Archives – March, 2011

Desertification characteristics:

Based on the last definition of desertification presented to the Inter-Governmental Convention on Drought and Desertification control Committee (CCD) and ratified by its members on 26 December 1996 (UNEP, 1997), the only difference between desertification and land degradation is considered the climatic restrictions of the affected zones. In other words, while climatic factors never contribute to land degradation, a part of its function in the fragile climatic zones of dry lands (except hyper arid zones) is called desertification[1]. Therefore, from the total of 13012.6 million hectares of the lands of the earth that can undergo the land degradation trends, approximately 5169.2 million hectares or 39.7% are potentially affected by desertification.

Therefore, it is concluded that two conditions are essential although not enough for the occurrence of desertification in every land; 1) the discussed area have the minimum potential for production[2]; 2) the production potential of the land have not exceeded certain limits[3].. Thus 978.1 million hectares of lands of the earth because of not having the first and another 6875 million hectares because of not fulfilling the second conditions are out of the boundaries of desertification trend. But the necessary condition is an external factor that causes change and degradation of the environment; a change that is generally irreversible. This external factor is assumed the result of natural pressures such as climatic changes or human pressures. However; while the climatic changes generally happen in the scale of geological ages, the desertification process degraded and deteriorated more than 5 billion hectares of productive lands (38.5% of all lands of the earth) with a hasty growth (Daily, 1997); therefore as mentioned above, humans are the most important factor of happening and intensification of desertification in the world, a creature that have most suffered from this process himself[4]. On the other hand if we even accept that the natural factors are effective in the happening of desertification, only the human factor can slow down or stop the desertification trend (FAO/UNEP, 1984). This is a fact that should always be considered in the introduction mechanism of desertification criteria and some factors should be selected regarding the interactions among the criteria and the human functions.

[1] The reason for using another scientific term instead of land degradation goes to the incentives and more feeling underlying the word desertification which take more attention unconsciously (Le Houerou, 1998 and Horstmann, 2002); though this attention have most often led the people and authorities to assume desertification as a synonym to the physical expansion of natural deserts and ignore the main invisible reducing trend of soil productivity in more humid areas; a misunderstanding, the result of which is observed in the designation of wrong criteria and factors for desertification (Ekhtesasi and Mohajeri, 1997).

[2] It means that the annual average precipitation of the region is less than 5% of the annual average evapotranspiration (Wolfe, 1997).

[3] The definite limit is designated as annual average precipitation lower than 65% of the annual average evapotranspiration (Wolfe, 1997).

[4] The bitter satire is the unwise management of resources by the wisest creature (human) on the earth!

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