Three-quarters of the Australian continent is arid or semi-arid. History has shown that man{u2019}s utilisation of arid lands has, in general, caused progressive deterioration of the natural vegetation, the animal resources, and finally the landscape itself. Already settlement in Australia{u2019}s arid lands bears all too evident witness to damage and degradation. Each additional use of these lands - for grazing, farming, mining - tends to distort the extremely delicate ecological balance of most of Australia.