Rare plant threatened by Cyclone Monica 


Researchers will travel to Arnhem Land this week in search of rare plants that only occur in the area recently decimated by Cyclone Monica.

Department of Natural Resources, Environment and the Arts (NRETA) ecologist Dr David Liddle said that the Arnhem Land Plateau, south of Nabarlek, is the only known location in the world where Boronia viridiflora and Boronia quadrilata exist.

“The cyclone may have severely damaged the only known populations of these plants in one foul swoop,” Dr Liddle said.

“Both Boronia viridiflora and Boronia quadrilata are only known to occur in single, small populations of a few hundred plants.

“Both are shrubs with Boronia viridiflora dangling from cliff faces, and Boronia quadrilata growing upright on sandstone rocky hills.

“There is a good chance the winds of Cyclone Monica will have been particularly damaging to the shrubs growing on exposed cliff faces.

“Both plants were discovered in the early 1990s by botanist Kym Brennan who was conducting field work in the area.

“Many sandstone areas have a high diversity of Boronia species and the populations he found may have survived due to the protected nooks and crannies of this rugged landscape.

“Because of their remote location very little is known about the ecology and population dynamics, so we have been unable to create meaningful management guidelines.

“The Arnhem Land Plateau is a remote and rugged area with few tracks, so we will need to access the plants by helicopter.

“During the survey we also hope to discover the susceptibility or resilience of each species to other threatening processes, such as fire.”

Dr Liddle said the project will create a collaborative association combining the knowledge and expertise of diverse groups and the transfer of skills between these groups.

“To find out more about these relatively unknown species the project will incorporate a study of the seed biology and propagation trials as well as more traditional ecological survey techniques,” he said.

“It is hoped by combining knowledge and searching areas with similar environmental influences we may also find new populations of the Boronia species.

“Local Aboriginal Rangers and staff from the Caring for Country Unit of the Northern Land Council have been involved in establishing the project and will be involved in field assessments of the wild populations.

Charles Darwin University’s Dr Sean Bellairs said that with permission from the traditional owners, samples of the rare plants will be brought back to Darwin to further investigate the factors required for germination.

“Seeds of other Boronia can be difficult to germinate and often need to be specially treated,” Dr Bellairs said.

“We may find that there are special factors required for these rare Boronia.

“These two species are representative of a suite of highly restricted plants occurring on the Arnhem Land Plateau.

“By finding out what these plants require to establish from seed as well as monitoring the wild population we can develop better monitoring programs for the management of numerous other endemic sandstone dwelling species throughout the NT.

“Subject to permission from Traditional Owners, a reserve of generic material and further understanding of the species will also enable us to establish a population at another site should the wild populations decline.”

The Boronia research is a joint initiative by NRETA and CDU, collaborating with the NLC, local Traditional Owners and the Top End Native Plant Society and funded by the National Heritage Trust.