With accuracy everybody has seen the pictures of human beings nothing but skin and bones, too weak to walk, using their last reserves of power to get some food in the news before. Most of these shocking pictures come from drylands. To put it more precisely from arid and semi-arid areas especially on the African continent. Beneath wars, droughts, underdevelopment and poverty the apparent invisible process of growing deserts is one reason for such horrible pictures. But the growth of deserts is not only an African or only a Third World problem. You can also "notice" it in other areas like for example in the Great Plains and the Middle East. This is the reason why we inevitably have to ask the question if desertification is only a central problem for desert-near areas.
Through a short clarification of one`s term followed by a detailed specification of causes and consequences of desertification and a concluding attempt to give a slight image of possibilities of solutions, preventions and after-care I will try to answer the question and show the reader the connection of human actions, natural influences and desertification.
In my expositions I mainly followed the work of Nick Middelton because it explains shortly but comprehensible a complex process and gives a good view about the main causes and consequences of desertification.
Content
1. Introduction
2. What is desertification?
3. The cause of desertification
3.1. Human activities
3.1.1. Overgrazing
3.1.2. Overcultivation
3.1.3. Vegetation clearance and deforestation
3.1.4. Salinization
3.2. Natural factors
3.2.1.Drought
3.2.2.Climatic influences
4. Consequences of desertification
4.1. Effects on society
4.1.1. Migration
4.1.2. Traditional responses and preparation
4.1.3. Famine
4.2. Feedback mechanisms
4.2.1. Albedo change
4.2.2. Atmospheric dust
5. Case Study
6. Conclusion
Bibliography
1. Introduction
With accuracy everybody has seen the pictures of human beings nothing but skin and bones, too weak to walk, using their last reserves of power to get some food in the news before. Most of these shocking pictures come from drylands. To put it more precisely from arid and semi-arid areas especially on the African continent. Beneath wars, droughts, underdevelopment and poverty the apparent invisible process of growing deserts is one reason for such horrible pictures. But the growth of deserts is not only an African or only a Third World problem. You can also "notice" it in other areas like for example in the Great Plains and the Middle East. This is the reason why we inevitably have to ask the question if desertification is only a central problem for desert-near areas.
Through a short clarification of one`s term followed by a detailed specification of causes and consequences of desertification and a concluding attempt to give a slight image of possibilities of solutions, preventions and after-care I will try to answer the question and show the reader the connection of human actions, natural influences and desertification.
In my expositions I mainly followed the work of Nick Middelton because it explains shortly but comprehensible a complex process and gives a good view about the main causes and consequences of desertification.
2. What is desertification?
This chapter can not give the final answer what desertification exactly means because it is the "name for a very complicated subject"[1]. Because of this I want to give a definition of the word itself. It comes from the Latin words "desertus facere" which can be translated as "making deserts" with emphasis on the word "making"[2]. You can also say "man-made deserts" which implicates anthropogenic influences on the process of desertification. So we can shortly say desertification is a special kind of land degredation which causes desert like conditions. On the one hand it is influenced by human actions and on the other hand by natural factors especially climatic factors.
In fact it is rather difficult to find a common definition for desertification because the scientists have different comprehensions of the word. For this reason I want to stick with the introduced definition. I hope while reading the executions everybody will be able to picture it to himself what desertification is and what the reasons for this process are. What I want to emphasize is that it is a complex process and that it is dangerous to reduce it on only one aspect through a one dimensional view. Altogether we can say desertification is a process under definite climatic conditions especially in inhabited arid, semi-arid and subhumid ecosystems with degredation of the ecosystem, reduction of productivity, alteration in the biomass and diversity of life forms[3].
The word desertification became a widely used term after the drought catastrophe in the African Sahel region in the 70's. The events caused the United Nations to hold a conference on desertification (UNCOD) in Nairobi in 1977[4]. A lot of industrial countries and nearly all developing countries especially those of the affected tropical and subtropical areas joined the conference. That shows that desertification is a global problem and that it could affect a lot of areas even in Europe.
illustration not visible in this excerpt
Fig.1: Distribution of hyperarid, arid semiarid and subhumid lands: (http://www.dreieich schule.de/erdkunde/wueste_8/index_n.htm )
3. The causes of desertification
As I have pointed out there are two main reasons that are responsible for desertification. On the one hand human activities that affect the labile ecosystems through stressing them too much and on the other hand natural factors (climatic factors) that means among other things occuring processes strenghten by ecological destruction.
3.1 Human activities
When we talk about human activities in connection with desertification we will always meet the word "overuse". In other words methods of land use that have been employed to intensively[5]. There are a few reasons for too intensive cultivation or herding.
For example an area is experiencing drought while the less or labile vegetation layer caused by the lack of water is exposed to the same grade of use. The driving force behind overintensive land use is the increasing demand for food because of population growth especially in the developing countries[6]. To comply with this demand the countries try to increase their yields through new and more intensive technologies with the consequence that the ground could be sustainably damaged for example through soil compression. But also monocultures for cash-crops and using land that is not well-suited to agricultural use stresses the ecosystem dryland. So the ecosystems in these "overused areas" have less or no time to recover and mostly they are irreversible destroyed. In the following I will have a detailed look at the most important human activities affecting drylands.
3.1.1. Overgrazing
Grazing land in "critical areas" has a low carrying capacity. That means to a certain point it is possible to use the land without loss of quality. But when you cross this carrying capacity trough overgrazing it has consequences for the vegetation and the soil.
The quality and quantity of vegetation can be implicated. The vegetation layer becomes thinner so that the soil is exposed to erosion through wind and water especially in rain seasons because of the reduced root-system. Also the hooves of grazing animals support the effect of erosion through compressing the soil and destroying the weak vegetation. Especially around wells as a meeting place overgrazing is a problem as the illustration shows.
But also political and cultural aspects have an influence on overgrazing. In fact "the size of a person's herd reflects its social status"[7] and in times of good rainfall the herds grow what causes pressure of land use during dry seasons or droughts. Another aspect is that governments try to "control and tax their population"[8] or search soldiers for their armies. They make efforts to settle down the traditional wandering nomads what often results in overgrazing and stressing the same area the whole year.
3.1.2. Overcultivation
Another human action that leads to desertification is overcultivation. It can take a number of forms. Overcultivation means that a farmer shortens the period of cultivation because more food is needed or it may mean that not suitable areas are cultivated. For example "cropping now takes place in areas receiving a little as 150mm of annual rainfall in North Africa and the New East and 250mm in the Sahel. Under such conditions crop expectance is very low [...]"[9].
There are several reasons for overcultivation. In the past farmers pursueded shifting cultivation, that means they moved on to plant other areas while the previously cultivated areas lied fallow and had the possibility to recover. But through the growth of population, the incidental increasing demand for food and the production of cash crops the traditional methods of cultivation changed so that "fallow periods are shortened"[10]. The production of cash crops for export leads to the use of more intensive technologies and fertilizers and through the spreading cash crop production the traditional forms of cultivation are pushed into so-called marginal areas. The effects of overcultivation on soil are reduced soil fertility and plant growth. Like through overgrazing the soil is now exposed to wind and water erosion and especially the "nutrient-rich upper layers go first"[11]. Also, overcultivation as a human action causes desertification.
[...]
[1] Middelton, 1991, p.5
[2] Mensching G., 1990, p.1
[3] Mainguet, 1991, p.2
[4] Middelton, 1991, p.5
[5] Middelton, 1991, p.13
[6] ibid, p.14
[7] Middelton, 1991, p.16
[8] Middelton, 1991, p. 16
[9] Glantz, 1977, p.26
[10] Middelton, 1991, p.16
[11] ibid
- Quote paper
- Dipl.-Geograph/European Master in International Humanitarian Action Chris Hartmann (Author), 1999, Desertification - Only a central problem for desert-near areas?, Munich, GRIN Verlag, https://www.grin.com/document/46476
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