An ecoregion (ecological
region), sometimes called a bioregion, is an ecologically and geographically defined area
that is smaller than an ecozone and larger than an ecosystem.
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 encounter of different species and communities at any given
point remain relatively constant, within an acceptable range of variation
(largely undefined at this point).
Three caveats are
appropriate for all biogeographic mapping approaches:
- Firstly, no single biogeographic framework is optimal for
all taxa. Ecoregions reflect the best compromise for as many taxa as
possible.
- Secondly, ecoregion boundaries rarely form abrupt
edges; rather, ecotones and mosaic habitats bound them.
- Thirdly, most ecoregions contain habitats that differ
from their assigned biome.
Ecoregions defined
Biodiversity is not spread evenly
across the Earth but follows complex patterns determined by climate, geology
and the evolutionary history of the planet. These patterns are called
"ecoregions". WWF defines an ecoregion as a "large unit of land or water containing a geographically distinct
assemblage of species, natural communities, and environmental conditions".
The boundaries of an ecoregion are not
fixed and sharp, but rather encompass an area within which important ecological
and evolutionary processes most strongly interact. The Global ecoregions
recognize the fact that, whilst tropical forests and coral reefs harbour the
most biodiversity and are the traditional targets of conservation
organizations, unique manifestations of nature are found in temperate and
boreal regions, in deserts and mountain chains, which occur nowhere else on
Earth and which risk being lost forever if they are not conserved.
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