Fund for Nature.]]

Ecoregions (ecological regions) are ecological and geographical areas that exist on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of ecosystems, fauna, and flora that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation (largely undefined at this point). Ecoregions are also known as "ecozones" ("ecological zones"), although that term may also refer to biogeographic realms.