Wikipedia has articles relating to two separate ecoregion classification systems:
An ecoregion is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems 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 . Ecoregions are also known as "ecozones", although that term may also refer to biogeographic realms.
The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface.
The ecology of California can be understood by dividing the state into a number of ecoregions, which contain distinct ecological communities of plants and animals in a contiguous region. The ecoregions of California can be grouped into four major groups: desert ecoregions, Mediterranean ecoregions, forested mountains, and coastal forests.
British Columbia mainland coastal forests is a temperate coniferous forest ecoregion the Pacific coast of North America, as defined by the World Wildlife Fund (WWF) categorization system.
Poland is part of four terrestrial ecoregions, one freshwater ecoregion, and one marine ecoregion.
The Western Great Lakes forests is a terrestrial ecoregion as defined by the World Wildlife Fund. It is within the temperate broadleaf and mixed forests biome of North America. It is found in northern areas of the United States' states of Michigan, Wisconsin and Minnesota, and in southern areas of the Canadian province of Manitoba and northwestern areas of the province of Ontario.
The Southern Great Lakes lowland forests is a temperate broadleaf and mixed forest ecoregion of North America, as defined by the World Wildlife Fund. Located near the Great Lakes, it lies mostly in the central northeastern United States and extends into southeast central Canada. In modern times, little of it remains intact due to land use, including agriculture and urban uses.
Puget lowland forests is a temperate coniferous forest ecoregion the Pacific coast of North America, as defined by the World Wildlife Fund (WWF) categorization system.
Pacific Coastal Mountain icefields and tundra is a tundra ecoregion in Alaska, British Columbia, and Yukon, as defined by the World Wildlife Fund (WWF) categorization system.