4.01.2016

Land Degredation

Global Bilgiler  /  at  13:44  /  No comments

Contrary to popular perception, desertification is not the loss of land to desert or through sand-dune movement. Desertification refers to land degradation in arid, semi-arid and sub-humid areas resulting from various factors, including climatic variations and human activities. When land degradation happens in the world’s drylands, it often creates desert-like conditions. Land degradation occurs everywhere, but is defined as desertification when it occurs in the drylands.
Behind land degradation lies disturbance of the biological cycles on which life depends, as well as social and development issues. The term desertification was coined to convey this drama of pressing and interconnected issues in drylands.
The soil of degraded land has less capacity to support plant growth, resulting in the loss of vegetation and economic productivity. Despite the fact that animals and plants are able to adapt to the drylands, desertification has serious consequences for the environment. It is often caused by human activities, such as overgrazing, over-cultivation, deforestation and poorly planned irrigation systems. Extreme climatic events, such as droughts or floods, can also accelerate the process.
Depending on the type of agricultural technique employed, different forms of land degradation occur. For example, these can be:
• loss of nutritive matter (due to agricultural over-exploitation);
• loss of topsoil surface due to wind and water erosion, particularly due to the loss of vegetation;
• landslides caused by the action of water and the effects of vegetation loss;
• increased salinity and soil acidification due to irrigation malpractice; and
• soil pollution due to excessive use of chemical fertilizers.
Facts on land degradation
• Between 1981 and 2003, 24 per cent of global land was degraded.
• Rangeland accounts for 20 to 25 per cent of degrading land.
• Cropland accounts for 20 per cent of degrading land.
• Worldwide some 1 500 million people depend on degrading land.
• Between 1981 and 2003, 16 per cent of degraded land was improved.
• Rangeland comprised 43 per cent of degraded land.
• Cropland comprised 18 per cent of degraded land.
• Land covering 12 million hectares, equivalent to Bulgaria or Benin, is lost every year.
• Annual land lost could produce 20 million tonnes of grain.
Desertification occurs because dryland ecosystems are extremely vulnerable to over-exploitation and inappropriate land use. Poverty, political instability, deforestation, overgrazing and improper irrigation practices can all undermine the productivity of the land. There is no linear process of cause and effect leading to land degradation in the drylands, but its drivers, which interact in complex ways, are known. Such drivers are climatic, especially low soil moisture, changing rainfall patterns and high evaporation. Most of them are human-related, and include poverty, technology, global and local market trends and socio-political dynamics. It is important to note that poverty is both a cause and consequence of land degradation. Other consequences of desertification include:
• diminished food production, soil infertility and a decrease in the land’s natural resilience;
• increased downstream flooding, reduced water quality, sedimentation in rivers and lakes, and silting of reservoirs and navigation channels;
• aggravated health problems due to wind-blown dust, including eye infections, respiratory illnesses, allergies, and mental stress;
• loss of livelihoods forcing affected people to migrate.
There is a fine line between drylands and deserts – once crossed it is hard to return. It is much more cost-effective to prevent drylands from degradation than to reverse it. Restoring soil lost by erosion is a slow process. It can take 500 years for 2.5 centimetres of soil to form but only a few years to destroy it. Although the figure varies a great deal depending on how costs are measured, estimates by UNEP in 1993 suggested that desertification and drought account for USD42 000 million income lost worldwide every year, equivalent to all official aid to Africa in 2009. On top of this figure is
the uncountable cost in human suffering and lives lost due to hunger and the need to abandon once-productive land. Not only are these statistics disturbing, they can be prevented.
Between 1981 and 2003, 24 per cent of the land has been degraded globally.
About 1 500 million people depend directly on these degrading areas. Nearly 20 per cent of the degraded land is cropland, and 20 to 25 per cent is rangeland.

Despite the grave problems of drylands, such regions are areas of great potential for development. The fact that more than half the world’s productive land is dryland emphasizes the critical importance of wise management at the global, national and local levels. Impoverished land and impoverished people are two sides of the same coin. Sustainable land management can support land users to respond to changing market demand with adapted and traditional technologies to generate income, improve livelihoods and protect ecosystems.

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