Diario de clase de sociales

12 octubre, 2011

Biomes, part 1

Filed under: 3º de ESO,Bilingüismo,Climatología,Geografía,Medios Naturales — rafaelcastell @ 5:11 pm

EARTH’S BIOMES

 

Biomes are climatically and geographically defined as natural areas with similar conditions on the Earth (climate, vegetation, soil, wildlife…) and are often referred to as ecosystems. Biomes are defined by factors such as vegetation and species of flora or plants (forest, woodland, savanna… and trees and shrubs as oaks, cork trees or rosemary,…), wildlife and climate.

Polar, Continental, Atlantic or oceanic, Mediterranean, Chinese, High mountain, desertic, dry or humid Tropical, Equatorial are the main kinds of climate we have studied, and each one belongs to a kind of biome or ecosystem. We are going to learn the main features of each biome and know how to distinguish them in a picture of a landscape.

The biomes we will see are: tundra, taiga or coniferous forest, deciduous or caducifolio forest, Mediterranean woodland and shrubland, desert, savanna, tropical forest and jungle or rainforest. Each biome has different and typical kinds of trees, shrubs, soil and wildlife, adapted to its unique conditions. Besides, we can study the most important threats or dangers of each biome, such as fire in the Mediterranean woodland or deforestations due to excessive logging in the rainforests or coniferous forests.

 

The tundra is located in high latitudes in the northern hemisphere, between 55º N and the Arctic Circle. Beyond this line or also in the Antarctica, we can find only an ice covered area, throughout the year. South of the Tundra, is the Taiga or Coniferous Forest. In the Tundra summers are short and cool, about 5ºC, and winters are long and very cold, with temperatures dropping to -30ºC. Precipitation is low, usually less than 250/mm per year. The main form of precipitation is snow. Strong winds are typical of this biome all through the year.

 

There is little vegetation in the Tundra, due to the extreme cold, the lack of sun and the rocky soil. The main types of plants are lichens and moss, apart from grasses and dwarf shrubs. Most of the wildlife migrate south for the winter, as reindeers or foxes.

 

The Taiga or coniferous Forest is the world’s largest biome, and makes up 29% of the world’s forest cover. It is located mainly in Russia and Canada, above 50ºN, or in the south of Chile and Argentina in South America. Summers are short but usually above 15ºC, especially in inland areas. Winters are very cold and have long hours of darkness. Temperatures can reach as low as -25ºC. Precipitation is generally less than 500 mm yearly, in form of snow in winter. Most of the precipitation however occurs during the summer.

 

A great number of trees in the taiga are coniferous, that’s why it’s also known as Coniferous forest. These trees have needles instead of leaves to prevent moisture loss and endure cold temperatures in winter. Coniferous trees are evergreen and have a cone shape, so that snow slides off. Typical coniferous trees are firs, black pines and spruce. Some broadleaf or deciduous trees can be found also in the taiga, as birch, aspen or willow. Wildlife is very rich. Some animals, such as the grizzly bear, avoid winters by hibernation.

 

 

 

The deciduous forest areas can be found in the areas with Atlantic or oceanic climate or even with chinese climate, between 40º and 50ºN/S. Winters are mild and summers are cool, with low temperature oscillation. Precipitation is usually above 1.000 mm/year, without drought in any month.

Deciduous trees drop their leaves in autumn, like birches, maples, oaks, browns or elms. Some trees change the colour of their leaves before dropping. Soils are rich due to the fallen leaves.

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