Art. IX.—Notes on the Plants best Adapted for the Reclamation of Sand Wastes.
[Read before the Auckland Institute, 6th October, 1873.]
As attention has been drawn to the importance of preventing the further inland extension of our coastal sand wastes by the recent papers of Mr. Whitcombe * and Mr. Stewart, † it seems desirable to point out the various indigenous and exotic plants available for the purpose, and to state their respective advantages and disadvantages so far as demonstrated by actual experience or close observation.
Mr. Heale has well shown that, as a general rule, it will be found much more difficult to reclaim the sand wastes on the west coast of the North Island than those on the east, on account of the greater set and force of the wind on the former. While assenting to the general truth of this statement, I am led to the belief that in all except perhaps a few peculiar localities, the object sought may ultimately be obtained by commencing the work of reclamation at high-water mark, since the added sand, except in the case of moving sandhills, is chiefly derived from the space between tide-marks. If, therefore, we can succeed in arresting this at the extreme verge of high water, the mass will accumulate so slowly, owing to local eddies and coastal dispersion, as in most cases to admit of the growth of arboreal vegetation forming a permanent barrier.
When the sand is but slightly exposed to the action of the wind, the process is very simple, or rather a number of simple processes may be adopted.
[Footnote] * Trans. N.Z. Inst., Vol., p. 108.
[Footnote] † See Art VIII
Where young plants of the marrem or the lyme-grass can be procured, they may be placed about fifteen inches apart, by simply making an incision with a spade, inserting the plant, and pressing the adjacent sand about it with the foot. Festuca littoralis, which is common all round the coast, might be used for the same purpose; Poa australis var. lŒvis, an abundant grass from Port Waikato south wards, is also available, as are the pingao (DesmoschŒnus spiralis) and the Spinifex hirsutus, which may be obtained in unlimited quantities on all coast sand-hills in the colony, although they are not so effective as the marrem, lyme-grass, and maritime fescue.
Zoysia pungens, a creeping rooted grass, but with herbage rarely exceeding two inches in height, might be sown or planted amongst the larger kinds; its herbage is succulent, and it is eaten with avidity by sheep and horses, while it forms a remarkably dense, compact sward. Poa breviglumis, a grass more common on sandy shores in the South Island than in the North, affords a larger yield of herbage, and may be either sown or planted. Other suitable plants for this purpose are mentioned in the appended list.
In a few exceptionally quiet spots, grasses of a more nutritive kind might be sown at once: the rat's-tail, or chilian grass of the settlers, the doab grass, buffalo grass, and the common meadow grass are well suited for this purpose, alike from their creeping roots and dense yield of herbage. The sheep's fescue grasses are also of great value.
The plan of forming ropes of seeded hay, and fastening them on the sand, has been described at length by Mr. Stewart, so that I need not refer to it here.
In spots where moisture percolates through the sand for a portion of the year, the common water-cress might be sown or planted; even if the supply of moisture failed during a protracted drought, the matted roots and decaying herbage would prevent the surface from being disturbed by the wind, and the plant would start into luxuriant growth with the first showers.
In partially-sheltered valleys amongst sand-hills—such, for instance, as are found near the Manukan Heads—it might be worth while to try the experiment of sowing wheat with subterranean trefoil and the native Poa breviglumis. A small yield of grain might be expected, but the benefit to be derived would arise from the decaying roots of the wheat, and subsequently of the trefoil, affording additional nourishment for the meadow grass, so that a compact sward would be formed more speedily than by the ordinary method.
But in all cases, in order to afford protection at the most vulnerable point, it will be advisable to plant a belt of coarse-growing plants or small shrubs capable of enduring the spray of the sea at high-water mark. This should be of several yards in width, varying according to the nature of the situation, degree of exposure, etc., and may be composed of toe-toe grass (Arundo conspicua),
prickly toe-toe (Cyperus ustulatus), and sea spurge (Euphorbia glauca), all of which are abundant on the coast, and in many places may be planted without subdivision. The sea mallow (Lavatera arborea), of which seeds may be collected in the neighbourhood of every New Zealand port, would form a valuable addition to the native plants adapted for this purpose.
In places but little exposed to the wind it would not be absolutely necessary to introduce shrubs or trees, although such a course offers many advantages. The osier and the white willow are well adapted for such localities, and may be readily increased by cuttings, so also the weeping willow, the sea buckthorn (Hippophae rhaamnoides), the pohutukawa, ngaio, and others to be presently mentioned. The best of all known trees for this purpose, however, is the pinaster, but plants not more than one or two years old should be used; in the latter case they should have been, transplanted the first year.
But the process is not quite so simple in localities exposed to the full action of the wind: here it is imperative at the outset to provide temporary protection by covering the surface with branches of evergreens, straw, rushes, reeds, etc.; or by erecting a stout wattled fence; by thatched hurdles; or, best of all, by a fence of close boards. In not a few spots it will be necessary both to erect the fence and to cover the surface with branches, or the most available substitute.
It is obvious that under such circumstances planting cannot be undertaken to any great extent, and must be restricted to spots where it is absolutely necessary, and to such objects as creeping-rooted grasses, etc., some of which, will not only endure the diminished amount of light and air caused by the overlying branches, but will, for a time, derive considerable benefit. But as grasses alone, even if thoroughly established in such exposed situations, would soon become buried by the moving sand, it will be necessary to employ trees and shrubs to a large extent; and these can only be established by sowing, which is happily the most economic method. The most effective plan would be to commence at high-water mark, and erect a fence, as already suggested, at right angles to the prevailing wind; then to sow a belt with the seeds selected, which should be immediately covered with overlapping branches of evergreen trees, lightly pegged down, or secured with stones. The width of the belt must depend upon the violence of the wind, degree of exposure, etc.; but too much should not be attempted at once. This belt of itself would, in a short period, form a shelter for another belt, and so on until the entire area was reclaimed.
The best mixture I can suggest for general purposes of this kind in the Colony is :
1 lb. broom (Spartium scoparium).
1 lb. pinaster (Pinus pinaster).
½ lb. tarata (Pittosporum crassifolium).
½ lb. cottonwood (Cassinia leptophylla).
1 lb. toe-toe (Arundo conspicua).
2 lbs. buffalo grass (Stenotapharum glabrum).
½ lb. sea meadow grass (Poa breviglumis).
The above would be sufficient for one acre. The selection might be varied by substituting any of the plants enumerated hereafter, at the judgment of the cultivator.
As before remarked, it would be advantageous in all cases to plant at high-water mark a broad belt of toe-toe, prickly toe, sea spurge, and sea mallow, or similar plants, of which we have happily a fair choice; also, if practicable, to plant roots of maritime creeping grasses amongst the seeds when sown.
The broom would attain a height of two feet or more the first season, but the pines would not exceed a few inches. In the north the pines would probably overtake the broom and other shrubs about the fourth year, by which time they would require thinning, and the thinnings might be used to protect other sowings. As the thinnings became larger the trunks and roots might be burned for tar and charcoal. In about eighteen or twenty years the trees might be tapped for resin, when the supply would increase yearly. Unfortunately the timber is not so valuable as that of P. sylvestris and other species, although in Central Europe it is used for inside work and for shingles.
The following enumeration of plants adapted for the reclamation of sand wastes is by no means exhaustive. Several Australian and Tasmanian species besides those named would, doubtless, prove available, but my limited knowledge of them does not warrant their inclusion in this list. A Tasmanian Spinifex growing on coastal sands is said to be a great hindrance to travellers, and may be expected to prove especially valuable for our purpose.
The native country of non-indigenous plants is stated in all cases.
A.—Trees and Shrubs.
Pittosporum crassifolium, sea-side tarata, or kihihi.—A fine shrub or small tree, sometimes attaining the height of twenty-five feet; common on sandy and rocky coasts, from the North Cape to Poverty Bay; produces seed freely; a most valuable plant.
P. umbellatum.—Of less value than the preceding; seeds freely.
DodonŒa viscosa, akeake.—Common; on the sand forms a dwarf twiggy shrub; seeds freely.
Corynocarpus lŒvigata, karaka.—A handsome evergreen tree, but will not flourish when exposed to the wind; seeds freely.
Metrosideros tomentosa, pohutukawa.—On sandy and rocky coasts. Auckland.
A fine tree with tortuous spreading branches, endures the sea spray; timber of great value for shipbuilding. This tree and the kauri have contributed so greatly to the prosperity of the Province of Auckland that it is surprising to find no steps have been taken to perpetuate the supply. Seeds are produced freely. *
Leptospermum procumbens.—Australia.—This is stated by Baron Ferd. von Müeller to be of great value for covering sand-hills. I am not aware that it has been introduced into New Zealand at present.
Coprosma baueriana, angeange.—Common on the coast.
Much-branched shrubs or small trees; endure wind and spray; cuttings root easily, and seeds are produced in abundance.
Myoporum lŒtum, ngaio.—Common on all the coasts, and readily propagated by seeds and cuttings.
Hippophae rhamnoides, sea buckthorn, Europe.—Seeds; a branched shrub 2 — 10 feet high, with silvery foliage.
Salix caprea, sallow, Europe.
Salix viminalis, osier, Europe.
Salix alba b. cŒrulea, white willow, Europe.
Salix babylonica, weeping willow, Persia, etc.
The osier is a valuable plant for our purpose, and is readily propagated by cuttings, which may be obtained from the Nelson nurserymen. The sallow and Salix alba may be seen in the gardens of the Auckland Acclimatization Society, but I fear the variety cŒrulea has not been introduced at present.
Populus acladesca, black Italian poplar, North America.
Populus grŒca, Athenian poplar, Levant.
These trees are well worthy of trial; cuttings root freely, and can be easily obtained.
Pinus pinaster var. maritima, pinaster, Europe.—One of the best of all known trees for our purpose, and can be obtained at all the nurseries. It has been so generally planted about Auckland and other places in the colony that seeds can be procured in large quantities. In the south of Europe the seeds form an article of food.
P. pinea, stone pine, Ravenna pine, Europe.
P. halepensis, Aleppo pine, Aleppo.—Inferior to the pinaster; the seeds of the stone pine are larger than those of the pinaster, and more highly valued for food. Both species produce seeds in the vicinity of Auckland.
[Footnote] * It has been asserted that the pohutukawa will only grow on clay soils. On the South Head of the Manukau, which is a mass of blown sand, it is abundant and luxuriant, attaining a large size. Other instances might be stated.
B—Under-shrubs and Creepers.
Hymenanthera latifolia b. tasmanica.
Hymenanthera latifolia c. chathamica.
Rocky and sandy places on the coast, but remarkably local; b., Spirits Bay to Onitangi Beach, rare; c., Chatham Islands, compact shrubs, 2 ft. to 4 ft. high when growing on exposed sandy beaches; increased by seeds and cuttings. Young plants may be seen in the gardens of the Auckland Acclimatization Society.
Ulex europŒus, L., furze, gorse, Europe.—Naturalized throughout the Colony.
U. nanus b. gallii, dwarf furze, British Islands.
Spartium scoparium, broom, Europe.
Naturalized in many places in New Zealand; valuable, and readily propagated by seed. I believe Ulex gallii would prove more effective for our object than U. europŒus, but it has not been introduced into the Colony.
Rubus discolor, blackberry, Europe.—On sands this plant forms dense bushes, almost impervious to cattle. It is naturalized in several localities, and may be increased by seeds or cuttings.
Coprosma acerosa.—Abundant on coastal sands; seeds freely.
Opuntia vulgaris, prickly pear, South America.—Mr. Knorpp states that this plant has been successfully applied in reclaiming coast sands in Madras, but that it has become so abundant as to be a serious hindrance to travellers in certain localities. It has long been cultivated in the Province of Auckland without evincing any tendency to spontaneous propagation; it would prove serviceable in most parts of the North Island, although not in the South. Increased by cuttings, which merely require to be laid on the surface of the sand.
Olearia semidentata.—Said to form compact dwarf masses on the sandy shores of the Chatham Islands, where it is endemic.
Classinia leptophylla, cotton-wood.—Common on sand-hills all round the coast; seeds abundantly.
Leucopogon frazeri.—Common on sands and open places; seldom more than six inches in height; stems creeping, ascending at the tips; seeds.
Vinca major, large periwinkle, Europe.—Naturalized to many places; the trailing stems take root at the tips and speedily form a close covering to the surface.
Veronica speciosa, large koromiko, Hokianga.—Grows on sand, forming a compact, luxuriant bush; easily increased by seeds or cuttings.
V. dieffenbachii, Chatham Islands.—Valuable on account of its peculiar depressed and spreading habit.
Veronica elliptica.—Of similar value to the preceding, but of taller growth.
Muhlenbeckia axillaris.—Common; seeds.
Pimelea arenaria.—Common on all sand-hills and dunes; seeds.
Agave americana, American aloe, South America.—Increases freely by suckers, and might be used in the North Island, but grows very slowly when young.
C—Suffruticose and Sub-herbaceous Plants, most of which cover the
surface with their foliage.
Nasturtium officinale, water-cress, Europe.—Abundantly naturalized.
Crambe maritima, sea-kale, Europe.—Seeds freely, and holds the sand by its thick roots.
Cakile maritima, sea-rocket, Europe.
Portulaca oleracea, purslane, Europe.—Naturalized; sometimes forms a matted turf in the sand, but is only of annual duration.
Lavatera arborea, sea-mallow, Europe.—A valuable plant, withstands the most violent winds, and, notwithstanding its biennial duration, seeds so freely that it is always effective; naturalized at all New Zealand ports.
Ononis arvensis, restharrow, Europe.—Seeds.
Trifolium subterraneum, subterranean trefoil, Europe.—Seeds.
Mesembryanthemum australe, fig marigold.—On all the coasts; cuttings root easily.
M. maximum, M. falciforme, and many other cultivated species, may be advantageously employed.
Tetragonia expansa, New Zealand spinach.—Common all round the coast.
Eryngium maritimum, sea-holly, Europe.—Seeds; a valuable plant, and much superior to the native E. vesiculosum.
FŒniculum vulgare, fennel, Europe.—Naturalized; seeds.
Diotis maritima, cotton-weed, Europe, North Africa.—Seeds; valuable on account of its creeping, woody root-stock and procumbent branched stems.
Tanacetum vulgare, tansey, Europe.—Cultivated in New Zealand; seeds; forms compact masses on sand.
Convolvolus sepium, bindweed.—Abundant.
C. soldanella, sea-bindweed.—Abundant on coast sands, and of great value.
Artemisia abrotanum, southern-wood, Europe.—Sparingly naturalized; cuttings and seeds.
Mentha cunninghamii.—Not rare in sands and moist places.
Atriplex cinerea.—On the coasts of both islands, but rare and local; a dwarf, branching shrub, rarely more than 3ft. in height.
Beta maritima, beet, Europe.—Cultivated.
Salsola australis, saltwort, Australia.—Naturalized on the shores of the Waitemata.
Polygonum rayi, Ray's knotgrass, Britain.—Seeds; grows close to the surface, which it speedily covers.
Euphorbia glauca, sea-spurge.—Common all round the coasts; a most valuable plant for binding the surface, often growing in places exposed to the wash of the sea.
E. portlandica, Portland spurge, Europe.
E. paralias, Europe.
The above are in no way superior to the native species.
E. peplis, sun-spurge, Europe.—This has been recommended by some writers, but, from its annual duration, is of little value. I consider it inferior to the purslane, which is abundantly naturalized.
Iris susiana, Chalcedonian iris, Levant.
I. germanica, Germany.
Seeds and divisions of the root; naturalized in many parts of the Colony, especially abundant at the Bay of Islands; plants of great value from their abundant, fleshy rhizomes and rigid leaves.
Asparagus officinalis, asparagus, Europe.—Seeds; cultivated in New Zealand, holds the sand by its matted roots.
Arthropodium cirrhatum, rengarenga.—Common on the coasts of the Auckland Province.
Cyperus ustulatus, prickly toe-toe.—Abundant throughout the Colony, and of great value.
Arundo conspicua, toi-toi.—Abundant throughout the Colony; seeds; one of the most valuable plants available for coastal reclamation.
Asplenium lucidum, wharengarara.—Abundant, especially near the sea; forms large clumps on the sands in the southern part of the Colony.
D—Sedges and Grasses, chiefly with creeping roots.
DesmoschŒnus spiralis, pingao.—Common on blown sand all round the coast; seeds freely.
Carex pumila.—Common on loose sandy shores.
C. raoulii.—Not uncommon.
C. inversa.—Rare and local.
C. arenaria, sand-sedge, Europe.
Seeds are produced freely, and all the species may be increased by cuttings of the creeping rhizomes, or, in the case of C. raoulii, by division of the root. C. arenaria is more valuable than either of the native species.
Spinifex hirsutus.—On all loose maritime sands the long trailing stems are often 20ft. long, or more, and will root at every joint if fastened down; like the pingao this will only flourish in loose sand.
Paspalum distichum.—Common on beach margins in the North Island, and about Nelson; forms a compact sward in rather moist situations.
Zoysia pungens.—Abundant on sandy and muddy beaches, etc., etc.; forms a dense matted turf; greedily eaten by sheep and horses.
Dichelachne stipoides.—On sands north of the Hauraki Gulf; a fine wiry-grass of tussocky habit.
Sporobolus elongatus, rat's-tail grass, chilian grass.—Abundant in the North Island and Nelson; a strong, coarse grass capable of adapting itself to a great variety of soil and exposure; eaten by cattle.
Psamma arenaria, marrem, Europe.—Cultivated in New Zealand; extensively used in Europe for binding sands. *
Cynodon dactylon, doab grass, India.—Naturalized throughout the Colony; of great value.
Holcus mollis, soft fescue, Europe.—Naturalized throughout the Colony; valuable on account of its creeping roots; endures the sea-spray; herbage of little value.
Aira canescens, Europe.
Glyceria loliacea, Europe.
Poa breviglumis.—Common on sands, etc., especially in the South Island; a grass of great value.
P. australis var. lŒvis.—Common from Port Waikato southwards; resembles Dichelachne stipoides in habit, but is more diffuse.
P. bulbosa, Europe.
Festuca littoralis.—Common on sands in both islands; of great value.
Triticum repens, couch grass, Europe.
T. junceum, Europe.
Creeping rooted grasses of great hardiness, but producing herbage of little value.
[Footnote] * In the course of a recent hasty walk on the beach between the town of New Plymouth and the Sugar Loaves, during the stay of a passing steamer, I had pleasure in observing dead culms of an exotic grass apparently belonging to this species, and which exhibited great luxuriance, being 4ft. to 5ft. in height. I was unable to ascertain if it occurred in other localities in the district, or to procure any particulars respecting its introduction; but, from its being found in several patches of considerable extent and in many widely-scattered and isolated tussocks, it would appear that seeds were scattered on the beach without protection. It is much to be desired that any person acquainted with the circumstances under which the plant was introduced would place a statement thereof on permanent record, with particulars as to date and present extent of diffusion, as precisely as can be ascertained.
[Footnote] A considerable quantity of seed could be collected without difficulty, and, in some cases, offsets might be taken off, so that with comparatively little expense a portion of the beach might soon be fixed. Offsets must, in all cases, be taken off sparingly, so as to disturb as little of the fixed surface as possible.
Lepturus incurvatus, Europe.—Abundantly naturalized on sands in the Auckland Province, but of trivial value.
Elymus geniculatus, lyme grass, Europe.—Of equal value with the marrem.
Stenotaphrum glabrum, buffalo grass.—Increased by seed and cuttings, etc.; of stout procumbent habit, and producing a large yield of nutritious herbage.
It would ultimately prove advantageous to the Colony if a small portion of the money now being spent on public works could be applied to the reclamation of sand wastes. The magnitude of the evil to be remedied is admitted by all who have paid the slightest attention to the subject. In several localities the natives are compelled, year by year, to abandon their cultivations as the sand-wave advances, and settlers are helpless witnesses of the destruction of their paddocks from the same cause. Fences, large trees, and patches of bush, have been overwhelmed within the memory of settlers of comparatively recent standing, and, in some cases, still more serious injury must result unless preventive measures are taken. The danger is not confined to any one district or province; it is general, and demands prompt attention.
While much can be done with the means already at command, there can be little doubt that other plants, both indigenous and exotic, would prove available on actual experiment, and some species may be found to possess greater value than many of those at present known.
The work of reclamation in this Colony is greatly facilitated by the favourable nature of the climate, which allows the employment of many plants not available for the purpose in other countries.
It must be confessed that such localities as the Waikato Heads, and some parts of the Kaipara sand-hills, are calculated to produce an impression of man's inability to cope with nature; but, if we look at what has been accomplished with more slender resources than those now indicated, it will be seen there is abundance of encouragement. In the Gulf of Gascony immense wastes of trackless sand were utterly destitute of vegetation, and during violent storms exhibited a complete change of surface, hills becoming valleys and valleys taking the place of hills, the sand being gradually carried into the interior, and covering cultivated fields, villages, and entire forests. This process of devastation has been completely arrested, and thousands of acres of former sand-waste now yield a handsome revenue, and support a considerable population. To arrest the process of destruction now to be seen in so many localities in this Colony is an object for which we may well venture to encounter the possibility, the probability even, of repeated failures in the certainty of ultimate success.