Page 171 - SST Class 06

plants and animals that survive naturally in a the ground. The tress are very tall. Four or five
specific region and are part of the biosphere. The layers of canopy of trees are easily visible.
biosphere is the narrow zone where the litho- Tropical Deciduous Forests : Tropical decidu-
sphere, the hydrosphere and the atmosphere ous forests are also called the Monsoon forests.
interact with each other. Long dry season of summer leads these forests to

An ecosystem refers to the natural surroundings shed their leaves in order to prevent evaporation.
in which living beings and non-living beings Period of shedding the leaves varies from each
support each other. Wild life includes animals, species of trees. Hence, all the trees do not shed
birds and insects and aquatic animals. All birds leaves at one and the same time.
and animals, regardless of their size, contribute in
different ways to maintain the balance in an
ecosystem.
The natural vegetation in an area depends on the
temperature and the moisture available. The
main types of natural vegetation found over the
world are— Forests, Grasslands, Scrubs and
Tundra. The growth of vegetation in forests
varies from region to region. Forests can be
classified into evergreen or deciduous, depending
on when the trees shed their leaves.
Tropical Deciduous Forests
Tropical Rain Forests : These forests are
Tropical deciduous forests are grown in the areas
found in areas where rainfall is above 200
with annual rainfall of 70-200 cm. Sandal wood,
centimeters. The vegetation consists of evergreen
Shisam, Mahua, Sal, Teak and Bamboo are
and semi-evergreen trees. This vegetation type is
important species of trees. They are famous for
fond on the western slopes of Western Ghats,
their economic importance. They supply timber
wetter parts of Assam and Meghalaya, parts of
for use in various activities.
West Bengal, Orissa and Andaman and Nicobar
Islands. The common varieties of Trees include These forests are most commonly found in the
Jamun, rosewood, ebony and mahogany. These Chhotanagpur plateau covering Chhattisgarh
forests are very dense. Very little light penetrates and some parts of Madhya Pradesh, western
parts of Odisha and Jharkhand. In the
Himalayan region, they are found in the
Shiwalik. The most common varieties of trees
include teak, sal, sandalwood, mahogany, sisam
and bamboos. These forests are also known as
monsoon forests and are rapidly being cleared
for cultivation of crops.

Thorn Forests : They are found in areas receiv-
ing less than 75 cm rainfall. These areas include
north-western parts of the country in Rajasthan,
Gujarat, Punjab and Haryana. They also occur
Tropical Rain Forests

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