Desertification
Desertification is the spread of desert-like conditions in arid and
semi-arid areas, due to human influence and/or climatic change. Some of the
natural causes of desertification are wind erosion, climatic conditions,
and scarce water supply. There is a grave difference between areas where
vegetation has been retained and surrounding vegetation. For example,
"Nefta in southern Tunisia, the coverage of vegetation inside an area
fenced 60 years ago is 85%, in contrast to 5% outside the area."
Approximately one-third of the earth's land surface is semi-arid or arid.
This is the land where desertification occurs; not in any of the natural
desert zones. "Were these lands to continue to support agriculture, their
output could be worth at least $20 billion a year...the expense of
rehabilitating the degraded lands, and of halting the spread of deserts,
need no more than $2.5 billion a year." Even though the governments refuse
to put money into the fight against desertification there is still hope
through many agricultural foundations that aid poorer countries. If this
money is used wisely then the causes of desertification may be stopped.
Desertification is caused not only by nature but also by human factors
(over-grazing, poor irrigation, deforestation, and over-cultivation) all of
which are preventable.
Livestock, in many continents, overgrazes and flattens vegetation. Arid
areas, such as the Sahel ("Desertification was brought to the world's
attention by the Sahel disaster..."), the dry plains of India, and semi
deserts of Turkey can usually support a small number of people and their
livestock without permanent damage. The land often recovers when the
animals move on but when there are too many sheep, goats, and cattle
everything is eaten (including twigs and bark). When rain finally does fall
it is too late; trees, shrubs, and grass are all dead. Parts of North and
Central America, and most of Australia is at the risk of desertification
due to inadequate stock raising techniques (see map). This factor, which is
a main cause of desertification, is preventable. Disease-resistant
varieties of animals (can survive drought and eat little) should be kept by
farmers in marginal lands. "They cause less harm to the environment than do
more exotic breeds." Another strategy is to make laws on the periods of
grazing. This will give over-worked pastures time to recover. The final
method I would suggest is to plant vegetation which helps to restore soil
fertility. "Legume grasses, such as clover and alfalfa," are suggested in
GAIA, An Atlas Of Planet Management.
Improper irrigation sterilizes the earth with salts and alkalis. Canal
irrigation is the method used in many poorer countries to supply the crops
with water. Much of northern and southern Africa is at high risk of
desertification because of this and other poor irrigation techniques (see
map). Better use of the scarce water available in these countries must be
practiced. Drip or sprinkler irrigation should be used in place of canals.
"This method (sprinkler) reduces water losses by evaporation and to weed
growth along ditch-banks." By converting to the sprinkler method the soil
will increase its fertility and crops will prosper. In addition to this,
fertilizers and pesticides should be combined with the water since it will
be cheaper in the long run. Drip irrigation is where the water is directly
put on the crops. This wastes little water since the water is not used by
weeds. By improving the irrigation in many areas this helps to halt the
desertification process.
Deforestation is causing desertification when people harvest trees and
woody plants for fuel. In many of these regions there is a huge number of
people whose only source of fuel for heating their homes and cooking their
food is wood. Once all the available dead wood has been collected, , trees
are cut down. Consequently, there is nothing to protect the soil. It
turns to dust and is soon washed away or blown away by the wind. Places
such as Kenya are at high risk of becoming desert due to this destruction
of trees (see map). In order to prevent this, many trees, such as the
leucaena, should be planted. These trees are excellent for use as fuel
since they "grow swiftly...and because they fix their own nitrogen, help to
restore soil fertility." If these type of trees were planted the worry of
an encroaching desert would lessen since trees would always be available to
chop for firewood.
Over-cultivation occurs when many marginal lands are cleared and
ploughed in farming attempts. Too many farmers are drifting into marginal
lands and rob the land of the little richness it has to offer. There
should be an intensified use of the good land. Crops should be grown in
rapid succession and perhaps multicropping should be practiced (a method
where more than one crop is produced on the same land). By improving
irrigation (previously mentioned) the good land can also be put to better
use. Marginal lands should produce crops which can prosper without long
periods of rain. These crops include, "millet, sorghum, amaranth, certain
beans, and fast maturing maize". Almost half of Asia is at high risk and
one-third is at moderate risk of desertification (see map). If the proper
steps were taken to utilize the full potential of rich quality land and the
poor quality land were allowed to replenish itself, then the
desertification process would slow down dramatically.
Desertification is caused by a combination of natural and human
factors. If steps are not soon taken by many countries they may find their
people starving to death in large numbers. Over-grazing is a major cause
of desertification and can be stopped by keeping genetically advanced
species of animals which eat less vegetation. Poor irrigation (another
human cause) should be corrected by converting from canal to sprinkler or
drip irrigation which will put the small amounts of water available to
better use. Deforestation is obviously caused by humans and can be slowed
or lessened by planting trees which grow quickly in large numbers (leucaena
trees). Finally, the over-cultivation of marginal lands is a man made
cause of desertification. This can be stopped by putting good land to
greater use, therefore allowing the poor land to recover. The earth, as a
whole, will suffer if the human causes of deforestation are not eliminated.
BIBLIOGRAPHY
1. Encyclopedia Britannica. Deserts. Chicago: William Benton., 1981.
2. George, Uwe. In The Deserts Of This Earth. New York: Harcourt Brace
J ovanovich Inc.,1977.
3. McGraw-Hill Encyclopedia Of Science And Technology.
Desertification.New York: McGraw-Hill Inc., 1982.
4. Molyneux, John, and Marilyn Mackenzie. World Prospects. Ontario:
Prentice-Hall Canada Inc., 1987.
5. Myers, Dr. Norman. GAIA An Atlas Of Planet Management. New York:
Anchor Press, 1984.
6. Seager, Joni. The State Of The Earth Atlas. Toronto: Simon and
Schuster Inc., 1990.
ENDNOTES
McGraw-Hill Encyclopedia Of Science And Technology, Desertification
(New York: McGraw-Hill Inc., 1982) 126.
Dr. Norman Myers, GAIA An Atlas Of Planet Management (New York: Anchor
Press, 1984) 46.
Myers 47.
Myers 59.
Myers 59.
John Molyneux, and Marilyn Mackenzie, World Prospects
(Ontario: Prentice-Hall Canada Inc., 1987) 94.
Myers 59.
Myers 59.
Joni Seager, The State Of The Earth Atlas (Toronto: Simon And Schuster
Inc., 1990) 36, 37.