4.01.2016

Drivers of desertification

Global Bilgiler  /  at  13:48  /  No comments

Land degradation reduces or destroys soil productivity, vegetation, arable and grazing land, as well as forest. In the most extreme cases, hunger and poverty set in and become both the cause and consequence of further degradation. While this book seeks to present a wide range of causes and impacts to foster understanding of desertification, it is by no means exclusive.
Further it is important to recognize that issues can only be generalized to a certain extent beyond which, each country and region must be viewed in their individual context.
 Climatic variations
Drought means the naturally occurring phenomenon that exists when precipitation has been significantly below normal recorded levels, causing serious hydrological imbalances that adversely affect land resource production systems. High, sustained temperatures lasting for months with infrequent and irregular rainfall lead to drought and difficult growing conditions for plants and trees. As a result, severe hydrological imbalances jeopardize natural production systems. When violent winds and heavy downpours destroy the vegetation carried away by the sudden gush of water harvests and livestock suffer. As a consequence, the income of the rural communities diminishes.
Human activities In countries where major economic resources are dependent on agricultural activities, there are few alternative sources of income, or none at all. Soil is damaged by excessive use when farmers neglect or shorten fallow periods, which are necessary to allow the soil to recover sufficiently to produce enough food to feed the population. This in turn causes the soil to löse organic matter, limiting plant growth and reducing vegetation cover. The bare soil is more vulnerable to the effects of erosion. Four human activities are the most immediate causes:
• Over-cultivation exhausts the soil;
• Overgrazing removes the vegetation cover that protects it from erosion;
• Deforestation destroys the trees that bind the soil to the land; and
• Poorly drained irrigation systems turn croplands salty.

Extractive industries advance land degradation by lowering water tables, disturbing land and accelerating soil erosion. Inadequate knowledge on sustainable land management, unfavourable trade conditions in developing countries, non-ecological tourism and other socio-economic and political factors, which intensify the effects of desertification, create another form of impact. These factors interact with the causes above and are often the underlying drivers of man-made desertification.

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