Fire and the long-term effects
Prescribed burning, long a part of Australian life, keeps people and property safe in fire season by reducing the fuel in vegetation around towns. It also allows fire-dependant plants to germinate.
However, according to Professor Clarke, the process can have a devastating impact on some wildlife. Too-frequent burning could jeopardise the survival of threatened species, while the effects of even a single fire can last for well over a century.
In 2006, land managers planned more prescribed burning in the Mallee region of Victoria and southern Australia. Professor Clarke and his team saw that as an opportunity: to study the long-term effects of fire on plants, mammals, birds, reptiles and invertebrates like termites and scorpions.
Thinking of the animals
In Australia, there’s a common belief that our native animals have adapted to living with fire.
Professor Clarke wasn’t convinced.
‘If we’re adding fire to the landscape to protect life and achieve ecological outcomes, above and beyond what nature adds, then we really need to know what we’re doing,’ he says.
As a zoologist, he was concerned about animals. Does fire management, as currently practised, consider their needs?
‘While many plants might be able to bounce back or re-sprout from some hard seed or a tough root system,’ he points out, ‘animals don’t have that luxury. They either die in the fire or its aftermath, or they flee, but many are incapable of fleeing. So re-colonisation of a burnt landscape typically relies on immigrants from some unburnt bit of the land.’
Professor Clarke says we’ve lost knowledge of how often Aboriginal people burnt particular landscapes and we can’t generalise from one habitat to another, because you can get it profoundly wrong.
‘In many cases we’ve lost knowledge of how often Aboriginal people burnt particular landscapes,’ he says. ‘They might have burnt grasslands really often, but wet mountain forests hardly ever or not at all. The devil is in the detail, and we can’t generalise from one habitat to another, because you can get it profoundly wrong.’
Harnessing technology to help wildlife
A joint study by a team from La Trobe and Deakin University showed that most of the rare and threatened birds in the Mallee region, such as the endangered emu-wren, need a long fire-free period to thrive.
But the difficulty lay in determining how long the region had been fire-free. And that challenge led to a world-first technique.
The team measured the diameters of 40,000 trees and then developed computer programs to enable a satellite to recognise those trees from space. They were then able to go ‘back in time’ for a period of 100 years, mapping old-fire regions and also identifying precious unburnt areas of the Mallee.
They then produced maps that displayed parts of the habitat that hosted threatened birds, giving rangers valuable knowledge about which areas were most important to protect.
Changing how fire is managed
Until recently, the government used annual hectare targets for the prescribed burning of public land.
As Professor Clarke explains, ‘This led to a perverse outcome, which didn’t always result in burning where it would make people safer or achieve ecological benefits, but rather, to simply to meet a target.’
However, the Department of Environment, Land, Water and Planning, and Parks Victoria, have been great supporters of the team’s research.
They're keen to embrace the study’s recommendations, changing how they manage fire and embracing a ‘risk-based strategy’. This means burning where you can make the biggest risk reduction for people and wildlife.
La Trobe's research has nurtured a new generation of fire ecologists, and is now branching out to different parts of Victoria. But there’s still much to learn.
According to Professor Clarke, climate-change modelling suggests natural fires will not only become more common worldwide, they’ll be more frequent and more intense.
To learn to live with fire, we need to understand how long the impacts of fire last, and what effect it has on wildlife and people.
‘Everybody is trying to live with more fire,’ he says. ‘To do that sensibly, we need to understand how long the impacts of fire last, and what effect it has on wildlife and people.’
With this valuable research under way at La Trobe, our communities and environment will be more resilient and far better equipped to face the problems of climate change.
Professor Michael Clarke is the Head of the School of Life Sciences, Professor of Zoology at La Trobe University.
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