Degradation propensity in Australian land tenure systems

Abstract

Land degradation and its management have profound effects on environmental quality and sustainability. Given the diverse range of environmental conditions and land uses across Australia, it is not uncommon for land degradation to occur on many different tenure types. This paper presents an analysis of the relationships between soil physical and chemical limitations, different degradation types and their interactions with varying tenure classes. Three continental scale datasets were used in this analysis to analyse degradation propensity in Australian land tenure systems. The datasets comprised: The Australian Land Information Groups (AUSLIG) Land Tenure classification at a 1:5 million scale; the Commonwealth Scientific and Industrial Research Organisation (CSIRO)/Bureau of Resource Sciences (BRS) Soil Limitations for Agriculture classification at a 1:2 million scale; and a BRS classification of land degradation types and occurrence in Australia at a 1:20 million scale. The continental coverages were rasterized and summarized as a three-way contingency table of counts. The analysis of the three-way contingency table included: summary histograms; a non-parametric analysis of the cumulative empirical distribution functions; and the use of a generalized linear model (GLM). Over 60 per cent of the Australian continent is classified and used as agricultural land, which has a significant influence on the Australian environment. These agricultural lands are predominantly divided into two tenure types: freehold (20 per cent) and crown leasehold (42 per cent). The analysis indicates that although crown leasehold land has a large percentage of lands vulnerable to degradation, these lands are less degraded than the freehold lands, which have fewer soil physical and chemical limitations to agriculture. Copyright © 1999 John Wiley & Sons, Ltd.