Wednesday, June 6, 2012

Western Australia’s catastrophic forest collapse

Recent, unprecedented, climate-driven forest collapses in Western Australia show us that ecosystem change can be sudden, dramatic and catastrophic. These collapses are a clear signal that we must develop new strategies to mitigate or prevent the future effects of climate change in Australian woodlands and forests. But society’s view of forests is ever-changing: are we willing to understand ecosystems and adapt to changing conditions?

The south west of Western Australia has experienced a long-term climate shift since the early 1970s, resulting in dryer and hotter than average conditions. This shifted baseline, or average, has also led to more frequent extreme events. In 2010, the region experienced the driest and second hottest year on record.

These climate changes have resulted in significant decreases in stream-flow and groundwater levels. For example, formerly permanent streams now stop flowing for considerable periods. Groundwater levels have fallen up to 11 meters in some forested areas, with larger decreases in populated areas. Clearly, soil water reserves have dried out substantially and will likely continue to do so; we are now starting to see the implications of this. Although most of the West Australian society, particularly those in urban environments, may be well-buffered from these changes, ecosystems are not.

The climatic changes occurring in the south west of Western Australia are contributing to deteriorating woodland and forest health. In the past 20 years, insect infestations and fungal diseases have plagued many iconic tree species, including tuart, wandoo, flooded gum, marri, and WA peppermint, increasing their mortality rates. Many of these disorders are likely triggered or incited by changing climate conditions. More