NATIVE TIMBER FORESTS

Chronicle (Levin), 28 December 1946, Page 6

NATIVE TIMBER FORESTS

Conserve, Renew or Replace Wliilo everybody wislies to preserve native fo reata, not overybody understarnls tlie practical question of whethcr a liative timber-ploducing foreat (as apart from ' ' jirotection " or water-' regulating forests) can be kept in continuous production by renewing the forest after the removal of mature trees. Can kauri, or beech (alias "birch";, or rimu be regenerated and brought to maturity in suiiicient nuinbers and in a sufficieutly ahort time to make a native forest commereially possibJe as a permanent timber-produeing forest? To .this practical question the New Zealand Institute of Foresters, through its.President (Mr. Owen Jones) and its Piiblie Kelations Ofiicer (Mr. A. L\ Thomson), supplies the following answer, backed by the institute 's techuical authority. j The New Zealand Institute of Foresters is an independent organisation whose stated objective is to furtlier the | development of technical forestry in ' New Zealand. It realises only too well that this objective cannot be gained and New Zealand cannot have an intelligeut forest policy, unless a wellinformed forest consciousness cxists throughout all sections of the coinmunity. Most Natives Too Slow, But — • The institute is mainly coiitlemed with the jilea for the re-establishment of native forests and criticism of the present policy which gives such prominence to the use of exotic species. We believe that this policy is inevitable, and having regard to known and proven 1'acts, that it is the only correct one. in sunimarised form, these facts are: Firstly, that most of the valuable native species are far too slow-growing to •give any i>rospects of a second timber crop within a measurable period of time; secondly, that fliey do not lend themselves readily to re-establshment techniques, wliether by planting or by aaturai regeneration; and thirdly, that a large variety of exotic species have pi-oved themselves in New Zealand to iie fast-growing, easy to handle in both inirscry and young forest stages, and eminently suited to New Zealand 's climate and soils. This does not mean that the institute is uncoucerned about the perpetuatiou of indigenous forests. On the contrarv, j it believes that every effort shoubl be I made in this direction, and, in particu):ir, that energetie steps shouhl be takou to rehabilitate the devastated cut-over areas, to place the remaining virgin forests under sustained yield management, to foster and encourage the development of such young native forests as exists, and assiduously to proteet the important liill country protection forests from destruction by fire or by grazing. An enlightened forest administration is duty liound to do all these things; it is encouraging to note I in recent reports of the State Forest J .Service that the Director of Forestry l places 110 less importance upon these | phases of the Dejiartment's activities than he does upon the provisiou of immcdintc timber supplies by the estab- { lishruent of fast-growing exotics. In disrussing tlie question of the present and future management of indigenous forests, it is important to rcalise that tiirej distinct types of problems I are iuvolved, corresponding broadlv to j the tliree major forest types found in i , New Zealand. These are.. kauri forests, beech forests, ah^-.fjic .fey^est groupy-. ; inclticiing rima, * Tbfera, .^-iuatai; railS^j kahikatea, the podbctirp fp'fests. -■ ; h Kauri is Not so Slow. Regarding kauri, the positioh'is very ] liopeful. A iuucli reduced but quite ' •onsiderable area of kauri still exists,

most of which is owned and administered by the State. To the best of the institute 's knowledge, the State Forest Service is managing these forests according to the principles of sound and generaily accopted forest practice. Ctiven the right conditions, kauri as a siiecies will regeherate well. As a species also, and when compared with most other native trees, it is relatively fast gi'pwing. It is possible, therefore, s'o "tO' regulate the cutting of kauri that tlie voiume of timber removed over a period' is equal in arnount to that put on by new growth over tlie same period. Necessarily the dead and over-mature trees niust be harvested iirst, sb that the maximum growth will be put on by younger and more vigorous trees so that the right conditions will be induced for the germination of kauri seed and the development of the young trees. The exact prescriptions necessary to control this procedure have been embodied in the forin of a working plan. Axiproveu and signed by the appropriate autliorities, this working jilan is now |iart of tlie law of the country, and by it, the productive life of the remaining kauri forests is guarauteed iu perpetuitv. For the beech forests, the position is also liopeful. Although not yet playing a major part in tlie country 's timber economy, two sx>ecies at least are of great potential value. They are red beech and silver beech. Both regcnerate very freely under certain conditions and forosters have no doubt that these conditions can be satisfactorily induced. Technically there are no msuperable ditliculties in putting .tlie beech forests under the samo type of sustaiiied yield management as is praetised with ka.uri, and such xireseut difliculties as do exist are more coucerued ivith the legal and economic aspeets of the problem. Ilowever, large areas of beech forest are still untouched, and since the saw-miilirig iiidustry is not encroaching into tliem as rapidly as it is into the podoearp forests it is more tlian likcly that scientilleally managed beech will play an iucreasingly important part in tlie future of New Zealaud forestry. As with all types of forests, of course, the successful perpetuatiou of beech is wholly dcpcndcut upon adequate protection from introdnced grazing animals and, above all, from fire.

Kimu Centuries Old. Turning to the podoearp forests, the prospects are not nearly so encouraging. Rimu is the main sjiecies and, as is well known, is the tree upon which New Zealand largely relies for her timber requirements. Rimu has a very slow growth rate, and tlie trees at present being milled vary in age from 250 to 600 years or more. Foresters believe that even under management, a period of at least 200 vears would be neces^iry before a second crop could be obtained. Unfortunately, rimu is an infrequent and sparse seeder, and, except in parts of the West Coast, it does not regcncrate freely. Moreover, except in the case of garden specimens given liorticultural treatment, it has been found impossible to handle in its seedling stages, whcther these have been raised artihcially in nurseries or have been naturally regenerated. Whereas it would not be correct to say that tliere is no way of managing a rimu forest so that a second, crap is guaranteed, thB' fact remaiiAthcit -foi-esters have not yet found theiway,: in.'spite!of inany years of patiep# tryifig. •, Prestnt indications are that if rimu can be re-establislied at all on a. large scale, it can only be done tlir'ough tho medium of an inter- - -flttfSi}:; .ci«p.^-%luch alone would cbiiditions liecessary for the dfev'eldpiiiextt oi tlie young trees. It is ndt possible. to raise rimu in artilicial plantations as can b 0 donc, for instance with pine and Other exotic species. Wliat is true for rimu is true also

with miuor modi/icatious for totara, matai, kahikatea. No satisfactory techuiquo has.beeu evolved to rogeuerate tliem nat'urally aud attempts to estab lisli tliem artihcially have failed. Even if this were not so and second crops > wero already under way, a wait of sevcral hundred years would be necessary before tho trees would be large enough to harvest. This being the case, and tlie remaining native forests being far from inexhaustible, it becomes ob vious that New Zealand must look to some other source for its future timber requirements. The Forest Service has realised this for many years and accordingly has established large areas of fast-growing introduced species. Justilication for this iiolicy is already apparent in that- no less than one-third of tlie timljer used in New Zealand in 1915 caino from such exotic iilantations. Without tlie forethought shown by a past generation of foresters the present timber sliortage would be far more acute than it is. New Invasion of Native Trees. » In general terms therefore New Zealand 's forest administration mu>t evolve along two parallei liiies. Oue is to guarantee an adequate timber sup-

plv for the country bv the establishment of fast-growing exotics; the other is to conserve the remaining native forests and develop them to the maximum of their productive capacitv. Perliaps ; the most disquieting feature in tho present pieture is that the milling iiidustry is now moving into the few remaining. large areas of valuable native forest. By the time the problems of rimu silviculture and management liave been solved it' seems that there will be little virgin forest left to manage. The only way out of this dilemma would be to lock up all such areas for a period ol: years, meanwhile earrying out intensive research and experimentatiou into different management techniques. Huch a step would necessitate a drastic curtailnient in timber production. With the present timber and housing sliortage, it is most unlikcly that the general public would bc prcpared to countenance this policy, no matter how desir- . able it mav be from the long-term rftV f ifd1 Th e' IgWrl fei-aP "jViit)) ic ' after all, are the ultimato ownors of the forests.