by
Colin Bassett
Director of Research
NZ Forest Service,
Wellington, New Zealand
INTRODUCTION
At the time of the main European settlement of New Zealand in the mid 19th century it has been estimated that forests covered some 14 million hectares or 56% of the land area. Within a relatively short time millions of hectares were cleared and burned to make way for pasture. The native forests also supplied the country's timber needs and timber for export. From early in the 20th century plantations were established mainly of Monterey pine (Pinus radiata D. Don), and wood from these has steadily substituted for that of the native forests, now making up about 90% of the country's annual production of approximately 9.5 million m3.
Clearing for farming and sawmilling has reduced the native forest area to approximately 6.2 million hectares or 23% of the land area. Disappearance of the forest has been greatest from lowland areas.
THE NATIVE FORESTS
The long isolation of New Zealand has led to a flora with a high degree of endemism. The forests may be placed in four broad classes:
Kauri - podocarp - hardwood
The kauri (Agathis australis Salisb.) is a magnificent large tree found north of latitude 38° in various associations with rimu (Dacrydium cupressinum Lamb.), miro (Podocarpus ferrugineus G. Benn. ex D. Don), totara (Podocarpus totara G. Benn ex D. Don), tanekaha (Phyllocladus trichomanoides D. Don) and many other species.
Podocarp - hardwood
This class covers a great diversity of forest types ranging from dense podocarps with associated hardwoods being a minor element, to scattered podocarps with a strong hardwood element. A number of hardwood species, such as tawa (Beilschmiedia tawa (A. Cunn.) Benth. et Hook. f. ex Kirk), pukatea (Laurelia novae-zelandiae A. Cunn.), kohekohe (Dysoxylum spectabile (Forst. f. Hook.) and puriri (Vitex lucens Kirk) are confined to a more northern distribution.
Podocarp - hardwood - beech
This class also embraces a diversity of forest types with various associations of podocarps, the four species and one sub-species of Nothofagus Blume and other less prominent hardwoods.
Beech
Once again there are complex patterns of forest types ranging from pure stands of a single species to various mixtures of the species.
This classification is a gross over-simplification: the forest types and sequences of types are of considerable complexity.
POLICY ON RESERVATION OF FOREST
More than 1½ million hectares of indigenous forest is reserved in New Zealand's ten national parks and non-State-forest reserves. However, the national parks are mainly in mountainous areas and do not include all types of forest. If a comprehensive range of representative forest associations is to be retained, it is therefore necessary for reserves to be established in the indigenous State forests, which are outside the national park system.
The New Zealand Forest Service has “a basic philosophy of ecosystem conservation (that) will result in a New Zealand network of scientific reserves in State forests” (Thomson and Nicholls, 1973). The Government-approved management policy for indigenous State forests incorporates this philosophy (Anon. 1977).
The Forest Service has therefore established a multi-disciplinary working group to recommend areas for reservation. The nine-member group is made up of scientists from the Forest Service, the Department of Scientific and Industrial Research (DSIR), the Ministry of Agriculture and Fisheries, the Ministry of Works and Development, the Wildlife Service of the Department of Internal Affairs, and the Royal Society of New Zealand. The members are specialists in forestry, botany, soils, hydrology, native freshwater fishes and bird life. Other specialists are frequently called on to assist the group.
The working group was established in 1974 initially to advise on the scientific aspects of proposals for the utilization and management of South Island beech forests, including reservation for scientific reasons. Its responsibilities were later extended to advising on reserve proposals for all indigenous State forests.
OBJECTIVES OF RESERVATION
The reasons for the reservation of indigenous forest for scientific purposes include the following:
To retain examples of the indigenous flora and fauna.
Having evolved in isolation for some 80 million years a large proportion of the New Zealand flora and fauna is unique. New Zealand therefore has a special obligation to follow accepted international practice and to retain representative examples in their natural state.
For the study of natural ecological processes.
Undisturbed forest preserves the diversity of plant and animal species and their geographic races, expresses various stages of ecological development and permits the measurement of continuing ecological processes. There is an obligation to national and international science to retain representative areas for these purposes.
As baselines for measuring change.
It is important that in the long term the changes that follow from man's occupation and use of the land can be measured and understood, so that undesirable trends can be recognised and corrected. To achieve this, areas broadly typical of a region need to remain undeveloped so that comparison can be made between these reference areas and disturbed areas that were once comparable.
To maintain genetic diversity.
It is scientifically desirable to maintain the genetic diversity of individual species. In the absence of knowledge of the extent of this diversity, this ideal may possibly be approached by ensuring the continued existence of species broadly over their natural range.
SELECTION OF AREAS FOR RESERVATION
Ecological districts
New Zealand is a mountainous country, strongly dissected in many places, with a diverse geological history and quite marked climatic contrasts. This diversity permits the delineation of “ecological districts” which are rather subjectively defined areas based principally on unifying features of vegetation pattern, local climate, geomorphology and soils.
The individual areas are described rather than defined precisely by these parameters, but the concept is nevertheless useful for identifying ecological units of broad uniformity.
Representative areas
Once ecological districts have been defined the exercise becomes one of selecting a representative area within each district. The patterns and sequences of forest types usually reflect variations in other characteristics, so selection of an area containing a representative range of forest types may go a considerable way towards securing areas adequate to represent a wide range of other scientific values. Because changes in forest composition often follow altitudinal gradients, many of the areas selected for reservation extend from lowland forest to the mountain tops. Other environmental gradients can also be important.
Special areas
There are sometimes distinctive features which could not be accommodated within the representative areas in which case additional smaller reserves are proposed.
GUIDELINES FOR DEFINING RESERVES
To assist in defining areas for reservation the working group has developed guidelines on the shape, size and other features of the ideal reserve. These are:
It should represent the full range (both virgin and already modified) of land forms, vegetation and soil sequences, and animal communities of the region. (The group has subsequently agreed, however, that it is not practicable to reserve the full range of modified features. The reserves it has recommended do include modified areas but by no means the full range).
It should be large, with say a minimum of 1 000 ha; a single large reserve is preferable to two or more smaller reserves of the same total area. This is particularly true for preserving the greatest diversity of bird populations. It is considered legitimate to create small reserves to preserve unique features or special values, although these could present special problems in protection.
It should include at least one complete undisturbed catchment of a permanent waterway.
It should have a compact shape, with the minimum perimeter for the area involved.
Wherever possible, its boundaries should be clearly defined by natural features.
It should be unroaded, at least within the main catchment.
The group has recommended that the reserves be known as “Ecological Areas”.
THE RESERVE PROPOSALS
The reserve proposals are generally put forward by the Conservator of Forests responsible for administering the State forests of the region being considered, and are usually based on the advice of the forest ecologists of the Forest Research Institute. Suggestions may also come from other organisations such as the Botany Division of DSIR.
The working group examines the proposals in the context of the region's forest ecology and other scientific knowledge, and inspects the areas on the ground wherever possible. It considers such matters as whether the areas meet the guidelines sufficiently, whether all known scientific values are provided for, whether the areas should be modified to include specific additional values and whether they duplicate reserves already in existence.
The group may recommend that an area be accepted as originally proposed, that it be enlarged or reduced, that another area be substituted for it altogether, or that it not be accepted. In practice the most frequent recommendations are to accept the area as proposed or to extend it to enhance its scientific value.
MANAGEMENT AND USE OF ECOLOGICAL AREAS
The New Zealand Forest Service considers that reserves dedicated as Ecological Areas need to be managed and that, to realise their full potential, research should be encouraged in them. Public access will often be compatible with retaining the scientific values and should be permitted where this is so. To facilitate multiple use that is compatible with the preservation of scientific values the committee has prepared recommended guidelines for the use and management of Ecological Areas.
It is intended to publish maps and descriptions that identify the scientific values of each area accepted for reservation, so that scientists will know what is available for study.
In accordance with the indigenous forest policy it is also intended that a multidisciplinary scientific panel will advise on and co-ordinate scientific studies undertaken in Ecological Areas.
PROGRESS TO DATE
The working group meets three times a year, for a week at a time, in regions for which reserve proposals have been formulated and are ready for consideration. The proposals are usually explained to the group by the ecologists who formulated them.
Reserve proposals have been considered in six different forest regions of varying size, and 55 areas totalling more than 152 000 hectares have been recommended for reservation as Ecological Areas. They range in size from 120 ha for the smallest special purpose area to 15 500 ha for the largest representative area.
In the largest region examined, the northern West Coast of the South Island analysis of the recommendation for part of the region shows that for the seven broad forest categories present, the areas recommended ranged from 8% to 20% of the land area of that forest category at the time of the National Forest Survey in 1955. Analysis on this basis is considered to give a fairer picture of the proportion reserved than would a calculation which used the much-reduced present-day land areas remaining in forest as a basis.
It is estimated that within 3–4 more years the task of identifying a national network of Ecological Areas in indigenous State forests should be virtually completed.
REFERENCES
Anon. 1977 Management policy for New Zealand's indigenous State forests. NZ Government Printer, 15 pp.
Thomson, A.P. and Nicholls, J.L. 1973 Scientific reserves in New Zealand indigenous forests. NZ Journal of Forestry 18 (1): 17–22.
