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Chapter VII. — The Forest of the Past

page 46

Chapter VII.
The Forest of the Past.

Although Tutira when first taken up as a sheep-run was a wilderness of bracken (Pteris aquilina, var. esculenta), it had nevertheless been within a very recent period wholly under forest. In the oozy bog runnels of the central run, where the current scarcely stirs the floating weeds or shivers the tall green reeds, timber is plentiful. The swamps, undrained and drained, are full of it. Through the shrunken surfaces of the latter protrude in the drier parts dark peat-preserved boles. In the great drains scoured out by flood-water are to be found the crowns and octopus-like roots of trees. Timber lies in the basin of every lake, lakelet, and tarn on the run. It shows beneath the turf of grassed lands whiter in the morning frosts, browner in summer droughts. Surface timber also, chiefly totara (Podocarpus Totara), is, or rather was—for thousands of posts and strainers have been split from it—plentiful. It was most abundant on the most arid parts of the trough of the run. Thereabouts there had been a lesser growth of fern, a lesser accumulation of inflammable material. The fires, which from time to time used to sweep the countryside, had been from lack of combustible matter less fierce and less frequent in these localities. Great lanceolate-shaped spars curiously gouged and chiselled by fire were common, whilst here and there entire boles remained almost intact. Some of these prone trunks were of great girth; one lying in the open gave a diameter of twelve feet.
Totara bole deeply sunk into the soil.

Totara bole deeply sunk into the soil.

page 47 Another deeply sunk into the soil can have been scarcely less than fifteen feet through. Huge boles of less durable species, their shrunken bulk unmarked by the least mound, lie to this day absorbed in the dark gritty soil, unseen and unsuspected until advertised by fire. They appear to have disintegrated into mould, or perhaps more correctly to have been reduced by former fires into a sort of charcoal. It would seem impossible that the material of these rotted boles could once again take form—these dry bones live. They do so nevertheless. After a fire has swept the bracken the long - vanished giants will sometimes rekindle and burn for days in a slow, smokeless smoulder.
Shape of fallen tree rediscovered by fire.

Shape of fallen tree rediscovered by fire.

As the invisible image on a photographic plate is revealed by chemicals, so by fire is the entire shape of the fallen tree rediscovered. At first on the dark ground it lies flat, a fragmentary skeleton, the massy trunk, the mighty boughs, portrayed in deep soft masses of grey ash, which after rain becomes an emerald fur of softest velvet moss. The tree by a natural miracle, again after long death supports a verdure deeper than in its leafy prime. Nor does even then change cease. The skeleton of the prone tree can only for a few days perhaps be visible in ash, for a few weeks in moss. It remains more durably marked in scrub. Better fed on the potash, this scrub manuka (Leptospermum scoparium) page 48 soon out-tops the surrounding growth and stands forth in strange arbitrary lines, a record of the past, undecipherable except to those who have watched each stage.

It is throughout the trough of the run that timber is most evenly distributed as well as most plentiful. On the marls of the east, landslips perpetually occurring have contributed in no small degree to its disappearance. There it has been swept away, and lies buried deep below the surface. The slower-growing more durable species of tree, moreover, have not had time to establish themselves firmly; as seedlings and saplings they have been uprooted and rushed downhill in avalanches of earth.

Besides evidence afforded by timber preserved in water, buried in mud and marsh, and strewn irregularly over the surface of the run, there are other convincing proofs of an ancient forest. Many portions of the station are so honeycombed with holes and hollows, the result of rotted or burnt-out roots, that they are unsafe to ride over except at a walking pace.

The trough of the run is marked too by innumerable hummocks, their longitudinal edges running at right angles to the quarter from which blow the most violent gales. They are so numerous, and the hummock form so invariable, that it is certain these boles have been levelled by storms from the west and nor'-west. The hummocks scattered over the whole of central Tutira denote, too, a forest overblown when dead, not green, in the first place destroyed by fire, then uprooted by the prevailing winds. In green New Zealand woods great trees do not readily fall; not infrequently they are supported by neighbouring trunks, or at any rate their natural angle of fall is deflected by masses of lianes, creepers, and vines. Often they rot away standing, torn to pieces by the kaks parrot (Nestor meridionalis) in search of grubs.

Hummocks—Central Tutira.

Hummocks—Central Tutira.

Lastly, there is a very pretty little bit of evidence afforded by two ferns which could never have established themselves under present conditions. Each of them is a forest species—the one, the umbrella fern (Gleichenia Cunninghamii), being usually found on wooded spurs; the other, a maidenhair (Adiantum diaphanum), on the forest floor itself. page 48a


page 49 These survivors of an altogether different vegetative covering still manage to exist on modern Tutira though stunted and depauperated.

Although, however, there can be no question as to the existence of this former forest, its duration in time, date of disappearance, and cause of decay are problems not so easy to solve. Even taking into account the fact that subterranean soakage has stolen away the manurial values of leaves, branches, and bark—even, I say, taking that into account,—it seems extraordinary that soils for any time under forest should have become so barren in so brief a time. Nine-tenths of Tutira have been unable to support ryegrass for a single season, yet it is certain that forest had not long disappeared off the face of the ground when settlement took place.

That soil and subsoil do not seem anywhere to have been thoroughly intermixed, throws but little light on the question of the duration in time of this primeval forest. As has been explained, more often than not trees do not fall when dead,—they decay upright, the great boughs snapping indeed with age and weight of epiphytic and parasitic growths, the stem as often as not mouldering away, devoured by insect life and torn to bits by birds. Admixture of humus, pumice grit, and red sand has taken place no doubt to a certain extent, yet the yellow hummock material exposed by the overthrow of a fire-swept forest shows distinctly different from the top twelve inches.

In regard to date of disappearance, the oldest natives I have questioned—men of eighty or ninety—have no recollection themselves of great forest fires, nor have the memories of such events been handed down in tribal history. It is probable that no huge conflagration has occurred, but that the disappearance of the old-time forest has been piecemeal. This negative evidence of a tardy retrogression is borne out by the amount and by the condition of timber in various parts of the run. The differences can best be illustrated by portioning the station into imaginary belts of equal width. Thus, throughout the most coastward belt, little surface timber will be found to remain even on sites favourable to its preservation. Another belt, more inland, will furnish surface timber in small quantities, bog timber and a profusion of hummocks with roots completely rotted. A third felt, still farther away from the coast, will provide a greater amount of both surface and bog timber; hummock markings are rather less worn with wind, frost, and rain, roots and stumps are not altogether page 50 decayed. A fourth belt will give us tall blackened boles, still here and there erect, also immense numbers of fallen trunks but partially decayed. This belt must have flourished as green forest within ten or fifteen years of my arrival at Tutira. Nearly one thousand acres of trees must have perished by fire about '65 or '70, for in '82—the date of my arrival—a third of the timber was still erect; thousands of boles, blackened and charred, but still branched, stood perpendicular, eighty or ninety feet high. A fifth belt would include the ranges and give us the growing bush of the present day—the last remnant of the primeval forest that once shaded the whole run.

This slow retreat towards the mountains is not likely to have been caused by change of climate. It is of too recent date to be thus accounted for; we must seek another reason for the triumph of bracken over woodland. Sometimes I incline to a solution, only the barest outline of which can be given. The latest considerable influx of islanders from outside took place, it is believed, about five hundred years ago. These immigrants from wheresoever they came probably dispossessed tribes neither so virile nor so numerous. There was no bar, therefore, to the rapid increase and multiplication of the dominant race. The ancient Maori was an excellent cultivator, keeping his crop grounds in a high state of tillage, carefully weeded, dug, and hoed.

Their earliest settlements as an island race were planted on coastal lands. Now wherever man works, one of his most helpful agencies is fire. Maybe the fires of these immigrants five centuries ago began that destruction of the forest, not yet quite complete when Europeans arrived in Hawke's Bay. In dry seasons these fires doubtless ran far beyond the limited Maori clearings; we can be equally certain that fern took possession of the rich loose mould thus opened to the sun. Furthermore, a fern crop, once established, would, every fourth or fifth season, be sufficiently thick to burn; the flames would on each occasion destroy a new breadth of timber. Even the small number of seedling trees able to compete with the bracken would never attain to more than four or five years' growth. Thus bracken would take possession of the coastal regions first, then gradually work inland to damper, colder areas. Fire would also be largely used as a means of easy access to inland hunting-grounds. There can be no doubt that the aboriginal forest was destroyed by fire.

There is equally little room for doubt that if fires, mankind, and page 50a
Yellow Kowhai

Yellow Kowhai

page 51 stock were banished, the woodlands would re-establish themselves. Twenty-five years would see the surface, so painfully grassed, once again in fern; one hundred would see forest reclothe the countryside. Within my own period, an example of this general tendency has presented itself. In '83 a part of the run known as the “Sandhills” had been fire-swept. It lay black and bare except for one patch of five or six acres of fern. This oasis of ravine or dene, evidently particularly damp even in summer heat, lay on steep slopes facing south-east, but with no other apparent defence from the fire which had desolated the surrounding lands. Unscorched in '83, it has since then again and again escaped periodical fires purposely lighted. In forty seasons it has been transformed from fern to scrub and from scrub to light bush. It contained in the 'eighties a great deal of tall fern together with a proportion of small tutu (Coriaria ruscifolia), koromiko (Veronica salicifolia), and manuka (Leptospermum scoparium). Later, appeared slender matapo (Pittosporum tenuifolium) and makomako (Aristotelia racemosa), fuchsia (Fuchsia excortica), hinahina (Melicytus ramiflorus), kowhai (Sophora tetraptera), and rangiora (Brachyglottis Rangiora); the original shrubby tutu and koromiko grew almost into trees; the manuka stiffened into poles; tree-ferns, lawyers (Rubus australis), and supplejacks (Rhipogonum scandens) appeared as under - scrub, the fronds of the stifled bracken grew further apart. Seedlings and saplings of the larger forest species, white pine (Podocarpus dacrydioides), rimu (Dacrydium cupressum), and totara (Podocarpus Totara), established themselves. With the lapse of another twenty-five years light bush, the precursor of forest, would have possessed the little dene.

Tutira, then, has been at one period entirely covered with forest, bush of a lesser size and more ephemeral nature possessing the eastern coastal belt, timber of great girth and of a more durable character flourishing throughout the trough and western portion of the station. Consequent on forest fires a gradual general retreat inland of these woodlands has been traced. For two or three centuries maybe eastern Tutira has been bare of trees; on the other hand, in the central run a patch of one thousand acres has been destroyed only as recently as the 'seventies. On the far west, relics of the ancient primeval forest still grow green.