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Global 200
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Global 200

The Global 200 is the list of ecoregions identified by the World Wildlife Fund (WWF) as priorities for conservation.

The Global 200 is based on the WWF's comprehensive system of ecoregions. The WWF defines an ecoregion as a "relatively large unit of land or water containing a characteristic set of natural communities that share a large majority of their species, dynamics, and environmental conditions" (Dinerstein et al. 1995, TNC 1997). The WWF has identified 867 terrestrial ecoregions, which cover the earth's land surface, as well as freshwater and marine ecoregions. The goal of this classification system is to ensure that the full range of ecosystems will be represented in regional conservation and development strategies. Of these ecoregions, the WWF selected the Global 200 as the ecoregions most crucial to the conservation of global biodiversity. The Global 200 are actually 233 ecoregions, which include 136 terrestrial, 36 freshwater, and 61 marine ecoregions.

Conservationists interested in preserving biodiversity have generally focused on the preservation of tropical rain forests because they harbor an estimated 50 percent of Earth's species. The WWF determined that a more comprehensive strategy for conserving global biodiversity should also consider the other 50 percent of species, as well as the ecosystems that support them. Several habitats, such as Mediterranean-climate shrublands, were determined to be more threatened than the tropical rain forests, and also require concerted conservation action. WWF maintains that "although conservation action typically takes place at the country level, patterns of biodiversity and ecological processes (e.g., migration) do not conform to political boundaries", which is why ecoregion-based conservation strategies are deemed essential.

Historically zoologists and botanists have developed various classification systems that take into account the world's plant and animal communties. Two of the worldwide classification systems most commonly used today were summarized by Miklos Udvardy in 1975. The biogeographical realms divide the Earth's land surface into eight realms (formerly called kingdoms, and which the WWF calls ecozones) that represent the major terrestrial communities of animals and plants, and are a synthesis of previous systems of floristic provinces and faunal regions. The biome system classifies the world into ecosystem types (i.e. forests, grasslands, etc) based on climate and vegetation. Each biogeographical realm contains multiple biomes, and biomes occur across several biogeographical realms. A system of biogeographical provinces was developed to identify specific geographic areas in each biogeographical realm that were of a consistent biome type, and shared distinct plant and animal communities. The WWF system represents a further refinement of the system of biomes (which the WWF calls major habitat types), biogeographical realms (WWF's ecozones), and biogeographical provinces (The WWF scheme divides most biogeographical provinces into multiple smaller ecoregions).

The WWF assigns a conservation status to each ecoregion in the Global 200: critical or endangered; vulnerable; and relatively stable or intact. Over half of the ecoregions in the Global 200 are rated endangered.

Based on a comprehensive list of ecoregions, The Global 200 includes all major habitat types (biomes), all ecosystems types, and species from every major habitat type. It focuses on each major habitat type of every continent (such as tropical forest or coral reefs). It uses ecoregions as the unit of scale for comparison. WWF say ecoregions could be considered as conservation units at regional scale because they meet similar biological communities.

Some ecoregions were selected over other ecoregions of the same major habitat type (biome) or ecozone. Selection of the Global 200 relied on extensive studies of 19 terrestrial, freshwater, and marine major habitat types. Selection of the ecoregions was based on analyses of species richness, species endemism, unique higher taxa, unusual ecological or evolutionary phenomena, and global rarity of major habitat type.

Global 200 ecoregion list is most helpful to conservation efforts at a regional scale: local deforestation, destruction of swamp habitats, degradation of soils, etc. However, certain phenomena, such as bird or whale migration, depend on more complex parameters not used to define the current database, such as atmospheric currents, dynamic pelagic ecosystems, etc. These would require gathering more information, and coordination of efforts between multiple ecoregions. However, the Global 200 ecoregions can help these efforts by identifying habitat sites and resting sites for migratory animals. It may also help identify the origin of invasive species, and offer insights for slowing down or stopping their intrusion.

See also: ecozone - Bioregionalism - List of the Global 200 - ecoregion conservation status

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