The extent and reasons behind the application of fire by the original Australians, while popular in the media and several books, in the scientific community it is a large unknown. In some parts of Australia, particularly central and northern Aus we have good knowledge due to this information being passed through the generations. In other areas, such as the south-east, with respect to the traditional owners of these lands, this is largely lost due to the fragmentation of the groups and other post settlement influences on the population. Some information is still available, but again, this is largely incomplete and the context of the use may have been lost.
This question has been looked at by the scientific community as the extent of indigenous burning is perhaps the most contentious issue in Australian ecology. When scientists have sampled the tree-ring, lake charcoal and pollen records it has been found to be extremely difficult to measure the traditional use of fire as what has been found is the levels of fire in SE Aust was extremely low. There was certainly periods of frequent fires across different areas but it is difficult to put this fire in any context of those periods. Variations in climate may have been more of a factor. In the Aust alps it has been clearly shown in tree ring records (fire scars) for example that the arrival of Europeans changed the fire regime - more fire. Look up Lindsay Pryors work from the Brindabellas.
Ultimately, we are now in a different climate regime and it is perhaps time to change our approach to fires and do away with hazard reduction practices and focus on asset protection. Former NSW fire commissioner Greg Mullins gave a very interesting interview to the ABC today Breakfast - Breakfast - ABC Radio - it starts at 2:20 and is well worth the listen.

