AN ECONOMIC INVESTIGATION OF THE MONTANE TUSSOCK-GRASSLAND OF NEW ZEALAND.

New Zealand Journal of Agriculture, Volume XVIII, Issue 1, 20 January 1919, Page 1

AN ECONOMIC INVESTIGATION OF THE MONTANE TUSSOCK-GRASSLAND OF NEW ZEALAND.

No. 1. —INTRODUCTION.

By

Dr. L. COCKAYNE, F.R.S.

GENERAL.

AFTER crossing the actual divide of the Southern Alps from the west a point is soon reached at about an altitude of '2,doo ft. in the north to 1,000 ft., more or less, in the south, where the dense forest of the west gives place, all on a sudden, to a curious grassland composed for the most part of brown tussocks. This point marks the . average ' limit of the heavy western rainfall. Frequently such rain extends to the. very margin of the forest, while less than a mile to the eastward the sun is shining, - or, at most, a few drops of ..rain are carried, by. that furious gale which nearly always accompanies the downpour. ' So sharp is this distinction between western forest , and eastern grassland, commencing at the

River Wairau (Marlborough) in the north and ending at the forest of. Southland, ; that hardly a single tree invades the grassland, but the forest stands a dense, dark barrier with clean-cut margin, whence extends eastwards the tussock-grassland. The change in the scene is instantaneousthere is no transitional phase. The average amount of rain and number of'rainy days at this critical linethe junction of forest and grassland—is a fair gauge of the minimum demand of that special forest-association (usually southern-beech — Nothofagus) with regard to rainfall, but it does not indicate how much rain tussock-grassland itself can tolerate, since the extension of the latter plant-formation westwards is barred, not by climate, but by the -mass. Where the forest has been destroyed by fire, and the surface soil not become too greatly eroded, grassland is readily established beyond its natural western limit. Eastwards the tussock-grassland extends,, it may be, to the coast as the main type of vegetation ; but in various localities, especially near, the . coast-line or in mountain-gullies or shady slopes, there were originally considerable areas of forest. These have been greatly reduced by fire, milling, or other causes, so that now, at above 1,000 ft. altitude, the' tussock-grassland of the South Island is more extensive than in the early days of settlement. At a lower altitude much of the plant-formation under consideration has given way before the plough, and now is in permanent pasture or undergoing rotation-farming. Other lowland tussock-grassland, extending southwards to. about the River Waitaki, has spontaneously become danthonia pasture.

There is even yet a good deal of lowland tussock-grassland, but it does not concern this series of articles and the special research they are intended to chronicle, which is primarily connected with the tussock plant-covering, much of which is unploughable, situated on the eastern slopes and in the valleys of the Southern Alps and other eastern ranges. From the economic standpoint this grassland is the main grazingground of the back-country sheep-stations.

The term “montane," as here used, needs a brief explanation. Probably the average length of time during which the main winter snowfall lies upon the ground at different altitudes regulates the distribution of the species and the character of the vegetation of a high mountain. Thus the plant-covering of such a mountain is arranged in distinct belts, each of which has its own special plant-associations, while a number of species are either confined to it alone or much more common on that belt than on any of the others. Obviously, then, each belt provides a different, type of pasture for sheep. The lowest — that extending, according to latitude and climate, from, say, 1,000 ft., more or less, to 3,000 ft., more or less—is here called the montane belt; above this, extending upwards for some 2,000 ft., comes the subalpine belt; and all above this up to the actual summits of the mountains forms the alpine belt.

Although certain tussock-grasses may ascend to the actual summits and be common enough at all altitudes the main tussock-grass community is that of the montane belt. This great grassland spread over an area of some 6,000,000 acres is, as already noted, the .pasture-ground par excellence for. the mountain flocks of sheep of the South Island.

Owing to the treeless character of the montane tussock-grassland and its accessibility it was early in the history of settlement rapidly

converted into sheep-runs, so that at the beginning of the “ sixties ”, of the last century almost as great an area was occupied by sheep as at the present time, while not. a few of the runs date back to the early “ fifties. The grassland under consideration has therefore been continuously grazed for close on sixty years. During that rather long period nothing of moment has been done to improve the carrying-capacity of this grassland, but, as will be seen, quite the contrary has been the case. “It may appear strange,” writes A. H. Cockayne (Trans. N.Z. Inst., vol. 48, p. 155), “ that in New Zealand, where the general trend of farming operations is in the direction of increasing' the carryingcapacity of land, comparatively no, effort is , made towards any improvement in the utilization of the montane tussock-grassland. For the past fifty years the methods adopted have not varied except in one particularnamely, in a change in the type of sheep used.” Again, the same author emphasizes, an important fact when , he says (loc. cit.}, “ They [the montane tussock-grasslands] represent one of the few natural resources of the Dominion that have remained a permanent asset without having to be intentionally modified or specially treated to render them capable of continued production.”

•: An area of montane tussock-grassland, where the tussocks stand thickly side by side, might, at first glance, well be considered pasture of a fairly high quality. Yet the fact stands out-that were such an area capable of grazing one sheep to three acres it would far exceed in its carrying-capacity most parts of the tussock-grassland. Much at the present time will not carry even one sheep to five acres, and some parts are virtually barren. Nor do the above statements of necessity apply to those ■ areas where the plant-covering has been greatly damaged and modified by the presence of rabbits in their thousands. Without going into special details, it stands out clearly that the agricultural position of the montane tussock-grassland is far from satisfactory, but it seems hopeful that methods can be devised for raising its carryingcapacity indeed, such methods may be in practice on certain runs. New methods for improvement must be based on an accurate knowledge of the present plant-covering of the area, of the natural changes taking place, of‘the climate and soil conditions to which the species are exposed, of the effect of the operations of man and his grazing-animals, of the life-histories and physiological requirements of the species, of the germinating-capacity of their seeds, of the histories of the plantassociations, and of other matters connected with the relation of the plants to their, extremely complex surroundings.

COMPOSITION OF THE MONTANE TUSSOCK-GRASSLAND.

A detailed account v of the composition of the montane tussockgrassland. and the differences it exhibits in various' parts of its area may form the subject of some future articles ■ of, this series. It is intended as the study of the grassland proceeds to try and find out with fair accuracy the contents of various types of pasture at different altitudes, aspects, and so on, so as to gain a much greater understanding of the composition of. the grassland than is at present available. Naturally, the all-important ’ classification of the different types of tussock-grassland would result.

Speaking 'quite' generally, and taking the montane tussock-grassland of the South Island in its. entirety, it is made up of some 210 species of indigenous plants which belong to 39 families 'and 98 genera. Even more important from the economic standpoint than the specific distinctions of the plants are their growth-forms, for the actual form of a plant tells. a good deal about its requirements ; in fact, a knowledge of. the growth-forms suitable for a certain environment may give a clue as to what plants of economic value are suited for introduction or experiment. But this matter of growth-forms is too complicated to introduce into this introductory article ; here it need only be pointed out that the tussock form, the mat form, the tufted form, the turf-making form, the rosette form, and the cushion form are of great importance amongst the grasses, sedges, semi-woody plants, and herbs of the grassland. With regard to the shrubs, the leafless flat-stemmed form and the prostrate or dwarf (perhaps creeping and rooting) form are of considerable moment. Annuals are very few in number. Plants whose aboveground parts die to the ground yearly — e.g., the various forms of tutu (Coriaria) — are not many, but such plants may become extremely aggressive, as they can defy fire. .

Besides the indigenous species of the montane grassland , there are more than forty introduced species, some of . them — cocksfoot, red clover, and white clover a much higher food-value than any of the indigenous species. It is doubtless the presence of the introduced plants which has saved the grassland from further deterioration. Some of these plants would not be thought desirable by the farmer of the lowlands, but anything which sheep will eat can fill , a want in the mountain pastures. Amongst widespread plants of this latter class are the following : Sweet vernal grass (Anthoxanthum odoratum), florin (Agrostis stolonifera), ~ red-top (A. vulgaris), Yorkshire fog (Holcus lanatus), meadow-grass (Poa pratensis), broom (Cytisus scoparius), sorrel {Rumex Acetosella), winged thistle (Carduus pycnocephalus), and catsear (Hypochaeris radicata). ■ ' '

The dominant species of the montane tussock-grassland is the fescuetussock {Festuca novae-zealandiae), just as the silver-tussock s (Poa caespitosa), a grass of very similar appearance, dominates the lowland tussock-grassland. These two associations are called “ low tussockgrassland,” to distinguish' them from “ tall tussock-grassland," where the red tussock (Danthonia Raoulii var. rubra), or one of its allies, are the dominant tussock-grasses. Frequently in montane tussock-grass-land the small blue tussock (Poa Colensoi) is extremely common; generally that dark-stemmed spinous shrub, the , wild-irishman (Discaria toumatou), is dotted about here and there. There are many other common members of the association, of which only a few can be cited here— e.g., various species of piripiri (Acaena), the spear-grass {Aciphylla squarrosa), the Spaniard (A. Colensoi), certain turf-making raoulias (Raoulia subsericea, R. glabra), the mountain. groundsel (Senecio bellidioides), and the pungent heath (Leucopogon Fraseri) ; but the frequency of any species differs greatly in different localities and under' different conditions in the same locality. .

CERTAIN GRASSLAND PROBLEMS.

There is problem after problem awaiting solution in order to prepare a path for advance in improving the montane grassland. The following

are some, out of the many, problems which are being attacked, and .they may serve to give some idea of what is meant by the title of this article, “ An Economic Investigation of the Montane Tussock-grassland of New Zealand.’A" ■

(a.) Botanical Names of Plants.

A few lines back certain species were cited under their botanical names.. These names are those of science, and one might confidently anticipate. that they would represent definite unchangeable entities . of the plant-world, for science is supposed to be exact. But such. a belief would lead to great confusion ; indeed, for economic purposes certain of these .botanical names are highly . misleading.. In fact,. they do not refer to groups of similar individuals which reproduce their like from Seed, but to mixtures of such groups, although possibly each group of the mixture is quite distinct from all the other groups of which this is made up in regard to its soil-requirements, its palatability,* and its other characters of fundamental economic importance. Such composite, species which are ideas only and do not exist in nature are termed aggregate species. They are a botanical convenience only in the earlystages of investigation of a flora. To look upon such names as final would be equivalent to abandoning the agricultural names of cultivated plants, and, using , a concrete example, to clump together swedes of all kinds, soft turnips of .all kinds, and garden turnips of all kinds under the comprehensive name “ turnip/'. Needless, to say, a field sown, with such a mixture would be a .remarkable sight, as the crop developed.

It is clear, then, that the actual segregation of the various races of palatable grasses and other herbs of the tussock-grassland, and the giving to such unnamed races definite names, is an important preliminary to economic advance. This study is being prosecuted not only by the aid of specimens living and dried and field observations, but by cultivating numbers of plants of the same aggregate species side by side in different gardens— i.e., under differeht environments.

(&.) Relative Palatability of the Various Species.

With regard to the .palatability of the various species of the montane tussock-grassland very little is known. Two sheep-farmers, both men of the greatest experience, expressed to me totally divergent views as to the value of Chewings fescue, the one asserting that sheep hardly touch it, and the other that it. was a valuable feed. Even regarding the actual feeding-value : of the fescue-tussock and the silver-tussock nothing definite is known. The blue tussock (Poa Colensoi) has been asserted again and again to be highly palatable, yet there is considerable evidence come to hand that it is rarely eaten. In short, most that has been recorded regarding the palatability of the indigenous grasses and herbs is. mere guesswork. On the other-hand, a purely scientific study of the high-mountain plant-associations has shown that the greater part of the tussock-grassland species are not eaten at all. Unfortunately,, many of these are able to spread so rapidly by means of certain of their vegetative parts (underground or creeping stems, for example) that when the balance of nature is disturbed by fire, or the palatable species are

kept in bounds, through 'grazing, these non-p able' plants increase their area of occupation by leaps and bounds and become true noxious weeds. Thus wide breadths of the grassland become for pasture purposes just as barren as if no plants were —more barren, indeed, than most parts of the depleted area of Central Otago. The following are some of these indigenous induced, weeds : The red piripiri (Acaena micvophylla), the spineless piripiri (Acaena inermis), the turf-coprosma oprosma Petr, the mat-raoulia (Raoulia subsericed), the mountain-twitch . (Triodia exigua), the • swamp-lily {Chrysobactron Hookeri), and, above all, the pungent heath (Leucopogon Fraseri). Coming now to actual measurement of palatability, an experiment is to be carried out at Hanmer Springs this month in order to ascertain the relative palatability of certain plants both indigenous and introduced. A paddock of 25 acres is fenced in with rabbit-proof fencing. Its plantcovering, consisting of 100-species or so, available for sheep, has been noted. Labels,' 270 in number, have been fixed here and there telling what species are in their-vicinity. Five hundred sheep are to be turned on to this area, and the plants they feed on are to be carefully noted. Early in.the first day the most palatable are expected to be chosen, and' so on until at the end of perhaps a week only those species will be getting eaten which, under ordinary circumstances, would not be eaten at all. By means of experiments of this nature and by extended observations' in the field it should eventually be possible to assign to each species a number denoting its palatability. Then, when the composition of the' plant-covering of a tussock-area is accurately estimated, so that the amount of ground occupied by each species is approximately known, it should be feasible to give such a combination of plants a number which would denote its value as a wool-producing crop, and thus various areas could be compared in this regard. But for- such a distinct advance the time is still distant. •

The sheep-runs of the Waimakariri River basin (Canterbury) offer an exceptional advantage for observing what sheep eat, because in that area the rabbit has never become a pest; indeed, rabbits are so few as to be negligible.

(c.) The Question of Burning the Tussock.

Even in the earliest days of sheep-farming it was found that the fescue-tussock and the silver-tussock were but little relished by sheep, but that, on being burnt, green, leaves upon which sheep could feed were put forth in abundance. Burning, then, has taken place yearly in some part or other of most montane sheep-runs since the “fifties ” and “ sixties ” of the last century. Generally speaking, such burning has been indiscriminate, with the consequence that acres and acres of tussock-grassland have been turned into stony debris ; 'that indigenous weeds, as described above, have replaced wide areas of more , or less palatable grassland ; that the subalpine shingle-slips have increased in size ; that forest and shrublandboth valuable for shelter purposes—have disappeared ; and, finally, that the depredations of the rabbit have become intensified. ....

It should not be a difficult matter, by aid of observations and experiment, to study the actual effects of burning, and to arrive at a better understanding as to how, when, and where burning should be carried out. Even at this early stage of the montane grassland investigation,

but bearing in mind the observations of many years, it may confidently be asserted that indiscriminate burning is a dangerous practice, even when carried out at what is considered the best time—the month of August or thereabouts.' There appear to be definite cases in which burning is indefensible. Some of such cases are the following: (i) Where the tussocks are obviously weakly and small; (2) on stony slopes readily turned into shingle-slip ; (3) in the subalpine or alpine belts ; (4) in the neighbourhood of rabbit-warrens ; (5) where there is a chance of greatly increasing an unpalatable plant, especially, the swamp-lily {Chrysobactron Hookeri*). ' ' ' ' - .

(d.) The Rabbit Question.

That a sheep-run may be rendered valueless by “ overstocking ” with rabbits need not be emphasized. Nevertheless there is much to be learnt regarding the control of the rabbit and the relation of this pest to high-mountain sheep-farming. That so much of Central Otago is “ depleted ” is not altogether the effect of the rabbit. There has been indiscriminate burning and more or less overstocking with sheep. But the climate is the driest in New Zealand, and this to no small extent is also responsible for the state of affairs in Central Otago.

In parts of the Upper Awatere Valley (Marlborough) the progress of damage by the rabbit may readily be studied. On the rather loose side of gentle slopes where there are thickets of the wild-irishirianf {Discaria toumatou) are many rabbit-warrens, where every stage of grassland destruction may be observed. Taking the case of a piece of ground closely occupied by tussocks, the bare earth stands out conspicuously dotted with rabbit-holes and surrounded by - a wall of tussocks, which in many places, owing probably to the heavy manuring they undergo, are more or less moribund, especially where bare ground and tussock meet. The first stage of depletion by no means-removes all the vegetation, but the primitive tussock-association is replaced by somewhat the following combination of species : Sorrel {Rwmex Acetoselld) in great abundance, and forming the groundwork' of the new induced association ; the small rosettes of the mountain cranesbill {Geranium sessiliflorum var. alabrum) dotted here and there, a remnant of the primitive plant-covering not eaten even by rabbits ; the paleleaved ■ willowherb {Epilobium novae-zealandiae), a slender, small, semiprostrate herb, also not eaten ; sage-green, more or less circular mats of the mountain piripiri {Acaena sanguisorbae var. pilosa) ; brown, flat, circular mats of the spineless piripiri. {Acaena inermis) ;■ the small, grasslike sedge Carex breviculmis ; some Scotch thistle {Carduus lanceolatus) ; chickweed {Stellaria media) ; and the larger mouse-ear {Cerastiwm triviale). The three last-named species and the sorrel are introduced plants, the remainder are indigenous. The oldest part of the infested ground is distinguished by the rabbit's unmistakable trade-mark the great circular, silvery or green, dense, low cushions of the scabweed {Raoulia lutescens), between which, especially -where exposed to the wind, there may be no other plants. . Where no depletion is taking

place the scabweed is confined to river-bed or other stony ground, but when the tussock and most of .its accompanying plants are removed there is bare ground for the germination of its wind-borne “ seeds.”

(&.) The, Distribution of Danthonia.

If it were possible for danthonia (Danthonia pilosa in one or other of its unnamed varieties) to become established in sufficient quantity on the montane tussock-grassland, then the carrying-capacity of the pasture would be greatly increased. The exact altitudinal distribution of danthonia is not at present known. From my observations in October last I found that it reaches to somewhat over 2,000 ft. in the Awatere Valley (Marlborough). Experiment and. observations are urgently demanded in the following directions : (1) To find out the exact altitudinal range of danthonia at the present time in various mountain areas ; ' (2) to sow and plant danthonia at various altitudes under different conditions ; (3) to separate from the complex mixture of races known collectively as Danthonia pilosa one or more races (varieties) which are hardy and capable of holding their own in the montane tussock-grassland.

(f.) Surface-sowing

Surface-sowing on the montane tussock-grassland is practised but little at the present time, but formerly it was carried out to a considerable extent. Seed was scattered here and there on various parts of the run, but, so far as I am aware,, the results were not satisfactory. The causes .of failure were, in part, the use of unsuitable species, such as rye-grass (Lolium perenne} ; sowing at the wrong time of the year ; and, especially, using seed of an extremely poor quality, anything being considered good enough. Above all as a cause of failure is the fact that the hard soil is altogether unfavourable for the' germination of . seeds. Thus it seems necessary to find out accurately how seeds of different species of edible plants behave with regard to germination under different conditions of the surface soil. Seeds of various grasses and other plants will therefore be sown in small patches on a piece of montane tussockgrassland enclosed for the purpose. The physical condition of the surface soil, upon which the seeds are sown will be carefully noted, and the various seed-beds will be chosen so as to differ greatly in this regard, just as the actual grassland where sheep graze offers a considerable diversity of stations for the germination of seeds. Then, it is also proposed to carry out a number of surface-sowings on the ordinary pasture, using as the seed-bed burnt tussock, unburnt tussock, ground with the surface slightly broken up, stony river-flat, and so on. Seed-mixtures for this purpose have been designed and carefully prepared by • the Biologist of the Department. As this matter of surface-sowing develops it. will be dealt with in future articles. The Waimakariri sheep-runs with their almost entire absence of rabbits offer'special advantages for these experiments. ■ z

(g.) Cultivation.

. A certain amount of cultivation is carried out on the land in the vicinity of the homesteads of most sheep-stations. . This is usually for the purpose of providing chaff for the working-horses. .Usually no pro vision "is' made for ' furnishing winter feed, but for such’ the

sheep are dependent on that supplied by the winter country” —i.e., certain slopes facing the sun or the lowest parts of the run. It is important to find out exactly what cultivation is being carried out at different stations, and especially at. what altitudes paddocks of permanent grasses such as cocksfoot (Dactylis glomerata) have been established. This most valuable grass is now growing on certain mountain- sheep-runs as if it were indigenous. In the valleys, for instance, between Molesworth and Tarndale, drained by the Acheron and its tributaries, in many places splendid cocksfoot grows naturally, and also white clover (Trifolium opens) is in astonishing abundance. This area is reached by a good deal of western rain, so the foregoing is no criterion as to the behaviour of cocksfoot and white clover elsewhere.

At Molesworth itself, where the climate is drier, at an altitude of about 2,800 ft., there is a good paddock of cocksfoot which has been established for more than ten years.' I . saw it only in the middle of October after an exceptionally late winter, and at that time the grass formed rather dense cushions between which were patches of ground occupied by sorrel. ' . .

At a height of 2,200 ft., more or less, at Castle Hill Station (Canterbury), Mr. J. Millikin grows most excellent cocksfoot. He also grows yearly, at the same altitude, 100 acres of Green Globe turnips on which sheep are fed, and 100 acres of oats for hay. Lucerne (Medicago sativa) is virtually neglected by the back-country sheep-farmer, but many intend to put in a little as an experiment. . As .lowland Marlborough is the great centre for lucerne-growing, its cultivation, as might be expected, is extending into the mountain-valleys. Thus, Mr. W. Stevenson showed me at Upcot (Awatere Valley), at an altitude of about 1,800 ft., some excellent lucerne, and there is a small area at an altitude of about 2,200 ft. in the orchard at Langridge farther up the valley. Speaking of the mountain-valleys generally, there are many river-flats, at an altitude of 1,500 ft. and upwards which look well suited for the growing of lucerne, and experiments as to their capabilities in that direction are urgently demanded. _ At . present the excessive cost of fencing prohibits anything being done on a large scale, but quite modest experiments could demonstrate the feasibility or the contrary of lucerne-cultivation.

Small Sheep-dipping Plant. Several inquiries have been received as to the quantities of concrete required for the bath and draining-floor of the one-man sheep-handling plant described and illustrated in the Journal for June last and reprinted as Bulletin No. 75. The quantities are as follows : —Dipping-bath: Concrete for walls and floor, 5|in. thick = 21 cubic yards; cement plaster for surface of same, 15 square yards? Dripping-floor: Concrete, 4 in. thick = 2 cubic yards; cement plaster on surface of same = 16 square yards. Concrete to be composed of 6 parts clean gravel, 2 parts clean sand, and 1 part cement. Plaster to be composed of 2 parts clean sand and' 1 part cement. '■

* Dr. Cockayne was recently appointed by the Department to conduct an economic investigation of our montane tussock-grassland, and has now carried out a good deal of preliminary work. The present is the first of a series of articles on the subject which he will contribute to the Journal. — -Editor.

* In most dictionaries this word is not given, but in its place is “ palatableness.” The Oxford Dictionary, however, gives both words, and I chose “ palatability ” because it is much more easily pronounced.

* Acres and acres on many sheep-runs are now occupied and rendered useless by this pretty but economically worthless plant. J To some better known as “ Matagowrie,” a corruption of the Maori tumatukuru.

Note. —In this article and investigation the term “grassland” is used in its plant-geographical sense, and does not refer to land on which the grass grows,' but to the plant-covering alone, which consists principally of grasses. .