However, it was not until 1998 that enough signatories drew their pens to ratify the Convention to Combat Desertification , the major components of which are national and international proposals to combat land degradation. These pressures on land are compounded by the fact that over 69 per cent of our geographical area falls within dry zone as per the Thornwaite classification. The capacity of these lands is limited due to environ-mental factors. Introduction of leguminous crops, 13. A global assessment of land quality. This often causes over-exploitation of the natural resources, and contributes to environmental erosion.
Many researchers argue that this definition of desertification is too narrow because severe land degradation resulting from anthropic activities can also occur in the temperate humid regions and the humid tropics. World Map of the Status of Human-induced Soil Degradation: An Explanatory Note. Removal of vegetative cover and overgrazing enhance the intensity and extent of wind erosion and desertification. In Morocco, for example, erosion is so extensive that the petrocalcic horizon of some Palexeralfs is exposed at the surface. The quantity and quality of vegetation are not considered.
A wide range of terms is used in the literature, often with distinct disciplinary-oriented meaning, and leading to misinterpretation among disciplines. Removal of even a portion of the canopy changes the environment of the forest as the canopy blocks the harmful sunlight and keeps in heat at night. This has led to serious problems as animals have encroached into forest lands and even agricultural lands. This occurs either through direct clearing and replacement of native vegetation by overgrazing, by changes in water availability and salinisation, or simply by the failure of the native species to recruit new individuals to replace those that die. They are in urgent need of attention and have to be accorded the highest priority for treatment under watershed programmes. Although the system above seems like a positive feedback scenario, land degradation and desertification are more likely to operate on a negative feedback method, whereby eventually the system will revert back to its original position albeit having crossed a number of thresholds and experienced a few positive feedbacks during its cyclical journey.
These people include many of the world's poorest, most marginalized, and politically weak citizens. Stressed Agroecosystems and Sustainable Agriculture. Desertification Desertification is a form of land degradation occurring particularly, but not exclusively, in semi-arid areas. This is measured through a base line in the form of pre- existing risk of crisis or destruction. Major Causes Of Land Degradation Major Causes of Land Degredation Land degradation is any change in the condition of the land which reduces its productive potential. A number of studies in India and Nepal have established that the increased demand for food, livestock and firewood is the direct cause of deforestation.
Declining aquifer levels and concerns that groundwater quality will degrade in the future suggest that this aquifer cannot sustain current water use in the long term McGuire, 2009; Scanlon et al. The thrust of a new agenda for resource assessment and monitoring with respect to land degradation including desertification , has several components. It is bounded by Shivalik and Himalayan ranges on one side and Ganga and Yamuna on the other. International Journal of Tropical Agriculture, 5, 77—92. Groundwater abstraction augments surface water supply for large-scale irrigation of crops, particularly rice and wheat, in the Indus, Ganges, Yangtze, and Yellow river basins at rates that generally exceed both natural and return-flow recharge Immerzeel and Bierkens, 2012. The 1999 Forest Survey of India placed the actual forest cover at only 19. An ever-increasing population places enormous demands on land resources.
This reduces the ability for plants to grow and water to penetrate, which harms soil microbes and results in serious erosion of the land. Interactions between the two systems determine the success or failure of resource management programs. They should develop early warning indicators of degradation to enable them to collaborate with others, such as social scientists, to develop and implement mitigating technologies. However, deforestation activities can be mitigated and altered reshaping and restoring forests and vegetative cover. If we are not careful, we can contribute to the environmental degradation that is occurring all around the world. Oxford Press, New Delhi, India.
Over-Irrigation: Big irrigation projects no doubt have brought prosperity to millions of farmers. This hampers the land immensely. Soil is a complex body and forms the thin outer layer of the earth. In spite of concerted efforts to check deforestation and the various afforestation schemes taken up during successive Plan periods, large tracks of forest continue to be classified as degraded. Due to environmental degradation, the results include water scarcity and decline in quality foods. Improper land use has led to the loss and destruction of millions of acre of natural environments across the globe.
The mineral processing, like grinding of limestone for cement industry, and calcite and soapstone for ceramic industry, generates heavy amount of dust and releases it in the atmosphere. Criteria for designating different classes of land degradation e. The sodic soils possess high pH and exchangeable sodium percentage values, preponderance of carbonate and bicarbonate salts of sodium, deficient amount of organic matter, nitrogen, available calcium and zinc, presence of CaC0 3 kankar in the subsoil, impaired physical condition and poor moisture relations. Yet, it is an old problem e. Besides natural causes, there are some human activities also, which cause degradation of land. Overcrowded landfills: Each household produces tonnes of garbage each year. Principal processes of land degradation include erosion by water and wind, chemical degradation comprising acidification, salinization, leaching etc.
The mining sites are abandoned after excavation work is complete. This problem varies from overgrazing in rangeland, to water and wind erosion in rainfed croplands, and to salinization in irrigated lands. Land degradation leads to the removal of soil compostion which which plays a role in water retention and absorptions. This shows the seriousness of land degradation. Whereas soil loss ranged from 330 to 1,478 t ha-1, the corresponding yield of rice ranged from 4.