3
How does desertification
occur?
1.C3T1 2.C3T2
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C3M1
3. Mato Grosso in Brazil: extensive deforestation to the north of Cacères
© Yann Arthus-Bertrand Earth from Above / UNESCO

Over-exploitation of natural resources

Desertification is the accumulated result of ill-adapted land use and the effects of a harsh climate. Four human activities represent 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. Moreover, the lack of education and knowledge, the movement of refugees in the case of war, the unfavourable trade conditions of developing countries and other socio-economic and political factors enhance the effects of desertification. The causes are multiple and interact in a complex manner.

Due to the lack of alternative survival strategies, farmers tend to relentlessly exploit natural resources (food crops, water for drinking and washing, firewood) to the point that they are often over-exploited and cannot regenerate naturally. Soil nutrients and organic matter begin to diminish as intensive agriculture removes quantities of nutrients greater than the soil’s natural regeneration capacities. As a consequence, the soil is unable to recover, as it does during fallow periods, resulting is an ever-increasing spiral of environmental degradation and poverty, the principal causes of desertification.

The principal causes exacerbating land degradation derives from the farmers’ determination to maximize soil productivity, which include:

C3M2
4. Katiola in the Côte d’Ivoire: diamond mines or precious metal
open quarries are a cause of desertification. Large surfaces are
cleared and turned upside down hundreds of metres into the ground.
When the mines are then disaffected the environment is
totally destroyed rendering land rehabilitation almost impossible.
© Yann Arthus-Bertrand / Earth from Above / UNESCO

Deforestation and energy

C3M3
5. Deforestation is a major cause of desertification.
In dry tropical zones, wood is the principal source
of domestic energy and is also used in construction.
In this way, large tracts of forest are destroyed. In the
drylands, forest regeneration is very slow because of
water scarcity.
© UNESCO-MAB

The use of firewood is one of the principal causes of desertification. In tropical arid areas, wood is the principal source of domestic energy for cooking and lighting both in rural and urban populations.
In order to limit the need for deforestation, only renewable sources of energy
(hydraulic, wind, solar) and gas and petrol should be encouraged as it can replace wood consumption.
Due to the lack of water in the drylands, forest regeneration is very slow, reducing the dynamic growth of vegetation. However, allowing for rest periods from grazing and increasing fallow periods, generally have spectacular regenerating effects on the forest.

Population growth

Since the middle of the 20th century many countries have experienced significant population growth (a greater number of children are born while infant mortality decreases slightly, but also people tend to live longer). As a result, the rate of population growth is often high: between 2% and 3% a year, meaning that in certain countries, the population will double within the next 20 to 30 years and with it, a growing population to feed. The ensuing increase in agricultural pressure on land, with the added effect that the soil in the drylands is not given sufficient time to recover, leads to an eventual drop in productivity. Paradoxally, human intervention is required to regenerate degraded lands. People have both the ability to destroy the land and the capacity to restore and rehabilitate their environment.

activities

pencil

Ask your grandparents how many inhabitants there were in your village/town when they were your age. Find out how many people live in your village/town today.

On a piece of graph paper, draw a graph with the years shown along the horizontal axis and the size of the population shown along the vertical axis.

Show the evolution of the population in your village/town on the graph (See diagram).
Has the population increased or decreased? Why?

What are the environmental and economical consequences in your region?

C3M4

smile

Calculate the average number of children per family in your class.

Is the number more or less than the average number of children observed in your grandparents’ generation?

What do you think are the reasons for the rise or fall of the population?

pencil

Ask your grandparents if there are more or less trees in your area today compared to the number of trees
when they were your age.

Are deforestation activities taking place in your region? If so, why?

Is the wood needed for providing energy?

Are wooded areas cleared
for agriculture?

In your view, what should be done to halt these activities?

Are there any alternatives?


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