Biome
From Wikipedia, the free encyclopedia.
A biome is not a geographic place so much as it is a major regional group of distinctive
plants and animals, discernible at a global scale.
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.
Contents [hide]
1 Latitude zonation
1.1 Arctic or Subarctic area
1.2 Subarctic and Boreal area
1.3 Temperate cold
1.4 Temperate warm or sub-tropical
1.5 Tropical
1.6 Aquatic
2 Altitude and latitude zonations
3 External Links
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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.
The most widely used definition of biomes is related to latitude (or temperature zoning)
and humidity :
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Arctic or Subarctic area
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humid type : Tundra
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Subarctic and Boreal area
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humid type: taiga or boreal forest
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Temperate cold
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humid type : Temperate broadleaf and mixed forests, Temperate coniferous
forests
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Temperate warm or sub-tropical
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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
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Tropical
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humid area : Tropical forest or Rainforest
Semi-arid area : Tropical Grasslands -- Tropical Savannas
Arid area : Desert
[edit]
Aquatic
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continental shelf
littoral
riparian
pond
lake
coral reef
pack ice
hydrothermal vents
cold seeps
benthic zone
pelagic zone
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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 :
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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, and shrublands
Deserts and xeric shrublands
Mangrove
Flooded grasslands and savannas
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Montane grasslands and shrublands (high altitude)
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.
Tundra
From Wikipedia, the free encyclopedia.
In physical geography, tundra is an area where tree growth is hindered by low
temperatures and short growing seasons. The term tundra comes from the Finnish word
tunturia, which means treeless plain.
There are three types of tundra: arctic tundra, antarctic tundra, and alpine tundra. In
all of these types, the dominant vegetation is grasses, mosses, and lichens. Trees do not
grow in the tundra. The ecotone (or ecological boundary region) between the tundra and
the forest is known as the tree-line or timberline.
See also:
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Fellfields
Desert - tree growth hindered by low rainfall
Heath, Pasture - tree growth hindered by human activity, not climate
Alpine climate
Contents [hide]
1 Arctic tundra
2 Antarctic tundra
3 Alpine tundra
4 Tundra ecoregions
5 External link
[edit]
Arctic tundra
Arctic tundra occurs in the far Northern hemisphere, north of the taiga belt. Arctic tundra
includes vast areas of northern Russia and Canada. The subsoil of arctic tundra is
permafrost, which contains permanently frozen water. The arctic tundra is home to
several peoples who are mostly nomadic reindeer herders, among them are the Sami.
Notable animals in the arctic tundra include:
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Caribou or Reindeer
Musk ox
Polar bear
Lemmings
Due to the harsh climate of the arctic tundra, regions of this kind have seen little
exploitation even though they are sometimes rich in natural resources such as oil and
uranium. In recent time this has begun to change, and in Alaska, Russia and some other
parts of the world the tundra is being ever more subjected to human interference.
[edit]
Antarctic tundra
Antarctic tundra occurs on Antarctica and on several antarctic and subantarctic islands,
including South Georgia and the South Sandwich Islands and the Kerguelen Islands.
Antarctica is mostly too cold and dry to support vegetation, and most of the continent is
covered by ice fields. However, some portions of the continent, particularly the Antarctic
Peninsula, have areas of rocky soil that support tundra. Its flora presently consists of
around 250 lichens, 100 mosses, 25-30 liverworts, around 700 terrestrial and aquatic
algal species, which live on the areas of exposed rock and soil around the shore of the
continent. Antarctica's two flowering plant species, the Antarctic hair grass
(Deschampsia antarctica) and Antarctic pearlwort (Colobanthus quitensis), are found on
the northern and western parts of the Antarctic Peninsula.
In contrast with the arctic tundra, the antarctic tundra lacks a large mammal fauna, mostly
due to its physical isolation from the other continents. Sea mammals and sea birds,
including seals, penguins, inhabit areas near the shore, and some small mammals, like
rabbits and cats, have been introduced by humans to some of the subantarctic islands.
The flora and fauna of Antarctica and the Antarctic Islands (south of 60º south latitude)
are protected by the Antarctic Treaty.
[edit]
Alpine tundra
Typical alpine tundra
Alpine tundra occurs at high enough altitude at any latitude on Earth. Alpine tundra also
lacks trees, but does not usually have permafrost, and alpine soils are generally better
drained than permafrost soils. Alpine tundra transitions to subalpine forests or Montane
grasslands and shrublands below the tree-line; stunted forests occurring at the foresttundra ecotone are known as Krummholz.
Notable animals in the alpine tundra include:
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Kea parrot
Marmot
Mountain goat
Pika
The following map features the five major biomes and their most important subcategories. The map was based on data compiled from Physical Geography of the
Global Environment, 2nd Edition, by H. J. De Blij, et al; Paperback.
Tundra Biomes
A. Locations
Tundras are characteristic of Arctic or Alpine regions where the severity of
environmental conditions excludes tree growth. 30 days of 10°C ave.
temperature and 8 mos cold season.
Arctic tundra occurs north of the boreal forest or taiga and thus form a treeless
ring south of the zone of permanent ice (North America, Greenland, Eurasia).
In the Antarctica, tundra area is very small because of the lack of large
continental masses. Develops only on certain small Antarctic islands such as
South George and MacQuarie Island on several spots on the most northerly
extension of Antarctica proper (only 2 flowering plants! Deschampsia
antarctica [Poaceae] and Colobanthus quitensis [Caryophyllaceae cushion
plant].
Alpine regions include Rocky Mountains, European Alps, Himalayas, and
Austral-antarctic area (South Island, also Tasmania, Snowy Mts. in Australia).
Exclude tropical 'puna' in Andes and similar high elevation peaks in East
Africa (will deal with later). Links of Austral-antarctic region with puna
(Azorella, Umbelliferae).