Thanks Mav - here's a bit more on your comments.....

In particular I refer to your emphasis of the word "natural" and suggest it may be incorrect. Fire is an important part of the growth cycle of much of our forests and heath lands but the plants' reliance upon naturally occurring fires is questionable.

Depending upon which school of archaeology you follow, aboriginals came to this land somewhere between 40,000 and 60,000 years ago. According to the fossil record, their arrival had a dramatic (even catastrophic wouldn't be too strong a word) impact on the number and type of animal and plant species. Of course the arrival of European settlers 200 years ago took the destruction to far greater levels, but nonetheless a lot had changed in the pre- and post-human landscape.

The prime reason for the change due to aboriginal inhabitation was fire. Being nomadic hunter gatherers, fire was the aboriginal people's main tool in smoking out animals and for ensuring others were attracted (by the fresh shoots) in the revegetation phase. There were sundry other benefits such as simply clearing the land for easy pedestrian transit. (I don't know if you've ever walked naked through spinifex grass country - but it would be an extremely painful experience - it is even when fully clothed and wearing protective gaiters!!)

Anyway, the point is that the plant species present today are dominated by those that could survive fire or, as mentioned, those that that rely upon fire or smoke for seed germination.

BTW, I believe it would be incorrect to suggest that the plants have evolved to rely upon these methods since humans came. 40,000 to 60,000 years is probably not long enough. Hence my comment that the plants we see are those that were already adapted to cope with periodic fires.

stales