Project studies the best level of Otways burn

THE annual winter planned burns have started across the Otways, but this year, researchers will be studying whether the burns can be beneficial for native plants as well as reducing the risk of wildfire.

Conservation Ecology Centre (CEC) fire ecologist Tamika Farley-Lehmer spent most of November getting to know the plants of the Carlisle Heathahead of this season’s burns by Forest Fire Management Victoria, counting and recording every plant within two metres at 160 different locations to establish a baseline of the number and type of plants.

“All up we counted 69 different species of plants at our sites in the Carlisle, including iconic species such as grass trees and button grass,” Ms Farley-Lehmer said.

“We also made some really interesting observations about how several plants had reacted to past fires.

“For example, a mass flowering of grass trees occurred across the burn scar of a 2020 wildfire, but they weren’t flowering to the same extent within the area burnt by a planned burn in the same year.

“And in a similar vein, we saw rosy hyacinth orchids flowering across the burnt landscape, but not showing the same mass flowering events in areas that were not recently burnt.

“So, what was it about these burns that encouraged the orchids to flower? Why did only the wildfire encourage the grass trees to spring to life? Why were neither species flowering in areas that weren’t burned? Do they need fire to flower? If so, how often? And what do all the other plants and animals that also live there need?”

The observations illustrate how complicated it is to work out what fire regime – in terms of its frequency and intensity – is best for an ecosystem.

Over coming months, the CEC will monitor the response of native plants to several winter burns across the Carlisle, to see whether these burns affect the composition or diversity of species present within the burnt area.

In the long term, the centre hopes to discover whether there is any truth to the hypothesis that winter burns help make the ecosystem healthier and whether these burns also achieve the required level of fuel reduction.

“What we want to know is whether there is a threshold or logical point at which we can successfully manage and reduce fuel loads, while balancing the needs of flora and fauna species,” Ms Farley-Lehmer said.

“For example, only eliminating 40 per cent of fuel hazard rather than 70 per cent, but still reducing the risk of wildfire by 50 per cent and promoting ecosystem function.

“There is no question that these ecosystems need fire, but the question is how much fire, and when, to provide the most benefit both to these ecosystems as well as deliver the fuel reduction and asset protection these programs are intended to achieve.”