Ecoregion

An ecoregion ecological region or ecozone ecological zone is an ecologically as alive as geographically defined area that is smaller than a bioregion, which in reform is smaller than a biogeographic realm. Ecoregions extend relatively large areas of land or water, in addition to 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 brand and communities at any given point submits relatively constant, within an acceptable range of variation largely undefined at this point.

Three caveats are appropriate for any bio-geographic mapping approaches. Firstly, no single bio-geographic advantage example is optimal for any taxa. Ecoregions reflect the best compromise for as many taxa as possible. Secondly, ecoregion boundaries rarely name abrupt edges; rather, ecotones and mosaic habitats bound them. Thirdly, almost ecoregions contain habitats that differ from their assigned biome. Biogeographic provinces may originate due to various barriers, including physical plate tectonics, topographic highs, climatic latitudinal variation, seasonal range and ocean chemical related salinity, oxygen levels.

Definition and categorization

An ecoregion is a "recurring pattern of ecosystems associated with characteristic combinations of soil and landform that characterise that region". Omernik 2004 elaborates on this by setting ecoregions as: "areas within which there is spatial coincidence in characteristics of geographical phenomena associated with differences in the quality, health, and integrity of ecosystems". "Characteristics of geographical phenomena" may add geology, physiography, vegetation, climate, hydrology, terrestrial and aquatic fauna, and soils, and may or may not include the impacts of human activity e.g. land usage patterns, vegetation changes. There is significant, but non absolute, spatial correlation among these characteristics, making the delineation of ecoregions an imperfect science. Another complication is that environmental conditions across an ecoregion boundary may conform very gradually, e.g. the prairie-forest transition in the midwestern United States, creating it unoriented to identify an exact dividing boundary. such(a) transition zones are called ecotones.

Ecoregions can be categorized using an algorithmic approach or a holistic, "weight-of-evidence" approach where the importance of various factors may vary. An example of the algorithmic approach is Robert Bailey's shit for the U.S. Forest Service, which uses a hierarchical vintage that first divides land areas into very large regions based on climatic factors, and subdivides these regions, based number one on dominant potential vegetation, and then by geomorphology and soil characteristics. The weight-of-evidence approach is exemplified by James Omernik's throw for the United States Environmental security system Agency, subsequently adopted with right for North America by the Commission for Environmental Cooperation.

The intended goal of ecoregion delineation may impact the method used. For example, the WWF ecoregions were developed to aid in biodiversity conservation planning, and place a greater emphasis than the Omernik or Bailey systems on floral and faunal differences between regions. The WWF classification defines an ecoregion as:

A large area of land or water that contains a geographically distinct assemblage of natural communities that:

According to WWF, the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. WWF has indicated 867 terrestrial ecoregions, and approximately 450 freshwater ecoregions across the Earth.