Art. XLIV.—On the Disappearance of the New Zealand Bush.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 29, 1896, Page 490

Art. XLIV.—On the Disappearance of the New Zealand Bush. By the Rev. P. Walsh. [Read before the Auckland Institute, 19th July, 1896.] No one who has lived any length of time in New Zealand can have failed to observe the rapid disappearance of the natural bush, and even the casual visitor discerns the evidence of it in the appearance of the country, though he may not be able to appreciate the rate at which it is going on. Wherever we go—along the coast or inland, on plain or mountain—we find in the gaunt skeletons which disfigure the open, and in the brown and withered margin of the standing forest, unmistakable signs of destruction and decay. It is the purpose of the present paper to point out some of the principal causes which have combined to produce this state of things, my information on the subject being based on observations made during a residence of thirty years in various parts of the colony. There can be little doubt that at some distant period the greater part, if not the whole, of New Zealand was covered with forest. The evidence of this is found not only in the roots embedded in situ in the open ground and in the remains of forest buried beneath the soil, but also in the surface corrugations caused by the falling-over of trees of which no organic traces at present remain. Of the causes of the disappearance some have been in operation during the long ages which preceded any human occupation of the country. In the regions of volcanic action there is no doubt that extensive areas of bush were destroyed at various periods by the lava-flows and by the hot stones ejected from the numerous craters, while still larger portions were buried under showers of ash and pumice and volcanic mud. In the northern gumfields, which cover a wide extent of country, whose present vegetation is mostly confined to a

scanty growth of tea-tree, the digging operations frequently reveal successive surfaces strewed with the remains of the primeval forest, while in other parts the same thing is often brought to light by mining and engineering works, as well as by landslips and river erosions. Wherever, in fact, excavation is conducted in alluvial or volcanic country it is usual to find the remains of a former vegetation, generally of large growth and frequently in sound condition. It is probable that, had no other causes intervened beyond those already named, the country might have gradually become reafforested. So much, indeed, is indicated by the successive beds of timber that have been found—sometimes as many as two or three—one above the other. The destruction, though severe and often widespread, occurred at intervals; and there would generally be ample time for nature to reassert herself. But with the advent of a population, even though comparatively small and widely scattered, other conditions were introduced which made the work of destruction much more rapid and complete. The Maoris were a busy people, and, if not employed about the precincts of the kainga, they were generally roving the country on their hunting and fishing expeditions, visiting from settlement to settlement, or engaged in warlike expeditions. The fire-stick formed an important part of their travelling outfit, and was constantly in requisition to clear away the dense growth offern or tea-tree which impeded their movements. The fires so kindled would sweep over the country during the dry edge of the bush, and gradually extending the area of open land. Such fires were noticed by Tasman as he sailed along the western coast two hundred and fifty years ago, and they are still to be seen in all parts of the country. Much of the destruction of the bush is therefore to be accounted for both by natural causes and by several centuries of Maori occupation. But with the progress of European settlement a host of new conditions have been added, which, in conjunction with those already existing, have greatly precipitated matters. The Maori settlements were confined to certain localities where the conditions of soil, climate, &c., were peculiarly favourable, and, though comparatively numerous, they formed in the aggregate but a small fraction of the total area of the country. For want of proper tools, moreover, their bush-clearings were necessarily confined to the margin of the forest, where advantage would be taken of the dead timber, and were, in fact, little more than a “clean-up” after the former fires. But since the axe and saw have come into operation the living bush has been attacked throughout the length and breadth of the land, and not only is an increasing area annually deforested for farming purposes, but the bush is

gutted in all directions by timber-workings and road- and telegraph lines. Over these the fires find their way in successive dry seasons, ever penetrating more deeply into the standing forest, until sooner or later in many places the whole country-side is swept, and only a few isolated patches in some of the damper situations remain amid the general desolation. It used to be said that the New Zealand bush, unlike that of Australia, would not burn standing. This was true to a certain extent, but the comparison no longer holds good under the present altered conditions, and the chief difference now is that while the Australian bush recovers more or less from the burn that of New Zealand perishes, never to be restored. In its virgin state the New Zealand bush, with the exception perhaps of the kauri forest, was comparatively impervious to fire. The general bush was dense and dark. The tops of the trees formed a close canopy overhead, and the ground was covered with a succulent growth of ferns, mosses, and seedling plants, which protected the roots, and maintained everything in a moist condition; so that, with the exception of a small portion along the margin, killed by former fires and exposed to the action of the sun and wind, the whole bush was practically safe. But all this is now changed. As the cattle find their way in, the thick undergrowth is eaten or trodden down never to reappear. The network of superficial roots is barked and torn, and the soil, poached by the constant trampling of hoofs, is hardened in summer to the consistency of concrete. The consequence is that the larger trees, deprived of their natural protection, and unable to obtain a proper supply of sap, soon grow thin and open at the top, and many of the more delicate species die out altogether. The sun and wind find entrance, and the fronds of the nikau and the fern-tree, which flourished in the crypt-like shade, shorten and shrivel up. The ground is covered with fallen leaves. The old rotten logs, which represent the natural decay of centuries, are dried to powder, and before many years are past the whole bush, which originally retained its moisture like a sponge through the driest season, is ready to burn to extermination. It is not to be supposed that the influence of the cattle is confined to the vicinity of the settlements, though it is felt here in a greatly intensified degree. At the present time there is practically no part of the bush—in the North Island at least—that is not overrun, more or less, and upon which they have not already left their mark, the tame stock browsing around the farms and townships, and wild mobs running at large among the back ranges and gullies. For years past this has been the case in the extensive mountainous districts extending along the West Coast from Whangape to the Manukau Heads,

and covered by an almost unbroken forest for a distance of a hundred and fifty miles. Here, far removed from any homestead, and in places as yet uninvaded by the bushman or the road-surveyor, the presence of the animals is already plainly indicated by the shrinking tops of the rata and the, towai, and in the gradual extinction of the tawa and others of the more delicate forms of vegetation. The same thing is going on more or less all over the country, though, of course, it is not so conspicuous in the more newly-settled districts, and it is hard to say whether any portion of the forest between the North Gape and Stewart Island will be permanently secure. The change which has gradually come over the bush in all the older settlements is often noticed by those who have an opportunity of making the comparison. In the early days, before the cattle had time to make much impression, a great deal more care than is at present required was taken in order to secure a good burn, and the fire, no matter how fierce, did not generally extend far beyond the margin of the clearing. Nowadays any kind of work is considered sufficient. Instead of the laborious lopping and under-scrubbing, formerly considered indispensable, “crush-and-smother” is the order of the day, and the chief difficulty is to keep the fire from travelling beyond all control. The effect of the combination of destructive elements may be seen on a wide scale in any of the larger bush-settlements. On the Akaroa Peninsula, for instance, the forest has almost entirely disappeared within a comparatively few years, while the Forty-mile Bush, in Taranaki, and the Seventy-mile Bush, on the East Coast, will shortly exist only in name and in the recollection of the early settlers. As may be inferred from the foregoing, all bush which has been invaded by cattle is liable to be swept by fires, and is sooner or later exterminated. The rate of destruction varies, however, a good deal with the conditions of situation, soil, and character of vegetation. Generally speaking, it is most quickly accomplished on high, airy situations, where the growth is usually more light and open, and especially on stiff clay lands, where it often takes place with surprising rapidity. All these conditions are united in the case of the kauri forest, which, in addition, possesses peculiar elements, rendering it liable to rapid extinction. As this class of bush is at once the most beautiful and economically valuable, a detailed account of its destruction will not be out of place. The bushmen say that the kauri attracts the fire, and the statement is hardly an exaggeration. Wherever the kauri-trees grow, which they generally do in clumps scattered through the mixed bush, the ground is covered with a thick

layer of humus (pukahu), composed of vegetable fibre intermingled with fallen leaves, particles of gum, and scales from the resinous bark, the latter helping to form a solid bank, sometimes several feet in height, round the base of the trees. This, from the nature of its composition, is of a most in-flammable character, and once ignited will burn for weeks together, smouldering underneath even when wetted on the surface, and “piping up” with every drying breeze. Every tree, of whatever sort, reached by the fire is killed. The tufts of the toe-kiwi—the “cutting-grass” of the bushmen—which are a feature of the kauri bush, are set in a blaze; and, as the flames flare up the loose bark of the ratas and the trunks of the more gummy specimens of the kauri, the masses of puwharawhara (Asteliads) which encumber the branches are ignited, and fall in fiery showers to form fresh centres of combustion. The open character of the kauri bush, moreover, and the comparative absence of the succulent growth before mentioned as a general characteristic of the New Zealand forest, both tend to facilitate the progress of the fire, which, when once properly started, will continue to burn until thoroughly drenched by the heavy autumnal rains, the most laborious efforts at extinction generally proving unavailing. No description, however verbally accurate, will convey an idea of the scene of desolation presented by a kauri bush after the fire has gone through it. The ground is covered with a deep bed of ashes strewn with fallen branches and with the wreck of the smaller trees. Here and there a giant rata, its buttressed roots burnt through, has crashed down through everything, and lies with broken limbs and a smoky cavern in its hollowing trunk. The stately totaras, whose fibrous bark conducted, the flames to the tops, when for a moment they became as so many blazing torches, now stand grim and black. The waving tufts of the toe-kiwi are represented by a coil of snake-like roots. The fern-tree's feathery fronds and the glossy curving spikes of the neinei hang shrivelled and limp, while the netted ropes of the mangemange are gone altogether—vanished in a puff of flame. All the ferns and mosses, the orchids and climbing plants, all the light and graceful undergrowth indigenous to the kauri bush, which made the place a fairy paradise, are charred and dead. The kauris alone seem to have escaped the general fate. With the exception of the more gummy specimens, and those which were exposed to the hottest part of the fire, they still stand proudly erect, the bark retaining its peculiar silvery sheen, and the head its noble crown of leaves. But this hopeful appearance is only deceptive. The slightest scorching about the root is sufficient to kill a kauri-tree, and though the leaves may remain green for months, as they frequently

do, once it has felt the heat of the fire its life is a thing of the past. The first fire in a kauri bush may go on for months, and unless a strong wind is blowing, in exceptionally dry weather, its progress is generally slow, and often is scarcely perceptible. But when the second fire passes over it the destruction, only begun before, is quickly completed. By two or three years' time the ground is covered with fallen leaves and twigs and fragments of gum, together with the wreck of the bark, split up and flaked off in thick broad sheets. The sapwood, pierced by the worm and rotted by the action of the weather, is in a condition of tinder. A rank growth of ferns, rushes, and coarse grasses, nourished by the ash, has quickly taken possesion of the soil, and helps to carry the fire along. The fire once kindled spreads with frightful rapidity. A roaring torrent sweeps through the bush; every tree becomes a blazing torch, and the whole ground is covered with a sheet of billowy flame; and in an incredibly short time all that is left are a few smoking trunks and fallen logs. But the fire has not yet quite done with the kauri bush. By degrees the fern gives place to the tea-tree, and, as this is burnt by successive fires, before many years are past scarcely a charred stump remains to mark the site of one of the grandest triumphs of nature in the vegetable kingdom. Prevention And Restoration. The question may naturally be asked, Are there no means of prevention and restoration ? In regard to prevention the answer has already been anticipated. All that is necessary is to hermetically seal the bush against the incursion of stock and make adequate provision against fires. But the remedy, though simple enough, is not always easy of application. It is obvious that no such general measure could be adopted in the case of the bush at large, especially in the neighbourhood of settlement, where all unoccupied land is used as a common run. However much we may lament it, the great bulk of the bush will have to take its chance; and, in regard to detached portions of small area, such as a man might hope to preserve on his farm, there are several difficulties to contend with which generally render an attempt in this direction fruitless. Not only are they in continual danger from accidental fires, but from want of the shelter of the surrounding bush, of which they originally formed a portion, they die back at the edges, and sooner or later resolve themselves into clumps of scrubby survivals of some of the more hardy varieties. It is possible that, by planting some quick-growing trees, such as the Australian wattles, round the portions intended to be preserved, both a

check to the advance of the fire and the required shelter would he provided. At any rate, the experiment is well worth, trying. In the case of reserves chosen with due regard to topographical and climatic conditions the case is more hopeful. On some of our mountainous promontories and wooded islands there should be no difficulty, at a slight expense for fencing and supervision, in preserving for posterity large areas of forest of unsurpassed scenic beauty and of great economic value. Restoration might also be hopefully attempted under similar conditions. Experiments in our parks and gardens show that most, if not all, of the native trees will grow freely under cultivation. But such an artificial procedure need not generally be taken. Nature makes a brave effort to reclothe the hills and gullies of New Zealand in her verdant mantle, and if let alone would bring her work to completion. Under favourable circumstances seedling trees soon make their appearance, and if protected from injury would in due time attain to maturity. Of course, anything like a real restoration of the original bush is out of the question, but the “second growth” has a beauty of its own which is by no means to be despised. This natural attempt at reafforesting may be seen on a large scale in many parts of the colony, especially in elevated and damp situations, such as the steep hills and gullies of the Northern Peninsula, the ranges about Coro-mandel and Mercury Bay, and the upland portions of the Nelson Province; and it is interesting to notice that everywhere the trees which are characteristic of the locality are not long in making their appearance. Nothing, however, either in the way of prevention or restoration can be hoped for without a radical change in public opinion, and a general improvement in public taste. So long as the farmer persists in cutting down the native growth that is at once an ornament to his property and a shelter to his stock, in order to make room for a row of Cupressus macrocarpa or Pinus insignis, or so long as the gum-digger and bush-larrikin are allowed to put a match into anything that will burn, there is not much hope for either prevention or restoration. Year by year the destruction will continue, and the rate of the disappearance of the New Zealand bush will be proportionately accelerated as population increases and settlement spreads abroad.