Much of Australia’s biodiversity is renowned for its ability to deal with massive ecosystem shocks (e.g. fire, extended periods of dry or wet, extreme weather events such as cyclones). During the past few decades, we have learned more about the multitude of strategies used by different species that provide resilience to change. However, although our biodiversity is well adapted to past change, including a certain frequency of extreme climate events, it is not necessarily well adapted to future rates of environmental change, particularly given the often very fragmented and degraded habitat in which change now occurs.
The evolution of adaptive mechanisms in our flora and fauna provides strong evidence of past resilience. However, concern has been growing that some ecosystems are already unable to respond to ongoing global change. In south-western Australia, the past 40 years have seen a climate shift, with reduced precipitation and increasing temperatures; the period from January 2000 to the present was the driest on record (BoM & CSIRO 2014). Above and beyond this decadal trend, there have also been recent droughts, with the summer of 2010–11 being one of the driest and hottest years on record for much of the region (2013, 2014 and 2015 were even hotter). The consequence of extended periods of hot temperatures and reduced rainfall on the resilience of ecosystems is not well understood. For instance, in the wettest parts of south-western Australia, streamflow has declined by more than 50 per cent since the mid-1970s, yet we do not have the long-term data to determine biodiversity decline as a result of this phenomenon.
Other ecosystems considered to have reduced resilience include montane communities such as the Eastern Stirling Range Montane Heath and Thicket, which has been assessed as critically endangered based on its naturally limited geographic extent, in combination with the impacts of the plant pathogen Phytophthora cinnamomi (Barrett & Yates 2015). A strong signal for decreased resilience in south-western Australia has been recorded in species generally considered to be robust to climate impacts, such as the region’s 2 dominant tree species (Eucalyptus marginata and Corymbia calophylla). More than 4 years of measurement following the 2010–11 drought showed a failure to recover structure, suggesting that repeated drought has prevented stand development from occurring, and only partial regrowth (Matusick et al. 2016).