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Fire, Erosion and the End of the Megafauna

The distribution of dated erosion events in Tasmania

The distribution of dated erosion events in Tasmania over the past 105,000 years in relation to human arrival and the extinction of the megafauna. Note the increase in the number of erosion events after 40,000 years ago and the absence of a peak in erosion events in the cold period around 65,000 years ago. The image of the giant marsupial Zygomaturus trilobus is by Nobu Tamura.

By Peter McIntosh

Tasmania’s erosion history links ancient Aboriginal burning practices with the demise of Tasmania’s megafauna.

Peter McIntosh is Senior Scientist (Earth Sciences) with the Forest Practices Authority in Tasmania.

The full text of this article can be purchased from Informit.

People have occupied the Australian mainland for at least 56,000 years, but Tasmania was the last part of Australia to be colonised – the oldest dated habitation layers in the state accumulated about 40,000 years ago.

The ecological effect of human colonisation of Australia has been debated at length, with particularly strong views exchanged on the role of humans in the extinction of the megafauna. Were these beasts hunted to extinction? Or couldn’t they cope with a changing climate? Or did humans change the ecology of the landscape so drastically that they starved? Or was a combination of these processes responsible?

The early European visitors to Tasmania remarked on the widespread burning of vegetation by the Aboriginal population. It is highly likely that deliberate fires have been lit for thousands of years and that the frequency of landscape fires increased after human arrival. Fire was the only effective tool the early immigrants had for clearing tracks, flushing out game and producing fresh new growth to entice animals into open areas.

Botanists, soil scientists and archaeologists have all argued that the vegetation and soil pattern in Tasmania is partly a result of fire. The abrupt transition between “wet” eucalypt forests (with a dense fire-

sensitive understorey and nutrient-rich bioturbated soils) and “dry” eucalypt forests (with a...

The full text of this article can be purchased from Informit.