Corrigendum to NZJFS20(3), 257-267: Water potential and subsequent growth of Pinus radiata seedlings: Influence of lifting, packaging, and storage conditions.

The paper which this Corrigendum refers to is available here: Balneaves, J. M. and M. I. Menzies (1990). "Water potential and subsequent growth of Pinus radiata seedlings: influence of lifting, packaging, and storage conditions

Review of "Process modeling of forest growth response to environmental stress" by R. K. Dixon, R. S. Meldahl, G. A. Ruark and W. G. Warren.

Review of "The pines of Mexico and Central America" by Jesse P. Perry Jr.

Composite wood products based on Pinus radiata D. Don 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 vapour boron 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.

The data obtained from studies of penetration of methyl bromide gas into "green" and dry Pinus radiata D.Don sapwood were used to calculate the likely minimum "concentration : time" products at various depths into the wood. By largely graphical methods it was demonstrated that there is a curvilinear gradient into green timber and a linear one into dry wood. In the former, this gradient is such that it is not practical to achieve useful insecticidal doses much beyond a depth of 100 mm in green material using conventional tent fumigation techniques.

From a stand of 25-year-old Pinus radiata D. Don, 183 4.8-m-long logs 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; beforeplaning 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 relationship 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.

Wood properties were examined in 50 trees of Pinus radiata D. Don growing in Kaingaroa Forest in the central North Island of New Zealand. The stand was selected as "typical" of current silvicultural regimes and as being at the lower end of the age range for expected rotations of this species. Average whole-tree wood property values were determined from discs cut at the butt and the top of each log. Assessments were also made of compression wood, and within-tree variation in tracheid length and spiral grain.

Generally, the wood property values were similar to previous studies and to predictions for trees of this age grown in the region.

Spiral grain measurements were made on wood disc samples from fifty 25-year-old trees of Pinus radiata D. Don grown in Kaingaroa Forest in the central North Island of 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°. 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 point to 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.

A stem taper model involving a high-order polynomial for plantation Pinus caribaea Morelet var. hondurensis Barrett & Golfari (Caribbean pine) grown in Queensland was fitted in three 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 two principal components were then modelled using total height and diameter at breast height as the independent variables. In the third stage, total height and diameter at breast height under bark were modelled in terms of predominant height, and diameter at breast height 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 diameter at breast height.

The maximum average diameter bias for the final model, using predominant height and diameter at breast height over bark as predictive variables, was 2.5 mm. The average tree volume bias, based on coefficients modelled using predominant height and overbark diameter at breast height, was 0.13%. Apart from its accuracy, another advantage of this model is its ability to accommodate taper changes with tree size.

Bracon phylacteophagus Austin (Hym:Braconidae) was first established in New Zealand in 1988 as a biocontrol agent for the introduced Eucalyptus leaf-mining sawfly Phylacteophaga froggatti Riek (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 more than 1 year the sawfly population collapsed.

Simulated sampling 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 aberrant estimates based on small sample sizes are revealed.

Soils collected from eight locations under exotic conifers and adjacent undeveloped grasslands in the montane zone of the eastern South Island were analysed chemically to examine the hypothesis that conifers increase the availability of nutrients, especially phosphorus, in topsoils. Olsen 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. Increases were smaller under stands on hygrous high-country yellow-brown earths of the Canterbury region, but these soils were characterised by large increases in mineralisable nitrogen and sulphate-sulphur. Mean total phosphorus levels were not significantly affected by the presence of conifers, but organic phosphorus levels were lower under the conifers than under the adjacent grasslands and inorganic phosphorus levels were higher. Soil pH declined under the conifers, the decline being greater in Mackenzie soils than in the Canterbury soils. The decline in pH was accompanied by an increase in exchangeable aluminium. Bray-2 extractable potassium and magnesium levels were higher under the conifers than under grassland in the Mackenzie soils, but were lower under the conifers in the Canterbury soils.

Lolium perenne L. (ryegrass) and Trifolium repens L. (white clover) grown in a glasshouse experiment on soils collected from under both vegetation types responded positively to the elevated mineralisable nitrogen (ryegrass) and available phosphorus (white clover) levels. Foliar analysis of native shrubs persisting under young stands at two sites in Canterbury revealed higher concentrations of nitrogen, phosphorus, potassium, iron, copper, and at one site, zinc and manganese, than in shrubs growing in the adjacent grassland. At both sites, boron concentrations were substantially lower in one shrub species.

Mineralisation of organic matter by the pines appears to be the major mechanism for nutrient enrichment of topsoils under pines 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.

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 (Le., the larger seedling was always 2 weeks ahead of the smaller seedling). The RGR technique eliminated such size-related growth differences when growth exhibited an exponential pattern: y = k + e ^b+ct (where k=0, t=time, and b and c are constants). The 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. Various examples are given to show that RGR usually declines seedling size increases during the first 5 months after germination. Where the RGR value is a function of size, the RGR method of analysis is not suitable for eliminating growth differences related to seedling size.

Scions from selected Pinus radiata D. Don trees were grafted on to open-bed-grown seedlings. 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 Forest Research Institute nursery. Suspected early graft incompatibility affected the quality of the cutting material produced so that strike rates of cuttings taken from 1-year-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 this 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 years of field ortet selection. This is 1 year longer than if grafts were used but only half the present 4-year period required to produce rooted cuttings, and avoids the long-term problems associated with graft incompatibility.

A change in New Zealand's climate, because of the increase in "greenhouse" gases in the atmosphere, may affect the productivity of Pinus radiata D. Don through increased wind damage, more severe infection by fungal pathogens, and areas becoming too dry or too wet for satisfactory growth. The current P. radiata improvement strategy is well suited to maintain genetic improvement in a changing environment. Future research should consider planting identical field trials at particular sites several years apart, and planting trials at and beyond the current extremes of climate. Research on alternative species should be encouraged.

Review of "Forest producsts trade: market trends and technical developments" by Jay A. Johnson and W. Ramsay Smith.

Reply to comment on "Structural root morphology and biomass of three age-classes of Pinus radiata".

Letter to the Editor - Comment on "Structural root morphology and biomass of three age-classes of Pinus radiata".

The yields of char, tar, and non-condensible gases from the pyrolysis of Pinus radiata D. Don bark were measured. Pyrolysis of bark, on a small preparative scale using an airacetylene flame, gave 48% char with ash content 3.5% (mainly aluminium, calcium, potassium, and silica), and recovered tar in 7% yield (on oven-dried bark equivalent). The major components of the pyrolysis tar were catechol and 2-methyl-catechol.

An exterior exposure trial was established in Rotorua 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 D. Don plywood were erected vertically on a test face with a northerly aspect. The trial included three adhesive types, five preservative treatments, and four surface/exposure treatments. Panels were tested prior to exposure and then after 1, 2,4, and 12 years.

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, declined significantly over time in plywood with veneers treated to 5 kg CCA/m³. This decline occurred in fully exposed panels and also in panels stored indoors. The uncoated melamine-urea formaldehyde panels had failed completely after 12 years 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 years was difficult because of the differences in wood failure values obtained from the tension shear test and the chisel test.

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. World wide the 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 reveals that they are niche ones, and frequently the lengths of clearwood actually required by these markets are quite short. Some markets, notably mouldings and veneers, require longer lengths. Many users such as small furniture/joinery manufacturers could use short length clears but are reluctant to shift 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 realise its investment in pruning. Standard blanks may well be the best way to utilise 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 way of producing clears will depend upon the targeted niches and the suppliers' ability to modify the customers' preference for long lengths.

The initial stocking trial, 19 years old at the time of assessment, was located in Rotoehu Forest, and incorporated genetically improved stock (with a Growth and Form factor of 13) and unimproved stock (GF3). It was planted at six levels of initial stocking from 250 to 1500 stems/ha, and thinned to 250 stems/ha. Results of the evaluation were adjusted for bias due to microsite.

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 (p>0.05) in mean diameter at breast height (dbh) 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 with increasing selection ratio, the highest selection ratio tested (6:1) being worth $4,000 (29%) more at age 19 than planting at final stockings. This difference is expected to increase to $5,900 (23% more) at age 25 and $8,200 (24% more) at age 30. GF3 genetic stock was less valuable (by $3,700/ha, or 21%) at age 19 than GF13 stock at the same 6:1 selection ratio, had a 1.8 cm smaller dbh, 1.3 m lower mean top height, 50 m³/ha less total volume, and was inferior in straightness. Although pruned volume was 13 m³/ha less, the difference was not statistically significant. GF 13 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, GF13 is expected to be $5,000 (18%) more valuable, and $5,800 (16%) more valuable at age 30, but this could be an under-estimate because there is some doubt as to the reliability of model projections for new breeds.

The apparent uptake of fertiliser phosphorus and the differential uptake of nitrogen at three sites in a Pinus radiata D. Don fertiliser trial were calculated by the difference between untreated plots and plots treated with 150 kg P/ha as rock phosphate or as superphosphate. Seven years after the fertiliser was applied, the treated plots contained approximately 10% of the applied phosphorus. A further 3% was present in the forest floor. The understorey contained very little phosphorus and the understorey in the treated plots contained very little more than in the control plots. The soils at the three sites differed markedly in their phosphorus retention characteristics (from 0 to 93 % phosphorus retention) but this appeared to have little effect on utilisation of applied phosphorus by the trees. At the site with the very low phosphorus retention, leaching of phosphorus seemed to occur. At the sites with the higher phosphorus retention, enhanced availability of phosphorus was restricted to the top 10 cm. Both the rock phosphate and the superphosphate treated trees contained similar additional amounts of phosphorus. We conclude that rock phosphate is as effective a fertiliser as superphosphate The difference in nitrogen content after phosphorus application was inconsistent. At two sites there were only small changes in nitrogen content but at the third site application of phosphorus alone caused a 41% increase in nitrogen uptake.

A progeny test of 25 parents mated in a series of five, five-parent, disconnected diallels was established on 11 sites chosen to represent all major site types for growing Pinus radiata D. Don in New Zealand. Statistical analysis of an assessment at age 9 years suggested that for diameter, the most important trait in the New Zealand tree improvement programme, genotype x environment interaction was important. However, genetic gains predicted for diameter for several regionalisation options, using multi-site index selection, suggested that regionalisation of seed orchards would increase the average genetic gain in diameter over all sites only slightly.

Further, many fewer than the full 11 sites were required for selection in order to capture essentially all of the predicted genetic gain for a national programme. Selection using the best site resulted in 90% of the maximum possible predicted gain, but the poorest site only 23%. Sites which were "very good" for selection had rapid growth, high phenotypic variance, and high repeatability of general combining ability (GCA) effects. Sites which were "very poor" for selection had slow growth, low variance, and low repeatability.

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 over 120 provenances of eucalypts drawn from over 60 species. The trial sites of Pakaraka and Kahuiti, planted in 1979, were re-assessed in 1991 after an earlier comprehensive measurement in 1984. On the basis of the latest data, larger-growing eucalypts suited to hillside plantings in this district are Eucalyptus regnans F. Muell., E. obliqua L'Herit, E. fastigata Deane et Maid.,E. botryoides Sm., E. botryoides x saligna Sm., E. nitens (Deane et Maid.) Maid., E. fraxinoides Deane et Maid., E. sieberi L. Johnson, E. delegatensis R.T. Bak., E. viminalis Labill, E. globoidea Blakely, E. smithii R.T. Bak., and E. oreades R.T.Bak. Suitable smaller stature species are E. amygdalina Labill., E. cordata Labill., E. brookeriana A.M.Gray, E. radiata Sieb. ex DC., E. cladocalyx V. Muell., E. pulchella Desf., E. agglomerata Maid., and E. nitida Hook. f. The larger trees would serve best in conservation/production/agroforestry regimes, the smaller at wider spacings in conservation/pastoralism regimes. Provenance comparisons within species generally support the findings of more extensive genetic improvement trials focused on the eucalypts with most potential for timber production.

An area in Kaingaroa Forest containing unthinned adjoining blocks of the same age of pure Pseudotsuga menziesii (Mirb.) Franco (Douglas fir), Larix kaempferi (Lamb.) Carr. (Japanese larch), and Larix decidua Miller (European larch), and of mixtures of Douglas fir with Japanese larch, and Douglas fir with European larch was studied for growth trends over a 13-year period from age 19 to 32 years. Two thinning treatments (unthinned control and thinned to 500 stems/ha at age 19 years) were tested in permanent sample plots established in the pure and the mixed blocks.

When Douglas fir was planted in mixture with Japanese larch on this site it became dominated and supressed by the larch species. However, when planted in mixture with European larch almost the reverse occurred, although the mixture could not be considered to be successfully self-thinning at age 32 years. When thinned at age 19 years, 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. Results from this study support the case that manual thinning to achieve a desired regime should remain the preferred management technique for Douglas fir in New Zealand.