The fire, human and climate nexus in the Sydney Basin, eastern Australia

It is widely believed that Australian Aborigines utilized fire to manage many landscapes; however, to what extent this use of fire impacted on Australia's ecosystems remains uncertain. The late Pleistocene/Holocene fire history from three sites within the Sydney Basin (Gooches Swamp, Lake Baraba and Kings Waterhole) were compared with archaeological and palaeoclimatic data. The Gooches Swamp record appeared to be most influenced by climate and there was an abrupt increase in fire activity from the mid Holocene perhaps associated with the onset of modern El Nino-dominated conditions. The Kings Waterhole site also displayed an abrupt increase at this time, however there was a marked decrease in charcoal from 3 ka. Similarly Lake Baraba displayed low levels of charcoal in the late Holocene. At both Kings Waterhole and Lake Baraba archaeological evidence suggests intensified human activity in the late Holocene during this period of lower and less variable charcoal. It is hence possible that Aboriginal people strongly influenced fire activity in some areas of the Sydney Basin during the late Holocene perhaps in response to the increased risk of large intense fires as an ENSO-dominated climate became more prevalent. The fire history within the Sydney Basin varies both temporally and spatially and therefore it is inappropriate to apply a single fire regime to the entire region for landscape management. This work also has implications for future fire incidence associated with climatic variability under an enhanced Greenhouse effect.