Biogeography is the study of the distribution of biological organisms. The scale of analysis ranges from very small micro-topography regimes to continental dimensions. Fundamental concepts in this field of study are the nature of barrier formation and response of species to their patterns of travel and migration; in particular, the presence of rivers, mountain ranges, deserts and other natural boundaries are examples of large scale barriers. Besides such major landform barriers there are soil, topographic and meteorological factors that influence the distribution of each species. In the case of smaller scale regimes that are applicable for some bacteria or limited range plant species, there are often very restricted niches; for example, certain bacteriaextremophiles may be limited to such localized features as small geyser pools, and some rare plants may have a single extant colony defined specialized soils such as serpentine and narrow climatic zone. Inherent in the concept of biogeography are the processes of speciation, extinction, dispersal and migration.
Chile has eight ecoregions that occur entirely or partly within its borders on the mainland and three ecorgions offshore:
Jamaican moist forestsLast Updated on 2014-04-23 15:02:52
The Jamaican moist forests ecoregion is characterized by rich floral and faunal diversity. In contrast to the rest of the Caribbean archipelago, Jamaica was never connected to another landmass. As a result, the island has a particularly high proportion of endemic plant and animal species. Two notable forest areas in this ecoregion are the Blue and John Crow Mountains and Cockpit Country. Deforestation rates in this ecoregion are very high; however, due to the establishment of new protected area and management systems these rates should be slowing as logging is prohibited. Although a lack of adequate environmental legislation and enforcement seems the obvious impediments to conservation, the fundamental problem in Jamaica as in many other areas is the pervasive poverty that must be overcome.
Jamaica is the 3rd largest island of the Caribbean archipelago, is approximately 230... More »
Beringia lowland tundraLast Updated on 2014-04-22 18:58:15
The Beringia lowland tundra ecoregion is formed by three major disjunct areas along the Bering Sea coast of Alaska from the base of the Alaska Peninsula to Kotzebue Sound, as well as one smaller area on the east side of St. Lawrence Island and St. Matthew Island. The ecoregion is characterized by low, flat, or gently rolling terrain, wet soils, and resulting predominance of wet and mesic graminoid herbaceous vegetation. In better drained areas, especially in the somewhat more rolling portions of the section surrounding Bristol Bay, dwarf shrub communities occur interspersed with the wet herbaceous tundra, dominated by sedges, including Eriophorum angustoifolium and Carex spp. Dwarf shrub vegetation is usually dominated by ericaceous species, including crowberry (Empetrum nigrum). In some limited areas of favorable soil drainage and microclimate, stands of black and white... More »
Arizona Mountains forestsLast Updated on 2014-04-22 18:33:49The Arizona Mountain Forests extend from the Kaibab Plateau in northern Arizona to south of the Mogollon Plateau into portions of southwestern Mexico and eastern Arizona. This ecoregion is an element of the Temperate Coniferous Forests biome. The species richness in this ecoregion is moderate, with vertebrate taxa numbering 375 species. The topography consists chiefly of steep foothills and mountains, but includes some deeply dissected high plateaus. Elevations range from 1370 to 3000 meters (m) with some peaks as high as 3840 m. Soil types have not been well defined; however, most soils are entisols, with alfisols and inceptisols in upland areas. Stony terrain and rock outcrops occupy large areas on the mountains and foothills.
Vegetation zones in this ecoregion resemble the Rocky Mountain Life Zones but at higher elevations. Although forests in this ecoregion are too far south to... More »
Sonoran-Sinaloan transition subtropical dry forestLast Updated on 2014-04-22 16:55:19
The Sonoran-Sinaloan transition subtropical dry forest ecoregion comprises a distinct zone of dry forest that forms a north-south transition between the Sonoran Desert to the north and the Sinaloan dry forests to the south. The Sonoran-Sinaloan transition subtropical dry forest ecoregion shares elements of climate, as well as soil and topographic attributes, with both neighbouring ecoregions. The subject ecoregion also comprises part of a much broader ecological unit: the Tropical and Subtropical Dry Broadleaf Forests biome. The southeastern ecoregion boundary marks the end of the Nearctic and the beginning of the Neotropical biogeographic realm.
Nonetheless, the Sonoran-Sinaloan transition subtropical dry forest manifests an interesting mixture of temperate and tropical biota, many species of which find either their northern or southern limits here. There is a generally low... More »
Indus River Delta-Arabian Sea mangrovesLast Updated on 2014-04-22 16:43:36
The Indus River Delta-Arabian Sea mangroves ecoregion represents a mangrove habitat that is adapted to some of the most extreme temperatures and salinity conditions in the Indo-Pacific region. As a transition from the marine to freshwater and terrestrial systems, mangroves provide critical habitat for numerous species of fishes and crustaceans that are adapted to live among the tangled mass of pneumatophores, the roots that reach up from the muddy, anaerobic substrate to obrain the supply of oxygen for the mangrove trees.
This ecoregion lies at the delta of the Indus River, which originates in the Tibetan Plateau and flows through the northwestern part of India and into the arid Thar Desert in Pakistan before finally emptying into the Arabian Sea. There are high salinity levels in the sloughs because of the high evaporation rates and the salts that are washed down by the... More »
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