Biome

The Earth's biomes comprise the biosphere and are described by the study of ecology. The concept of the biome embraces the idea of community, of interaction among plant and animal populations, and soil. A biome (which is also called a biotic area) may be defined as a major region of distinctive plant and animal communities well adapted to the physical environment of its distribution area.

Major biomes can be defined thanks to the global distribution pattern. It is frequent that local names are given to a biome when related to a specific continent. For example, temperate grassland biome is locally known as steppe, pampa or veld depending on the continent.
It is also defined by regional climate, in particular temperature and precipitations.
Other aspects are soil characteristics, as well as other physical parameters which might influence the quality of the environment : it might be related to substrate condition (due to periodic flooding for example) or altitude.
The biome is naturally defined by the type of vegetation found, vertical stratification, vegetation adaptation, or fauna.

Latitude zonation

Water and temperature are the two ecological factors which make it possible to define the climates. Those latter present a latitude distribution. It was noted a good coincidence existed between this distribution and homogeneous vegetation bands, which were called biomes.

This planetary distribution of large biomes might appear to be a simplification, but it covers an obvious climatic reality. Many people realise that biodiversity is getting higher from the poles towards the equator, be about about plant species or also with associated animal species.

Several biomes classifications may be found. Along the most common one, plants and animals extent patterns are strongly related to geography (latitude) and climate. Biomes are also sometimes identified according to the climax vegetation type, but a biome is not only composed of the climax vegetation, but also of all the associated, subclimax, or degraded flora, fauna and soils.

Two types of biomes may be defined, terrestrial (also called continental) biomes and aquatic biomes.

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The most widely used definition of biomes is related to latitude (or temperature zoning) and humidity :

• arctic or subarctic area
  • humid type : Tundra
• subarctic and boreal area
  • humid type : taiga or boreal forest or Coniferous forest
• Temperate cold
  • humid type : Temperate Broadleaf Deciduous Forest
• Temperate warm or sub-tropical
  • humid area : Mediterranean Forests
  • Semi-arid area : Temperate Grasslands or Temperate Savannas
  • Arid area : Temperate Deserts[?]
• Tropical
  • humid area : Tropical forest[?] or Rainforest
  • Semi-arid area : Tropical Grasslands[?] -- Tropical Savannas
  • Arid area : Desert

Aquatic Biomes

• continental shelf[?]
• littoral[?]
• riparian
• pond
• lake
• coral reef
• pack ice[?]
• hydrothermal vents[?]

Altitude and latitude zonations

Another classification is also including two other points.
It proposes to take into account - to a certain point - altitude, as well as strong humidity access.

This classification gives the following terrestrial biomes :

• Tundra (arctic, humid)
• Boreal Forests-Taiga (subarctic, humid)
• Temperate Coniferous Forests (temperate cold, humid)
• Temperate Broadleaf and Mixed Forests (temperate, humid)
• Temperate Grasslands, Savannas and Shrublands (temperate, semi-arid)
• Mediterranean Forests, Woodlands, and Shrub (temperate warm, humid)
• Tropical and Subtropical Coniferous Forests
• Tropical and Subtropical Moist Broadleaf Forests
• Tropical and Subtropical Dry Broadleaf Forests
• Tropical and Subtropical Grasslands, Savannas, & Shrublands
• Deserts and Xeric Shrublands
• Mangrove
• Flooded Grasslands and Savannas
• Montane Grasslands and Shrublands (high altitude)

This classification is the one used to define the Global 200

See also : Ecozone -- Ecotope[?]

External link

• info on the 14 biomes (http://www.panda.org/about_wwf/where_we_work/ecoregions/global200/pages/terra.htm)