MODELING PATTERNS OF DEFOLIATION BY GRAZING ANIMALS IN RANGELANDS

1. This study describes techniques and models for identifying the dist ribution of grazing by domestic animals in large (> 100 km2) rangeland paddocks in arid central Australia. It also examines the relationship between grazing distribution and the characteristics of the vegetatio n cover. 2. Models of grazing distribution and resultant defoliation t hrough time use the inverse Gaussian distribution function. Additional model components describe the effects of natural decline in cover ove r time and the effect of past grazing on the spatial distribution of p alatable species. 3. Models are calibrated using remotely sensed veget ation cover data derived from Landsat MSS and closely reflect observed animal distributions. 4. Fitted models show systematic variations wit h observed plant species composition and the amount of forage present.