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.
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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.
The most widely used definition of biomes is related to latitude (or temperature zoning) and humidity :
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 :
Latitude zonation
Aquatic Biomes
Altitude and latitude zonations
This classification is the one used to define the Global 200
The Endolithic biome, consisting entirely of microscopic life that lives inside pores and cracks in rock kilometers beneath the surface, has only recently been discovered and does not fit well into most classification schemes.
See also : Ecozone -- Ecotope