Alternative burn theory

By Chris Thomson | posted on January 17, 2019

A SCIENTIST who turned prescribed burns on their head over east by finding fires there make forests more likely to burn is in the Great Southern to see if he can help reduce bushfire risk here.

This week, University of Wollongong fire behaviour specialist Phil Zylstra has inspected tingle forest at Douglas Hill, beside Frankland River, and met with conservationists and senior Department of Biodiversity, Conservation and Attractions staff.

“My research contradicts one of the central assumptions in Australian fire management – that forest simply accumulates fuel over time and becomes increasingly flammable,” Dr Zylstra said.

He looked at the Australian Alps bioregion, from the highest mountains down to sea level.

“For close to 100 years, graziers and naturalists have been saying you shouldn’t burn snow gum country there because it makes it thicken up and become more flammable,” he said.

Dr Zylstra focused on the bioregion’s fire history, not on theory.

“I found it wasn’t just snow gum forest, it was all forest, so everything from low dry woodland to tall wet forests and right up to the treeline, all areas were far more flammable when they were in a regrowth phase,” he told The Weekender.

“There has been a consistent pattern there where straight after fire it’s not very flammable for a little while because you’ve cleared a lot of the vegetation, but you also germinate a lot of shrubs and you cause that regrowth to happen.”

He said that as the forest was re-building, it was a lot more flammable.

“It’s not until it gets to that stage when you’ve got a well-developed tree canopy and that initial flush of shrubs starts to thin out again that it becomes less flammable then as a mature forest,” he explained.

Denmark landholder Tony Pedro, instrumental in Dr Zylstra’s visit, has been a member of the East Denmark Bushfire Brigade since 1970 but does not participate in the brigade’s prescribed burns.

“My interpretation of it all came from my first-hand experience as a child living there in the 1960s and being able to easily walk and sometimes run through that forest down to the river to catch marron,” he said.

“And once prescribed burning started, I found that it was this impenetrable thicket.

“I then moved to Denmark in the 1970s to where I’m farming now and found exactly the same phenomenon in the jarrah forest.”

At Mr Pedro’s Denmark property there are about 400 hectares of uncleared land, most of which has not been burned for 60 years.

“The long unburned country opens out into a parkland,” he said.

“I think what’s happening there is that evolution over hundreds of thousands of years has worked out a system to learn to manage itself.

“It doesn’t need to be constantly fired.”

Dr Zylstra said he was “intrigued” by what Mr Pedro had told him.

“It seems like a very, very similar scenario to what’s happening in the Alps, but I don’t just want to go off hearsay, so we will go through this very thoroughly,” he said.

“I’m hoping with these surveys [at Douglas Hill] to fill some gaps in the knowledge that we’ve got, and run it through some intensive analysis to see whether that is what’s actually going to happen.”

He considered recently expressed opinions that Aboriginal people burned forests more than the farmers who followed to be misconceived.

“Indigenous people did burn very often but their fires were very controlled, so even in areas say in the Western Desert, The Pilbara, where there is still fully intact burning traditions, they’re burning less than one per cent of the landscape,” he said.

“You’ve now got people lighting up tens of thousands of hectares at times from helicopters, people buying vehicle-mounted flame-throwers to be able to light up as fast as they can from roadsides.”

Among Traditional Custodians in the Great Southern and Southwest who Dr Zylstra has consulted is Menang man Harley Coyne.

Mr Coyne said he wanted to see the forest preserved but was “not dead against” prescribed burning.

“The issue around tingle forest is that, if it’s going to be managed with fire, they need to be managed intimately,” he said.

“And that, itself, is the difficulty because there can’t be any guarantee that if a prescribed burn went through there that those trees wouldn’t be affected.

“As a Traditional Owner, I welcome any research that will add information and help protect those areas.”