4.1 INTRODUCTION

4.1.1 DESERTIFICATION: A MAN-MADE PHENOMENON

During the most recent period in the geological history of the earth, changing climate has dramatically transformed the landscapes of its more arid areas. For example in Australia some 20 000 years BP, much of the continent underwent a drying phase with lowered precipitation, prolonged droughts, and higher wind speeds. As a result the extensive dune fields of the core of the continent were rejuvenated (Bowler and Wasson, 1984), the vegetation became more sparse, species composition changed, and some plants and animals became extinct (Kershaw, 1984; Hope, 1984). Similarly, in Africa, there is evidence that, between 9500 years and 4500 years BP, savannahs and grasslands flourished in what is the now the hyper-arid deserts of the eastern Sahara (Ritchie and Haynes, 1987).

   Throughout these times, in both locations, modern man inhabited the landscape, experiencing dramatic ecological changes that must have moulded the nature of dependency on the land and the cultural heritage that recorded and perpetuated it.

   Desertification is the converse of this process. Man, rather than climate, generates the changes in the landscape. Desertification is the transformation of a landscape from one that did not resemble a desert to one that does. Short-term climate fluctuations, droughts, have usually been associated with the desertification process. However, the evidence supports the argument that the role of climate in desertification is catalytic rather than causal. Desertification is man-made!