Report on the Conservation Status of Norfolk Island Ferns.
[ Internal unpublished report commissioned by and prepared for the Norfolk Island National Park, part of Environment Australia, then as the Australian Nature Conservation Agency. Paper versions of this report can be inspected at the library of Environment Australia and the library of the Australian National Botanic Gardens. ]
J.E.Braggins May 1996
The conservation status and taxonomic status of Norfolk Island ferns is discussed. Eight taxa are endemic and these are the top priority when conservation is considered as Norfolk Island is the only locality where they exist in the wild. Those taxa represented by only one or a few populations in the wild on Norfolk Island are special cases for conservation. These however are found elsewhere and are less important. Specimens of most taxa not held in the ANCA herbarium on Norfolk Island have been collected and labels prepared for them. Where necessary new labels have been prepared for the specimens already held in the collection. Photographs of most taxa have been supplied to ANCA Norfolk Island. Lists of specimens and slides are appended. Several taxa previously collected on Norfolk Island were not relocated during the field work and these are discussed. Species listed as doubtful by Green (1994) were considered and all excluded from lists of Norfolk Island ferns. Several species not previously reported were located some of which appear to be best considered as new native taxa. Others are new adventive taxa and one a possible serious weed. Some taxonomic problems were identified. Distinguishing details to separate both the two treefern species and Nephrolepis species are given. Many of the ferns including all of the endemic taxa are illustrated. Distribution maps are given based on the field investigation. A report on ferns seen on Phillip Island is included.
Norfolk Island is well served for basic information on its ferns the recent Flora of Australia treatment (Oceanic Islands 1 in vol 49) of the islands flora includes ferns and describes 43 taxa of ferns illustrating many of them. Earlier treatments that include ferns include all of the Flora treatments referenced in vol 49 and a few other papers. These are superseded by the Flora of Australia treatment mentioned above.
1.2. Field work.
Many sites were visited on Norfolk Island especially in the National Park but also in some water courses leading from the park. Coastal sites were visited in many areas. Roadsides and ridge sites were also visited. Some taxa appear to be confined to the moister south side of the main peaks. Others are conspicuously coastal or have their main populations on the drier northern slopes. A few were seen at only one locality.
Phillip Island was visited on one occasion allowing a traverse from the eastern end of the island to the normal landing site on the western third of the island.
Specimens were collected to augment the collections held by ANCA (see appendix B) and to provide a research resource for potentially problem taxa. (eg Doodia media and Christella species). The specimens held at ANCA were examined and notes made where redetermination was necessary.
A photographic record was taken of as many taxa as possible and a list of these is appended (Appendix C). These have been labelled and sent to ANCA, Norfolk Island.
2. Conservation status of Norfolk Island ferns.
Taxa of ferns on Norfolk Island can be placed in the following main categories with regard to their current conservation status.
2.1. Taxa not currently at risk, the largest group. This includes taxa that are either widespread in many sites or have well defined habitat preferences and are common in suitable locations. These are marked (1) in the list of individual comments.
In most cases these ferns are not at present threatened, and in some cases it is difficult to believe that they will become threatened in the future. In some other cases species with restricted habitat preferences could become threatened if a change in some major parameter occurred eg a change in water table could affect the stream bank filmy ferns Cephalomanes bauerianum and Crepidomanes endlicherianum.
2.2. Plants known from a limited number of localities but widely scattered and with a limited number of individuals.
These are: Pteris zahlbruckneriana, P. kingiana, Asplenium australasicum f. australasicum, Diplazium assimile, D. australe, Crepidomanes saxifragoides, Lunathyrium japonicum, Vittaria elongata. These are marked (2) in the list of individual comments.
2.3. Plants of restricted distribution - observed in only a few sites,
Pteris vittata, Cheilanthes distans, Lycopodiella cernua, Dicranopteris linearis, Nephrolepis sp., Hypolepis dicksonoides. These are marked (3) in the list of individual comments.
2.4. Taxa not seen in the wild and therefore assumed to be at least as uncommon as those of category 3 In some cases these may be rare or extinct through loss or degradation of habitat.
Asplenium australasicum f. robinsonii, Cheilanthes sieberi, Doodia aspera, Hypolepis tenuifolia, Macrothelypteris torresiana, Ophioglossum petiolatum. These are marked (4) in the list of individual comments.
2.5. Weedy taxa, these include well established native weedy species and also those that have apparently become obvious only recently. New garden escapes will undoubtedly appear in the future to add to this list.
Azolla pinnata, Nephrolepis cordifolia, Platycerium sp., Pteridium esculentum, Salvinia molesta, Selaginella kraussiana. These are marked (5) in the list of individual comments.
2.6. Endemic taxa. These all fit into category 1 or 2 above but because of the small land area (34.6 km2) of Norfolk Island and the limited total population all would automatically fall in the IUCN category of vulnerable and therefore in an international sense are the most endangered ferns on the island. These are marked (1) Endemic or (2) Endemic in the list of individual comments. Some, on population size alone, would be candidates for the endangered category (less than 250 mature individuals in the wild).
Other taxa (those in categories 2.3. and 2.4. ) are much rarer on the island but are found elsewhere. The high international value of the endemic taxa will need to be kept in mind in the development of any management strategies. Any taxonomic decisions in the future that recognise as endemic forms currently thought conspecific with taxa elsewhere may add to the list of endemic species (see Appendix A for list of endemic species).
Most Norfolk Island ferns present no taxonomic problems. A few taxa however present a range of interesting problems . These are given, by species, in alphabetical order.
|3.1||Adiantum pubescens||This taxon as seen in New Zealand has recently been reduced to varietal status in Adiantum hispidulum on the basis that the only consistent difference between them was in hair length. Adiantum hispidulum being the older name has priority. The Norfolk Island plant matches the New Zealand material and should be treated as Adiantum hispidulum var. pubescens (Schkuhr) Large & Braggins. P.S.Green (1994 p564) also comments on the similarity of these two taxa.|
|3.2||Asplenium australasicum forma robinsonii||Plants of this form are held in a number of living collections and apparently though uncommon it was fairly widespread in the past. The plants appear to be sterile hybrids and if they arose a number of times this would explain the variability seen between individuals and widespread distribution of this uncommon plant. In the first instance a study of the spores would indicate if they are sterile or not. One of the potential parents must be Asplenium australasicum f. australasicum and the other must be one of the other aspleniums on the island.|
|3.3||Asplenium difforme/A. dimorphum||Several suggestions have been made for the existence of hybrids between these taxa and some potentially intermediate specimens were observed (at Rocky point). Definitive evidence for hybridisation is however lacking and it is possible that some of the interesting forms seen could have arisen by edaphic variation. There is potential for a study of these based on hybrid analysis and edaphic experimentation such as transplanting experiments.|
|3.4||Christella dentata||All of the many plants examined were consistent in having slow creeping rhizomes and thus differ from the typical expression of this species. They were however not trunked and thus differ from Christella dentata ssp. caespitosa of New Zealand thermal areas and Northern Queensland. The plants show a close match to plants of an as yet undescribed taxon from northern New Zealand.|
|3.5||Christella parasitica||Study is needed on the relationship between the plant found on Norfolk Island and elsewhere in the pacific.|
|3.6||Cyathea australis ssp. norfolkiensis||This species needs comparative work with C. australis on the Australian mainland P.S.Green suggests that it may be distinct at species level.|
|3.7||Doodia aspera||A check on herbarium specimens is needed to check the identity of specimens assigned to this species.|
|3.8||Doodia media||This species shows variable morphology in the field and herbarium material and collections will be checked to confirm that only one taxon is present.|
|3.9||Hypolepis tenuifolia||This species is discussed in Brownsey & Chinnock 1987. It is regarded as rare and easily confused with Hypolepis dicksonoides which is the common Hypolepis on Norfolk. They assign a Backhouse specimen from 1835 and a Sykes specimen from 1971 to this species. The latter seems to be the most recent record for H. tenuifolia. It came from Ball Bay.|
|3.10||Lunathyrium japonicum||Specimens from Norfolk Island need to be compared with the widespread Deparia petersenii as the habitat preference and vigour of the plants is conspicuously different from similar plants treated as Deparia petersenii in New Zealand.|
|3.11||Macrothelypteris torresiana||Material of this species was not found, it may be extinct on Norfolk Island but a locality and identity check is needed of the herbarium specimens that are already held.|
|3.12||Nephrolepis sp. aff.'cordifolia'||The native plant lacks tubers and appears to match New Zealand thermal area plants, for which a specific name has not yet been established. The genus is described as being in need of monographic treatment with the species not well defined by Kramer & Green 1990.|
|3.13||Ophioglossum petiolatum||This species was not seen in the field though some specific localities were checked. It is possibly seriously affected by weed growth in suitable habitats. Earlier specimens need to be checked for localities and identity.|
|3.14||Platycerium sp.||Identity needs checking, may have to wait for mature specimens.|
|3.15||Tmesipteris norfolkiensis||The close similarity of this species to T. lanceolata should be investigated further.|
4.1 Weed problems as they affect the ferns.
4.1.1. Ageratina riparia (William Taylor) this is invading many areas that have populations of smaller ferns and is capable of smothering such species. Populations of ferns noted that were at risk include the only observed colonies of Lycopodiella cernua and Cheilanthes distans as well as one population of Crepidomanes saxifragoides. Ophioglossum petiolatum may have been adversely affected by this weed.
Short term control may have to be by hand weeding as the plants are intermingled with the ferns and spraying would adversely affect the ferns. Hand weeding would have to be carefully supervised as smaller ferns could be damaged or disturbed by the roots of the weed plants as they are removed. Biological control would be a longer term hope but is not yet available though authorities in Hawaii may be developing a suitable control predator.
4.1.2. Selaginella kraussiana is a serious invasive weed and care should be taken to control any infestations as they appear. None were observed in the field though this plant is present on the island.
4.1.3. Red guava (Pisidium cattleianum var. cattleianum) is a serious weed in many sites. Removal of red guava needs to be controlled so that there is not a sudden increase of direct sunlight on ferns and bryophytes which have not previously been exposed as this could cause damage from sun strike etc.
4.1.4. African olive (Olea europea subsp. cuspidata) is a problem similar to red guava. The particular risk is that sun loving ferns become shaded out and lose habitats. One of the ferns particularly at risk in this way is Nephrolepis sp.
5. Forest Restoration activities.
In general the forest restoration efforts ANCA is undertaking at present can only be good for the bulk of ferns in that the amelioration of habitat conditions will encourage the spread of some species as suitable habitats are provided. Also such restoration provides a greater area not affected by weedy species and offers better long term stable habitats.
6. Watercourses/Stream beds.
The lack of flowing water in stream beds in watercourses during my visit was a suprising feature of the forests and it is hoped that this was a temporary phenomenon caused by unseasonable low rainfall. If however this is associated with draw down of ground water and becomes the usual condition then ferns normally associated with watercourses and the associated damp conditions would be at risk.
7. Taxa not previously reported on Norfolk Island.
|7.1||Azolla pinnata||Apparently an omission in earlier treatments, this fern is common in the lower reaches of the Millstream Creek South of the Oval. Whilst it is possible that it was introduced at some stage it is a widespread species and it could possibly be native or have arrived by natural means. For the purposes of management it is probably best to treat it as native. Some local opinion is that it appeared suddenly some 20 or more years ago, and if so and if there is evidence of introduction then it could be considered adventive.|
|7.2||Platycerium sp.||This is planted in several places and in at least one site small plants (c20 in total) are evident on the same and adjacent trees. It is probably best to regard this as a new adventive fern on the Island.|
|7.3||Pteris vittata||This fern occurs as a long established population on the stonework of St Barnabas Chapel (c1880). Plants are clustered thickly at the margins of the front steps and are found in many other similar sites at the base of the building. In addition there are plants established in small cracks in the blocks of the walls, some several metres from the ground. This is a widespread fern in tropical areas and is typically associated with such sites. As many of the individuals are self sown, and it has the capacity to colonise similar sites it can be regarded as established and self perpetuating on the island. An additional plant is present on the stabilised slope behind the administration building confirming its ability to spread.
The problem with this species is whether it was introduced with building materials or if it arrived naturally once such a suitable site was provided. In the second case it would have to be regarded as native, otherwise it can be regarded as an adventive fern. Its specific site requirements and restricted spread over many years suggest that even if adventive it will not become a problem weedy fern.
|7.4||Nephrolepis cordifolia||This aggressive weedy fern is present in several sites and its spread should be monitored and infestations removed where possible. Unfortunately it is similar to and easily confused with the native Nephrolepis which is smaller and less aggressive and lacks the tubers produced by Nephrolepis cordifolia. Confusion between the species and in the naming of the native taxon causes identification problems.|
|7.5||Salvinia molesta||This is present in several privately owned ponds and was reported (Sanderson pers comm.) to be present in Kingston Pond some 15 or more years ago. It is probably best regarded as an adventive and problem weedy species. It is a major weed of still water almost everywhere it occurs.|
|7.6||Dicranopteris linearis||This species occurs only in a single site in one small area on a roadside bank. The site is similar to those it usually occupies elsewhere and it is not necessarily adventive for there is the strong possibility that spores arrived naturally. It seems unlikely that it would be introduced and even less likely to a site such as this. On that basis it may be best treated as native.|
8. Exotic species of ferns as a management problem.
8.1. Most exotic introduced ferns are not closely related to ferns already present on Norfolk Island and therefore can be treated in the same way that other exotic plants are. That is they can be ignored, but their spread monitored, until they appear to present a problem for any native vegetation. A few however that are closely related to local species pose a special problem. These can be confused with the native taxa and may inadvertently be encouraged or spread in ignorance of their true nature. Also eradication is complicated by resemblance to the local species with which they may be confused. For example it would be particularly unfortunate to eliminate a colony of the native Nephrolepis species by mistaking it for the introduced Nephrolepis cordifolia.
An example of a different potential problem is the two native treeferns both endemic to Norfolk Island. These are closely related to other treeferns in the same genus in Australia and could potentially interbreed with other taxa (especially Cyathea australis) should they be introduced. Perhaps the same situation that applies to Araucaria - not growing on Norfolk Island related species, could be applied here. Species of the other main treefern genus Dicksonia would not pose a problem because of their much more distant relationship.
In general the weedy ferns on Norfolk Island do not pose major problems as those regarded as the worst weeds elsewhere are water weeds with little potential habitat on Norfolk Island and most of that is already severely degraded in terms of weed invasion. Even Selaginella kraussiana which can be a problem weed in forests in New Zealand was not observed in the wild on my visit. Thus with vigilance it can be controlled before it becomes fully established in the wild.
This leaves only the Nephrolepis cordifolia mentioned above which is quite widespread (though not observed in the National Park). In general it is still usually associated with gardens and dumps of garden rubbish but apparently it is spreading and it is easily confused with the native species. Therefore I regard it as the main problem exotic fern on Norfolk Island.
9. Individual comments by species.
Comments on the overall status of the ferns on Norfolk Island. Based on a visit of 2 weeks of field work, examination of some herbarium specimens and the available literature. Numbers in brackets refer to conservation categories from section 2.
9.1. Norfolk Island ferns.
|Adiantum diaphanum||(1)||Fairly common in shaded sites. Often forming patches.|
(= A. hispidulum var. pubescens)
|(1)||Common in many exposed sites, usually forming patches which may be extensive.|
|Arachniodes aristata||(1)||Probably the commonest fern on Norfolk Island, usually in shade. May form large patches many square metres in extent.|
|Arthropteris tenella||(1)||A climbing fern found in many sites in forest. Not threatened.|
|Asplenium australasicum f. australasicum||(2)||Widespread but scattered, plants in the National Park are probably safe those elsewhere are endangered by stock and possible over collecting/td>|
|Asplenium australasicum f. robinsonii||(4)||Apparently extinct in the wild a few plants are present in cultivation. Probably of hybrid origin new individuals may appear naturally in the future.|
|Asplenium difforme||(1)||Common in most coastal areas. Adequate sites are in reserves. Not threatened.|
|Asplenium dimorphum||(1) Endemic||Common in forest, widespread on the island. Not threatened.|
|Asplenium polyodon||(1)||Quite common, usually in forest as an epiphyte, widespread.|
|Azolla pinnata||(5)||Only seen at 2 sites but because of specific habitat preference there are few sites that are suitable. Adventive.|
|Blechnum norfolkianum||(1)||Restricted to stream bank sites but in some areas a reasonable number of plants are present (20 + in one case). Vulnerable to a drop in water table.|
|Cephalomanes bauerianium||(1) Endemic||Restricted to stream banks of Broken Bridge Creek and its tributaries, in several areas large numbers of plants are present. Overall probably more vulnerable than Blechnum norfolkianum Only some plants in protected areas.|
|Cheilanthes distans||(3)||Present in small populations on exposed rocks Threatened by invasive woody weeds and Ageratina riparia (William Taylor) its status will need to be monitored.|
|Cheilanthes sieberi||(4)||Not located as living plants, suffers from the same threats as Cheilanthes distans Few reports in recent years.|
|Christella dentata||(1)||Widespread in many sites but not usually in large populations, not threatened.|
|Christella parasitica||(1)||A number of populations are present in a range of sites. Not threatened.|
|Crepidomanes endlicherianum||(1)||Present in and apparently restricted to stream banks of Broken Bridge Creek and its tributaries in several areas large numbers of plants are present.|
|Crepidomanes saxifragoides||(1)||Not common only found in 3 sites but because of its small size it may be more widespread but not observed. Some threat from overgrowth by Ageratina riparia and populations should be monitored. All populations seen are in protected areas.|
|Cyathea australis ssp. norfolkensis||(1) Endemic||Common and widespread, not threatened.|
|Cyathea brownii||(1) Endemic||Common and widespread, not threatened.|
|Dicranopteris linearis||(3)||Only present in one site (see notes 7.6). Threatened, not in a protected area.|
|Diplazium assimile||(2)||Plants scattered but few at any one site. Vulnerable but most populations seen were in protected areas.|
|Diplazium australe||(2)||Scattered records, few at any one site. Vulnerable. Some populations are in protected areas but most seen were not.|
|Doodia aspera||(4)||Not found, old records need checking. There is some doubt as to its existence on Norfolk Island. The possibility of confusion with large specimens of D. media is feasible.|
|Doodia media||(1)||Very common and widespread, not threatened plants variable in size and form.|
|Histiopteris incisa||(1)||Only found twice but populations seem stable. Vulnerable as much because of habitat preference as any other factor.|
|Hypolepis dicksonioides||(3)||Only seen at one site apart from on Phillip Island but as it is a fern of disturbed sites this is not suprising. Vulnerable to change in land use patterns. Described as common on Norfolk by Brownsey & Chinnock 1987 it is still an important colonising fern but not one that persists for long periods in the same locality. It is much less common in 1995 than it was when Chinnock collected in 1971.|
|Hypolepis tenuifolia||(4)||Not seen, a plant of disturbed sites and vulnerable to change in land use. Collected by Sykes, 1971, at Ball Bay.|
|Lastreopsis calantha||(1) Endemic||Seen in several widely scattered sites but individuals are not especially common.|
|Lunathyrium japonicum||(2)||Only seen in a few sites on stream banks, vulnerable.|
|Lycopodiella cernua||(3)||Only seen at one site forming a large patch. Vulnerable to forest regrowth in the long term and to Ageratina riparia invasion in the short term.|
|Macrothelypteris torresiana||(4)||Not seen, may well be extinct on Norfolk Island. Only one old record.|
|Marattia salicina||(1)||Seen at several sites in forest, some regeneration seen, vulnerable to stock and over collecting.|
|Nephrolepis cordifolia||(5)||An aggressive and invasive weed control may need to be considered to protect the native species that is similar in appearance.|
|Nephrolepis sp.||(3)||Only one population seen, also at risk from confusion with Nephrolepis cordifolia see notes (7.4.).|
|Ophioglossum petiolatum||(4)||Not seen, possibly extinct through habitat loss by invasion of weedy species such as Ageratina riparia.|
|Phymatosorus pustulatus||(1)||Common and widespread in many areas. Not endangered.|
|Platycerium sp||(5)||A recent adventive probably not a threat to native taxa and not easily confused with them.|
|Psilotum nudum||(1)||Widespread but not especially common, not endangered.|
|Pteridium esculentum||(5)||Seen in several sites, spreads in disturbed sites. Not endangered.|
|Pteris kingiana||(2) Endemic||Scattered in a number of sites but never with very many individuals. Not endangered but is endemic and should be monitored. Few populations are in the National Park. Most are more or less coastal.|
|Pteris tremula||(1)||In several sites but not especially common. Not as aggressive on Norfolk Island as in New Zealand. Has apparently declined on Phillip Island since 1971.|
|Pteris vittata||(3)||Only seen at 2 sites but well established at one site. Could be lost almost completely if St Barnabas Chapel plants were removed. Vulnerable.|
|Pteris zahlbruckneriana||(2) Endemic||A number of plants in scattered populations in forest at higher elevation. Vulnerable but most of the populations are in protected areas.|
|Pyrrosia confluens||(1)||Common and widespread, not endangered.|
|Salvinia molesta||(5)||One site but reports of a greater range earlier. An aggressive weed, evidence of spread to natural waterways in the future would be a cause for concern.|
|Selaginella kraussiana||(5)||An aggressive weed elsewhere, spread was not observed in the wild. Should it appear in natural areas then this would be cause for concern.|
|Tmesipteris norfolkensis||(1) Endemic||Populations not uncommon at higher elevations, most of these in protected areas, not endangered.|
|Vittaria elongata||(2)||Only a few plants seen this fern should be regarded as vulnerable to disturbance. The populations seen were in protected areas.|
9.2. Excluded Taxa
Regarded as not present on Norfolk Island (Most treated as doubtful by P.S.Green 1994)
|Adiantum fulvum Raoul||(Green p 564)|
|Asplenium oblongifolium Colenso||(Green p 597)|
|Blechnum discolor (G.Forst.) Keys||(Green p 613|
|Davallia pyxidata Cav.||(Green p608)|
|Doodia caudata (Cav.) R.Br.||(Green p 615)|
|Lastreopsis microsora (Endl.) Tindale||(Green p 606)|
|Lindsaea linearis Sw.||(Green p 591)|
|Lycopodium deuterodensum Herter||(Green p 550)|
|Microlepia speluncnae (L.) T.Moore||(Green p 590)|
|Pellaea rotundifolia (G.Forst.) Hook.||(Green p 566)|
|Rumohra adiantiformis (G.Forst.) Ching||(Green p 608)|
10 Key features for difficult taxa
Some species are rather similar to each other and the following notes are included to help differentiate between them
10.1. Cyathea species
|Cyathea brownii||Cyathea australis ssp. norfolkensis|
|This has few fronds, these have very solid bases leaving a few large scars on the trunk for each 10 cm of height.||This has many fronds leaving a series of small scars on the trunk for each 10 cm. of height.|
|The bases fall away cleanly in mature specimens and the trunk becomes very smooth.||The bases usually remain attached to the trunk as a series of short projections (hence the name ‘rough tree fern’).|
|The scales on the stalks of the leaf segments are long and narrow and made up of thick walled cells, dark brown with strong sharp setae all along the sides, the terminal tooth being similar to the others. They are mixed amongst a dense covering of soft pale hairs on mature fronds.||The scales on the stalks of the leaf segments are broadly triangular, soft in texture and made up of relatively thin walled cells with light brown walls. There are irregular soft projections on the sides of the scales but a very different single long dark seta at the tip.|
|Scales on the bases of the fronds and the apex of the plant are often pale but always with strong setose teeth all the way up each side.||Scales at the base of the frond and the crown of the plant are dark brown but still with a single seta at the tip and irregular softer margins.|
|Spores are mid brown.||Spores are yellow.|
10.2. Nephrolepis species
(these are rather difficult to tell apart).
|Nephrolepis sp.||Nephrolepis cordifolia|
|This is the native species and is generally a small plant with few fronds these usually less than 0.5m tall.||This is a robust plant with many fronds to 0.5 m tall or more.|
|Frond dull on the upper surface.||The upper surface of the frond is glossy.|
|The plant usually grows in a scattered colony with the individual crowns rarely crowded closely together.||The plants are large and often grow in crowded colonies.|
|The plants extend the colony by thin runners that root at intervals and establish new crowns.||The plants extend by runners that root at intervals.|
|It does not produce tubers.||Often produces small potato-like tubers covered with scales.|
For most ferns looked at in this survey there is no immediate conservation problem. Even some of those with small populations (Crepidomanes saxifragoides, Vittaria elongata) are present in the National Park and their habitat is protected. Weeds can be a problem for some populations such as Lycopodiella cernua and Cheilanthes distans. However in general the environment in the forest seems to be stable or improving. With the control of rats and exclusion of stock further improvements will follow. In addition as the removal of red guava and replanting programmes proceed improved forest conditions will allow some taxa to expand their geographical range on the island.
The most important group of ferns as far as conservation values are concerned are the endemic taxa. These are Asplenium dimorphum, Cephalomanes bauerianum, Cyathea australis ssp norfolkensis, Cyathea brownii, Lastreopsis calacantha, Pteris kingiana, Pteris zahlbruckneriana and Tmesipteris norfolkiensis. All of these exist as healthy populations or individuals in the wild. All are found in areas that already have legal protection. Some also occur in important populations in areas not currently protected. Cephalomanes bauerianum is a species with good populations outside the National Park. Others such as Cyathea brownii and Cyathea australis ssp norfolkensis and are common and widespread in all suitable areas.
Significant populations of ferns, including endemic ferns, exist in legally unprotected areas and it would be good to see some means of formal agreement to conserve such areas established by local residents and the administration. Such schemes have been successful elsewhere.
A few populations lie outside these parameters. The only known population of Dicranopteris linearis grows on a roadside bank and such sites are difficult to protect. In New Zealand and mainland Australia roadside banks are an area often favoured by weedy fern species and provide a rich habitat resource. On Norfolk Island with many wandering cattle these areas are conspicuously lacking in ferns and the vegetation is usually closely cropped. In addition the prevalence of aggressive weeds such as kikuyu grass creates problems in such sites when grazing is prevented.
I have no simple solution to offer but suggest that local ANCA staff could consider the possibility of fencing a few small areas to observe and document vegetation recovery to provide some baseline data.
Species such as Marattia salicina (King Fern) and Asplenium australasicum are popular garden plants and have in the past been collected in the wild. In some cases this was in the nature of a rescue operation when the particular habitat was threatened. The populations in the National Park though small are apparently stable and perhaps the risk of over-collecting is best dealt with through education.
12. Phillip Island.
A single trip was made to Phillip Island. Few ferns are reported from the island and as the traverse made was on the drier North facing slopes it was not surprising that few ferns were seen. Revegetation appears to be proceeding well despite the large areas of bare soil. As a taller vegetation ameliorates the conditions more ferns can be expected to arrive from sources on Norfolk Island. At present the only ferns noted were Asplenium difforme on the coastal cliffs and Hypolepis dicksonioides in valleys. The Hypolepis is large and has been confused with treeferns in some reports. Not seen was Pteris tremula reported as common by Chinnock in 1971.
Other fern reports from Phillip Island are from the shaded southern cliffs.
The author gratefully acknowledges the significant help provided by ANCA staff based on Norfolk Island especially Margaret Christian, Paul Stevenson, Hugh Yorkston and Derek Greenwood who provided maps, information and access to sites of interest, and discussion of many ideas. Others who provided special help include John Anderson, Ken Cochrane, Owen and Beryl Evans and Duncan Sanderson.
14. Reference list.
Brownsey, P.J. & Chinnock, R.J. 1987. A taxonomic revision of the Australian species of Hypolepis. Journal of the Adelaide Botanical Garden 10: 1-30.
Brownsey, P.J. & Smith-Dodsworth, J.C. 1989. New Zealand ferns and allied plants. Bateman, Auckland.
Endlicher, S.F.L. 1833. Prodromus florae Norfolkicae. F.Beck, Vienna.
Green, P.S. 1994. Oceanic Islands 1. Orchard, A.E. ed. Flora of Australia vol. 49. AGPS Press, Canberra
Large, M.F. & Braggins, J.E. 1993. A morphological assessment of Adiantum hispidulum Swartz and A. pubescens Schkuhr (Adiantaceae:Filicales) in New Zealand. New Zealand Journal of Botany 31: 403-417.
Kramer, K.U. & Green, P.S. 1990. Pteridophytes and gymnosperms. Vol. 1 of Kubitzki, K. ed. The families and genera of vascular plants. Springer-Verlag, Berlin.
|Appendix A||Conservation assessment|
|Appendix B||List of collections of fern specimens|
J = deposited in AKU collection
AN = deposited in ANCA collection.
|Appendix C||List of photographs of ferns|
* = adventive taxon
" = one of two plants on same slide
|Appendix D||Maps of distribution|
In alphabetical order by species, only for those seen in the wild or for specimens collected.
Distribution data for specimens and records for August 1995 trip only.
Common taxa are under-represented and rare taxa over-represented on the maps.
Categories for conservation values for Norfolk Island ferns.
1.1 Native taxa
1.1.1 Endemic taxa
a. endemic species
b. endemic subspecies
2. Habitat conservation status
2.1. Conservancy administered land
2.1.1. stable forest
2.1.2. forest with weed problems
2.1.3. forest with weeds & browsing problems
2.1.4. open land
2.1.5. open land with weed problems
2.2. non-conservancy land
2.2.1. Crown land
188.8.131.52. Management regime actively conserves populations
184.108.40.206. Management regime passively conserves populations
2.2.2. Private land
220.127.116.11. Management regime actively conserves populations
18.104.22.168. Management regime passively conserves populations
3. Major threats
3.1. Weed invasion destroys habitat
3.2. Browsing pressure eliminates population at particular sites
3.3. Modification of habitat eliminates population at a particular site
3.4. Over collecting eliminates population in particular sites
Different taxa are under different types of threat
Some taxa where there are clearly identifiable threats are:
Marattia salicina 2, 4.
Lycopodiella cernua 1,3
Asplenium australasicum var. australasicum 1,4
Cheilanthes distans 1
Diplazium assimile 1
Diplazium australe 1
Dicranopteris linearis 2,3,1
Nephrolepis sp aff cordifolia 3
Endemic taxa should be given a higher conservation status than those that also occur elsewhere where local populations are equivalent. On the basis of IUCN categories any endemic taxa for Norfolk Island would be vulnerable on an international assessment (see 2.6.).
The following taxa are endemic.
|subspecies||Cyathea australis ssp. norfolkensis|
All of these have populations that grow in protected areas and most are common on the island in suitable areas. Some of the best populations of Cephalomanes seen lack protection. Pteris kingiana and Pteris zahlbruckneriana would be the least common of the endemic species in terms of number of individuals. Tmesipteris norfolkiensis is the species with the least area of sites but it occurs in patches representing high numbers of individuals and also is probably present in other valleys not visited.
For areas with significant populations of ferns especially where there are endemic taxa present it is desirable that the area is able to be classified in a positive management category. This may involve no more than regular monitoring but regular checks should be made of some key populations so that baseline data is available to allow the assessment of change. It is clear that changes are taking place, in most cases these appear to be positive changes but different species have different requirements.
List of collections of fern specimens
|Adiantum diaphanum||95/423 J & AN||West Palm Glen Track|
|Adiantum diaphanum||95/443A J||Red Rd. stream bank|
|Adiantum pubescens||95/495 J||E. trib. Broken Bridge Creek|
|Adiantum pubescens||95/481 J||BJ17 Forestry Boundary|
|Arachniodes aristata||95/410 AN||Bridle Track|
|Arachniodes aristata||95/476 J||Near track A52|
|Arachniodes aristata||95/483 J||Dave South's Property|
|Arthropteris tenella||95/409 AN||South of Bridle Track|
|Arthropteris tenella||ANCA 433||West Palm Glen Track|
|Asplenium australasicum (f.a|
|Asplenium australasicum (f.r|
|Asplenium difforme||95/403 J & AN||Culvert, Anson Bay|
|Asplenium dimorphum||95/471 J||Duncombe's Bay Rdnr base of cliffs|
|Asplenium dimorphum||95/484 AN||Dave South's Property|
|Asplenium polyodon||95/416 J & AN||West Palm Glen Track|
|Azolla pinnata||95/401 J & AN||Watermill Ck. S of the Oval|
|Blechnum norfolkianum||95/421 J & AN||West Palm Glen track, streambank|
|Blechnum norfolkianum||ANCA 421||King Fern Valley, streambank|
|Cephalomanes bauerianium||95/431 J||Filmy Fern Valley|
|Cephalomanes bauerianium||95/439 AN||Red Rd, in stream bed|
|Cephalomanes bauerianium||ANCA 429||Lower King Fern Valley|
|Cephalomanes bauerianium||95/490 J||W. trib. Broken Bridge Creek|
|Cephalomanes bauerianium||ANCA 430||Lower King Fern Valley|
|Cheilanthes distans||95/469 AN||Duncombe's Bay Rd, base of cliffs|
|Christella dentata||95/424 J & AN||Officers' Baths, Kingston|
|Christella dentata||95/435 J||Red Rd. on retaining wall|
|Christella dentata||95/438 J||Red Rd. in stream bed|
|Christella dentata||ANCA 430||Ball Bay side of Marshes Rd|
|Christella dentata||ANCA 440||Side of Marshes Rd Ball Bay|
|Christella parasitica||95/447 J & AN||Rocky Pt, lower part of track|
|Christella parasitica||95/482 J||West edge Nat. Pk. peg B64|
|Crepidomanes endlicherianum||95/425 J||Filmy Fern Valley|
|Crepidomanes endlicherianum||95/493 J||W. trib. Broken Bridge Creek|
|Crepidomanes saxifragoides||95/468 J & AN||Duncombe Bay Rd. Base of cliffs|
|Crepidomanes saxifragoides||ANCA 431||Filmy Fern Valley|
|Cyathea australis ssp.n||95/491 J & AN||Mt Bates Track|
|Cyathea australis ssp.n||ANCA 424||Mt Pitt Rd / Mt Bates Track|
|Cyathea brownii||ANCA 425||Mt Pitt Rd / Mt Bates Track|
|Cyathea brownii||95/497 J & AN||Mt Pitt|
|Dicranopteris linearis||95/486 AN||Marshs Rd|
|Diplazium assimile||95/457A AN||Bottom, King Fern Valley|
|Diplazium australe||95/437 J||Red Rd. stream bed|
|Diplazium assimile||95/457B AN||Red Rd. stream bed|
|Doodia media||95/411 AN||South of Bridle Track|
|Doodia media||95/449 J||Bank behind Administration|
|Doodia media||95/467 J||Duncombe Bay Rd cliffs' base|
|Doodia media||95/478 J & AN||Bridle Track opp Cathedral Rock|
|Doodia media||95/485 AN||Dave South's Property|
|Doodia media||ANCA 423||Ball Bay|
|Histiopteris incisa||95/466 AN||Mt Bates Rd|
|Histiopteris incisa||ANCA 426||Mt. Pitt roadside|
|Hypolepis dicksonioides||95/451 AN||Phillip Island|
|Hypolepis dicksonioides||ANCA 427||Phillip Island Red Rd.|
|Lastreopsis calantha||95/419AN||West Palm Glen Track E25|
|Lunathyrium japonicum||95/426 J & AN||Filmy Fern Valley|
|Lunathyrium japonicum||ANCA 441||Lower end King Fern Valley|
|Lycopodiella cernua||95/462 J & AN||Mt Scott 1936 slip site|
|Marattia salicina||ANCA 432||Mt Pitt, roadside|
|Nephrolepis cordifolia *||ANCA 434||Red Rd. trackside nr Mt Bates track|
|Nephrolepis cordifolia *||95/498 AN||Red Rd. trackside nr Mt Bates track|
|Nephrolepis sp.||95/480 J & AN||West edge Nat. Park 51 (BJ17)|
|Phymatosorus pustulatus||95/415 AN||West Palm Glen Track|
|Phymatosorus pustulatus||ANCA 435||West Palm Glen Track|
|Platycerium sp. (bifurcatum?)*||95/465 AN||Natureworld|
|Pteridium esculentum||ANCA 428||Old landslide on Mt Bates|
|Pteris kingiana||95/406 J||N. of Bridle Track|
|Pteris kingiana||95/450 AN||Bumboras Rd|
|Pteris kingiana||ANCA 438||Ball Bay, shaded valley|
|Pteris vittata||95/433 J & AN||Barnabas Chapel|
|Pteris zahlbruckneriana||95/463 J & AN||Nr Mt Scott|
|Pteris zahlbruckneriana||ANCA 439||Achyranthes Valley|
|Pyrrosia confluens||95/475 AN||A52, N side Mt Bates S of Bridle track|
|Pyrrosia confluens||ANCA 436||West Palm Glen Track|
|Salvinia molesta *||95/448 J & AN||Private fish pond Sanderson|
|Selaginella kraussiana *|
|Tmesipteris norfolkensis||95/417 J & AN||West Palm Glen Track|
|Tmesipteris norfolkensis||95/436 J||Red Rd. stream bed|
|Vittaria elongata||95/464 AN||East of Mt Bates Road|
|Vittaria elongata||ANCA 443||Mt Bates Track nr. Mt Pitt Road|
List of photographs of ferns
|Adiantum diaphanum||95.221.11, 23.13|
|Adiantum pubescens||95.25.10 "|
|Arthropteris tenella||95.21.14, 22.2|
|Asplenium australasicum (f.a||95.27.8, 28.18|
|Asplenium australasicum (f.r||95.21.2, 21.4, 21.5|
|Asplenium difforme||95.21.10, 21.11, 25.3, 25.17|
|Asplenium polyodon||95.22.3, 22.19|
|Azolla pinnata||95.20.26, 20.28, 21.1|
|Blechnum norfolkianum||95.23.15, 23.17, 24.11|
|Cephalomanes bauerianium||95.24.7, 24.14, 24.17|
|Christella parasitica||95.21.21, 21.22, 29.4|
|Crepidomanes endlicherianum||95.24.6, 24.15|
|Crepidomanes saxifragoides||95.28.16, 28.17|
|Cyathea australis ssp. n||95.22.22, 27.24|
|Cyathea brownii||95.20.20, 28.7|
|Diplanzium assimile||95.24.10, 27.16|
|Diplazium australe||95.27.17, 29.18|
|Doodia media||95.25.10", 28.15|
|Lycopodiella cernua||95.27.20, 27.21|
|Marattia salicina||95.28.12, 29.25|
|Nephrolepis cordifolia *|
|Phymatosorus pustulatus||95.20.21, 22.16, 22.18|
|Platycerium bifurcatum ? *||95.24.2|
|Psilotum nudum||95.21.16, 23.2 *|
|Pteridium esculentum||95.22.7, 22.9, 22.10|
|Pteris kingiana||95.21.20, 25.14, 25.15|
|Pteris zahlbruckneriana||95.23.14, 27.22|
|Pyrrosia confluens||95.20.19, 23.10|
|Salvinia molesta *|
|Selaginella kraussiana *|
|Tmesipteris norfolkensis||95.22.24, 23.2", 23.3, 23.5, 23.8|
|Vittaria elongata||95.22.20, 27.23|
Maps of distribution
[ To be inserted ]