Bush regeneration after fires

This episode was first broadcast in 2006


In late January 2006 bushfires ravaged Victoria's Brisbane Ranges National Park, 80 kilometres south-west of Melbourne. It is not even 12 months since the bushfires and remarkably there are signs of regeneration - the trees are shooting, and the native wildflowers and orchids are springing to life in the burnt-out bushland.

Peter Box is a ranger with Parks Victoria and has witnessed the cycle of growth, destruction and regeneration of the Brisbane Ranges park for nearly two decades.

He says the fire ferocity was severe. "The fire burnt out roughly 7,000 hectares in a day - trees were burnt off at the ground, so it just took out everything. I've been in the area for 18-odd years, and hadn't seen anything like it before.

"The bush recovered quickly and in the picnic grounds we're noticing young eucalyptus trees starting to shoot in damp areas after a little rain.

"Some of the gum trees have epicormic growth, that's what you see up the sides of them. That is how they keep surviving after the fire.

"The ground covers came back relatively quickly. Once we had rain, the sedges, and bracken ferns started to shoot and over spring the wildflowers and orchids have come up."

One of the most remarkable things about regeneration after fire is the emerging forest of grass trees, known as Xanthorrhoeas. I love them because of their grassy skirts and wonderful architectural spikes of hundreds of thousands of individual flowers. It's a rare sight but a unique symbol of the Australian bush - a true gallery of grass trees.

After the fires only black stumps were left. The growth has happened since. Grass trees or Xanthorrhoea australis only flower after a fire.

According to Peter, the Aborigines used the flower spikes and dipped them in water to make a sweet drink or even melted down the resin to use as a type of glue to put heads on their spears.

Unfortunately there is a huge problem of grass trees dying back. It is caused by a root rot, a fungus called phytophthora, and it is the cinnamon fungus that causes the leaves to yellow and then the plant sinks away and collapses. The surrounding gum trees can get it too - it is fairly common in the Brisbane Ranges and other parts of Australia. It is spread by infected soil and infected plants.

To overcome this, an implement called a cinnamon fungus hygiene station or more affectionately "an Anakie scrubber" is used. It cleans and removes all organic material from your boot and then a spring-loaded pressure plate immerses the soles of the boot into a chemical. A little bit on a boot will completely kill the fungus. Peter says that bush walkers are encouraged to stay on the tracks where possible.

"The wildflowers such as lomandras and milkmaids have come back well and there are an amazing number of native bees hovering around the flowers.

"It's a good sign and means that the flowers will be cross-pollinated and continue next year," he says.

Some of Peter's favourites include a chocolate lily with its beautiful little flower. There has also been a good show of orchids this year including red beak orchids Lyperanthus nigricans that only flower after a fire. They normally put up a leaf but will not flower unless fire affected.

The immediate impact of a bush fire can be devastating on both the environment and people who are affected by the damage, but long term it can help replenish and revitalise the Australian bush.

Peter believes the Australian bush has evolved to use or accommodate fire as a means of renewal. The burnt canopy means there is sunlight coming in and more heat on the ground, so it's all good for the plants.




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