jueves, 16 de diciembre de 2010

The boreal forest or taiga

Boreal forests and northern forests (boreas in greek for north) or also called Taiga is a biome or biotic area, a certain part of the planet that shares climate, vegetation and fauna, that develop south of the tundra (the tundra is a biome characterized by subsurface ice and lack of woody vegetation, mainly by extending the northern hemisphere: in Siberia, Alaska, northern Canada, southern Greenland and the Arctic coast of Europe), forming these boreal forests, an almost continuous belt of coniferous forests that extend across the interior of the sub arctic regions of Eurasia and North America. Boreal forests are the northernmost forests of the planet (most ranging between 50 and 60 degrees north latitude). This biome occurs only in the Northern Hemisphere, Southern Hemisphere because in these latitudes there are no masses. Yet it is one of the largest biomes on Earth. It stretches from Alaska and Canada in the North American continent and in Scandinavia and northern Russia (Siberia) in Eurasia. And it is the boreal forest along the tundra, one of the major biomes of the cold climates of the Earth.
These boreal forests are made up mostly of conifers (spruce, fir, pine, larch) and for most of the year are covered with snow. Its appearance is usually very homogeneous, since they are dominated by few species with a similar appearance: straight trunks and tree taper, with small leaves and narrow (acicular).
With these environmental conditions of severe weather, frozen ground most of the year and nutrient-poor soils, are conifers that dominate the vegetation. This type of trees (whose seeds are enclosed in cones or pineapples) were more widespread in earlier geological epochs, while at present, are angiosperms (flowering plants true), more developed and diversified, which dominate most terrestrial biomes. Conifers, today is just as dominant in the boreal forest and mountainous areas in temperate regions, forming the boundaries of both latitudinal and altitudinal tree line.
The growth form of boreal coniferous forests is mainly determined by its characteristic conical shape, which favours the fall of snow on the branches and prevents breakage, and its needle-like leaves (hence also known as aciculifolios forests). This type of narrow leaves and thick, waxy cuticle impermeable to water, allows them to withstand frosts and drought, they present a very small surface transpiration. Although these are boreal wet winter soil water is frozen and the trees can not absorb (winter drought) and replace what is lost by evaporation. Other trees prevent this water loss by dropping their leaves in winter, but the conifers are mostly evergreen. The permanence of the leaves in winter (evergreen or evergreen forests) allows them to perform photosynthesis in story temperatures rise in spring and the ground thaws, taking better advantage of short growing season.
At its northern fringe and close to the tundra growth of these forests is very slow and the trees do not reach too high (due to poor soil, the permafrost, and low temperatures). They are very closed forest under story and have a great abundance of lichens (open boreal forest or taiga true). If they are disturbed by fire, mining, or logging, recover very slowly. As we're moving toward the south, the forests are denser and taller (closed boreal forest), until in the vicinity of forests are temperate deciduous tree species enriched this typical of other biome. In addition to the deciduous forests can also limit the south by the great American prairie or Asiatic steppe.
The adaptations of the fauna in this climate so rigorous include: migration (many birds), hibernation (some mammals such as bears), winter white fur (fox, wolf, hare, owl ,..), seed storage for winter ( Certain birds, squirrels, ..) and development of winter coats with great insulation (sable, ermine...).
Protecting forests means protecting the climate Boreal
Images of giant trees in tropical regions collapsing focus the debate on forest protection. However, the forests of temperate and cold latitudes also play a role in combating climate change. Boreal forests go to one of the key regions for global climate. According to estimates by scientists who study these biomes, only between 2% and 3% of them are sufficiently protected. Boreal forests are a key region from the ecological point of view, since, due to its sensitivity to changes and their size can influence the climate.
In Canada, as in Russia and Scandinavia, boreal forests are threatened by unsustainable timber production and the progressive development of new areas.
Intact boreal forest can not only store large amounts of carbon. It is also more resistant to the effects of global warming. Just the opposite of what happens to those whose boreal forests large trees have disappeared intensive logging, and concludes an extensive study by Canadian scientists on behalf of Greenpeace. Especially problematic is the thawing of the soil layer that is permanently frozen ground called permafrost, and which grows most of these conifer forests. A land that for thousands of years was has stored greenhouse gases. When permafrost melts, facilitates the release into the atmosphere of methane gas harmful to the environment. Healthy forests are able to retain on the floor much of these gases.
Public debate: moving tropical forests worldwide attention to the boreal forest or taiga
Often forests in cold areas play a role in the discussion on forest protection worldwide. Unfortunately, was lack of knowledge in the Canadian public of the significance and sensitivity of these issues? The protection of tropical forests crowns the world stage on the issue of deforestation and its impact on climate change. (Blue Environmentalists) has proposed to develop an educational program in Canada for the protection of this important biome.

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