Art. XXXIX.—On the Future of the New Zealand Bush.
[Read before the Auckland Institute, 15th August, 1898.]
In a paper* read before the Auckland Institute two years ago I drew attention to the extensive and rapid disappearance of the native bush in many parts of the country, and endeavoured to trace the principal agents which combine in the work of destruction. It may be interesting to follow the subject a further stage, and attempt, by the observation of present facts, to forecast the future condition of the forest when something like a balance shall have supervened between the destructive agents on the one hand and the resilient power of nature on the other.
In order to present the matter clearly, it will be well to recapitulate the argument of the former paper.
The two principal destructive agents, besides the axe of the bushman, are fires and cattle, to which should be added the wild pig, or “Captain Cooker,” as this animal does his full share. Any of these acting alone is sufficient to do a good deal of damage, but when they all act in conjunction, as they generally do, the destruction is greatly accelerated and intensified.
The whole of the forest below a moderate altitude throughout both Islands is more or less an open cattle- and pig-run, in which, by the browsing, trampling, and rooting of the animals, the undergrowth is gradually destroyed, the surface roots lacerated, and the soil trodden into mud, which in summer hardens almost into a bed of concrete. The consequence is that the larger trees, deprived of their accustomed nourishment and protection, grow thin and open at the top; the ground is covered with fallen leaves; the debris of centuries, now exposed to the sun and winds, is dried to tinder; and the whole place is ready to be swept by fire, which sooner or later inevitably happens.
In thickly settled districts, and in those where timber-getting is carried on, the destruction is most rapid and complete, as every clearing, timber-working, and road-line forms
[Footnote] * Trans. N.Z. Inst., 1896, Art., xliv., “On the Disappearance of the New Zealand Bush.”
a starting-point for the fires, which spread into and kill some portion of the adjacent standing bush. And, as wherever the fire has once passed it will pass again while there is anything left to burn, before very long, in districts where clearings are frequent, the whole bush is consumed, with the exception, perhaps, of that which stands in the lower and damper situations, or which, from the conformation of the country, is protected from the sweep of the flames. In this way, in a comparatively few years, immense areas of magnificent forest have been entirely destroyed in many of the more settled districts, while in others the work is going on more or less rapidly and completely, according to the nature of the bush and the climatic and other conditions.
3. Sow far will the Destruction extend, &c. ?
Now, the question is, How far will this destruction extend, and what will be the ultimate condition of the portion that escapes? It may be broadly stated: (I) That below a certain altitude, varying according to locality, climate, and aspect, wherever the soil is fairly fertile, the bush once removed will never reappear; (2) that in elevated and barren country, especially in cold and moist situations, the bush has a fair prospect of remaining practically in its virgin condition; (3) while between the two the battle will be fought with varying success, and that, though considerable portions will escape extinction, they will undergo a gradual but very complete alteration in character and appearance. Each of these propositions may be considered in detail:—
(1.) In open fertile situations, under favourable climatic conditions, all burnt land is soon covered with a thick “sole” of grass, in which even were a seedling tree to spring up it would be immediately eaten or trodden down. In new clearings in this class of country a few trees will probably survive for a time in the imperfectly burnt patches, or a light second growth come up amongst the stumps and logs in spots beyond the reach of cattle. But unless permanently protected by some inequality of the ground, as in the case of steep ravines, river-banks, &c., they will gradually disappear as the animals push their way through the rotting timber, and as the fire once more overruns the place, which it is sure to do so long as any considerable portion of the dead stuff remains. This is what may be seen in all its stages on any bush farm, and is taking place on a large scale throughout the districts of Taranaki, Manawatu, parts of the Wellington and Nelson Provinces, and the Akaroa Peninsula, where practically the native bush is a thing of the past, and where in a few years, when the stumps and logs have disappeared, the country will be as clear and open as the Napier or Canterbury Plains.
(2.) In high, mountainous country, especially in regions where the climate for the greater part of the year is cold and wet, the floor of the bush, instead of being covered with an esculent growth of underwood, is chiefly coated with a layer of damp moss; so that there is not much to attract the wandering beasts or to feed a fire even in the driest seasons. In such country the conditions of soil and climate preclude the possibility of settlement, while the trees are generally too small or too difficult of access to be of much economic value from the timber-getter's point of view. This favourable state of things obtains in all high altitudes, but especially in the mountain districts of the south and west; and here it is satisfactory to think that Nature will manage to hold her own, and that the bush will remain in perpetuity to form the appropriate setting of the wild and romantic scenery.
(3.) Scattered throughout the two Islands are numerous portions of country where the contending forces are pretty equally balanced—the cattle and the fire doing a considerable amount of damage, while Nature displays a marvellous power of resistance and recuperation. This class of country occurs principally in hilly and broken districts of moderate elevation, where the soil is of too poor a quality to take grass readily. It is frequently of large extent, and often abounds in scenery of great variety and beauty. A general feature will be at once remarked: that the bush is chiefly confined to the gullies, while the sharp crests and rounded backs of the ranges are covered with fern or scrub tea-tree. The reason of this is obvious. The fires which swept over the dry and exposed surfaces naturally died out when they reached the damp and sheltered hollows. Occasionally, extensive areas occur where even the most exposed ranges still retain their virgin mantle. This happens when some natural obstacle—as a river, a deep ravine, or a rocky cliff—- has prevented the flames from getting a start on the block. Such wooded areas are not uncommon in localities where the soil is too poor and the surface too broken to make farming a profitable undertaking, or where the bushman has not yet made his appearance. Sooner or later, however, a road or telegraph-line is cut through the thick of the bush, or a settlement laid out in the vicinity, when the balance is upset, and the whole aspect of things rapidly alters; as, once the fires find an entrance, they burn year after year, gradually denuding the most exposed spots, and continuing on until they are once more met by some natural obstacle. A notable instance of this may be seen in the case of the Puhipuhi State Forest, between Whangarei and the Bay of Islands, a few years ago the most extensive kauri bush in the country, and estimated to contain some 400,000,000 ft. of that valuable timber. From mistaken
economy, in order to save a few miles of posts and wire, a telegraph-line 3 chains wide was cut through the very heart of the bush, and at the same time a settlement was laid out on the margin at a place where a heavy kahikatea swamp would for many years have prevented the encroachment of accidental fires. What any bushman would have foreseen was not long in happening. The fires on the telegraph-line were soon joined by those which spread from the settlement. The bush was first gutted and then swept; and at the present time the greater portion of this magnificent forest is destroyed. The same thing is going on on a large scale around the village settlements in the north, in every mining and timber district, and to a greater or lesser degree wherever a new encroachment is made.
4. Changing Character of the Bush.
In view of the altered conditions to which the bush has to submit, we shall not be surprised to find that the surviving portions are generally undergoing important changes in character and appearance. We have already noticed the effect of the presence of cattle and pigs in poaching the soil, lacerating the roots, and removing the protective covering of the undergrowth. This, however, is only the beginning, for presently a general and gradual decay sets in, and the more delicate trees—as the tawa, mahoe, kahikatea, and a host of others—die out in rapid succession, leaving the hardier varieties—including most of the pines—standing; and even of these the full-grown specimens generally succumb sooner or later at a rate proportionable to the pressure of the new conditions, and to their own powers of resistance.
5. Second Growth.
Nature, however, does her best to restore the damage done to her domain; and on the ground thus opened up, and indeed very often over large areas that have been wholly cleared, a “second growth “of the non-edible varieties soon makes its appearance, and under favourable circumstances frequently attains to very respectable dimensions, though both in size and variety it is far inferior to the original bush. Occasionally this second growth exhibits itself in seedlings from the surviving trees, as in the case of totaras, rimus, miros, beeches, and kahikateas, when a thriving young family may be seen surrounding the old forest patriarchs, or taking their place when they are removed or die from accident or exposure; but more generally it is composed to a large extent of varieties which have hitherto been absent or inconspicuous. The character and appearance of the second growth vary greatly, according to local conditions. As a rule, one or two species
seem to take the lead in particular localities. Thus, near Whangarei are found handsome coppices almost entirely composed of totara : on the broken ground round the Taranaki coast the white-leaved wharangi or pukapuka is chiefly prominent; the makomako, or settlers' “light-wood,” springs up over the clearings on the Mount Egmont slope, and on similar light soils elsewhere; on the uplands of the Nelson Province the beech encroaches on the cultivated lands; the terraces between the White Cliffs and the Ngatimaru country, in Taranaki, have a character of their own in the groves of waving korau fern-trees; while on the clay ranges in the vicinity of Mercury Bay the dark cone-shaped rewarewa grows with a regularity suggestive of artificial plantation. The same thing may be seen in the case of the fuchsia, the yellow kowhai, the ake, the towai, the tipau, the houhere, the whau, the ngaio, and a host of other minor forms, each of which seems to seek a place where it can flourish by itself, or where for a time at least it can form the principal feature.
The great exception to this rule is the tea-tree, of which there are two principal varieties—the manuka and the kahika-atoa. The tea-tree is the most interesting and important constituent of the “second growth”; it is practically a constant quantity, thriving equally on almost all soils and in nearly every situation—high and low, wet and dry, exposed or sheltered, it is all the same to this hardy and vigorous plant. Distributed, as the late Mr. T. Kirk states,* over all districts from the Three Kings to Stewart Island, and even to the Snares, it is equally at home on the northern gumfields, the pumice plains of the interior, the swamps of the lower Waikato, amid the ocean spray of the storm-swept promontories, and the steam and sulphur vapours of the hot lakes district. Everywhere adapting itself to circumstances, on barren and exposed situations it flowers and seeds as a plant 2 in. high, while on rich alluvial bottoms it attains the dimensions of a handsome forest tree. The tea-tree is the connecting-link between the old and the new. Though freely burning green in its scrub state, and so helping to spread the fire into the surrounding bush, if it gets a chance it acts as the nursing mother of the new growth. On the clay lands of the north, wherever it manages to escape the fire for a few years, seedlings of the original trees invariably appear under its shelter, among which it is not uncommon to find healthy young kauris, tanekahas, and other forms never seen in the open; and in places where it has survived for a lengthened period the species becomes gradually more numerous, so that it requires an experienced eye to distinguish the new growth from the original bush.
[Footnote] * “Forest Flora of New Zealand,” p. 236.
A very perfect example of the second growth may be seen on an old pa (Okuratope) at Waimate North, which is particularly interesting and instructive, as the period can be approximately defined during which it has taken place, The pa is situated on the crest of a clay ridge cropping out through the volcanic country, and is surrounded on three sides by heavy bush, the fourth being bounded by a deep swamp. It was occupied by the great chief Hongi in 1814,* but appears to have been deserted soon after, since when the bush has grown up undisturbed; and at the present time it is covered by a dense growth only distinguishable from the virgin forest by the smaller size of the trees; in fact, were not the attention arrested by the form of the earthworks; which are in almost perfect preservation, the difference might easily pass unnoticed. Within the small area of 2 or 3 acres almost all the trees of the adjacent bush have made their appearance, and it is interesting to see the manner in which the different species have taken advantage of the varying local conditions. On the top, where the crest of the hill has been levelled off to form the upper platform of the pa and the hard clay subsoil is exposed, the ground is occupied by a tall thicket of tea-tree intermingled with a few tanekahas and other trees only found in such situations. Surrounding these a line of towais—some of them as much as 3 ft. 9 in. in circumference—cling to the almost perpendicular face of the ramparts. Numbers of the same tree, together with the rimu and totara, appear on the terraces. Fern-trees have sprung up in the vegetable mould accumulated in the ditch, while descending the outer slope, towards richer soil, the species become more numerous, and the new growth shades off almost imperceptibly into the original bush. The whole place supplies one of Nature's object-lessons, in the study of which, however, we must bear in mind that forty or fifty years ago there were but few cattle running at large, and that consequently the struggle for life was not nearly so intense as it is at present; in fact, were a similar piece of bush now removed in a settled district it would stand a. much poorer chance of recovery.
6. Imported Trees, &c.
Any speculation on the future of the New Zealand bush would be incomplete without some notice of the introduced trees and shrubs that have gone wild. Of these, the most important are the willows and Australian wattles, the furze and sweet-briar, the common bramble and one of the thorny
[Footnote] * The pa -was visited and described by Mr. Nicholas, who accompanied the Rev. S. Marsden to New Zealand in 1814.
hakeas. The willows have mostly originated from trees planted with a view (generally mistaken) of retaining the hanks of rivers running through alluvial country. From these broken pieces are carried down by the freshes, and quickly take root, forming continuous groves along the margin, and frequently islands in the bed of the stream. Hundreds of miles of river-banks have been clothed in this way in many parts of the country. So far the varieties have been confined to the tall straight osier and the weeping willow; and, although others will doubtless be introduced from time to time, these will probably hold their ground by reason of their large and vigorous growth. The Australian wattles seem to have, been among the first plants imported into the colony. Several species are found about most of the older settlements, where they have flourished and increased as the native bush has died away. The furze, originally used as a hedge plant, and the sweet-briar, probably intended only as an ornamental shrub, have also come to stay, and in many places have taken complete possession of the country, so much so, in fact, as to considerably depreciate the land-value. The common bramble has made an unwelcome appearance in the bush districts north of Auckland, where it threatens to become such a nuisance that the various agricultural societies have already been trying to devise means for its eradication. And in several spots between the Bay of Islands and Whangaroa the hakea is spreading rapidly among the fern and tea-tree, and forming an impenetrable thicket wherever its winged seeds light on a patch of burnt ground. The foreign element has already added a new feature to the forest flora of the country, which will be more and more, conspicuous as the present species spread further afield, and as new ones are introduced.
7. Future Diminution of Fires.
For a long time to come the fires will overrun the country more or less every dry season, but after a while they will gradually decrease, both in extent and destructiveness.
The area of bush land available for settlement is limited; and after the dead timber has been consumed, and the country reduced to cultivation, there will be nothing to carry the flames over a wide extent. We may therefore confidently hope that in a few years such terrible conflagrations as have lately overspread whole provinces will be things of the past, and that the fires that do occur will be comparatively small and local.
The same thing will happen, though much more slowly, on the large areas of open land now covered with fern or tea-tree. As the cattle and sheep find their way over the run the surface growth is consumed or trodden down to some extent, and grass springs up from the seed carried in their droppings. It
is true that the fern or tea-tree is not long in reasserting itself, but the animals continue their work, and sooner or later the grass must get the mastery; so that the native growth, if it does not disappear altogether, will be broken up into patches, when a fire of large extent will become impossible.
This comparative cessation of fires will have a marked effect on the country. By degrees the dead timber, which now forms such an unsightly fringe to the bush, will decay and disappear, and, instead of furnishing fuel for further destruction, will help to fertilise the ground. The trees which are able to bear the new conditions will take on fresh vigour, and the seedlings, whether within the forest or forming an independent growth, will have an opportunity of coming to maturity.
8. The Residuum.
This state of things, however, is still in the far distance, and when it does take place the residuum will be much smaller than is generally supposed. The rate of destruction is greater at the present time than at any former period; and it is probable that for some years to come it will increase rather than diminish. Bush settlement is being pushed on all over the country to meet the wants of the growing population, and the timber industry is keeping pace with an extending market. The kauri and kahikatea forests are being rapidly exhausted, and every available stick of rimu, totara, black-pine, birch, and puriri is being removed from the general bush to supply material for house- and ship-building, for bridges and railway-sleepers, for wharf -piles and telegraph-poles, for mining-props, posts and rails and palings and shingles, for gum-boxes and butter-kegs, and so forth—and, as the favourite timbers grow scarce, recourse will necessarily be had to the now lesser-known varieties. So far any attempt at conservation has been futile, if not actually mischievous, and will doubtless continue so until the community awakens to a sense of its loss, when reform will come too late to be of much use. Arguing, therefore, from present facts and tendencies, we must face the conclusion that, with the exception of the “second growth,” together with certain comparatively insignificant remnants scattered through the broken districts from which most of the character will have departed, the permanent residuum of the New Zealand bush will be practically confined to the high mountain-ranges, more especially in the south and west, where the land is generally rugged and precipitous and the rainfall abundant.
In predicting the appearance of the bush of the future it is, of course, impossible to deal in other than very general terms. As at present, it will vary with every accident of soil, climate, and aspect. But, speaking generally, we may. expect
to see an infinite gradation between the portions which remain practically in their virgin condition on the mountain heights and sheltered gorges and the outlying fragments in the lower and cultivated districts; and that, in proportion as it is affected by the new conditions, the bush will be more clear and open, the trees fewer in variety, and of a shorter and bushier habit. There will also be an increasing admixture of the foreign element, and less and less of the original undergrowth.
Behaviour of Individual Trees.
As a help towards the solution of the question at issue, I append a few short notes on the behaviour of some of the most important trees under the ordeal to which they have to submit.
The Kauri.—Naturally the kauri first claims our attention. It is painful to think that this noble and beautiful tree is destined within a comparatively few years to become practically a thing of the past. As noticed in my former paper, the floor of the kauri bush is covered with a thick coating of vegetable humus (pukahu), which is rendered highly inflammable by a mixture of dead leaves, particles of gum, and scales dropped from the resinous bark; so that, even if the trees are not felled for timber, they run a constant risk of being killed by fire. Under very exceptional circumstances a few single specimens, or small clumps isolated in the mixed bush, may manage to survive in some deep and sheltered gully; and these, together with the “rickers,” too small to be worked to advantage, and the seedlings in the “second growth,” will soon be all that is left. After the fire has passed two or three times over the site of a kauri bush the land generally settles down to a short growth of tea-tree scrub.
The Rata.*—-The rata, or at least the northern variety, is also to a great extent doomed to disappear, though generally by a different process. Starting in life as an epiphyte among the branches of some lofty tree, the rata sends down its aerial roots, which on reaching the ground thicken and gradually enlace the trunk of its supporter, often squeezing it to death, at the same time putting out great spreading branches above, and eventually becoming the largest and most conspicuous tree in the forest. Robust and vigorous as it appears, however, it cannot long stand the new conditions. First we miss the grand crown of crimson bloom; next we notice the gradual shrinking of the rounded tufts, of foliage; and soon the spreading limbs are but a giant cluster of stags' horns,
[Footnote] * For an excellent account of the rata, vide Kirk's “Forest Flora of New Zealand,” s.v.
lichen-coated, and dropping to decay. The great coil of twining roots are almost superficial, and fail to draw their nourishment from the bare and hoof-trodden ground.
Mountain Rata.—For the mountain rata of the South there is a happier prospect. It is a true tree, better rooted than its northern congener, and with its advantages of climate and situation will probably continue one of the most conspicuous features of the alpine scenery.
Puriri.—The puriri, as Mr. T. Kirk has noted, is the only tree which is able to resist the strangling pressure of the rata, and it is one of the few which, in anything approaching an adult stage, will survive the removal of the surrounding bush. It will stand any amount of hacking and cutting about; and even when partly destroyed by fire—so long as the bark is not burned round the root—it will renew its youth by a fresh growth from the trunk and lower branches. Unfortunately, the species is of limited distribution, being confined to the upper half of the northern Island; and, as the timber is in great, request for railway sleepers, fencing-posts, &c., all the best specimens are rapidly disappearing. Moreover, there is not much chance of its renewal, except in places inaccessible to stock, as the seedlings are quickly eaten off. Still, the puriri is a long-lived tree, and probably existing specimens will survive for an indefinite period. An example of its vitality may be seen in the old mission settlement of Waimate, where several beautiful clumps have held their ground against the cattle in enclosed paddocks for at least fifty years. Even after death the puriri is a noble object, as, bleached to a snowy whiteness, it stands with all its branches perfect long after every vestige of the surrounding bush has disappeared, both above and below ground, apparently insensible to decay.
Kahikatea.—The kahikatea, or white-pine, is distributed over the greater part of New Zealand, and is found in greatest abundance in low and swampy situations, where it frequently forms continuous forests of large extent. Specimens of a harder variety are common in the mixed bush on higher ground. Generally easy of access, and affording a useful timber, it is being largely removed for mill purposes. The kahikatea is a delicate, tree, and does not long survive under altered circumstances; in fact, during the last few years immense bushes have disappeared with, marvellous rapidity, their sites being now occupied by cabbage-tree, flax, and raupo swamp, according to the comparative wetness of the situation. In the drier portions the ground is often covered with a close crop of seedlings, many of which attain a considerable height. It is doubtful, however, if they will equal the parent growth.
Other Pines.—Of the other so-called pines the totara and rimu—both noble trees and of wide distribution—are the most important. They are, however, much sought-after for the excellence of their timber; and it is only a question of time when all the best specimens will be removed in all accessible situations. Fortunately, the seedlings are cattle-resistant, and perfectly hardy; and the totara and rimu, together with the matai, tanekaha, miro, &c., will form an important element of the bush of the future.
Beeches.—The beeches, of which there are several varieties, are chiefly confined to the South Island, where they frequently form continuous bushes of large extent. The timber is used for all purposes, and the best portions have been already cut out. Mr. Kirk has pointed out a property of the beech-forest which, with the exception of the tea-tree, is quite unique in the New Zealand bush—viz., its-power of renewing itself from seed, all that is required for its perfect restoration being the exclusion of cattle (vide “Forest Flora of New Zealand”: Art. Fagus).
Tawa.—The tawa, though unimportant as a timber tree, deserves mention on account of its large size, wide distribution, and handsome appearance. It is common to all parts of the North Island, and formed a few years ago one of the most attractive features of the extensive forests of Taranaki, Hawke's Bay, and Wellington, now mostly destroyed by fire. It is a tall, graceful tree, with a clean trunk and light willow-like foliage. The timber until lately was considered to be of little value except for firewood, on account of its perishable nature, but of late a use has been found for it in the manufacture, of butter-cases, for which it is excellently adapted. The tawa is, unfortunately, one of the first trees to disappear, as the roots stand out above the surface, and are covered with the very thinnest of bark. In many districts where the bush is otherwise in fairly good preservation it has almost entirely perished.
Towai.—The towai is a large, handsome tree, chiefly valued for the tanning properties of its bark. It is distributed all over the colony, and has the distinction of being the only tree above the size of a mere bush which grows in the open fern land, where it quickly springs up from the root after a fire. It is found in great abundance on steep rocky river-banks, and flourishes on high and exposed situations. Although its roots are very superficial, the towai is fairly cattle-resistant, and is destined to figure largely in the bush of the future.
Titoki.—Though comparatively inferior in point of size, the titoki has a strong claim on our attention from its extreme hardiness under all conditions. It is never touched by cattle, and is often found green and flourishing in the midst of the
dying bush, as well as in the “second growth.” It is a remarkably handsome tree, with a dark glossy ash-like leaf and bright scarlet berry, and affords an excellent timber for all purposes where toughness and elasticity are required.
Pittosporums.—The Pittosporums form a large class, and are distributed more or less all over the country. They are of no great size, and of little account as timber trees; but, being extremely hardy and perfectly cattle-resistant, their graceful outline and beautiful foliage add greatly to the appearance of the forest. Like the titoki, they are often found in increasing quantities as the old bush dies away, and it is not uncommon to meet with healthy plants springing up in shrubberies and garden-ground from seeds carried by the birds.
Fern-trees.—Much of the characteristic beauty of the New Zealand bush is owing to the presence of the fern-trees scattered through the undergrowth. Although botanists are able to distinguish a larger number, they are generally divided by bushmen and ordinary observers into three species.—viz., the tall waving korau or mamaku, the more robust ponga, and the short thickly growing wheki. The two latter are not much molested by cattle, unless the place is very heavily stocked, but the succulent fronds of the korau are immediately eaten whenever within reach. As, however, this species chiefly affects low and damp situations, it is frequently found in deep, narrow watercourses, where it forms beautiful palm-like groves secure from the attacks of the enemy.