PhD student examines lost eucalyptus canopy at Wilsons Prom

THE IMPACT of specific climate driven changes on eucalypt forests at Wilsons Promontory are being studied by PhD student Aaron Heap.

Aaron is examining patches of forest that have lost eucalyptus canopy due to being repeatedly razed by fires within shorter intervals than species can tolerate.

This can lead to some species of eucalypts being unable to regenerate which then causes areas to transform into an alternative forest type.

Wilsons Promontory, unlike most other Victoria bushland has had relatively minimal human disturbance since colonisation, which helps to reduce the variables of human interference when comparing and studying the areas.

“Wilsons Promontory provides an example of how repeated short interval fires can prevent the regeneration of a Eucalyptus canopy in a range of ecological vegetation classes. The ‘destocking’ of forests can dramatically alter the composition, structure, and function compared to forests with a eucalypt overstorey,” Aaron said. 

There are about 20 different types of eucalypts on the Prom and Parks Victoria are discovering many hybrid and unique species as they are collecting seeds and reseeding some of the fire affected areas in an effort of ecological restoration.

Aaron is working alongside this team to inform his study but is focused on five particular species of eucalypts in areas without canopy and which have existed like that since about the 1950s.

“The time frame between eucalypts regenerating depends on the species, however it could be 15 to 20 years. There’s also species of eucalyptus that after a fire, their response is to just resprout, so they’re not so reliant on reseeding to survive, but it’s going to show that if fires happen at intervals too frequent, that will affect their ability to resprout, and so they’re in the same kind of predicament.”

Aaron has begun collecting data for his three-year investigation and is interested to find out what actually happens to the areas and what ecological changes do occur.

It is theorised that frequent fires and the loss of canopy could lead to these eucalypt species eventually becoming locally extinct, but Aaron remains open to all outcomes.

“It’s commonly assumed that it’s a negative impact and that makes sense that it is, but nobody’s actually going out there and measured it.

These areas are considered to have lower biodiversity values, lower carbon sequestration, less habitat availability, and they’ve also been described as being contributing more to landscape flammability.”

“I’m measuring things like how much ground carbon there is, what are the biodiversity assets? How do you seed these areas, how structurally diverse the areas are.”

“I’m also looking at measuring the fuels that are in these two forest types and comparing the fuel between these two. I should be able to look at how these areas influence landscape flammability.”

Aarons last piece of research will be to look at the cost benefit analysis of restoring these areas, and if it is simply part of an evolving landscape that is potentially self-sustaining.