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NZJFS - Volume 21
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Fibre-based composites in New Zealand: past developments and future opportunities
Author(s) D. V. Plackett, J. M. McLaughlan and R. J. Burton ISSN 0048-0134 File size 4.0 mb Pages 246-255 Issue 2-3 Volume 21 This paper was originally presented at the IUFRO All-Division 5 Conference 'Better wood products through science', held at Nancy, France, 23-28 August 1992. Composite wood products based on Pinus radiata fibre have been made in New Zealand since the 1940s when a wet-process fibreboard plant was established in Auckland. Medium density fibreboard (MDF) production began in New Zealand in 1976 and the total capacity of the New Zealand MDF industry is now 465 000 m3 per annum or about 6% of worldwide capacity. In 1987 production began of a totally new type of board in which MDF surface layers are combined with a strandboard core in a steam-pressing operation. Two areas of research in progress at the New Zealand Forest Research Institute (FRI) are aimed at adding value to composites such as MDF. Firstly, research on dimensional stabilisation of MDF focuses on in-line chemical treatments of fibre. Secondly, the boron vapour treatment developed jointly by FRI and Imperial College of the University of London has the potential to improve the fungal, insect, and fire resistance properties of fibre-based composites. -
Penetration of methyl bromide into Pinus radiata wood and its significance for export quarantine
Author(s) D. J. Cross ISSN 0048-0134 File size 3.6 mb Pages 235-245 Issue 2-3 Volume 21 Fumigation with methyl bromide is a method used for controlling insect pests in timber, and has been the regulation treatment in New Zealand since the first trials in 1959, for both exported and imported timber. Penetration of methyl bromide gas into 'green' and dry Pinus radiata sapwood test blocks (discs about 100 mm thick) was measured. The data were used to calculate the likely minimum 'concentration : time' products at various depths in the wood. It was demonstrated that there is a curvilinear gradient of methyl bromide penetration into green timber and a linear gradient into dry timber. For green timber the gradient is such that it is not practical to achieve penetration of methyl bromide in doses large enough to ensure death of insect pests such as Sirex noctilio much beyond a depth of 100 mm using conventional tent fumigation techniques. -
Utilisation of 25-year-old Pinus radiata. Part 2: warp of structural timber in drying
Author(s) A. N. Haslett, I. G. Simpson and M. O. Kimberley ISSN 0048-0134 File size 2.6 mb Pages 228-234 Issue 2-3 Volume 21 One-hundred-and-eighty-three 4.8-m long logs from a stand of 25-yr-old Pinus radiata, in Kaingaroa Forest, New Zealand, were individually measured and sawn to 100x50-mm framing timber. After high-temperature drying, warp measurements were related to the individual log characteristics. Twist was the major form of degrade; before planing 36% of the lengths had excessive twist, and rejection from Framing 1 grade was 28%. Twist was most strongly related to log diameter, with corewood portion and spiral grain being the contributory factors. Twist also increased with log height class. Gauging halved the incidence of twist rejection. The relation between corewood proportion and twist, and its effect on rejection could be incorporated into current stand growth models, thereby extending the profitability modelling capability of models from green sawn timber through to the final dry product. -
Utilisation of 25-year-old Pinus radiata. Part 1: wood properties
Author(s) G. D. Young, D. L. McConchie and R. B. McKinley ISSN 0048-0134 File size 4.0 mb Pages 217-227 Issue 2-3 Volume 21 Data are presented on the volume and wood properties (heartwood and corewood content, incidence of compression wood, basic and green density, moisture content, log grades, resin content, dimensional shrinkage, tracheid length, bark percentage and spiral grain) of 50 Pinus radiata trees in a 25-yr-old stand in Kaingaroa Forest in central North Island, New Zealand. The stand was selected as typical of current silvicultural regimes and was at the lower end of the age range for expected rotations; it had been high pruned and thinned to a final crop of 350 stems/ha. Sample discs were cut from the butt and top of ends of a 6-m butt log from the pruned trees and 4.9-m logs from the unpruned lengths. The results are discussed in terms of intra-tree variation, corewood occurrence, and the incidence of defects. -
Spiral grain patterns in plantation-grown Pinus radiata
Author(s) D. J. Cown, G. D. Young and M. O. Kimberley ISSN 0048-0134 File size 3.8 mb Pages 206-216 Issue 2-3 Volume 21 Spiral grain measurements were made on wood disc samples from fifty 25-yr-old trees of Pinus radiata grown in Kaingaroa Forest in central North Island, New Zealand. Strong radial and vertical patterns were established, but there was also a major individual tree effect. The most pronounced deviations from vertical grain were in the inner 10 growth rings (corewood zone), where the left-hand angles averaged 4.7 deg . This amount of deviation is sufficient to cause significant problems in processing and marketing through drying degrade, strength loss, and movement in service. Outside this zone, angles were generally less and showed a higher proportion of right-hand spirals. The high average corewood spiral grain and the degree of variability between trees reinforce the possibility of a strong genetic component and indicate the need for a more efficient sampling method. Statistical analyses of the grain measurements indicated that there are large errors associated with predicting tree values from single ring assessments. It is feasible, however, to compare groups of trees (treatments, families, clones) using a relatively small number of ring measurements. -
Polynomial taper equation for Pinus caribaea
Author(s) P. J. Allen ISSN 0048-0134 Pages 194-205 Issue 2-3 Volume 21 A stem taper model involving a high-order polynomial for plantation Pinus caribaea var. hondurensis grown in Queensland was fitted in 3 stages. In the first stage, the stem profile for each tree was modelled using functions of under-bark diameter and height as the dependent and independent variables, respectively. In the second stage, the parameter estimates from these individual tree regressions were subjected to a principal component analysis. The first 2 principal components were then modelled using total height and diameter at breast height (d.b.h.) as the independent variables. In the third stage, total height and d.b.h. under bark were modelled in terms of predominant height, and d.b.h. over bark. Using these equations, and the inverse transformation from the principal components to individual tree regression coefficients, individual tree profiles and volumes were predicted from height and d.b.h. The maximum average diameter bias for the final model, using predominant height and d.b.h. over bark as predictive variables, was 2.5 mm. The average tree volume bias, based on coefficients modelled using predominant height and d.b.h. over-bark was 0.13%. Apart from its accuracy, another advantage of this model is its ability to accommodate taper changes with tree size. -
Spread of Bracon phylacteophagus a biocontrol agent of Phylacteophaga froggatti and impact on host
Author(s) W. Faulds ISSN 0048-0134 File size 3.1 mb Pages 185-193 Issue 2-3 Volume 21 Bracon phylacteophagus (Hymenoptera: Braconidae) was first established in New Zealand in 1988 as a biocontrol agent for the introduced Eucalyptus leaf-mining sawfly Phylacteophaga froggatti (Hym: Pergidae). By June 1991 the parasitoid had spread throughout much of the sawfly-infested area, and in most areas where the parasitoid had been established for >1 yr the sawfly population collapsed. -
Estimating stand weight - the importance of sample selection
Author(s) H. A. I. Madgwick ISSN 0048-0134 File size 1.9 mb Pages 180-184 Issue 2-3 Volume 21 Previously published data [Ovington, J.D.; Forrest, W.G.; Armstrong, J.E. (1968) In Symposium on primary productivity and mineral cycling in natural ecosystems (edited by Young, H.E.) 3-31] for a Pinus radiata stand consisting of 100 weighed trees were used in simulated sampling. One hundred samples of 20 trees were used to estimate the weight of each of 5 components (foliage, live branches, total branches, stems, and roots) using 5 estimation techniques (ordinary least squares, weighted least squares, regression after square root transformation, regression after logarithmic transformation, and the basal area ratio method). Both random sampling and stratified random sampling were used. The results showed that, in determining estimated stand component weights, sampling method and estimating techniques were of less importance than the sample of trees selected. There is a need for more work on the variables used to predict tree weight. Some problems arise with sequential sampling but it has the advantage that it reveals aberrant estimates based on small sample sizes. -
Increased nutrient availability in topsoils under conifers in the South Island high country
Author(s) M. R. Davis and M. H. Lang ISSN 0048-0134 File size 5.9 mb Pages 165-179 Issue 2-3 Volume 21 Soil collected from eight locations under exotic conifers and adjacent undeveloped grasslands in the montane zone of the eastern South Island were analysed. Oslen and Bray-2 extractable phosphorus levels were higher under the conifers than under adjacent grasslands at most sites, with the largest absolute increases occurring under older stands on dry soils of the Mackenzie Basin. Soils of the Canterbury region were characterized by large increases in mineralisable N and in SO4. Soil pH declined under conifers at all sites. Mineralisation of organic matter by the pines appears to be the major mechanism for nutrient enrichment of topsoils in the hygrous soils of Canterbury, but a different process, possibly transfer of nutrients from deeper horizons to the soil surface via nutrient uptake and litterfall, may be more important in the dry-hygrous soils of the Mackenzie Basin. -
Testing the hypothesis that mean relative growth rates eliminate size-related growth differences in tree seedlings
Author(s) D. B. South ISSN 0048-0134 Pages 144-164 Issue 2-3 Volume 21 Various hypothetical growth curves were used to evaluate the suitability of using mean relative growth rate (RGR) to compare growth when tree seedlings differ in initial size. Two seedlings were said to be growing according to the same basic growth curve if the only difference between the two growth curves was due to time (i.e. the larger seedling was always 2 weeks ahead of the smaller seedling). The mean RGR technique eliminated such size-related growth differences when growth exhibited an exponential pattern: y=k + eb+ct (where k=0, t=time, and b and c are constants). The mean RGR technique did not eliminate size-related growth differences under conditions where k was not equal to zero or when the growth curve was not exponential. Using previously published data (for Betula pendula, Citrus jambhiri, Gmelina arborea, Larix leptolepis, Liquidambar styraciflua, Picea glauca, Pinus cortina [P. contorta], P. elliottii, P. patula, P. radiata, P. sylvestris, P. taeda and Populus tremuloides) it was shown that mean RGR usually declines as seedling size increases during the first 5 months after germination. Where the mean RGR value is a function of size, this method of analysis is not suitable for eliminating growth differences related to seedling size. -
Propagation system for the production of rooted cuttings from physiologically mature Pinus radiata within 2 years of field collection
Author(s) J. C. Dorsser and T. Faulds ISSN 0048-0134 File size 3.1 mb Pages 135-143 Issue 2-3 Volume 21 Scions from 24 Pinus radiata clones were grafted in July 1987 onto open-bed grown seedlings at the Forest Research Institute (FRI) nursery, Rotorua, New Zealand. Small, medium and large scions from each clone were used. When the needles of the scions had elongated fully, half of the grafts of each clone were given additional fertilizer (NPKMg + trace elements at 200 kg/ha on 18 January 1988; foliar applications of 2% urea + 2% magnesium sulfate at 5000 litre/ha on 1 February and 1 March 1988). The resultant first-year grafts produced the material to be used as cuttings. The technique for rooting such material is based on a pre-treatment system developed since the 1960s at the FRI nursery. Suspected early graft incompatibility affected the quality of the cutting material produced so that strike rates of cuttings taken from 1-yr-old grafts were generally about half to two-thirds of those derived from repropagation hedges originally established with rooted cuttings. All but one of the 24 clones tested in the investigation produced rooted cuttings. The method described offers opportunities for establishing and updating of clonal repropagation and breeding archives as well as seed orchards with rooted cuttings within 2 yr of field ortet selection. This is 1 yr longer than if grafts were used but only half the present 4-yr period required to produce rooted cuttings, and avoids the long-term problems associated with graft incompatibility. Grafts from small scions produced fewer plantable stubs than grafts from medium and large scions. In order to obtain a sufficient number of rooted cuttings 3 to 4x as many medium- to large-sized scions as the number of rooted cuttings should be grafted. Further work is required to clarify the potential benefits of late-season fertilizer application. -
Climate change - implications for Pinus radiata improvement
Author(s) J. C. Grace, M. J. Carson and S. D. Carson ISSN 0048-0134 File size 4.6 mb Pages 123-134 Issue 2-3 Volume 21 A change in New Zealand's climate, because of the increase in greenhouse gases may affect productivity of Pinus radiata through increased wind damage, more severe infection by fungal pathogens, and areas becoming too dry or too wet for satisfactory growth. The current improvement strategy is well suited to maintain genetic improvement in a changing environment. -
Pyrolysis products of Pinus radiata bark
Author(s) T. D. Lomax, R. A. Franich and H. Kroese ISSN 0048-0134 File size 213.6 kb Pages 111-115 Issue 1 Volume 21 Pyrolysis bark from 25- to 28-yr-old trees of Pinus radiata yielded 48% char, 7% diethyl ether extractives (tar), 5% carbon dioxide and 1.3% methane. The ash content of the char was 3.5% (mainly aluminium, calcium, potassium and silica). The major components of pyrolysis tar were catechol and 2-methyl-catechol. Since catechol is a higher-value phenol (NZ $5000/t), pyrolysis of P. radiata bark may be of commercial interest. -
Properties of treated and untreated Pinus radiata plywood after 12 years' weathering
Author(s) J. M. McLaughlan ISSN 0048-0134 File size 865.6 kb Pages 96-110 Issue 1 Volume 21 An exterior exposure trial was established in Rotorua, New Zealand, in 1976 to monitor the performance of plywood panels in which the individual veneers were treated with a copper-chrome-arsenate (CCA)-type preservative prior to panel lay-up. Three-ply panels of 9.6-mm-thick Pinus radiata plywood were erected vertically on a test face with a northerly aspect. The trial included 3 adhesive types (phenol-formaldehyde, melamine urea formaldehyde and cross-linked polyvinyl acetate), 5 preservative treatments (none; plywood brush-coated with copper naphthenate; diffusion of green veneers to 5 kg CCA/m3 or 10 kg CCA/m3; and pressure treatment of veneers to 6 kg CCA/m3) and 4 surface coating/exposure treatments (uncoated and kept inside; uncoated and kept outside; painted and kept outside; and coated with water repellent and painted and kept outside). Panels were tested prior to exposure and then after 1, 2, 4 and 12 yr. Regression models were used to evaluate the effect of various treatment combinations. It was determined that wood failure, assessed from the failed surface of the tension shear test sample with lathe checks pulled to open, decreased significantly over time in plywood with veneers treated to 5 kg CCA/m3. This decrease occurred both in fully exposed panels and in panels stored inside. The uncoated melamine-urea formaldehyde panels had failed completely after 12 yr and delaminations occurred in panels of the other adhesive types with one failure occurring for the panel bonded with phenol formaldehyde and treated to 10 kg CCA/m3. Uncoated panels with CCA treatment generally fared less well than either the untreated or the copper naphthenate panels. Assessment of serviceability after 12 yr was difficult because of the differences in wood failure values obtained from the tension shear test and the chisel test. -
Market requirements for Pinus radiata clearwood: Implications of length specifications
Author(s) G. P. Horgan ISSN 0048-0134 File size 1.5 mb Pages 77-95 Issue 1 Volume 21 The term clearwood is defined as defect-free solid wood material of any length, so long as it is defect-free throughout the whole of its length. The world-wide market for clearwood is estimated to be around 59 million m3, of which the softwood component is some 22-23 million m3. Analysis of the markets for clearwood (with reference to New Zealand and to Pinus radiata in New Zealand) reveals that they are niche markets, and that frequently the lengths of clearwood actually required by these markets are quite short. Some markets, notably those for mouldings and veneers, require longer lengths. Many users, such as small furniture/joinery manufacturers, could use short length clears but are reluctant to move away from the use of long lengths because of the perceived loss of flexibility. New Zealand needs to develop markets for short length clears if it is to fully realize its investment in pruning Pinus radiata. Standard blanks may well be the best way to utilize this material and markets for such material are being developed. Standard blanks may also help suppliers overcome some of the concerns about the lack of flexibility implied by the use of short lengths. The most cost-effective ways of producing clears will depend upon the targeted niches and the suppliers' ability to modify the customers' preference for long lengths. -
Varying selection ratios (initial versus final crops stocking) in Pinus radiata evaluated with the use of MARVL
Author(s) J. P. Maclaren and M. O. Kimberley ISSN 0048-0134 File size 784.9 kb Pages 62-76 Issue 1 Volume 21 MARVL (Method for the Assessment of Recoverable Volume by Log types) was used to assess the results of a trial Pinus radiata at age 19 yr in the Rotoehu Forest, New Zealand. MARVL classifies each section of a stem and this is subsequently 'cross cut' into logs by a computer program, in such a way that single-tree value is maximised. Growth Model 22 and Height Model 34 were used to 'grow on' the stand to 25 yr and 35 yr old. The trial was established in 1970 to examine the effects of variation in initial stocking, and thus selection ratio, using genetically improved stock (with a Growth and Form (GF) factor of 13) and unimproved stock (GF 3). Initial stocking ranged from 250 (a selection ratio of 1:1) to 1500 stems/ha (a selection ratio of 6:1). All plots were selectively thinned to a final stocking of 250 stems/ha by 1977. Volume, height and diameter were measured at 19 yr old. There was an apparent site index differential of 1.6 m between selection extremes. This was attributed mainly to differences in initial stocking rather than to the effect of selecting taller trees. There was no significant difference in mean diameter at breast height (d.b.h.) due to selection ratio. The straightness of both the unpruned logs and the pruned butts was enhanced with increasing selection. By increasing selection ratio, total merchantable volume and pruned volume were substantially improved, owing to height differences and reduced malformation. Because of improved quantity and quality, there was an increase in stumpage value at age 19 yr with increasing selection ratio; the highest selection ratio tested (6:1) was worth NZ $4000/ha (29%) more at age 19 yr than planting at final stockings (viz. 250 stems/ha). The difference is expected to increase to NZ $5900/ha (23% more) at age 25 yr and $8200 (24% more) at age 30 yr. GF3 genetic stock was less valuable (by NZ $3700/ha, or 21%) at age 19 yr, had a 1.8 cm smaller d.b.h., 1.3 m lower mean top height, 50 m3/ha less total volume, and was inferior in straightness, than GF13 stock at the same 6:1 selection ratio. Although pruned volume was 13 m3/ha less, the difference was not statistically significant. GF13 stock at a selection ratio of 1.1:1.0 was equivalent in stumpage value to GF3 stock at a 6:1 selection ratio. At age 25 yr, GF13 is expected to be NZ $5000/ha (18%) more valuable, and NZ $5800/ha (16%) more valuable at age 30 yr, but this could be an under-estimate because there is some doubt as to the reliability of model projections for new breeds. -
Apparent phosphorus uptake and change in nitrogen content of Pinus radiata growing on soils of different phosphorus retention, treated with superphosphate and A-grade rock phosphate
Author(s) I. R. Hunter and J. A. C. Hunter ISSN 0048-0134 File size 707.4 kb Pages 50-61 Issue 1 Volume 21 The apparent uptake of fertilizer P and the differential uptake of N were measured in Pinus radiata stands at 3 sites in New Zealand. Two of the stands were 4 yr old (at Riverhead and Tairua) and one 7 yr old (at Waipoua) when P fertilizer was applied (as A-grade rock phosphate or superphosphate, both at 150 kg P/ha) in 1978. Urea (200 kg N/ha) and muriate of potash (80 kg K/ha) were applied in 1979 at one site which was in danger of becoming N and P deficient. Phosphorus retention characteristics of the soils were measured before treatment; at Tairua P retention was 93% in the topsoil of a clay soil derived from old deeply weathered volcanic ash; at Riverhead it was 48% in the top 10 cm of soil of a silty clay complex; at Waipoua it was 0% on a sand complex. Nutrient uptake of sample trees and by the understorey was measured in 1985 (in 11 and 13 yr old stands) and foliage analyses were done in 1980, 1982 and 1984. Uptake of P ranged from 7 to 12.5% and was not greatly affected by the phosphorus retention characteristics of the soil or the form of fertilizer. The forest floor contained a further 3% of the applied P. The understorey contained very little P with the amount in the treated plots very little more than that in the control plots. At the site with the very low P retention, leaching of P occurred. At the sites with the high P retention, enhanced availability of P was restricted to the top 10 cm. Both the rock phosphate and the superphosphate treated trees contained similar additional amounts of P. It is concluded that rock phosphate is as effective a fertilizer as superphosphate. The difference in N content after P application was inconsistent; at 2 sites there were only small changes in N content but at the third site application of P alone caused a 41% increase in N uptake. -
Genotype x environment interaction and optimal number of progeny test sites for improving Pinus radiata in New Zealand
Author(s) S. D. Carson ISSN 0048-0134 File size 1.1 mb Pages 32-49 Issue 1 Volume 21 A progeny test was planted in 1975 of 25 parent Pinus radiata trees mated in a series of five, five-parent disconnected diallels at 11 sites throughout New Zealand. Based on observations made at 9 yr old, analyses were carried out to assess the importance of the genotype x environment interaction (GE) for 6 traits (diameter at breast height (d.b.h.), stem straightness, branch habit, stem deformities, needle retention and occurrence of Dothistroma [Mycosphaerella] pini needle blight). The GE was only important for needle retention and d.b.h. Prediction of average genetic gain in diameter for various seed orchard regionalization options suggested that the resulting gains over all sites would only be slight. However, sites could in general be classified as good or poor, and it is concluded that use of a few good sites could yield as much gain as many poor sites. -
Eucalyptus species selection for soil conservation in seasonally dry hill country - twelfth year assessment
Author(s) B. T. Bulloch ISSN 0048-0134 Pages 10-31 Issue 1 Volume 21 Hillside stabilisation tree plantings are aimed at maintaining erosion-prone land in pastoral use. Species selection trials on drought-prone hillsides in the Wairarapa district (east coast, lower North Island, New Zealand) included >120 provenances of eucalypts drawn from >60 species. Larger-growing eucalypts suited to hillside plantings in the district are Eucalyptus regnans, E. obliqua, E. fastigata, E. botryoides, E. botryoides × saligna, E. nitens, E. fraxinoides, E. sieberi, E. delegatensis, E. viminalis, E. globoidea, E. smithii and E. oreades. -
Douglas fir, Japanese larch, and European larch in pure and mixed stands
Author(s) G. G. West ISSN 0048-0134 File size 322.3 kb Pages 3-9 Issue 1 Volume 21 An area in Kaingoroa Forest containing unthinned adjoining blocks of the same age of pure Pseudotsuga menziesii, Larix kaempferi and Larix decidua, and of mixture of Douglas-fir with Japanese larch, and Douglas-fir with European larch was studied for growth trends over a 13-yr period from age 19-32 yrs. Two thinning treatments (unthinned control and thinned to 500 stems/ha at age 19 yrs) were tested. When Douglas-fir was planted in mixture with Japanese larch it became dominated and suppressed by the larch, but when planted in mixture with European larch almost the reverse occurred, although the mixture could not be considerd to be successfully self-thinning at age 32 yr. When thinned at age 19 yr, Douglas-fir was more responsive in subsequent basal area growth than the two larch species. Thus, although early growth of Japanese larch was superior on this site, Douglas-fir is likely to be the most productive of the three species at final rotation.
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