DEFORESTATION AND ITS CAUSES
We saw in Class VII that Paheli and Boojho had visited the forest along with Professor Ahmad and Tibu. They were eager to share their experiences with their classmates. Other children in the class were also eager to share their experiences as some of them had visited Bharatpur Sanctuary. Some others had heard about Kaziranga National Park, Lockchao Wildlife Sanctuary, Great Nicobar Biosphere Reserve and Tiger Reserve, etc.
A great variety of plants and animals exist on earth. They are essential for the well-being and survival of mankind. Today, a major threat to the survival of these organisms is deforestation. We know that deforestation means clearing of forests and using that land for other purposes. Trees in the forest are cut for some of the purposes mentioned below:
* Procuring land for cultivation.
* Building houses and factories.
* Making furniture or using wood as fuel.
Some natural causes of deforestation are forest fires and severe droughts.
Activity 7.1:
* Add more causes of deforestation to your list and classify them into natural and man-made.
Questions
What is the purpose of making national parks, wildlife sanctuaries and biosphere reserves?
Source: This topic is taken from NCERT TEXTBOOK
CONSEQUENCES OF DEFORESTATION
Paheli and Boojho recalled the consequences of deforestation. They remembered that deforestation increases the temperature and pollution level on the earth. It increases the level of carbon dioxide in the atmosphere. Groundwater level also gets lowered. They know that deforestation disturbs the balance in nature. They were told by Professor Ahmad that if the cutting of trees continues, rainfall and the fertility of the soil will decrease. Moreover, there will be increased chances of natural calamities such as floods and droughts.
Recall that plants need carbon dioxide for photosynthesis. Fewer trees would mean that less carbon dioxide will be used up resulting in its increased amount in the atmosphere. This will lead to global warming as carbon dioxide traps the heat rays reflected by the earth. The increase in temperature on the earth disturbs the water cycle and may reduce rainfall. This could cause droughts.
Deforestation is a major cause that leads to the change in soil properties. The physical properties of the soil get affected by plantation and vegetation. Recall from Class VII how trees prevent soil erosion. Fewer trees result in more soil erosion. Removal of the top layer of the soil exposes the lower, hard, and rocky layers. This soil has less humus and is less fertile. Gradually the fertile land gets converted into deserts. It is called desertification.
Deforestation also leads to a decrease in the water holding capacity of the soil. The movement of water from the soil surface into the ground (infiltration rate) is reduced. So, there are floods. The other properties of the soil like nutrient content, texture, etc., also change because of deforestation.
We have studied in Class VII that we get many products from forests. List these products. Will we face a shortage of these products if we continue cutting trees?
Activity 7.2:
* Animal life is also affected by deforestation. How? List the points and discuss them in your class.
Questions
How does deforestation reduce rainfall on the one hand and lead to floods on the other?
Source: This topic is taken from NCERT TEXTBOOK