The estimated forest cover in different states of India (as in 1980) gives a more recent estimate (vide infra). India has a fairly considerable potentiality for increasing the supply of such renewable resources as forests and forest products that could substitute for some of the scarce nonrenewable resources.
Thus wood and wood products may be substituted for the nonrenewable fuel and energy sources, as has been commonly practised in villages since times immemorial. Wood has certain advantages as fuel. As compared to coal, its sulphur content and ash content are very low. The resulting ash can be used as a fertilizer. However, as compared to fossil fuel, the moisture content of fresh wood is very high and this reduces its heat value. This disadvantage does not apply to dried wood.
Wood and vegetable fibres might also someday furnish us certain primary organic chemicals. India and other tropical countries have particularly abundant timber and hardwood resources. In these countries, wood residues may profitably be converted into liquid and gaseous fuels; this can relieve, to some extent, the problem of scarcity of large-scale exploitable oil and coal resources.
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According to a 1991 assessment (The State of Forest Report-1991) the forest cover in the country is 6, 39,182 sq. kms. (Excluding tea gardens). It amounts to 19.44% of the total geographical area of the country (See Table 10.2 A). In recent years there has been a slight decline of forest cover in Arunachal Pradesh, Assam, Gujarat, Meghalaya, Nagaland, Orissa, Punjab and Uttar Pradesh.
There has been a slight increase in the forest areas of Karnataka, Meghalaya, Mizoram, Nagaland, Orissa, Punjab and Rajasthan on account of regeneration and conservation measures. As a result, there has been a net increase of 550 sq. kms. in the forest cover of the country (The State of Forest Report, 1991).
Out of the available district maps of 413 districts in the country, 105 districts have 33% of their geographical area under forest cover, 52 districts have forest cover ranging between 19% to 33% while 217 districts are having forest cover upto 19%. 39 districts do not have any discernible forest cover.
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‘Timber’ or wood can be defined as the merchantable boles of forest trees at least 12.5 cm in diameter at breast height and including all the wood above a 30 cm stump and extending up to a 10 cm top.
Timber accounts for some 25 per cent of all the photosynthetic material produced on earth and about one- half of the total biomass produced by a forest is constituted by timber.
Structural wood products and fibre products constitute the major kinds of products derived from timber. Examples of structural products include lumber, plywood, boards, and other building materials.
Two important examples of fibre products are pulp and paper. Apart from these, some other relatively minor products derived from timber or wood include oils, tannins, chemicals, and energy.
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The fibrous agricultural residues and other nonwood plant fibres can be used for the same purpose as wood, especially for the manufacture of pulps, paper, paperboards and panelboards, chemicals, and for generation of steam and power.
Most of the wastepaper can be effectively recycled. Nonwood plant fibres constitute one of the major, though neglected, sources of fibrous raw material for many developing countries.
These fibres include agricultural residues, e.g., sugarcane bagasse, cereal straw and hay; natural growing plants, e.g., reeds, bamboos, and certain grasses, and nonwood crop fibres grown primarily for their fibre content, e.g., bast fibres such as jute, hemp, ramie, okra; leaf fibres, such as manila hemp, sisal and henequen; and cotton fibres, cotton linters, and cotton rags.
Sugarcane bagasse is one of the most important and abundant nonwood plant fibres (see Atchison, 1976). It can be used for digestion into pulp relatively easily since unlike most other fibres, it only needs to be depithed; for other fibres, various additional steps are required, besides depithing, to prepare them for the pulp digester. Various kinds of bagasse pulp being now produced commercially vary from the mechanical type pulp used for insulation boards, to the high quality shining, bleached pulp used for making superior quality paper.
In fact, bagasse pulps now constitute the chief component in the manufacture of wide variety of papers used for wrapping, printing, writing, toilet tissues, corrugating medium, etc. It is also used as a fuel in sugar industry.
Most of the world’s bamboo pulp and paper industry is located in India, with some bamboo pulp also being produced in Burma, Thailand, Pakistan, with pulps of lower tear but higher tensile strength.
Currently available organic waste products are of immediate interest from the viewpoint of energy generation. Using dry biomass as a renewable resource it is possible to generate energy in the form of solid fuel, gases (CO2, CO, H2, CH4), methanol, ammonia and other chemicals. Fuel oils can also be obtained in the process.
Agricultural wastes can sometime be used or processed for use as animal feed, often in supplementation with some urea which relieves protein deficiency in cattle.