Transcript desertification

KHARTOUM
J
F
M
A
M
J
O
N
D
C
14
17
18
21
25 30 35 34 28 19
18
15
mm
5
6
-
-
8
17
9
10
J
-
A
-
S
11
13
• A desert is an area of land where
temperatures are hot and there is
very little rainfall. These are known
as hot deserts. Cold desert areas
such as the Tundra are areas where
rainfall is low and temperatures are
very cold.
• In any desert rainfall is always less
than 250mm per annum. In hot
deserts temperatures can reach as
high as 50C and minimum
temperatures can fall below 10C,
therefore similar to cold deserts,
there is a large range of temperature.
Temperatures during the day are hot
but at night all the heat escapes into
the atmosphere because there are no
clouds to trap the heat.
• Few plants can survive in hot deserts other
than XEROPHYTES. Xerophytic plants
have adapted to the lack of moisture by
having very small leaves (to reduce
transpiration), long tap roots (to reach for
ground water) and succulent tissue (to
store moisture). Other plants have
adapted in other ways.
• The cactus stores
water in its tissues.
Its leaves are small
and spiky which
reduces water loss
and of course
deters animals.
• Tumbleweed pulls
up its roots so that
it can be blown to
wetter desert
regions
• Date Palms are generally
found around oases. They
have tap roots which obtain
water from groundwater
and are very useful to
desert people (leaves can
be made into baskets,
young leaves can be eaten
by animals, dates can be
consumed and the tree
provides shade
• Some plants can lie
dormant in drought
conditions but as
soon as the
rainfalls they can
grow and bloom in a
matter of days
• Desertification is occurring in many
countries of the world but is most
noticeable in the Sahel zone which is
south of the Sahara desert. The
Sahel has a higher population than
the desert because the climate is not
as severe. Increasing population has
put too much pressure on the land.
1. Area of farmland
supporting a large
population
6. Land becomes
desert-like and
because soil has
been removed, it is
no longer farmable.
7. Population will
starve so many
leave the land to go
to the cities.
2. Area is
deforested and
cultivated without
periods of fallow
or use of
fertiliser. Cattle
DESERTIFICATION overgraze the
5. Heavy rains
land
or strong winds
will blow the
soil away as
3. Soil begins to lose
there is no
its fertility and
vegetation
becomes exhausted
binding soil
through overuse
4. Soil is left bare of
together
vegetation and
nothing will grow
• In Burkina Faso stone walls have been
built along contours to act as dams to
hold back soil and water run-off.
This has been very effective
resulting in thousands of hectare of
land being reclaimed. It is a cheap
solution which does not require the
use of expensive equipment.
• Reforestation of land that was
previously forested can be a very
effective way to halt the spread of
deserts. Tree planting is easily done
and is relatively inexpensive. The
only problem is the length of time it
takes for trees to mature and
therefore be beneficial to an area.
It is very much a long-term solution.
•
• Overcrowding has contributed to
desertification. Governments could reduce
population numbers by encouraging the use
of family planning to limit family sizes.
This is also a long term solution and has
not, as yet, been very effective. Many
people in Sahel countries want large
families as the children can work from an
early age and can support their parents in
old age. It is still an important part of the
culture to have large families – this can
take a long time to change.
• Educating people about the reasons why
desertification happens and the ways it can
be reduced is believed to be very
important. Farmers could be told about
the need to have periods of fallow on their
land to prevent overcultivation.
Pastoralists could be educated about the
need to limit herd sizes to prevent
overgrazing. If people understand what is
causing the problems, they are more likely
to take a proactive approach to help reduce
the problems.