Boom means bust: interactions between the El Ni?o/Southern Oscillation (ENSO), rainfall and the processes threatening mammal species in arid Australia

摘要

We collated an environmental history for a 8580 km2 study area in the Simpson Desert, Australia. Quantitative and qualitative data on climate, land-use, fire history and ecosystem dynamics were used to construct a chronology of processes threatening terrestrial mammal species. Over the last 150 years there has been the transition in land tenure from a hunter–gatherer economy to pastoralism, the loss of 11 mammal species, the cessation of small scale burning by Aboriginal people and the introduction of the fox and cat. Annual rainfall was highly variable and was influenced by the phase of the El Niño Southern Oscillation (ENSO). Irruptions of rodents, marked increases in the populations of native and introduced predators and extensive wildfires were associated with the La Niña phase of ENSO and occurred when rain-year (July–June) rainfall approached or exceeded the 90th percentile of the historical rainfall distribution. Large rainfall events in arid Australia have been viewed traditionally as the ‘boom’ times that benefit wildlife and pastoral production. However, because of hyper-predation and the risk of wildfire, we show that the years including and immediately following flooding rains should be identified as critical, or ‘bust’ periods for wildlife and conservation management. ENSO related climatic forecasts appear to be useful cues which can be incorporated into fire and predator management strategies in arid Australia. Studies such as this, which utilise a broad range of data types across extensive areas, can identify the timing and potential of threatening process not possible using contemporary studies alone.