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Desertification
Discuss the issues raised by the cartoon.
What is its central point?
Who might have published it?
Sahelian Africa
Sahel: A semiarid region of north-central
Africa south of the Sahara Desert
Background to the Sahel
• The countries comprising sub-Saharan Africa depend
more on their natural resource base for economic and
social needs than any other region in the world.
• Two-thirds of sub-Saharan Africa's people live in rural
areas and rely on agriculture and other natural resources
for income.
• Environmental problems of sub-Saharan Africa include
air and water pollution, deforestation, loss of soil and soil
fertility, and a dramatic decline in biodiversity throughout
the region.
The Sahel regions are areas which experience
desertification.
Desertification is when a
desert gradually spreads
to the surrounding areas
of semi-desert.
Why?......
What is it ?
"...'desertification' means land degradation in arid, semi-arid and dry sub-humid areas
resulting from various factors, including climatic variations and human activities;
Why does the Sahel suffer from desertification?
DESERTIFICATION
Increase in cattle
Increase in population
Deforestation for fire wood
Grassland grazed more intensively
Roots no longer hold soil together
Roots may be eaten as well as grass
Leaves no longer protect soil from weather
Less vegetation means less protection
from weather
Loose top soil blown away by wind
Loose top soil blown away by wind
(Soil Erosion)
(Soil Erosion)
= DESERTIFICATION
=
Since the 1960s the Sahel has been afflicted
by prolonged periods of extensive drought.
The above plots are June through October averages of the Sahel rainfall
series. The averages are standardized such that the mean and standard
deviation of the series are 0 and 1, respectively, for the periods identified in
each plot. Sahel rainfall is characterized by year to year and decadal time
scale variability, with extended wet periods in 1905-09 and 1950-69, and
extended dry periods in 1910-14 and 1970-1997.
More than half of
Africa is now in
need of urgent
food assistance.
The UN's Food
and Agriculture
Organisation
(FAO) is warning
that 27 subSaharan countries
now need help.
BBC News 31st January 2006
How can population growth cause desertification ?
High Birth Rates
Increase in demand for
fuel wood.
Increase in population
More immigrants from
surrounding countries
affected by civil war.
Increasing pressure on the land.
Fuel wood needed for cooking
Villagers are forced to walk further to
collect wood.
More people working will increase
desertification
Farmers grow crops on the marginal land where
the land is most at risk from erosion.
Fields are not given a chance to recover.
(Soil Erosion)
Accelerated Rate of Desertification.
(Soil Erosion)
= DESERTIFICATION
=
How much is population growth to
blame?
• Sub-Saharan Africa has one of the world's
fastest growing populations (approximately
2.2% a year), and is expected to be home
to over a billion people by 2025.
• In recent years, population growth rates
have declined from 2.4% in 1997 to an
expected rate of less than 2% by 2006.
The problems in the Sahel..
• Only a small portion of the total land area of the Sahel is
suitable for ecologically and economically sound
agriculture.
•The ratio of inhabitants to available
agricultural land thus presents a
much darker picture than the low
population density might suggest.
• The highest population densities
relative to cultivable land are 633
people per sq km in Mauritania, 293
in Mali, and 228 in Burkina Faso. In
Senegal the rate is lowest at less than
100 people per sq km
Limiting
Desertification
In Niger in West Africa desertification has led to
increased food shortages in an area where food is
already scarce. One of the projects combating
desertification encourages farmers to plant edible,
drought-resistant perennial species that do not
need watering or fertilisers. The continued
presence of the plants throughout the season
prevents erosion of topsoil by wind.
Chinese workers dig a well to water
plants to protect a highway in the
Taklimakan Desert, the world's second
largest moving desert. Planting tree
belts, building sand fences and
covering dunes with grids of straw and
spraying dunes with petrol are some of
the ways people are combating
desertification. According to Chinese
research the speed of desertification in
the Taklimakan area has decreased by
50% in the past 10 years.
The Results of desertification
Soil looses its protective cover,
contains less humus and holds
less moisture.
As the soil becomes exposed to the
wind it becomes increasingly at risk
from erosion.
Desertification is avoidable with the
following actions:
Terracing any slopes to reduce run off and
increase soil moisture.
Less Intensive use of the land. Let it recover
and have fallow time before using the land
again.
Desertification is avoidable with the
following actions:
Planting tress that are good for building
materials and fruit.
Planting hedges around fields to stop
wind blowing the soil away.
Desertification is avoidable with the
following actions:
Using branches for fuel not whole trees.
Allow the land to fallow.
What about the role of
governments?
• Some three million people are going hungry in
Zimbabwe, which used to be the region's bread basket.
Most donors say the government's seizure of productive,
white-owned farms has worsened the effects of poor
rains.
• The government has also been accused of only
delivering food aid to its own supporters and punishing
areas which vote for the opposition.
• Conflict obviously makes farming difficult, as people
either run away from their fields or are too afraid to
venture too far from their homes.
• Farmers and pastoralists in countries such as Somalia
and Democratic Republic of Congo face constant
harassment by armed men.
What can be done?
• Immediate deliveries of food aid will obviously stop
people starving but are not a long-term solution.
• Economists say that modernising agriculture is the best
way forward, so farmers use more efficient techniques,
such as irrigation.
• Some say the key would be to give farmers title-deeds to
their land, so they could use it as collateral to borrow
money to invest.
• In many countries, rural land is held on trust by tribal
chiefs and handed out to individual families.
• But changing systems such as this would take many
years to take hold in more remote areas, where people's
lives have hardly changed for hundreds of years.
Read the worksheet you have been given and then answer
these questions:
1. What are the causes of desertification ?
2. What does population have to do with
desertification ?
3. How is the population affecting the Sahel ?
1.
Getting in a spin over desertification.
1 = Causes of
desertification.
2.Effects of Desertification/
Cut out the spiral and
Then write down the solutions on the
back.
2.