The Role of Nutrient Gradients in the Vegetation Zonation around Sheep Camps on the Northern Tablelands of N.S.W.

Abstract

The relationships between nutrient gradients and field species zonation surrounding sheep camps in natural pastures on the Northern Tablelands of N.S.W. were investigated. Soil analyses of the selected field sites at 'Balala' station, 20 km west of Uralla, continued the presence of nutrient gradients. Nutrients were present in high concentrations on the sheep camp, dropping sharply within a short distance of the camps and reaching the lowest levels in the paddock extremity soils. Physiological responses of a broad range of native and naturalised grass species present in pastures of the Northern Tablelands indicated that the important nutrients were nitrogen, phosphorus and sulphur. The native and naturalised grasses studied, all displayed a unique response to different soil types and varying levels of nitrogen, phosphorus and sulphur applications. The cool season annuals, which dominate the sheep camps, produced the highest yields in the sheep camp soils... Floristic analyses of the field sites revealed a distinct species zonation. The species generally appear to be classified into one of four groupings, namely, those dominating the sheep camps, those found only in the paddock extremity sites, those confined to the area between the sheep camp and the paddock extremity, i.e., the sheep camp margins, and those species displaying a ubiquitous distribution, being present across all three site types mentioned previously.