Bioregion
A bioregion is a geographical area, on land or at sea, defined not by administrative boundaries but by distinct characteristics such as plant and animal species, ecological systems, soils and landforms, human settlements and cultures those attributes give rise to, and topographic features such as watersheds. The idea of bioregions were adopted and popularized in the mid-1970s by a school of philosophy called Bioregionalism, which includes the concept that human culture, in practice, can influence bioregional definitions. Bioregions are part of a nested series of ecological scales, generally starting with local watersheds, growing into larger river systems, then Level III or IV Ecoregions (or regional ecosystems), bioregions, then biogeographical Realm, followed by the continental-scale and ultimately the biosphere. Within the life sciences, there are numerous methods used to define the physical limits of a bioregion based on the spatial extent of mapped ecological phenomena -- from Species Distributions and hydrological systems (i.e. Watersheds) to topographic features (e.g.