News release

From: Queensland University of Technology (QUT)

Land clearing linked to myrtle rust disease in native forests

New research has revealed past land clearing is increasing the vulnerability of native Australian forests to the invasive myrtle rust disease — with regrowth forests emerging as hotspots for impact.

In a study published today in the journal Ecological Solutions and Evidence - Historical land use couples with host density to affect myrtle rust impacts in a wet sclerophyll forest community in Eastern Australia - researchers surveyed 21 patches of eucalypt rainforest (wet sclerophyll forest) across Queensland and northern New South Wales. The site species included the small bushy native rainforest Myrtaceae (the myrtle family), that are susceptible to myrtle rust.

Among the national park, council and privately owned land examined were areas that had been subject to different levels of historical land clearing (i.e., level of canopy cover in the 1960’s).

Led by Dr Kristy Stevenson and Professor Jennifer Firn at QUT, the National Environmental Science Program Resilient Landscape Hub study found this type of forest with a history of heavier land clearing was more impacted by myrtle rust.

“Regrowth forests tend to have higher densities of species that are highly susceptible to myrtle rust, particularly a small tree called rose myrtle (Archirhodomyrtus beckleri),” Dr Stevenson explained.

“Native rose myrtle can rapidly recover and dominate an area after land clearing. However, its abundance is also associated with more severe myrtle rust damage at those sites.

“Our results show historical land-use leaves a biological legacy that can shape disease risk decades later.

“It’s not just where the pathogen can go - it’s where the most vulnerable hosts are concentrated.”

Professor Firn added that the findings had important implications for forest management and conservation planning.

“Regrowth forests may need closer monitoring for both myrtle rust damage and weed invasion, while less disturbed areas could act as important refuges for healthier individuals of threatened species, with value for long-term conservation and potential plant breeding,” Professor Firn said.

“Mapping clearing history alongside forest age could help managers target surveillance and management where disease risk is highest.”

Myrtle rust is caused by the highly destructive fungal pathogen Austropuccinia psidii. Native to south America, it was first detected in Australia in 2010 and has since spread rapidly. It is a wind-dispersed disease threatening a wide range of native eucalypts, tea trees and bottle brushes. As its spores travel easily across landscapes, understanding where susceptible plants occur is critical to slowing its spread and damage.

Read the full paper online: Historical land use couples with host density to affect myrtle rust impacts in a wet sclerophyll forest community in Eastern Australia

• The Resilient Landscapes Hub provides research to support the management of Australia's terrestrial and freshwater ecosystems, improving their resilience to extreme events and pressures including bushfires, droughts, floods, and invasive species. The Hub is funded by the Australian Government under the National Environmental Science Program.