Page 83 - Viva ICSE Science 5 : E-book

Natural factors cause imbalance for short period. Nature regains its balance when
situations improve. But it is diffi cult to reverse long-term changes which are introduced
by human activity.

Man-made causes

Many activities of human beings cause imbalance in nature. Some man-made causes
are discussed here.

Cutting of trees: Trees are cut down on large-scale for many
products to be made out of wood. For example, sandalwood

trees are cut down in mass scale in the forests of South India.
Teak wood are much in demand for furnitures.

Many forests have been cleared for agriculture, and building

houses and factories. Human beings also cause forest fi res
to clear land for their use. Many types of trees get wiped out by forest fi re and cutting
of trees. Animals lose their habitat and cannot survive. They also get killed by forest fi re.

Loss of trees also lead to increase in the amount of carbon dioxide in the air. There is
decrease in rainfall and increase in temperature. Disturbing the producer disturbs the
interdependence and balance of nature.

Increasing number of industries and vehicles: Forest are

cleared to build industries. Harmful gases released from the
industries pollute air. In the absence of trees, air does not get
purifi ed. Industries release harmful chemicals and waste in

water bodies. These pollute water, kill marine animals and
also harms human health.

Increasing number of vehicles on streets also release

harmful gases and smoke, and contribute to air pollution.
Large number of vehicles on the roads also create noise

pollution.

Hunting: Human beings have been capturing and killing
animals for food, sports and greed for money. Many animals
are hunted in large-scale for their body parts. For example, rhinoceros are killed for their

horns, elephants are killed for their tusks, tiger, and many animals for their skin, paws
and other body parts. Because of hunting, number of these animals have decreased

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