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Biomes

Biomes are the composite of all species within a large scale ecological community. In the natural environment, these assemblies have typically co-evolved, so that they have a natural arrangement in terms of their positioning to compete for sunlight, water and nutrient resources; in some cases these associations are symbiotic, but in most cases they are simply optimal spatial arrangements to take advantage of all the resources available in a given habitat. For example, there is typically a vertical tiering, where plants of differing light requirements can occupy canopy, mid-level or forest floor niches; the same theory applies even in a grassland, where the canopy is simply the tallest of the grasses or herbs.

In the case of water competition, depth of rooting and tolerance to arid soils are chief determinants for spatial arrangement; as far as nutrient competition, plants will compete to determine the most robust competitor for a given edaphic niche. While the outcome geometry for the plant palette usually appears random, there is a complex network of ecological theory at work that determines the layout of the assembled community. The same concept applies to aquatic communities as to terrestrial systems, with some plants having immersed roots and others, either macrophytes or phytoplankton, floating or immersed at varying levels suitable for their sunlight needs.

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Recently Updated
Sierra de la Laguna dry forests Last Updated on 2014-04-23 16:56:19 Located at the southern end of the Baja California Peninsula in Mexico, the Sierra de la Laguna dry forests ecoregion was once an isolated island, containing a large number of endemic species. After sufficient mountain uplift and the joining the Baja Peninsula mainland, this ecoregion underwent significant speciation, and is thus today high in species diversity; this portion of the peninsula contains the majority of the species found in the southern part of the Baja Peninsula. The Sierra de la Laguna dry forest is a subtropical dry forest classified within the Tropical and Subtropical Broadleaf Forests biome; the ecoregion is threatened by overgrazing from domestic cattle and the hunting by humans. Designated as a Protected Natural Area (PNA), this important ecoregion is at risk from habitat... More »
Jamaican moist forests Last 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 tundra Last 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 forests Last Updated on 2014-04-22 18:33:49 The 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 »
Indus River Delta-Arabian Sea mangroves Last 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 »