Introduction

Land degradation is a complex phenomenon because there is a multitude of possible causes and effects, both onsite and off site. All human land usage affects the state of the land and its impact is critically influenced by nature's wheel of fortune which brings great variations in rainfall, wind, and temperature patterns. Much land degradation takes place during periods of extreme climatic conditions such as prolonged droughts, severe flooding and so forth. The natural rate of soil erosion in Australia is considered to be relatively low by world standards, but the potential for land usage to accelerate the rate of degradation is high (Olive 1983).

Land degradation problems stem mainly from agriculture and pastoralism which are the major uses of land. However, severe degradation problems are commonly caused by many other activities such as mining and engineering, commercial forestry and woodchipping, real estate development, and some recreational activities (eg off-road vehicles). Resulting damages include onsite loss of soil and nutrients, sedimentation of waterways, dryland salting, irrigation-induced salinisation, desertification, destruction of natural flora and fauna habitats, beach and sand dune drift and erosion, unaesthetic scarring of landscapes and spread of weeds. The costs of land degradation may be fully onsite or fully off site. However, it will most often result in a mix of both onsite and off site damages. Thus, it may be seen as a double-edged sword: productivity of the land is reduced and waterways and the air are commonly polluted.