Tasmanian Myrtle Beech Project

About The Tasmanian Myrtle Beech project 

 In 2022, the Inala Jurassic Garden (IJG) was awarded a Botanic Gardens Conservation International/ArbNet grant to undertake a year-long survey of Myrtle Beech (Nothofagus cunninghamii) trees on South Bruny Island, Tasmania in collaboration with the Royal Botanic Gardens Kew, Wakehurst. The focus of the project is to assess if trees are affected by myrtle wilt and to also collect samples to determine if there are genetic differences between the Bruny Island trees and those elsewhere in Tasmania and in Victoria. RBG Kew lead the Global Conservation Consortium (GCC) Nothofagus initiative and this Tasmanian Myrtle Beech project is regarded as a pilot for similar surveys of N. cunninghamii populations throughout is natural range in Tasmania and Victoria.  

Tonia is a proud GCC-Nothofagus Species Steward who has committed to long-term management of the priority Nothofagus species N. cunninghamii which is now listed as Vulnerable on the IUCN Red List due to habitat alteration, invasive species and its susceptibility to Myrtle Wilt disease. 

Myrtle Wilt is a disease of Myrtle Beech, Nothofagus cunninghamii throughout its natural range in Victoria and Tasmania, Australia. The pathogenic fungus, Chalara australis, enters the tree through exposed wounds, invading the sapwood and blocking the tree’s vascular system, causing the tree to wilt and die. Key signs include chlorosis (yellowing) and wilting of the leaves, which then turn bright red-brown, before eventually falling off the tree to expose the naked branches. The presence of the pathogen is often associated with Mountain Pinhole Borer beetles, Platypus subgranosus, which leave behind frass (fine wood dust) around borer holes in the bark. Both the fungus and the beetle are native to South-eastern Australia, restricted to the cooler high-rainfall and high-altitude regions where N. cunninghamii occurs. Myrtle Wilt is often associated with human disturbance like logging or road building and is a major cause of mortality in this species. 

A Myrtle Wilt monitoring program was undertaken by our trusty group of local volunteers within the cool temperate rainforest on Bruny Island, Tasmania in 2023-24. This pilot project was part of a BGCI funded grant in collaboration with Wakehurst, RBG Kew. Although the official BGCI grant has finished, the volunteer Myrtle Wilt survey group have undertaken to conduct annual surveys of the three transects located in the South Bruny Ranges on Bruny Island. The last survey of the 448 N. cunninghamii trees in our three 200 x 20 metre transects was carried out between March-June 2025. During this time six previously healthy trees were recorded as dying and two dying trees had since died. Most of these trees were found in transect 3, which has a high tourist visitation rate.  

This alarming mortality rate within such a small area has caused concern and we are consulting with the Tasmanian Parks Service who manage the land within the survey area on steps to further reduce impact where possible. One action is to recommend that all visitors to this area are required to spray the soles of their shoes with a broad-spectrum disinfectant which is effective against fungi and spores prior to entering the forest trails. 

The group plans to continue our annual surveys, and the next is due in April 2026. I have also been speaking with a variety of people including university students and local community groups to garner interest for a more broad-scale survey throughout the range of Nothofagus cunninghamii in Tasmania. This would be a citizen-science based project involving volunteer members of local communities living in proximity to this species who are passionate about monitoring their local forests. I plan to extend the monitoring program into Victoria to include the whole natural range of this species. 

During this project we also collected genetic material from N. cunninghamii leaves from two sites on Bruny Island (at the base and the summit of Mount Mangana) for sampling with associated voucher herbarium specimens for the Research Centre for Ecosystem Resilience (ReCER) at the Botanic Gardens of Sydney. 2023 was a mast year for N. cunninghamii. This evolutionary strategy, where the species produces an exceptionally high number of flowers and seed en masse in a synchronised event every few years, is thought to aid pollination success and overwhelm predators with a glut of seed over a brief period to enable seedlings to germinate and grow. We also took the opportunity to collect N. cunninghamii seed for the Tasmanian Seed Conservation Centre, at the Royal Tasmanian Botanical Gardens (RTBG) whilst undertaking our survey work in the Bruny Island forests. 

Heartfelt thanks to: 

• BGCI/ArbNet for funding this project. Patricia Malcolm (BGCI) and Sue Paist (ArbNet, Morton Arboretum) provided great support. 

• Olivia Steed-Mundin, Horticultural Taxonomist, RBG Kew-Wakehurst and GCC-Nothofagus Steering Committee member for her encouragement and support throughout the project, for taking the time to personally visit the study sites on Bruny Island after the 7th Global Botanic Garden Congress in Melbourne in 2022 and for her analysis of the data sent to her from our surveys. 

• Most importantly thanks to the following amazing local Bruny Island community members who voluntarily braved leeches and scrambled through thick undergrowth with Tonia to collect the data required for the study: Judy Fakes, Alison van den Berg, Steven ‘Bori’ Morris, James Bunker, David Boyer, Michele Kohout and Ben Convery. 

• Dan Crowley, GCC Coordinator at BGCI for his support and encouragement.