It’s being called the “Battle for Boranup Forest”, with volunteers needed to help Nature Conservation Margaret River Region survey the extent of invasive arum lilies returning to bushfire-affected Boranup.

In December 2021, wildfire burnt through more than 7800 ha of native vegetation including coastal heath, Karri, Jarrah and Marri forest, much of it around Boranup in the Leeuwin-Naturalist National Park. While the fires wreaked havoc in the forest, the thinned-out understorey presented a unique opportunity for controlling weeds in previously inaccessible areas, and works crews made the most of the opportunity last year.

With arum lilies starting to flower at Boranup, Nature Conservation teams will be returning and assisting the Department of Biodiversity, Conservation and Attractions (DBCA) to survey the extent of the infestation.

“The fire had a massive impact on the forest and the natural vegetation is bouncing back well – but so are the arum lilies,” says Nature Conservation’s Mike Griffiths. “A lot of people are wondering if the fire knocked the arums around, but it didn’t. If anything, it opened up the understorey and created more space for them to get ahead when they would normally have stiff competition from native species.  Arum lilies grow much faster than the shrubs so we need to get in there and make the most of the opportunity before the arums do. We need to carry on with surveying and control as long as we can but the understorey is already starting to thicken and is getting harder to access in some spots.”

Half a dozen volunteers are needed to help survey the arum infestation over two weekdays and two weekends during early spring, with Nature Conservation providing training and equipment. Email mike.griffiths@natureconservation.org.au for more information and to register.

Mr Griffiths said once the surveying is completed, Nature Conservation’s on-ground professional services team and contractors would help spearhead control efforts against the South African weed, alongside DBCA and other groups including the Friends of the Cape to Cape Track (FOCCT). Some of the $9000 raised as part of a GoFundMe campaign by Nature Conservation will be spent on mapping and controlling arums in these areas.

“We know Boranup is a hotspot for arums because of the moisture and sheltered valleys,” says Mr Griffiths. “The forest is a treasured icon of the Margaret River region, it’s popular for camping and with hikers on the Cape to Cape Track, and so we really want to make the most of this opportunity to carry out arum control. If we don’t, they’ll only spread further and do more damage to the forest.”

Friends of the Cape to Cape Track arum coordinator Jenny Kikeros said arums were one of the first plants to reappear after the fire. “They regenerate from rhizomes and seeds, so they were ready to take advantage of the lack of competition,” she says. “But the good news is the fire has made some areas easier to access.” She described Boranup as a “jewel” but said “the forest needs help if it’s going to continue to flourish”. “We can say ‘too hard’ and watch the area lose its diversity before our eyes, or we can stand up and take action.”

Renee Keesing, Blackwood District Officer for DBCA’s Parks and Wildlife Service, said the department has developed a rehabilitation plan for the area including an initial three year weed management program, with arum lilies prioritised “for density mapping, survey of post-fire emergent infestations and targeted control”.

“The lower fuel loads also provide future opportunities to re-introduce prescribed fire under mild conditions and manage fuel loads to reduce the intensity and potential impacts of any future bushfires,” she said. 

Arum lilies outcompete native flora, reduce habitat and food availability for wildlife, and replace native plants with dense monocultures. But collaborative efforts for mapping and spraying within the park, coupled with complementary work on adjacent private land through Nature Conservation’s Arum Lily Blitz, have been reducing arum lily infestations in the Leeuwin-Naturaliste National Park in recent years.

Now in its fifth year, the Blitz involves more than 1600 landholders joining a suite of local on-ground groups like FCCT and government agencies including DBCA controlling arums over more than 20,000 hectares.

Funded by the WA Government’s State Natural Resources Management Program until 2024, the Blitz offers free herbicide, information and resources, while bringing together government agencies, businesses and landholders for coordinated arum lily control. Find out more and register at www.natureconservation.org.au.