Bioregional Vocabulary

A biogeographic realm is the broadest biogeographic division of Earth’s land surface, based on distributional patterns of terrestrial organisms.

They are subdivided into bioregions, which are further subdivided into ecoregions.

A biogeographic realm is also known as “ecozone”, although that term may also refer to ecoregions.

Biogeographic Realm on Wikipedia

A bioregion is an ecologically and geographically defined area that is smaller than a biogeographic realm, but larger than an ecoregion or an ecosystem, in the World Wide Fund for Nature classification scheme.

There is also an attempt to use the term in a rank-less generalist sense, similar to the terms “biogeographic area” or “biogeographic unit”.[1]

It may be conceptually similar to an ecoprovince.[2]

It is also differently used in the environmentalist context, being coined by Berg and Dasmann (1977).[3][4]

Bioregion on Wikipedia

Madrean Sky Islands Bioregional Marine Sanctuary

An ecoregion (ecological region) 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 florafauna 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 (largely undefined at this point). Ecoregions are also known as “ecozones” (“ecological zones”), although that term may also refer to biogeographic realms.

Ecoregion on Wikipedia


An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact.[2]: 458

Ecosystems are controlled by external and internal factors. External factors such as climateparent material which forms the soil and topography, control the overall structure of an ecosystem but are not themselves influenced by the ecosystem. Internal factors are controlled, for example, by decomposition, root competition, shading, disturbance, succession, and the types of species present. 

Ecosystem on Wikipedia

Colorado River Bioregional Marine Sanctuary

A biome (/ˈb.m/) is a biogeographical unit consisting of a biological community that has formed in response to the physical environment[1] in which they are found and a shared regional climate.[2][3][4]

Biomes may span more than one continent. Biome is a broader term than habitat and can comprise a variety of habitats.

Biome on Wikipedia

Skagit Bioregional Watershed Community

In ecology, habitat refers to the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species.

A species habitat can be seen as the physical manifestation of its ecological niche. Thus “habitat” is a species-specific term, fundamentally different from concepts such as environment or vegetation assemblages, for which the term “habitat-type” is more appropriate.[2]

Habitat on Wikipedia

Baja Bioregional Marine Sanctuary

An ecotone is a transition area between two biological communities,[1] where two communities meet and integrate.[2]

It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and grassland ecosystems).[3]

An ecotone may appear on the ground as a gradual blending of the two communities across a broad area, or it may manifest itself as a sharp boundary line.

Ecotone on Wikipedia