DESERTIFICATION - The phenomenom


Desertification is a phenomenon of soil degradation of arid, semi-arid and sub-humid areas, due to a combination of climatic and anthropogenic, which is essentially a progressive reduction in the capacity of ecosystems to sustain plant and animal life. It is the result of a series of processes that affects all zones, not only arid and arid, the planet and that includes wind erosion and hydraulic, sedimentation of materials eroded, the progressive reduction of the number of plant species present in a given area, soil salinisation and mineralization of humus. It causes a progressive reduction of the surface layer of the soil and of its productive capacity.



According to the UN, there are about 110 countries suffering from desertification. The phenomenon is often associated with the idea of ​​sand dunes advancing, devouring green areas and fertile. In fact also applies to areas that are heavily irrigated or located at latitudes far removed from the desert regions. The problem is particularly acute in Africa and the developing countries of Asia, China, Latin America and the Caribbean, United States, Australia, Southern Europe and Eastern Europe are directly affected by the phenomenon. In Europe in particular interested with intensity and extent different European countries bordering the Mediterranean basin including the regions of southern and insular. In developed countries in general, the context of the fight against desertification is of course very different from that of the countries in the developing world where the problem is posed in terms of survival and trying to find a solution that is an alternative to emigration and abandonment of the territory. The deserts are expanding in almost all over the world and this is one of the most alarming processes of generalised degradation of arid and semiarid areas. Desertification is due to both anthropogenic causes, and natural causes, resulting from climate change. The relationship between the expansion of the desert and an increase in precipitation is in the fact that the higher humidity leads to the development of new plant species more demanding, which supersede the previous more frugal. When the rainy season ends on the new vegetation dies because it does not fit the return of the dry climate.

Agriculture in sub-arid areas

In recent decades, subsistence agriculture for areas sub-arid has been abandoned for 3 main reasons:

  • The creation of national borders that have reduced the chances of moving the nobles.
  • The increase in population has led to a sharp increase in food needs.
  • The extension of the crops of industrial type that leads to increased exports.

This has resulted in the elimination of the rest periods of the soil. To this is achieved the fall of the productivity of land, and later their abandonment.



The over-exploitation of grazing land is one of the main causes of desertification: when the amount of livestock is higher than the ability to offer that pastures can support, land degradation begins. Perennial plant species are replaced with annual species and shrubs unwelcome livestock, and then disappear herbaceous species, poaching of animals also destroys what little remains and the soil is so subject to the erosive action of wind and water. Similarly, over-exploitation of agricultural land leads to a progressive impoverishment of the land that once depleted their reserves of nutrients, remain exposed to the weather and are therefore subject to erosion. The process of desertification can be caused also by indiscriminate reduction in forest cover or the mismanagement of irrigation systems, which in many regions is due to the salinisation of soils. The land which is not allowed to stand or are machined too deep by mechanical means and those grown in monoculture, gradually lose their fertility and may be subjected to erosion.

In temperate areas is frequent abandonment of previously cultivated lands. The soils abandoned are in a short time subject to erosion. The vegetation changes. Species were cultivated replacing a kind of bushy vegetation, which rarely reaches the lushness of other crops, which remain uncovered large spaces where the erosion process can manifest itself with particular intensity. In tropical areas the phenomenon is even more striking because of the intense deforestation is that there is in place. The heavy rains, characteristic of tropical areas, erode the soil no longer protected by the trees until the clay cemented surfaces, which is formed at a depth of 2-3 meters, which is totally unproductive.

Abandoned land in developed countries

Now two-thirds of the world population lives on the coast. In Europe and other developed countries there has been an overcrowding lowland areas. Even in the plains, however, especially near urban areas there are cases of uncultivated land. In Britain and partly in Ireland the problem is almost non-existent. In Italy, the abandoned lands greatly exceed the 2 million hectares. The various regions seek to provide themselves legislative instruments suitable to tackle the problem.

Intensive farming in areas not suitable

In the seventies, in Europe and North America take hold various movements of opinion involved in helping the developing tropical countries. One of the favourite forms of aid was to acquire and donate whole herds of cattle, in the belief that hunger would be defeated by providing the means to procure milk by cattle, instead of the same milk and food. The sparse bushes present in those areas, however, may only supply a limited amount of cattle, while an excessive number of heads causes the total destruction of the turf, until the removal of root systems, thus transforming the area into a desert area.


The price to halt the advance of the desert would not exceed $ 2.5 billion a year. However, the funds made available so far for developed countries and developing countries do not come to a quarter of that number. One of the main reasons for the phenomenon is that the affected people have not the slightest social importance, as their lands are unproductive and do not have any influence in the political-economic structure of their countries. It is mostly of farmers whose economy is subsistence and who have no voice in policy decisions. National leaders know that these people will never pose a threat to the system, if ignoring her needs. The governments decide to spend too much money in arid areas only, when they are born different problems. In the Horn of Africa, for example, towards the end of the sixties poor peasants of Ethiopia and Somalia began to walk towards the semi-desert lands of Ogaden. When the two sides clashed to conquer new habitats, a war broke out the border. Under normal conditions, the territory covered by shrubs would have been ignored by the rest of the world. But because he was very close to the Gulf oil routes invested a lot of money on arms. That money would be more than enough to restore vitality to the degraded lands of the two countries, and to stop the process of desertification along much of the entire border of the Sahara. Some unique and useful initiatives have, however, contributed to slowing down the process of desertification in some regions at the edges of the Sahara, for example, were implanted “vegetable belt” formed by rows of trees particularly resistant: in the Sahel this practice has allowed hew out of the 620 hectares of land desertification (60 of which have even been recovered agriculture) and to save some villages that would otherwise have disappeared. The most widely used solutions to the problem are mainly based on the involvement of local communities, the restoration of valuable traditional practices and the revaluation of the role of rural communities in order to avoid land degradation. In addition, while in the past there was a tendency to look for solutions to primarily technical, today we tend to deal with the global nature of the problem, often closely associated with the continuous population growth, as well as socio-economic and political factors.


The erosion always acts in a selective manner. For example, the broken slope that can be observed in many forms of terrestrial survey, often lead to differences in hardness of the rocks. However, these breaks of slope are more or less pronounced depending on the local climate, in fact considerable differences can be observed in forms modelled in the same types of rocks, but under different climatic conditions. The weather can also promote the work of certain exogenous agents than others. The geological and climatic conditions affect the forms of relief, and determine the rate of erosion. The weathering degrade the splitting of rocks with rock elements and their chemical alteration. These degradation products add organic matter resulting from the decomposition of plants, the action of microorganisms is exerted on them, and led to the ground. But the soil is exposed to the erosive action of atmospheric agents (wind and rain). When the speed of wear of the soil is slow, its reformation for decomposition of rocks compensates the losses and the soil is maintained. But a breakdown of this balance in favour of the erosive action, accelerates the phenomenon. The accelerated erosion in rocks with little resistance break them down quickly and dig without being able to have the complete formation of a soil. But it is especially the abundance of precipitation, the effect of gravity in regions of strong gradients with increasing the speed of runoff, which causes the removal of rocky elements also large. It then reaches the maximum intensity if these factors is the lack of protection the defective plant or agricultural use of the land.


Accelerated erosion: badlands

In these conditions, the wear rate exceeds that of formation, soil thins and disappears, and the ground undergoes a catastrophic erosion with destruction of huge tracts of land. The accelerated erosion is extensive in the Mediterranean regions, in some areas there is a real desertification, which is an irreversible process that leads to loss of soil fertility, as a result of repeated destructive interventions operated by man, such as land reclamation and fire. There are numerous technical means used to protect the soil against erosion and accelerated, depending on the geolithological, climatic, soil and vegetation of the region concerned. Very little you can do instead of desertification if this process has already occurred, as happens every year where the climate is hot, dry and subarid; here the ecological degradation is now a fait accompli, as shown by the lack of vegetative growth after decades. All that remains is to totally avoid human intervention responsible for the spread of the phenomenon.


  • Stocking densities higher than the pasture can support
  • Trampling the grass of the pastures by animals
  • Over-exploitation of grazing land
  • Over-exploitation of agricultural land
  • Misuse of irrigation systems
  • Growing phenomenon of deforestation Impoverished land
  • Salinisation of soils
  • Exhaustion of reserves of mineral salts
  • Exposure to weather forecasters
  • Erosion

See Also

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