Drought down-under: Dieback controls of tree dynamics in Australian savanna

Australia is known as a land of droughts and flooding rain, but climate forecasts predict an even greater incidence and severity of drought in Australia. Up until recently tree dieback was thought to signify a diseased and unhealthy landscape. Recent research raises the possibility that drought-induced tree death may in fact be a natural phenomenon that resets woodland structure after decades of vegetation thickening during favourable conditions. This scenario is supported by landscape histories derived from the records of the nineteenth century explorer Ludwig Leichhardt. The patchiness of dieback following droughts confounds simple explanation, but there is some evidence that it relates to local variations in soil-water holding capacity and perhaps infiltration. Eastern Australia has been recently gripped by drought and there are many anecdotal reports of widespread tree death from northern New South Wales to central Queensland. Planned future research includes further survey of drought-induced dieback coupled with remote-sensed detection; analysis of the global rainfall patterns of drought using a simple multi-year deficit index; and more detailed understanding of the recovery processes that follow drought.