Cyathea cooperi (australian tree fern)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Cyathea cooperi (Australian tree fern). Habit at Hana Hwy, Maui. March 21, 2007 Copyright ©Forest & Kim Starr Images. CC-BY-3.0	Habit	Cyathea cooperi (Australian tree fern). Habit at Hana Hwy, Maui. March 21, 2007	©Forest & Kim Starr Images. CC-BY-3.0
Title Habit Caption Cyathea cooperi (Australian tree fern). Habit at Piiholo, Maui. April 08, 2009. Copyright ©Forest & Kim Starr Images. CC-BY-3.0	Habit	Cyathea cooperi (Australian tree fern). Habit at Piiholo, Maui. April 08, 2009.	©Forest & Kim Starr Images. CC-BY-3.0
Title Habit Caption Cyathea cooperi (Australian tree fern). Habit at Kulamanu Kula, Maui. December 04, 2006. Copyright ©Forest & Kim Starr Images-2006 - CC-BY-3.0	Habit	Cyathea cooperi (Australian tree fern). Habit at Kulamanu Kula, Maui. December 04, 2006.	©Forest & Kim Starr Images-2006 - CC-BY-3.0
Title Frond detail Caption Cyathea cooperi (Australian tree fern.) Frond at Wailea, Maui. January 24, 2007. Copyright ©Forest & Kim Starr Images-2007. CC-BY-3.0	Frond detail	Cyathea cooperi (Australian tree fern.) Frond at Wailea, Maui. January 24, 2007.	©Forest & Kim Starr Images-2007. CC-BY-3.0
Title Fronds unfurling Caption Cyathea cooperi (Australian tree fern). Fronds unfurling at Wailea, Maui. January 24, 2007 Copyright ©Forest & Kim Starr Images-2007. CC-BY-3.0	Fronds unfurling	Cyathea cooperi (Australian tree fern). Fronds unfurling at Wailea, Maui. January 24, 2007	©Forest & Kim Starr Images-2007. CC-BY-3.0

Identity

Preferred Scientific Name

• Cyathea cooperi (Hook. ex F. Muell.) Domin, 1929

Preferred Common Name

• australian tree fern

Other Scientific Names

• Alsophila cooperi Hook. ex F. Muell.
• Alsophila excelsa var. cooperi (Hook. ex F. Muell) Domin
• Sphaeropteris cooperi (Hook. ex F. Muell.) R. M. Tryon

International Common Names

• English: lacy tree fern

Local Common Names

• English: highland lace; scaly tree fern; straw tree fern
• French: cooper's cyathea; fanjan australien; fougère arborescente d'Australia

Summary of Invasiveness

The Australian tree fern, Cyathea cooperi, is a large treelike fern growing 2-4 m tall. It is native to north-eastern Australia, where it grows in forest margins and open places near the coast. The fern has become well established and invasive on the Hawaiian Islands where it penetrates into undisturbed wet rainforests. It also readily colonizes bare places, landslides and other disturbed places. This tree fern is a fast-growing and large plant with the potential of modifying its habitat and causing harm to the ecosystem. It produces abundant spores dispersed by wind and water, which can reach remote sites far away from planted or already established individuals. The plant can form dense colonies, which ultimately replace native vegetation and threaten species of conservation importance, such as the native tree fern Cibotium glaucum on Hawaii. The species is also listed on the Global Invasive Species Database and is recorded as invasive on Mauritius, where it competes with Cyathea excelsa and Cyathea borbonica.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Pteridophyta
•             Class: Filicopsida
•                 Family: Cyatheaceae
•                     Genus: Cyathea
•                         Species: Cyathea cooperi

Notes on Taxonomy and Nomenclature

Cyathea cooperi, also known as the Australian tree fern, has sometimes been confused with Cyathea australis in earlier works. One of the reasons for this confusion may be because C. cooperi is extremely variable, with some plants having a very large trunk similar to other tree fern species (Jones, 1987). The synonym Sphaeropteris cooperi is still widely used in the literature.

C. cooperi is a popular tree fern grown in gardens and parks. Several cultivars have been developed, such as 'Brentwood' or 'Robusta' (Jones, 1987). The name cooperi honours the British naturalist and curator of the Botanical Society of London, Daniel Cooper (1817-1842). A recent study demonstrated that Highland Lace, a fern with narrow pinnules and relatively small fronds (originally identified as Sphaeropteris tomentosissima) is a cultivar of C. cooperi (Yansura and Hoshizaki, 2012).

Description

The trunk, which is part of the rhizome, reaches 12 m high and may become 15 cm thick. It is covered in oval leaf scars and the lower part is often thickened by numerous adventitious roots. Fronds are 3-4 m long and up to 1 m wide. Frond stalks are up to 50 cm long and have whitish to pale brown basal scales up to 50 mm long and about 5 mm wide. Leaflets are paler underneath and up to 65 cm long, consisting of pinnules up to 12 cm long and up to 2.5 cm wide. They are deeply lobed. Spore cases (sori) are at the forks of veins, roundish and approximately 1 mm across.

Plant Type

Distribution

The fern is native to northeast Australia. It has been introduced and has become an important invasive species on a number of islands including the Hawaiian Islands and on Mauritius. Schäfer (2002) mentions C. cooperi as a most troublesome invasive fern on the Azores, radically modifying its habitat. There are, however, no studies documenting its impact on these islands. On the Azores, the fern is found from 120 to 680 m elevation (Schäfer, 2002). On the Hawaiian island Kauai, the species is found from 550m up to approximately 1400 m elevation on the Alakai Plateau (T. Menard, The Nature Conservancy, Kauai, USA, personal communication, 2013).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

In Hawaii, the fern was reported escaping from cultivation as early as 1950 on the island Oahu (Palmer, 2003). On Maui, it was discovered in 1987 within the borders of Haleakala National Park on the islands east side. In 1991 at least five populations were known, comprising about 2000 individuals and covering over 2 km² (Medeiros et al., 1992). Since this tree fern is available from nurseries and commonly planted, the first naturalized plants may date from before 1987. A population on Kauai, along the Mohihi Road from Waineke Swamp east to Kumuwela road was likely to originate from planted individuals along the road (Medeiros et al., 1992).

In New Zealand, C. cooperi was first observed in 1994 near Auckland (Heenan et al., 1998). In 1998, the plant was known only from one locality under willows near water. Sporelings have also been observed in a nursery near Kerikeri (Heenan et al., 1998). The fern is a naturalized alien in Western Australia, where it is confined to some places between Albany and Perth (FloraBase, 2012). Naturalized populations are also known since 1942 from the Sydney region in south-eastern Australia (Medeiros et al., 1992).

Introductions

Risk of Introduction

Since the fern is a widely used ornamental and available in nurseries, it is likely that plants continue to be introduced into new areas. Heenan et al. (1998) state that the fern has the potential to spread in the north of New Zealand.

Habitat

C. cooperi grows in a number of habitats including forest clearings, gullies and ravines, slopes and streamsides. The fern is mostly confined to lower elevations, but is found up to 1250 m elevation on Hawaii (Durand and Goldstein, 2001a). In Australia, the fern occurs at sites near the coast (McCarthy, 1998). In its native habitat, the fern is a pioneer species, occurring along edges and in light gaps as well as along roads and streams above permanent waterline (Medeiros et al., 1992). As a pioneer species, it establishes especially well after disturbances.

The fern invades mesic forests with the dominant species Acacia koa and Metrosideros polymorpha in Hawaii (Medeiros et al., 1992). Young plants can be found on fallen logs and growing as epipyhtes on other plants (Medeiros et al., 1992). 

Habitat List

Hosts/Species Affected

C. cooperi significantly affects the wild plants Cibotium glaucum, Cyathea excelsa and Cyathea bourbonica through competition and displacement (Medeiros et al., 1992; Chau et al., 2012). 

Biology and Ecology

Genetics

Tindale and Roy (2002) found the basic chromosome number to be n=69, based on a gametophytic count.

Reproductive Biology

As a fern, C. cooperi possesses the typical life cycle with a sporophyte generation and a gametophyte generation. The sporophyte (spore-bearing plant) is the conspicuous fern plant with fronds, roots and stems. It produces spores and its tissues are diploid. A spore germinates and forms a tiny green prothallus, which is the gametophyte (gamete-bearing plant). The prothallus (sporeling) is haploid and has structures on its surface producing the gametes or sex cells, e.g. sperm and egg cells. After fertilization a new sporophyte grows out of the prothallus. Fertilization is in most cases cross-fertilization. This is ensured by the large number of prothalli lying next to each other at a site where spores did germinate.

C. cooperi cannot propagate vegetatively, as it does not produce offsets from the trunk basis or roots (Heydon, 2012). The fern spreads therefore by its spores, which are produced abundantly and dispersed by wind and water.

Physiology and Phenology

C. cooperi is fast growing, with reported annual growth rates ranging from 0.15–1.0 m/y (Medeiros et al., 1992; Durand and Goldstein, 2001a; Schäfer, 2002). A few studies have compared growth and ecophysiological characters of C. cooperi with native tree ferns or native woody plants in Hawaii (Durand and Goldstein, 2001a, b; Allison and Vitousek, 2004; Amatangelo and Vitousek, 2009; Chau et al., 2012). These studies found that leaf litter of C. cooperi contains more nutrients than leaf litter of the native Cibotium glaucum (Table 1), and that litter decomposition rates are faster in the invasive fern than in native species. These results show that the invasive tree fern alters nutrient cycling and nitrogen availability in the soil, affecting the growth of native species.

Table 1. Nutrient contents of the invasive tree fern Cyathea cooperi and the native tree fern Cibotium glaucum on Hawaii. From Chau et al. (2012). Data are means ± SE. 

Frond production in Australian tree fern occurs throughout the year, without showing a seasonal pattern in contrast to native tree ferns in Hawaii (Durand and Goldstein, 2001a). Life span of a frond lasted on average six months on Hawaii (Durand and Goldstein, 2001a).

Overall, C. cooperi grows faster, has a higher rate of photosynthesis, a higher leaf mass per area (LMA) and produces more fronds than native tree ferns in Hawaii (Durand and Goldstein, 2001a,b). These higher values confer a higher competitive ability of the invasive fern.

Population Size and Structure

On the Hawaiian island Kauai, hundreds of young C. cooperi plants have been observed within the Kokee district in 1992 (Medeiros et al., 1992). The same authors noted that the fern occurs with 2000 individuals spreading over an area of 2 km² in Haleakala National Park of Maui.

On Maui, Hawaii, population structure of a naturalized and invasive C. cooperi population was described by Medeiros et al. (1992). This population consisted of 747 individuals within an area of 4800 m². Of these 59% were less than 0.25 m in height, 13% were 0.25-1.0 m in height, 25% were 1.0-3.0 m in height, and 3% were over 3.0 m in height. Two individuals succeeded 4 m height and were estimated to be 6-15 years old. The proportion of fertile plants was determined for 167 randomly chosen plants. Plants less than 0.25 m height were not fertile, and 86% of all plants taller than 1 m were fertile.

Environmental Requirements

C. cooperi grows best in moist to wet and somewhat shady conditions but tolerates drier conditions as well (ISSG, 2012). It also grows in light gaps within its native range, where the fern is as a pioneer species (Medeiros et al., 1992). It does not tolerate waterlogged soils. The plant is a hardy tree fern, Jones and Clemesha (1978) noted that heavy frosts killed the fronds but that the plants quickly recovered. In contrast, Barclay (2012) states that fronds become cold damaged below -3°C and that the species suffers complete mortality at -6°C.

Chlorosis was observed in a frond exposed briefly to air temperatures up to 41°C during expansion (Doley, 1983). Chloroplast development was impaired and chlorophyll concentration dropped to less than 5% of normal. According to the study, expanded and matured fronds were not injured visibly by high temperatures.

Climate

Latitude/Altitude

Soil Tolerances

Soil drainage

• free

Soil reaction

• acid
• neutral

Soil texture

• heavy
• light
• medium

Means of Movement and Dispersal

Natural dispersal (Non-Biotic)

Spores are carried by wind and water. Wind may transport spores 12 km or more (Medeiros et al., 1992). Pig digging creates favourable establishment sites for this disturbance adapted fern (Medeiros et al., 1992).

Vector Transmission (Biotic)

Spores may become attached to mammals and birds, carrying them to new places.

Accidental Introduction

Spores from individuals planted in gardens and along streets are carried by wind into the surrounding vegetation and, after germination, may initialize new populations.

Intentional Introduction

The fern is widely planted and a frequently used ornamental (Jones, 1987).

Pathway Causes

Pathway Vectors

Impact Summary

Environmental Impact

Impact on Habitats

The fern alters nutrient cycling and nutrient dynamics in forest ecosystems in Hawaii. This is because leaf litter quality of C. cooperi markedly differs from that of native species (Chau et al., 2012). The high nitrogen content of the litter of this fern changes growth rates of native species; responses of native species are species specific. In the long-term, species composition may change in invaded areas. It has been postulated that C. cooperi litter may benefit other invasive plant species such as Clidemia hirta, Rhynchospora caduca or Tibouchina herbacea (Welton and Haus, 2008).

Since the plant is a tall tree fern with broad fronds, the underground is shaded. Plant species not adapted to shady conditions cannot grow under Australian tree fern. In addition, a thick layer of fibrous roots accumulates at the soil surface surrounding individuals of the fern, extending up to 5m from a large individual (Medeiros et al., 1992). Such stands almost lack any understory species and cover of bare soil can reach 26%.

Impact on Biodiversity

The fern has been reported to compete with native species on Hawaii, including the native tree fern Cibotium glaucum (Chau et al., 2012). Similarly, it competes with and replaces two native species of Cyathea (C. excelsa and C. borbonica) on Mauritius. The replacement of native tree ferns by this invasive tree fern is of concern because tree ferns are an important component of rainforests on both islands (Medeiros et al., 1992).

In Hawaiian rain forests, trunks of native tree ferns are significant germination and establishment sites for tree, shrub and epiphytic species. This is not the case in C. cooperi. Trunks of native tree ferns harbour more than ten times as many epiphyte individuals compared to trunks of C. cooperi (Medeiros et al., 1992; Medeiros et al., 1993).

Threatened Species

Risk and Impact Factors

Impact mechanisms

• Competition - monopolizing resources
• Competition - shading
• Competition - smothering
• Rapid growth

Impact outcomes

• Ecosystem change/ habitat alteration
• Increases vulnerability to invasions
• Modification of nutrient regime
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species

Invasiveness

• Abundant in its native range
• Fast growing
• Gregarious
• Has high reproductive potential
• Is a habitat generalist
• Long lived
• Pioneering in disturbed areas
• Proved invasive outside its native range
• Tolerant of shade

Likelihood of entry/control

• Difficult to identify/detect as a commodity contaminant
• Highly likely to be transported internationally deliberately

Uses

Economic Value

C. cooperi is a widely used ornamental, planted in gardens and used in landscaping (Jones, 1987).

Uses List

Environmental

• Landscape improvement

General

• Botanical garden/zoo

Ornamental

• Potted plant

Similarities to Other Species/Conditions

Cyathea australis is of similar appearance but grows thicker. The trunk of this species can reach 40 cm in diameter, sometimes even to 1.5 m at the base. Frond stalks of C. australis reach 80 cm long, and the bases are covered with glossy brown scales of 2-5 cm in length. The Hawaiian endemic Cibotium glaucum has no scales but hairs on its frond stalks.

Prevention and Control

Prevention

Pacific Island Ecosystems at Risk (PIER) conducted a risk assessment according to the scheme of Pheloung (1995), see Pheloung (2001). C. cooperi obtained a score of 8, meaning that the species is likely to be of high risk and rejection of importing the plant to Australia is recommended (ISSG, 2012). The fern is, however, native to some parts of Australia.

The fern establishes well in disturbed sites. Thus, there is considerable risk of C. cooperi colonizing newly disturbed sites if spore bearing plants are nearby.

Control

Physical/Mechanical Control

Larger individuals of this species can be felled and their growing tips severed. Smaller plants are best removed entirely (Medeiros et al., 1992). 

Chemical Control

In Hawaii, the herbicide Garlon was used for terrestrial and aerial spraying (Chau et al., 2012). However, this herbicide was found to be relatively ineffective and so The Nature Conservancy switched to using Habitat (Imazapyr) in Kauai. Preliminary analysis has shown Habitat (Imazapyr) to have a success rate of over 95% and combined with using a high-precision, helicopter borne applicator, The Nature Conservancy are currently using a fraction of the herbicide they were using with Garlon (T. Menard, The Nature Conservancy, Kauai, USA, personal communication, 2013).

Gaps in Knowledge/Research Needs

Little is known on the longevity of the spores and under what conditions they germinate. The role of animals dispersing spores also merits further investigation. The current distribution of where the species are invasive is not documented in detail, or this information is not readily available.

References

Allison SD, Vitousek PM, 2004. Rapid nutrient cycling in leaf litter from invasive plants in Hawaii. Oecologia, 141(4):612-619. http://www.springeronline.com/journal/442

Amatangelo KL, Vitousek PM, 2009. Contrasting predictors of fern versus angiosperm decomposition in a common garden. Biotropica, 41(2):154-161. http://www.blackwell-synergy.com/loi/btp

Barclay I, 2012. Cold-Hardy Tree Ferns. Washington, USA: Angelfire. http://www.angelfire.com/bc/eucalyptus/treeferns/cooperi.html

Baret S, Rouget M, Richardson DM, Lavergne C, Egoh B, Dupont J, Strasberg D, 2006. Current distribution and potential extent of the most invasive alien plant species on La Réunion (Indian Ocean, Mascarene islands). Austral Ecology, 31(6):747-758.

Chau MM, Walker LR, Mehltreter K, 2012. An invasive tree fern alters soil and plant nutrient dynamics in Hawaii. Biological Invasions online. DOI 10.1007/s10530-012-0291-0

Doley D, 1983. Chlorosis in a tree fern (Cyathea cooperi) induced by brief heat stress. Australian Journal of Botany, 31:23-33.

Durand LZ, Goldstein G, 2001. Growth, leaf characteristics, and spore production in native and invasive tree ferns in Hawaii. American Fern Journal, 91(1):25-35.

Durand LZ, Goldstein G, 2001. Photosynthesis, photoinhibition, and nitrogen use efficiency in native and invasive tree ferns in Hawaii. Oecologia, 126(3):345-354.

Flora of Australia, 2012. Flora of Australia Online. Canberra, Australia: Department of Sustainability, Environment, Water, Population and Communities. http://www.environment.gov.au/biodiversity/abrs/online-resources/flora/main/

FloraBase, 2012. The Western Australian Flora. Western Australia, Australia: Department of Environment and Conservation. http://florabase.dec.wa.gov.au/

Heenan PB, Breitwieser I, Glenny DS, Lange PJ de, Brownsey PJ, 1998. Checklist of dicotyledons and pteridophytes naturalised or casual in New Zealand: additional records 1994-1996. New Zealand Journal of Botany, 36(2):155-162.

Heydon A, 2012. Cyathea australis, Cyathea cooperi., Australia: Australian National Botanical Gardens. http://www.anbg.gov.au/gnp/interns-2003/cyathea-spp.html

ISSG, 2012. Global Invasive Species Database (GISD). Invasive Species Specialist Group of the IUCN Species Survival Commission. http://www.issg.org/database

Jones DL, 1987. Encyclopaedia of ferns. Portland, Oregon, USA: Timber Press, 450 pp.

Jones DL, Clemesha SC, 1978. Australian Ferns and Fern Allies with Notes on Their Cultivation. Sydney, Australia: A.W. Reed Pty. Ltd, 294 pp.

McCarthy PM, 1998. Flora of Australia. Vol. Ferns, Gymnosperms and Allied Groups [ed. by McCarthy, P. M.]. Melbourne, Australia: ABRS/CSIRO Publishing, 500 pp.

Medeiros AC, Loope LL, Anderson SJ, 1993. Differential colonization by epiphytes on native (Cibotium spp.) and alien (Cyathea cooperi) tree ferns in a Hawaiian rain forest. Selbyana, 14:71-74.

Medeiros AC, Loope LL, Flynn T, Anderson SJ, Cuddihy LW, Wilson KA, 1992. Notes on the status on an invasive Australian tree fern (Cyathea cooperi) in Hawaiian rain forests. American Fern Journal, 82(1):27-33.

Meyer JY, Loope LL, Sheppard A, Munzinger J, Jaffre T, 2006. Les plantes envahissantes et potentiellement envahissantes dans l'archipel neo-caledonien: premiere evaluation et recommendations de gestion. (Les plantes envahissantes et potentiellement envahissantes dans l'archipel neo-caledonien: premiere evaluation et recommendations de gestion.) In: Les especes envahissantes dans l'archipel neo-caledonien [ed. by Beauvais, M. L. \]. Paris, France: IRD Editions, 260 pp.

Palmer DD, 2003. Hawaii's Ferns and Fern Allies. Honolulu, Hawaii, USA: University of Hawaii Press, 324 pp.

Pheloung PC, 2001. Weed risk assessment for plant introductions to Australia. In: Weed risk assessment [ed. by Groves, R. H.\Panetta, F. D.\Virtue, J. G.]. Collingwood, Australia: CSIRO Publishing, 83-92.

Schafer H, 2002. Flora of the Azores. Weikersheim, Germany: Margraf Verlag, 346 pp.

Staples GW, Cowie RH, 2004. Hawai'i's Invasive Species. Honolulu, Hawaii, USA: Mutual Publishing, 114 pp.

Tassin J, Triolo J, Lavergne C, 2007. Ornamental plant invasions in mountain forests of Réunion (Mascarene Archipelago): a status review and management directions. African Journal of Ecology, 45(3):444-447. http://www.blackwell-synergy.com/loi/aje

Tindale MD, Roy SK, 2002. A cytotaxonomic survey of the Pteridophyta of Australia. Australian Systematic Botany, 15:839-937.

Welton P, Haus B, 2008. Vascular plant inventory of Kaapahu, Haleakala National Park, Technical Report 151. Honolulu, Hawaii, USA: Pacific Cooperative Studies Unit, University of Hawaii at Manoa.

Wilson KA, 1996. Alien ferns in Hawaii. Pacific Science, 50(2):127-141.

Wood W, 2008. Subtropical Australian tree fern, Sphaeropteris cooperi (Hook. ex F. Muell.) R. M. Tryon, found modestly established in Oregon. American Fern Journal, 98(2):113-115. http://www.bioone.org/perlserv/?request=get-document&doi=10.1640%2F0002-8444%282008%2998%5B113%3ASATFSC%5D2.0.CO%3B2

Wunderlin RP, Hansen BF, 2012. Atlas of Florida Vascular Plants. Florida, USA: Institute for Systematic Botany, University of South Florida. http://www.florida.plantatlas.usf.edu

Yansura DG, Hoshizaki BJ, 2012. The tree fern Highland Lace is a cultivar of Sphaeropteris cooperi. American Fern Journal, 102(1):69-77. http://www.bioone.org/doi/full/10.1640/0002-8444-102.1.69

Links to Websites

Organisations

New Zealand: Invasive Species Specialist Group, University of Auckland, http://www.issg.org/

Contributors

18/12/12 Original text by:

Ewald Weber, Biodiversity Research, University of Potsdam, Maulbeerallee 1, D-14469 Potsdam, Germany

Distribution Maps

• = Present, no further details
• = Evidence of pathogen
• = Widespread
• = Last reported
• = Localised
• = Presence unconfirmed
• = Confined and subject to quarantine
• = See regional map for distribution within the country
• = Occasional or few reports

Download KML file Download CSV file

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Please click OK to ACCEPT or Cancel to REJECT

OK Cancel

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Please click OK to ACCEPT or Cancel to REJECT

OK Cancel