Pacific Island Rainforests and Invasive Alien Plants (IAPs)
Tropical island ecosystems are highly susceptible to biological invasions (see e.g. Kueffer et al. 2010, van Kleunen et al. 2015, Russell et al. 2017). For instance, several introduced plant species have already become dominant in native Pacific rainforests (e.g. Psidium cattleianum and Hedychium gardnerianum in Hawaii´s montane rainforest, see Mueller-Dombois et al. 2013, Minden et al. 2010a, b), thus harming native biodiversity and starting to have considerable socio-economic impact e.g. on forestry and vital ecosystem services provided by forests, e.g. carbon sequestering and freshwater retention (e.g. Boehmer 2011, Keppel et al. 2014).
A new and, regarding its invasiveness, unprecedented example in Fiji´s forests is the ivory cane palm, Pinanga coronata, which is native to Java and Sumatra. There, it is one of the dominant species in its native habitat, which includes steep hillsides in montane forests and flat areas in lowland forests from sea level to 1800 m asl. The palm was brought to Fiji for ornamental purposes in the 1970s where it started spreading in the Colo-i-Suva forest reserve on Fiji´s principal island, Viti Levu.
The palm´s natural tendency to form mono-dominant stands implies that P. coronata can outcompete and displace other understory species. Its invasive potential was first recognized in the early 1990s (Keppel & Watling 2011). Today, it forms dense stands in Mahogany plantations of Colo-i-Suva and spreads rapidly into neighbouring native forests in Savura.
Literature:
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Keppel, G., Morrison, C., Meyer, J.-Y. & H. J. Boehmer (2014): Isolated and vulnerable: the history and future of Pacific Island terrestrial biodiversity. – Pacific Conservation Biology 20(2): 136-145.
Keppel, G. & D. Watling (2011): Ticking time bombs: current and potential future impacts of four invasive plant species on the biodiversity of lowland tropical rainforests in southeast Viti Levu, Fiji. The South Pacific Journal of Natural and Applied Sciences 29 (1), 43-45.
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Minden, V., Jacobi, J. D., Porembski, S. & H. J. Boehmer (2010a): Effects of invasive alien kahili ginger (Hedychium gardnerianum) on native plant species regeneration in a Hawaiian rainforest. – Applied Vegetation Science 13 (1): 5-14.
Minden, V., Henneberg, K. J., Porembski, S. & H. J. Boehmer (2010b): Invasion and management of alien Hedychium gardnerianum (kahili ginger, Zingiberaceae) alter plant species composition of a montane rainforest on the island of Hawai’i. – Plant Ecology 206: 321-333.
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