General.

In North Island, the Tararua mountains excepted, N. cliffortioides forest forms the uppermost belt on all mountains where Nothofagus is present, but on the Waimarino Plain (VP.) it descends to less than 900 m. altitude, possibly owing to former forest of a different class having been destroyed during a volcanic eruption¹.- Even in South Island a N. cliffortioides association rarely descends to much below 600 m. altitude, although, as already explained, it is not an uncommon member of many lowland forests. Where there is an abundant rainfall the association is continuous with montane forest, but where tussock-grassland conditions prevail, it is generally confined to gullies, hollows, or the sheltered side of river-terraces. In such cases, there is no merging of forest and tussock-grassland, but the tree-mass ends abruptly.

Dry Nothofagus cliffortioides forest.

This class of forest is distinguished by its paucity of species, the open undergrowth and the few species of bryophytes.

In North Island, the distinct association, described below, occurs on the east of the central volcanoes (VP.) and owes its dry character to the permeable pumice soil rather than to lack of rain. In South Island, dry N. cliffortioides forest occurs at various places on the ranges, extending eastwards from the Divide (especially in NE. and E.). There, too, it is not lack of rain alone which stamps the forest, but the violent winds so frequently hot and dry.

The associations of the Eastern and North-eastern districts are chiefly distinguished by the poverty of undergrowth which, frequently, when the substratum is shallow clay on a steep slope, consists merely of young southern-beeches and seedlings with patches of the mosses Dicranoloma robustum, D. leucomoloides and D. setosum. The trees are slender, about 9 m. high and their branching scanty. In many places, the ground is bare the clay showing through a coating of dead leaves and twigs; where driest the fallen trees are destitute of a mossy covering. Frequently the undergrowth is richer, but large areas may be occupied only by juvenile trees, for N. cliffortioides is short-lived, and, as the adult trees fall, light is let in, seedlings grow vigorously and the forest rapidly regenerates (Fig. 68). Lyco-podium fastigiatum and the summergreen Hypolepis Millefolium are generally abundant.

Or in the dampest places, there will be plenty of Polystichum vestitum, 60 cm. and more tall and sheets of Hymenophyllum multifidum. In some localities Sphagnum cushions are present on which may grow Oxalis lactea. The undergrowth, may consist of Coprosma propinqua, C. parviflora, C. linarii-folia (E.), and Pittosporum divaricatum (E. and NE.). In the Eastern district, Hoheria Lyallii, Griselinia littoralis and various shrubs may grow on the forest's outskirts, but usually the assocation ends abruptly and one steps from the shade of the trees into the open tussock-land.

Wet Nothofagus cliffortioides forest.

In this group of associations the undergrowth is denser than in that just described, more species occur, and there is an actual moss-carpet or small moss-cushions. The forest, too, either makes a continuous covering, extending from the montane to the upper subalpine belt, or, succeeding some other forest-association, forms the uppermost belt of tree-vegetation. All the already-mentioned species may be present and, in addition, others according to the geographical position of the forest.

Wet N. cliffortioides forest occurs in quantity on the Ruahine Mountains, the Waimarino Plain, to the west and south of Ruapehu and most likely on the highest peaks of the East Cape district. In South Island, it is common on the eastern slopes of the Southern Alps within the area reached by the north-western rain. In the Waimakariri Basin (E.) there is a most extensive area, the mountain slopes being covered with a dark mantle of trees from 600 to 1200 m. altitude (Fig. 39), but in a few localities there are small colonies of N. fusca and smaller still of N. Menziesii. In many other parts of South Island, the forest under consideration is confined to the uppermost forest-belt.

On the south of Mount Ruapehu a Nothofagus cliffortioides association occupies about the last 100 m. of the forest-mass with its timber-line at page 259about 1300 m. It contains more or less Libocedrus Bidwillii (sometimes only 5.2 m. high) and the small podocarps, Dacrydium Bidwillii and D. biforme; in places Gleichenia Cunninghamii forms close masses, and prostrate Leucopogon fasciculatus is characteristic. The following, together with those already cited, make up the bulk of the community: — Polystichum vestitum, Blechnum penna marina, Lycopodium fasiigiatum, Podocarpus nivalis, Phyllo-cladus alpinus, Gahnia pauciflora, Astelia Cockaynei, Libertia pulchella, Griselinia littoralis, Myrtus pedunculata, Nothopanax simplex, N. Colensoi, Suttonia divaricata, Coprosmapseudo-cuneata, C. parviflora and C. foetidissima. Hymenophyllum multifidum is abundant.

The Waimarino Plain's association at 900 m. altitude is much as the last but amongst its important members are some which do not reach the final forest-belt, especially: — Cordyline indivisa, Rubus australis, Carpodetus serratus, Pittosporum Colensoi, Hebe salicifolia (one or more jordanon) and Coprosma tenuifolia. On the margin of this association there is tall shrubland (an early stage of forest) containing amongst other species Phormium Colensoi, Cordyline indivisa (Fig. 69), young Nothofagus cliffortioides, Nothopanax Colensoi and Hebe salicifolia.

The extensive forest of the Waimakariri (E.), in its lower part, was fairly uniform. In places, young N. cliff or tioides dominated the undergrowth; in other places, was composed of small Phyllocladus alpinus, Griselinia littoralis and the usual Coprosmae. The floor was carpeted with several species of Dicranoloma, Hymenophyllum villosum and H. multifidum. Polystichum vestitum were abundant. Where small rivers pass through the forest there were various subalpine shrubs on its outskirts, particularly in the case of the tributaries of the River Poulter, the chief being Olearia arborescens, 0. lacunosa, 0. avicenniaefolia, Senecio elaeagnifolius and the tuft-tree, Dracophyllum Traversii. Near the timber-line, the undergrowth was far denser and species of the subalpine-scrub joined the association. Where there have been land-slips there are bright-green colonies of Hoheria glabrata.

On the rocky ground of the Pikikiruna Range (NW.), until quite recently, a remarkable Nothofagus association occurred, but, since my first visiting it in 1915, it has been almost entirely destroyed by fire and replaced by an open association of shrubs, principally species and hybrids of Hebe.

The ground on which this tree-association grew consists of most irregular, much-weathered, honey-combed mounds of hard limestone, full of holes which provide complete drainage and render the habitat, though in a very wet climate, essentially xerophytic.

Nothofagus cliffortioides, about 7.5 m. high was dominant with its slender trunks far apart, so that much light entered the association. In consequence, there was an undergrowth composed of more or less xerophytic (mostly epharmonically) shrubs &e., e. g.: Asplenium Trichomanes (rock crevices), page 260Phyllocladus alpinus, an occasional small Libocedrus Bidwillii, Uncinia caespitosa, Astelia Cockaynei, Pittosporum divaricatum, Pimelea longifolia, P. Gnidia, Metrosideros lucida, Nothopanax simplex (mesophytic), N. anomalum, Corokia Cotoneaster, Suttonia divaricata, Olearia avicenniaefolia, Traversia baccharoides.

General.

This group is distinguished by the dominance of N. Menziesii, but N. fusca, N. cliffortioides and × N. cliffusca may be present, as also Libocedrus Bidwillii, Podocarpus Hallii and Weinmannia racemosa.

In North Island, N. Menziesii forest is common on the Dividing Range and the Volcanic Plateau (includes the central volcanoes) and, in South Island, in the North-western, Fiord, and South Otago districts, and portions of the Eastern and southern part of the Western districts. In certain localities, it forms the highest altitudinal belt, but only where N. cliffortioides is wanting or in small quantity. Here both montane and subalpine forest are dealt with.

All the species found in any montane-subalpine Nothofagus forest are present in some part or other of the community, but more are usually included than in the N. cliffortioides communities.

Generally the dominant trees of N. Menziesii are low, their crowns scanty, their trunks irregular, buttressed (sometimes to an excessive extent), and frequently moss-clad. The undergrowth consists of an upper tier of shrubs and a lower of floor-plants, these, however, not of equal height. In some localities, certain of the shrubs mentioned below rise as small trees above the average level. The following occur throughout: — Dacrydium Bidwillii, Phyllocladus alpinus, Wintera colorata, Aristotelia fruticosa, Nothopanax Colensoi, N. simplex, N. anomalwn, Griselinia littoralis, Cyathodes acerosa, Suttonia divaricata, Coprosma foetidissima, C. Colensoi, C. pseudocuneata and C. parviflora. Various filmy and creeping ferns, Enargea parviflora (creeping amongst moss), Libertia pulchella and species of Uncinia are common floor-plants, but of far greater physiognomic importance are the taller ferns, especially Polystichum vestitum, the silvery masses of Astelia Cockaynei and the tall green tussocks of Gahnia pauciflora (North Island and parts of NW.) or G. procera (South Island).

The upper forest of Mount Te Aroha (Th.).

Montane forest of East Cape district.

At an altitude of about 700 m. on the Huirau Mountains, Nothofagus Menziesii and N. fusca replace the trees of the subtropical rain-forest and Nothofagus forest — possibly with N. cliffortioides dominant in the uppermost belt — ascends to the summits. At 900 m. altitude, owing to the N. Menziesii trees being far apart, the undergrowth was so dense at the place visited that few, if any, seedlings were present on the forest-floor. This undergrowth was about 3 m. high and composed of Dicksonia lanata (the trunkless var.) in great abundance, Leptopteris superba, Astelia nervosa var. sylvestris, Enargea parviflora, Wintera colorata, Ixerba brexioides, Quintinia serrata, Nothopanax Colensoi, N. simplex, Dracophyllum latifolium, Coprosma tenuifolia, C. parviflora, C. foetidissima, Alseuosmia quercifolia and Senecio Kirkii.

Montane-lower subalpine forest of the Volcanic Plateau.

N. Menziesii is taller and with straighter trunks and larger crowns than is general in forest of this class. N. fusca is common, especially at the lower limit of the association. At first, Coprosma tenuifolia is plentiful but it gives place higher up to C. foetidissima. The fern Polypodium novae-zelandiae creeps over fallen trees. Alseuosmia quercifolia is plentiful. The other species are those common to N. Menziesii forest in general. At the lowest level, N. Menziesii is a massive tree with large buttresses; even at 900 m. altitude trees 21 m. high and 90 cm. diam. are not uncommon.

The uppermost belt of the Tararua Mountains.

The forest varies much according to exposure to wind; in the gullies, trees are 10 m. high but, on the ridges, they are much smaller. The trunks of N. Menziesii, slender, fairly straight much mossed, rise out of the undergrowth, the upper branches short and gnarled. On the floor there is much Hymenophyllum multifidum, stunted Blechnum procerum and Astelia Cockaynei. The belt begins at an altitude of about 600 m. and ends at 900 m. as a minimum. At first, there is plenty of N. fusca; Podocarpus Hallii and Weinmannia racemosa are present throughout, the latter often a shrub. Pittosporum rigidum occurs in the uppermost part with other plants of the subalpinescrub, especially Senecio elaeagnifolius. Hybrids in which Coprosma Colensoi, C. Banksii and C. foetidissima all play a part are common.

Upper forest of Mount Stokes (SN.).

Various associations of the North-western district.

From information supplied by F. G. Gibbs the association on Mount Arthur has evidently much in common with the last two, but it differs in the presence of Pseudopanax lineare and in the colonies of Dracophyllum Traversii of its upper portion. At 1020 m. N. Menziesii gives place to N. cliffortioides.

The subalpine forest of Mount Rochfort is a combination of N. Menziesii and N. cliffortioides associations, so far as canopy-trees go, but its contents and habit place it with the former. Metrosideros lucida, Weinmannia racemosa, Quintinia acutifolia, Pseudopanax lineare and, near its lower limit, Metrosideros Parkinsoni¹ are common. On the floor are innumerable mosscushions, of great dimensions which intermingle, and, where a slope descends steeply, form veritable cascades. On the ground, the small shrub Wintera Traversii² is fairly common. Astelia Cockaynei is abundant and the tufttree Dracophyllum latifolium, its trunk more slender than that of D. Traversii is frequently conspicuous.

Governor's Bush near Mount Cook hermitage (east of W. near junction with E.).

In the vicinity of Mount Cook, as is seen more clearly further on, high-mountain species occur at a low level, but this is not particularly in evidence in the small area of Nothofagus Menziesii forest.

N. Menziesii is only a slender, small tree, its trunk 45 cm. diam. at most. There is a fairly rich undergrowth as follows: — Blechnum fluviatile, B. procerum, Polystichum vestitum, Hypolepis Millefolium, Podocarpus nivalis, P. Hallii, Phyllocladus alpinus, Carex Cockayniana, Uncinia uncinata, U. caespitosa, U. leptostachya, juvenile N. Menziesii, Pittosporum tenuifolium, P. divaricatum, Rubus schmidelioides var. coloratus, Aristotelia fruticosa, Hoheria glabrata (where much light), Nothopanax Colensoi, Griselinia littoralis, Coprosma pseudo-cuneata, C. parviflora. C. linariifolia, Lagenophora petiolata and Senecio elaeagnifolius.

Associations of the Fiord and South Otago districts.

The species are those of N. Menziesii forest in general but, on the whole, the conditions on the actual Divide are more favourable for the establishment of subalpine shrubs &c., e. g. Pseudopanax lineare and Archeria Traversii var. australis, and the general bryophyte content of the forest reaches its maximum. As for the undergrowth of the Fiord-South Otago forests it was originally fairly dense the physiognomic species being various divaricating-shrubs, erect bushes of Wintera colorata and Coprosma foetidissima with far-extending, arching, twiggy branches. The upper forest belt of the Longwood Range was (or is?) remarkable for its great bryophyte cushions.

Southern kawaka-totara (Libocedrus Bidwillii-Podocarpus Hallii) group.

In its various forms this is the most important of the subalpine subtropical forests. It is distinguished by the dominance of either of the species cited above, and the Libocedrus, when abundant, with its erect habit and pyramidal head, clearly defines the community even when viewed from afar. In South Island it occurs, but not everywhere, in the subalpine belt of the North-western, Western and Eastern districts and originally to some extent on hills near Dunedin; and, in North Island, on Mount Egmont and the Volcanic Plateau. As will be seen, it is closely related to tree-composite forest, indeed the latter near the source of the Rakaia is a connecting-link between the two groups.

On Mount Hauhungatahi (VP.) there is an association of this class. This mountain is an isolated extinct volcano, 1520 m. high, situated west of Ruapehu. It is forest-clad up to about 1140 m. altitude. At the base of the mountain, and below, at a height of 780 m. or less, the podocarp-forest is replaced by a southern kawaka-totara association. The trees consist of: — Libocedrus Bidwillii (first appearing at about 600 m. alt.), Podocarpus Hallii, P. ferrugineus, Dacrydium cupressinum, D. Colensoi, Weinmannia racemosa and Olea Cunninghamii. The smaller trees and shrubs of the undergrowth are Phyllocladus alpinus, Wintera colorata, Carpodetus serratus, juvenile Elaeocarpus Eookerianus, Aristotelia fruticosa, A. serrata, Melicytus lanceolatus, Myrtus pedunculata, Fuchsia excorticata, Nothopanax simplex, N. Colensoi, N. anomalum, Pseudopanax crassifolium var. unifoliolatum, Schefflera digitata, Griselinia littoralis, Suttonia salicina, S. divaricata, Coprosma grandifolia, C. robusta, C. tenuifolia, C. parviflora, C. Colensoi, C. foetidissima and Alseuosmia quercifolia. Dicksonia lanata (trunkless) ascends to 1080 m., or more, and may form much of the undergrowth, its fronds being 1.5 m. long. Many lowland ferns are common and Leptopteris superba forms considerable colonies. At an altitude of 960 m. (Phillips Turner 1909: 3), Dacrydium cupressinum, hitherto abundant, becomes much scarcer and the forest is more typically subalpine with Libocedrus Bidwillii dominant and Podocarpus Hallii, Dacrydium Colensoi and D. intermedium abundant. Tussocks of Gahnia pauciflora become characteristic and the subalpine-scrub plants of the vicinity enter into the association. In some parts of this association, as where it abuts on the Waimarino Plain, near Horopito and elsewhere, the handsome tuft-tree Cordyline indivisa is plentiful. Close to the timber-line the forest becomes very low (scrub-forest), and it is closely related to bog-forest and subalpine-scrub. Its small trees are Libocedrus, Dacrydium intermedium, D. biforme, Phyllocladus alpinus, Griselinia littoralis and Dracophyllum longifolium.

On Mount Egmont an association containing Libocedrus is apparently confined to the vicinity of the North mountain-house and does not extend page 269to the Stratford house. It commences at about an altitude of 900 m. with Podocarpus Hallii in abundance, but Libocedrus Bidwillii soon becomes dominant, though Podocarpus Hallii, Weinmannia racemosa and Griselinia littoralis are abundant. This latter is bent, arched and gnarled, while its trunk may be covered by sheets of the dark, curled leaves of Hymenophyllum villosum and yellowish-green cushions of Dicranoloma Billardieri. The common shrubs of the association are: — Wintera colorata, Carpodetus serratus, Aristotelia, serrata, Melicytus lanceolatus, Fuchsia excorticata, Nothopanax Sinclairii, N. Colensoi, Suttonia divaricata, Hebe salicifolia (form with narrow leaves), Coprosma grandifolia, C. tenuifolia (abundant), C. parviflora, C. egmontiana and Senecio elaeagnifolius var. Buchanani. The sole liane is an occasional plant of Rubus australis. Seedlings and young trees are constantly epiphytic, e. g. Coprosma lucida var. angustifolia, Griselinia littoralis, Nothopanax Colensoi and N. Sinclairii, the last two frequently killing and replacing their host. A striking feature is the profusion of bryophytes, especially Hepaticae, both on the floor and tree-trunks; the undergrowth is particularly dense and Wintera colorata plays a most important part; on the floor is an epharmone of Astelia nervosa var. sylvestris.

On the west of the Southern Alps, and extending for 160 km. or more southwards from the R. Taramakau, the southern kawaka-totara belt commences at an altitude of about 600 m., Podocarpus Hallii being the first tree to arrive. From North Island associations this differs only in certain floristic details. Weinmannia racemosa and Metrosideros lucida are abundant at first. Tussocks of Gahnia procera are a feature of the floor-vegetation. Lianes and tree-ferns are absent. At the upper limit subalpine shrubs by degrees enter in until a distinct belt of forest results.

The highest peaks of Banks Peninsula doubtless originally carried a belt of southern kawaka-totara forest, for there are ample remains, while a small piece in its virgin state still exists on Mount Sinclair. Weinmannia racemosa, Metrosideros lucida and other species are absent, but Cordyline indivisa, plentiful in Westland, but not occurring elsewhere east of the Divide, is fairly common. Other members of the association are Wintera colorata, Griselinia littoralis, Fuchsia excorticata and Nothopanax arboreum.

Kamahi (Weinmannia racemosa) group of associations.

Weinmannia racemosa is frequently dominant in parts of southern kawaka-totara forest, while, in certain localities, it forms an almost pure association — so far as tall trees are concerned.

On Mount Egmont kamahi forest is so striking that it has received the popular and expressive name of "Goblin forest". It occurs as a distinct belt from the neighbourhood of Dawson Falls to the North Egmont house and it probably extends right round the mountain.

At first, there are some comparatively low trees of Dacrydium cupressinum page 270but these soon give out and those of Weinmannia decrease in stature and become much-branched, the branches at first more or less erect, but with increase of altitude they extend far horizontally and are gnarled and irregular in shape. Both trunks and branches are covered densely with mosses, liverworts and filmy-ferns (Hymenophyllum multifidum, H. villosum, H. flabellatum) which could not be in such profusion but for frequent rain. Griselinia littoralis is an important small tree and Fuchsia excorticata occurs here and there. The undergrowth consists of ferns and rather freely-branched shrubs, the following being common: — Blechnum procerum, B. fluviatile, Polystichum vestitum, Uncinia Banksii, Astelia nervosa (unnamed jordanon), Wintera colorata, Carpodetus serratus, Coprosma parviflora, C. tenuifolia. At a higher altitude Podocarpus Hallii enters the association which then becomes equivalent to that in which Libocedrus is present. At about 1200 m. altitude, the forest gives place to subalpine-scrub

On Mount Hauhungatahi, in places, there is a Weinmannia association more or less of the "Goblin Forest" character.

Southern-rata (Metrosideros locida) group of associations.

Forest of this class is wide-spread in the Western district, it is montane rather than subalpine, but as mountain plants descend so low in that locality, it is here included with subalpine forest.

At above 450 m. altitude in the Western district M. lucida becomes dominant and the lowland podocarps gradually decrease in numbers. Weinmannia racemosa in places is so plentiful as to dominate. Quintinia acutifolia is conspicuous through its somewhat fastigiate habit as a sapling and the yellowish leaves blotched with purple but pale beneath. Many of the lowland shrubs and ferns are present. The undergrowth is dense, especially in gullies. Bryophytes (species of Gottschea, Schistochila, Aneura, Mniodendron, Plagiochila, Lembophyllum &c.) and Hymenophyllaceae abound. Leptopteris superba forms extensive colonies.

At the Franz Josef glacier, the terminal face of which descends to 213 m., the southern-rata association comes on to the ice-worn rocks at a few metres from the ice on either side of the glacier. The forest here, the roof of which has the characteristic billowy appearance, consists principally of the following: Metrosideros lucida and Weinmannia racemosa (the dominant canopy-trees), Carpodetus serratus, Coriaria arborea, Aristotelia serrata, Hoheria glabrata, Melicytus ramiflorus, Pseudopanax crassifolium var. unifoliolatum, Schefflera digitata, Griselinia littoralis, Hebe salicifolia, Coprosma lucida, Olearia arborescens and O. avicenniaefolia. The pterido-phytes include Hemitelia Smithii (tree-fern, but here of low stature), several Hymenophyllaceae, Hypolepis tenuifolia, Histiopteris incisa, Blechnum procerum, B. lanceolatum, Asplenium bulbiferum, A. flaccidum, Polystichum vestitum, Polypodium diversifolium, P. Billardieri and Lycopodium volubile.

At Mount Peel (E.) there is a small southern-rata association with page 271M. lucida as the sole tree "on rocky knolls and. slopes with a westerly-aspect (H. H. Allan, 1926: 44) which is a succession after Leptospermum ericoides"¹. On the floor there may be much Blechnum procerum and Alsophila Colensoi and near streams colonies of Gleichenia Cunninghamii.

In Stewart Island at an altitude of 300 m. the forest decreases in height, Metrosideros lucida, sometimes with prostrate trunks, becomes more abundant, especially on exposed ridges, Weinmannia is still plentiful, tall Leptospermum may appear, and moss-cushions become far commoner. On the lower hills, so far as is known, at about 270 m., the forest gradually decreases in height until its interior is a tangle of stems from semi-prostrate, slender trunks. On the uneven floor great cushions of Plagiochila gigantea and Dicranoloma robusta abound (Fig. 72).

General.

This is distinguished by the dominance, or occasionally sub-dominance only, of shrubby or stunted arboreal species of Olearia and Senecio, one or both. Various divaricating-shrubs (spp. of Coprosma, Aristotelia fruticosa, Pittosporum divaricatum, Suttonia divaricata) will be present. Also one or other of the fastigiate species of Dracophyllum, phormium Colensoi, Cassinia Vauvilliersii, Phyllocladus alpinus, Nothopanax Colensoi and one or two species of Hebe are frequent members and Dracophyllum, Phyllocladus, Cassinia or even Hebe may in places dominate.

The trunks of the tree-composites are generally prostrate and yet treelike, their horizontal spread exceeding the height of the association. The divaricating-shrub greatly increase the general density. The roof will be fairly level but pierced here and there by Dracophyllum (Fig. 73).

Shrub-composite scrub requires a high rainfall for its full development. In North Island, it occurs on Mt. Hikurangi, the Ruahine and Tararua Mts. and Mt. Egmont. In South Island, it is a characteristic feature of the Western district on both sides of the Divide, making, in many places, a broad belt above the forest and partly filling the cirques at the sources of glacial rivers. Similar scrub occurs in the Fiord district; it is also highly developed in Stewart Island. In what follows an attempt is made to give some idea of its chief floristic characteristics in different localities.

Mount Hikurangi (EC).

The scrub occurs (from information generously supplied by W. R. B. Oliver who recently ascended this mountain on "cliffs and steep rocky slopes, especially on the northern face of the mountain". Senecio Bidwillii (50 cm. high) and Podocarpus nivalis are dominant and mixed with them are Dracophyllum recurvum, Pimelea buxifolia and Hebe tetragona. Tussocks of Danthonia Raoulii var. flavescens and Aciphylla conspicua (if this can be so termed) are common. Coprosma pseudo-cuneata and Olearia Colensoi are present. Beneath the scrub are Hymenophyllum multifidum, Lycopodium fastigiatum, L. australianum and Schizeilema Allanii.

Mount Egmont (EW.)

The scrub commences at about 1140 m. and gives out at about 1240 in. Senecio elaegnifolius var. Buchanani is generally dominant, but sometimes Dracophyllum filifolium rules. The other principal species are Podocarpus Hallii, Carmichaelia australis var. egmontiana, Nothopanax Colensoi, N. Sinclairii, Griselinia littoralis, Suttonia divaricata, Hebe salicifolia (resembling var. paludosa but probably distinct), Coprosma tenuifolia, C, egmontiana, C. parviflora, Olearia arborescens and Cassinia Vauvilliersii,

Tararua Mountains (RC.).

Olearia Colensoi is frequently dominant, but O. arborescens and Senecio elaeagnifolius are often abundant. Other page 278shrubby species are: Pittosporum rigidum, Nothopanax Colensoi, N. Sinclairii N. anomalum, Dracophyllum longifolium, D. filifolium, Suttonia divaricata, Hebe salicifolia var., Coprosma pseudo-cuneata, C. foetidissima, 0. lacunosa, 0. arborescens X lacunosa and Senecio Bidwillii.

Southern Alps and mountains of North-western district.

Olearia ilicifolia or 0. Colensoi are frequently dominant; 0. arborescens and its many hybrids with 0. ilicifolia, 0. nummularifolla, 0. avicenniaefolia, Senecio Bidwillii, var. viridis and S. elaeagnifolius are common shrub-composites¹. The following occur throughout and are often important constituents: — Phyllocladus alpinus, Dacrydium biforme, D. Bidwillii, Podocarpus Hallii, P. nivalis Phormium Colensoi, Pittosporum divaricatum, Carmichaelia grandifiora, Arts-totelia fruticosa, Hoheria glabrata, Nothopanax Colensoi, N. simplex, Pseudopanax lineare, Griselinia littoralis, Gaultheria rupestris, Dracophyllum longifolium, D. Lessonianum², Archeria Traversii, Hebe salicifolia, Hebe subalpina, Coprosma serrulata, C. pseudo-cuneata, C. parviflora, C. ciliata. C. foetidissima and C. ramulosa.

In the South Otago and Fiord districts, scrub dominated by Olearia moschata is not uncommon. Thus, in the Lake Harris hanging valley the combination is 0. moschata (dominant), Aristotelia fruticosa, Hebe Cockayniana (abundant), H. buxifolia, Coprosma ciliata and Senecio revolutus. A somewhat similar scrub occurs on the Takitimu Mountains.

On Tooth Peaks, at about 900 m. altitude, the dominant shrubby composite is Senecio cassinioides and it is accompanied by extensive colonies of Aciphylla maxima of the surprising height of 4.5 m. (Fig. 57), together with Aristotelia fruticosa, Coprosma rugosa, C. parviflora and C. rhamnoides, and as undergrowth, Hypolepis Millefolium, Poa Cockayniana and Acaena Sanguisorbae var. sericeinitens. On Rough Peaks (SO.), according to G. Simpson and J. S. Thomson (1926:373) the combination in an allied association is Senecio cassinioides, Podocarpus nivalis and Phyllocladus alpinus.

Stewart Island.

North-eastern district

. Shrub-composite scrub made up of one species only (Senecio Monroi) occurs on the Inland Kaikoura Mountains and adjacent parts of the district. The substratum is coarse shingle-slip. Elsewhere the species is a rock-plant, and in this case the stony ground, as it slowly grows, is peopled by plants from the mother-rock.

Phyllocladus scrub.

Phyllocladus alpinus is dominant. The scrub has frequently almost the same composition as the adjacent shrub-composite scrub but dominance of the podocarp lends a distinct facies and colour. The low Phyllocladus forest of the Volcanic Plateau already described when of low stature is a scrub, as in certain gullies on Mount Tongariro and the Kaimanawa Mountains. Its other species are: Dracophyllum montanum (dominant in places), Nothopanax Colensoi, N. simplex, N. Sinclairii, Griselinia littoralis, Leptospermum scoparium, Coprosma pseudo-cuneata, C. parviflora, C. foetidissima and Olearia nummularifolia. In South Island Phyllocladus scrub is common in the eastern part of the Western district.

The Phyllocladus forest of the Sealey Range (W.), already described, gradually becomes stunted into scrub with P. alpinus dominant and the other members of the forest-association present; in its upper part Danthonia Cunninghamii comes in, and in places Hebe macrantha is common. At an altitude of about 1100 m. facing west, the scrub on the Mount Earnslaw Spur (F.) consists of large bushes of P. alpinus of great breadth, accompanied by more or less prostrate Senecio cassinioides, Podocarpus nivalis, erect Hebe buxifolia, Coprosma ciliata and Aciphylla Colensoi.

Cupressoid-podocarp scrub

. Scrub of this type has usually Dacrydium Bidwillii or D. biforme dominant. Apparently, it is commonest on boggy, windswept or "poor" stony soil.

Near Mount Cook Hermitage on old moraine, there is a scrub of this character with yellowish-green D. Bidwillii dominant, forming bushes ± 1 m. high and 2.5 m. through and with the following more or less common: Polystichum vestitum, Phyllocladus alpinus, Podocarpus nivalis, Discaria toumatou, Aristotelia fruticosa, Hoheria glabrata, Hymenanthera alpina, Coprosma propinqua, C. parviflora, C. rugosa and Senecio cassinioides.

On boggy ground occupying roches moutonees or truncated spurs in the east of the Western district, open or dense scrub is common with either species of Dacrydium dominant.

Cupressoid-podocarp scrub also occurs at the timber-line. For example, Mount Greenland (915 m.), an isolated mountain in the north of the Western district contains near its summit a very distinct form of podocarp-scrub (Fig. 74) which though extremely dense is erect, but on the flat mountain page 280summit becomes low and open. The following is its composition:—Dacrydium biforme (dominant), Phyllocladus alpinus, tussocks of Gahnia procera, Pittosporum divaricatum, Quintinia acutifolia, Weinmannia racemosa, Elaeocarpus Hookerianus, Nothopanax Colensoi var. montanum, Pseudo-panax lineare, Leptospermum scoparium, Metrosideros lucida, Dracophyllum Traversii, D. longifolium, Coprosma pseudocuneata, Olearia lacunosa, O. avicenniaefolia, O. Colensoi and Senecio elaeagnifolius. Besides its erect habit a distinct feature of this community is the mixture of forest and scrub species.

Dracophyllum scrub.

On dry South Island mountains, Dracophyllum uniflorum forms on stony ground a more or less pure rather open scrub of a brownish colour. It burns readily and so is less in evidence than it was in the primitive vegetation. Hebe Traversii, species of Cassinia, Olearia cymbifolia, Podocarpus nivalis and Helichrysum microphyllum (NE. only) may be associated plants. Such scrub, becoming more and more open, merges into fell-field.

D. Lessonianum or stunted D. longifolium are frequently dominant in what otherwise would be classed as shrub-composite scrub but the physiognomy is completely changed. But the change is still greather when D. Traversii, a tuft-tree, projects out of subalpine-scrub.

D. Menziesii, of similar life-form to the last named — but in miniature — occasionally dominates in scrubs of the Fiord district. G. Simpson and J. S. Thomson have supplied the following particulars concerning a piece of scrub just above the timber-line on one of the mountains bounding the North Routeburn Vallay (F.). D. Menziesii is dominant; the other species are Podocarpus nivalis, Gaultheria rupestris, D. Lessonianum, Hebe subalpina, H. buxifolia, H. Cockayniana, Olearia moschata, Cassinia Vauvilliersii and Senecio revolutus. The remarkable feature is the presence of Celmisia Walkeri — usually a mat-plant — as a liane scrambling through the shrubs, its stems exceeding 1 m. in length. In Stewart Island, too, D. Menziesii becomes most conspicuous when projecting out of low dense Olearia Colensoi scrub (Fig. 73).

Manuka (Leptospermum) scrub.

This is chiefly a community of the lower subalpine or montane belts and differs but little from the allied lowland association. In Stewart Island, however, thanks to its tolerance of excessive wind through its epharmonic plasticity, it forms a belt at about 450 m. altitude, or even lower (Fig. 75). At first it is mixed with certain forest-shrubs, but it eventually becomes pure, much reduced in size and with bare stems and small head of twisted branches. Beneath are moss-cushions, carpets of Lycopodium ramulosum, tussocks of Gahnia procera, low-growing Cyathodes acerosa and prostrate Dacrydium Bidwillii.

There is closely-related Leptospermum scrub on Mount Greenland and probably other mountains in the Western district.

Cassinia scrub.

It has been shown, earlier on, that for the lowland-montane belt ericoid-scrub of this kind was almost all, if not all, indigenous-induced. On the contrary, there appear to be high-mountain communities of a primitive nature. For example, on Flagstaff Hill (SO.) there is a Cassinia scrub above the timber-line with Alsophila Colensoi as an unexpected member. G. Simpson and J. S. Thomson (1926:373) describe a scrub at 900 m. at the foot of Rough Peaks (SO.) with Cassinia Vauvilliersii dominant, accompanied by Dracophyllum uniflorum, Aciphylla maxima and Gaultheria rupestris, and in open spaces amongst rocks various characteristic high-mountain shrubs, including Olearia moschata and Senecio cassinioides. However, dominance of Cassinia generally means there has been burning and the association it governs must always be looked upon with suspicion.

Southern-beech (Nothofagus) scrub.

The two subalpine species of Nothofagus respond more readily to scrub-conditions than do the trees of other forest-associations, and, in consequence, more than hold their own in competition with subalpine shrubs proper, so that both N. Menziesii and N. cliffortioides forests are frequently succeeded throughout New Zealand by a scrub in which one or other dominates. Such an association may consist almost altogether of Nothofagus cliffortioides, as on many of the drier mountains of the North-western district. Generally where there is an abundant precipitation many of the ordinary subalpine-scrub species accompany the southern-beeches¹.

North Island communities.

On the central volcanoes there are no obligate rock-plants. The vegetation is scanty and besides mosses and lichens consists only of deep-rooting desert or steppe xerophytes, especially, Danthonia setifolia, Poa Colensoi, Anisotome aromatica, Gaultheria rupestris and Helichrysum alpinum¹.

On Mount Egmont most of the fell-field and tussock-grassland species occur on rock, but, in addition to the species of the last paragraph, the following need citing: Coprosma repens, Pentachondra pumila, Drapetes Dieffenbachii, Forstera Bidwillii and Celmisia glandulosa var. latifolia.

The Tararua Mountains, though subject to much rain, mist and cloudy skies, possess an extreme xerophyte in Raoulia rubra¹, a typical vegetable-sheep, its cushions green however, and about 30 cm. diam. The other rock species are fell-field plants, e. g. Anisotome aromatica, A. dissecta, Pentachondra pumila, yellowish-green cushions of Phyllachne Colensoi, Helichrysum alpinum and Leucogenes Leontopodium. Where rocks are near subalpine-scrub, certain shrubs are present, notably Senecio Bidwillii (leaves very thick).

South Island dry mountains communities.

In the North-eastern and Eastern districts, in their upper montane and subalpine belts, the Colobanthus acicularis association occurs with that species dominant. This species is a small, pale-green cushion-plant, made up of very narrow leaves, ± 12 mm. long with long acicular points. The accompanying plants mostly come from the neighbouring tussock-grassland and are: Dichelachne crinita, Danthonia setifolia, Poa caespitosa, Festuca novae-zelandiae, Agropyron scubrun, Phormium Colensoi, Muehlenbeckia axillaris, Stellaria gracilenta, Scleranthus biflorus, Tillaea Sieberiana (semi-obligate rock-plant), Carmichaelia subulata, Discaria toumatou, Hymenanthera alpina, Leptospermum scoparium, Aciphylla Colensoi, Angelica montana, Cyathodes acerosa, Suttonia nummularia, Wahlenbergia albomarginata, Helichrysum bellidioides, Raoulia australis and Senecio bellidioides.

The Pachystegia insignis association, already described for the lowlands, ascends to upwards of 900 m. with Senecio Monroi as a member which — Pachystegia absent — dominates dry rock-faces up to 1500 m. or more altitude (NE.).

In the North-eastern district, in the upper subalpine and alpine belts, a strongly xerophytic station is provided by stacks of much-weathered greywacke standing out from vast shingle-slips (screes). A black fruticose lichen may dominate. Pressed as closely to the rock as possible will be numerous, hard, circular greyish cushions of Raoulia bryoides, the largest some 30 cm. diam. and 17 cm. deep. But the most striking plant, to which the name of the association must be given, is Helichrysum coralloides¹; many of the following will be present: — Helichrysum Selago and H. microphyllum (closely related to H. coralloides), hybrids between the last-named and H. selago — but the 3 species rarely present at the same time, Hymenanthera alpina, forming rigid, open cushions of divaricating stem, Hebe decumbens or H. pinguifolia issuing from crevices, Pimelea Traversii, Colobanthus acicularis, perhaps the beautiful white-flowered Myosotis saxatilis, hard rosettes of Epilobium crassum and probably flattened sheets of Podocarpus nivalis. H. coralloides is confined to the North-eastern district, but dry alpine rocks in many parts of the Eastern and North Otago districts bear a closely-allied association².

Communities of South Island wet mountains.

In the lower subalpine belt the rocks are altogether in the forest-areas, and when in the open occur only on river-beds or the sides of gorges. In such places, various forest-trees and subalpine shrubs are common jutting out from the rocks. In the wettest districts extremely steep cliffs may be actually covered with a close scrub, the rock having become faced with a thick sheet of soil held in position by a network of matted roots. A times, the whole of such a covering slips away for many metres leaving the steep rock-face bare and dripping. Rock of such gorges in the Western district at an early stage may be merely dotted here and there with various herbs and semi-woody plants, e. g, Veronica linifolia (the characteristic true rock-plant), Deyeuxia pilosa, Poa novae-zelandiae, Schoenus pauciflorus, Angelica montana, Epilobium glabellum, Veronica Lyallii, Craspedia uniflora (one or other of the jordanons), and Senecio Lyallii; extensive colonies of Phormium Colensoi are characteristic.

In the upper Clinton Valley, on the smooth face of the precipice where water constantly trickles, there is a curious association consisting of a close growth of a species of Hepaticae which is hidden by a prostrate grass, its culms pressed closely to the liverwort, pointing downwards and forming an open flat continuous mat. Numerous plants of Celmisia verbascifolia grow through the grass their leaves no longer erect but hanging downwards (Fig. 78). Drier cliff is occupied by a combination of Blechnum procerum, Phormium Colensoi and Coriaria angustissima, to be replaced as more soil accumulates, or where the cliff is less steep, by a shrub-association of Hoheria glabrata, Aristotelia serrata, Fuchsia excorticata and Hebe saliciflora var. communis.

The rocks of old moraine rising out of a subalpine herb-field, or steep buttresses, usually ice-worn, or the irregular, rocky walls of a gully rapidly become covered with peat — where such can rest or cling — made from bryophytes, lichens and early spermophyte settlers. Such stations are colonized by many species from the adjacent herb communities, as well as by a few obligate or semi-obligate rock species and others common on rocks. These include great mats of Hymenophyllum multifidum (epharmonic, curled-leaf form), Microlaena Colensoi, the prostrate Dracophyllum Kitkii page 287(NW., W.), Anisotome pilifera, Aciphylla similis, Celmisia Walkeri, and Leucogenes grandiceps; the shrubs Gaultheria fupestris, Coprosma serrulata and Senecio Bidwillii are common¹).

The alpine rocks, if steep, have a sparse vegetation which will include some of the following (the extreme altitudes are mostly from A. Wall, (1925: 19, 20): —Hymenophyllum multifidum, Polypodium pumilum, Microlaena Colensoi, Agrostis subulata, Poa novae-zelandiae (2100 to 2400 m.), Carex pyrenaica, C. acicularis (2400 m.), Marsippospermum gracile (2100 m.), Luzula pumila (2400 m.), Colobanthus acicularis (2400 m.), Hectorella eaesfitosa (2100 m.), Ranunculus Buchanani (SO., F., 2100 m.), R. Grahami (W. in Mount Cook area, 2700 m. and more), Nasturtum Enysii (2400 m.), N. Wallii (SO.), N. fastigiatum, N. latesiliquum (NW.), Cardamine depressa, Pachycladon novae-zelandiae, (SO., F. — 2100 m), Hymenanthera alpina (2100 m.), Epilohium rubromarginatum (NW., W., 2400 m.), Schizeilema Haastii (2100 m.), S. exiguum (NO., SO., F.), Aciphylla Hectori (NO., F., SO.), A. Spedenii (SO., 1800 m.), A. Dobsoni (NO., SO — 2100 m.), A. simplex (SO., 1800 m.), Angelica montana, Anisotome imbricata (SO., F.), Gentiana sp., divisa, (W., Mount Cook area, 2400 m.), Myosotis suavis (east of W., 2100 m.), M. macrantha, M. pulvinaris (SO.), M. concinna (NW.), Hebe ciliolata (2100 m.), H. epacridea (2100 m.), H. Haastii (over 2700 m.), Celmisia brevifolia (SO.), C. Hectori (SO., F., W. 1800 m., C. ramulosa (SO. F.), Raoulia eximia (2100 m.), R. Buchanani (SO., F.), R. Youngii (W., SO.), R. subulata, Leucogenes grandiceps and Cotula pyrethrifolia.

Stewart Island rocks.

Almost any of the subalpine plants may be found on rocks. This is not because they are specially adapted for such a station, but because peat is readily formed in the mountain climate on flat rock surfaces or in crevices, and because the frequent rain never allows the rocks to become too dry for bog xerophytes. The following are the only special rock-plants: Polypodium pumilum, Anisotome flabellata, Raoulia Goyeni and Helichrysum grandiceps.

α. General.

The species fall into two classes — obligate (25 species) and facultative (8 species) — and taking both classes together the 33 species belong to 14 families and 19 genera. The following list includes all the species: — obligate) Poa sclerophylla, Stellaria Roughii, Ranunculus Haastii, R. chordorhizus, R. pauciflorus, R. crithmifolius, Notothlaspi rosulatum, Swainsona novae-zelandiae, Epilobium pycnostachyum, Anisotome carnosula, A. diversifolia, Convolvulus fracto-saxosa, Myosotis Colensoi = (M. decora), M. Traversii, M. angustata — perhaps, M. Cockayniana, Hebe macrocalyx, Veronica Cheesemanii, Lobelia Roughii, Wahlenbergia cartilaginea, Haastia Sinclairii, H. recurva and var. Wallii, Raoulia cinerea, Craspedia alpina — forms in fell-field may be identical —, Cotula atrata and var. Dendyi and the hybrids between them, (facultative), Claytonia australasica, Notothaspi australe, Acaena glabra — almost obligate, Anisotome filifolia, Hebe lycopodioides, H. tetrasticha, H. epacridea and Haastia pulvinaris.

The station, as will be seen from what follows, is strongly hostile to plant-life and but few species are so constructed as to be able to gain a footing, or, if such should happen, to thrive and produce offspring.

The much-jointed greywacke and allied rocks, which comprise the greater part of New Zealand mountains, become so rapidly disintegrated that stone-fragments accumulate to such an extent as to cover the slopes for hundreds of metres. Here and there jagged masses of much corroded rock jut out from these stone-fields but hardly break the monotone of the vast, grey even slopes which extend from the lower subalpine-belt to the mountain-tops. Gullies, often with rocky walls seam the mountain sides, their floors occupied by a stream, its source the base of some great stone-field where all on a sudden water bursts forth.

The stones themselves differ in size but the bulk are generally small, perhaps 5 or 6 cm. long by 2 cm. broad, though some may be much larger. Those of the upper layer are quite loose and, as the surface is steep, they are liable to slide downwards, considerable breadths, when disturbed, moving en masse. At 30 cm. or more below the surface, the ground is more stable and there is generally a good deal of finer debris, sand, and even clay mixed with the coarser stones. Although quite dry on the surface, at a few centimetres depth the substratum is damp, and deeper still ample water, but icy-cold, is available for plants. The climatic features of the habitat depend upon extreme exposure to wind; strong radiation of heat from the stones; powerful heating of the stones themselves and, at times, very bright light. Within the space of a few hours the plants are frequently subjected page 289to burning heat and considerable frost, or one hour they may be surrounded by moist air and the next be exposed to a strong, dry wind. Those which are evergreen bear a heavy weight of snow for four months at a time or more. Nor are occasional droughts unknown. It is obvious then that the ecological conditions of shingle-slip are distinctly those of desert, while in addition there is marked instability of surface. This latter character has, in part, led to the occupation of the ground not merely by certain peculiar life-forms but by 25 distinct species which do not occur in any other formation.

Near the edges of the shingle-slip, the stones are far less liable to move, and there is stability - sufficient for species other than those adapted to the moving debris to settle down, so that, by degrees, the formation is transformed into fell-field. But towards such change the actual shingle-slip association contributes nothing, its members are too far apart and too few to supply appreciable humus to the soil. The formation is indeed distinct in itself and not a phase in the development of fell-field but a definite vegetation-entity the origin of which is wrapped in obscurity.

Shingle-slip, in its unstable and typical form, is confined to those mountains of South Island with a tussock-grassland-climate and is most strongly in evidence in the North-eastern and Eastern districts. Where there is abundant rain the conditions for accumulation of debris are unfavourable, while its occupation by non-shingle plants is much more easy. Certain scoria-slopes of North Island volcanoes are ecologically similar to true shingle-slip.

Taking both the obligate and facultative species together their life-forms are as follows: — herbs 21 (summergreen 14, evergreen 7), semiwoody plants 4, grass-form 1, shrubs 5, biennials 2. Most of the obligate species have important features in common and several of distinct affinities closely resemble one another. Thus, 17 are much the same colour as the stones; all have thick, fleshy or coriaceous leaves and in 24 species they are in rosettes; underground stems more or less strongly developed occur in 17 species, while in 16 the portion of the plant above the ground is annual; with but 2 exceptions, the shoots lie close to the stones and, although this leads to their being buried, the stems have the faculty of growing upwards, while the leaf-texture in many is such as not to be readily damaged by rolling stones. The roots generally extend, in part, horizontally and then descend more ore less deeply. Twenty one species are glabrous, but, on the other hand, the species of Haastia and Craspedia alpina are woolly, the latter being very noticeable through its long, snow-white wool.

β. The associations of true shingle-slip and their allies.

River-bed vegetation.

This has been described at some length for the lowland and montane belts and the definition given for its class of vegetation applies here also. The physiographical and ecological conditions as there indicated match closely those of subalpine river-bed, as far as the larger rivers are concerned, except just at their glacier sources. Even the species are much the same, as is the procession of events in plant-colonization. Such differences, as there are, arise from climate and the colder water of the substratum, while certain species, according to locality, are present which do not descend to or are rare in the lowland belt. Lowland river-bed of the Western and Fiord districts however approximates closely to that of the mountains.

The South Island species, omitting those of fell-field or herb-field which occur in the upper torrent beds, number about 72 and belong to 23 families and 38 genera. Their life-forms are as follows: — grass-form 11 species, herbs 32, semi-woody plants 18 and shrubs 11. At most 10 species belong to the high-mountain flora but nearly all of these descend to the lower montane belt. As in the lowlands the most important members of the formation are the species of Epilobium and Raoulia¹ with E. melanocaulon characteristic of the dry areas and E. glabellum of the wet. Other common species are the grey, low shrub Helichrysum depressum looking half-dead with grey rigid stems and scanty small appressed leaves; great circular mats of Muehlenbeckia axillaris; several species of Acaena; Veronica Lyallii in the wet and V. Bidwillii in the dry areas or stations; Helichrysum bellidioides, Coriaria lurida; C. angustissima (where abundant rain) and the vast polymorphic hybrid swarm between them in which C. sarmentosa also plays a part, Veronica catarractae (F.), Angelica montana, Discaria toumatou and Raoulia glabra. Raoulia Haastii, which forms large green cushions, is the characteristic plant of many river-beds in the Eastern and Western districts and occasionally occurs in the South Otago district.

Subalpine torrent beds of the wet mountains, especially near their sources, contain more or less of the fell-field and herb-field species and their open plant-covering may resemble that of the adjacent fell-fields. So, too, the old bed of the wider valleys often has a considerable florula and the association may be closed, but it is generally rather tussock-grassland dotted with shrubs than fell-field. Hebe buxifolia var. odora and Carmichaelia grandiflora are common on old river-bed on the wet eastern side of the Divide (W.), Coprosma brunnea, its wiry stems hugging the stones, is characteristic, and soft cushions of Myosotis uniflora occur occasionally.

Vegetation of fans.

The vegetation is that of river-bed and commences with the usual species of Epilobium and Raoulia. Finally tussock-grassland or Discaria scrub may be established but the indermediate stage may possess many circular mats of Muehlenbeckia axillaris and extensive colonies of the ferns Blechnum penna marina and Hypolepis Millefolium.

The association occurs principally in the drier areas and the fans — sometimes of great size — are built up by the stony debris deposited at the mouths of gullies or gorges by their streams as they open out on to the valleys, river-beds or plains. Their vegetation depends upon the supply of stones brought down by the torrent and this again is correlated with the age of the gully and the plant-covering of its walls. Fans may be either active or passive, and every transition between the two can be seen. The stony surface is much steeper than that of river-bed in general. There are water-channels but these are usually dry except during heavy rain, the actual stream running underground. Many of the stones are large and much of the debris coarse and piled up into comparatively high but quite unstable terraces liable during flood to damage or absolute destruction.

Closely related to fan vegetation, on the one hand, and to Hebe scrub, on the other, especially in the Eastern district, is an open association with Hymenanthera alpina dominant and, growing between the stones, Hypolepis Millefolium and Blechnum penna marina. The other members of the community are frequently Geranium microphyllum, species of Acaena and their many hybrids, Myosotis australis (yellow flowers, probably not identical with the Australian species), and various shrubs, especially Discaria. The substratum consists of large, lichen-covered stones either at the foot of river-terrace or at the base of mountain slopes, particularly in the montane and lower subalpine belts. Cystopteris novae-zelandiae is common beneath the shrubs.

α. General.

The fell-field formation consists of a group of associations of an extremely open character made up, for the most part, of low-growing xerophytes or subxerophytes and with tussock-grasses present only to a quite limited extent.

The number of species, including a few of the commoner hybrid swarms, is 282 which belong to 40 families and 96 genera, of which the most important are: — (families) Compositae 62, Gramineae 34, Scrophulariaceae 30, Umbelliferae 17, Ranunculaceae 12; (genera) Celmisia 26, Hebe 16, Ranunculus 12, Acaena and Coprosma 7 each.

The following are common species of wide range:— Blechnum penna marina, Lycopodium scariosum, L. fastigiatum, Podocarpus nivalis, Deyeuxia avenoides, Danthonia Raoulii var. flavescens (in a wide sense) and var. rubra, D. setifolia, Poa Colensoi, P. Lindsayi, Festuca novae-zelandiae, Uncinia compacta, Marsippospermum gracile, Astelia Cockaynei, Exocarpus Bidwillii, Muehlenbeckia axillaris, Claytonia australasica, Stellaria gracilenta, Colobanthus crassifolius, Geum parviflorum, G. leiospermum, Acaena Sanguisorbae var. pilosa, Acaena microphylla, A. inermis and hybrids between the three species, Carmichaelia Monroi (in a wide sense), Geranium sessiliflorum var. glabrum, Coriaria lurida, C. sarmentosa, × C. sarlurida, Discaria toumatou, Viola Cunninghamii, Hymenanthera alpina, Pimelea prostrata, P. pseudo-Lyallii, Drapetes Dieffenbachii, Leptospermum scoparium, Epilobium tas-page 295manicum (in a very wide sense), E. Hectori, E. chloraefolium var. verum, E. peduncular e (in a wide sense), E. glabellum, E. novae-zelandicae, Hydrocotyle novae-zelandiae var. montana, Aciphylla Colensoi, A. squarrosa (in a very wide sense), Gaultheria rupestris, Pentachondra pumila, Cyathodes Colensoi, Leucopogon Fraseri, Dracophyllum uniflorum, Suttonia nummularia, Gentiana corymbifera, Myosotis australis (probably distinct from the Australian species of that name), Pygmaea pulvinaris, Ourisia caespitosa, Euphrasia revoluta, E. zealandica, Pratia macrodon, Forstera Bidwillii, Phyllachne Colensoi, Celmisia Du Rietzii, C. discolor (= C. intermedia Petrie), C. spectabilis, C. viscosa, C. laricifolia, C. longifolia, C. Lyallii, C. Haastii, Gnaphalium Traversii, Raoulia grandiflora, Helichrysum bellidioides, Cassinia Vauvilliersii, Craspedia uniflora (in a very wide sense), Cotula pectinata, C. pyrethrifolia and Senecio bellidioides ore one of its near allies.

Fell-field vegetation occurs on all the dry mountains but on the wet mountains only on especially stony ground or on a substratum subject to strong erosion; it is absent in Stewart Island. Vertically, it occupies more or less of the subalpine and alpine belts, but, in ascending, the species decrease considerably in number, though a few, absent below, reinforce the depleted community. The greatest development of fell-field is on the dry greywacke mountains of South Island, but it must be emphasized that much is merely induced through the burning of tussock-grassland or Nothofagus forest.

Fell-field falls naturally into that of dry and of wet mountains. Naturally too, the ecological conditions supplied by these opposite classes differ considerably, but the fundamental factors governing the formation as a whole are everywhere similar. Foremost, stands out the unstable substratum due to frequent erosion, rapid or insidious, dependant upon rain and wind in relation to a more or less friable surface, or to readily-moved stony debris. Such a substratum is altogether hostile to a closed community, so the excess of bare ground readily becomes the sport of wind and water, while that bearing vegetation is easily undermined. Then, on exposed parts of the mountains, especially ridges, summits and slopes facing the full blast of the wind, only those plants which hug the ground or form dense cushions can exist, even though the substratum be stable enough. Also very shallow soil favours fell-field. The deep snow-covering of the alpine belt leads physically to erosion during its melting and ecologically to a growing-period of short duration and ice-cold water for the roots. The plants are continually exposed to frost, except in winter when lying under their covering of snow, and, though these frosts are not really severe, a plant may be frozen hard during the night and exposed to strong insolation early in the day. In short, fell-field conditions are less favourable for vascular plants than those of any other high-mountain habitat, shingle-slip excepted.

Coming now to the life-forms, the main classes and number of species to each class are as follows:—shrubs 60, semi-woody plants 54, herbs 116, page 296grass-form 47, rush-form 1 and ferns 4. With but few exceptions, the plants are of very low stature no less than 144 (51%) being prostrate or close to the ground, while hardly any of the remainder exceed 30 cm. in height, the greater part being much less. There are 28 cushion-plants but in the most exposed positions certain species, usually erect, assume that form or else are flattened to the ground. As for the erect species, 10 are tussocks and some 15 have rigid stems or leaves (Aciphylla). As for leaves, these are small in 200 species (71%), most being very small and 5 species are leafless and several, leafy elsewhere, almost leafless, and in nearly all the species which also occur in other formations their leaves are reduced considerably beyond their average size. With regard to texture, nearly all the species have coriaceous, thick, hard or stiff leaves and those of the grasses are rolled. In fact, fell-field plants stand in harmony with the violent, frequent, long-persisting winds.

The life-history of fell-field is fairly clear and on most mountains its beginnings, its prime, and its destruction can be seen. Its earliest stage is the sparse colonization by xerophytes — some coming from neighbouring rocks — of stony debris (e. g. margin of shingle-slip) so soon as this is sufficiently stable. In course of time, should nothing upset this stability, a small amount of humus will accumulate, the stones themselves will break up into fine particles, fairly good seed-beds will be established, particularly through the incoming of mat-plants, and species from tussock-grassland or herb-field can enter the community; indeed, if stability is maintained, as on the flattest ground, well-watered by melting snow, or in hollows where snow lies long, considerable patches of closed vegetation may be established — oases, as it were. On the contrary, the disintegration, ever in progress, renders fell-field far from long-lived it being in a constant state of destruction and renewal. A heavy snowfall is before all else the most powerful factor for damage on a large scale, since it leads to snow avalanches which tear up the surface destroying all vegetation and depositing the remains on the gully-floor hundreds of metres below. Seeds germinate well enough, when they get the chance, and in New Zealand at any rate it is not as Warming suggests (1909:256) a relation between seed-germination and climate that determines the openness of fell-field, but largely the disintegration factor.

At the present time, in lower-subalpine fell-field, though the associations look virgin enough, except for a few exotic species of no real moment, in many cases it is indigenous-induced as already explained. To cite a few examples of induced fell-field there is that of Porter's Pass (E.), Jack's Pass (NE.) and the lower subalpine slopes of Mount Ida (NO.).

β. Fell-field of the dry mountains or a specially dry substratum.

γ. Fell-field of the wet mountains.

This series of associations is distinguished from that of the dry mountains by the presence of plants of a more mesophytic character and by the absence, usually, of the most intense xerophytes.

The species number about 167 (families 30, genera 71); the commoner species are mentioned below. The life-forms are as follows: — shrubs 24, semi-woody plants 34, herbs 77, grass-like plants 28, rush-like plants 1, ferns 3.

The community, in large part, is a thinning out of the species of herb-field and tussock-grassland, together with the addition of certain plants usually rupestral and a few rare except in this class of fell-field.

The Tararua Mountains near the summits of their highest peaks on stony ground bear a fell-field association, consisting principally of the following: — Danthonia Raoulii var. flavescens, Ranunculus insignis, Anisotome dissecta, Hebe Astoni (cupressoid), green cushions of Phyllachne Colensoi, Celmisia hieracifolia (Fig. 83), C. oblonga, Raoulia grandiflora (Fig. 84) and Leucogenes Leontopodium (Fig. 63).

On Mount Egmont, with increase of altitude, the herb-field becomes more open until on scoria slopes plants are merely dotted about or far distant, the most important being Poa Colensoi, Luzula Colensoi, Epilobium glabellum var. erubescens, Claytonia australasica and Anisotome aromatica.

South Island wet mountain fell-field is virtually restricted to the North-western, Western, South Otago and Fiord districts. The vegetation is richer than that of dry mountain fell-field and the species far more striking. Thus the following Ranunculi are particularly, noteworthy: — R. insignis (NW.), R. Monroi (NW. but also on certain dry mountains), R. sericophyllus (W.) growing amongst large blocks of stone accompanied by the summer-green fern Polystichum cystostegia, R. Simpsonii (F.), R. Buchanani (SO., F.) and the hybrid swarm between the last two, R. Godleyanus (W. — Rakaia Basin to Mount Cook area), R. Grahami (W., Mountain Cook area), R. pachyrhizus (SO., F.). Generally the above are much dwarfed as compared with their herb-field form. The following also are characteristic: — Mar-sippospermum gracile (stiff, rush-like tussock, 20 cm. high), Microlaena Colensoi, Danthonia crassiuscula (small tussock with stiff somewhat horizontal leaves), Poa Cockayniana (large, thick mats), Uncinia macrolepis, U. fuscovaginata, vars. of Acaena Sanguisorbae and hybrids between them, Coriaria angustissima, C. lurida and hybrids between the two, Viola Cunninghamii, Carmichaelia grandiflora (in a wide sense), Epilobium glabellum, E. rubro-page 302marginatum (NW., W.), E. tasmanicum (in a wide sense), Aciphylla divisa, A. similis, A. crenulata (W.), Dracophyllum Kirkii, Suttonia nummularia, Hebe macrantha, Veronica Lyallii, Ourisia sessiliflora, Phyllachne Colensoi, P. clavigera, Celmisia sessiliflora, C. laricifolia, C. Du Rietzii, C. brevifolia, C. Bonplandii, Leucogenes grandiceps, Cotula pyrethrifolia, Raoulia Hectori (SO., south of W. on east), Senecio scorzoneroides and S. revolutus (SO., F.) forming wide mats.

The community occurs both in the subalpine and alpine belts. The substratum is too stony to allow the species to grow at all closely e. g. shingle-slip of large stones fairly stable, which forms a broad path from the alpine stony ground to river-bed (Fig. 87) or glacier; firm talus below cliffs; old river-bed at the head of rivers from glaciers; stony ground in the alpine-belt. Evidently the subalpine area must be the richest in species and the vegetation merges into tall tussock-grassland and herb-field. Various mat-forming species of Celmisia are frequently physiognomic. In the Western district, Leucogenes grandiceps may form great silvery mats on debris near the base of alpine cliffs.

In the Fiord district silvery mats of Celmisia Hectori may dominate, accompanied by abundance of the glaucous, cut-leaved Ranunculus Buchanani, the pale-lemon flowered R. Simpsonii and their many hybrids. An allied association on Rough Peaks (west of SO.) is thus vividly described by G. Simpson and J. S. Thomson (1926:375). "At about 5000 ft. altitude large flat stones almost completely cover the ground, and there Celmisia Hectori formed an almost pure association, the plants growing in between and over the stones, so that for many acres nothing is to be seen except C. Hectori and the protruding stones, with occasional plants of Abrotanella inconspicua, Celmisia Haastii, Marsippospermum gracile, Phyllachne Colensoi and Senecio revolutus. A few plants of Aciphylla similis and A. Spedeni were also present, but very few. This association is most striking: the great sheets of glistening silvery leaves of the Celmisia framing the grey flat rocks and shining in the sun made a sight never to be forgotten."

In the North-western district there is a remarkable montane plant-association which occurs on the plateau extending from near the coal-mining township of Denniston and rising gradually to the slope of Mount Rochfort, its lowest level being about 600 m. Owing to the plateau being exposed to the full face of the westerly wind from the Tasman Sea, it is without forest notwithstanding a very high rainfall. The substratum is flat, rocky or paved with small stones or, in places sandy or clayey and sticky; rocks of various sizes stand out here and there. The plants are all flattened closely to the ground: they root in the chinks between the stones; there is far more bare ground than vegetation. Where large rocks supply shelter, shrubs prostrate in the open grow more or less erect and even Nothofagus page 303cliffortioides is present i. e. but for the wind there would be forest. The following, nearly all high-mountain plants, are the principal species: — Leptospermum scoparium (dominant), Dacrydium Bidwillii, D. laxifolium, Danthonia Raoulii var. rubra?, D. australis (a species of the alpine belt), Carpha alpina, Hypolaena lateriflora, Pimelea Gnidia or an unnamed species, a species of Dracophyllum allied to D. uniflorum, Cyathodes empetrifolia, Gentiana Town-soni, Donatia novae-zelandiae, Celmisia dubia and Senecio bellidioides.

α. General.

Grassland is that great group of associations — the largest of the high mountains — in which grasses dominate but where, at times, herbs play an almost equal part. The group falls into the distinct ecological classes of tussock-grassland and mat-grassland — this quite limited in extent —, and the former naturally divided into tall and low, as already defined for the lowlands.

It is not feasible to supply definite figures regarding the floristic composition of grassland since, as will be seen, it is a matter of opinion whether to include tall tussock-herb field in herb-field or in the group under consideration. Therefore, I am giving a rather low estimate which omits those species belonging mainly to associations grasslike in physiognomy but herb-field in content.

The number of species admitted here is 249 which belong to 39 families and 104 genera, the largest being as follows: — (families) Gramineae 56 species, Compositae 43; (genera) Danthonia 14, Celmisia 12, Poa 11, Acaena 10, Ranunculus 9 and Carex and Epilobium 8 each — 4 hybrid swarms are included, but many are omitted, and rather more than half the species belong also to fell-field. The most common species are cited when dealing with the communities.

Grassland, though abundant on all mountains, is most in evidence where forest is wanting. At the present time, its area is much smaller than in primitive New Zealand, since burning and grazing have eradicated the grasses and left behind the non-inflammable and unpalatable species most of which belong to fell-field, the latter, as an indigenous-induced community having replaced the grassland. Where forest is absent, high-mountain grassland is merely a continuation upwards of that of the lowland-lower montane belt, the main difference in the former being the dropping-out of a few lowland species and the gradual, or sometimes sudden, incoming of true high-mountain plants. Grassland requires a more "fertile" soil than fell-field and attains its greatest development on a clay substratum with more or less humus on the surface; indeed, the tussocks themselves gradually supply the latter.

The amount of rain required is different for different classes of grass-page 304land but, the higher the rainfall the larger the herb-field content. The ordinary high winds of the mountains and extreme insolation are not antagonistic, but snow lying to a great depth and for a long period is more or less harmful.

The life-history of grassland has been discussed when dealing with lowland-lower montane grassland. In the upper subalpine and alpine belts grassland appears to be a succession following fell-field dependant on increase in the average stability of the substratum. Once tussocks are established, their humus-making power comes into play and species other than those tolerating fell-field conditions can gain a footing. On the other hand, the tussocks themselves will increase in quantity and eventually make the entrance of further species difficult, the tussock-form being a dominant climax-form just as is the tree-form in forest. Nor are these two forms, so distinct in themselves, as ecologically different as one might think since both are strongly hostile to light-demanding species.

β. Low tussock-grassland.

γ. Tall tussock-grassland.

δ. Mat-grassland.

General.

Bog associations are those in which more or less Sphagnum is nearly always present, together with some of the following species: — Gleichenia alpina, Dacrydium laxifolium, Carpha alpina, Oreobolus pectinatus, Carex Gaudichaudiana, Eypolaena lateriflora, species of Gaimardia, species of Drosera, Halorrhagis micrantha, Liparophyllum Gunnii, Phyllachne Colensoi, Donatia novae-zelandiae, Celmisia glandulosa and Olearia virgata.

The number of species for the high-mountain part of the formation is 138 which belong to 33 families and 77 genera, the largest being Compositae 15 species, Cyperaceae 14 and Epacridaceae 9, but none of the genera exceed 6 species. Those most widely spread appear in what follows.

Bog occurs throughout all the high-mountain area wherever the drainage is insufficient to forbid water lying on the ground for considerable periods. Usually the bogs are small. The habitat is not governed principally by rainfall, for bogs occur both where such is heavy and where it is quite light; in the latter case, the bog-community depends upon the substratum being in close proximity to streams liable to flood or springs and shallow lakes. On the contrary, in an extremely wet climate, bogs may originate page 322on flat ground distant from streams &c., for, m such a climate Sphagnum can become established on steep slopes and other unlikely places.

As to the life-forms of the species, there are 29 shrubs, 11 semi-woody plants, 65 herbs, 23 grass-like plants, 6 rush-like and 4 ferns. Most of the shrubs are prostrate, even if usually erect elsewhere, e. g. Leptospermum scoparium, Olearia virgata; cushion-plants number 11.

A bog-association may be a succession following swamp; primary succession culminating in tussock-grassland, herb-field or shrubland; or even a climax where the water-supply is constant. In some measure the permanency of the bog depends upon the ability of the sphagnum by its upward growth to bury the invading grasses, herbs and shrubs. If these grow faster than the moss the latter is doomed. Thus, small bogs are rapidly transformed into grass, herb and shrub associations, as in the case of one I have known on Jack's Pass (NE.) for some 25 years and noted getting gradually smaller and smaller. A closed community of Celmisia coriacea and Astelia Cockaynei in its vicinity was originally Sphagnum bog.

Various classes of bog.

Schoenus pauciflorus bog is extremely common in the montane-subalpine tussock-grassland area of South Island and it occurs also to some extent on the Volcanic Plateau but as a somewhat different association. The reddish colour of the Schoenus tussocks in contradistinction to the brown grass renders the community conspicuous even from a distance. Although the bog is traversed by running streams, the ground is sopping wet. Sphagnum cushions are usually plentiful and growing on them certain small herbs, e. g. Blechnum penna marina, species of Drosera, Geranium microphyllum, Viola Cunninghamii, Haloorhagis micrantha, Nertera Bal-fouriana and Celmisia longifolia var., Chrysobactron Hookeri var. angustifolia is usually abundant.

Closely related to the above in the North-eastern and Eastern districts are associations where Schoenus is not dominant, Sphagnum abundant and shrubs present e. g. Leptospermum scoparium, Gaultheria depressa, G. rupestris, Dracophyllum uniflorum, Hebe buxifolia and Cassinia Vauvilliersii. Astelia Cockaynei is frequently an important feature. In many places, Carex Gaudichaudiana dominates. More or less Danthonia Raoulii var. rubra is usually present, but rather as an invader from the grassland surrounding the bog than as a true member of the community.

Cushion-bog, so-called from the abundance of that life-form in the associations, is common in the subalpine-belt of many South Island wet mountains. The bog is usually quite small. The special feature is the numerous, small, dense cushions of the following, some of which may be absent: — Oreobolus pectinatus, 0. strictus, Gaimardia ciliata, G. setacea, Phyllachne clavigera, P. Colensoi and Donatia novae-zelandiae. In addition most of the following will be present: — Gleichenia alpina, Dacrydium laxifolium, bushes of D. Bidwillii, Carex Berggreni (SO.), Carpha alpina, Hypolaena page 323lateriflora, Astelia linearis, species of Drosera, prostrate Leptospermum scoparium, Plantago triandra, Pentachondra pumila, Cyathodes empetrifolia, C. pumila, one or more species of Gentiana, Celmisia longifolia var. alpina or other variety and C. glandulosa var. vera. The extensive bog association of the upper Routeburn hanging valley is of this class and, in addition to most of the above are Hebe buxifolia var. paucibrachiata and H. Hectori, Sometimes, especially in open places in subalpine forest, prostrate Dacrydium Bidwillii, is physiognomic and stunted Nothofagus cliffortioides common.

Hypolaena-Gleichenia bog is another type. It greatly resembles the allied bog of the lowland belt. Bog of this character occurs on the Volcanic Plateau, but its presence depends upon abundant ground-water supplied by melting of the winter snow since the drainage is good. Gleichenia alpina is plentiful but the grass-like Carpha alpina with its pale-green leaves, withered and twisted at their extremities, is the special feature. There is abundance of Oreobolus pectinatus, Viola Cunninghamii and Celmisia glandulosa var. vera. In the same district where the conditions are truly boggy the dark-green Liparophyllum Gunnii forms close mats together with a turf of Carpha alpina, Scirpus crassiusculus, S. aucklandicus and Gnaphalium paludosum. Utricularia monanthos is extremely plentiful. Other common plants are Danthonia Raoulii var. rubra, Juncus antarcticus, Carex ternaria, Aciphylla squarrosa, Gentiana bellidifolia, Coprosma repens and Craspedia minor. Better drained, though constantly wet ground, brings Hypolaena and Gleichenia into dominance accompanied by abundance of Hebe buxifolia, and many fell-field shrubs much dwarfed are raised on drier mounds above the general level.

Hypolaena bog on the Rahu Saddle (NW.) is distinguished by the abundance of bushes of Dracophyllum palustre forming patches about 90 cm. long and about 60 cm. high of its slender twiggy, blackish, crowded branches; also Cyathodes empetrifolia is conspicuous and there is some Phormium Colensoi.

Water communities.

Here are included associations of running and still water and those of flushes, but excluding those of dripping rocks. The species number only 11 which belong to 8 families and 9 genera.

Where streams flow swiftly Algae and perhaps a moss or two are present, their presence on stones marking the usual depth of the water. In winter many glacial streams, even of considerable size, are quite dry and during the rest of the year the amount of water varies greatly. Montia fontana is characteristic and often fills small, shallow brooks, even floating upon the surface or forming close cushions in shallow, fairly rapid streams (Fig. 93). Epilobium macropus — physiognomic from its large flowers — is common in shallow parts of slow-flowing subalpine brooks and in shallow water of depressions in river-beds, a station likewise of Claytonia australasica. page 324In South Island on margins of montane streams reddish tussocks of Carex Buchanani grow in abundance. On the Volcanic Plateau and in many parts of South Island, Gunnera dentata forms close masses in very shallow water and on the wet ground adjacent, its leaves flattened to the soil excluding other plants. In many South Island shallow streams, there is a close growth of the slender-stemmed Schizeilema nitens distinguished by its small shining, trifoliolate, thin, glabrous leaves. Ranunculus Cheesemanii (NE., north of E.) is frequent in places where water generally lies. R. depressus, in a very wide sense, is common on still water. In fairly rapid brooks there is often a dense growth of Myriophyllum propinquum, the leaves submerged and on the water-surface float the brown leaves of Potamogeton Cheesemanii.

Soil constantly wet through water rising out of the ground is occupied by many species, of which the following are particularly common: — Carex Gaudichaudiana, C. Petriei, Scirpus aucklandicus, Juncus novae-zelandiae, Claytonia australasica, Acaena saccaticupula, Oxalis lactea, Viola Cunning-hamii, Epilobium pedunculare var. brunnescens, Pratia angulata, Plantago triandra, Gnaphalium Mackayi and species of Craspedia.

The associations of lakes and tarns differ but little from those of the lowland belt. The same species of Potamogeton and Myriophyllum are present and the swamp species of the margin are lowland plants, e. g. Heleocharis Cunninghamii, Cladium glomeratum, Carex subdola, C. secta, C. pseudocyperus. Isoetes alpinus and Pilularia novae-zelandiae, submerged aquatics, are probably common.

Swamp.

There is but little swamp of a high-mountain character. Carex virgata or C. secta are frequently dominant and C. ternaria, C. stellulata and C. diandra are extremely common. In the deepest water Typha angustifolia var. Muelleri dominates. On the margin, there is usually a bog community in which Plantago triandra and Isotoma fluviatilis may be plentiful.

Swamp occurs principally in montane valleys of South Island and owes its origin to frequent flooding of the ground by rivers and streams, especially during rapid melting of snow; where the drainage is insufficient, it is readily transformed into bog.