Natural resources and development in Arid regions

Almost one third of our planet is made up of zones. with varying degrees of aridity. The origin, structure and dynamics of the arid systems are as diverse as the effects of man's activities upon these systems. These arid systems are shared by around 50 countries, forming a colourful mosaic of social, economic and environmental situations. Consequently, the development policies and the strategies for the utilization of natural resources present a wide range of manifestations. In some developed countries, such as the USA and the Soviet Union, arid zones constitute only a small part of their vast terri tory and their level of economic development permits the carrying out of large, well-organized resource projects with a high science and technology content. Other coun tries are not so fortunate in many African countries their economic space completely coincides with intensely arid zones and their scarce social and economic resilience intensifies the effects of the sometimes dramatic droughts

in accelerated desertification processes. The dynamics of arid systems are the product and origin of the low availability of renewable resources - water, soil, flora and fauna - which leads to a low pri mary productivity of their ecosystems, or, in other words, a reduced capacity to fix, through basic biological mech anisms, the solar energy required for the organization of the ecosystem.