14 December 2017
Andrew Masterson
Andrew Masterson is a former editor of Cosmos.
As wildfires continue to burn through California, and Australia – one of the most fire-prone countries in the world – enters summer, new research suggests that a major blaze-prevention strategy is useless.
Writing in the International Journal of Wildfire, scientists from the School of Biological Sciences at Australia’s University of Tasmania show that “prescribed burning” – the practice of pre-emptively igniting undergrowth prior to fire season – has “only a minimal effect, if any” on the risk and intensity of subsequent bushfires.
Prescribed burning is a standard approach to managing fire risk. The logic is sound – removing underbrush and saplings reduces the amount of fuel available to wildfires – but until now there has been little detailed modelling of how the strategy works in real-world situations.
To remedy this, scientists James Furlaud, Grant Williamson and David Bowman constructed three broad models of fire risk and fire behaviour using Tasmania’s environment and geography. The island state contains large wilderness areas, mountain ranges, deep valleys and a wide array of plant species, both native and introduced.
The team’s first model, the control, posited no fire reduction activity at all. The second, acknowledged as unrealistic, posited maximum prescribed burning, with the strategy used on approximately 30% of Tasmania’s land.
The third, real-world, model comprised 12 scenarios in which only sections of fire-prone environments were burnt. The areas ranged from one to 25% of the total area incorporated in the no-burn and total-burn models, were classified according to vegetation type, and represented a much more realistic modelling of actual fire prevention practice.
The results were discouraging. None of the partial-burn scenarios reduced substantially the predicted likelihood, intensity, duration or spread of subsequent wildfires.
The researchers conclude “our simulation study has shown that realistic, implementable prescribed-burning plans to reduce fine fuel loads … have little potential to substantially reduce the extent and intensity of wildfires at a state-wide scale.”
They urge high priority of other fire mitigation strategies, including using machines rather than fire to reduce underbrush.