Potential future scenarios for Australia's native biodiversity given on-going increases in human population
Introduction
Native biodiversity is the collection of native species, genetic and ecological variation in a given area. Native biodiversity is integral to ecosystem function (Soliveres et al., 2016), and provides many ecosystem services upon which humans rely (Mooney et al., 2009). However, native biodiversity is in steep decline at global (Millenium Ecosystem Assessment, 2005), national (Evans et al., 2011) and local (Fischer et al., 2010) spatial scales. There are many causes, but land-use change (Newbold et al., 2015) and climate change (Intergovernmental Panel on Climate Change, 2015) are at the forefront of pressures that are affecting native biodiversity adversely (Selwood et al., 2015). We need to find ways to achieve a ‘safe operating space’ for the long-term persistence of humans, the biota and environmental ‘health’ (Rockström et al., 2009b).
While the current status and pressures on native biodiversity are reasonably well known (Newbold et al., 2015), what is much less certain is the future path we might choose for better balancing human wealth and welfare with the maintenance of the environment, including native biodiversity (Steffen et al., 2011a). There is a need for a forward-looking framework to envisage how native biodiversity, the global environment and human needs will play out in different ‘futures’ (Steffen et al., 2011b). Futures studies use various methods to think about the future to inform current strategic thinking, decision-making and action (Rigby and Bilodeau, 2007). A commonly used method is scenario development (Amer et al., 2013), and we see the construction of plausible scenarios as an important tool for anticipating and dealing with native biodiversity declines before they become irreversible.
Scenarios are used increasingly, in many different fields and for different purposes (Börjeson et al., 2006) to deal with uncertainty (Schoemaker, 1991) and to help to make better decisions (Wilkinson and Kupers, 2013). Amer et al. (2013) provided a comprehensive review of the scenario-planning literature, covering scenario-development approaches, quantitative techniques, and means for identifying the most critical drivers of change. Much of future-studies work uses multiple scenarios (Wilkinson, 2009), connecting different futures with the present (Martelli, 2001) through feasible chains of causal relationships (Kahn and Wiener, 1967). Scenario development facilitates discussion on assumptions about the future and precipitates thinking (Raskin, 2005), and expands perspectives that identify influences that might otherwise be overlooked (Wilkinson and Kupers, 2013).
We build on previous scenario developments (Cork et al., 2012, Raupach et al., 2012, Costanza et al., 2015) and focus specifically on the pressures affecting native biodiversity for Australia as an exemplar. Human responses to some drivers of change, especially climate change, are key elements of our approach (Fig. 1) because these are likely to be faster than the biotic responses to climate change. The set of scenarios spans a wide range of possible future paths for Australia. In the following, we describe and discuss the implications of each scenario on future native biodiversity.
Section snippets
Methodology
Our development of multiple scenarios is underlain by two core assumptions (about Australia's population and the greenhouse-gas emissions scenario) and by a suite of ‘drivers of change’. While the assumptions limit the potential range of futures, the ones we use are both crucial and most likely at the current time. The drivers were selected through a rigorous process described elsewhere (Pepper et al., 2016), so we do not describe them in detail here.
Scenarios
Narrative descriptions of scenarios are provided below. The narratives expand upon scenario fundamental attributes, which are functions of combinations of settings on the drivers presented in Table 1.
Discussion
The degrees to which the nine scenarios affect native biodiversity differ substantially, mediated by the mechanisms listed in Table 3. The mass movement of human population into northern Australia must have significant detrimental effects on Australia's native biodiversity because the northern region is much less affected than the south at present and is one of the most continuous woodland ecosystems in the world (Mott et al., 1985). While feral plants and animals and extensive grazing have had
Acknowledgements
The work was supported by an Australian Research Council Discovery Grant (DP120100797) and by funds from the Institute for Applied Ecology, The University of Canberra. We thank N. G. Yoccoz and an anonymous reviewer who made useful comments on an earlier version, which clarified many points. We appreciate input from M. McGeoch and P. Unmack during early stages of the work.
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