Deforestation is decrease of forest cover of an area. World forest cover of 7000 million hactares has been reduced 2400 million hectares in 2000.
It is estimated that about 40% forests have been lost in the tropics compared to 1% loss in temperatre regions.
In India, at the beginning of 20th century forest cover was about 30% of the total land. By the end of the century, it shrunk to 19.4%, where as National Forest Policy (1968) of India has recommended 33% forest cover for the plains and 67% for the hills.
Causes of Deforestation:
1. Jhuming:
Slash and burn agriculture is commonly called as Jhum cultivation. In this process the farmers cut down the trees of the forest and burn them. The ash is used as a fertilizer and the land is then used for farming. After cultivation, the area is left for several years so as to allow its recovery. The farmers then move to other areas and repeat this process. Technically it is called as shifting cultivation.
2. Hydroelectric Projects:
Man made dams, reservoirs and hydroelectic projects submerge forest areas, killing all plants and animals.
3. Forest fire:
Huge forest fires in dry seasons destroy large patches of forests.
4. Human Establishment:
There is an increasing demand for agricultural land in order to grow more food crops for feeding the growing human population which is done through clearing forest areas. Forest land is also used for building more residential complexes and industrial townships.
5. Mountain and Forest Roads:
Construction of roads and railway tracks in hilly forested areas results in lot of deforestation, landslides and soil erosion.
6. Canals:
Canals constructed for irrigation under irrigation projects destroy lot of forest areas and cultivated land.
7. Overgrazing:
The population of livestock in India is about 500 million but grazing area is only 13 million hectares. One hectare of land supports only 6 livestock. The remaining naturally graze in forests causing destruction of seedlings and causing compaction of soil. The latter reduces water holding capacity and increases run off. Ultimately huge forest area is destroyed.
8. Wood Demand:
Requirement of wood is rising for fuel, house construction and paper industry leading to loss of several million hectares of forest area.
Effects of Deforestation:
1. Increase in carbon dioxide concentration in atmosphere.
2. Deforestation results in reduced rainfall, increased draught, hotter summer and colder winter.
3. Soil is exposed to insolation, dries up and gets eroded by wind and water.
4. Timber and fuel wood availability has been drastically reduced. Forest products like resin tannin, gums, latex, lac may not be available.
5. Loss of forest leads to soil erosion and finally desertification occurs which is of no use Moist and fertile land of forests will be converted to deserts due to decrease amount of rainfall and no floods.
6. Deforestation would result in loss of biodiversity and germplasm having devastating effect in ecological balance.
Difference between Deforestation and Desertification:
Deforestation:
i. It is decrease or removal of forest cover.
ii. Amount of rainfall is reduced.
iii. Temperature moderation potential is reduced
iv. it leads to soil erosion.
v. Deforestation causes flash floods.
Deforested land can be used variously as crop land, industrial area, residential area etc.
Desertification:
i. It is conversion of moist and fertile land into arid desert area.
ii. Amount of rainfall is much less than evaporation
iii. Temperature is either high or low.
iv. Desertification is a product of soil erosion.
v. Flood do not occur.
vi. Decertified land cannot be put to any use.
Conservation Strategies:
1. Public awareness:
Public movements like chipko agitation, Tehri Dam development, silent valley movement etc. have created awareness among common man to save forest and save nature.
2. Social forestry:
It is an attempt to increase green coverage through forestry by the people, of the people and for the people. Plantation of trees in schools and colleges through Van Mahotsava, tree plantation in road sides, barren lands, canal sides, public parks and picnic spots etc.
3. Agroforestry:
It is a system of growing plants (forest trees) with agricultural crops.
Agroforestry includes:
(i) Agro-silviculture – tree, crop plants, medicinal herbs, fruit plants are groomed together.
(ii) Agro-silvo-pastoral practice – trees, crops, grasses and sedges are grown together,
(iii) Silvo-pastoral practice – Forest, trees, grasslands are raised together
(iv) Socio-agro-silviculture – coffee, rubber, paper pulp producing trees, crop plants and forest trees are grown together.