Page 167 - Encyclopedia Of World History

desertification 517

reported desertization northwards and southwards from
the Sahara could not be explained by a general trend
towards drier climate during this century” (Rapp 1974,
29).
Woodcutting is a serious cause of vegetation decline
around almost all towns of the area to the south of the
Sahara. Many people depend on wood for domestic
uses, and the collection of wood for charcoal and fire-
wood is especially serious in the vicinity of large urban
centers. Likewise, the recent drilling of wells has enabled
rapid multiplication of domestic livestock numbers and
large-scale destruction of the vegetation in a radius of 15–
An abundant supply of water is pumped
30 kilometers around them. Given this localization of
from an artesian well in North Africa to
degradation, amelioration schemes such as local tree
irrigate the fields. Adequate irrigation in
planting may be partially effective, but ideas of planting
this arid region is an important factor in
massive belts as a cordon sanitaire (protective barrier)
buffalo breeding.
along the desert edge (whatever that is) would not halt
deterioration of the land beyond this belt.The deserts are
not invading from without; the land is deteriorating rainfall and to move away from regions that had become
from within. exhausted after a long period of use. As soon as migra-
Clearly, therefore, a combination of human activities tions are stopped and settlements imposed, such options
(e.g., deforestation, overgrazing, and plowing) with occa- are closed, and severe degradation occurs.
sional series of dry years largely leads to presently People have suggested not only that deserts are
observed desertification. The process also seems to be expanding because of human activity, but also that the
fiercest not in desert interiors, but rather on the less arid deserts themselves were created by human activity. Peo-
marginal areas around them.The combination of circum- ple have proposed, for example, that the Thar Desert of
stances particularly conducive to desert expansion can be northwest India is a postglacial and possibly a post-
found in semiarid and subhumid areas—where precipi- medieval creation, and Ehrlich and Ehrlich have sug-
tation is frequent and intense enough to cause rapid ero- gested that the vast Sahara Desert itself is largely human
sion of unprotected soils and where humans are prone to made.This proposal is not accurate.The Sahara, although
mistake short-term economic gains under temporarily it has fluctuated in extent, is many millions of years old,
favorable climatic conditions for long-term stability. predates human life, and is the result of its climatic
These tendencies toward bad land-use practices partly situation.
result from the imposition of state boundaries on many Possibly the most famous case of desertification asso-
traditional nomadic societies, restricting their migration ciated with soil erosion by deflation was the Dust Bowl
routes, or from schemes implemented to encourage the of the 1930s in the United States. In part the Dust Bowl
nomads to become sedentary. Some of their traditional was caused by a series of unusually hot, dry years that
grazing lands have been taken over by cash-crop farmers. depleted the vegetation cover and made the soils dry
The traditional ability to migrate enabled pastoral enough to be susceptible to wind erosion, but the effects
nomads and their stock to make flexible use of available of this drought were worsened by years of overgrazing,
resources according to season and yearly variations in poor farming techniques, and the rapid expansion of