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A biome is a major class 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 other factors like 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:
# Terrestrial (land) biomes and
# Aquatic (water) biomes.
Biomes are often given local names. For example, a Temperate grassland or shrubland biome is known commonly as ''steppe'' in central Asia, ''savanna'' or veldt in southern Africa, ''prairie'' in North America, ''pampa'' in South America and ''outback'' or ''scrub'' in Australia.
Sometimes an entire biome may be targeted for protection, especially under an individual nation's Biodiversity Action Plan.

Contents

Terrestrial biomes

Udvardy system

Bailey system

WWF system

Aquatic biomes

Other biomes

See also

References

External links

Terrestrial biomes

Climate is a major factor determining the distribution of terrestrial biomes. Among the important climatic factors are:

★ latitude: arctic, boreal, temperate, subtropical, tropical.

★ humidity: humid, semi-humid, semi-arid, and arid.

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★ seasonal variation: rainfall may be distributed evenly throughout the year, or be marked by seasonal variations.

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★ dry summer, wet winter: most regions of the earth receive most of their rainfall during the summer months; Mediterranean climate regions receive their rainfall during the winter months.

★ elevation: increasing elevation causes a distribution of habitat types similar to that of increasing latitude.
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.

Udvardy system

In 1975, Miklos Udvardy published a system of biogeographic provinces that were divided into 12 terrestrial biomes:

★ Tropical humid forests

★ Subtropical and temperate rainforests or woodlands

★ Temperate broad-leaf forests or woodlands and subpolar deciduous thickets

★ Temperate needle-leaf forests or woodlands

★ Evergreen sclerophyllous forests, scrub, or woodlands

★ Tropical dry or deciduous forests (including Monsoon forests) or woodlands

★ Temperate grasslands

★ Warm deserts and semideserts

★ Cold-winter (continental) deserts and semideserts

★ Tundra communities and barren Arctic deserts

★ Mixed mountain and highland systems with complex zonation

★ Mixed island systems

Bailey system

Robert 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).

★ '100 Polar Domain'

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★ 120 Tundra Division

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★ M120 Tundra Division - Mountain Provinces

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★ 130 Subarctic Division

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★ M130 Subarctic Division - Mountain Provinces

★ '200 Humid Temperate Domain'

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★ 210 Warm Continental Division

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★ M210 Warm Continental Division - Mountain Provinces

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★ 220 Hot Continental Division

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★ M220 Hot Continental Division - Mountain Provinces

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★ 230 Subtropical Division

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★ M230 Subtropical Division - Mountain Provinces

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★ 240 Marine Division

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★ M240 Marine Division - Mountain Provinces

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★ 250 Prairie Division

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★ 260 Mediterranean Division

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★ M260 Mediterranean Division - Mountain Provinces

★ '300 Dry Domain'

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★ 310 Tropical/Subtropical Steppe Division

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★ M310 Tropical/Subtropical Steppe Division - Mountain Provinces

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★ 320 Tropical/Subtropical Desert Division

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★ 330 Temperate Steppe Division

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★ M330 Temperate Steppe Division - Mountain Provinces

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★ 340 Temperate Desert Division

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★ M340 Temperate Desert Division - Mountain Provinces

★ '400 Humid Tropical Domain'

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★ 410 Savanna Division

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★ M410 Savanna Division - Mountain Provinces

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★ 420 Rainforest Division

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★ M420 Rainforest Division - Mountain Provinces

WWF system

A team of biologists convened by the World Wildlife Fund (WWF) developed an ecological land classification system that identified 14 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:

★ Tundra (arctic)

★ Boreal forests/taiga (subarctic, humid)

★ Temperate coniferous forests (temperate, humid to semi-humid)

★ Temperate broadleaf and mixed forests (temperate, humid)

★ Temperate grasslands, savannas, and shrublands (temperate, semi-arid)

★ Mediterranean forests, woodlands, and shrub (temperate warm, semi-humid to semi-arid with winter rainfall)

★ Tropical and subtropical coniferous forests (tropical and subtropical, semi-humid)

★ Tropical and subtropical moist broadleaf forests (tropical and subtropical, humid)

★ Tropical and subtropical dry broadleaf forests (tropical and subtropical, semi-humid)

★ Tropical and subtropical grasslands, savannas, and shrublands (tropical and subtropical, semi-arid)

★ Montane grasslands and shrublands (alpine or montane climate)

★ Deserts and xeric shrublands (temperate to tropical, arid)

★ Mangrove (subtropical and tropical, salt water inundated)

★ Flooded grasslands and savannas (temperate to tropical, fresh or brackish water inundated)

Aquatic biomes

★ Continental shelf

★ littoral/Intertidal zone

★ Riparian

★ Pond

★ Coral reef

★ Kelp forest

★ Pack ice

★ Hydrothermal vents

★ Cold seeps

★ Benthic zone

★ Pelagic zone

★ Neritic zone

Other biomes

The 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

★ Climate classification

★ Ecoregion

★ Ecotope

★ Ecozone

★ Habitat

★ Biosphere reserve

★ World Network of Biosphere Reserves

★ Gene pool

★ Genetic Pollution

★ Genetic Erosion

References

1. Biomes Encyclopedia of Earth

External links

★ Bailey's Description of the Ecoregions of the United States

★ Biomes of the world (Missouri Botanic Garden)

★ Biomes Quiz

★ Global Currents and Terrestrial Biomes Map