Inferring drought and heat sensitivity across a Mediterranean forest region in southwest Western Australia: a comparison of approaches

Changes in climate trends and extreme climatic events are increasingly impacting on forests around the world. In order to better understand how and where major ecological and climatic changes will affect our forested ecosystems, tools based on landscape sensitivity analysis need to be developed to help inform sustainable forest management. This study was undertaken in the Northern Jarrah Forest (NJF) region in the Mediterranean climate of southwest Western Australia. Extreme drought and multiple heatwaves in 2010/2011 resulted in large-scale tree canopy dieback in the NJF. In this study, we used Landsat satellite imagery to (1) accurately map the damaged areas, (2) produce a damage probability model and (3) compare the model with a probability model derived from data collected through an airborne flight survey. We found that the Landsat-derived Normalized Difference Vegetation Index was a good indicator of drought/heat induced damage in the NJF region. Both probability models identified the same set of topography and climate-related factors for determining the probability of drought/heat damage within the landscape. Extrapolation of the Landsat satellite method-based model, however, produced a more deterministic and useful drought/heat damage sensitivity map for the NJF region. The techniques and tools developed, and applied, in this study can readily be transferred to other regions around the world and can assist in the sustainable management and timely climate adaptation efforts to accommodate our future forests.