GROWTH OF RIMU BUSH

Hokitika Guardian, 11 September 1931, Page 2

GROWTH OF RIMU BUSH

PERMANENT TIMBER AREAS. RAPID REGENERATION. IMPORTANT EXPERIMENTS BY SCHOOL OF FORESTRY. (Christ church “P re ss. ”) If the result's of experiments in the growth and regeneration of the rimu tree, now being conducted by the Canterbury School of Forestry, are confirmed by finjal readings at the end cl 1832, it is confidently expected that the rimu bush in Westland may be made a permanent timber-producing area of great value to the Coast and to the Dominion. By scientific observation is has already been found that the processes of growth and regeneration of this tree fare more rapid than.has ever been supposed. Under a proper system of forest management there seems,, therefore, little doubt of the permanency of tlie bush areas and the:r profitable use. More than ten years ago the State Forest Servire established an experimental forestry station at Rimu, about seven miles from Hokitika. This ( srtn» tion comprised fan area of about 7000 acres, containing not only much cutover bush country, which had been repeatedly burned and grazed but also small areas of virgin bush of different ages and types. DO U B LE INV FSTfG A TJ OX . From the first it was intended'to conduct two series of investigations, the first into the regenerateion and rate of growth of the rimu tree, and the second into tin l possibility of' establishing exotic conifers on the ei t-over nusli country. The Canterbury School of Forestry was entrusted with the first investiations and observations of planting have been proceeding for the past seven years, but lately since the Governent introduced its measures for special economy, the area has become known as the Ross road plantation. During these seven years the St : ate Forest ‘Service has undertaken a Targe amount of experimental work in the planting of exotic trees. Various species have been tested on various ] sites, including tbe insignis, pOnderosa, and Corsica pines, Douglas fir, Lawson Cyprus, macrocarpa, western red cedar, 'and a variety of eucalypts ' and broad-leaf trees. Some -species -have made^>good««:growth., in special site conditions, but certain swampy sites, especially those contain ing a hard pan, have proved rather hostile to the establishment of exotic trees. The conifer that has seemed to show the greatest promise is the I western rod ced'ar (Thuja plienta), This tree is at present thriving on a variety of sites, both in the open and Interplanted among tlie thinner types of native bush. Indeed the results obtained from it have been so encouraging that further planting is to be done during the current (Season, THE WOODSTOCK NURSERY. Tlie young trees for exotic planting are raised in a special misery at Woodstock, a few miles lawny on the banks of the Hokitika river, and here, too, the conditions are very favourable for the raising of the western red cedar. Sample plots for periodic remeasurement have been laid down in all the blocks, and tlie results of the yearly measurement should indicate in the future the exotic trees which are likely to flourish in the cut-over bush country of the West Coast. Concurrently with the work of the State Forest Service, the Canterbury School of Forestry, under Mr C. E. Foweraker and. Air F, E. Hutchinson, has been carrying out a series of interesting observations on the growth and regeneration of the chief native timber tree —the rimu, METHODS OF OBSERVATION. Before 1927 a number of general, qualitative observations have, been made in the bush and the main, general facts of regeneration, composition, and life-history of the various forest types has been recorded. In 1927, however, a series of quantitative observations a large number of sample plots were laid down of sixes varying from one-quarter of a square chain to one or two acres. These plots contained rimu trees of all 'ages, from seedlings, to over-mature trees, They were nil carefully pegged and tied in by an accurate survey to permanent survey monuments, so that their location was fixed for all time.

Every sample plot had its disinguishing number, and every riinu tree within it was tagged with a brass t ! ag. In the case of the larger trees, a tag was fastened to each trunk with a copper nail. For the. seedlings and small saplings, it was affixed to a small stake planted nearby. The smaller plots were intended for the measurement of seedlings and saplings, while the larger plots contained trees of all sizes. Each tree was given a number, and this was punched on to its respective fag. The seedlings and saplings have had their height growth measured and general condition noted from time to time, while with the larger trees a record was taken of the diameter at breastheight and the height .as determined by an Abney level.

REMEASUREMENTS IN 1932. The whole series of trees was carefully measured during 1927-28, and it is intended to make the first complete re-measurement in 1932-33, when me result of five years’ growth will be seen. In this way it is hoped to obtain a complete series of measurements of the growth of rimu trees of all ages, Iroin seedlings to veterans. From the data thus obtained the' actual volume increment will be measured. Sample plots were also laid clown in different types of country—in virgin forest, and in various kinds of cutover and burned bush laud—to establish data of the actual regeneration of rimu as indicated by the seedlings appearing in such areas. These areas are annually recounted and checked, all the seedlings within them being carefully marked with pegs. While it is to o early yet to make any definite statement on the rates of growth and regeneration, the indications during the past lew years have been most encouraging. Rmu seedlings are appearing throughout the ’areas and in many cases the number of them seems to indicate the possibility of a completely-stocked rimu stand on some of the cut-over areas. The few remeasurments of height .and diameter that have been made indicate too tliat rimu is a much faster growing tree than was supposed Actual quantitative results 'are, of course, not yet advisable at this stage to quote provisional results. PROBLEMS OF MANAGEMENT. There are considerable difficulties in the regeneration and general handling of native hush but it is confidently expected that these can be overcome, One difficulty arises from the fact that the rimu tree is of two sexes—one male, producing pollen; and the ether female producing s'-’eds. Far’v investigations showed that the distribution of the sexes was about equal and that in a state of Nature a mature female tree was within pollinating distance or n male tree. Any system of regeneration would therefore require both male and female trees to be retained on an area In other words an isolated female tree at too great distance from a male tree would be unlikely to produce fertile seed. Investigations are now being made of a system of , management whereby mature bush that is being logged over may not be injured unduly and the young growth already there may have the chance to develop to maturity. That is to say. a silvicultural system and a proper scheme oi forest management for rimu bush is essential to its permanency as a timber-producing proposition. So far no insfUT'T'able stacles have been found, and it. is confidently expected that the liinu-bush in Westland may be made ;a permanent timber-producing area.