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ecological biome

Biomes are climatically and geographically defined as similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms,[1] and are often referred to as ecosystems. Some parts of the earth have more or less the same kind of abiotic and biotic factors spread over a large area, creating a typical ecosystem over that area. Such major ecosystems are termed as biomes. Biomes are defined by 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 (quasiequilibrium state of the local ecosystem). An ecosystem has many biotopes and a biome is a major habitat type. A major habitat type, however, is a compromise, as it has an intrinsic inhomogeneity. Some examples of habitats are ponds, trees, streams, creeks, and burrows in the sand or soil.

The biodiversity characteristic of each extinction, especially the diversity of fauna and subdominant plant forms, is a function of abiotic factors and the biomass productivity of the dominant vegetation. In terrestrial biomes, species diversity tends to correlate positively with net primary productivity, moisture availability, and temperature.[2]

Ecoregions are grouped into both biomes and ecozones.

A fundamental classification of biomes are:

  1. Terrestrial (land) biomes
  2. Aquatic biomes (including freshwater biomes and marine biomes)

Biomes are often known in English by 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 in Australia, whereas in southern Africa it is known as certain kinds of veld (from Afrikaans).

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, semihumid, semiarid, 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.

The most widely used systems of classifying biomes correspond to latitude (or temperature zoning) and humidity. Biodiversity generally increases away from the poles towards the equator and increases with humidity.


2013-3-24 22:25:25

Posted by DoctorZ | 阅读全文 | 回复(1) | 引用通告 | 编辑

Re:ecological biome

WWF system

A team of biologists convened by the World Wide Fund for Nature (WWF) developed an ecological land classification system that identified fourteen biomes,[8] called major habitat types, and further divided the world's land area into 867 terrestrial ecoregions. Each terrestrial ecoregion has a specific EcoID, format XXnnNN (XX is the ecozone, nn is the biome number, NN is the individual number). 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:

  • 01 Tropical and subtropical moist broadleaf forests (tropical and subtropical, humid)
  • 02 Tropical and subtropical dry broadleaf forests (tropical and subtropical, semihumid)
  • 03 Tropical and subtropical coniferous forests (tropical and subtropical, semihumid)
  • 04 Temperate broadleaf and mixed forests (temperate, humid)
  • 05 Temperate coniferous forests (temperate, humid to semihumid)
  • 06 Boreal forests/taiga (subarctic, humid)
  • 07 Tropical and subtropical grasslands, savannas, and shrublands (tropical and subtropical, semiarid)
  • 08 Temperate grasslands, savannas, and shrublands (temperate, semiarid)
  • 09 Flooded grasslands and savannas (temperate to tropical, fresh or brackish water inundated)
  • 10 Montane grasslands and shrublands (alpine or montane climate)
  • 11 Tundra (Arctic)
  • 12 Mediterranean forests, woodlands, and scrub or sclerophyll forests (temperate warm, semihumid to semiarid with winter rainfall)
  • 13 Deserts and xeric shrublands (temperate to tropical, arid)
  • 14 Mangrove (subtropical and tropical, salt water inundated)

2013-3-24 22:27:36

Posted by doctorzhang | 个人主页 | 引用 | 返回 | 删除 | 回复

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