By Callum Ludwig
New research published in the Australian Journal of Botany has identified a common plant of the Yarra Ranges that could be wiped from the landscape by more frequent and severe bushfires.
The Hairpin Banksia (Banksia cunninghamii), an upright shrub with rounded orange-yellow and black bottlebrush flowers, has been found to be at risk of extinction in parts of Victoria should it be subjected to bushfires impacting a region within a 12-year span.
Arthur Rylah Institute scientist Annette Muir said populations of Hairpin Banksia in Victoria are declining as climate change drives more frequent, severe and widespread fires.
“ARI has conducted research on the species in East Gippsland following the 2019-2020 wildfires,” she said.
“Results showed the Hairpin Banksia species faced significant challenges to regenerate if fires occur at intervals of less than 12 years apart or if fire severity is high – hindering plants from developing seeds or destroying the seeds.”
The banksia do have a natural regeneration process in the wake of fire, their woody fruits open up when heated by fire and release seeds, but these seeds need around 12 years to mature and produce their own fruit and seeds. Researchers looked at 25 sites burned during Black Summer and only found Hairpin Banksia at sites where the plants were 12 years or older at the time of the fires.
Ms Muir said this research will add to the body of knowledge that supports FFMVic’s approach to planned burning.
“Specialist staff in both fire ecology and threatened species assess each potential burn site for biodiversity values, impacts on ecosystems and develop plans on how to best protect, maintain and enhance their resilience – informing forest fire management activities across the state,” she said.
According to Yarra Ranges Council’s Local Plant Directory, the Hairpin Banskia is ‘locally common within its preferred growing conditions’, preferring to grow in moist well-drained clay soils in open forests with full-sun or semi-shade exposure. They are also tolerant to frost.
Ms Muir said the banksia needs enough time between fires to produce seed but it does vary from site to site and some sites will produce seed earlier than that.
“When you do a survey, you look at many sites and individual sites can vary, and some times areas in the upper Yarra Valley may produce a little sooner than East Gippsland,”
“The important thing is to have a patchwork of different-aged banksias, so then not everything is at risk at once,”
“The East Gippsland fires were unfortunately spread across the whole region and in the Upper Yarra and east of Melbourne, there’s more of a patchwork of different ages which is helpful in maintaining the banksia here,”
Ms Muir also highlighted the positive work of the Montrose Environmental Group in the Yarra Ranges, who have been growing and restoring some Hairpin Banksia plants in areas where they once were, as a positive example of active intervention.
Ms Muir said protecting plants like the hairpin banksia is about caring for more than just the species itself.
“They provide nectar for animals like sugar gliders and honeyeaters, and they flower in autumn so they provide that nectar when there’s not many other things flowering, which I think just points to the fact that keeping diversity in our forests is important,” she said.
“As individuals, fire managers and land managers, we can only have so much influence, as climate change is driving more fire. There are a few years ahead of us (in East Gippsland) before the banksia plants are mature, so another bushfire would cause a severe impact.”
In the research paper, it is suggested that regenerating populations need to be protected from fire during their 12-year interval after a fire, conducting planned burns at appropriate intervals to optimise the levels of regeneration, testing the effects of five severity on the seed cones, a concerted effort to conserve the genetic diversity of the species and considering the possibility of seed banking and restoration planting.
To practically achieve this, the authors of the paper suggest incorporating the hairpin banksia into planned burning operations and taking steps such as locating and mapping the remaining populations, monitoring the maturity of the plants, conducting planned burns when most plants in a population have seed cones and when the weather is not hot and dry to promote germination and survival, increasing the ‘patchiness’ of burns so not all plants in a population are burned at once and ongoing monitoring.
To find out more or read the whole paper, visit: publish.csiro.au/BT/BT24048.
