Trouble in Paradise: an invasive palm is changing Fiji’s lowland rainforests

The Indonesian ivory cane palm, Pinanga coronata, was introduced to the outskirts of Fiji’s capital Suva in the 1970s. The potential of this species to become an invasive species was first recognised in the early 1990s by Dick Watling, who noticed that the palm had proliferated immensely in a mahogany plantation close to the site of its original introduction.

In 2011, I noticed that it could potentially be disastrous for Fiji’s native species. Walking through the rainforests of Savura Forest Reserve with my friend and colleague Isaac Rounds in search of an endemic tree, we noticed a circle that was 1-3m in diameter and densely covered with small palm seedlings. I realised that this was none of Fiji’s native palms and that no other species were growing in this circle.  Could this spell trouble for the future of Fiji’s rainforests?

In the second half of 2016 Michael Dyer, then an honours student at the University of South Australia, investigated whether the invasive palm affected the abundance of native Fijian tree ferns in both mahogany plantations and rainforests. He found that were the palm was abundant, tree ferns were absent or occurred in low numbers. This has raised strong concerns about the potential consequences of this invasion for native biodiversity. In addition, reports of the palm becoming invasive in other parts of Fiji (near Nadi and on Taveuni) have also surfaced.

A seedling of Pinanga coronata growing on a dead trunk of a native tree fern at Colo-i-Suva, symbolising the threat posed by this invasive palm to Fiji’s native biodiversity

The Fijian NGO NatureFiji-MareqetiViti has now initiated efforts to trial control methods for the palm. In addition, Prof. Hans Juergen Boehmer leads an intensive study and monitoring program of the species in Fiji. While recently published results highlight the importance of these efforts, they also question whether these actions are sufficient and will yield results quickly enough to halt the further spread of this invasive palm.

Further reading:

Dyer MJB, G Keppel, M Tuiwawa, S Vido, HJ Boehmer (2018) Invasive alien palm Pinanga coronata threatens native tree ferns in an oceanic island rainforest. Aust. J. Bot. 66:647-656 (doi: 10.1071/BT18088).

Dyer MJB, G Keppel, MV Tuiwawa, S Vido & HJ Boehmer (2019) Using expert knowledge and field surveys to guide management of an invasive alien palm in a Pacific Island lowland rainforest. Pages 417-422 in Island invasives: scaling up to meet the challenge. Proceedings of the international conference on island invasives, CR Veitch, MN Clout, AR Martin, JC Russell & CJ West (eds.). Occasional Paper of the IUCN Species Survival Commission No. 62. IUCN, Gland, Switzerland.

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