- 1 Deforestation: Causes, Effects, and Preventive Measures
- 1.1 Deforestation And Its Causes
- 1.2 Consequences of Deforestation
- 1.3 (i) Deforestation will lead to a shortage of wood and other forest products
- 1.4 (ii) Deforestation will cause an increase in temperature of earth’s atmosphere leading to global warming
- 1.5 (iii) Deforestation will cause soil erosion making the soil infertile and lead to desertification
- 1.6 (iv) Deforestation will cause frequent flooding of rivers leading to loss of life and property
- 1.7 (v) Deforestation affects the water cycle leading to decrease in rainfall. The decrease in rainfall lowers the groundwater level and could cause droughts
- 1.8 (vi) Deforestation leads to the extinction of many wild animals and plants
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Deforestation: Causes, Effects, and Preventive Measures
The term ‘conservation’ means ‘the process of keeping and protecting something from damage’. So, the conservation of plants and animals means that plants and animals which occur in the forests should be kept in a way that they remain protected in the natural environment in which they are found.
Before we go further and discuss the conservation of plants and animals in detail, we should know the meanings of some new terms such as biosphere, wildlife, biodiversity, and ecosystem which will be used in this chapter.
Biosphere is that part of the earth in which living organisms exist (or which supports life). Biosphere includes land surface of the earth, atmosphere of the earth, as well as water bodies on the earth (like rivers, ponds, lakes and oceans). This is because living organisms are found on land, in the atmosphere as well as in water bodies.
The animals living in the natural environment (like forests, etc.) are called wild animals. The wild animals are not domesticated by man. The plants growing in the natural environment on their own, are called wild plants. The wild plants are not cultivated (or grown) by man.
The term ‘wildlife’ means all the animals and plants which are found naturally in the forests and other natural habitats. Though the term ‘wildlife’ also includes wild plants but it is most commonly used for wild animals and birds.
The term ‘diversity’ means ‘a variety’. And ‘biodiversity’ means ‘biological variety’. Biodiversity refers to the variety of organisms (plants, animals and micro-organisms, etc.) found in a particular area or habitat. In other words, the presence of a large number of species in a particular area (or habitat) is called its biodiversity. Biodiversity denotes the richness of species in a particular area or habitat.
An ecosystem is a ‘system’ which includes all the living organisms (plants, animals and micro-organisms) of an area and the physical environment (soil, air and water) in which they live. In an ecosystem, the various living organisms interact among themselves (through food chains), and also with the physical environment in which they live. An ecosystem is a self-sustaining unit of living organisms and non-living environment, needing only the input of sunlight energy for its functioning.
The wild animals and birds are comfortable and flourish in their own, natural habitat (which is usually a forest).
The biggest threat to the existence and survival of wild animals and birds (or wildlife) is deforestation. Let us discuss deforestation first.
Deforestation And Its Causes
The clearing of forests (by cutting down forest trees) over a wide area is called deforestation. The forest land cleared of trees is used for other purposes. The various causes of deforestation (or cutting down of forest trees) are the following :
- The forest trees are cut down to obtain wood for using as fuel.
- The forest trees are cut down to obtain wood (timber) for making doors, windows and furniture.
- The forest trees are cut down to obtain wood for making paper.
- The forest trees are cut down to obtain more agricultural land for cultivation of crops for the increasing population.
- The forest trees are cut down to get land for building houses, factories, roads and dams, etc.
All the above causes of deforestation are the man-made causes of deforestation. There are also natural causes of deforestation (which involve the destruction of forests by natural processes). Some of the natural causes of deforestation are : Forest fires and Severe droughts.
Forest fires can burn down all the trees and other vegetation of the forest and cause deforestation. And when severe droughts occur, the forest trees die out because of lack of water. A great variety of organisms like plants and animals exist on the earth. These plants and animals are essential for the well-being and survival of mankind. Today, a major threat to the survival of organisms (plants and animals) on the earth is deforestation.
Consequences of Deforestation
The destruction of forests by the excessive cutting down of forest trees can make the forests disappear completely one day. The deforestation (or destruction of forests) will have the following consequences for us, other animals and the environment:
(i) Deforestation will lead to a shortage of wood and other forest products
The wood obtained from forest trees is used as a fuel ; for making doors, windows and furniture; and for making paper. Deforestation will lead to a shortage of wood for all these purposes. Forests also give us useful products such as honey, gum, sealing wax (lac) and catechu, etc. We will also face shortage of all these forest products if we continue to cut down forest trees.
(ii) Deforestation will cause an increase in temperature of earth’s atmosphere leading to global warming
Trees (and other plants) use carbon dioxide gas from the atmosphere for the process of food making called ‘photosynthesis’. When a lot of trees are cut down during deforestation, then lesser number of trees will be left. The lesser number of trees will use up less carbon dioxide due to which the amount of carbon dioxide in the atmosphere will increase.
In this way, deforestation increases the level of carbon dioxide in the atmosphere. Carbon dioxide gas traps the suns heat rays reflected by the earth (causing greenhouse effect). Trapping of heat rays by carbon dioxide increases the temperature of earths atmosphere. This will lead to global warming. The gradual increase in the over-all temperature of earth’s atmosphere due to greenhouse effect caused by the increased level of carbon dioxide in the atmosphere is called global warming.
The global warming can melt polar ice caps rapidly producing a tremendous amount of water leading to a rise in the sea level. The raised sea-water level will flood the low-lying coastal areas causing huge loss of life and property.
(iii) Deforestation will cause soil erosion making the soil infertile and lead to desertification
The roots of trees (and other plants) bind the particles of top soil together. Due to this binding of soil particles, the wind and water are not able to carry away the top soil easily. In this way, trees prevent soil erosion. The tree cover also softens the effect of heavy rains on the forest soil due to which the top soil does not become loose quickly. This is another way in which trees of the forest help prevent soil erosion.
When the forest trees are cut down during deforestation, there are no roots of trees which can bind the soil particles together and prevent them from being carried away by strong winds or flowing rain water. Moreover, since there is no tree cover on the soil to soften the effect of heavy rains, the bare top soil becomes loose quickly by the force of falling rain water and erodes rapidly.
Thus, fewer trees result in more soil erosion. The top layer of soil is the most fertile. The removal of top layer of soil during soil erosion, exposes the lower, hard and rocky layer of soil. This lower layer of soil has less humus and it is less fertile. Plants do not grow well in this less fertile soil. Gradually, the fertile land gets converted into a desert.
The process by which fertile land becomes desert is called desertification. Thus, deforestation is the cause of desertification.
(iv) Deforestation will cause frequent flooding of rivers leading to loss of life and property
The roots of forest trees (and other forest plants) help in absorbing some of the rain water and make it percolate into the ground. This reduces the amount of rain water which rushes quickly into rivers and flooding does not occur. When the forest trees (and plants) are cut down, the percolation of rain water into soil is reduced.
A lot of rain water from deforested soil rushes into the rivers quickly, causing floods. In this way, deforestation decreases the water holding capacity of soil which leads to floods. Another reason for the floods is the soil erosion caused by deforestation. The eroded soil is carried by flowing rain water into rivers. The eroded soil keeps on collecting on the river bed and decreases the depth of rivers gradually.
Due to decreased depth, the water-carrying capacity of the river is reduced. When heavy rains occur, the river is not able to carry away all the rain water quickly. The excess water overflows from the banks of the river into the adjoining areas causing floods. These floods damage standing crops, houses and even drown people living in nearby areas.
(v) Deforestation affects the water cycle leading to decrease in rainfall. The decrease in rainfall lowers the groundwater level and could cause droughts
The forest trees put a lot of groundwater, sucked through their roots, into the atmosphere as water vapour by the process of transpiration (evaporation from the leaves). This water vapour helps in bringing rain in that area. When the forest trees are cut down, then the lesser number of trees put less water vapour into atmosphere through transpiration.
Since less water vapour is put into the atmosphere, there is less rainfall in that area. When there is less rainfall in an area, then less water percolates into the ground. Due to this, the groundwater level also gets lowered. The shortage of surface water (in ponds, lakes, etc.) and groundwater due to persistent low rainfall in an area can lead to droughts (A prolonged period of abnormally low rainfall leading to severe shortage of water is called drought).
From the above discussion we conclude that as a consequence of deforestation, there will be increased chances of natural calamities such as floods and droughts.
(vi) Deforestation leads to the extinction of many wild animals and plants
Forests are the natural habitats of many wild animals, birds as well as plants. When forest trees and other forest plants are cut down, the natural habitat of wild animals and birds gets destroyed. These homeless wild animals fall prey to human beings and get killed.
Moreover, in the absence of forest trees and plants, the wild animals and birds do not get enough food and starve to death. In this way, many animal and bird species become extinct (or vanish) from that area. When forests are cleared during deforestation, many wild plant varieties growing in the forest also get destroyed.
We have just studied that deforestation reduces rainfall on the one hand and leads to floods on the other. These are two contradictory situations which can be explained as follows:
Deforestation reduces rainfall because less groundwater is put into the atmosphere (as water vapour) through transpiration. Deforestation leads to floods because:
- percolation of rain water into the soil is reduced, and
- soil eroded by rain water deposits on the river bed and decreases its water-carrying capacity.