Biome

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A biome, or "major life zone," is a large, geographic region of the earth's surface with distinctive plant and animal communities. There are both terrestrial biomes, such as grasslands, deserts, and tropical rain forests, and aquatic biomes, such as estuaries and lakes. A biome may also be defined as an extensive ecosystem(ecological unit of living organisms and their biotic environment)spread over a wide geographic area, or as a grouping of many ecosystems that share simimilar environmental features and communities (organisms living together in a certain area). Each biome also consists of numerous habitats (the place where a particular species lives and grows. Collectively, biomes comprise the biosphere, which is the thin area of the earth's surface where all organisms live.

Throughout recorded history, biomes have been impacted by human activity. Some of these impacts, such as deforestation, have caused serious environmental problems. It is important that humans understand and manage their local, regional, and global impacts, such that future generations can enjoy the wonder of creation that was intended by God. In biblical terms, this is referred to as the "Third Blessing," the role of humans to care for all of creation, both the abiotic and biotic elements.

Biomes represent a superficial classification. Biologists are not unanimous in their classification of biomes, nor in the number of biomes. Some may classify one region as a particular biome, but others classify the same region as an ecotone (the area where one biome overlaps another) or as part of another biome. Some biologists recognize particular sub-regions as biomes, that another scientist may identify only as one biome. In some cases, the word "biome type" is utilized, whereby several biomes are combined into this biome type. For example, the coniferous forest biome type includes the coniferous forest biomes of Europe, Asia and North America.

In general, most biologiest agree on the existence of six major land biomes: tundra, taiga, temperate deciduous forest, grasslands, deserts, and tropical rain forets, and two major water biomes of ocean and fresh water. Others add such biomes as temperate rain forests, and ***** break aquatic biomes into such categories as rivers, lakes, swamps, and estuaries.

Biomes are most strongly defined by global distributions of vegetation types, which are influenced by global climate, soils, disturbance, and other physical environment factors. In turn, climate and soil depend partly on latitude, altitude and terrain factors. A biome is composed of the climax vegetation and all associated subclimax, or degraded, vegetation, fauna and soils, but can often be identified by the climax vegetation type.


Classification of biomes

Importance of biomes

Scientists have long noted that regions of the earth with similar climate tend to have similar plants and animals. For example, the tops of mountatins are cold and ten to have siilar vegetation types as those found in polar regions. And regions with long, dry period with little rainfall are populated by animals adapted to these dry conditions. Such plasnt may flower and see during the rare priods of rainfall.

Use ful concept....


crude way of classifying ecosystems. Thie lack precison and many parts do not fit compforably.


A fundamental classification of biomes is into:

  1. Terrestrial (or continental) biomes and
  2. Aquatic 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 veld in southern Africa, prairie in North America, pampa in South America and outback in Australia.


With the excepton of deserts, each terrestrial biome is named for the dominent type of vegetation (climax vegetation, such as deciuous forest adn coniferous forests. 


Latitude Classification

Latitude is a major climate-influencing factor determining biomes. There is a good correlation between the distribution of climates with latitude, and homogenous vegetation bands. Another major factor is humidity. This can be illustrated by the fact that biodiversity increases away from the poles towards the equator, and increases with humidity.

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

Arctic or Subarctic area

Subarctic and Boreal area

  • humid type: taiga or boreal forest

Temperate cold

  • humid type : Temperate broadleaf and mixed forests, Temperate coniferous forests

Temperate warm or sub-tropical

  • humid: subtropical moist broadleaf forest
  • semi-humid: Subtropical dry broadleaf forests, Subtropical coniferous forests
  • semi-arid: Mediterranean forests, woodlands, and shrub, Temperate grasslands, savannas, and shrublands
  • Arid: Temperate deserts and xeric shrublands

Tropical

  • humid area: tropical moist broadleaf forest (tropical rainforest)
  • semi-humid area: tropical dry broadleaf forest, tropical coniferous forest
  • Semi-arid area: tropical grasslands, savannas, and shrublands
  • Arid area: deserts and xeric shrublands

Aquatic

Altitude and Latitude Classification

Another system of classification takes into account altitude and humidity, ignoring temperature as a factor. This classification is used to define the Global 200 list of ecoregions identified by the World Wildlife Fund (WWF) as priorities for conservation.

This classification gives the following terrestrial biomes :

  • Tundra (arctic, humid)
  • Boreal forests/taiga (subarctic, humid)
  • Temperate coniferous forests (temperate cold, 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)
  • Deserts and xeric shrublands (temperate to tropical, arid)
  • Mangrove (subtropical and tropical, salt and brackish water inundated)
  • Flooded grasslands and savannas (temperate to tropical, fresh water inundated)
  • Montane grasslands and shrublands (temperate to tropical, high altitude)

Imperfect Classification

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

  • Ecoregion
  • Ecotope
  • Ecozone
  • Habitat


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