Tree Fern Honeymoon

Last week we planted the beautiful “Coin Spotted Tree Fern” Cyathea Cooperi. This week we look again at that species, only this time, it is invasive. Please, don't take your baby tree ferns to Hawaii, they could end up aloha the place...

The "coin spots" on a C. cooperi trunk
https://davesgarden.com/guides/pf/go/55695/Viewed%20on%2029/3/2018
Viewed on 29/03/18
C. cooperi has bright green lacy fronds, but is best know for its “coin spots” where old fronds have broken off from the slender Trunk (Jones, 1980). It can grow 10 - 12 meters and is found along the eastern coast of Australia in humid environments (Large & Braggins, 2004).
C. cooperi distribution
https://www.anbg.gov.au/gnp/interns-2003/cyathea-spp.html
Viewed on 29/03/18
Introduced to Hawaii by gardeners for its fast growth rate (Medeiros et. Al , 1992), this species has been cultivated there since the 1950’s (Durand & Goldstein, 2001).  In the 70’s a feral pig outbreak caused major soil disturbances in many of the native forests, allowing C. cooperi to more quickly establish itself (Medeiros et. Al , 1992). Sadly, our Australian beauty is now a “high risk” registered weed in Hawaii (HISC, 2018) To give you an idea of the scale of this problem, consider the following:  4 or 5  C. cooperi tree ferns were planted along a single Hawaiian road in the 70’s, today you can find hundreds of them growing there (Medeiros et. Al , 1992). As of 1991, there were at least 2000 C. cooperi individuals located in just two squared Kilometers of rainforest (Medeiros et. Al , 1992).
An adult C. cooperi
https://alchetron.com/Cyathea#demo
Viewed on 29/3/18
So what’s the problem? The dense populations of C.cooperi form a thick layer of fibrous roods that smother the forest surface, preventing the establishment of other understory species (Medeiros et. Al , 1992). The ferns establish quickly, growing up to 1 meter per year under the right conditions (Medeiros et. Al , 1992). Furthermore, 10 times as many epiphytes grow on the trunks of native tree ferns compared to C. cooperi (Medeiros et. Al , 1992) resulting in reduced species abundance. If nothing is done, these tree ferns will continue to spread their spores into more forests up to 12km away by wind (HISC, 2018) eventually taking root in every forest on the islands.

What is the moral to the story? You should be careful where you take your tree ferns. They spore like rabbits!





A forest smothered by tree ferns
https://www.fs.fed.us/psw/topics/biocontrol/strawberryguava/native_forests.shtml
Viewed on 29/3/18


Reference List

Durand, L & Goldstein, G 2001, Growth, Leaf Characteristics, and Spore Production in Native and Invasive Tree Ferns in Hawaii, American Fern Journal,  Vol. 91, pp. 25-35

Hawaii Invasive Species Council (HISC) 2018, Viewed 29 March 2018, <https://dlnr.hawaii.gov/hisc/info/invasive-species-profiles/australian-tree-fern/>

Jones, D.L. & Clemesha, S.C.C 1989, Australian Ferns and Fern Allies, The Currawong Press, 2 Aquatic Drive Frenchs Forest NSW 2086

Large, M.F. & Braggins, J.E. 2004, Tree ferns, CSIRO Publishing, Collingwood, Victoria.

Medeiros, A. & Loope, L. & Flynn, T. &  Anderson, S. & Cuddihy, L. & Wilson, K. 1992, Notes on the status of an invasive Australian tree fern (Cyathea cooperi) in Hawaiian rain forest, American Fern Journal, Vol. 82, pp. 27-33

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