Biome
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A biome is a climate and geographical 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 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, prairie in North America, 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:
- latitude: Arctic, boreal, temperate, subtropical, tropical.
- humidity: humid, semi-humid, semi-arid, and arid.
- seasonal variation: rainfall may be distributed evenly throughout the year, or be marked by seasonal variations.
- 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.
Contents |
[edit] Map of Biomes
| Ice desert Tundra Taiga Temperate broadleaf Temperate steppe Subtropical rainforest | Mediterranean Monsoon forest Desert Xeric shrubland Dry steppe Semidesert | Grass savanna Tree savanna Subtropical dry forest Tropical rainforest Alpine tundra Montane forests |
[edit] 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 temperatures, and subtropical, marine and continental, lowland and mountain).
- 100 Polar Domain
- 120 Tundra Division
- M120 Tundra Division - Mountain Provinces
- 130 Subarctic Division
- M130 Subarctic Division - Mountain Provinces
- 200 Humid Temperate Domain
- 210 Warm Continental Division
- M210 Warm Continental Division - Mountain Provinces
- 220 Hot Continental Division
- M220 Hot Continental Division - Mountain Provinces
- 230 Subtropical Division
- M230 Subtropical Division - Mountain Provinces
- 240 Marine Division
- M240 Marine Division - Mountain Provinces
- 250 Prairie Division
- 260 Mediterranean Division
- M260 Mediterranean Division - Mountain Provinces
- 300 Dry Domain
- 310 Tropical/Subtropical Steppe Division
- M310 Tropical/Subtropical Steppe Division - Mountain Provinces
[edit] 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)
[edit] Freshwater biomes
WWF has several systems for classifying freshwater biomes, which vary somewhat:
[edit] Global 200 freshwater major habitat types
- Large rivers
- Large river headwaters
- Large river deltas
- Small rivers
- Large lakes
- Small lakes
- Xeric basins
[edit] Freshwater major habitat types of Latin America and the Caribbean
- Large Rivers
- Large River Deltas
- Montane Rivers and Streams
- Wet-Region Rivers and Streams
- Xeric-Region Rivers and Streams
- Xeric-Region Endorheic (closed) Basins
- Flooded Grasslands and Savannas
- Cold Streams, Bogs, Swamps, and Mires
- Large Lakes
[edit] Freshwater major habitat types of Africa and Madagascar
- Closed basins and small lakes
- Floodplains, swamps, and lakes
- Moist forest rivers
- Mediterranean systems
- Highland and mountain systems
- Island rivers and lakes
- Large lakes
- Large river deltas
- Large river rapids
- Savanna-dry forest rivers
- Subterranean and spring systems
- Xeric systems
[edit] Marine biomes
[edit] Global 200 marine major habitat types
- Polar
- Temperate shelves and seas
- Temperate upwelling
- Tropical upwelling
- Tropical coral
[edit] Other marine habitat types
- Continental shelf
- littoral/Intertidal zone
- Coral reef
- Kelp forest
- Pack ice
- Hydrothermal vents
- Cold seeps
- Benthic zone
- Pelagic zone
- Neritic zone
[edit] Anthropogenic biomes
Humans 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.
[edit] Major Anthropogenic Biomes
- Dense Settlements
- Villages
- Croplands
- Rangelands
- Forested
[edit] 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.
[edit] See also
- Biomics
- Climate classification
- Ecoregion
- Ecotope
- Ecozone
- Habitat
- Biosphere reserve
- World Network of Biosphere Reserves
- Gene pool
- Genetic Pollution
- Genetic Erosion
[edit] References
[edit] 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
- Biomes at Encyclopedia of Earth
- Anthropogenic Biomes
| Ecozones |
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| Afrotropic · Antarctic · Australasia · Indomalaya · Nearctic · Neotropic · Oceania · Palearctic |
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