Biome
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A biome is a climatically and geographically defined area of ecologically similar communities of plants, animals, and soil organisms, often referred to as ecosystems. Biomes are defined based on factors such as plant structures (such as trees, shrubs, and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland, savanna), and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic, or historical similarities. Biomes are often identified with particular patterns of ecological succession and climax vegetation. The biodiversity characteristic of each biome, especially the diversity of fauna and subdominant plant forms, is a function of abiotic factors and the biomass productivity of the dominant vegetation. Species diversity tends to be higher in terrestrial biomes with higher net primary productivity, moisture availability, and temperature.[1] Ecoregions are grouped into both biomes and ecozones. A fundamental classification of biomes is into:
Biomes are often given local names. For example, a Temperate grassland or shrubland biome is known commonly as steppe in central Asia, prairie in North America, and pampas in South America. Tropical grasslands are known as savanna or veldt in southern Africa and outback or scrub in Australia. Sometimes an entire biome may be targeted for protection, especially under an individual nation's Biodiversity Action Plan. Climate is a major factor determining the distribution of terrestrial biomes. Among the important climatic factors are:
Biodiversity generally increases away from the poles towards the equator and increases with humidity. The most widely used systems of classifying biomes correspond to latitude (or temperature zoning) and humidity.
Map of BiomesImage:Vegetation-no-legend.PNG
Terrestrial biomes classified by vegetation
Bailey systemRobert G. Bailey developed a biogeographical classification system for the United States in a map published in 1975. Bailey subsequently expanded the system to include the rest of North America in 1981 and the world in 1989. The Bailey system is based on climate and is divided into four domains (Polar, Humid Temperate, Dry, and Humid Tropical), with further divisions based on other climate characteristics (subarctic, warm temperate, hot temperate, and subtropical; marine and continental; lowland and mountain).
WWF systemA team of biologists convened by the World Wildlife Fund (WWF) developed an ecological land classification system that identified fourteen biomes, called major habitat types, and further divided the world's land area into 825 terrestrial ecoregions. This classification is used to define the Global 200 list of ecoregions identified by the WWF as priorities for conservation. The WWF major habitat types are as follows:
Freshwater biomesWWF has several systems for classifying freshwater biomes, which vary somewhat: Global 200 freshwater major habitat types
Freshwater major habitat types of Africa and Madagascar
Marine biomesGlobal 200 marine major habitat types
Other marine habitat types
Anthropogenic biomesHumans have fundamentally altered global patterns of biodiversity and ecosystem processes. As a result, vegetation forms predicted by conventional biome systems are rarely observed across most of Earth's land surface. Anthropogenic biomes provide an alternative view of the terrestrial biosphere based on global patterns of sustained direct human interaction with ecosystems, including agriculture, human settlements, urbanization, forestry and other uses of land. Anthropogenic biomes offer a new way forward in ecology and conservation by recognizing the irreversible coupling of human and ecological systems at global scales and moving us toward an understanding how best to live in and manage our biosphere and the anthropogenic biosphere we live in. Major Anthropogenic Biomes
Other biomesThe Endolithic biome, consisting entirely of microscopic life in rock pores and cracks, kilometers beneath the surface, has only recently been discovered and does not fit well into most classification schemes. See also
References
External links
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