Bioregion

A bioregion is an ecologically and geographically defined area that is smaller than a biogeographic realm, but larger than an ecoregion or an ecosystem, and is defined along watershed and hydrological boundaries. People are counted as an integral part of the definition of a bioregion.

A key difference between an ecoregions and biogeography and the term bioregion, is that while ecoregions are based on general biophysical and ecosystem data, human settlement and cultural patterns play a key role for how a bioregion is defined. A bioregion is defined along watershed and hydrological boundaries, and uses a combination of bioregional layers, beginning with the oldest "hard" lines; geology, topography, tectonics, wind, fracture zones and continental divides, working its way through the "soft" lines: living systems such as soil, ecosystems, climate, marine life, and the flora and fauna, and lastly the "human" lines: human geography, energy, transportation, agriculture, food, music, language, history, indigenous cultures, and ways of living within the context set into a place, and it's limits to determine the final edges and boundaries. This is summed up well by David McCloskey, author of the Cascadia Bioregion map: "An bioregion may be analyzed on physical, biological, and cultural levels. First, we map the landforms, geology, climate, and hydrology, and how these environmental factors work together to create a common template for life in that particular place. Second, we map the flora and fauna, especially the characteristic vegetative communities, and link them to their habitats. Third, we look at native peoples, western settlement, and current land-use patterns and problems, in interaction with the first two levels."

A bioregion is defined as the largest physical boundaries where connections based on that place will make sense. The basic units of a bioregion are watersheds and hydrological basins, and a bioregion will always maintain the natural continuity and full extent of a watershed. While a bioregion may stretch across many watersheds, it will never divide or separate a water basin. There is also an attempt to use the term in a rank-less generalist sense, similar to the terms "biogeographic area" or "biogeographic unit". It may be conceptually similar to an ecoprovince.