BY THOMAS T. C. BIRCH
Recognition of the importance of organized forestry in New Zealand culminated in 1920 when a new Department - the State Forest Service - was formed and given statutory and administrative authority by the Forests Act, 1921-22. The initial recommendations of the first Director of Forestry included the statement that "the formation of a strong research division is absolutely necessary if we are to make any advance in the solution of the forest problems of New Zealand." Unfortunately action on this recommendation was deferred and, with a few marked exceptions, forestry research in the Dominion during the last 28 years can only be described as sporadic; the chief reasons for this were the inadequacy of trained staff, financial stringencies of a world depression, and the inevitable disruptions of a world war. Despite these handicaps, the quality and quantity of research accomplished cannot be regarded as unsatisfactory.
The pioneering work of Dr. Leonard Cockayne on the botany and ecology of the indigenous forests was of the highest quality and remains the basis upon which subsequent indigenous research has developed. Throughout the early years of its development the Forest Service has established many experimental plots of diverse character in both exotic and indigenous forests, while in more recent years fundamental research has been carried out on seed crops, viability of seed, and growth cycles of commercial species. In the field of forest utilization, much applied research has been undertaken and the results have already been incorporated in everyday wood-using technique and practices. The development of national grading rules for building timbers and the wide adoption of kiln-drying schedules are examples of outstanding results from applied research.
For 20 years the Forest Service operated on a broad organizational basis, with its small staff concentrated chiefly upon administrative reforms and practices in indigenous timber sales, and upon large-scale exotic forest establishment. Administration was, as now, decentralized in the seven Conservancies representing major territorial charges, but neither in these nor in the central office of the Director of Forestry was sufficient specialization developed to warrant a more detailed organization.
With the appointment of a number of qualified forest officers in 1939/40 it became possible to plan for the development of work on a divisional basis, but this reorganization was delayed until 1946 when five basic divisions were established. At that time the coordination and control of staff recruitment, training, and research, were vested in the new Development Division.
As a direct result of this reorganization, provisions were made to place research on a permanent basis, and in 1947 a Forest Experiment Station was established in Rotorua. Still very youthful and in process of expansion and consolidation, this national Experiment Station has, nevertheless, been well founded and is at present actively engaged in initiating and co-ordinating many short-term research projects, and in developing a long-term research policy. The present nucleus staff includes nine professional officers; but the immediate establishment provides for three times this number, and steps are being taken to obtain the additional staff in the early future.
The objective of the Experiment Station is to initiate, supervise, and co-ordinate all forest research work carried out in the Forest Service. Its activities are based on the principle of close co-operation with the staffs of the Conservancies which are expected to make local investigations under the indirect supervision of the Experiment Station. The Station is subdivided into four branches, Botany and Silviculture, Management, Pathology, and Forest Products, under the direction of an officer-in-charge, who is linked administratively with the Development Division, the headquarters of which are at the office of the Director of Forestry in Wellington.
The National Forest Survey
Initiated a year before the establishment of the Experiment Station, but now a function of that organization, the National Forest Survey is the most outstanding current investigation. The main objectives of this Survey are:
(1) To estimate the volume of available merchantable timber in the remaining non-protection indigenous forests, the estimate to be by major regions, and within each region by species and diameter classes.(2) To revise existing national estimates in order to obtain more accurate figures for individual forests and minor land subdivisions.
(3) To prepare vegetation maps for all classes of forested land, based on the broad vegetation and volume-per-acre classes.
(4) To survey the extent and degree of natural reproduction of forest and the extent and nature of deer and other animal damage, to superimpose land ownership boundaries on the vegetation maps, and to survey all types of non-commercial and protection forests.
The methods used depend largely on vertical air photographs (scale of 1:16,000) from which accurate acreages can be obtained without detailed ground surveying. The ground-sampling phase of the survey has been designed on a statistical basis and definite standards of accuracy have been set. The final results, which will not be available for several years, will be of known and acceptable accuracy and will form the basis of the Dominion's timber-use economy for at least the next 50 years.
At the Rotorua Forest Experiment Station, a national herbarium for both indigenous and exotic forest species is being built up, largely from material collected by officers engaged on the National Forest Survey. An exotic forest arboretum established in 1900 in the vicinity of the Experiment Station is being maintained and expanded to include both exotic and indigenous species.
Characteristic research problems engaging the present attention of the New Zealand Forest Service in general and the Forest Experiment Station in particular are reviewed briefly under Sections III, IV, and V.
The various administrations responsible for New Zealand's forests have had opportunities to learn much from past errors and omissions. Perhaps the greatest lesson, only recently learned, is that little real progress can be made until there is sufficient trained staff to manage commercial forests intensively and at the same time carry out without interruption a research program primarily designed to improve and extend such management.
Much has been done since the last war towards achieving this combined objective. Prior to the war, higher forestry education was provided by the University of New Zealand at two Colleges for a brief period but was discontinued during the depression, partly because of failure to recognize the national importance of maintaining one institution providing adequate facilities for both education and research instead of two inadequately equipped schools.
Lack of general recruitment during the prewar decade following the depression, and the absence of young graduate foresters in particular, created serious gaps in the cadre of Dominion foresters in both executive and research capacities. To meet this staff emergency, the Forest Service adopted, towards the end of the war, a long-term plan for the regular recruitment and training of apprentices and all other grades of forest officers. One outcome of this policy decision was the annual recruitment of some 20 carefully selected youths; a small proportion of whom were provided with facilities to study for a basic science degree (B.Sc.) as a prerequisite to higher forestry education, the reinstitution of which the Forest Service is vigorously advocating. The recruitment and training policy was not, however, confined to staff apprentices, and in 1944 a departmental Training Centre was established at Rotorua (in the same location as the future Forest Experiment Station) and within the organization of the Development Division.
Since its establishment, the Training Centre has provided a continuous series of short courses for workmen, and for clerical and field officers. These courses are designed for recruitment, refresher, and promotion-qualifying purposes. The results achieved have gone a long way towards meeting the acute current staff shortage. They have also established a successful precedent for a more ambitious forestry educational plan to provide professional and subprofessional training in intimate association with the Forest Experiment Station.
In 1938 and 1948 the key field staff of the State Forest Service (excluding clerical and specialist officers) was:
|
|
1988 |
1948 |
|
Graduate Foresters |
6 |
34 |
|
General Division Officers (all grades above and including Forest Rangers) |
70 |
126 |
|
TOTAL |
76 |
160 |
The number of foresters is still inadequate, but the increase since 1938 has made possible a move towards more intensive management of national forests and a greater emphasis on research. An exceptionally vigorous policy of both internal and overseas recruitment has achieved these results and only now, in the continuation of this policy, is the forestry authority of this Dominion able to look forward with some degree of optimism to the gradual solution of the many outstanding problems in both indigenous and exotic forests.
* Contributed by John T. Holloway, Forest Experimental Station.
Enquiry into the fundamental nature of the indigenous forests of New Zealand and their capacity for permanent yield management has largely been sterile of significant results. In the first place, the most urgent requirement was not to maintain the forest but to replace it by productive grasslands and to maintain these grasslands. Secondly, much of the work that was carried out was vitiated by too rigid adherence to the concepts of overseas ecologists and silviculturists without critical enquiry into the local applicability of such ideas. The wholesale adoption of European and American terminology and theory delayed technical advance, a delay aggravated by faulty liaison and lack of mutual understanding between botanist and forester. Botanists have tended to supply blanket theories to "explain" all podocarp forests, or all Nothofagus forests, while the foresters, because such theories obviously were inapplicable to particular forests, rejected the explanations, regarded the botanists as impractical theorists, and resigned themselves to a simple empirical approach. This approach has yielded much information of value, particularly as concerns the Nothofagus forests. Progress has been slow, however, mainly on account of perennial labor shortages and lack of trained staff - handicaps rendered more serious by the almost complete absence of any market for minor forest produce, and by popular relegation of permanent forests to areas remote from centers of population.
The extent to which the foresters' findings and the botanists' theories can be applied is not yet known. Progress now hinges upon re-examination and supplementation, assisted by air survey, of the descriptive data, upon reinterpretation of the facts, the correlation of theory and practice, and the initiation of wider scale field experiment directed in accordance with up-to-date, local findings.
Recent work suggests that the indigenous forests of New Zealand have been in an essentially unstable condition since the date of European settlement a century ago. Their distribution does not reflect present climatic conditions but the climate of a warmer and more humid period. In particular, the bulk of the softwood podocarp forests display symptoms of overmaturity and stagnation with a virtual absence of young growth. The economy of the timber-producing industry demands that utilization of such relict forests be intensive to the point of full exploitation. The consequent destruction of microclimates prohibits the re-establishment of the original type of forest under the present regime. The second crop consists mainly of worthless and malformed hardwoods. The podocarp forests seem vigorous only on special lowland soils, and it is only on these soils that adequate regeneration can be secured; but these same soils can be converted to high quality dairying pastures and they must be utilized for food production. The podocarp species is also intractable to normal forest nursery and reforestation practice. No reliance can be placed upon the podocarps for permanent yield of softwoods. They are restricted to sites where local conditions are particularly favorable and where the land is not required by the farmer. Podocarp forest research must be designed to delimit such areas; more urgently, it must aim to divert the forests following logging away from the scrub hardwoods toward more valuable species. In many cases these species may have to be exotics.
The hardwood Nothofagus forests present a less difficult problem. At least five species of Nothofagus are involved, but the accurate determination of these and of their many hybrids has not been achieved by the taxonomists. All of the species, however, have more favorable silvicultural characteristics than any of the podocarps. For these forests also, the major problem is to determine where the various species exist by virtue of present climates and where they are survivors from the past; it is only in the former that management problems are likely to be solved satisfactorily. Each species varies widely in its site requirements for different phases of its life cycle. For example, conditions favorable to regeneration of a species are not necessarily the same as those which promote rapid growth or optimum size at maturity. Within the virgin Nothofagus forests rapid readjustments of species to site are in progress while Nothofagus species, wherever such forests are contiguous with or contained within podocarp forests, tend to extend their area at the expense of the podocarps. Permanent management of the Nothofagus forests depends upon recognition of the areas in which the desired species are aggressive and selection of sites within those areas where regeneration, growth rates, and form are good. Under present conditions the species which is now considered of least value is aggressive over wide areas. Successful management will depend here upon the development of a suitable market. For each species, within its optimum range, silviculture is likely to be similar to that employed for Fagus sylvatica in Europe.
The third major problem facing the indigenous forest research worker in New Zealand is that posed by deer, wapiti, opossums, pigs, goats, and cattle graze in the forests unchecked by the presence of any predators. If the forests are regarded simply from the point of view of timber production, the result appears beneficial since the preferred food plants are mainly silvicultural weeds. Unfortunately once these weeds are eliminated the major species are browsed on or otherwise damaged. In areas where the existing forest is unstable, changes are accelerated. Elsewhere the final result cannot be forecast since the virgin forest canopy is still intact. This problem is particularly serious: the greater part of the forests affected are watershed protection forests of mountainous terrain with high rainfall, the country as a whole is dependent for power on its hydroelectric resources, and agricultural production is concentrated on the flood plains of the rivers.
ORGANIZATION CHART NEW ZEALAND STATE FOREST SERVICE
It will take some time to arrive at the solutions of these various problems; but the work should proceed more quickly now that well-defined research projects are under way, and the limited technical staff can be used to better advantage.
*Contributed by A. Priestley Thomson, Officer-in-Charge Forest Experiment Station.
New Zealand's exotic forests cover some 344,000 hectares (850,000 acres), more than half of which is State Forest. The most important species is Insignis pine, Pinus radiata, which occupies 63 percent of the total area; others represented in large quantities are Corsican pine, Pinus nigra, lodgepole pine, Pinus contorta, western yellow pine, Pinus ponderosa, and Douglas fir, Pseudotsuga taxifolia. Less important species which have been successful on certain sites are European larch, Larix decidua, redwood, Sequoia sempervirens, western red-cedar, Thuja plicata, Lawson's cypress, Chamaecyparis lawsoniana, Monterey cypress, Cypresses macrocarpa, white pine, Pinus strobus, and the southern pines Pinus palustris, Pinus caribaea, Pinus taeda, and Pinus echinata.
The major problem in exotic forestry is a management one which arises from the extreme maldistribution of age-classes and the preponderance of the one species Pinus radiata. The problem would be more easily surmountable if the forests were normal in other respects. Unfortunately they are not.
These forests were planted in the last 50 years, most of them during the plantation boom of 1923-1936. The earlier plantings were generally done carefully, with due attention paid to correct nursery and establishment techniques, to careful siting of species and to the use of suitably close planting distances. Very little thinning, however, was done. On the other hand, during the boom period almost every silvicultural mistake was made. Not invariably, but too frequently, cheap seed was used, poor tree-stock was sent out from the nurseries, the planting technique was crude, and little attention was paid to maintenance. Furthermore the sites chosen were often very poor, an insufficient attempt was made to meet the site requirements of individual species, and the planting density was invariably 1,600 trees per hectare (640 trees per acre). Again no thinning was done. In this period of extensive forestry the emphasis was on quantity rather than quality and the costs in all operations were kept to a minimum As a result, there is now a large area of low quality and understocked stands, badly distributed as to age-classes and species representation and exhibiting the greatest variability in tree type, tree form, and amenability to silvicultural treatment.
The immediate research program, therefore, must be directed towards efforts to improve unsatisfactory conditions during the first rotation. In the poorly stocked stands of fast-growing species there is little that can be done, except perhaps a high pruning and light thinning of those compartments which for one reason or another must be left to overmaturity. In the better stocked stands, and for the slower growing species the problem is how to catch up with arrears in thinning. The response to different grades of thinning at different ages and on different sites is in need of thorough investigation, as are the economies of thinning and the most practical means of carrying out the work. Since forest labor is expensive and in short supply the problem is as much one of administration as of research. The important questions are tactical in nature, e.g., for what species and on what sites will the limited labor force be put to best advantage? Already much is known. It has been demonstrated for instance that even 4' x 4' Pinus radiata will produce a high sawing yield with no thinning at all; and conversely that Corsican pine at a similar spacing will stagnate and not produce any trees of saw-log dimensions. To what extent thinning of other species and of Corsican pine at wider planting distances is essential rather than desirable is the question which the research branch must answer; and the answer must be accompanied by specific recommendations as to thinning grade and thinning eyelet The problem is rendered more difficult by the paucity of reliable sample plots.
The major research future in exotic forestry, however, is concerned more with the next and subsequent rotations of existing forests. Further, since New Zealand still has more than 400,000 hectares (1 million acres) of nonagricultural land that is climatically and edaphically suited to the growing of softwoods, the existing area may be considerably extended. The problems involved will call for a vigorous research program.
Investigations must be made of silvicultural characteristics, tree types, tending regimes, forest pathology, soils and soil relationships.
Silvicultural Characteristics. With the important exception of Pinus radiata, the main species used in New Zealand are well known in the countries of origin. Their silvical characteristics have been described and suitable silvicultural systems evolved. The results of overseas experience, however, are less useful than might be expected since most species behave differently and quite often quite unpredictably in this country. Much has been learned in New Zealand over the last 50 years but the information is fragmentary in nature and little has been collated or put on record. One of the major basic research projects, therefore, must be a detailed qualitative examination of all species as they grow in New Zealand. This work which is already under way will not only describe the individual tree characteristics, both morphological and phenological, and the normal course of stand development on different sites, hut will also attempt to evaluate the optimum and limiting site factors, the effects of mixtures, and the conditions necessary for successful natural regeneration.
Tree Types. At least four of the major species used in New Zealand show marked variation in tree type. In Corsican, lodgepole, and western yellow pine the natural range of the species is wide and the types found in New Zealand are true geographical races. Pinus radiata on the other hand has a limited natural distribution and its variability must arise from other causes. In all species, site has a profound influence and often masks the inherent genetical characteristics. The first problem, therefore, is to determine the extent to which observed differences are genetic rather than environmental in character, and a series of progeny tests are envisaged. Concurrently, studies are being made to decide on the most desirable type for a given site and a given purpose. In most cases, type improvement must result from eugenic thinning practices, but attempts will be made to accelerate the process. Thus elite stands are being formed, research on the technique of vegetative propagation has been commenced, and plans are being laid for a program of work on controlled fertilization. New Zealand, incidentally, by reason of the fast rate of growth and early maturing of many species, offers a unique field for the tree breeder. As examples, lodgepole pine has been known to bear fertile cones at 5 years from seed, Pinus radiata at 6 years, Pinus pinaster, Pinus muricata and Douglas fir at under 10 years, and Pinus patula, Pinus taeda, Pinus caribaea, Pinus nigra, and Pinus ponderosa all at under 15 years.
Tending Regimes. As New Zealand's indigenous timber resources dwindle, increasing reliance will be placed on exotic species for all wood products. Hitherto, the public has not considered the exotic forests as a source of high quality timber. They have been invaluable, however, for supplying the local box and pulpwood industries and they have provided, from short rotation stands, a large quantity of low to medium grade sawn timber which is finding increasing use in the building trade. In the future they must replace the staple indigenous timbers, rimu, Dacrydium cupressinum, matai, Podocarpus spicatus, and totara, Podocarpus totara, as the primary source of building material. It is hoped that they will also supply a much expanded pulping industry. The two major objectives of management will be: (a) the provision of clean high-quality heart timber on a long rotation, and (b) the provision of heart-free pulpwood on a short rotation.
The research program will be directed towards the most efficient means of achieving these ends. Apart from further species and spacing trials it will involve a comprehensive of permanent sample plot work designed to study the effects of different primary regimes, different thinning intensities, and different thinning cycles. As with all plantation work, the objectives will be to determine, for each species, for each site, and for each object of management, what original spacing distance, and what subsequent tending regime will be the most economical in producing the optimum yield.
Populus robusta, planted in 1937, at Whakarewarewa, North Island.
Forest Pathology. By great good fortune, New Zealand's large areas of pure even-aged plantations are singularly free from any serious insect or fungal attack. Only in the worst instances of faulty siting have outbreaks of epidemic proportions occurred. Nevertheless the risk is always there. Research in forest pathology at the present stage is basic in nature and consists of studying the ecology and life cycles of the most important insects and fungi. Concurrently preventive measures are being studied.
Soils and Soil Relationships. Very little work has been done on the soils used for exotic forestry; in particular, their ability to meet specific nutritional requirements has received little study. Most forests show no signs of any mineral deficiency but an important exception is a group in North Auckland occurring on badly podsolized clays, known as "gumlands." Here soil is the limiting factor in healthy tree growth, and research in tree-soil relationships and in ameliorative measures will be necessary.
The pumice soils of the central volcanic plateau of the North Island are the most important soil group supporting exotic forests. They pose a soil problem which may become significant. Various pumice showers are represented, the most recent of which are basic in nature. These maintain their structure under forest cover and show every sign of continued fertility. On the more widespread acidic showers, however, a process akin to podsolization is rapidly developing. As in normal podsolization the tendency is for a black crumbly A horizon to be completely replaced by a structureless ash-grey layer. The mechanism is apparently far more complex than simple leaching and is thought to be due to soil fungi acting on the incorporated humus. What effects this process will have on future increment and what ameliorative measures (if any) will be necessary are the major problems on forest soils in New Zealand.
* Contributed by J. Stanley Reid, Engineer in Forest Products.
The approach to these problems in New Zealand, as in other timber-producing countries, has been along the lines of (a) fundamental research, and (b) applied research.
Fundamental research is concerned with the mechanical, physical, and chemical properties of timbers produced locally and, to a more limited extent with timbers from adjacent islands. These timbers have been examined critically with regard to physical properties, i.e., density, shrinkage, peculiarities affecting seasoning, microscopical characteristics and identification, durability, working properties, and other general features which affect their use. The mechanical properties have been studied and comprehensive tests made of the more important basic strength properties of practically all the commercial timbers; the chemical nature of substances in a number of the woods has been the subject of the third important group of investigations.
Applied research in forest products has embraced those numerous problems concerned with technique in efficient preparation, marketing, and use of timber and other forest products. Typical of processes included under this heading are grading, seasoning, and preservation of timber. A reasonable approach to these matters must have regard for the feet that a great deal of work done overseas provides a useful guide to what is practicable and economic. Hence it has been possible to adopt some of those practices without substantial alterations. Studies of properties, included under fundamental research, enable comparisons to be made between local timbers and overseas timbers. In those eases in which resemblances are close, it is possible to indicate directly the potential uses for the timbers, the grades required for those uses, and the consequent method of sawing to produce the grades. It may even be possible to indicate kiln schedules which are suitable. As regards wood preservatives, there are many treating methods and preservatives which have been proved satisfactory; applied research will then involve comparison of service conditions as these are the determining factors in choice of treatment methods and specifies.
Attention has also been given to the wide range of forest products other than sawn timber and natural round or hewn or split products. Processes for conversion of wood waste apply to local timbers as to overseas timbers but economies have always to be considered very fully; this comment applies for instance to pulping processes, to wood alcohol manufacture, destructive distillation, fuel briquetting, and wood flour manufacture.
Forest products research in the future will give more emphasis to the planted forest species and to the native forest species which will continue to provide substantial quantities of timber.
A problem is created by the threatened exhaustion of indigenous softwoods in the not far distant future - certainly wood-using practices will radically change, even if these forests continue indefinitely to contribute a useful quantity. A few years ago over 80 percent of the local production of sawn timber was from the native softwoods, which are notable for their yield of exceptionally clean timber with a substantial proportion of heartwood of high natural durability, and for their remarkably close and even texture and consequent even-wearing. These timbers are also strong and show relatively little variation in density and strength; they are not highly decorative but yield good clear veneers; and, in addition to having the advantage of durability, the heartwood responds slowly to change in atmospheric moisture.
Today, the indigenous softwoods still comprise about 60 percent of the output, but the exotic softwoods are coming rapidly to the fore as the major general-purpose timbers of the future. They are lighter in weight than the native softwoods, contain numerous defects, are variable in density and strength, are very subject to decay and to shrinkage and swelling, offer some difficulties in painting, and do not compare favorably in certain respects with timbers they are, broadly speaking, destined to replace.
Nevertheless, they can be adapted very well to those purposes an-d therein lies an important aspect of timber research in New Zealand.
The ability of native hardwoods to regenerate naturally (such as Nothofagus species in particular) has stimulated research on their potential uses. For instance Nothofagus cliffortioides has been studied first of all from the anatomical angle to determine the relationship of its timber to the timbers of its sister species, its variability and the character of cellular inclusions. It was a natural step to link the silica concentrations shown by the microscope and chemical tests to sawing problems; the studies of variation of density and shrinkage, of strength properties, seasoning, grading, and uses follow naturally. Another hardwood, tawa, Beilschmiedia tawa, had been little used as a timber because of its many shortcomings in comparison with most other New Zealand timbers; improved seasoning, grading, and preservative treatment now place it in the high-quality white hardwood group.
In brief it will be apparent that forest products research will be increasingly related to forest management in the wide sense. This is exemplified by the specific gravity, shrinkage, and related studies which have been made to determine the effect of age, height, espacement, climate, and soil on the physical, mechanical, and chemical properties of timber from planted forest species (e.g. Pinus radiata). As a necessary corollary to such fundamental research will be the numerous applied research studies concerning timber grades, air-seasoning and kiln-drying technique, correct preservation practice, and extended utilization.
As private companies and local bodies control some 200,000 hectares (500,000 acres) of exotic coniferous forests in New Zealand, there is, as might be expected, considerable interchange of technical information mainly through Forest Experiment Station channels. Volume tables prepared by the Station have been made available to companies and the data obtained from private stands have been used to advantage by the Experiment Station.
There is considerable research liaison between the Forest Experiment Station and the Department of Scientific and Industrial Research whose Geological Survey, Soil Bureau, Plant Diseases, and Botany Divisions have provided valuable co-operation and have, in turn, benefited from observations and collections by National Forest Survey field staff, in particular. The Biometrics Section, also of the Department of Scientific and Industrial Research, acts in an advisory capacity in the application of statistical methods to current forest research.
In the field of forest products, there is liaison with the Dominion Laboratory (Department of Scientific and Industrial Research) in derived products, principally fundamental chemical research on wood.
High pruning of Douglas Fir, Pseudotsuga taxifolia, at Rotorua, North Island.
In furtherance of the standardization of national wood-using practices, including preservation, the Forest Service is represented on various committees convened by the Standards Institute which is a departmental organization functioning under authority of the Standards Act, 1941.
Close collaboration is maintained between the Soil Conservation and Rivers Control Council (a statutory body established by Act of Parliament in 1941) and the State Forestry Service through a full-time Forestry Liaison Officer. One of his functions is to represent forestry interests in soil conservation research.
The University of New Zealand (owing to heavy postwar teaching commitments and to limited staff) is at present doing little basic research in the biological sciences and consequently forestry research liaison is negligible. Considerable numbers of advanced students, however, seek forestry experience during vacations, and this is provided by the Forest Experiment Station (in particular by the National Forest Survey) to mutual benefit.
Photographs for this article were provided by courtesy of New Zealand State Forest Service.
