In this study, we quantify the density, cover and obstruction width of vegetation patches, the roughness of landscape surfaces, and the diversities of plants and grasshoppers with distance from cattle watering- points. We used distance from water as a surrogate for a gradient in grazing pressure. Fourteen study sites were located in the Victoria River District of northern Australia, seven from a water point on Kidman Springs Station on calcareous red loam soils and seven from a water point at Mount Sanford Station on craclcing-clay black soils. At each study site transect lines were oriented within the landscape to run downslope (i.e. in the direction of flows of run-off). We measured the intercept length and obstruction width of perennial vegetation patches along these lines. Plant diversity was measured in quadrats positioned along each line and grasshopper diversity was determined by species counts on each site. We also surveyed the roughness of the landscape surface along each line. A rough surface will tend to slow run-off. hence increase time for water infiltration and soil-water storage. Surface roughness declined near water, as did the density, cover and obstruction width of perennial vegetation patches. Grasshopper and plant species richness also declined near water. These declines suggest strong linkages between landscape filmtion. biodiversity and inipacts of cattle grazing and trampling. Cattle will always create 'sacrifice zones' around watering-points. However, the area of this impact on function and diversity can be minimised by managing the timing and intensity of paddock use. Key words: grazing gradients. Kidman Springs, landscape function. Mount Sanford, piosphere, surface roughness, tropical grasslands, tropical savannas

The logistic growth curve equation of population biology is shown to satisfactorily describe the responses of some vegetation and soil measures as a function of distance out from a watering point. Two of the three parameters of this equation can be readily related to parameters of the herbivore - rangeland ecosystem. The potential use of this equation is explored for the development of a simple, quantitative range assessment method. -

SHRUBKILL is a microcomputer based decision-support system which provides expert advice on the use of fie to control non-desirable shrubs and thus improve grazing potential in the semi-arid woodlands of eastem Australia. Pescribed fire is argued to be the only economically viable management option for broad-scale shrub control in these rangelands. Management decisions about "when" and "how" to bum and the cost and expected economic benefit of buming involve answering many difficult questions which can be aided by the advice of experts. However, these experts are not always available to give on-the-spot advice to managers. SHRUBKILL is a decision-support system that has incorporated the knowledge of fire-experts in an easy-to-use microcomputer program to: advise the user on what the "expert" would have recommended; provide detailed information supporting the expert's recommendation; and give summaries of the consultation. SHRUBKILL was written in BASIC on an IBM Personal Computer but it will run on IBMPC compatibles.

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