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Tuatara: Volume 17, Issue 1, May 1969

New Zealand Lichens and their Habitats

page 20

New Zealand Lichens and their Habitats

Lichens are able to colonize almost any surface not permanently covered by water, ice or snow; and as many can endure extremes of heat or of cold that would prove fatal to other plants, they are to be found in all latitudes and at all elevations. Since they require little or no nourishment from the substrate they usually occupy such sterile substrates as rock, wood, bark, leaves, heath and peat soils, bricks, tiles, and even asphalt, where they have no competition with other plant types. Nevertheless most lichens are restricted to a single type of substrate, though others less fastidious may occupy two or more. Similarly some species are found only at one altitudinal level such as lowland, montane, subalpine, or alpine, while others range over two or more such zones. The only species known to occur from sea level to 9,000 feet is Stereocaulon corticatulum.

New Zealand covers the twelve degrees of south latitude between 35° and 47°, and has an altitudinal range of 12,000 feet, while the annual rainfall ranges from about twelve inches in some areas to as much as 250 inches in others. As a result there is a very wide range of ecological conditions reflected in an extensive lichen flora of possibly 1400 species.

Of these indigenous species about 20% occur north of the equator, some of which are in fact cosmopolitan. There is also a strong endemic element with some species ranging the greater part of the Dominion and others confined to localised areas such as North Auckland or Otago and Southland. Species such as Cladia retipora, C. sullivanii, or Chondropsis semiviridis are restricted to Australasia while others like Neuropogon spp., Stereocaulon argus, or Thelidia splachnirima belong to a subantarctic element. Some 200 species are common to New Zealand and Tasmania and a large number including many species of Cladonia, Menegazzia, Placopsis, Pseudocyphellaria, and Psoroma are indigenous both to New Zealand and Southern South America. A subalpine association met with both in this country and in Britain comprises Alectoria minuscula, A. nigricans, Cetraria islandica, Cornicularia aculeata and Solorina crocea.

A number of lichens are found only on coastal rocks, some are confined to subalpine habitats, and some to alpine rocks, but a majority of species, especially the epiphytic, belong to the lowland and montane area. The transition from subtropical rain forests to subantarctic beech forest takes place at approximately 2,000 feet, but page 21 the associated lichens are not conspicuously different until the subalpine shrub zone is entered. The alpine zone commences at different levels according to the latitude and prevailing climatic conditions, but 6,000 feet may be taken as an arbitrary base for this upper zone. Subalpine lichens belong mainly to the following genera:— Alectoria, Agyrophora, Cetraria, Cladia, Cladonia, Dermatocarpon, Diploschistes, Hypogymnia, Lecanora, Lecidea, Neuropogon, Omphalodiscus, Pannaria, Parmelia, Parmeliella, Pertusaria, Pseudocyphellaria, Porina, Ramalina, Rhizopogon, Rinodina, Siphula, Solorina, Stereocaulon, Thamnolia, Umbilicaria and Usnea.

Relatively few collections of alpine lichens have been made. On Mt. Tapuaenuku in Marlborough (9,400 ft.), there is no permanent snowline, but on rocks between 7,000 feet and the summit J. Scott Thomson collected the following typical saxicolous lichens:— Alectoria pubescens var. reticulata, Agyrophora zahlbruckneri, Caloplaca elegans, Neuropogon acromelanus, N. ciliata, N. antarctica, Omphalodiscus subaprina, Stereocaulon corticatulum, and Umbilicaria cylindrica. Neuropogon acromelanus has also been collected at 7,500 feet on Mt. Aspiring and on several other peaks; and on rocks near the summit of Mt. Tutuko (9,000 ft) in Fiordland, Scott Thomson has collected Rhizocarpon geographicum and one species each of Anaptychia, Buellia and Umbilicaria. Other lichens from rocks above 6,000 feet include Agrophora leiocarpa, Cetraria islandica, C. novae-zealandiae, Lecanora endorhodia, Parmelia adpicta, P. otagensis and Umbilicaria deusta.

There is much diversity among lichens in regard to their tolerance of shade intensity. The deeper the degree of shade within the forest the fewer the lichens present both of species and of individuals. For the same reason the lichens of the forest canopy differ from those on the lower trunks. However in Central Otago, the lichens on the southern or shady side of tall rock stacks far outnumber those on the sunny northern face but for different reasons. Lichens thrive best when moist and dry conditions follow in quick succession; hence, in areas both of scanty or of excessive rainfall the lichen flora tends to diminish. Foliose lichens thrive best and attain their maximum size in the calm, moist conditions of the forest interior, but fruticose and crustose species are most numerous on substrates exposed to full daylight. The only foliose lichens in alpine stations are small, black members of the family Umbilicariaceae.

Characteristic Lichens of Various Substrates

1. Coastal Rocks

Coastal rocks and cliffs support a copious and varied lichen vegetation some species being restricted to this station, some most page 22 common on maritime rocks, and others equally common on other lowland rocks. At the lowest level are a number of widely distributed, small, gelatinous lichens confined to intertidal stations as Lichina pygmaea var. intermedia, Arthopyrenia halodytes or A. balanophila—the two last named found only on the valves of barnacles stationed on the rock. Encrusting rocks and boulders from just below high tide levels to some distance above, the black thalli of V errucaria maura are common on many rocky coasts. Cliff faces below the lowest level of shrubs and herbs have as the dominant lichens other species of Verrucaria such as V. adguttata and V. aucklandica in the North Island or V. lacrimans and V. otagensis on the Otago coasts. The genus Placopsis, especially on volcanic rocks, is also common — P. gelida, P. parellina, P. perrugosa, P. trachyderma, and P. rhodophthalma, all being present.

Coastal rocks beyond the spray zone are frequently encrusted with extensive patches of the golden or reddish Xanthoria parietina, a species of wide distribution in similar stations overseas. Caloplaca has a number of coastal species such as C. archeila, C. acarocarpa and C. circumlutosa but much the most attractive species is C. etesiae. Though not restricted to coastal rocks Pertusaria graphica is the commonest and most widespread of six or seven coastal species. Other coastal lichens include many crustose species of Lecanora, Lecidea and Buellia, also Opegrapha sp. and Enterographa neozelandicum. Rinodina exigua and R. thiomela occur locally. Fruticose lichens are represented on coastal cliffs by Ramalina arabum and R. angulosa in the north and R. scopulorum in the south.

2. Calcareous Rocks

As in the previous station some lichens are restricted to the substrate and others occur elsewhere as well. The following species are wholly or almost wholly so restricted: —Caloplaca blastenioides, C. murorum, C. pyracea, and C. Thomsoni; Blastenia alboflavida, Lecanora jertilissima, L. pulvinaris, Leptogium plicatile, Placynthium nigrum, Porina rhodinula, Thelidium neozelandicum and Toninia tumidula. Other common lichens on calcareous rocks but not restricted to them include Bacidia subcerina, Buellia epipolium, Pannaria nebulosa, Parmeliella microphylla, Parmelia epheboides, P. perlata all but the last being crustose species. Physcia caesia is to be seen on limestone but occurs on rocks of all kinds. The coastal Verrucaria otagensis may be confined to calcareous sandstone but this needs verification.

3. Schist Rocks

The majority of mountain ranges in New Zealand are composed of metamorphic rocks such as greywacke or schist, but there are hundreds of square miles of mountainous country as yet unexplored in respect to the lichen flora especially at the upper subalpine and page 23 alpine levels. The following notes deal only with the better known schist rocks of central, east, and north Otago. Rising above the normal ground level are large rock mounds, stacks, and tors which on their southern sides have a copious lichen cover, but a very meagre lichen population on the sun-baked northern side. This is due in part to the south and east dip of the rock strata presenting a flat surface on the shady side, but a very irregular surface formed of the edges of the rock layers on the sunny side. A further reason is that the rain-bearing winds are mainly from the south, and the rocks also dry more rapidly on the sunny faces. As much as 90% of the surface may be covered with lichens on the southern side and only one or two per cent on the north.

Flat tops and southern faces of montane rocks bear Parmelia spp., Lecanora blanda, L. atra, Pertusaria subverrucosa, Rhizocarpon geographicum, Umbilicaria polyphylla, and Usnea glomerata; and near the base Pseudocyphellaria mougeotina, Coccocarpia cronia and Teloschistes jasciculatus. Common Parmelias are P. arnoldii, P. caperata, P. conspersa, P. perlata. P. prolixa, P. rudecta, P. rutidota and P. tasmanica and more locally P. epheboides, P. petriseda and P. waiporiensis. In rock crevices Cladonia capitellata, C. fimbriata and Cladia aggregata are occasionally present. The common species on the northern side are Anaptychia spp., Heppia guepinii, Physcia caesia and Caloplaca spp.

At subalpine levels the following saxicolous lichens occur on Mt. Maungatua—Lecanora blanda, Lecidea confluens, L. schistiseda, Placopsis perrugosa, Rhizocarpon grande, Stereocaulon corticatulum, S. ramulosum and the dwarf S. caespitosum all at 3,000 ft. as well as Umbilicaria vellea and Usnea torulosa. On the Kakanui Range Cetraria pubescens, Neuropogon ciliata, Parmelia mougeotina, Umbilicaria corrugata, and U. cylindrica are present at 5,000 ft., and on Mt. Ida U. decussata, U. hyperborea and Omphalodiscus subaprinus.

4. Other Rocks

Without further research it is not possible to say which lichens if any are restricted to such rock types as granite, volcanic lavas, greywacke, etc.; but it can be said that on volcanic lavas (basalt, dolerite, etc.) Parmelia species are constantly present and in particular P. caperata, P. conspersa, P. perlata, P. cetrata, P. laevigata, P. perforata, P. saxatilis, P. trichotera and several others in section Melanoparmelia. Very common also are Placopsis gelida, P. perrugosa, P. rhodocarpa and P. trachyderma. Volcanic rocks form a congenial substrate for Candelaria vitellina, Dermatocarpon insigne, Diploschistes spp., Rinodina thiomela, Sterocaulon corticatulum and above 1,000 ft. S. gregarium. The writer has no information about high level lichens on the North Island volcanoes. On most rock types Buellia, Lecanora. Lecidea and Pertusaria are well represented.

page 24

5. Epiphytic Lichens

(a) Tree-trunks and Branches in Forest Interior.

A large number of lichens grow on bark, leaves, logs, shrubs and posts, those within the forest being of necessity shade tolerant to some degree. The dominant and largest lichens belong to the family Stictaceae. In different localities the species may differ but wide-spread and very common members of this family are Sticta filix, and S. latifrons, Pseudocyphellaria billardieri, P. carpoloma, P. chloroleuca, P. coronata, P. flavicans, P. fossulata, P. freycinetii, P. impressa and P. psilophylla, and in the wetter areas P. glabra and P. homeophylla.

Common but less conspicuous lichens on the bark of forest trees belong to the following genera — Collema, Coenogonium, Leptogium, Megalospora, Menegazzia, Myxodictyon, Pannaria, Parmeliella, Pertusaria, Phlyctella, Psoroma, Pyrenula, Sagenidium, Sphaerophorus, and Thelotrema. The lichen epiphytes of the subalpine beech forests mostly belong to the same genera with Sticta and Pseudocyphellaria still dominant, the usual species including Sticta filix, S. latifrons, Pseudocyphellaria coronata, P. fossulata, P. hirta, P. subcaperata, and less commonly P. rubella and P. obvoluta. In stations to which sunlight has access species of Parmelia, Ramalina and Usnea may become established.

(b) Forest Canopy.

Branches and twigs are here exposed to stronger light and support a lichen flora differing considerably from that within the forest. Here the dominant genus is Usnea (U. capillacea, U. xanthopoga etc.) often smothering the tree-tops (living and dead) so densely as to be visible at distances of a mile or more. Commonly the pioneers are crustose lichens (Arthonia, Arthothelium, Bacidia, Catillaria, Lecidea, Lopadium) soon to be followed by the larger fruticose or foliose lichens belonging mainly to Hypogymnia, Menegazzia, Pannoparmelia, and Parmelia, or to Usnea and Ramalina. In the wetter areas Sphaerophorus stereocauloides, Pseudocyphellaria coronata, P. hirta, may follow.

(c) Isolated Trees in Open Spaces.

Because exposed to full light, the trees of open hillsides and similar stations also bear lichen epiphytes distinct from those of trees within the forest. Thus Parmelia spp. absent within the forest are perhaps the commonest lichens on trees in the open. Other conspicuous species in lowland stations include both Teloschistes chrysophthalmus on the branches, and Xanthoria parietina on the trunks of smooth-barked trees. The latter is usually var. incavata, a pale yellow variety that forms circular patches to 8 in in diameter. In damp localities species of Hypogymnia, Ramalina, and Usnea are frequent. The most common and conspicuous crustose lichen is Haematomma punicea known by its numerous white bordered pink page 25 apothecia. On smooth barked trees in particular, numerous crustose species of Lecanora, Lecidea, Opegrapha and other script lichens, any Pyrenula, etc. abound. Trees on the forest margin commonly have Parmelia perlata, P. trichotera and various species of Stictaceae less common on fully isolated trees.

(d) Logs, Tree Stumps, Exposed Roots and Posts.

Damp logs on the forest floor afford a congenial substrate for several species both of Leptogium and of Peltigera and occasionally for Pseudocyphellaria hookeri, all almost black in colour and containing a blue-green phycobiont. Sphaerophorus melanocarpus var. australis and S. tener may also occur here.

Logs and tree stumps in open stations in areas of high rainfall as at Cascade Creek on the road to Milford Sound, support a luxuriant lichen flora of a dozen Cladonia spp., Cladia aggregata, Sphaerophorus tener, and Stereocaulon ramulosum. On similar substrates in drier climates red fruited species of Cladonia (C. bacillaris, C. floerkeana, C. macilenta and C. pleurota) are common as are species of Parmelia, absent in the wetter areas. Brown-fruited Cladonias very commonly noted here include C. barbonica, C. cornutoradiata, C. pityrea, and C. verticillata. Wooden fence posts frequently support various species of Hypogymnia, Menegazzia and Parmelia and of Ramalina and Usnea.

(e) Shrubs.

Shrubs on the forest margin, on open hillsides, and in the subalpine belt each support a number of lichen species rare or absent in the other stations, as well as others common to all. Lichens found on the topmost twigs of shrubs on the forest margin are as a rule mainly species either of Parmeliaceae or Usnaceae, with Teloschistes and Haematomma as occasional associates. Usneas of this substrate include P. florida, U. inermis, U. simplex, and U. xanthopoga and less frequently U. contexta. Ramalina geniculata R. dilacerata, R. leiodea, R. menziesii and R. pollinaria are the more usual species on shrubs in the Otago area, associated crustose lichens being species of Lecanora, Candelaria, Haematomma, Pannaria, and more rarely Pyrenula.

Subalpine shrubs have as a rule a more numerous and varied lichen flora in which Parmelia and Pseudocyphellaria are often well represented, but a full catalogue for this substrate has not been compiled. Conspicuous species are Hypogymnia enteromorpha by reason of its largely black colour, and H. inflata because of its swollen, sausage-like thallus. Another distinctive lichen more common on the ground or on the bases of tussock grasses, but also present on shrub bases, is Pertusaria dactylina. In swampy places Usnea capillacea and U. contexta occur both on the ground and on low shrubs.

page 26

6. Earth

(a) Lowland and Montane Soils.

The dominant genus of epigean lichens is Cladonia, all of its seventy species occurring on soil at times, even though many are more usually seen on logs. Barren heath and peat soils commonly have a Cladonia cover of many species, the most frequently seen including C. borbonica, C. capitellata, C. carassensis, C. cariosa, C. cervicornis, C. chlorophaea, C. cornutoradiata, C. crispata, C. deformis, C. degenerans, C. fimbriata, C. gracilis var. chordalis, C. leptoclada, C. pityrea, C. pleurota, C. scabriuscula, C. subdigitata, and C. verticillata. The associated lichens are usually species of Baeomyces, Cladia or Stereocaulon.

(b) Subalpine soils.

Swampy and boggy subalpine soils are commonly inhabited by the three species of Cladia — C. aggregata and C. retipora on raised mounds, and C. sullivanii usually on wetter ground; and in Otago by Cladonia carneola and C. aueri, two species found also near sea level at Awarua and in Stewart Island. Raised mounds in the bog also in many places (e.g. Arthurs Pass) support Cladonia deformis, C. leptoclada, C. pleurota, C. pyxidata and C. subdigitata. The genus Siphula is represented by five or six species of which the commonest and most widespread is S. medioxima. In common with Thamnolia vermicularis the Siphulas are found both on boggy and grassland soils.

In grasslands Hypogymnia lugubris is frequently seen and more rarely H. enteromorpha. In Stewart Island and in Fiordland Sphaerophorus tener is plentiful and on the subalpine soils of Otago mountains Alectoria minuscula, A. nigricans, Cetraria islandica, Cornicularia aculeata and Solorina crocea are to be seen. Many species of Sticta and Pseudocyphellaria normally epiphytic are also to be found on subalpine grassland soils. Such include Sticta filix, Pseudocyphellaria aurata, P. carpoloma. P. crocea, P. delisea, P. durvillei, P. endochrysea, P. flavicans, P. leehleri, P. mougeotiana and also Lobaria laetevirens.