干旱区生态环境知识资源中心

Commercial grazing is possible over much of and Australia due to a high density of artificial watering points. The broadscale supplementation of drinking water has not only enhanced densities of sheep (Ovies aries), cattle (Bos taurus, Bos indicus) and goats (Capra hircus), but has also contributed to increased populations of native kangaroos (Macropus spp.) since pre-European times. Empirical data are compiled to identify threshold distances from water containing 95% of a population of grazing animals. For sheep the proposed threshold is 3 km, 6 km for cattle and 7 km for red kangaroos. Despite clear evidence of waterfocussed grazing, evidence of decreased biodiversity in relation to distance to water is scant and conflicting between studies. Reasons for this include the limited power of sampling designs and further research is required to establish the value of water-remote areas as grazing-relief refuges and to demonstrate that the recovery of grazing sensitive species is achievable after grazing relief has been restored. An eastern Australian case study indicates that within some large areas used for commercial pastoralism, the density of wate:r points is such that there is nowhere further than 7 km from water. Where water-remote ar’!as persist, their maintenance should be paramount. In the context of rangeland pastoralism and high densities of water points, de-stocking and water-point closure over large areas will be the most effective means of achieving grazing relief and will require strategic land acquisition. (c) 2008 Elsevier Ltd. All rights reserved.