Burning banksias to save them
Banksias are an iconic species that play an important role in fire prone ecosystems across South Australia. Many native species of birds, insects and mammals, including vulnerable pygmy possums feed on the nectar and pollen of banksias. Without this nectar some of these species would no longer be able to call this ecosystem their home.
So, when our ecologists saw dead mounds of banksia at Cox Scrub and Newland Head conservation parks on the Fleurieu Peninsula they investigated options to reinvigorate the ecosystem. Their aim was to maintain suitable habitat for vulnerable fauna by giving the banksias and other fire adapted plants a chance to regenerate before it was too late.
The relationship between when an area last burnt, how big that fire was, what time of year it occurred and how intensely it burned all form part of what we call the fire regime, and maintaining a healthy fire regime is critical for banksia habitats.
Many banksias are ‘serotinous obligate seeders’, which means they are killed by fire but also require it to persist in the ecosystem. Fire helps to crack open their woody seed pods to release seed which can then germinate in soil enriched with ash.
Fire that is too frequent can also be an issue. Banksia stands can be seriously impacted if a second fire occurs before new seedlings have time to mature and establish a large enough seed bank. This is where fire planning is critical in getting the timing right. Prescribed burns are preferably timed to burn banksia stands before they become old and die whilst allowing recently burnt stands to establish themselves in the landscape.
In addition to using fire to manage banksia regeneration and habitat health on the Fleurieu Peninsula, a control program was put in place by regional staff to decrease grazing pressure on the plants which helped new seedlings reach maturity without being eaten.
The importance of monitoring
To support prescribed burn planning we use monitoring at key sites both before and after burns. In one of these burns at Newland Head, which included very large areas of old and dying banksia, we measured significant improvement. Within only 2 years we had a measured increase in banksia cover at the burn site and we also recorded an increase in distribution across the site.
Monitoring results 4 years post burn: Banksia ornata increased from being found in 12 survey sites before the 2020 burn to being found in 20 sites in 2024. Plant cover also doubled and will only increase as the plants mature. Up to 40% of new individuals have already flowered following the fire. The monitoring also showed a decrease in the number of plants that were severely impacted by grazing.
This demonstrates the importance of fire, and how active management is sometimes needed to maintain key species for the benefit of vulnerable fauna such as pygmy possums and threatened birds. It’s important to maintain and support a healthy fire regime so that key species such as banksia and the species that rely on them are better able to regenerate when things don’t go to plan and landscapes are impacted by large scale intense bushfires.
