Implementing Satellite-Based Grazing Gradient Methods for Rangeland Assessment in South Australia.

Abstract

This paper reports on a project to adapt grazing gradient methods, which use satellite data, to assess the condition of the northern rangelands of South Australia. Within this region, cattle graze in large paddocks on mainly ephemeral vegetation that responds in often unpredictable ways to erratic rainfall. Two methods were tested: one calculates average cover levels at increasing distance from watering points while the other produces a map showing where vegetation response to rainfall is different to that which might be expected. Before using the methods, it was necessary to rapidly produce a map of landscape types reflecting grazing preference and we show how this was obtained from classified satellite data. It was not possible to derive an accurate index of vegetation cover from the satellite data for areas with a dark stone mantle and these areas were excluded from grazing gradient analyses. We describe how analysis software was adapted to the needs of a client (SA Department of Environment and Natural Resources) and how training was provided. Testing of the grazing gradient technology as a suitable method for determining lease condition in northern South Australia is continuing and is supported by both pastoralists in the region and the Pastoral Board. Key words: land condition, pastoral lease assessment, satellite data, thematic mapper, grazing gradients, technology transfer