The Lichens of Stewart Island 1.—THE MOUNT ANGLEM HIGHLANDS

Transactions of the Royal Society of New Zealand : Botany, Volume 3, Issue 16, 16 July 1968, Page 231

The Lichens of Stewart Island I.—THE MOUNT ANGLEM HIGHLANDS

D. J. Galloway

By

Department of Biochemistry, Otago University, New Zealand

[Received by the Editor, September 30, 1966.]

Abstract

The lichen flora of the Mount Anglem region of Stewart Island is described. Recorded species, numbering almost 100, are distributed amongst 19 families and 35 genera. The ecology and distribution of important groups is defined and affinities with the South Island flora are discussed.

Introduction

During his botanical investigation of Stewart Island, Cockayne collected a small number of lichens which he forwarded to Lindau of the Royal Botanical Museum, Berlin, for determination. The resulting published list of fifteen species was arranged alphabetically, with no indication of locality and only brief notes of habitat (Cockayne, 1909a). Since then, no further description of the Stewart Island lichens has been made, with the result that the lichen flora is completely unknown. After Cockayne, several collections from the Freshwater Valley and Herekopere were made by J. Scott-Thompson, and more recently, James Murray collected a few plants from the Pegasus region.

These later specimens are housed in the Otago University Herbarium.

Field work for the present study was carried out in February, 1966, using the Forest Service hut on the west ridge of Mount Anglem as a base. Lichens were collected from the open tops of the northern slopes of the mountain, from the summit plateau, and from its long western ridges which form the greater part of the Upper Freshwater watershed. The open-tops correspond to the alpine herbmoor of Cockayne (1909b), and Wells and Mark (1966). This association is the most easily studied " complete unit" of the lichen flora, owing mainly to the restriction in area of open highlands on Stewart Island, and also because of relative ease of access. The higher plants and bryophytes of this region have been recently described (Wells and Mark, 1966; Scott and Armstrong, 1966) although country west of the summit plateau has not been visited.

Three distinct zones, each with a characteristic lichen flora, can be recognised in the study area:

(1) Subalpine scrub of the northern slopes, 750m-950m.

(2) Exposed summit plateau and western ridge complex, 800m-975m.

(3) Shallow, bog-filled depression on the northern side of Mount Anglem’s highest western outlier, c 950 m.

The Lichen Flora

(I) The Northern Slopes of Mount Anglem, 750m-950m

This zone, which can be designated subalpine scrub, although open areas do occur, is dominated by Olearia colensoi, on the bark of which are occasionally found Psoroma pholidotoides and Menegazzia pertransita. The comparatively rapid growth of Olearia colensoi and the consequent impermanence of its bark is reflected in the paucity of lichen colonisation of this shrub. Lichens as a group are not significant in this locality and, even in open areas, which are generally boggy, lichens are excluded by faster growing sedges and bryophytes. An exception to this is provided by species of the genus Siphula. Deer trails, and areas devoid of vegetation owing to trampling by deer, appear to be reasonably actively colonised by Siphula decumhens, S. fragilis and S. medioxima, together with Baeomyces heteromorphus and several species of Cladonia. Siphula medioxima is the most commonly encountered species and, together with a juvenile form of Baeomyces heteromorphus, occurs widely on drier soil. Siphula fragilis and Siphula decumhens , together with Cladonia foliacea are common in wetter areas and indeed can survive considerable periods of immersion.

(2) Exposed Summit Plateau and Western Ridges

This region probably has a higher rainfall than other parts of the Island, often being under cloud for three days out of five and attracting rain from the south and east as well as from the prevailing westerly. Gold winds from the southern ocean are frequent and sweep over the open tops with considerable force. The erosion of the dioritic and amphibolitic rocks of the area gives rise to ridges which are generally steeper than the more rounded granite surfaces of the southern mountains. This may explain the paucity of lichens on the exposed southern and western slopes and the abundance of saxicolous or terricolous lichens on the more sheltered northern slopes. The principal species in order of abundance are, on the ground; Sphaerophorus tener, Hypogymnia luguhris and Sticta delisea agg., on rock; Pertusaria graphic a forms of Rhizocarpon tinei,* several grey forms of Rhizocarpon and Buellia, and caespitose forms of Stereocaulon colensoi and S. ramulosum. Wind restricts fruticose lichens to Sheltered sites, while foliose plants such as Sticta delisea agg. and the prostrate Hypogymnia luguhris are more successful in colonising exposed sites. The most common terricolous lichen on the open tops is Sphaerophorus tener. This typically fruticose lichen is prostrate in these situations, only rarely fertile and shows extensive evidence of wind damage. On the Table Hill highlands farther south, it is also the most common terricolous lichen. Siphula decumhens is important in the colonisation of wet ground both on the summit and on the western ridges. Just below the summit on the northern side, the typically alpine association comprising Alectoria nigricans, Hypogymnia luguhris and Usnea contexta, is common. This association is also common on the ridge complex several miles west of the summit at an altitude of 850 m, but is absent altogether in very exposed sites. The increase in numbers of H. luguhris and U. contexta can be directly correlated with the decrease in numbers of Sticta delisea agg. Alectoria pubescens and Umhilicaria polyphylla occur occasionally on rocks on the sheltered northern slopes but are absent from other localities.

Two genera which are important components of the South Island alpine flora, viz., Usnea (Neuropogon ) and Thamnolia, are of very limited occurrence indeed in this region, and are absent altogether from the mountains farther south. T. vermicularis is present on the summit (975 m) and also farther west (850 m). Usnea (Neuropogon) is very scarce, the only locality on the Island being the summit rocks of Mount Anglem, where it is restricted to sheltered crevices. The plants are small and are predominantly Neuropogon acromelanus, a few depauperate plants of fertile Neuropogon ciliatus were also collected.

In this area exposed rock outcrops are frequent and support a characteristic flora. Besides the main crustaceous lichens Pertusaria graphica and species of Rhizocarpon, several fruticose forms with well-developed holdfasts are normally present; Usnea contexta and compressed forms of Stereocaulon, S. caespitosum and S. gregarium, offering little resistance to wind. In the shelter of such rock outcrops, a rich growth of lichens is commonly met, species present being: Sphaerophorus tener, varieties of S. melanocarpus, Cladia aggregata, C. sullivanii (including possible hybrid forms of these two species), Sticta flix, S. aurata, Hypogymnia lugubris, Parmelia sulcata, Lepraria incana, Coenogonium nigrum, Stereocaulon colensoi, S. ramulosum, Coccotrema cucurbitula, Pertusaria dactylina and several species of Cladonia and Psoroma. Species of Siphula are common in open grassland, as are Psoroma buchananii, Psoroma hirsutulum and, to a lesser extent, Psora mamilata. In weathered peat at 850 m small, infertile plants of the subantarctic species Thelidea corrugata are present.

(3) Lichens of the Small Cirque Bog

West of Mount Anglem an incipient cirque-like hollow occurs on the north side of the high ridge a short distance west of the large lake. It is much smaller than the other two glacial cirques on the mountain and is less than one hundred feet deep. This depression is bog-filled, and contains several ± permanent tarns. In a discussion of the lichens of this area four ecological zones may be recognised:

(a) Exposed soil.

(b) Wet Sphagnum bog.

(c) Cushion-plant association dominated by Dracophyllum politum.

(d) Open grassland of cirque edge.

(a) Areas of exposed soil (a veneer of peat overlying granite sand, often inundated) are presumably due to the scouring action of surface runoff from the surrounding ridges. There is an absence of typical soil-consolidating lichens, such as Baeomyces and Placopsis, from this locality. In more sheltered situations where movement of water is not vigorous, Siphula decumbens and S. fragilis are common, while S. medioxima is more abundant in drier situations. Siphula appears to play a role in the consolidation of soil in these wetter areas. Species of Siphula characteristically form dense compacted colonies, and it has been suggested (Galloway, 1966) that this genus is important in colonising exposed alpine habitats through the compact nature of its growth, being resistant to fragmentation by strong wind or mechanical abrasion. ', ,

In this cirque bog small tufts of Siphula are common, and are probably resistant relics of formerly larger clumps that have been separated by the action of wind and water. The analogous persistence of Siphula decumbens in damp, deer-trampled soil may also exert some small consolidating effect.

(b) Lichens are absent from areas dominated by Sphagnum .

(c) The most common lichen of the drier cushion-plant association is Sphaerophorous tener, which is typically wind-eroded to a yellow-brown colour and is rarely fertile. Next in order of importance are Hypogymnia lugubris and Sticta delisea agg. Wind-eroded and dead clumps of Dracophyllum politum offer sheltered

sites for lichens and here are found: Siphula medioxima, S. roccellaeformis, Psoroma buchananii, P. sphinctrinum, P. hirsutulum and Pertusaria dactylina.

(d) Lichens are not common elements of the grassland surrounding the bog. Robust forms of Claudia aggregata are most commonly encountered together with

Sphaerophorus tener.

The lichens collected from the Mount Anglem area are listed in Table I. Voucher specimens of the majority of records are deposited in the Otago University Herbarium. The classification used is that of Mattick (1954), with modification. Authorities for specimens quoted in Table I are given in Zahlbruckner (1927), and Lamb (1963) unless otherwise stated.

Discussion

Lichens were collected from the north-facing slopes, the summit plateau and the western ridges of Mount Anglem, Stewart Island. Ninety-five species are recorded, distributed amongst 19 families and 35 genera, in fact a greater number of lichen species occur in this area than do species from higher groups reported by Wells and Mark (1966). Lichens are conspicuous on exposed rocks, where they are more successful as colonisers than bryophytes. On the ground, species of Siphula are important in the colonisation and stabilisation of trampled and wind-eroded areas: S. decumbens is locally common in wet sites. This aspect of ± active lichen colonisation, which is striking in this locality, has been observed in several other alpine regions of the South Island (Murray, 1963; Galloway, 1966).

Comparing the lichens from Mount Anglem with the records published for Secretary Island (Murray, 1963), which is not far distant in Fiordland, enables common features to be seen. In both areas Siphula medioxima and Sphaerophorus tener are the dominant grassland lichens, while a normal lichen of alpine grasslands and tundras, Thamnolia vermicularis, is virtually absent from Secretary Island and Mount Anglem. Sphaerophorus tener is the most wide ranging terricolous lichen on Stewart Island, occurring commonly in grassland on the Table Hill Highlands farther south, besides being a dominant epiphyte (usually in a fertile form) in the Stewart Island forests. Compressed forms of Stereocaulon are common to Secretary Island and Mount Anglem, while the übiquitous yellow and grey biotypes of Rhizocarpon are the dominant saxicolous micro-lichens. Alectoria nigricans and Usnea contexta are locally common on Mount Anglem; U. contexta being widespread on the summit plateau while A. nigricans is common on the ridges farther west. This association, which is typical of many alpine regions in the South Island, is absent from Secretary Island. Cetraria islandica, commonly associated with the above two species, was not found on Stewart Island; this lichen also appears to be absent from alpine localities west of the Main Divide (Galloway, 1966).

A puzzling feature of the lichen flora of this area is the virtual absence of the genus [Usnea) Neuropogon. According to Lamb (1939, 1948, 1964) the centre of distribution of this genus is Antarctic to sub-Antarctic, with associated centres in alpine regions of New Zealand and South America. If one accepts Du Reitz’s assumption (1929) that a genus has originated in the region of its present greatest differentiation, the paucity of Neuropogon on Stewart Island is not readily explained. The occurrence of Thelidea corrugata on Mount Anglem is an interesting extension of the restricted distribution of this plant in New Zealand. Thelidea is a monotypic genus, described by Hue (1901), for plants collected from Campbell Island in 1874. It also occurs in the Auckland Islands and was discovered in New Zealand in the Awarua peat bogs (Martin, 1960). Plants typically occur in sub-alpine peat bogs and have been collected from the Rakeahua flats on Stewart Island and from Mount Maungatua, Swampy Hill and Silver Peaks in the Dunedin botanical district.

It is likely that many of the lichen genera in the New Zealand flora are of Antarctic origin and the existence of such genera as ( Usnea ) Neuropogon, Menegazzia, Thelidea and Sphaerophorus would indicate this. Claims for the Antarctic origin of the New Zealand lichen flora would be further enhanced by the discovery of Stereocaulon argus and Argopsis megalospora, species known to occur on the Auckland and Campbell Islands, but not yet recorded from New Zealand.

Acknowledgments

The author wishes to thank D. M. M. Macarthur, N.Z.F.S. Ranger, Stewart Island, for much helpful assistance during the course of these investigations, H. Hansen of Oban for transport to Christmas Village and A. F. Mark and G. A. M. Scott for acccess to unpublished results.

Literature Cited

Cockayne, L., 1909a. List of lichens collected in Stewart Island during the Botanical Survey of 1908. Trans. N.Z. Inst., 42: 320.

Du Rietz, G. E. (1929). The discovery of an Arctic element in the lichen flora of New Zealand and its phytogeographical consequence. Rep. Aus. Ass. Adv. Sci. Hobart. 19: 228.

Galloway, D. J., 1966. Vegetation studies on the Humboldt Mountains, Fiordland. 2. The Lichens. Proc. N.Z. Ecol. Soc., 13: 19.

Hue, A. M., 1901. Bull. Bot. Soc. France XLVIII, 61.

Lamb, I. M., 1939. A review of the genus Neuropogon (Nees and Plot.) Nyl., with special reference to the Antarctic species. J. Linn. Soc. {Bot.), 52: 199.

1948. Further data on the genus Neuropogon. Lilloa, 14: 139.

1963. Index Nominum Lichenum. New York.

Cornicularia. Brit, Antarctic Survey Rep., 38.

Martin, W., 1960. The cryptogamic flora of the Awarua Plains. Trans. R. Soc. N.Z., 88: 161.

Mattick, F., 1954. Syllabus Der Pflanzenfamilien. XIII Flechten. Band I, Berlin

Murray, J., 1963. Vegetation studies on Secretary Island, Fiordland. Part 7: Bryophytes and lichens. N.Z. Jl Bot., 1: 221.

Runemark, H. (1956). Studies in Rhizocarpon. 1. Taxonomy of the yellow species in Europe. Opera Botanica. Lund.

Scott, G. A. M.; Armstrong, J. M., 1966. The altitudinal sequence of climax vegetation on Mount Anglem, Stewart Island. Part 2. Ground and epiphytic vegetation. N.Z. Jl Bot., 4: 283.

Wells, J. A.; Mark, A. F., 1966. The altitudinal sequence of climax vegetation on Mount Anglem, Stewart Island. Part 1. The principal strata. N.Z. Jl Bot., 4: 267.

Zahlbruckner, A., 1927. Catalogus Lichenum Universalis.

D. J. Galloway, Department of Biochemistry, University of Otago, Dunedin.

•Formerly regarded as the polymorphic species R. geographicum. According to Runemark, (1956), this taxon is a nomen ambiguum and further work on the New Zealand species in the light of his research is warranted.

A list of lichens collected from the Mount Anglem region of Stewart Island. e Mount Anglem region of Stewart Island.Substrate Substrate and abundance are given for each species as follows: follows: Abundance Scale Substrate r = rare R = rock o = occasional S = soil f = frequent B = bark a = abundant LIGHENES IMPERFECTI C. fimbriata S.o Lepraria incana R.r C. foliacea Si Siphula decumbens R.r . S.o C. foliacea S.f C. leptoclada S.o S. dissoluta ... S.o C. pyxidata ..: S.o S. fragilis .. S.o C. scabriuscula S.o S. medioxima .. S.a C. verticillata S.o S. roccellaeformis ... S.f Clathrinaceae Thamnolia vermicularis ..S.r Cladia aggregata ..., Thamnolia vermicularis S.f ... S.r S.f SERIES CONIOCARPINEAE C. retipora C. sullivanii S.o S.o Fam. Sphaerophoraceae Stereocaulaceae Sphaerophorus melanocarpus var. Stereocaulon caespitosum R.f australis Stereocaulon caespitosum R.f . Bo S. colensoi R.o Sphaerophorus tener ... S.a S. corticatulum var. humile R.o S. gregarium R.f SERIES GYCLOCARPINEAE S. ramulosum R.f Umbilicariaceae Thelotrema lepadinum ... S.r Umbilicaria cylindrica R.o Goenogoniaceae U. polyphylla R.o Coenogonium nigrum R.o Acarosporaceae Pannariaceae Acarospora fuscata R.o Pannaria granulifera ... B.r Pertusariaceae P. immixta ... B.r Pertusaria dactylina S, B.o Parmeliella amphibola .. B.r P. superba R.o P. nigrocincta . B.o P. graphica R.a . Psoroma arthroophyllum .'. . B.o P. basaltica R.o P. buchananii ......'. .. S.o Lecanoraceae P. hirsutulum , S.o . S.o Lecanoraceae P. leprolomum . B.o Lecanora atra R, B.o P. pholidotoides ... B.o L. blanda R.o P. sphinctrinum : B. , R.o Placopsis parrelina R.o Thelidea corrugata .. S.r P. perrugosa R.o Stictaceae P. rhodophthalma : R.o Ochrolechia parella R.r Sticta aurata . R.o O. tartarea R.r S. aurigera R.o Candelariella vitellina R.o S. delisea agg S. endocrysea .. S.a ... S.f Parmeliaceae S. filix : . S.o P. adpicta R.r S. flavicans . S.o P. caperata R.o S. freycinetii ... S.o P. conspersa R.o S. limbata . S.o P. perlata : R, B.o S mougeotiana .. S.o P. sulcata R.o Peltigeraceae Hypogymnia lugubris Menegazzia circumsorediata S.a B.f Peltigera canina ... S.r M. dense B.o P. polydactyla .. S.r M. pertransita R, B.f Lecideaceae Usneaceae Lecidea irrubens R.o Alectoria nigricans S.o L. fuscoatra R.o A. pubescens R.r Psora mammilata . S.o Usnea arida R.f Rhizocarpon (geographicum group U. contexta R.S.f several spp.) „. R.a Usnea arida R.f Rhizocarport (geographicum group U. contexta R.S.f several spp.) Usnea (Neuropogon) acromelanus R.r T"> 1 , R.a Usnea (Neuropogon) acromelanus R.r R. grande :. R. tinei . R.a R.a Usnea {Neuropogon) ciliatus ... Buelliaceae R.r Gladoniaceae Buellia canescens S.r Baeomyces absolutus ..'. R.o B. melaxanthella S.r : B. heteromorphus . S.o Rinodina thiomela R.o Cladonia chlorophaea ... S.o C. coccifera .. S.o Physciaceae C. coniocraea ;.. .. S.o Physcia caesia R.r C. cornutoradiata .. S.o P. stellaris „ R.o

Table I