The past few months have seen vast parts of the mountains around Canberra and reserves within the city bathed in smoke from large-scale prescribed burns (or hazard reduction burns). A similar scene has characterised other cities and regional cities around southern Australia including Sydney and Melbourne.
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These prescribed fires are lit to reduce the risk of high-severity wildfires and protect people and property. But do they? And, is this a cost-effective and health-effective way to protect people and the bush?
Our recent research has shown that some woody ecosystems, including native forests and woodlands, can become more flammable (not less) as a result of prescribed fires. This is because disturbances such as prescribed burning (as well as logging and forest thinning operations) lead to pulses of flammable regrowth. This locks in the need to keep doing prescribed burning and in the words of a former fire chief, creates a never ending "have to burn" cycle. In fact, the fire chief was totally unsurprised by our scientific results showing that prescribed burnt forests were more flammable - he said that it was finding what many firefighters had known for years! Indeed, there are some now within agencies in the ACT government that are recognising that the idea of widespread prescribed burning might be counterproductive. They have come to discuss this issue with us. Key to these discussions has been the empirical evidence showing the reality that prescribed burning too often has short-term benefits, but long-term costs.
Sadly the light dawning on some people in our land management agencies about the problems of prescribed burning has not shone in many others where it should. A case in point is in Western Australia - the mecca of prescribed burning globally where massive areas are burnt in hazard reduction burns every year, but unfortunately also where there are have been many very damaging wildfires in recent times that have destroyed property. New research shows that continued prescribed burning is maintaining forests in south-west Western Australia in its most flammable state, where forests are now dense with regrowth from the last burn. Government agencies in Western Australia seem deaf to these findings and are hell bent on maintaining the status quo of ongoing major burning programs. The impacts of doing this seem pretty obvious.
Perhaps as concerning as the effects of prescribed burning on elevated flammability in woodlands and forests is its effects on human health from the massive amounts of smoke that it generates. In fact, people are far more likely to die from smoke-related respiratory problems than in a wildfire. There is an extensive body of health research demonstrating this.
Widespread prescribed costs a lot of money, time and other resources. The return on this investment seems limited at best and highly counterproductive at worst. In contrast, evidence increasingly tells us we need to invest in faster detection and suppression. State and territory governments in many parts of Australia need to rethink the notion that they can burn their way out of the wildfire problems that we now face.
- Phil Zylstra and David Lindenmayer are at the Australian National University's Fenner School of Environment and Society.
