Clearing of native vegetation is a major threat to biodiversity in Australia. In Queensland, clearing has resulted in extensive ecosystem transformation, especially in the more fertile parts of the landscape. In this paper, we examine Queensland, Australian and some overseas evidence of the impact of clearing and related fragmentation effects on terrestrial biota. The geographic focus is the semi-arid regions, although we recognise that coastal regions have been extensively cleared. The evidence reviewed here suggests that the reduction of remnant vegetation to 30% will result in the loss of 25–35% of vertebrate fauna, with the full impact not realised for another 50–100 years, or even longer. Less mobile, habitat specialists and rare species appear to be particularly at risk. We propose three broad principles for effective biodiversity conservation in Queensland: (i) regional native vegetation retention thresholds of 50%; (ii) regional ecosystem thresholds of 30%; and (iii) landscape design and planning principles that protect large remnants, preferably > 2000 ha, as core habitats. Under these retention thresholds, no further clearing would be permitted in the extensively cleared biogeographic regions such as Brigalow Belt and New England Tablelands. Some elements of the biota, however, will require more detailed knowledge and targeted retention and management to ensure their security. The application of resource sustainability and economic criteria outlined elsewhere in this volume should be applied to ensure that the biogeographic regions in the north and west of Queensland that are largely intact continue to provide extensive wildlife habitat.
On the importance of habitat continuity for delimiting biogeographic regions and shaping richness gradients
