Vegetation of Mount Peel, Canterbury, N.Z.
Part 1.—The Forests and Shrublands.
[Read before the Canterbury Philosophical Institute, 1st October, 1924; received by Editor, 20th October, 1924; issued separately, 6th March, 1926.]
The present paper owes its inception to a statement by Cockayne (1917, p. 62), when discussing his proposed botanical districts: “The actual boundaries of many of the districts are extremely hard to fix, and in no few cases must always be artificial, though that detailed research which must take place in due course as phytogeographic workers increase in number will eventually find out the most natural limits.” Observations were made at all seasons during the period 1917–21, some thirty weeks being spent in the field, in the attempt to provide one such detailed study. I am deeply indebted to my friend and master, Dr. L. Cockayne, F.R.S., F.N.Z.Inst, &c., for his unfailing interest and encouragement in all my botanical work, and for his help and criticism during the investigation.
For some sixty-five years the grasslands of Mount Peel have been carrying sheep, and for a long period the river-flats have been grazed by cattle. The forests have been partially milled, and large portions have been felled and turned into arable or pasture land. Burning has been practised extensively on the grasslands, and fire has not altogether spared the forest. The destruction of the forest still continues, but fortunately a considerable area has been created a scenic reserve. Obviously the present facies of the vegetation must differ considerably from its primitive condition, and successions now in progress must differ greatly in most cases from those which produced the primitive vegetation. Admirably suited to the needs of students of such vegetation is the classification of associations given by Cockayne (1919, p. 147): (1) primitive, (2) modified, (3) indigenous-induced, (4) adventitious-induced, (5) artificial. I also follow Cockayne (e.g., 1921, passim) in his usage of the terms “formation,” “association,” “subassociation,” “colony.” The term “relic” I apply to fragments of communities that persist in the midst of associations that have reached a further stage in the succession—e.g., relic river-bed communities in tussock-grassland, relic beech forest in rain forest. Individual plants may also be relics of a community that has passed by—e.g., Polystichum vestitum, a relic of forest. In some cases it is difficult to decide whether a community is relic or indigenous-induced.
(b.) Physiography and Climate.
The area examined is some 11,000 ha. (27,000 ac.), having its centre in about 43° 52′ S. lat. and 171° 12' E. long., and is included in the Eastern Botanical District of the Southern Botanical Province, as delimited by Cockayne (l.c., 1917, p. 65). The Rangitata River from just below its gorge forms the eastern boundary for some 12 km. (7 ½ miles), and the
long gorge of the Orari forms the western boundary. The southerly-facing slopes arising from the plain, here 270 m. (886 ft.) above sea-level, reach 1,308 m. (4,291 ft.) in the peak of Little Mount Peel. Thence the crest of the ridge runs north-west, descending to 1,125 m. (3,691 ft.), and rising in the rounded mass here called Middle Peel to 1,585 m. (5,200 ft.), and culminating in the double peak of Big Mount Peel at 1,740 m. (5,709 ft.). The northern boundary is formed by streams running to the Orari and Rangitata from the saddle, 1,220 m. (4,003 ft.), immediately to the north of the summit. The southern boundary is formed by the remnants of forest on the plain. Numerous streams descend to both rivers from the ridge, several of the eastern ones joining to form the Lynn. On all these streams a series of waterfalls and miniature gorges occur. Small shingle-fans end the eastern streams, while the streams of the western slopes form small hanging valleys ending in waterfalls into the Orari. Both Big and Little Mount Peel are sharp in outline, with much-shattered rocky summits and numerous rock-buttresses, whereas Middle Peel is covered with finer debris and gives rise to fairly extensive screes (shingle-slips). The spurs leading to the main divide lie athwart the prevailing north-west winds, and have a higher average elevation as one proceeds along the ridge towards Big Mount Peel. The topography is thus of a youthful character, and offers varied habitats for plant communities. The main mass of the mountain is formed of the comparatively easily-weathered greywacke rock.
The outstanding climatic features affecting the vegetation are the rainfall, snowfall, and wind. Mount Peel lies within the rain-band of 760–1,020 mm. annual fall, which stretches throughout the South Island, narrow in Canterbury and broadening out in Marlborough and Otago. Peel Forest itself, however, has a somewhat higher mean annual rainfall, as shown in the following table, recalculated in millimetres from the Journal of the Canterbury Agricultural and Pastoral Association for 1918, 1919, and 1920. The mean value is stated to be derived from records of “a considerable number of years.”
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|1917||50 0||67 1||111.8||72.6||148.6||44.7||121 2||98 8||243 3||102.1||79 0||275 1||1,414 3|
|1918||132 9||128 5||101 2||32.3||16.8||66 6||26.4||87.6||80.5||122.4||141 0||122 4||1,066.3|
|1919||165.0||6 4||28 2||101.3||12 4||62 2||114.6||85.3||190.0||40.4||130 6||121 2||1,138 5|
|Mean||116 6||110 7||126.7||95.3||63.0||77 0||83.3||57.4||94.5||97 1||106 7||118 9||1,147.2|
The difference in rainfall over a period of nine years between Mount Peel Station, exposed to the dry north-west winds sweeping down from the Rangitata Gorge, and Peel Forest, sheltered in a basin of hills, is as follows: Mount Peel (mean), 960.15 mm.; Peel Forest (mean), 1,164.81 mm. Rain is fairly generally distributed over the year; any month may have a fall of over 150 mm., the average monthly rainfall being over 95 mm. In addition the number of cloudy days on the forested area is considerably in excess of that elsewhere. Speight, Cockayne, and Laing (1911) have sufficiently dealt with the influence of the Southern Alps on the rainfall and climate of the eastern ranges and plains. The influence of wind is dealt with later on.
From some 1,200 m. upwards on the Rangitata face of the mountain snow lies practically throughout the winter, though a strong north-west wind, even in midwinter, may temporarily clear the slopes in a remarkable manner. On the southern slopes the line of winter snow falls c. 200 m.,
and the snow remains much later in the season. From 1,200 m. down to 650 m. snow lies for weeks at a time on the southern face, and for lesser periods on the Rangitata face. Below this elevation snow may fall at any season, but usually lasts only a few hours. The great influence of snow upon the vegetation at Mount Peel will be clear from the detailed descriptions which follow, especially in regard to the formation of the belts.
Of the past climatic history of the area, most importance attaches to the post-glacial period. This has been dealt with by Speight (1911), and as to its botanical significance by Speight, Cockayne, and Laing (l.c., 1911, p. 343). During the period of glaciation the higher peaks of Mount Peel probably rose above the glacier-field as nunataks, and the special features of the summit vegetation, as well as more general questions raised, are dealt with later on.
(c.) The Formations and their Physiognomy.
The broad features of the plant-covering are due to the interaction of the major factors briefly discussed above: (1) Topography, (2) climate, (3) the glacial period, (4) the greywacke substratum. Great modifications have been caused by the advent of man, but the belts of vegetation still persist with a semi-primitive appearance and character. The lower slopes of Little Mount Peel from c. 600 m. downwards to the south-west, south, and south-east are clad in rain forest, which extends on to the upper plains, where it is now broken into fragments. Above the forest is an extensive belt of tall-tussock grassland, merging, on the Orari and Rangitata faces, below into low-tussock grassland, above into fell-field or herb-field, and finally into the open formation of the summit peaks. On the southern face the tall-tussock grassland merges below into a belt of Phormium Colensoi with Blechnum capense, in which Aciphylla Colensoi is prominent, thence by way of an interrupted belt of shrubland into the forest. Scattered through the tall-tussock grassland on the southern and western aspects occur more or less extensive patches of scrub, which, with the brown of Dracophyllum or the green of Hebe, diversify the tawny grassland. Lining the narrow stream-valleys are fringing forests, dark green below, and sage-green above owing to the groves of Gaya ribifolia, To the north especially towards the Orari, the slopes contain occasional dark masses of subalpine beech forest, merging above into scrub and then the shingle-slips. Below the terrace of the Rangitata lies its broad river-bed clothed in great stretches of gorse.
B. The Forests.
Both the main types of New Zealand forest occur at Mount Peel—the rain forest and southern-beech forest. The southern-beech forest belongs to the subalpine beech-forest association, with Nothofagus cliffortioides as its sole dominant and only tall tree. It is the climax forest of the eastern mountain-ranges of Canterbury. The rain forest groups naturally into two associations—that of the terrace lands, dominated by Podocarpus dacrydioides, P. spicatus, and P. totara in varying proportions according to the edaphic conditions, and that of the hill-slopes, characterized by the infrequence of the podocarps, by the lack of any dominance in general, and by the development of several distinct subassociations. This rain forest is in marked contrast with the southern-beech forest at similar
altitudes on Mount Somers (mean rainfall 857 mm.) and Mount Hutt (mean rainfall 1,048 mm.), and may be correlated with the more favourable conditions of sheltered situation and rather greater rainfall.
The composition of the rain forest as a whole is as follows: Pterid phyta—8 families, 19 genera, 43 species; Gymnospermae—2 families, 2 genera, 4 species; monocotyledons—6 families, 12 genera, 19 species; dicotyledons—31 families, 53 genera, 89 species. The Polypodiaceae have 24 species, Hymenophyllaceae 8, Rubiaceae 9, Compositae 10. Represented by 1 species each are 17 families. Of the 155 species, 23 may be classed as abundant, 71 as more or less common, 45 as occasional to infrequent, 16 as rather rare.
The growth-forms include 6 small tuberous-rooted herbs (5 summer-green, 1 saprophytic); 3 simple rosette herbs; 41 tuft plants (including 18 tuft-ferns, 6 tree-ferns, 9 grass-like herbs); 2 trailing herbs; 16 lianes; 26 creeping plants (8 patch-herbs, 3 mat-plants, 15 sheet-plants); 61 bushy plants (including 3 herbs; 1 semi-woody plant; 30 trees—3 tall, 8 medium, 19 small; 27 shrubs—14 open-branching, 4 fastigiate, 9 divaricating). There are thus 80 herbaceous species, 3 semi-woody, 72 woody. There are 15 ferns that occur as epiphytes, and 3 hemi-parasitic shrubs.
(b.) The Podocarp Forest.
The podocarp forest may best be described in two sections, though these merge into one another. On the flood-plain of the Rangitata at about 240 m. Podocarpus dacrydioides is dominant, with P. spicatus subdominant. Seen from above, this section presents a billowy appearance, P. dacrydioides reaching 27 m. and overtopping P. spicatus by some 4–5 m. P. totara is infrequent. Near the base of the terrace-slopes, where streams from the mountain and ooze from the terrace cause a development of swampy ground, we get true but limited P. dacrydioides swamp forest. Wintera colorata is abundant, often attaining 9 m. Below there is a dense under-growth, which may be mainly juvenile P. dacrydioides, or contain varying amounts of Wintera colorata, Coprosma rotundifolia, Melicytus micranthus, Myrtus pedunculata, Griselinia litloralis. These are largely covered with lichens, liverworts, and mosses. On the floor and scrambling over the shrubs are occasional Rubus schmidlioides. The floor-plants are Uncinia uncinata, Nertera dichondraefolia, Blechnum discolor, Microlaena avenacea, Hymenophyllum demissum, but only where there is not an excess of water. Climbing up the trees is much Cyclophorus serpens. Near streams other shrubs occur, notably Carpodetus serratus, Schefflera digitata, Fuchsia excorticata, Nothopanax arboreum, Hebe salicifolia var. communis. Ferns are more numerous, and include Blechnum fluviatile, B. lanceolatum, Asplenium bulbiferum, Polypodium diversifolium. Here, too, occur Ptero-stylis Banksii, Stellaria parviflora, Pratia angulata, and other herbs. Where the floor becomes drier the ground-plants are mainly Astelia nervosa, Poly-stichum vestitum, Asplenium bulbiferum. Suttonia australis becomes a common undergrowth shrub, and here P. spicatus is subdominant, while Elaeocarpus Hookerianus, Nothopanax arboreum, and Pennantia corymbosa become common; Asplenium flaccidum, Polypodium grammitidis, Cyclophorus serpens occurring on them. There will be odd Dicksonia fibrosa On the steep terrace-slopes P. totara enters in, and the association merges into the next section characteristic of the upper terrace-flats. In general P. spicatus is dominant, with P. totara, and P. dacrydioides in lesser
amounts. Here and there, but little inferior in height to the podocarps, is Elaeocarpus Hookerianus. The second layer is composed of Grisedinia littoralis, Nothopanax arboreum, Schefflera digitata, Carpodetus serratus, Pittosporum tenuifolium, with the usual fern epiphytes. The shrub layer is mainly made up of Wintera colorata, Coprosma rotundifolia, C. rhamnoides, Fuchsia excorticata, Aristotelia serrata. Metrosideros hypericifolia creeps over the ground and climbs high among the trees. The chief floor-plants are Polystichum vestitum, Uncinia uncinata, U. riparia, Blechnum discolor, Polypodium diversifolium. There are numerous seedlings, especially par-sonsias and podocarps. On the outskirts is a tangle of various Rubi, Calystegia tuguriorum, Parsonsia heterophylla, Clematis indivisa, C. foetida, and Metrosideros hypericifolia, the last especially abundant.
Where the floor is low-lying and damp the association closely resembles the flood-plain section, and in gullies merges into the hillside forest. On the drier ground, even when the ground is only slightly higher, P. dacrydioides practically disappears, being replaced by P. totara. This becomes dominant on the driest areas. Here Suttonia australis, Pennantia corymbosa, Hoheria angustifolia, Plagianthus betulinus, Edwardsia microphylla become common in the second layer, with occasional Melicytus lanceolatus, and more or less Pseudopanax crassifolium var. unifoliolatum, Coprosma linariifolia, Melicytus ramiflorus. Melicope simplex, Nothopanax anomalum, and to a less extent Fuchsia Colensoi and Coprosma areolata enter the shrub layer. On banks and stony places occur Asplenium flabellifolium, A. Hookerianum, A. flaccidum, and occasionally Lycopodium rolubile, and sheets of Hydro-cotyle americana, H. moschata, Schizeilema Hookeri. On the forest-margin Senecio sciadophilus is added to the lianes.
2. Plagianthus betulinus Subassociation.
Plagianthus betulinus is known to form indigenous-induced associations, but the community at Mount Peel appears to be a remnant of a primitive subassociation, as the trees are adult, up to 15 m. tall, and reach 0.6 m. diameter at 1 m. from the base. The community now occurs only in certain fragments, and is much modified owing to the isolation of the fragments and the intrusion of stock. Besides the dominant tree, there are less amounts of large Griselinia littoralis and Hoheria angustifolia, with occasional adult Pseudopanax crassifolium var. unifoliolatum and Fuchsia excorticata. The undergrowth is made up of Coprosma linariifolia, Melicope simplex, Pseudopanax crassifolium (juvenile), with the usual lianes. The shrubs are sparse, and the floor is clothed mainly with exotic species, of which Poa pratensis, Holcus lanatus, and Dactylis glomerata are the chief. Where the undergrowth is dense the grass covering is replaced by Poly-stichum vestitum and odd seedlings, mainly parsonsias, Suttonia australis, Griselinia littoralis, Pittosporum tenuifolium.
(1.) Milled Forest.—Forest that has been milled has two characteristic features : (i) The entry of various aliens, especially those of the “berried” type—e.g., Hypericum Androsaemum and Rubus fruticosus; (ii) the rapid growth of certain of the smaller trees and shrubs. Aristotelia serrata often forms thickets of slender stems 5–6 m. tall, Fuchsia excorticata also increases greatly, while Wintera colorata and Carpodetus serratus grow into small trees. Lianes often increase greatly and convert the forest into an almost impenetrable mass. Hoheria angustifolia does not increase markedly in such forest. Where cattle enter milled forest
open spaces increase and the forest becomes separated into clumps. Of especial attraction to cattle are Uncinia spp., Carex spp., and to a less extent Microlaena avenacea. Certain shrubs—e.g., Schefflera digitata, Nothopanax arboreum—are also fed on. Where cattle do not penetrate, seedling podocarps and other species of the original forest become established, and the forest progresses towards its previous condition.
(2.) Succession to Podocarpus dacrydioides.—The succession from swamp to Podocarpus dacrydioides may be traced in places adjacent to the adult podocarp association. P. dacrydioides and Griselinia littoralis establish themselves in the swamp, which has Olearia avicenniaefolia, Coprosma spp. on its margin, and in some cases Olearia virgata var. and O. lineata are members of the swamp community. P. dacrydioides becomes dominant and forms thickets. The following description of the progress of such thickets is taken direct from my notes: The P. dacrydioides are here some 30–50 cm. apart, have a basal diameter of ± 12 cm., and a height of 9–14 m. The tall slender trunks are sparsely clad with short branches, and end in a small canopied head of foliage. The shrubs are few and poorly developed, and include Suttonia divaricata, Coprosma rotundifolia, Wintera colorata, C. parviflora, Pseudopanax crassifolium var unifoliolatum (juvenile), with rather larger Griselinia littoralis. These occur only on the patches of rather drier ground. Beneath is much Carex secta (Blechnum capense on it), Astelia nervosa, and, where the shrubs occur, some Polystichum vestitum. On the outskirts Rubus australis climbs to the top of the trees. Between the herbs of the floor are pools of water, slow-flowing streams, or boggy ground.
(3.) Succession to Hoheria angustifolia.—There are occurring on the felled areas two distinct successions—to Poa caespitosa grassland, and to IIoheria angustifolia thickets. The former is in a very early stage, the tussock grassland forming at present only clumps of varying size scattered here and there on the artificial grassland. The second is a characteristic feature of the grassland. The scattered clumps of Hoheria angustifolia are found in all stages from an open community of juvenile plants of the usual divaricating form to groves of adult trees in closed association. By the time the hoherias are assuming adult form above the community becomes so dense as to form thickets, in which seedlings of the following species become more or less common: podocarps, Edwardsia microphylla, Pennantia corymbosa, Elaeocarpus Hookerianus, Fuchsia excorticata, with various coprosmas. As these develop, the groves assume the form of young mixed forest. This stage is especially well developed as a defined margin to the existing forests in certain places. Polystichum vestitum, a relic from the original forest, increases greatly in amount, and other ferns and the lianes become plentiful. On the low-lying damper areas Podocarpus dacrydioides enters with the Hoheria, and early on becomes physiognomically important. On the drier stony ground sheep penetrate the clumps as the divaricating stage passes away, use them as camping-places, destroy the undergrowth, and induce a grassy ground-vegetation.
(c.) The Forest of the Mountain-Slopes.
The mixed podocarp forest gradually merges into the forest that clothes the slopes and fills the gullies of Little Mount Peel up to about 600 m. As one ascends, Podocarpus dacrydioides disappears almost at once, soon followed by P. spicatus; but occasional examples of P. totara occur through-out—large by stream-sides, dwarfed on slopes and ridges. The general
groundwork is made up of the following species in greater or less abundance: Griselinia littoralis, Nothopanax arboreum, Pittosporum tenuifolium, P. eugenioides, Edwardsia microphylla, Aristotelia serrata, Hoheria angusti-folia, Melicytus ramiflorus, Leptospermum ericoides, Metrosideros lucida, Fuchsia excorlicata, Pseudopanax crassifolium var. unifoliolatum, Suttonia australis, Olearia avicenniaefolia. The most common shrubs of the undergrowth are Wintera colorata, Nothopanax simplex, Suttonia australis, Suttonia divaricata, Coprosma rotundifolia, C. rhamnoides, C. linariifolia. All the lianes occur except Senecio sciadophilus, Rubus australis being usually in great abundance. The chief floor-plants are Polystichum vestitum, Blech-num discolor, B. capense, Asplenium bulbiferum, Polypodium diversifolium, Uncinia uncinata, U. riparia, Astelia nervosa. Seedlings of the common trees are usually numerous.
By stream-sides there is a greater variety and abundance of ferns, and Schefflera digitata, Aristotelia serrata, Fuchsia excorticata become prominent, the latter often being so plentiful as to be of distinct physiognomic importance, especially in its leafless winter condition. Hebe salicifolia var. communis and Gaya ribifolia are almost confined to the stream-side, and, as one ascends, Olearia arborescens, Nothopanax Colensoi, Senecio elaeagni-folius (as an open spreading small tree) become noteworthy. Pittosporum eugenioides is rare in or absent from the stream-side vegetation. Along the actual stream Hymenophyllum spp. are specially abundant, and here occur Epilobium rotundifolium, E. linnaeoides, Erechtites glabrescens, Myosotis Forsteri, Australina pusilla, Pratia angulata, Corysanthes macrantha. Steep banks are clad in sheets of Blechnum Patersoni, B. capense, Hymenophyllum demissum, H. multifidum, and H. peltatum. In places occur numerous Hemitelia Smithii, and logs, trunks of trees, and shrubs are clothed in epiphytes, mainly Hymenophylla and various ferns, liverworts, and mosses. Locally Alsophila Colensoi is prominent among great sheets of Blechnum capense.
The streams of the Lynn Valley are characterized by abundance of Helichrysum glomeratum. Hebe leiophylla, Veronica Lyallii, and the presence of Notospartium torulosum, Veronica linifolia, Olearia fragrantissima and in places much Senecio bellidioides. Stream-side rocks and rocky walls have Hymenophyllum pulcherrimum and Lycopodium Billardieri in addition to the ferns already mentioned. Where small rocky outcrops occur on the forest-floor Polypodium diversifolium, Cyclophorus serpens, and Rubus australis are common, and, if the crevices contain much soil, Asplenium Hookerianum, A. flabellifolium, A. Richardi.
Vertical rock-surfaces exposed to sun and wind have scattered Olearia avicenniaefolia, Helichrysum Selago, Hebe amplexicaulis, Danthonia setifolia, Coprosma brunnea, Notospartium torulosum, Dichelachne crinita, Agropyron scabrum var., not always all together. Some shaded rock-surfaces are clad in Angelica montana, Lycopodium Billardieri, Veronica Lyallii, and green tussocks of Schoenus pauciflorus, or breadths of Corysanthes macrantha among moss, where water drips.
Spurs and ridges are either occupied by the subassociations later described, or have as the most numerous plants Leptospermum ericoides, Suttonia australis, Metrosideros lucida, Nothopanax arboreum, Coprosma linariifolia, a large-leaved form of Myrtus pedunculata and Edwardsia microphylla. The undergrowth is mainly Suttonia australis, Coprosma rhamnoides, and in the upper portions Nothopanax simplex. The floor is rather sparsely clothed, mainly with Blechnum capense (stunted), Astelia nervosa, Uncinia uncinata, U. riparia, U. caespitosa, U.filiformis, Lycopodium volubile At the upper limits the association is invaded by members of the
fringing scrub—e.g., Dracophyllum longifolium (reaching a stature of 1.5 m., with spreading branches clothed .at the tips with rosettes of leaves of juvenile form, in which condition it flowers freely), Astelia Cockaynei, Phormium Colensoi, Leptospermum scoparium, Cassinia Vauvilliersii, C. fulvida var. montana, Gaultheria rupestris, and various small herbs, notably Celmisia spectabilis, Senecio bellidioides.
Where the ridges broaden out as they descend on to the terrace lands, plants of the stream-side creep upwards, and the undergrowth is mainly Coprosma rotundifolia, Wintera colorata, and Fuchsia excorticata. Here occurs the chief development of the tree-ferns Cyathea dealbata, C. Cunninghamii, and Dicksonia squarrosa, with a wealth of Asplenium bulbiferum, Leptopteris hymenophylloides, and Blechnum discolor.
(1.) Leptospermum ericoides Subassociation.—On many of the spurs on the southern slopes is developed a distinct subassociation with Leptospermum ericoides dominant and often the sole tree. Seen in the flowering season, these spurs stand out against the dark background of the general mass like the veining of a vast leaf. The Leptospermum averages 15 m. in height, and has a long trunk crowned by a small semifastigiate head, forming with its neighbours a dense canopy. While most of the shrubs may be present, Suttonia australis is usually very abundant, along with Coprosma rhamnoides and C. parviflora. In places Cyathodes acerosa, elsewhere rather rare at Mount Peel, predominates, with it being usually Gaultheriq, antipoda vars. At its upper limits the association has an undergrowth mainly of Nothopanax simplex, with stunted Griselinia littoralis and Olearia arborescens prominent. The floor-plants are the same as those for the ridges in general, but also include Blechnum penna marina, Cotula squalida, and Lagenophora petiolata.
In some places the association appears to be decadent, with many fallen trunks and dead or dying trees. In such places Blechnum discolor is plentiful, and juvenile Metrosideros lucida occurs in varying numbers. The association descends towards the streams of the western faces of the ridges, but on the eastern faces is rapidly succeeded by the general mixed forest.
(2.) Metrosideros lucida Subassociation.—This occupies considerable areas on rocky knolls and on slopes with a western aspect, and may be recognized from afar by its uniform sombre colouring, or in a good flowering season by its masses of red blossom. On the knolls the Metrosideros is youthful, and there is evidence that it is successional to the Leptospermum subassociation. The Metrosideros is the sole tree, c. 7 m. high, of a semifastigiate habit, much branched from the base, with slender naked branches each carrying a small canopied head of foliage, the whole forming a dense cover. The undergrowth is similar to that of the Leptospermum association, and is usually sparse. At the lower elevations Coprosma linariifolia is occasional, as tall as the Metrosideros, with trunks c. 13 cm. diameter. At the higher elevations occurs rarely small Libocedrus Bidwillii. On the slopes the Metrosideros is often adult, and the floor has a close cover of well-grown Blechnum capense with frequent Alsophila Colensoi, or uear streams the Blechnum may be replaced by sheets of luxuriant Gleichenia Cunninghamii, forming almost pure colonies.
(3.) Nothofagus cliffortioides Association Relic.—At an elevation of some 510 m.—i.e., near the upper forest-margin—and at stream-junctions at a lower elevation, in a few places, occur small patches of Nothofagus cliffortioides forest quite distinctly marked off from the surrounding forest-mass. The
communities appear to be relics from a more widespread association that has been replaced by the rain forest. The association as developed on the knolls contains Nothofagus cliffortioides as the sole tree. The trees, averaging 12–15 m. high, with trunks up to 50 cm. diameter, form a dense canopy, under which the undergrowth is scanty, consisting of odd stunted Suttonia australis, Metrosideros lucida, Nothopanax simplex, Coprosma microcarpa, Melicope simplex, Gaultheria antipoda, Leptospermum ericoides, Cyathodes acerosa, scattered widely. At the junction with the rain forest many of the rain-forest shrubs occur. The floor-plants are also sparse and stunted, and include Astelia nervosa, Pteridium esculentum, Blechnum capense, Polypodium diversifolium, Celmisia spectabilis, Elytranthe flavida is occasional. Seedling beeches are absent. Other examples of the community are reduced to a few old decadent trees amidst the incoming rain-forest species.
In the examples occurring at stream-junctions the floor is often covered in Dicranoloma moss-cushions, the trees are more youthful, with odd old decadent trees, and a litter of old trunks and broken limbs. Seedling beeches are very infrequent. Coprosma rhamnoides, C. parvifiora, C. microcarpa, Aristotelia fruticosa, Suttonia australis, Cyathodes acerosa, Helichrysum glomeratum are the commonest shrubs. Elytranthe flavida is fairly common, and Botrychium australe is common in several forms. Other occasional floor-plants are Polystichum vestitum, Uncinia uncinata, U. riparia, Blechnum capense, B. penna marina, Polypodium diversifolium.
(4.) Melicytus ramiflorus Subassociation.—At the Lynn Valley Melicytus ramiflorus forms subassociations, especially on westerly-facing slopes. The Melicytus becomes a good-sized tree (some specimens reaching a height of 11 m. with a diameter near the base of c. 50 cm.), usually much branched from near the base. Scattered among the Melicytus are occasional Edwardsia microphylla, Plagianthus betulinus, Hoheria angustifolia, Griselinia littoralis, Nothopanax arboreum. Undergrowth is very scanty indeed, there being little else but Suttonia australis and Griselinia littoralis. As one ascends the gullies the association merges into the mixed forest. The floor is stony and bare. The herbs are distant and small, mainly Pellaea rotundifolia, Asplenium flabellifolium, A. bulbiferum, Polypodium diversifolium, Astelia nervosa. Seedling Melicytus and Edwardsia are frequent.
(5.) Gaya ribifolia Association.—At the upper margins of certain gullyforests, and as isolated patches at higher elevations c. 750–900 m., occur groves of Gaya ribifolia, which elsewhere is an occasional member of stream-side forest. The association occurs on stony ground by stream-sides where there is a certain degree of shelter from strong winds. The Gaya is the sole tree (averaging 5 m. in height), and beneath is usually little but scattered Hypolepis Millefolium, Polystichum vestitum, Blechnum penna marina, and sometimes Coprosma propinqua, C. parviflora, C. ramulosa, Hebe buxifolia var. odora. With a less dense cover the shrubs become more numerous. The groves form a marked physiognomic feature, bare of foliage in winter, white with blossom in summer, sage-green at other periods. The association is somewhat xerophytic in character, and is not a part of the rain forest, being treated here merely for convenience.
(1.) Aristotelia serrata Succession.—This indigenous-induced association is well known as a successional stage towards regeneration of forest that has been destroyed by fire, and presents no special features at Mount Peel. It occurs in several places on the lower slopes where fire has run up from
the felled bush below. The Aristotelia forms dense thickets of tall slender stems (5–8 m. high), and contains a good deal of Fuchsia excorticata of small size. As shrubs, occur Wintera colorata, Melicytus ramiflorus, Suttonia australis, Coprosma rotundifolia. Blechnum discolor and Polystichum vestitum are more or less abundant, sometimes replaced by Blechnum capense. Rubus australis and Muehlenbeckia australis are frequent. Old Griselinia littoralis is almost the sole survivor from the original vegetation. Seedlings of many of the mixed-forest plants are frequent. On the damper slopes Fuchsia excorticata is subdominant.
(3.) Leptospermum ericoides Succession.—Thickets of Leptospermum ericoides occur on the more sunny slopes, both after burnt forest, and after sown grassland on felled areas. In the first case the ground is rapidly clothed in dense young Leptospermum, in which various seedlings get a root-hold, notably Pittosporum tenuifolium, Griselinia littoralis, Nothopanax arboreum, Suttonia australis, Carpodetus serratus, Pseudopanax crassifolium var. unifoliolatum, Hebe salicifolia var. communis, with Rubus australis, Coprosma rhamnoides, C. parviflora, and various ferns. Examples are met with where these forest species are beginning to dominate the Leptospermum.
On the artificial grassland the succession takes a different course where Polystichum vestitum survives the burning, its tussocks gradually overshading the grasses and other exotic and indigenous herbs. Fuchsia excorticata, F. Colensoi, Hoheria angustifolia are early comers along with the Leptospermum (both L. scoparium and L. ericoides), and Rubus australis forms mounded heaps. With the dominance of Leptospermum, thickets resembling the first described are reached.
(4.) Minor Successions.—In the Melicytus ramiflorus subassociation not infrequently patches are broken down by winter snows. In such places Rubus australis, Muehlenbeckia australis, M. complexa, and Calystegia tuguriorum rapidly form dense tangles. Growing up through such tangles are to be noted Hebe salicifolia var. communis, Plagianthus betulinus, Edwardsia microphylla, and Griselinia littoralis, which gradually assume dominance.
In several of the gully-forests more or less extensive slips have started successional movements. The actual course of events varies somewhat according to the nature of the surface exposed, the aspect of the slope, and the surrounding vegetation.
On the drier sunnier slopes early comers are Epilobium pedunculare, E. microphyllum, Gnaphalium collinum, Erechtites quadridentata, and Pteridium esculentum. Poa caespitosa, Danthonia semiannularis, D. pilosa, Dichelachne crinita, and various exotics, especially Verbascum Thapsus, Hypochaeris radicata, Rumex acetosella, come in. Early shrubs to establish are Olearia avicenniaefolia, Fuchsia Colensoi, Hebe salicifolia var. communis, Pittosporum tenuifolium, and the exotic Leycesteria formosa. Lianes capable of forming mounded heaps—Muehlenbeckia australis, M. complexa, Rubus australis, R. cissoides, R. subpauperatus—-are more or less common.
On damper slopes the sequence is more rapid, and Coriaria sarmentosa and Griselinia littoralis are prominent, as are Acaena Sanguisorbae var. pusilla and Calystegia tuguriorum. Trees of the neighbouring forest establish more rapidly.
(d.) Subalpine Southern-Beech Forest.
This forest is quite isolated from the rain forest, and occurs at higher elevations on the slopes of ridges leading down to the Orari. The sole tree is Nothofagus cliffortioides, many of large size, with trunks up to 1 m. or more in diameter. The largest trees are decadent, with projecting dead branches and excessive amounts of Elytranthe flavida. Quite striking is the absence of seedling and juvenile beeches. As one ascends, the trees
become smaller, and near the crests of the spurs are quite dwarfed owing to exposure to wind. The forests are accessible to sheep, which use them as shelter, and have probably caused the undergrowth to be sparser than in the primitive condition. There are occasional Coprosma linariifolia, C. parviflora, Aristotelia fruticosa, and more rarely C. microcarpa. On the floor are odd small patches of stunted Blechnum capense, Polystichum vestitum, Blechnum penna marina, and in rocky places Asplenium flabellifolium, Acaena Sanguisorbae vars., Celmisia spectabilis. At higher elevations occur Lycopodium fastigiatum and Hymenanthera dentata var. alpina. Along streams there is a more varied vegetation, including Hebe salicifolia var. communis, Aristotelia serrata, Gaya ribifolia, Griselinia littoralis, Olearia avicenniaefolia, and in damper spots Danthonia Cunninghamvi, Oxalis lactea, Anisotome aromatica var. incisa, Angelica montana, and other species, along with various ferns, among which Asplenium Trichomanes and A. Richardi are noteworthy.
(e.) Considerations Derived From The Study of The Forests.
From a study of all the examples of Nothofagus cliffortioides forest now existing it would appear probable that Nothofagus cliffortioides once clothed the sheltered sides of all the gullies. The greater rainfall in the area to the south of Little Mount Peel and in the deeper gullies has allowed a more mesophytic type of mixed forest to gain the ascendancy, restricting the beech to the more exposed knolls, and even threatening them with extinction there.
Supporting this view is the fact that various stages in the decadence of the beech forest on the knolls can be observed, one knoll at an elevation of c. 330 m. being now reduced to merely four or five beeches, among which is the ordinary mixed forest.
Some support is also given by the fact that the forest in almost equally sheltered places at Mount Somers, with a rainfall of only 857 mm., is almost entirely Nothofagus cliffortioides forest, while at Mount Hutt, with 1,048 mm., the forest is intermediate in character.
Such a view as to the character of the Nothofagus cliffortioides forest seems strongly supported by the arguments of Speight (l.c., 1911, p. 408). In this paper, Speight, in attempting to trace the climate of Canterbury since the glacial period, attaches great importance to the existence of former extensive forests in Canterbury. He says: “Apart from this coastal forest there were at the beginning of settlement considerable areas of standing bush, containing totara, black-pine, and white-pine, at Mount Peel, Geraldine, Waimate, and especially on Banks Peninsula, as well as in a few other localities in hilly places favoured by a good rainfall and a rich soil. At Mount Peel a considerable area still remains. These were in all probability remnants of a regional forest containing totara which covered extensive areas on the eastern slopes of the main range of the South Island.” He adds: “It is a remarkable fact, however, that the existing patches of bush occur in just those situations in which they might be expected to occur from ecological considerations had a slight desiccation of the climate come about.”
Using Speight's summary, we may make the following surmises as to the history of the forest at Mount Peel:—
The general sequence of events since the glaciation of the South Island in Pleistocene and post-Pleistocene times appears to have been the following:—
(1.) Glacial conditions, with probable steppe climate existing con temporaneously on the land to the east of the terminations of the
glaciers, a condition which probably continued for some time, as the glaciers were retreating. (The Rangitata glacier overrides the lower slopes of Mount Peel, which projects as a nunatak. With the retreat of the ice, fell-field is established, developing gradually into tussock-grassland on exposed slopes and Nothofagus forest on sheltered slopes.)
(2.) Moist climate over the tract to the east of the main range, during which the forests were established or were widely spread and the rivers built up their fans. (Mixed podocarp forest develops at Mount Peel as part of an extensive regional forest. Nothofagus driven from all but the exposed knolls and less sheltered slopes.)
(3.) Modified steppe conditions over the belt to the east of the main range. (Podocarp forest persists at Mount Peel, owing to especially favourable rainfall, while succumbing elsewhere. Relicts of Nothofagus forest enabled to retain their position, but with difficulty, and largely succumbing in the Peel Forest area.)
C. The Shrublands.
Shrublands of all degrees from very open communities to dense thickets and scrub occur in many parts of the area. Some bear a semi-primitive stamp, but the majority are more or less modified by fire or grazing, and many are reduced to fragments. Others, again, are indigenous-induced, and certain adventitious-induced associations are of importance. Although typical members of the shrub-communities described are frequent, there is sometimes a most bewildering admixture of various types. My treatment in this section is much condensed, as a full treatment would run to inordinate lengths. The following figures include all the members of indigenous communities, but omit many species that occur only as invaders or relics. Of the species that can be considered true shrubland members there are—Pteridophyta, 3 families, 10 genera, 14 species; monocotyledons, 5 families, 12 genera, 14 species; dicotyledons, 28 families, 49 genera 105 species. There are 18 species of Rubiaceae, 18 Compositae, 7 Scrophu-lariaceae. There are 13 families represented by one species each. Of the 133 species, 22 are abundant, 51 more or less common, 43 occasional or infrequent, 17 rather rare. The growth-forms include 4 small tuberousrooted herbs; 2 simple rosette plants; 20 tuft plants (4 ferns, 10 grass-like plants, 2 herbaceous, 3 semi-woody, 1 tuft tree); 5 trailing plants; 13 lianes (2 ferns, 3 scramblers, 5 twiners, 3 tendril-climbers); 19 creeping plants, including 2 turf-forming, 6 mat-forming, 10 sheet-forming; 70 bushy plants, including 6 leafless or scale-leaved shrubs, 20 spreading, 8 ball-like, 8 fastigiate, 22 divaricating, 4 depressed shrubs. There are 39 herbs, 8 semi-woody plants, 86 .woody plants. Hemi-parasites number 4.
(b.) The Associations.
1. River-terrace and Debris Shrubland.
(1.) Lowland.—The association, taken broadly, is dominated by Coprosma parviflora and Discaria toumatou, and may be modified, a relic of river-bed shrubland, or indigenous-induced. On concave slopes in the low-tussock grassland, exposed to much wind and insolation, and subject to burning, dry debris slopes develop colonies of Pteridium esculentum with various Rubi, and often a good deal of Paesia scaberula. Scattered among these are often Discaria toumaton, Coprosma parviflora, C. propinqua, Corokia Cotoneaster, Aristotelia fruticosa. Or a dense scrub of these divaricating
shrubs may be formed, with Rubus australis, R. cissoides, R. subpauperatus, Muehlenbeckia complexa, Parsonsia capsularis, Clematis marata, some or all scrambling over the mass. Sometimes Hymenanthera dentata var. alpina, as an upright divaricating shrub, is included. Below the densest scrub there is little else but Asplenium flabellifolium. The shrubland of riverterraces and stream-fans may be almost identical with the above, or contain other species—e.g., various divaricating coprosmas, Carmichaelia subulata, Notospartium torulosum, Melicope simplex, Coriaria sarmentosa, Leptospermum scoparium, L. ericoides, Fuchsia excorticata, Myrtus obcordata, Hebe salicifolia var. communis, Hebe leiophylla, × Hebe Kirkii, Olearia avicenniaefolia, Cassinia Vauvilliersii. Floor-plants are more numerous, and include Hypolepis Millefolium, Pellaea rotundifolia, Helichrysum filicaule.
(2.) Montane.—At an elevation of c. 600 m. occurs on coarse debris near streams an association with Olearia nummularifolia and Coprosma propinqua as dominants. There is also much Coprosma rugosa, Cassinia fulvida var. montana, stunted Dracophyllum longifolium, Coprosma parviflora, and sometimes Aciphylla Colensoi, Phormium Colensoi. The floor-plants are chiefly Hypolepis Millefolium, Polystichum vestitum.
(3.) Subalpine.—On debris slopes at c. 1,000 m. on small stabilized shingle-slips occurs a scrub dominated by C. parviflora and C. propinqua, with large open mats of C. ramulosa between. Hymenanthera dentata var. alpina, as a dense semi-cushion plant, and decumbent Coprosma serrulata, Dracophyllum uniflorum, Aristotelia fruticosa, Hebe buxifolia var. odora, Aciphylla Colensoi, Discaria toumatou are more or less common. The chief floor-plants are Hypolepis Millefolium, stunted Polystichum vestitum, Blechnum penna marina, Lycopodium fastigiatum, Acaena Sanguisorbae var. pusilla, Trisetum antarcticum. Clematis australis is occasional as a liane. Gaya ribifolia occurs infrequently.
2. Hebe buxifolia-Coprosma parviflora Scrub.
This occupies large areas on shaded slopes at c. 700–1,000 m., and is sometimes apparently a development from the subalpine scrub already described. It was formerly still more extensive, but has been broken up by fires. Besides the dominants, Coprosma propinqua, C. cuneata, Dracophyllum longifolium, D. uniflorum, Hebe Traversii?, Cassinia fulvida var. montana are more or less frequent. Hebe buxifolia increases greatly near streams, and here Aciphylla Colensoi and Coprosma serrulata are common, the latter not developing the creeping form with underground stems, but merely becoming decumbent. Notospartium torulosum occurs in some examples of the scrub, up to 950 m. altitude. At the higher elevations Hebe lycopodioides is often very common. Of the smaller plants the chief are Gaultheria depressa, Anisotome aromatica, Senecio bellidioides, Helichrysum bellidioides.
3. Leptospermum Shrubland.
(1.) Leptospermum Thicket after Grassland.—At Mount Peel the Leptospermum shrublands are mainly indigenous-induced after burning of forest or grassland, but there are not wanting examples that appear to be of primitive stamp. They occur in all stages from open shrubland to dense thicket. Here the association developing on burnt grassland is described. Both L. scoparium and L. ericoides invade burnt areas, usually the former dominating. The raoulias, Leucopogon Fraseri, Lycopodium fastigiatum, L. scariosum, that also invade burnt areas, are more or less suppressed by the rapid growth of the Leptospermum, as are Dracophyllum spp. and Gaultheria antipoda. The sunnier slopes favour Leptospermum, the shadier Dracophyllum. The chief other plants occurring in the later stages are
Botrychium australe, small Pteridium esculentum and Blechnum capense, Uncinia caespitosa, U. riparia, Microtis unifolia, Prasophyllum Colensoi, Lagenophora petiolata.
(2.) Leptospermum Swamp.—There are one or two examples of small swampy areas on grassland after felled forest with Leptospermum ericoides and L. scoparium dominant in varying proportions. Large mats of Nertera depressa surround the trunks, among which the water finds its way slowly downwards. On the mats are any of Blechnum penna marina, Epilobium nummularifolium, Forstera Bidwillii (slender and “drawn-up”), Luzula campestus vars., Thelymitra longifolia, Hydrocotyle asiatica, Uncinia riparia, Pratia angulata, Ranunculus hirtus, Anisotome aromatica var. incisa. Some of the following shrubs are usually present: Suttonia divaricata, Coprosma propinqua, Griselinia littoralis, Wintera colorata, Podocarpus dacrydioides (this often abundant but small). In shallow depressions Carex secta may be the chief plant below, and decadent Phormium tenax is common, the decadence partly due to the entry of cattle, which browse on the Phormium and Carex. Where the cover is not dense occur Scirpus inundatus, Ranunculus rivularis, Epilobium pallidiflorum; and with the conditions approximating to bog there is little below but sphagnum, with Blechnum penna marina and B. capense prominent on it.
(3.) Leptospermum scoparium-Exocarpus Bidwillii Association.—Broken rocky outcrops in low-tussock grassland at its higher limits often have an association dominated by a variety of L. scoparium and Exocarpus Bidwillii. The association may be open or closed. The Leptospermum is here a depressed shrub with dense, stout, spreading branches clothed towards the tips with thick broad leaves. Rather less abundant are the low, dense semi-cushions of Exocarpus Bidwillii. Other occasional shrubs are dwarfed Gaultheria antipoda, Dracophyllum longifolium, Hymenanthera dentata var. alpina, Hebe Allanii, trailing Suttonia nummularia. Where the association is not specially dense there are, as floor-plants, Lycopodium scariosum. L. fastigiatum, stunted Blechnum capense, Leucopo [ unclear: ] on Fraseri. Standing above the mass may be Metrosideros lucida, as a ball-like shrub, and stunted Podocarpus totara.
4. Dracophyllum Shrublands.
(1.) Dracophyllum longifolium Thicket.—Dracophyllum longifolium is an abundant plant in various associations up to c. 900 m., where it is replaced by D. uniflorum. It also frequently forms closed associations on rather steep, somewhat shaded slopes, and tends to reproduce itself after destruction by fire. Floor-plants are in greater number than in the scrub associations, more light penetrating to the ground, the chief species being Gaultheria depressa, Lycopodium fastigiatum, Anisotome aromatica, Senecio bellidioides, Leucopogon Fraseri, Blechnum capense, Poa Kirkii, Trisetum antarcticum. Some of the following shrubs are usually present : Hebe buxifolia, Coprosma parviflora, Cassinia fulvida var. montana, Gaultheria antipoda, G. rupestris, Pimelea sp., with Phormium Colensoi, Astelia Cockaynei, Aciphylla Colensoi.
(2.) Dracophyllum uniflorum Shrubland.—On rocky buttresses and running up steep spurs, thickets or more or less open shrublands dominated by Dracophyllum uniflorum are a well-marked feature high up among the tall-tussock grassland. D. Urvilleanum also occurs, along with Gaultheria rupestris, G. depressa, Coprosma ramulosa, C. parviflora, C. serrulata, all in small amounts. The commonest herbs are Celmisia spectabilis, Anisotome aromatica, Seneco bellidioides, Ranunculus Monroi var. dentatus, Forstera Bidwillii, and Microlaena Colensoi.
(3.) Dracophyllum rosmarinifolium Dwarf Shrubland.—On the exposed slopes of Middle Peel an interesting dwarf shrubland occurs in more or less extensive patches amongst the fell-field and intergrading with it. The Dracophyllum is dominant, and associated with it are Pentachondra pumila, Phyllachne Colensoi, Drapetes Dieffenbachii, Gaultheria depressa, Raoulia grandiflora, Celmisia laricifolia, Lycopodium fastigiatum.
5. Cassinia Open Shrubland.
As noted above, Cassinia fulvida var. montana is a member, sometimes an abundant one, of various shrubland associations. In the Blechnum capense-Phormium Colensoi belt this Cassinia and C. Vauvilliersii frequently occur in marked amounts, forming an open shrubland. The association is indigenous-induced after burning. Burning, though only slightly affecting the Blechnum capense, sufficiently opens the association to allow of the free-seeding Cassinia to increase greatly, the seedling being tolerant of considerable shade. The remaining plants are those of the original association described later.
6. Scrub of the Upper Margins of the Rain Forest.
(1.) General.—The forest at its upper margin merges either into tall-tussock grassland by way of a narrow scrubby belt, or into one of the shrub associations above described, but there is no broad marginal belt. In the gullies the scrub consists mainly of dwarfed Griselinia littoralis, Nothopanax Colensoi, N. arboreum, Olearia arborescens, O. avicenniaefolia, Senecio elaeagnifolius, Nothopanax simplex, Fuchsia ercorticata, Hebe salicifolia var. communis. Rubus australis scrambling over these completes the scrub. On the ridges the following are prominent: Leptospermum ericoides, Suttonia australis, Senecio elaeagnifolius, Nothopanax simplex, Dracophyllum longifolium, Gaultheria antipoda.
(2.) Senecio elaeagnifolius Dwarf Forest.—On certain broad ridges the mixed forest is succeeded by a rather extensive association in which Senecio elaeagnifolius is dominant, the remaining shrubs being quite few in numbers. The Senecio is here a large shrub, up to 4 m. high, much branched from the base, the branches stout, wide-spreading, naked, with loose papery bark. Above, the branches divide several times at wide angles, the branchlets ending in rosettes of closely-placed large coriaceous leaves of oval form, dark-green above, with pale-buff appressed tomentum beneath. The shrubs are close together and form a continuous canopy, beneath which the vegetation is sparse. Here and there are slender sparingly-branched Leptospermum ericoides, Nothopanax simplex, N. Colensoi, Coprosma linarii-folia, Griselinia littoralis. Smaller still are odd bushes of Coprosma rham-noides and Gaultheria antipoda, open in habit. The floor-plants are small in size and scattered—Blechnum capense, Lycopodium volubile, L. Billardieri, Polypodium diversifolium. Seen from a vantage-point above during the flowering season this association is beautiful with its masses of golden flower-heads completely hiding the foliage.
Cockayne, L, 1917. Notes on New Zealand Floristic Botany, including Descriptions of New Species. &c. : No. 2. Trans. N.Z. Inst., vol. 49, p. 56.
—, L, 1919. New Zealand Plants and their Story. 2nd ed. Wellington.
—, L, 1921. Die Vegetation der Erde vol. 14, Vegetation of New Zealand. Leipzig.
Speight, R., 1911. The Post-glacial Climate of Canterbury. Trans. N.Z. Inst., vol. 43, p. 408.
Speight, R., L. Cockayne, and R. M. Laing, 1911. The Mount Arrowsmith District: a Study in Physiography and Plant Ecology. Trans. N.Z. Inst., vol. 43, p. 315.