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In our first issue we made a general statement of the policy to be followed. The reception to Volume 1 has given encouragement for continuing and extending that policy. For the benefit of new readers, it may be easiest to explain this in action more specifically by reference to the contents of this issue. Firstly an account of work at the Cawthron Institute is given. Although its name is well known, there are many people who are not aware of the scope of subjects being investigated there, and the outline by its director, Sir
Different aspects of field biological studies are presented in the two succeeding articles. The study of the conversion of rain forest to grassland is one of special significance in this country which is so dependent on grasslands for its economy. The method of approach to a problem of plant ecology by Mr. Levy may be new to students who have confined their attentions to the study of “unmodified” associations. They will find that the inclusion of man's activities as a major modifying and controlling agency, gives some very interesting data and comparisons which closely link agriculaure with the study of the plant successions in vegetation unmodified by man. The account of a zoological field problem by Mr. Allen is of particular interest, as the popular interest of an animal usually increases as its numbers decline. In the essay on the grayling, a discussion of the possible reasons for the spectacular decline in numbers of this once abundant fish, will provide material for consideration by all interested in the problems of declining populations.
As in previous issues, keys for the identification of an animal and a plant group have ben given. The need for these in this country where so much descriptive work on species is still required, is so obvious that it does not require elaboration.
To some of our readers the contents of “Tuatara” may seem to be rather solid fare for a journal which is aiming to present general accounts of biological work. We feel, however, that it is better to retain the details necessary to support general statements, and readers may then be able to draw further conclusions from their own interpretations of the facts. In particular, it is hoped that teachers may find the contents in a form which can be readily used and expanded for class teaching.
The Cawthron Institute owes its origin to the munificence of Thomas Cawthron, who left practically the whole of his fortune, valued at $250,000, for the establishment and conduct of a scientific institute and museum.
The original trustees, appointed under the will of Thomas Cawthron, decided, on the recommendation of a Scientific Advisory Committee, that the major activity of the Institute should be research in the interests of New Zealand agriculture with reference to problems of both farmers and orchardists. The proposals of the Trustees were approved by the Supreme Court and early in 1920 the nucleus staff under the Directorship of Professor (now Sir Thomas) Easterfield was appointed and work was commenced.
Three main departments of scientific research were established in 1920 and these were maintained with but little change until the close of 1941 when a Biochemical Department was formed to handle more effectively plant and animal nutritional problems. The principal work of the four scientific departments is connected with (a) soil and general agricultural problems; (b) plant chemistry and mineral deficiency problems of stock; (c) insect problems of farm, orchard, and timber, and the biological control of noxious weeds; (d) fungus disease problems of fruit, hops, tobacco, and market garden crops. A technical museum, having special reference to the primary industries of Nelson and the natural history section of museum work, forms an integral part of the Institute and provides suitable facilities for the presentation of the work of the research departments to the general public.
Since the inception of the Institute seven additional bequests of a total value of some $50,000 have been received. In addition, the work of the Institute has been assisted from time to time by grants from the Empire Marketing Board, local bodies, and the primary producers of New Zealand. In recent years the Minister of Scientific and Industrial Research has given increased financial assistance for soil, mineral deficiency, tobacco, fruit, and entomological investigations of the Institute.
In several branches of research work, the staff of the Cawthron Institute collaborate with officers of the Department of Scientific and Industrial research. Entomological, tobacco and hop research, at Nelson, are conducted on a co-operative basis, both Cawthron and Government officers sharing in the research programme.
The Nelson district in which the Cawthron Institute is located has a climate which favours horticulture, and it is in this branch of agriculture that very marked development has taken place in recent years. The whole of the tobacco and hop industries of New Zealand are located in the Nelson district. In addition, Nelson has a very important section of the apple industry together with considerable acreages of small fruits, tomates, and market garden crops.
Arable farming, dairying, and sheep farming are all represented in the agriculture of Nelson, and at different times problems connected with these branches of agriculture in addition to horticultural crops have been investigated by the Institute.
One of the interesting features of the Nelson district is its diverse geology. Ultra-basic rocks of serpentine, basic rocks of melaphyre,
Although the work of the Cawthron Institute is not confined to the Nelson district, a great deal of its work is associated with the soils and special crops of Nelson. The work of the entomological department at the Cawthron Institute, however, has a more general application to agriculture outside the Nelson district in that the parasitic control of insect pests and the biological control of weeds, as a rule, apply in equal measure to agriculture throughout the whole of New Zealand.
In several aspects of both soil and insect research the Cawthron Institute has gained special distinction for the initiation and development of work of major importance to New Zealand agriculture. This is particularly true in connexion with the work carried out by the Institute in soil surveys, trace element deficiency, the parasitic control of insect pests, and the biological control of noxious weeds.
One of the important investigations commenced in the inaugural year of the Cawthron Institute was a reconnaissance soil survey of Waimea County, Nelson. This survey constituted the first systematic soil survey conducted in New Zealand which gave due recognition to the important part placed by both geological origin and texture in soil properties. Although modern methods of soil classification have necessarily entailed a revision of the soil groups identified in these early surveys, the units set out on the soil maps have required little alteration and have proved invaluable in the conduct of investigations relating to animal health, plant nutrition, and the manuring of crops.
Among the soils of the Waimea County which have proved of special interest to Nelson, and indeed to the whole of New Zealand, may be mentioned Moutere loams and Kaiteriteri loams. The Moutere soils have furnished spectacular deficiencies of lime, phosphate, nitrogen, potash, boron, and magnesium, several of which have seriously limited both yield and quality of crops—particularly of apples grown on these soils.
The Kaiteriteri group, derived from granite, has proved of no less interest in view of its association with marked deficiencies of cobalt, boron, and magnesium. In no part of New Zealand are the
The success achieved by the Institute in soil survey work in Nelson led to the establishment of a Soil Survey Division by the Department of Scientific and Industrial Research and the initiation of a reconnaissance survey of the volcanic ash soils of the central North Island territory of New Zealand. The Cawthron Institute was intimately associated with this and other surveys which were carried out in Taranaki, the Waikato, North Auckland, Hawke's Bay, and other parts of New Zealand. The reconnaissance survey of the volcanic ash soils proved of very great value as some of the soils were associated with stock ailment. When, as a result of other investigations, the cause of “bushsickness” was identified as cobalt deficiency, the survey of the volcanic ash soils made possible the immediate application of this discovery to practically the whole of the affected country in the North Island.
In more recent years soil survey work at the Institute has been concentrated on the detailed mapping of the alluvial soils of Nelson for the expansion of the tobacco industry. The results of the survey show that the Waimea County has some 10,000 acres of soil texturally suitable for the culture of flue-zured tobacco. Tobacco soil maps prepared from the soil examinations are proving of great value in the sound expansion of the tobacco industry.
The Cawthron Institute has played an important part in the identification of trace element deficiency affecting both animals and plants in different parts of New Zealand. The investigations of the Institute have comprised studies of cobalt deficiency on the granite soils of Nelson Province and on the loess soils of Southland; boron deficiency on two soil types in the Nelson district and on several soils in Central Otago, and magnesium deficiency of apples and tobacco on the granite and Moutere Hills soils of Nelson.
In regard to cobalt deficiency, studies of “bush-sickness” in sheep on the granite soils of Glenhope were commenced in 1928, and of lamb ailment in Southland in 1934. Evidence was slowly accumulated which ruled out a theory of iron deficiency as the cause of these stock ailments and suggested another element which was contained in certain iron ores and soil “licks” which had proved beneficial in the treatment of stock ailment.
Aided by the announcement from Australia that cobalt was an element of nutritional importance to stock, chemists at the Institute quickly showed that cobalt overcame stock ailments at Glenhope and Southland, and that there was an actual deficiency of cobalt in the soils, pastures, and organs of affected animals. The work carried out
As a result of the investigations carried out by the Department of Agriculture in the North Island and by the Cawthron Institute in the South Island, it can be said that cobalt deficiency on New Zealand has been overcome; the production of fat lambs and successful dairying has become possible over hundreds of thousands of acres which were formerly seriously affected by stock ailment or under suspicion.
Similar work has been carried out by the Institute in regard to the incidence of boron deficiency in apples, apricots, plums, and grapes on certain fruit soils in Nelson and Central Otago. Surveys of the boron content of soils and fruit have been carried out in all fruitgrowing districts of New Zealand and methods for overcoming boron deficiency have been studied. The investigations have shown that boron deficiency in fruit trees can be controlled by the use of half a pound of borax per tree or by the use of borax sprays at 0.1 per cent. strength. One of the interesting features of the experiments on apples was the adverse effect on keeping quality when borax was used in excessive amount.
More recently, studies of fruit trees in the Nelson district have shown the presence of magnesium deficiency on the Moutere Hills type of soil. Premature defoliation of trees had been noticed in certain apple manurial experiments of the Institute. Injection of different elements into the limbs of affected trees showed that magnesium salts were highly beneficial in controlling defoliation. Analyses of the leaves of affected trees showed a high deficiency of magnesium. The identification of magnesium deficiency in apples under commercial conditions of culture was of considerable interest. The Nelson work paralleled similar investigations carried out by Long Ashton workers and suggested the possibility of a fairly common occurrence of magnesium deficiency in horticultural crops on soils naturally low in bases, particularly where excessive amounts of potassic manures have been used. An interesting feature of the Nelson experiments on the control of magnesium deficiency in apples trees has been the success achieved with ground dolomite in restoring affected trees. This magnesium compound used at the rate of twelve pounds per tree has given more permanent benefit than the use of the corresponding quantity of magnesium sulphate.
Orchardists in New Zealand will always remember the spectacular success achieved by the Cawthron Institute through the introduction of Aphelinus mali parasite for the control of woolly aphis which, for
The parasite, obtained through Dr. Howard, United States of America, established freely in New Zealand and very quickly brought about a great reduction in woolly aphis, thereby saving many thousands of pounds in the cost of oil sprays.
Similar work has been carried out by the Institute in the introduction of the parasite, Habrclepis dalmani, for the control of Golden Oak Scale. Liberations of the parasite were made at Nelson, Christchurch, and New Plymouth. In every case the parasite was an outstanding success and gave an effective control of Golden Oak Scale.
A more recent introduction by the entomologists at the Institute has been that of Rhyssa persuasoria, for the control of the horntail borer which attacks pine plantations. The parasite has been liberated at several centres in the South Island of New Zealand and has multiplied rapidly. There is every indication that the parasite will prove valuable in the control of the horntail borer.
Although several insects have been introduced with a view to the control of noxious weeds in New Zealand, success has been somewhat limited. The Cinnabar moth and the ragwort seed fly were both introduced for the control of ragwort but so far have not been successful under field conditions in the control of this weed.
The Chilean saw-fly was likewise introduced in an attempt to control piri-piri, but although quite effective under laboratory conditions, this insect, so far, has not been successful under field conditions.
The gorse seed weevil, Apion ulicis, however, has established freely at all points where liberations have been made. Examinations of gorse pods show that the weevil is exerting a marked effect on gorse seed production and should eventually be an important factor in controlling the spread of the plant.
The recent introduction of the European beetle, Chrysolina hypersizi, for the control of St. John's Wort appears to be an outstanding success and is proving very effective in the control of this noxious weed in the Awatere Valley, Marlborough.
The establishment of the Entomology Division of the Department of Scientific and Industrial Research at the Cawthron Institute under the direction of Dr. D. Miller, Chief Entomologist to the Institute, has greatly strengthened entomological research at the Institute. The work carried out by the Government entomologists on the parasitic control of the White Butterfly and the Diamond-back Moth has been very successful and has resul ed in immense savings to farmers throughout New Zealand.
The horticultural crops of Nelson provide great scope for Cawthron mycologists. Their services have been in constant demand by orchardists, tobacco growers, and market gardeners, for the identification of diseases and for advice concerning their control.
Outstanding work has been done by the mycologists in the study of “Black-spot” of apples, “Brown-rot” of stone fruit, diseases of small fruits and tomatoes. In recent years very detailed studies have been made of tobacco mosaic and the factors which operate in its dissemination in the tobacco gardens. The importance of the seedling bed stage in mosaic transmission has been established and the necessity for the greatest care in handling plants to avoid infection has been stressed. Several tobacco diseases, new to the Nelson district, have been identified by the mycologists. Among these may be mentioned “Angular leaf spot,” “Verticillium Wilt” and “Black Root-rot.” The early identification of diseases and the application of suitable control measures have been of great importance in the successful development of horticulture in the Nelson district.
In this brief review of the work of the Institute it has been possible to describe only the more important activities of the Intitute. During the twenty-nine years of work at Nelson a great variety of work has been successfully handled and no less than 470 scientific papers have been published by members of the staff.
The success of the Institute has not depended solely on the results achieved by research. Of almost equal importance has been the great influence exerted by the Institute on farmers and citizens throughout New Zealand, in creating an appreciation of the value of scientific research.
The editorial committee has much pleasure in acknowledging the financial assistance given by the Wellington branch of the federation of University Women for the publication of the plate accompanying Dr. Allan's article. Assistance in the cost of printing this number of “Tuatara” was given from the Publications Fund of Victoria University College.
Owing to the greatly increased demand for the Journal three numbers will be published in 1949 in March, June and September. The subscription rate is 3/3 posted. Thank you for your support of the Journal. We regret that copies of Vol. I Nos. 1 and 2 are no longer available.
Although one may not subscribe to Kelvin's belief that our knowledge of a subject is meagre and unsatisfactory until one can measure what one is speaking about and express it in numbers, I believe it would be generally agreed that the introduction of quantitative methods into biology has led to significant advances.
Foremost among these methods has undoubtedly been statistical method; indeed, it was the needs of biology which gave the stimulus for the development of a large part of the recent advances in statistical theory. In this connection the names of Francis Galton, Karl Pearson, William Gosset (who wrote under the pseudonym of Student) and R. A. Fisher, should be familiar to all biologists.
Statistical method provides procedures for handling numerical data which are subject to uncontrolled variation. Examples of such data are to be found in any scientific investigation where measurements are made. The use of a collection of measurements on selected characteristics, e.g., beak, wing, leg and tail lengths of birds from different areas, as an aid to classification of the group into sub-species or races, is a case of some interest. If one takes the measurements of the birds of one species in a restricted area, the results will differ from bird to bird and there will certainly be a greater range of variation in the observations obtained from the examination of birds from a larger area, or from widely separated localities. The results will differ, although they may overlap to a certain extent, but due to basic variability there will be uncertainty whether the differences are due merely to the differences to be expected in sampling from one species, or whether they indicate a real difference between the groups examined.
An excellent example of a study of this problem for an ocean sea bird is set out in “The Life Cycle of Wilson's Petrel,” by Brian Roberts (1940). His analysis for birds collected from widely dispersed regions in the Southern ocean, has shown that there are four distinct subspecific races separable by measurements. The importance of the result obtained by this method is stressed because many past separations into races in birds, and in many other animal and plant groups has been done arbitrarily or from insufficient data, and can be shown to be invalid when subjected to statistical analysis.
Even in the best controlled and most precise experimentation, as for example in the physical determination of the velocity of light, uncontrolled variability is smaller than one would find, say, in the weights of grain in harvesting a field of wheat by small sections. But the difference is one of degree rather than one of kind. As a concrete
Such an array is called a frequency distribution. It records the number of times each type of observation concerned occurs.
The type of variation shown here appears very frequently in biological observations. The most common observation (11 in the table) is somewhere near the middle of the whole range and the number of observations decreases steadily on each side of this.
Let us consider a few of the problems which arise in the handling of material of this nature. First there arises the question of further reducing the results and summarizing them in a few numbers which convey the salient features of the distribution. We require first a typical measure of the number of germinations per plate. The usual quantity employed for this is the arithmetic mean of the observations. For the table above the mean number of beans germinating on a plate is 11.2. The mean is an abstraction—there is no plate having this number of germinations—but it does give a measure of the general level of germination for this batch of material.
We next require some measure of the variation shown by the results. The simplest one is that known as the range, and this is the difference between the largest and smallest observations, here 16 minus 6 equals 10. One grave weakness of this is that it is based on limited number only of the observations and so it does not take account of the manner in which the numbers are distributed between the extremes. The most commonly used measure, and one derived from all the observations, is called the standard deviation. (This name should be regarded as a technical term, for there is nothing particularly standard in the ordinary sense about it). To calculate it we determine the difference between each observation and the mean, square this difference, sum all the squares so formed and then divide by the total number of observations, thus obtaining the mean square. Finally, in order to obtain a measure in the same units as the quantity observed, viz., number of beans, we take the square root of this mean square. The result is the standard deviation (s.d.). For the data it is 1.7. In a general way one can see that the number so obtained is a kind of average of the deviations of the observations from their mean and so it gives us a measure of the amount of variation in the material. It is found that these two numbers, the mean
The next problem requiring consideration is the implication of the inherent variability for experimental investigations with the material. Suppose from the 183 sets of 20 beans we choose, by some random procedure, 25 sets, then we obtain the following germination counts: 10, 14, 6, 11, 7, 11, 11, 8, 7, 14, 14, 10, 10, 10, 9, 9, 10, 12, 12, 8, 13, 8, 10, 12, 14. giving a mean 10.4 and a s.d. 2.3. A second set is 14, 10, 9, 9, 14, 12, 10, 7, 11, 12, 10, 12, 14, 10, 8, 11, 11, 10, 13, 7, 11, 13, 14, 8, 7, having a mean 10.7 and a s.d. 2.2. We see that these two samples have means and s.d.'s different, but not greatly so, from the original 183 sets, that is, the inherent variability of the material involves differences in the numerical characteristics of samples from it.
The original group of 183 sets of 20 is itself a sample from the whole bulk (population is the term commonly used) of beans from which they were chosen. Its numerical characteristics reflect those of the bulk but undoubtedly differ from it to a greater or lesser extent. In carrying out the above experiment the experimenter presumably was interested in the behaviour of the whole bulk. How good an estimate of the germination rate of the bulk is the 11.2? If we find that it is not accurate enough for the purpose in hand, how can we improve it? One way that suggests itself intuitively is to take more observations. Can we determine how many so that we can achieve a prescribed degree of accuracy? Statistical method gives us answers to queries like these, admittedly under definite assumptions about our material and the way that we handle it, but assumptions that are adequately fulfilled in many cases of practical interest.
Suppose now that we wished to compare the germination rate of beans from two different sources of supply. We could take one set of 20 from each and determine the germination rate. Let us assume the results are 10 and 15. Judging by the variation shown in the distribution given earlier these could be from the same bulk. But they could equally well be from bulks having different germination
In carrying out such a procedure we are performing what is called a test of statistical significance. Briefly the argument involved in all such tests is as follows. We make the hypothesis that the two lots of experimental material have the same germination rate (the “null hypothesis”), i.e., we regard our results as coming from the same bulk, then the calculations of the test give us a measure of the chance of obtaining, on the uniformity hypothesis, the difference actually observed. If this chance is moderate, e.g., 1 in 5, then we would assert that there is no difference in the rates for the two sources since the observed difference is one that could arise frequently (viz., 1 in 5 times) from uniform material. But if on the other hand the chance is small, e.g., 1 in 50, then we would probably rule that the uniformity hypothesis is false, in other words, the sources do differ in germination rate.
It may be noted that the application of tests of significance is greatly facilitated in most of the cases that arise by the fact that table are available which give the value of the relevant chances, after quite simple arithmetical calculations.
Since the outcome of the test of significance is expressed in the form of a chance it should be clear that there is no hard and fast dividing line between situations where we decide to accept or reject the null hypothesis. This decision requires considerations of a non-statistical nature, such as for example the economic consequences of taking one course of action or the other. It is, however, the convention in most biological work to adopt a chance of 1 in 20 (the 5 per cent. level of significance) as the critical point. This implies that we are prepared to take the risk once in 20 times of making a wrong decision regarding our hypothesis.
In addition to the replication requirement introduced above, there is a further one implied in the mathematical theory on which the test of significance is based. This is that the sample from each bulk be truly representative of that bulk. One way of achieving this is to take a random sample. Most people have an intuitive notion of what is meant by randomness, although it is a difficult idea to define. It is
A very useful development of statistical method is that which provides for the analysis of data in which each observation consists of more than one number. An illustration is afforded by investigations arising from herd-testing work among dairy cattle. For a group of cows we can obtain for each cow her butter-fat production as a two-year-old and her “maturity equivalent” production, this being defined as the average of the 4, 5, 6 and 7 year productions. Thus we have two production figures for each animal. We find, as might be expected that a knowledge of the 2-year production gives some indication of the maturity equivalent. For a certain group of 702 Jersey cows the maturity equivalent production ranged from 141 to 560 . butterfat, but those with a 2-year production in the interval 261-280, the maturity equivalent production lay between 231 and 470 . There was a similar narrowing of the range over all the 2-year groups.
Such pairs of observations are said to be correlated and there is a large part of statistical method concerned with the reduction and analysis of this type of data. One very important concept used is the idea of the regression line which originated in the statistical work of Francis Galton. If we calculate for the above data the mean maturity equivalent corresponding to the successive 2-year production values and plot results on graph paper, we find that the series of points suggests a definite curve, in this case a straight line. A mathematical expression can be set up for this line and this expression is called the regression line of the maturity equivalent production on the 2-year production. The idea of the regression line is of very wide applicability. One use to which it can be put in the present case is to give us a means of estimating what, on the average, any one cow's mature equivalent production will be, given her 2-year production. Providing our sample is representative we can use the formula to give us such an estimate for new batches of 2-year olds.
The ideas and methods worked out for data involving pairs of correlated observations have been extended, in the theory of multiple correlation and regression, to cover situations where we have three or more observations made on each individual.
In conclusion I wish to make some general remarks on the use and place of statistical method. It is but one of the aids available in the analysis of biological data and must not be allowed to obscure the fact that the primary interest of the investigation is biological. In
There are numerous American textbooks written for the biologists and of very varying quality. Two good ones are Statistical methods by G. W. Snedecor and Methods of statistical analysis by C.
Crustaceous lichens are abundant in New Zealand both in species and individuals. They occur on rocks from sea-level to the upper limits of plant life. They are also plentiful on bark and soil, while one family is confined to the surface of leaves. Opinions differ greatly concerning the limits of families, genera and species, and for detailed knowledge intensive microscopic work is required. It is not impossible, however, to gain a good general knowledge of families and many genera by fairly simple observational methods. For ecological purposes this general knowledge is not to be despised as hitherto lichens have been sorely neglected in studies of vegetation. A difficulty is that there remain probably many hundreds of species yet to be collected and identified. Several overseas specialists are anxious to obtain specimens from New Zealand of their particular groups and a student desiring to make any special study would do well to get into touch with one of these workers. The numbers of the figures attached to this note follow on from those of the previous note in “Tuatara,” Vol. 1, No. 3.
STRIGULACEAE.—Two genera of this family are known in New Zealand on the leaves of tawa, titoki, ramarama, Asplenium and a few other trees and shrubs. Strigula has a more or less orbicular yellowish thallus, and Phylloporina a more irregular greyish thallus.
VERRUCARIACEAE.—Verrucaria is the genus most commonly met with in New Zealand. The species are most prevalent on coastal rocks, the thin dark thallus closely investing the rock-surface.
PYRENULACEAE.—Mostly bark-inhabiting species with several genera represented here. A species of Arthopyrenia forms tiny dark spots on sessile barnacles. There are several species of Pyrenula not easily distinguished in the field.
CALICIACEAE.—The stalked fruits of Calicium look like minute pins stuck on the thallus. The family has not been much studied in New Zealand.
CYPHELIACEAE.—A species of Cyphelium with a greyish thallus and uniseptate brown spores occurs on rock in tussock-grassland.
ARTHONIACEAE.—A few bark-inhabiting species of Arthothelium with muriform spores have been recorded. A. vermiferum forms small greyish flecks on the leaves of Metrosideros colensoi and other species.
GRAPHIDACEAE.—The family is widely distributed here, but has been little studied. The genera found are keyed.
LECIDEACEAE.—A very large family with many genera and a multitude of species. Zahlbruckner lists over sixty species of Lecidea for New Zealand, others have been recorded and described, and probably many more await discovery.
Catillaria is well represented, but the species are difficult to distinguish by simple characters. A few species of Megalospora have been recorded; M. marginiflexa is widely distributed on the bark of trees. Bacidia occurs on rock and bark, both coastally and inland. One species has been recorded from leaves of podocarps.
Toninia belongs to this family, but has a corticate, warted squamulose thallus. One species occurs on limestone. Lopadium—The several species of this genus recorded for New Zealand occur on leaves. L. coerulescens has a wide range of hosts, including Asplenium. Rhizocarpon has several species, of which R. geographicum with a greenishyellow thallus is widespread on rocks. It is striking on account of the more or less “map-like” arrangement on the rock surface.
THELOTREMACEAE.—We have a few species of Thelotrema with muriform spores. Surrounding the proper margin of the apothecium is an overarching thalline margin.
LECANACTIDACEAE.—The species of this family, related to the Graphidaceae, have a thin thallus. The proper margin of Lecanactis is quite prominent.
PERTUSARIACEAE.—The apothecia are immersed in thalline warts and the spores are simple. In Perforaria the apothecium has a small pore-like opening; P. cucurbitula is widely distributed and occurs on bark, rock, dead vegetation, moss and soil. We have about forty species of Pertusaria, in which the apothecia have a wide opening.
BUELLIACEAE.—Members of the family superficially resemble Lecideaceae, but the spores are brown and two-celled. We have a number of species of Buellia, mainly on rock. We have also several species of Rinodina, distinguished by the thalline margin to the apothecium.
LECANORACEAE.—A large family, well represented in New Zealand.
CALOPLACACEAE.—Two genera are represented: Blastenia, the apothecia lacking a thalline margin; Caloplaca, the apothecia with a distinct thalline margin. The former is poorly represented, but we have some twenty species of Caloplaca, the small apothecia often light yellow or red.
In a land where there were no native mammals, fish were a very important source of food to the Maori before the coming of the white man, and the Maori became very skilled in their capture, both in the sea and in the fresh-water lakes and rivers. Although some fish, particularly the larger species, were caught with hooks and lines, the Maori depended to a large extent on the use of nets and traps of which he developed many ingenious forms. Among the fish, then abundant, which he caught in the rivers in this way was one generally called the Upokororo, although like most animals known to the Maori it had a number of other names, either peculiar to certain tribes or denoting particular phases in its life history. This fish entered the rivers at certain seasons of the year in large shoals, and was found in many parts of the country. One of the most usual ways of taking it was by setting basket-work traps in the rapids with their mouths upstream and with two walls of boulders arranged in a V to divert the current and any fish moving downstream into the trap which was fixed at the apex of the V. When the trap was set it was sometimes left overnight, so that fish moving out on to the rapids from the pools to feed were swept into it and caught. On other occasions the fish were driven out of the pools upstream by men armed with long poles, and, fleeing downstream with the current, were carried headlong into the trap. That other and possibly more original methods were sometimes used is suggested by an early writer on New Zealand who says of the grayling: “It bites at the hairs of the legs and is thus caught by the natives going into the water.” Unfortunately, it is not quite clear whether the fish took firm hold and the natives then walked out towing the fish!
When the white man arrived he found the graylng both widespread and abundant, although it was some time before it attracted the notice of scientists. Apparently, however, it received the English name of “grayling” at an early date, presumably on account of its superficial resemblance to the European species of that name in its slender shape, silvery scales and the possession of an adipose fin, although it lacked the very large dorsal fin which is such a characteristic feature ot the true graylings. In 1869 some specimens were sent to Frank Buckland, who passed them on to Dr. Gunther at the British Museum. In the following year Gunther described them, naming the species Prototroctes oxyrhynchus, and referring it to the family Haplochitonidae; a family which is related to the northern trouts and whitefish but which has a southern hemisphere distribution.
At this time the species was still abundant and Hector in 1871 says that it was “found in most of the streams of the colony,” and goes on to speak of the “immense shoals” ascending the
Thus it seems clear that this fish, which was apparently abundant throughout many parts of New Zealand when the Pakeha first arrived, and which remained abundant until at least 1870, declined rapidly in numbers, until fifty years later it was confined to a few isolated parts of the country, and has since continued to decline, so that no known stocks now remain. The accompanying map shows the districts from which it has been reliably recorded; the shaded areas being the approximate drainage basins of the rivers in which it is known to have occurred, while the black circles represent localities from which the species has been reported since 1920. The appearance of the map together with a number of less precise reports suggest that the distribution on the west coasts of both islands was probably much more continuous than is indicated, but it seems likely that it may have been relatively scarce on the eastern coasts. There appears to be a fairly close degree of correspondence between the known distribution of the grayling and the areas which were originally covered in forest.
The causes of this disappearance form an interesting subject for speculation, but unfortunately at this late date it cannot be very much more. There seem to be three most likely causes to consider if we assume, as appears justifiable, that it has resulted from some activity of the white settlers. These are—that man has taken sufficient direct toll of the species to cause its disappearance: that he has, by some means such as the clearing of bush from the water-sheds, so altered the habitat that the fish can no longer survive: or that the introduction of the trout has somehow destroyed the grayling. Of these, the first seems most unlikely; there is little evidence of the grayling being subjected to fishing for the market except in a few cases, and with the coming of the trout few anglers would be interested in it, although earlier on it was fished for in some places. Also, it seems to have disappeared even from streams in sparsely settled districts where any intensive fishing would be most improbable. The widespread clearing of the bush and other agricultural practices have undoubtedly seriously affected many rivers, generally causing an increase in the extent of the shifting shingle of the beds and more violent floods and droughts. These factors are generally adverse to most species of fish and could conceivably have been particularly adverse to the grayling. However, the species seems to have disappeared not only from waters affected in this way but also from others, particularly in Westland, where the bush covering of the water-shed has not been touched.
It seems then that neither of the above possibilities is likely to have been the cause of the disappearance of the grayling, and serious consideration must be given to the third possibility—that the grayling has been unable to survive in the presence of trout. There is some evidence that supports this possibility. In one of the few cases where a date can be put to the decline of the grayling—the Maitai River in Nelson—we find that it began to be scarce about 1874, and trout were first introduced into this river in 1870 and were apparently successfully established. It is also noticeable that some of the waters in which grayling are known to have been present at a relatively late date, the Waiapu River near East Cape, the Turanganui near Featherston, and the Wahapo River in Westland, are all waters where trout are present only in small numbers. On the other hand, grayling are said to have disappeared from the Waikato about 1874 (the same year that saw the beginning of the decline in the Maitai) although trout were not established there until at least ten years later. There are also many waters in New Zealand which do not contain trout, and from all of these the grayling is now absent. This absence may of course be due to the unsuitability of these streams to grayling as well as trout, but if they were ever present the introduction of trout cannot have caused the disappearance.
Thus none of the suggested explanations seems to cover the facts fully, and the true cause of the disappearance of the grayling must remain a mystery. The apparently simultaneous disappearance in waters as diverse as the Maitai and the Waikato tempts one to consider an epidemic as a possible cause, but there is no other evidence supporting this and on general grounds it seems most unlikely. The whole position is made still more obscure by the lack of reliable information regarding the life history of the fish. It apparently ascended the rivers in large shoals, composed of fish between 5 and 12 inches in length. These shoals after their ascent rested in the bottoms of the deep pools by day and were believed to come out on to the rapids, to feed upon filamentous algae and other growths encrusting the stones, at night. It is said that their presence could be detected by their teeth-marks on the stones when feeding in this way. After remaining in the rivers for some time they disappeared, although no definite downward migration seems to have been observed. The ascending fish were heavy with spawn, but no observation of their spawning habits has been recorded, nor has the presence of the young stages. It seems most likely that the ascending fish were coming up from the sea, but even this is not definitely established. There are some discrepancies between the various accounts as to the time of year in which it was in the rivers, but most of them seem to accord with the following outline. The movement into the rivers began about early or mid-summer, and from then until about March or later the fish were slowly moving upstream. In late autumn and early winter they were in the upper reaches of the rivers and if this was a spawning migration spawning probably actually took place at this time. In late winter and early spring they disappeared, perhaps returning to the sea. When first entering the rivers they were silvery in colour, slightly brown on the back, but appear to have gradually become darker, being finally rich brown on the back and yellow beneath.
The little that is known of its life history thus gives no clue to the causes of its disappearance, but there still remains the possibility that the study of a surviving stock, if one exists, would not only reveal the life history of this interesting species, but also explain why it vanished under the impact of European civilization. At present, however, we do not even know whether it is indeed extinct, or whether, like the now-famous takahe, it still survives in some unfrequented spots.
K. R. ALLEN, Fisheries Laboratory, Wingfield Street, Wellington.
The native Grayling: as explained elsewhere in this issue the history and biology of this fish is somewhat mysterious, and it is not even known whether it still exists. Any records of its occurrence during the past twenty years, or specimens or notes of locality, number, size and season would be very welcome to Mr. Allen. The only fish with which it may be confused are the trout and salmon and the native “smelt” or “silvery.” It may be distinguished from the former by the generally smaller size (5-12′) and absence of spots, and from the latter by the larger size (the smelt is generally 2-5”), absence of a bluish stripe along the flanks and relatively forward position of the first dorsal fin which in the smelt is approximately above the vent. In no other fish is there a second dorsal fin reduced to a fatty protruberance.
Metamorphosis—alteration, often of a profound nature—occurs in the life-cycle of all but directly developing amphibians. The New Zealand frog Liopelma has a direct development, but most other frogs, and the newts and salamanders, undergo more or less metamorphosis in the transition from larval to adult forms. External change is obvious to anyone who has watched, even casually, a developing frog: the development of external gills and their later loss; growth of limbs; absorption of the tail; the straightening and shortening of the tightly coiled, larval intestine, and the growth of the adult jaws follow each other in orderly sequence. Among newts and salamanders, fundamental changes, although not so apparent as in the frogs, nevertheless do occur—external gills and tail fins are reduced and absorbed and adult colour markings are assumed.
There are, however, internal changes at metamorphosis no less profound, but less observed and certainly less understood, than those occurring externally. One of these changes, probably unrecorded until Major S. S. Flower in 1927 noted its occurrence in the European Spotted Salamander, is a complete loss of memory which coincides with the metamorphosis. Such loss of memory indicates change in the nervous system of this salamander at metamorphosis. Major Flower kept three newly-born salamanders in separate jars. By giving individual attention, all three soon became tame enough to show no fear when approached, would take proffered food, and after some weeks, would even call attention to themselves when hungry by active movements and sending out bubbles. As metamorphosis approached, appetites increased, and the animals would freely swim to his hand and take earthworms.
Metamorphosis is complete, Flower says, when the larval gills disappear. This occurred on different days for each of the three salamanders. Although the environmental conditions were quite unchanged, all memory of their human attendant was lost in each case on the day of metamorphosis. Close approach to the jars frightened the animals; they tried to avoid capture by the hand and struggled wildly if picked up, they would not feed. A process of re-taming, taking several weeks, had to be undertaken, as though they were freshly-caught wild animals.
Flower's work points to an interesting and little known aspect of the metamorphosis of amphibians, an aspect that might well repay further study.
The New Zealand crabs have had a stormy systematic history. Even today there is no complete convenient account available describing these common and interesting animals which are such an important element in our marine fauna. This guide is not a final statement of the systematics of these animals. It is only a step in bringing this part of this fauna within the reach of students and cannot as yet be carried to completion because much literature is unavailable. It has been developed from my personal needs and is presented here as an aid and stimulus to the researches which are yet to be undertaken. I will be very grateful for any corrections, alterations or additions which can be suggested. Many species of our crabs are poorly known, some only from a brief account of the one original specimen and the status of others, even of common species (e.g. Ozius truncatus) is still in doubt. Species are included in the guide which are doubtfully part of our fauna. These species are bracketed and noted here to enable their recognition if actually present.
This is a guide to our crabs of the families Portunidae, Cancridae, Xanthidae, Grapsidae, Ocypodidae and Pinnotheridae, which are Brachrhyncha—crabs in the ordinary sense, lacking a rostrum, having a round to squarish body, the mouth located in a square to oblong area (the mouth-field), covered by the mouth-parts of which the third maxillipeds are the external elements. These Brachyrhyncha contrast with the spider-crabs and masking-crabs which also have an oblong mouth-field, but in these the carapace is commonly triangular in outline with the apex anterior so that these crabs are grouped as the Oxyrhyncha. Because of the common oblong form of the mouth-field, crabs and spider-crabs are grouped together as Brachygnatha. In this respect they contrast with another common group of crabs, the Oxystomata, in which are included the ball-shaped crabs, the box-crabs, and the flat-back crabs—varying much in shape but having in common a narrow, elongate and rather triangular mouth-field.
Several portunid crabs not listed in the key have been recorded from New Zealand. In particular species having 9 antero-lateral spines should be watched for and reported if found. There appear to be only the two species of cancrid crab; the xanthid crab fauna is richer but very inadequately known and much further research is required. I have handled two additional distinct species, neither identifiable with the species listed in the key. The grapsid and ocypodid crabs are reasonably in order but the pinnotherid crabs are in need of extensive
P. pisum, a European species has been identified in New Zealand material by at least two specialists, one of whom considered our dwarf Portunus as the northern hemisphere Portunus corrugatus. Local students may find the opportunity for important work in the description and revision of Xanthidae and Pinnotheridae.
The key is drawn from many sources, but its content is largely determined by Chilton and Bennett's review of the Brachyura (Trans. N.Z. Inst., v. 59, 1928) which clears the fauna of some species, establishes the nomenclature for others, and gives a ready entry into the literature on this subject. Rathbun's monographs (U.S. Nat. Mus., Bulls. 97, 129, 152, 166) are invaluable as a reference and guide in many problems, and will be found most useful for further detail required in advanced studies.
The figures are restricted to an outline of the carapace and it must be noted that to enable presentation of all these species in two plates, the figures are drawn to much the same size. The figures are not drawn to scale which would have been well-nigh impossible for this guide since the species illustrated range in width from one half inch to four inches and a half. An indication of the width of each species is given in the key. For much the same reason, the ornamentation of the surface of the carapace is commonly omitted. The figures are useful only in conjunction with the key. Each illustration shows the fronto-orbital width (between the lateral orbital spines, marked by the outer pair of arrows), the contour of the front (between the orbits, between the medial pair of arrows), and the antero-lateral and postero-lateral margins of the right side. Excepting where noted in the key, the spines at the orbital angles are included in the count of the antero-lateral spines, and frontal spines respectively.
The keys are set out as far as possible on a natural systematic basis, so that confusion between the species included and others is unlikely. The features selected are generally readily observable, but difficulty will be found in the case of the Xanthidae. The important ridges which are mentioned in 1 (4) can only be seen by turning the mouth-parts well down. If present, the ridges may be low, rounded and not very conspicuous; if absent, the plate anterior to the mouth will be quite smooth, as for example in Ovalipes. The reference numbers, e.g., Key to Families, 1(6), are alternatives. Where there is not agreement with 1, then refer to 6. Where the agreement is with 6, then proceed to 7, etc. This type of key is advantageous in that the summary of the features fitting the specimen give the essential points in the generic and familial definitions. Also, the method permits a ready return through the key when errors have been made, or when the review of the features dealt with is desired.
(NOTE: The free-living Hymenosomidae, for long included in this Family, are dealt with later as Oxyrhyncha. These are small flat-backed crabs of the genera Hymenicus, Halicarcinus, Hymenosoma and Elamena.)
Carapace swollen, obese, globular, second joint of external maxillipeds small or lacking G. Pinnotheres.
New Zealand has, in round figures, 18,000,000 acres of sown grassland, of which 12,000,000 acres have replaced forest, 4,000,000 acres have replaced tussock, and 2,000,000 acres have replaced fern and scrub.
Of the area of forest felled and sown to grass some 10,000,000 acres have been more or less successfully converted to grassland, the remaining 2,000,000 acres reverting to secondary growth. Some 2,000,000 acres are still in natural fern and scrub and some 3,000,000 acres of standing forest await development or are on country too steep to develop.
The total grain, green fodder and root crops occupy approximately 1,000,000 acres with plantations, orchards, market gardens, private grounds and fallow a further 1,000,000 acres making in all some 20,000,000 acres effectively occupied and farmed. To this must be added some 14,000,000 acres of Montane tussock country which is range grazed in large holdings.
The original forests may be classified into two main ecological types: (1) Rain forest, (2) Subantarctic Beech forest. In the latter southern beech (Nothofagus) is dominant. The rain forest is divisible into associations in which either broad-leaved trees or coniferous trees (Podocarps) predominate. Many such associations are developmental; tawa (Beilschmiedia Tawa) would appear the climax dominant in rain forest, while rimu ( Dacrydium cupressinum), rata (
Tussock grassland, bracken fern (Pteridium), heath and scrub associations precede forest. Of these associations, the following genera characterize the development in ascending order from bare ground
Raoulia, Festuca tussock, Poa tussock, Discaria, Danthonia tussock, Carmichaelia, Muehlenbeckia, Pimelea, Dracophillum, Styphelia, Pteridium (stunted), Pomaderris, Olearia, Cassinia, Leptospermum, Pteridium (strong), Coriaria, Hebe, Griselinia, Coprosma, Brachyglottis, Rapanea, Pseudopanax, Pittosporum, Myrtus, Nothopanax, Dicksonia, Cyathea, Schefflera, Fuchsia, Edwardsia, Pennantia, Melicytus, Aristotelia, Hoheria. In the swamps Typha, Phormium and Cordyline usually precede the podocarps, Dacrydium Colensoi, D. intermedium and Podocarpus dacrydioides. In nature, complete climax dominance seldom occurs, owing to disruptive factors such as fire, earthquake, volcanic action, land-slides and gales breaking the forest cover, whence an initial surface for forest development occurs. Indigenous induced and exotic induced associations are common in New Zealand.
The forests are felled by axe during the winter and early spring on a contract system, the men feeding themselves and housing themselves in a tent or whare. The price of felling average forest, leaving all trees above 30 inches in diameter standing, was approximately $2 per acre. The cost of felling today would be $4 to $5 per acre. Under-scrubbing precedes the felling of the larger timber; the success of the burn depends upon the thoroughness with which this operation is carried out. Next, the forest trees up to approximately 30 inches in diameter are felled by a system of driving, the trees being notched on the upper and lower side of the drive, which is commenced at the top of the slope downwards. A good drive lessens considerably the cost and toil of felling. In very wet climates the bigger trees are left standing on the supposition that these occupy less space standing upright than if they are felled.
In a normal season, early in January, the owner anxiously watches the weather conditions and, given a dry spell of approximately two weeks, makes preparations for the burn. If distant from the homestead, he and his team may camp on the spot to await a favourable steady wind, blowing away from the uncut forest. Successful grassing of the country depends upon the success of the burn, more particularly in areas of high rainfall. A steady, hot fire if possible is desired to burn all fallen timber, leaf mould, seeds and fern spores lying dormant on the forest floor. A white ash, called a white burn, is the objective: a black burn results from a skimming fire where the heat is not sufficiently intense to burn the timber, leaf mould, seeds and spores on the forest floor.
Given a favourable wind the fire is lighted on as long a face as possible and happy is the man who sees a solid wall of fire sweeping
After the burn a telegram confirms the order for seed which may be already on hand, particularly if the season is late. When the burn is made in early summer a sowing only of soft turnips may be made, the grass seed being sown later among the turnips or when these are being fed off in the autumn. A good crop of turnips will in large measure pay the cost of felling the forest and grassing the burn. From grassing trials with and without soft turnips on a primary burn, there would appear to be no detriment to the final sward through including the turnips in the mixture, or in making a sowing of turnips prior to the grass seed.
The seed is taken to the burn and distributed at convenient spots, working across the slope and from the top downwards. The seeding is made broadcast by hand, one sower following another at a cast distance further down the slope. The seed is carried in a sowing bag on the shoulders and across the back and is so slung that the seed falls to the right and left side of the bag in which openings are made convenient to the hands. On easy country both hands are used for sowing, but on steep country one hand is usually fully engaged clinging to stumps or logs while the free hand sows.
The seeds mixture varies considerably and is dependent in large measure on the class of forest felled and on rainfall. After some considerable experimentation on primary forest burns in the belt with 50 inches and over of rainfall, the following seeds mixture has been devised:
Burns may be differentially sown. The spurs, ridges and poorer aspects being sown with one seeds mixture, the better flats and easier slopes with another. In the former case Brown top (Agrostis tenuis) may be increased to 2-3 lb. per acre and Chewing's fescue (Festuca rubra var. fallax) 3 lb. added, whereas on the fertile areas these grasses together with Danthonia pilosa, may be eliminated or considerably
Phleum pratense), alsike (Trifolium hybridum), and red clover (Trifolium pratense) added.
The cost of seeding a primary burn was from thirty to thirty-five shillings per acre but present day costs are between $3 and $4 per acre.
As soon as possible after sowing, the burn is ring-fenced and later subdivided. Fencing is a considerable item and is expensive, particularly where heavy timber has to be cleared from the fence line and where much shelving has to be done on steep, arete ridges. Fences are erected along the main ridges and down leading spurs, and erection across slopes studiously avoided for fear of slips. Wherever possible sunny country is fenced off from shady country to facilitate control of stocking. Fencing is usually done on a contract basis. Totara posts are used for the most part. A fence consists of four posts to the chain, seven plain galvanized No. 8 wires with three or four battens betwen each post. The cost of such a fence, including erection, was approximately $2 per chain, but today costs are up to $6 a chain for material and erection.
Stocking the new burn takes place about eight weeks after sowing, both sheep and cattle being employed. In areas where much timber remains unburnt, tracking of the burn to enable stock freely to graze all parts of the burn is necessary, for the ability of stock to graze and tread the burn in large measure predetermines whether the succession is to grass or back to forest. The proportion of sheep to cattle varies according to the nature of feed and class of country. One cattle beasts to 5-7 sheep is necessary wherever the danger of secondary growth is real. Where the country is comparatively easy to hold, one cattle beast to 10-15 sheep is a fairly reliable figure as practised, but the number of cattle to sheep could with advantage be increased.
Ecologically, the stock factor in subsequent developments is of paramount importance. The sown grasses in themselves are powerless against the myriads of seedlings and sporelings of shrubs and ferns that arise once the forest shade is removed. It is a struggle often for many years against these growths, and success or failure of the grassland sward depends on the number of stock that are maintained on the area to eat off and tread out fern and scrub growth and thus to maintain the ecological balance in favour of grass rather than forest. Stock, secondary fires, the slash-hook or grubber are all ecological agents that work towards this end.
Of the deforested country in New Zealand today, some 2,000,000 acres have carried insufficient stock to maintain the grass versus forest balance and regeneration back to forest is proceeding apace.
The class of stock and stock manipulation may entirely alter the ecological conditions both for the early precursors of forest and for grass. There may arise induced associations entirely different from the sown grass sward and from the association of fern and secondary forest trees that would arise if these were unchecked by stock after the primary burn. Thus, under a system of close and continuous grazing by sheep we may see either a swing over to hardy, low-producing, light-loving grasses or to unpalatable fern, scrub and weedy growths according to the ecological conditions set up. If these latter growths predominate, all stock will ultimately be forced off the area and succession to secondary forest and ultimately to primary forest proceeds.
The most common stock-induced associations on the deforested areas are (1) manuka ( Leptospermum scoparium), hard fern (
The grass swards on deforested hill country vary considerably in botanical composition, depending on the fertility of the soil (whether natural or induced artificially), by the class of stock, and the method of stocking. In the best swards, perennial ryegrass ( Lolium perenne), cocksfoot (
The control of secondary growth is a feature of almost all deforested hill country. The process consists in firing the growth while
The seeds mixtures in these secondary scrub, fern or logging-up burns are important. Much deforested hill country went repeatedly back to secondary growth until suitable seed mixtures were devised from carefully conducted experiments. The introduction of Browntop (Agrostis tenuis) and Lotus major to wet hill country has in many instances turned failure to success. The following seeds mixture has been found the most suitable for virtually all the wetter secondary hill country:
In the Auckland Province 2 lb. per acre of Paspalum dilatatum may me added with advantage. On the drier areas of the East Coast, the
It can be fairly safely reckoned that a settler succeeds or fails according to the maintenance costs of his country and whether he has ready cash to meet those maintenance costs as they arise. The burn must be well grassed and well fenced, and cattle must be acquired even though the direct profits from these are often exceedingly low. To stock deforested hill country entirely with sheep leads to disaster. Much of the poorer hill country reverts to manuka ( Leptospermum scoparium) which must be either pulled or cut. Neglect leads to an
Finance, labour, topdressing, overseeding, fencing, the intelligent use of fences; the appropriate class of stock and the grazing management of that stock, i.e., rotational mob grazing, rather than sparse, set stocking—together with the will to win of the farmer, and often of the farmer's wife, are fundamental to the success of forest conversion to grass.
The grazing management is extremely important and without exception sheep and cattle are employed. In certain districts gorse and blackberry are prevalent and goats may also be used. The cattle are really the hill country implement for consolidation and crushing out undesirable secondary growth and to act as the mower to clean up roughage in the autumn and winter to give young and succulent growth for the ewe and lamb in the spring and for the hoggets in the winter. Set stocking with sheep and cattle may be practised, but a system of rotational grazing where it can be adopted is definitely
Summing up, the really successful man of the hill country is the cattle man and the cattle-sheep man where the grazing is of the rotate, mob-graze type. The cattle to sheep ratio is held important and this varies from 1 to 4 or 5 up to 1 to 10 or even lighter. The actual ratio is probably less important than the grazing management. Set stock, whatever the ratio, is less likely to succeed than rotate mob grazing be it either with all cattle or all sheep or with a high or low cattle to sheep ratio.
The despoilers of the hills is the hard set sheep grazier and the man who attempts to dairy on the small limited flats and easy foothills adjacent to or subtending the hill country itself. The indifferent absentee holder and speculator are a menace to the hills: so too are the unoccupied Crown Lands and much Maori held land. A vigorous occupancy is the keynote and it behoves the State to encourage occupancy with provision of all-weather access roads, with schools and social amenities to help and inspire youth to put his or her heart into the work and into the hill country. The hill country is and always will be a young man's country and deterioration must set in anew following on old age. Adequacy of reward for the hills is essential to enable old age to retire from the hills once failing strength is no longer competent for the task of farming that country.
The surge of secondary growth coincides with periods of depressed prices for farm produce and with labour scarcity such as in time of war. The World War I took many hill country men as did also World War II, and although the latter has been over for 3 years the return of young men to the hills is lamentably slow owing largely to more remunerative jobs offering in built up areas of population, together with the disinclination of the State to foster rehabilitation of difficult
Certain of the more isolated secondary growth areas may yet have to wait a further generation of young men before the surge forward into this class of country is undertaken. In the meantime secondary growth will dominate and what grassland has survived will be obliterated by such growth, until new blood takes the country up again with renewed vigour. Within these deteriorated areas there is, however, a tendency for much country to be farmed with the firestick to open up periodically the secondary growth sufficiently to allow some stocking of the area and while there is some merit in this type of farming its unsystematic approach will never win the country to grass although each burn sets back the forest regenerative processes and allows some light into the sward to encourage its development.
It is impossible to say with accuracy the acreage of deforested country in New Zealand that has been stumped, ploughed, and resown, but the area now is considerable and is increasing each year.
After the forest has been felled, secondary scrub and logging-up burns proceed until only standing stumps remain. These are ultimately removed by burning out, by haulage or by blasting, operations which are usually postponed for upwards of 20 years after the burn, by which time decay has set in and removal is comparatively easy. Of recent years the bulldozer has ben successfully employed in clearing, stumping and logging up deforested country. Secondary log fires may be on a grand scale and the speed with which fire spreads in a dry season among the fallen and standing timber is amazing. Fanned by a strong wind, log fires may spread over thousands of acres in a few hours and the writer has experience of such a fire so darkening the sky that artificial light had to be used well into the morning over 100 miles distant from the scene of the fire. Such a fire has dreaded consequences within the immediate area concerned, and stock, hay stacks, outbuildings and homesteads usually suffer. However, incalculable good is done in so far as clearing the country of much rubbish is concerned.
A great deal of hill country, even when cleared of logs and stumps, is unploughable, but one of the outstanding features of development of hill country is the steepness of much of the country that is being turned over by the plough. This is possible by the strategic use of ploughing on the contours and by the use of hillside ploughs and
Ploughing, or giant discing the hills wherever possible, is again, an individual-farmer characteristic. One man will plough where another will claim it is utterly impracticable to plough, just as one will topdress with seed and manure where others claim topdressing is out of the question; one will use and work cattle where another will say cattle losses are too great: one will pull or cut manuka and other scrub, will burn and sow at every available opportunity while the other will be dilitant and lose golden opportunities to clear the country: one will erect fences and will use those fences to the full in controlled rotate-mob-grazing, another will try to do without fences and will not use intelligently the fences he has. Such individual characteristics make or break the more difficult hill country.
The seed mixtures for these hillside sowings are important. May be the area will never be ploughed again in the lifetime of the present owner and failure to get a good sward at this time will mar the whole future of that country. Here, as in all grassland development, success or failure rests on the number of animals that can be maintained and adequately fed on the established sward. This ploughed hill land, properly sown and given a good start with ample and even liberal manuring during their early establishment phases, will carry four or five sheep per acre, plus some cattle, and this carrying capacity, where it can be maintained, will just simply make the country and will keep the sward growing for all time with a normal yearly or two-yearly application of phosphate to keep the clovers going strongly.
Ploughing hillsides not only destroys weeds and secondary growth, but it definitely tends to level the country and to eliminate innumerable hillocks and small hollows that can never produce as well as the more even sward. Whereas now the hillocks are carrying mainly moss, poor type grasses and flat weeds (largely because these hillocks never get trodden upon or urinated upon by stock) the levelling off of these and the filling of hollows institutes a uniform growing condition and gives a greater chance for stock to tread over and urinate upon the sward.
This is true not only of the hills but also of the flat and undulating country. Ploughing enables the country to be levelled and advantage should be taken of every period when the plough goes in to level that country as much as possible to bear on the job during the cultivation, even to bringing in bulldozers or road-graders. Every flat or undulating farm taken out of forest should be equipped with a good levelling board.
Nonetheless on the hills stock will tend to track and contour the hillsides and the ultimate fate of well stocked country will be a series of broad or narrow terraces with steep slopes between upon which stock seldom tread. From a soil conservation point of view maybe this stock-terracing could be expedited and guided by the running of coun our furrows along the hillsides, but however the terracing is done, there will tend to arise two fairly distinct ecological associations on the hills—one, dominated by grasses where the stock tread and urinate, and one on the steep slopes betwen the terraces dominated by clovers and lower-fertility demanding grasses. The more stock we can carry the broader and more numerous will these terraces become. There will also be a considerable expansion in the size and area of stock camps, which too, will be dominated by the better grasses and clovers just so long as those camps are not too closely confined to small ridges, lone trees, etc., where too great a concentration of treading leads to bare ground in the summer and to annual weeds in the winter and spring. The avoidance of these over-used camps by a grazing management designed to rotate the stock more and possibly by the strategic space planting of many more trees in any one paddock is one of the problems of the hills. Perhaps it is permissible too, to speculate upon the ultimate relationship of the terraces and camps to the steep slopes between the terraces. These steep slopes, if more liberally fertilised with phosphate than the terraces and camps can be made to grow clover in abundance. That feed, when consumed, supplies from the dung and urine of the animal the all essential nitrogen to keep the grasses of the terraces, camps and uniformly grazed slopes up to high productivity and hence to raise the carrying capacity of the country as a whole.
Of recent years on the more level deforested country, stumping and ploughing, and much reploughing, has been expedited by the use of bulldozers and by the introduction of certified strains of grass and clover seeds and by a fuller realization of the values of artificial manures, particularly when used on a sward constituted of herbage strains that are capable of giving high returns. The following seeds mixtures have more recently been devised and are recommended on a ploughed and prepared seed bed:
For the ploughed steeper slopes some of the more sward-binding grasses are advised and the following mixture is recommended:
For the drier areas Subterranean clover 2 lb. per acre should replace the Lotus major. In the North Island (Auckland Province) Paspalum dilatatum 4-6 lb. per acre may replace the Cocksfoot.
Practically the whole of the deforested hill country was felled and sown prior to the setting up of pasture plant improvement work and the marketing of these improved strains under certification as to strain or type. In the early days of conversion also the thesis was expounded that only the best English grasses should be sown on the hills. It was considered doubtful in many cases whether the sowing of Cocksfoot was even justified, so great was the growth and so good the early promise on the ash of the forest burn. On the other hand there was much seed, undressed and even cleanings that went into the so called cheap mixtures for rough bush-burn country.
Since the decline of soil fertility, experience has definitely shown that lower fertility demanding species are imperative and of these Browntops, Lotus major, Danthonia and Subterranean clover have demonstrated their value.
Today also there is a marked tendency for hill country to be top-dressed with phosphate, and for this practice to be made the most of, good strains of clover in particular, should be introduced into the sward simultaneously with the topdressing. As stock-carrying increases, so will the set up encourage perennial ryegrass and crested dogstail. There has been in the past very much country sown with poor ryegrass strains which have largely run out. It looks, therefore, as though it is imperative to oversow the majority of our hills with seed to ensure the best possible opportunity for deriving the greatest advantages from phosphatic topdressing and build-up of stock nitrogen that will result as the stock carrying capacity of the country is increased.
For surface sowing the following seeds mixture is recommended:
Other species may yet find a place in this over-sowing seed formula after the trials now under way have been going for a few years.
Topdressing with phosphate is the key to hill country improvement and towards its full development, and every artifice, financial, mechanical, political and industrial self-help known to man should be brought to bear to put a 2 cwt. per acre per annum dusting of phosphate on to the hills.
Hand topdressing with various devices to spread and to get the phosphate on to the hills are at present being employed. The pack horse for carrying, and bull-dozers for making tracks greatly relieve the tedium of hand spreading. Mechanical blowers may be of very great assistance but one feels the heavy load lifting aircraft will ultimately be the answer and already developmental work is in progress to explore the possibilities of developing this aid to the hills.
Rain forest in New Zealand is convertible to grassland and there is a distinct correlation between the original forest cover and the grassland species that will thrive once the forest is removed. The climate that makes possible the development of rain forest is a grassland climate and it is not difficult with the aid of stock and/or fire and agricultural implements to maintain a bias in favour of grassland rather than forest. The maintenance of soil fertility at an appropriate level for high grassland production, together with strict adherence to sound principles in pasture establishment and utilization, tend to increase the stability of grassland and to make more and more remote the possibility of reversion to forest.
Progress meanwhile is far from stationary on the greater part of our hills. In the course of some 80 years a great cattle and sheep industry, store and fat stock and wool, has been built up and a forest wilderness converted to pasture. In that development the pioneer had no previous experience to guide him. He knew nothing of the processes whereby forest regenerated itself, or of the forces at work in that regeneration: he did not know that the fight could be economically won only by the use of cheap fire-stick methods and by the correct use of appropriate grazing animals: he did not realise the insidious spread of secondary growth weeds, bracken fern, hard fern, water fern, manuka, bid-a-bid, etc., under the close and continuous nibbling of the turf by sheep: he was ignorant of the correct grasses and clovers and was misled by the strong and early growth of the coarse grasses that weakened and opened up as the spurious fertility of the bush burn declined: he did not know that the part the correct sward played in the competitive struggle against the return of the forest. Nevertheless large areas went successfully to grassland: vast areas went partially to grass, part o secondary growth and part to young forest, the decline to such growths being governed mainlv by the nature of the turf and according to the accessibility of various aspects of the country to the grazing animal.
It is difficult to assess the part the working sheep and cattle dogs and the hunter pig dog, have played in the winning of forest to grass and in the keeping down of wild life that deprecated the flocks. Were it not for the inevitable dog and the horse it is safe to say the forest
We may now look back and be tempted to decry as sacrilege the forest destruction as a national waste, but to the pioneer the forest stood between starvation and a livelihood in the crops and grass that could be established only on its reduction to ashes. It was a menace to be removed as cheaply and as quickly as possible. Millions of feet of timber that today would be a valuable asset went up in smoke, but for 80 years and more that deforested country has grown grass, has reared stock, has produced its annual crop of wool and stores for the lowlands to fatten; it has given livelihood to the pioneer and his grown family and their families and has contributed a main portion to our national wealth. This has built a society and given rise to cities, towns, prosperous trades, professions and industries that at the moment can offer better wages, better social facilities, better amenities in the home, better houses, etc., to the detriment of its own cause and its own existence. That country leans hard today on a handful of stalwarts, still a band of pioneers, but in an age when pioneering is more difficult and is apt to be scoffed at and adjudged the quality of the loon by its more invertebrate critics of the easy lowlands and comfortable environs of the city.
Let us make no mistake about it. If this spirit of the pioneer is killed a nation loses some hing of inestimable value and beyond replacement. It may be killed unless there is encouragement by the State and by every able-minded person who has the vision to see and to appreciate wherein the nucleus stamina of the race abides. The open, broad hill country has built a race, is still building and maintaining that race but its numbers are too few for the good of the hills to get from them their undoubted greater latent wealth. The area of our hill country could be extended by millions of acres and the per acre production could be doubled, trebled or quadrupled and at the same time the future of the hills greatly vouchsafed for the generations to come if we had the labour force and wherewithal to put into operation the knowledge in grassing, in manuring and in management that we now possess.
Biology for Australian Students. W. M. Curtis, M.Sc. (Lecturer in Botany, University of Tasmania.)
A well written text catering particularly for Australian conditions although New Zealand teachers and students will find much of the contents suitable for post-primary instruction. The book covers the main parts of the syllabuses in biology for the Matriculation Examination in Tasmania and Leaving Certificate Examinations in New South Wales and Victoria. Details of practical experiments pertinent to each chapter are given. A useful appendix covers dissection instructions for the Rabbit, the Vascular system of the Frog, the Ventral arterial system of the Dogfish, etc., as well as some formulae for culture media and the better known reagents. Aust. and N.Z. retail price 10/6.