4 Regulation of hydrological Cycle: Forested watersheds act like giant sponges, absorbing the rainfall, slowing down the runoff. They control climate through transpiration of water and seed clouding. Soil Conservation: Forests bind the soil particles tightly in their roots and prevent soil erosion. They also act as wind breakers. Pollution moderators: Forests can absorb many toxic gases and can help in keeping the air pure and in preventing noise pollution. OVER EXPLOITATION OF FORESTS Man depends heavily on forests for food, medicine, shelter, wood and fuel. With growing civilization the demands for raw material like timber, pulp, minerals, fuel wood etc. shot up resulting in large scale logging, mining, road- building and clearing of forests. Our forests contribute substantially to the national economy. The international timber trade alone is worth over US $ 40 billion per year. The devasting effects of deforestation in India include soil, water and wind erosion, estimated to cost over 16,400 cores every year. Ecological Significance of Forests 1) Balances CO2 and O2 levels in atmosphere. 2) Regulates earth temperature and hydrological cycle 3) Encourage seepage and reduces runoff losses, prevents drought 4) Reduces soil erosion (roots binding), prevents siltation and landslides thereby floods 5) Litter helps in maintaining soil fertility 6) Safe habitat for birds, wild animals and organisms against wind, solar radiation and rain. DEFORESTATION Deforestation refers to the loss of forest cover; land that is permanently converted from forest to agricultural land, golf courses, cattle pasture, home, lakes or desert. Causes for Deforestation Agriculture: Conversion of forests to agricultural land to feed growing numbers of people. Commercial logging: Destroys
5 The cash crop economy: Raising cash crops for increased economy. Mining Increase in population: The needs also increase and utilize forests resources. Urbanization & industrialization Mineral exploration Construction of dam reservoirs Infrastructure development Forest fires Human encroachment & exploitation Pollution due to acid rain Environmental effects /Consequences of deforestation Food problems Ecological imbalance Increasing CO2 Floods leading to soil erosion Destruction of resources Heavy siltation of dams Changes in the microclimate Loss of biodiversity Desiccations of previously moist forest soil Environmental pollution Global warming CONSERVATION Conservation derived from two Latin words, con – together, servare – to keep or guard measures, i.e. an act of preservation or to keep together. Concepts in conservation Restraining cutting of trees and submerging the forests Reforestation Afforestation Control forest diseases and forest fire Recycling forest products
6 Replacing forest products TIMBER EXTRACTION AND MINING The major activities in forest area are 1) Timber extraction 2) Mining The important effects of timber extraction are i) Thinning of forests ii) Loss of biodiversity, particularly tree breading species iii) Soil erosion and loss of soil fertility iv) Migration of tribal people from one place to another in search of new forest v) Extinction of tribal people and their culture Mining is a process of removing ores from area which is very much below the ground level. Mining is done for the extraction of several minerals of metals like Fe, Mn, Au, Ag, etc. The minerals are especially found in thick forests. Mining can be carried out in two ways 1) Surface mining 2) underground mining or sub-surface mining The effects of under ground mining on forest reserves are comparatively less than that of surface mining. DAMS – BENEFITS AND PROBLEMS River valley projects with big dams are considered to play a key role in the development of a country. India has large number of river valley projects. 1. These dams are regarded as symbol of national development. 2. Provides large scale employment of tribal people and increase the std. of living of them 3. Contribute for economic uplift and growth 4. Help in checking flood 5. Generate electricity 6. Reduce power and water shortage 7. Provide irrigation water 8. Provide drinking water to remote areas 9. Promote navigation and fishery.
7 CASE STUDIES 3.6.1 Desertification in hilly regions of the Himalayas: Desertification in Himalayas, involving clearance of natural forests and plantation of monocultures like Pinus roxburghi, Eucalyptus camadulensis etc., have upset the ecosystem by changing various soil and biological properties. The area is invaded by exotic weeds. These areas are not able to recover and arev losing their fertility. 3.6.2 Disappearing Tea gardens in Chhota Nagpur : Following the destruction of forest rain fall declined in Chhota Nagpur to such an extent that teagardens also disappeared from the region. 3.6.3 Waning rain fall in Udhagamandalam : The rainfall pattern was found to fluctuate with wooded land area in the hills. When the Nilgiri mountains had luxuriant forest cover annual rainfall used to be much higher. WATER RESOURCES Water is an indispensible resource. Around 97% of world surface is covered with water. Most of the animals and plants have 60-65% of water in their body. Unique features of water: High specific heat High latent heat of vapourisation Good solvent for oxygen, nutrients and pollutants Anomalous expansion on freezing High surface tension Global distribution of water is very much random depending on the geographical conditions. The availability of water decreases in the following order. Tropical rain forest Temperate regions Deserts