He says due to the changing climate, predicting fuel moisture – the amount of water held in dead plant material – will become an ever important tool for fire managers when predicting fire danger and behaviour.
Using computer models, Matthews and colleagues estimated how much water is held in dead plant matter in areas around Sydney, Brisbane, Canberra, Hobart and Melbourne.
They then combined the results with a climate model to predict fuel moisture between 1961 and 2100.
Matthews and colleagues also collected fuel samples from the field over several years that confirm the fuel moisture model was correct.
He says the climate model projected weather conditions from now into the future in a high emissions scenario.
Less time to prepare
The results of the study show opportunities for prescribed burning in spring will decrease in warmer and drier years.
“Prescribed burning is done during the transition from fuel being wet and soggy in winter to dry in summer,” he says.
But in warmer years Matthews says the fuel dries out faster.
“And if the fuel is too dry then the fire will be too intense and difficult to manage,” he says.
Matthews says this is a concern for prescribed burning in areas like rural Victoria, the location of February’s ‘Black Saturday’ bushfires, which contain a high number of stringy-bark eucalypt trees.
“They’re notoriously difficult because they have a lot of loose fibrous bark that cause spot fires and they may be on the wrong side of the control line.”
Matthews says although there are variations in fuel moisture from year to year, “we’re looking at things being drier more frequently.”
“If the climate continues to warm and dry as we expect they’ll be more days when wildfires can occur and a greater proportion of those days will have drier fuel moisture.”
Matthews says the next step will be to look at fire moisture levels in regional areas around the country.
“I’m planning to look in more detail at the results we’ve got to see if it’s possible to do some prescribed burning in winter,” he says.