Assessing and monitoring desertification with soil indicators

A stepwise monitoring procedure based on the Trigger-Transfer-Reserve-Pulse framework of landscape function determination is proposed as a method to assess desertification in rangelands. The procedure is entirely field-based, using indicators of surface processes to infer the status of landscape on a function/dysfunction continuum. The first step is to identify, map and measure zones of resource loss (run-off) and resource gain (run-on) in the landscape. In the second step, each zone type is assessed, using 11 soil surface indicators reflecting the effect of surface processes on soil as plant habitat. The indicators are grouped into three indices; stability (manifest as resistance to erosion), infiltration/water storage and nutrient cycling. Trends over time, or in response to specific environmental events can be plotted. A framework for the interpretation of the data is suggested to assist management decisions. The method facilitates the distinction between mere utilisation of pasture resources and desertification, which by our definition is loss of function. The method is repeatable and consistent between observers. The approach was derived from a wide range of Australian rangelands and has been tested in South Africa and USA for broad application. Recent use to assess minesite rehabilitation shows that the approach can accommodate a very wide range of function/dysfunction scenarios.