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Chapter I.
Preliminary Remarks.

It is not generally understood that the New Zealand Botanical Region possesses certain fundamental characteristics absent elsewhere. In the first place, the two main islands are together far and away greater in area than other masses of land equally remote from the nearest continent. Nor is this extreme isolation a thing of to-day but it dates far back into geological time, so far indeed that a flora has developed — considering only the angio-sperms — with four-fifths of its species endemic, while many bear virtually no relationship to others elsewhere. The flora, too, falls naturally into the few clear-cut elements dealt with in Part IV, Chapter II, so the phytogeographer generally need be in little doubt regarding the supposed origins and relationships of the species with which he has to deal.

Perhaps even more striking than the systematic position of the plants is their distributional ecology, sociology and life-forms, all three bound up, in large measure, with the peculiar climatic conditions and geomorphological features of the islands, though neither the effect of the complete isolation of the region nor its geological history must be overlooked. Can any other part of the globe equal in area boast a vegetation which has to cope with such a variety of circumstances? Consider the rainfall of more than 6000 mm. in some parts and less then 350 mm. in others, the violent rainless hot winds and the piercing subantarctic gales with a cold downpour, the warm sheltered frostless valleys, the alpine heights with perpetual snowfields and huge glaciers descending to extremely low altitudes, or the lesser heights where snow lies all the winter and far into the summer. Then there are the conditions supporting luxuriant subtropical rain-forest in many parts and subantarctic Nothofagus forest in others; there is the vegetation which can tolerate the neighbourhood of boiling springs and fumaroles, or soils containing an excess of magnesia or of salt; there are enormous unstable stonydebris fields in the drier mountains and the scoria slopes of the volcanoes, page 2both with their highly-specialized plant-life; finally there is the gradual latitudinal change in the flora with species suddenly giving out and others coming in.

Perhaps the most striking feature of New Zealand phytogeography, dealt with more fully further on, is the vegetation having gained its structure unexposed to the attacks of grazing and browsing animals, the moa (Dinornis) excepted. Nor did the aborigines cause any change except to a comparatively limited extent in the neighbourhood of their villages. The absence of this grazing-mammal factor stands out clearly in the light of what has happened since the white man occupied the land. Besides the main islands there are others adjacent thereto as also isolated groups far away northwards, southwards and eastwards. These far-distant groups of quite small islands have each their special floras containing not only a true New Zealand element but marked by a high degree of endemism. Nor is this all, their vegetation is of a more or less peculiar character and the most southerly of the southern groups — the Macquarie Islands —, though only as far distant from the equator as north Yorkshire, possesses a flora of only 34 species of vascular plants!

The New Zealand flora, existing as it does under such diverse conditions, obviously must be made up of many life-forms, yet, in harmony with the mildness "of the climate, there are certain wide-spread, general features. Thus, for the most part, the plants are woody or semi-woody; they can endure no high degree of frost, in fact many (probably nearly all) are close to their frost-resisting capacity; a large percentage are evergreen; ferns are extremely abundant; bryophytes, often of great size, are a most frequent feature. Thus there is a strong hygrophytic element which is largely of palaeotropic origin. On the other hand, there are many life-forms more or less restricted to definite habitats, many of which forms are so strongly xerophyitic that, as Diels was the first to point out, they do not seem suited to their present-day conditions — a supposition strongly supported by the fact that these xerophytes grow in company with typical mesophytes. Then there is that peculiar biological group consisting of plants which persist in a juvenile form distinct from that of the adult for many years — in some cases 50 years and more — and many are xerophytes at one stage and mesophytes at another. Finally, it must be noted that wild hybrids are extremely common and that such do not consist of one or two individuals but frequently of great polymorphic swarms.

At the present time the plant-covering of New Zealand differs greatly from what it was in the comparatively recent pre-European days. Then, as already noted, almost all the vegetation was primeval. But now by far the greater part of the lowland belt bears a stamp of a European character. All the same, thanks to the rugged, mountainous nature of much of the land, and to the fact that many scenic reserves and large national parks have page 3been established, there are still numerous areas — some of great extent — which are not only virgin, or nearly so, but which represent almost all the primitive types of vegetation. Nevertheless, these splendid remnants of the primeval world bid fair, except in inaccessible situations, to be seriously modified. This deplorable state of affairs is the result not so much of destruction for the rightful purposes of settlement, but rather for there having been turned loose in the forests and on the pastoral lands animals inimical to vegetation (deer of various kinds, rabbits) simply for purposes of so-called "sport". The deer, assisted in some places by cattle which have become wild, are doing excessive damage over wide areas to forest undergrowth and frequently - forbidding all natural regeneration. Some of the virgin plant communities described in the first edition of this work have been altered greatly or even destroyed. Vegetation, which came into being in the absence of grazing and browsing mammals, is ill-equipped to withstand their onslaught. Ecologically, it is all-important to study what happens, but the effect is heart-rending.

Far behind the grazing animal as a modifying and destroying element are the introduced plants. These in their hundreds of species and vast numbers of individuals have spread through the length and breadth of the region; but, when they come in contact with the truly virgin vegetation, they — one and all — come to a halt. Nevertheless, once there is an open place, especially where the soil has been disturbed, exotic species more or less readily gain a footing. So, too, indigenous species may contend for the mastery in the new habitats. Thus there is every transition from primitive to artificial vegetation and on this the following primary classification used in this book depends.

The Vegetation is made up of plant-communities which, if actually virgin are (1) Primitive, but if not changed so fundamentally as to have lost their primeval stamp they are (2) Modified, while all other communities which differ greatly from the primitive and have been made directly or indirectly by man's action are called (3) Induced. Induced vegetation consists of the three following classes: (1) Indigenous-Induced when the dominant member or members are indigenous species which have come into the community by man's indirect action, e. g. Pteridium heath, Danthonia grassland; (2) Exotic-induced when the dominant member or members are exotic species which have come into the community by man's indirect action, e. g. Ulex thicket, Plantago Coronopus salt-meadow; and (3) Artificial-induced where the community has been directly made by man by ploughing and sowing or other means, e. g. Eucalyptus plantation, wheat field. A fairly detailed account of these non-primitive communities is given in Part III, Chapter II, but here they are defined since in Part II not only the actual primitive communities are dealt with but also those which are slightly modified. This treatment differs from that of the first edition since it not only page 4attempts to depict the plant-covering of primitive New Zealand but it seeks to show more clearly the early stages in the development of the new vegetation by keeping the descriptions of both classes side by side. An account of this evolution of a vegetation new to the globe seems particularly important since there can be very little really primitive vegetation in Europe. But in New Zealand, there can be estimated to some extent the reaction of the primitive vegetation to the new factors — grazing and browsing animals and exotic plants, the latter mostly of life-forms absent in the New Zealand flora.

The foregoing classification is not nearly so simple to put into practice as it seems. This may best be seen from a few examples. Who can say, for instance, how far much of the Pteridium heath is truly primitive? Yet who in the pre-ecological days of New Zealand would have questioned its apparently virgin character. So, too, with certain areas of tussock-grassland the question arises, have they replaced forest? No association bears the stamp of one truly primitive more than that of Jack's Pass near Hanmer (NE.), made up almost entirely of mountain plants; but the remains of burnt trees and small patches of forest show that it is altogether an indigenous-induced community and not a primitive one slightly modified., Near Clinton (SO.) there is a remnant of forest undergrowth of a primitive stamp consisting of Fuchsia excorticata, yet it owes its existence to the other trees having been removed for firewood, the Fuchsia, thanks to its bad reputation for burning, having been left. In the Urewera Country (EC.) there are considerable stands of the last-mentioned species, but such are quite primitive and represent a stage of forest development or retrogression.

In dealing with the groups of vegetation in Part II, it has seemed advisable to write sometimes in the present and sometimes in the past tense, using the former when the community has been studied recently and the latter when this took place some years ago, and there is reason to believe that since then it has been more or less modified or even destroyed. As an example, a certain piece of forest of the Chatham Islands visited by me in 1901 had stock turned into it soon after my visit, so it is now greatly altered.

In Part II, when dealing whith the communities, the associations are arranged rather into groups of such than into definite associations, for the latter, like the contents of species, are generally an expression of their describer's opinion rather than distinct entities. To arrange the entire vegetation of New Zealand according to the natural small groups of which it consists is a task of great magnitude requiring many workers, working according to a definite system.

The primary aim of this book is to present an accurate picture of the whole plant-covering of the New Zealand Botanical Region. In order to do this some uniform system of classification is necessary, but its nature seems page 5to me to be a matter of comparatively small importance, the essential points being that it be simple, readily understood, and used as consistently as the complexity of the vegetation will permit. Such classification is here based, not on habitat or succession, but on the actual combinations of the plants themselves — though their dynamic relations are frequently discussed. Thus forest is a distinct community made up of trees growing closely, but it flourishes on almost every kind of soil no matter what the chemical and physical constitution may be and it is the climax of different successions originating on habitats distinct from one another, e. g. swamp, bog, unstable dune, dune-hollow, deep pumice, stony river-bed, glacial deposits and soil made from the weathering of-most classes of rock.

Habitat — using this term in a restricted sense without reference to climate — is, however, by no means ignored in my classification. On the contrary, in order to obtain a clear picture of the vegetation, as well as for Convenience of study, habitats of a specially distinct character are made use of for the primary name of the vegetation, or groups of communities, which constitute their covering, notwithstanding these groups may belong to different formations. Thus it will be seen that dune, rock, stony-debris and other striking habitats are used as descriptive titles for the classes of vegetation which they support, though the latter is to be distinguished in the long run by its ecological and floristic characters.

Having arranged the vegetation into its primary divisions according to its indigenous or exotic composition, there comes the much-debated question of its ecological nomenclature. Here Warming's system of 1909 is, in the main, followed. The communities, are divided into the plant-formation, plant-association, subassociation and plant-colony, and there are also to be distinguished successions and temporary associations; these terms may be respectively defined or explained as follows:

The plant-formation is an assemblage of plants of definite life-forms, one form or more than one — frequently many — being represented, and for the formation as a whole there is a representative flora. Thus, though primarily an ecological conception, it is also floristic and the latter character is sometimes of considerable importance. Particular plant-formations need not be restricted to a particular phytogeographic region, they may be world-wide, and such may be disignated major formations and their regional divisions minor formations, but for convenience the word "minor" is omitted in this book. The plant-association is a portion of a plant-formation distinguished by a definite floristic composition. A subassociation is a community within an association distinguished by its slightly different floristic composition, especially the dominance of some species other than that considered dominant for the association as a whole. Thus the taraire and the kauri subassociations occur in the kauri-broad-leaved tree association. The colony is a more or less pure group of one or more species page 6in the association or subassociation, as a tree-fern colony in a forest association or a Ranunculus Lyallii colony in a herb-field association. Dominance, mentioned above, is not a matter of the largest number of any species present, but of that species which physiognomically dominates, e. g. in indigenous-induced steppe the commonest plant is the tiny Poa maniototo, but the flat cushions of Raoulia lutescens dominate (Fig. 59).

All associations are in process of change, but where there is apparent stability the community may be called a climax association, and a temporary association where more or less rapid change is in progress. Succession depends upon the alteration brought about in its habitat by the association thereon — both of plants and animals — which leads eventually to a new association being established, as where the Raoulia association of stable stony river-bed, through colonization of the raoulia mats or cushions by other plants, adds humus to the substratum and so paves the way for Festuca tussock-grassland. This particular kind of change is biological succession. Such may also come about through the "struggle" &c. of plant with plant, as when the epiphytic Metrosideros robusta kills its host, Dacrydium cupressinum, and its life-form, now that of a tree, replaces its former host, or where the Metrosideros itself is killed by the weight of epiphytic Asteliae its life-form encourages. Also the presence of gracing animals, or a plant-disease, readily brings about succession. Geomorphological change leads to a spurious succession in which plants may play no part, and a new habitat arises ready for a new association or it may be a new formation. An interesting example of the latter is where the wind transforms a dune into a sand-hollow or sand-plain, the original sandgrass association having nothing to do with the new vegetation of the latter. Gradual geomorphological change, however, may go hand in hand with biological action as in the case of river-bed, cited above, where, but for the raising of the bed above the stream's reach there would be no succession.

Should succession lead to the incoming of life-forms different from those of the preceding association, such a succession is not here considered part of the original formation, though the habitat may not be greatly changed; thus the vegetation of unstable dunes belongs to a different formation from that of the subsequent shrubland and this, again, from that of the final dune-forest.

Before closing this chapter a brief explanation must be given of the taxonomic terms and conceptions used throughout this book which are those put forth by H. H. Allan and myself in recent publications. The underlying conceptions axe, (1) that the term "species" can quite well be defined, (2) that the units on which, it is based are virtually invariable, and (3) that the content of these is not a matter of opinion but of fact.

The terms used by Allan and myself and their meaning are set forth page 7in the following statement taken from one of our joint papers (1926: 12), the only alteration being the bold type. "As our fundamental field-unit we here take with Lotsy¹ (1916, p. 27), the jordanon, which may be defined as "a group of externally alike individuals which breed true when bred among themselves." A jordanon that is not closely related to any other jordanon is easily recognizable in the field as an "invariable species," and such we term a simple species, e. g. Hebe cupressoides. More often groups of closely-related jordanons are met with, and such groups we term compound species, as the more familiar terms "aggregate species and collective species" have now a wider and vaguer connotation. Jordanons that are sufficiently distinct to allow of effective diagnosis we call varieties. It should be emphasized that as so defined the variety is of as much importance as the species. Compound species to which in the past taxonomy has attached "intermediates" we term linneons. Lotsy (loc. cit, p. 27) uses the term linneon "to replace the species in the Linnean sense, and to designate a group of individuals which resemble one another more than they do any other individuals." As modified by us the term linneon is used to include not only groups of allied jordanons but of the hybrids between them as well. In its widest sense it includes two or more closely related species, their jordanons, and hybrids of all categories. This is what in practice the so-called "Linnean species" have become, coupled, not seldom, with what we later define as "epharmones." The intermediates we consider to be hybrids. Unfixed forms, due to habitat conditions, which change when these are sufficiently modified we call epharmones. Of course, strictly speaking, the "normal form" is as much an epharmone as any other, and sometimes it would be difficult to say which form should be classed as the "normal" one, but in practice this seldom occasions any difficulty…… We use the term form where it is convenient to waive the exact status of an individual or group, or where that is unknown. With Bailey (1924, p. 25) we use the term cultigen for a form of unknown origin found only in cultivation."

Finally, it may be pointed out that the account in this book of the vegetation is generally based upon my personal examination — frequently too rapid — of such areas as I have been able to visit. Such are in all the botanical districts, except the Kermadec and the Macquarie, and as they usually represent various parts of each district (sometimes many parts), they may be taken as giving a fair idea of the vegetation in general. A few descriptions are compiled from the notes, generously given to me, of other ecologists, and such matter from earlier writers as appears of moment has been embodied, but in the last two cases the sources are always indicated. As for the material from which the descriptions of the communities have been drawn up, it consists almost entirely of notes including photographs taken by me in the field.