Distribution and persistence of temporary wetland habitats in arid Australia in relation to climate

The distribution and area of temporary wetlands across the arid zone of Aus tralia are highly variable. Any change in their distribution or extent due to climate change and/or extraction of water has the potential to adversely impact dependent biota. Satellite imagery was used to determine the spatia l and temporal distribution of wetlands across arid Australia over an 11-ye ar period. Synoptic climate data were examined to identify the weather syst ems that caused wetland filling events. Simple threshold models relating ra infall to wetland filling for seven large regions of Australia were develop ed to examine patterns of wetland filling over the last 100 years. These da ta were used to examine the climatic processes that drive wetland filling a nd the likely impacts of climate change on wetland distribution. The strong est climatic influence on wetland filling in the arid zone was tropical wea ther systems. Their influence extended into southern regions and their effe cts were often widespread. Variation in wetland area in all regions of the arid zone was high. The Lake Eyre Basin experienced more large flood events than other regions and had the most large, persistent wetlands that remain unregulated by humans. Hindcasting of past filling events indicated that t here was a general pattern of frequent wetland filling across inland Austra lia in the 1910s, 1950s and 1970s, and less frequent wetland filling in the late 1920s, 1930s and 1960s. Furthermore, there appeared to be no period g reater than 12 months over the previous 95 years when there was no predicte d wetland filling in the arid zone. Wetland ecosystems dependent on a few i nfrequent heavy rainfalls are clearly vulnerable to any change in frequency or magnitude of these events. Climate change that results in a drying or r educed frequency of large flood events, exacerbated by extraction of water for agriculture, could be catastrophic for some biota, particularly waterbi rds, which use a mosaic of wetland habitat at broad spatial scales.