Meaning of Deforestation:
Destruction of forest is called deforestation. Deforestation has serious effect on human life and environment.
According to a survey of forest department, India has about 75 million hectares of forest area.
Recently collected satellite imagery data have revealed that only about 17 per cent area is covered by forest. India is loosing 1.3 million hectare of forest every year. In the hilly region deforestation is so acute that economy and ecology of the area are severely affected.
The original vegetation of Himalaya has been greatly destroyed which has resulted in gradual loss of the natural habitat and is posing a threat to natural resources. Due to overpopulation, industrialization, urbanization, road construction, mining and other developmental activities the natural habitats of the flora and fauna are disturbed which have caused tremendous pressure on the living resources.
Many plant and animal species are on the verge of extinction or endangered. Forest destruction may also be caused by several adverse factors as landslides, drought, flood, storm, earthquakes, diseases, water and air pollution and human interferences. Other adverse factors such as lack of stable soil, aridity, swampiness, biotic agencies, commercial exploitation, etc. may also be responsible for depletion of forest vegetation. Natural diversity of India is one of the richest in the world which is disappearing gradually due to aforesaid factors.
According to FAO report, the annual deforestation rate in India was 0.6 per cent (0.34 million hectares during the period 1981 to 1990). According to Ravindra Nath and Hall (1994) 1.44 million hectares was afforested every year. In 1990, the total afforested area in India was 70.6 million hectares of which 27 per cent was under commercial plantations consisting mainly of Eucalyptus, teak and pine.
According to Khoshoo (1986), the total area under forest in the world was about 7000 million ha. In 1900, by 1975 it was reduced to 2890 million ha. The destruction of forest cover in the ecologically sensitive Himalaya region has already started showing adverse impact in the form of increasing shortage of water, recurrent landslides, increasing flood, high sedimentation in the rivers, shortage of fuel and fodder and decrease in grazing land Due to deforestation the life supporting systems are disturbed. Underground water table is progressively going deeper and deeper. Large area of the land becomes affected by drought and wells, tube- wells, lakes, ponds etc. dry up sooner than expected during summer months.
In Kumaon and Garhwal Himalaya the oak forests are maintaining general environment and villagers depend to a great extent for fodder, fuel and some other necessities on these forests. But now oak forests are being destroyed to meet the ever increasing demands of the people. This has resulted marked changes in the environmental conditions.
Consequently, the herbal vegetation and microbial community associated with oak are destroyed. This may lead to the loss of medicinal herbs and shrubs associated with oak. The availability of fodder will be reduced and the age-old animal link in the hill ecosystem would be broken.
At the Earth Summit in Rio de Janeiro (1992), issue related to deforestation was a major concern. The Agenda 21 of the UNCED (United Nation Conference on Environment and Development) stated: “Deforestation is a result of many causes; some natural, but others mainly due to human development, such as inappropriate land tenure systems and incentives, expansion of agricultural areas, increasing forest product demand and lack of information about and understanding of the value of forests.”
A review of available literature has revealed the following facts about Indian forests:
1. The sustainably extractable quantity of fuel wood from Indian forests is far below the requirement of the population.
2. Livestock population in India is greater than can be sustainably supported by the available land and forest resources.
3. The demand for industrial wood and other wood, part of which is currently being met by imports, will continue to rise with industrial and economic growth.
4. Unregulated and increased harvesting of non-wood forest produce will result in loss of biodiversity.
5. Expansion of protected area network will result in increasing pressures on the existing productive forests.
Causes of Deforestation:
The different causes of deforestation are as follows:
Overgrazing in forests destroys newly regenerated growth. It also makes soil more compact and impervious. Soil becomes less fertile due to destruction of organic matter. Seeds of certain species do not germinate in excessively grazed soils which results in reduction of species. Overgrazing also leads to desertification.
Domesticated animals are thus deprived of their natural grazing and forage support. Overgrazing also accelerates the soil erosion. Soil erosion results in the removal of minerals and nutrients from the top soil and adversely affects the soil structure which ultimately lowers the productivity.
Satellite imagery data indicate that the area under pasture land is severely degraded. The uncontrolled and indiscriminate grazing in the forests lead to degradation of forest soil and affect natural regeneration of forests.
2. Shifting cultivation:
This is most common in North-Eastern India due to heavy water erosion shifting cultivation is locally called Jhum. Many farmers destroy the forest for agricultural and commercial purposes and when fertility of soil is exhausted due to repeated cropping, a new forest area is destroyed. Therefore, farmers should be advised to use the same land for cultivation and apply improved farming methods. It is estimated that every year about one million hectare land is degraded by shifting cultivation.
3. Fuel wood:
Maximum destruction of forest vegetation is done for fuel wood. Of the total fuel wood nearly 85 per cent is used in rural areas and 15 per cent in urban areas. The annual fire wood consumption was 134 million tonnes in rural areas and 23 million tonnes in cities in 1987 According to an estimate of Forest Survey of India (1987), the annual demand for fire wood in the country was 235 million cubic metres. Thus fuel wood is a major factor for deforestation.
4. Forest fires:
Frequent fires are the major cause of destruction of forests in India. Some fires are incidental while the majority of them are deliberate. According to a study conducted by the Forest Survey of India (1996), on an average, 53.1% forest vegetation is affected by fire. Data further indicate that fire destroys about 0.5 million hectares of forests annually.
Timber and plywood industries are mainly responsible for the destruction of forest trees. Thus the increased demand for timber led to a rapid depletion of forest. According to Forest Survey of India 1987, against an annual demand for more than 27 million cubic metres the permissible cut of timber from forests was only 12 million cubic metres.
6. Industry establishment:
Sometimes factories are established after destruction of forest. Thus for a small gain there is an irreparable loss. In this process precious plant, wild animals and rare birds are destroyed and the quality of environment is adversely affected. A factory should be established on a waste land away from the urban population. Supply of raw materials to the forest based industries is another major cause of forest destruction in the hills. The forest based industries such as Resin and Turpentine industry are also responsible for destruction of trees in the hills.
7. Encroachment of forest:
Another cause of deforestation in India is encroachment by tribals on forest land for agriculture and other purposes. According to Forest Survey of India, about 7 million ha of forest land has been encroached for agriculture. Although such land makes a good contribution for agriculture production yet it produces environmental hazards. So it is not desirable to convert forest land into agriculture land.
8. Forest diseases:
Many diseases caused by parasitic fungi, rusts, viruses and nematodes cause death and decay of forest plants. Young seedlings are destroyed due to attack of nematodes. Many diseases such as heart rot, blister rust, oak will, phloem necrosis and Dutch elm disease, etc. damage the forest trees in large numbers.
9. Land slide:
Deforestation due to land slide in the hills is of great concern. It has been observed that, the land slide occurred mainly in the areas where developmental activities were in progress for past few decades. The construction of roads and railways particularly in hilly terrains, setting up of big irrigation projects have caused enough destruction to forest and accelerated the natural process of denudation.
10. Ravine formation:
The forests and cultivated lands along the sides of ravines of big rivers (Yamuna and Chambal) are facing a serious danger of soil erosion. Once the ravines are formed, they continue to destroy the vegetational cover.
11. Increase in population:
The population of India which was 36 crores in 1951 is expected to touch 1.05 billion (105 crores) by 2010 A.D. The number of persons dependent on one hectare of agricultural land increased from 3 in 1960-61 to 5 in 1990-91. Such an increase has resulted in acute shortage of land. Besides agriculture, forest land has also been diverted into other sectors. Table 16.2 gives an idea about diversion of forest land into different sectors.