Fire makes forests likely to burn: study

Dominica Sanda

Controlled burns are a common measure used by firefighters in Australia to prepare for bushfires but new research has found fires make some forests more likely to burn.

The study by University of Wollongong researcher Philip Zylstra focused on the Australian Alps which stretch across Victoria, NSW and the ACT and found on average fires increased the risk of the forests burning again.

The study looked at 58 years of fires in 12 national parks measuring 36 million locations over 1.5 million hectares.

Dr Zylstra found fires in the Australian Alps National Parks had been smaller and less severe in long-unburnt forests.

"It contradicts the idea that fire will usually reduce the risk," Dr Zylstra told AAP on Tuesday.

"The message from many ecosystems across the world is that while we've been assuming otherwise, fire has been breaking their defences and feeding more fire."

With a longer and more severe fire season in Australia, Dr Zylstra says some forests are being wiped out permanently because of frequent fire.

While the study doesn't suggest hazard reduction burns should stop, it does recommend protecting older forests as they are the least flammable.

Tall, wet ash forests are highly flammable until they reach maturity at 20 years while unburnt, mature ash forests are more than eight times less likely to burn than younger ash forests, Dr Zylstra said.

"Old forests need to be protected," he said.

"We should nurse older regrowth into its mature stages. This will help the forests survive and make them more resistant to climate change."