Preface 
This volume sets down the efforts of scientists from 17 coun- 
tries and from as many disciplines to assess the state of man’s 
struggle to make productive and stable use of the world’s arid 
lands. Areas of meager and undependable rainfall and of sparse 
vegetation commonly called ‘“‘arid” account for roughly one-third 
of the land surface of the globe. Except where water is imported 
for irrigation, as down the Nile and Colorado rivers, most of that 
arid zone is sparsely settled and man lives in delicate adjustment 
to uncertain moisture and shallow soils. Unlike the other great 
land areas of low population density—the cold lands—the arid 
lands have been greatly affected by man’s use and misuse, and the 
margins of grazing, cropping and non-agricultural activity are 
shifting, unstable frontiers of occupance. 
The future of that occupance hinges in part upon success in 
maintaining the present resources base at present levels of living: 
range deterioration, water exhaustion, salt accumulation and 
accelerated erosion are among the hazards to permanent use. The 
future also hinges upon ingenuity in finding new and improved 
ways of increasing the usefulness of these great physical expanses: 
possibilities range from radical innovations in finding new water 
sources to patient application of principles known centuries ago. 
The whole range of thinking is recorded here without attempt- 
ing to reconcile differences of view or to fill obvious gaps. No 
single, clear answer emerges. Troublesome questions are identified 
and new avenues of attack are plotted. The individual papers and 
the group recommendations may be considered guideposts to 
scientific development in at least three ways. They mark a promis- 
ing method of collaboration across both national and disciplinary 
boundaries. They point out specific areas of research in which 
more vigorous activity isneeded. They suggest methods of think- 
ing about the future that may play a significant role in shaping 
that future. 
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