Australia: The Land Where Time Began

A biography of the Australian continent 

Tansley Review No. 101 – Impact on Australian Biota of Aboriginal Landscape Burning

The environmental impact of Aboriginal landscape burning is one of the most complex and contentious issues in the ecology of Australia. This issue is central to the development of appropriate strategies for the conservation of the Australian biodiversity, as well as for the development of a comprehensive understanding of the dynamics and evolution of the Australian biota. There is little doubt, based on ethnographic evidence, that burning by Aboriginal groups played a central role in maintaining the landscapes that were subsequently colonised by Europeans. The indispensability of fire as a tool in traditional Aboriginal economies has been documented by both European colonists in the 19^th century and anthropologists in the 20^th century; hence the description of their burning practices as ‘fire-stick’ farming. According to Bowman fire was used by the Aboriginal People for short-term outcomes, such as providing suitable habitats for herbivores or to increase the local abundance of food plants, though it is not clear if the Aboriginal People had a predictive ecological knowledge of the long-term consequences. It is suggested by a large body of ecological evidence that the result of Aboriginal burning was substantial changes in the geographic range of many vegetation types as well as their demographic structure. One suggestion that is widely accepted is that the burning by the Aboriginal People was an important factor in the formation of habitat mosaics that favoured the abundance of some mammal species, and the maintenance of habitats that were essential for the survival of specialised fauna, which were infrequently burnt. Bowman suggests that in the monsoon tropics Aboriginal fire was critical in the maintenance of at least 1 tree species (Callitris intratropica).

The original impact of humans on the Australian environment is necessarily speculative, as a result of the vague, disputed time frames that have been proposed for the waves of colonisation and patterns of shifting settlement of the Aboriginal migrations in the late Quaternary. The cause and effect of climate change, vegetation change, and burning that occurred through the late Quaternary involves an inherently circular argument. The initial impact the Aboriginal people had on the landscapes of Pleistocene Australia cannot be determined unequivocally by the evidence provided by charcoal and pollen from long sedimentary cores. The hypothesis that Aboriginal fire was primarily responsible for the megafauna extinction in the Pleistocene; was critical for the habitats of small mammals that have become extinct since the European colonisation; initiated widespread acceleration rates of soil erosion in either the Pleistocene of the Holocene; or forced the evolutionary diversification of the Australian biota, is not supported by the sparse available evidence. It is possible that burning caused the extinction of some plants that were fire-sensitive, as well as the animals dependent on habitats that were burnt infrequently; burning must have also maintained vegetation types such as grasslands, that were structurally open, and also extended the range of species that were fire-adapted, e.g. Eucalypts, into areas that were climatically suitable for rainforest. It is proposed here that palaeoecological research of prior impacts of Aboriginal People must give way to focused studies of the role different anthropogenic fire regimes in contemporary ecosystems that have not been destroyed by European colonisation. Bowman suggests it is crucial for understanding the role Aboriginal burning had on the unique, rich biodiversity of Australia.

Sources & Further reading

1. Bowman, D. M. J. S. (1998). "Tansley Review No. 101. The Impact of Aboriginal Landscape Burning on the Australian biota." New Phytologist 140(3): 385-410.