ABSTRACT
From ancient times to the present, humans have tried to utilize the arid lands of the world with only marginal success. We have been more successful in our attempts to utilize semiarid lands. However. heavy and! or prolonged use of semiarid lands has often led to a reduction in available moisture for vegetation and has initiated succession from semiarid types of vegetation toward arid types of vegetation. Such human-caused succession of vegetation from semiarid to arid or from arid to extremely arid is currently referred to as desertification. Le Houerou (1986) used the term "desertization" for this process in northern Africa and emphasized that the process is caused by human beings. not climate.
