Declines in vegetation patches, plant diversity, and grasshopper diversitynear cattle watering-points in Victoria River District, northern Australia.

In this study, we quantify the density, cover and obstruction width of vege tation 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. Fou rteen study sites were located in the Victoria River District of northern A ustralia, 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 cra cking-clay black soils. At each study site transect lines were oriented wit hin the landscape to run downslope (i.e. in the direction of flows of run-o ff). We measured the intercept length and obstruction width of perennial ve getation patches along these lines. Plant diversity was measured in quadrat s positioned along each line and grasshopper diversity was determined by sp ecies 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 i ncrease time for water infiltration and soil-water storage. Surface roughne ss declined near water, as did the density, cover and obstruction width of perennial vegetation patches. Grasshopper and plant species richness also d eclined near water. These declines suggest strong linkages between landscap e function, biodiversity and impacts of cattle grazing and trampling. Cattl e 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.