Dealing with threats: Integrating science and management

Threats to biodiversity are pervasive and diverse. The management of these threats is the major focus of conservation biology. We briefly reviewed the taxonomy of direct threats to biodiversity as a means of examining legislated planning actions and strategies for managing threatening processes in eastern Australia and propose a simple classification of five general types of threat. These include the major threats of destruction and fragmentation of habitat and global climate change; threats that relate directly to changes in disturbance regimes (e.g. fire and water); threats related to reduced functionality of biological interactions or life-cycle processes (e.g. due to invasions of exotic species); and over-exploitation affecting specific groups of plant and animal species. We applied this five-level classification to the listings of key threatening processes under legislation in three Australian jurisdictions (Commonwealth, New South Wales, Victoria). A small core group of threats are currently common to all three jurisdictions, including clearing of native vegetation, climate change and particular alien predators and diseases. The bulk of listings reflect differences in emphasis between jurisdictions, with the Commonwealth having not listed threats related to weeds or disturbance regimes. To manage all types of threats, we need a clear understanding of cause and effect combined with adaptive management strategies for amelioration. We use selected case studies to show how a process-based understanding of threats can be incorporated into conservation management. In fire-prone ecosystems in New South Wales, for example, threats posed by increased fire frequency have been addressed in fire planning by prescribing management thresholds, derived from knowledge of the limits set by seed bank dynamics in relation to species persistence. Monitoring of species after fire allows re-evaluation of recommended intervals. In arid and semi-arid systems, grazing by introduced herbivores has disrupted the recruitment of new individuals into plant populations, resulting in long-term decline of a number of perennial plant species across extensive proportions of their ranges. In conjunction with long-term monitoring of recruitment patterns at selected locations, control of introduced herbivores is being used to address this threat. Finally, strategies for dealing with threats of a changing climate (including managing the capacity of species to disperse across the landscape) must include strategies for minimizing habitat loss and on-site management of existing threats.