LIFE ZONES, MAJOR BIOMES & MAJOR VEGETATION
The
relationship between mean annual temperature and the distribution of flora and
fauna recognized that similar zones or belts of vegetation occurred with both
increasing latitude and increasing elevation, these belts are called as Life
Zones.
Biomes are the major regional groupings
of plants and animals discernible at a global scale. Their distribution
patterns are strongly correlated with regional climate patterns and identified
according to the climax vegetation type. However, a biome is composed not only of the climax vegetation, but also of
associated successional communities, persistent subclimax communities, fauna,
and soils. The
world contains many biomes
Arctic Tundra
The Arctic tundra is a cold, vast,
treeless area of low, swampy plains in the far north around the Arctic Ocean.
It includes the northern lands of Europe (Lapland and Scandinavia), Asia
(Siberia), and North America (Alaska and Canada), as well as most of Greenland.
Another type of tundra is the alpine tundra, which is a biome that exists at
the tops of high mountains. This is the earth's coldest biome.
Coniferous
Forest
The coniferous forest biome is south of
the Arctic tundra. It stretches from Alaska straight across North America to
the Atlantic Ocean and across Eurasia. The largest stretch of coniferous forest
in the world, circling the earth in the Northern Hemisphere, is called the
“taiga.” It supplies the bulk of the world's commercial softwood timber, which
is used to make paper. These forests consist mainly of cone-bearing trees such
as spruce, hemlock, and fir, which are well suited to the cold climate
Deciduous Forest
This biome is in the mild temperate zone
of the Northern Hemisphere. Major regions are found in eastern North America,
Europe, and eastern Asia. Deciduous trees lose their leaves in fall. The
natural decaying of the fallen leaves enriches the soil and supports all kinds
of plant and animal life
Desert
A desert is an area where little or no
life exists because of a lack of water. Scientists estimate that about
one-fifth of the earth's land surface is desert. Deserts can be found on every
continent except Europe. There are two different kinds: hot and dry (such as
the Arabian and Sahara deserts) and cold and dry (such as Antarctica and the Gobi
desert). The lack of water and intense heat or cold make this biome
inhospitable to most life forms. Most of the plants in the desert are species
of cactus.
Grasslands
Grasslands are places with hot, dry
climates that are perfect for growing food. They are known throughout the world
by different names such as prairies, veld, savannas,
steppes, pampas etc.
Mountains
Mountains exist on all the continents of
the earth. Many of the world's mountains lie in two great belts. The
Circum-Pacific chain, often called the Ring of Fire. The other major belt, called the
Alpine-Himalayan, or Tethyan, system. Mountains are usually found in groups
called chains or ranges, although some stand alone. A mountain biome is very
cold and windy. The higher the mountain, the colder and windier the
environment. There is also less oxygen at high elevations
Rainforests
Tropical rainforests are found in Asia,
Africa, South America, Central America, and on many of the Pacific islands.
There are other types of rainforests around the world, too. Tropical
rainforests receive at least 70 inches of rain each year and have more species
of plants and animals than any other biome.
Many of the plants used in medicine can only be found in tropical
rainforests. The combination of heat and moisture makes this biome the perfect
environment for more than 15 million plants and animals. The thick vegetation
absorbs moisture, which then evaporates and completes the cycle by falling
again as rain. A rainforest grows in three levels. The canopy, or tallest
level, has trees between 100 and 200 feet tall. They block most of the sunlight
from the levels below. The second level, or understory, contains a mix of small
trees, vines, and palms as well as shrubs and ferns. The third and lowest level
is the forest floor, where herbs, mosses, and fungi grow.
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