Soil magnesium (Mg) levels corresponding to the critical foliar Mg level in radiata pine (Pinus radiata D. Don) of 0.06-0.08% (600-800 ppm) were investigated in a preliminary study of eight trees on the Ahaura stony fine sandy loam in the Inangahua Depression, South Island. Of the four measures of soil Mg studied, (1) total, (2) HN0₃-soluble and (3) HCl-soluble, but not (4) exchangeable, were found to give significant correlations with foliar Mg levels. HN0₃-soluble and HCl-soluble Mg appear to be potentially the most useful. Critical soil levels corresponding to the critical foliar levels are approximately 300 ppm for HN0₃-soluble Mg and 500-600 ppm for HCl-soluble Mg. Further studies will assess the applicability of these values both to young stands and older stands over a range of soil types.

Growth rates and intrinsic wood properties were examined in 50 trees which had undergone severe silvicultural treatments. Wood density was measured with beta-ray densitometer, using samples from 10 mm increment cores. Tracheid lengths were determined from whole-ring macerations of the same samples.

Stem diameter growth was reduced by pruning treatments, but the effect was short-lived even in the absence of thinning. Pruning tended to increase mean wood density by up to 7% for 2 to 3 years after treatment. These effects are of little technological significance.

An inverse relationship appeared to exist between ring width and tracheid length, and hence thinning resulted in reduced tracheid length values—the effect this on strength needs to be considered with that of the higher proportion of corewood to be expected from possible shorter rotations.

Spiral girdling of young radiata pine (Pinus radiata D. Don) was used to study the anatomical changes in cambium as initials move into alignment with the girdle. Light and electron microscopy showed that cambial initials are capable of considerable plastic deformation, initiated primarily by differential growth in fusiform initials. Ray initials appear to play a passive role in developing spirality, but eventually respond to pressures from the surrounding cambial elements. The frequency and directions of pseudotransverse divisions were also examined, but realignment of the daughter cells of multiplicative division could account for only a minor part of the grain angles that developed. It is believed that cytoplasmic stress arising during differential growth in fusiform initials determines the orientation of the mitotic spindle during anticlinal division. The spindle axis, in turn, determines the. direction of chromosomal separation at anaphase, and the direction of pseudotransverse division. Hence, the direction of pseudotransverse division is thought to be symptomatic of differential growth rather than a primary cause of spiral grain. Analysis of the component features of cellular reorientation gives support to the concept of a symplastic pathway being the route of auxin movement through cambial cells.

Green Douglas fir sawn timber was dipped in an aqueous solution containing 0.6% sodium pentachlorophenate and 1.8% borax pentahydrate, within 48 hours of conversion. Almost complete control of decay and partial control of sapstain over a storage period of one year was obtained. Packets tightly wired for export and dipped for 30 seconds in this solution were protected from fungal attack equally with those where the individual pieces were momentarily dipped before before block-stacking and wiring.

Wounds similar to those made by Platypus beetles were drilled in living red beech (Nothofagus fusca (Hook, f.) Oerst.) trees. Sapwood discolouration associated with such wounds was found to be due to the presence of microorganisms. Results also suggested that this discolouration is a tree response to toxic substances produced by micro-organisms.

In a low-stocked, unpruned and unthinned radiata pine (Pinus radiata D. Don) stand on malformation-prone scoria soils, the proportion of dominants increased from 35% at height 5 m to 50% at 9.5 m, but had decreased to 37% by 12.5 m. There was some interchange of dominance; only 63% of the final dominants were dominant at all assessments. Some trees dropped in status to regain it later.

Of trees of acceptable form at 5 m only 49% were still of the same form and dominance by 12.5 m, yet the total number of such trees at 12.5 m was the same as at 5 m. This anomaly is explained by the unexpected result that half of the original terminally defective stems outgrew their malformation.

Experienced officers differed in their opinions of the best 400 stems/ha at height 5 m. Despite this and the subsequent interchanges of both dominance and malformation status, 35-40%? of the selected stems were still of good form by height 12.5 m. This suggests that these stands can be reduced to 500-600 stems/ha at the time of first pruning and still provide adequate selection for a final crop of 200 stems/ha.

These results suggest that current priorities in pruning selection are not correctly based. Dominance can be maintained by adequate thinning; leader malformation has an even chance of recovery; therefore, stem malformation, as it is permanent, should be the primary basis for selection. The condition of the leader should be the second basis and relative dominance the third.

Pruning of a second log length (in addition to a butt log) was carried out over 3030 ha of State plantations in 1959-70 but only over 0.4 ha in 1971-72. Change in log form following thinning and pruning and the potential of radiata pine (Pinus radiata D. Don) to be grown to 60 cm d.b.h. in 26 years on a site index of 29 m have recently been demonstrated. This, and results from grade studies, suggest that the profitability of second log pruning should be re-examined. Profits of $72/ha land expectation equivalent are made at 7% interest, after allowing costs of $39.5/ha for each of two pruning lifts of 5.5-8.5 and 8.5-11 m, for trees of the size and age given. Uninodal second logs should remain unpruned. Profitability is naturally sensitive to all cost, return and silvicultural variables.

Second log pruning of short rotation sawlogs is a special, simple case in which the comparison between pruned and unpruned logs of the same age is valid, as the rotation and other treatments stay constant. Pruning profitability should normally be calculated by comparisons with the most profitable alternative regimes.

In a 500 ha block of terrace rimu (Dacrydum cupressinum Lamb.) forest in Ianthe Forest, South Westland, 194 plots each of 400 m² were established systematically to determine growing stock and increment. The average growing stock was 309 m3 of rimu and 10 m³ of other merchantable species (mainly miro Podocarpus ferrugeneus G. Benn. ex D. Don) per hectare, but it was found that there was probably a serious shortage of striplings, saplings and poles if the forest was to be managed as a selection forest. The gross mean annual increment, determined from increment cores, was estimated to be 1.45m³/ha of rimu and 0.05 m³/ha of other merchantable species. Two plots, each of 2 ha, were remeasured after 5 years and found to have mean annual increments of 3.43 and 2.81 m³/ha, but it is likely that these plots are on sites which are of better quality than is typical of terrace forest. Because it is considered that the 500 ha block contains about 85% of the stocking of a fully stocked selection forest, it would be unwise to assume that this block, and probably most terrace forest, has a potential mean annual increment of more than 1.75m³/ha until more extensive remeasurements prove otherwise.

Wood density was studied in 18 clones of radiata pine (Pinus radiata D. Don) replicated within and between four contrasting sites.

Clonal repeatabiiities were high, generally 0.75 or greater, and it appears that the standard deviation of genotypic values is about 6-10% of the population mean. Notwithstanding appreciable clonal differences in the density gradient, clonal correlations were high between density in the first and second five rings from the pith.

Site effects were large, but not altogether consistent among different parts of the tree. Expression of site and genotypic differences was generally greater at breast height than higher up.

Clone-site interactions, although statistically significant, were minor, the most important involving a phosphate-deficient site and elsewhere. The clones which were severely distressed on this site showed a slightly greater density increase, in relation to another site, than the remainder.

Within sites density was very little affected by non-genetic differences in ring width, which accounted for less than 5% of the phenotypic variance at standard sampling positions.

Evidence for clonal relationships between density and growth rate in general is inconclusive. However, it appears that outside the first five rings there is a positive effect of height coupled with a negative relationship with diameter. This accords with mechanical considerations.

Seeds of radiata pine (Pinus radiata D. Don), from a wind-pollinated Cambria (California) stand and control-pollinated trees in New Zealand, were germinated under uniform conditions. The seedlings were grown in the Duke University Phytotron under 30 combinations of day and night temperatures ranging from 5° to 32°C. The experiment covered 1080 seedlings, i.e., 36 seedlings, 18 from each source, in each of 30 treatments. Half the seedlings were harvested at the end of 3 months and the remainder at 6 months.

Although the tallest 3- and 6-month-old seedlings had grown under warm day (20° to 29°C) and night (17° to 23°C) temperatures, the relative growth rates between 3 and 6 months showed that the older seedlings at cold night temperatures (5°C) were growing the fastest.

Growth of shoot, root and total plant dry weight and diameter was significantly greater at a 5°C night temperature at both times and for both sources. The effect of day temperature, except at the extremes of the range, was minor compared to that of a 5°C night temperature. A trend, particularly apparent from the relative growth rate data from 3 to 6 months, showed increasing growth at the cool night (5° and 11°C) and cool day (17° to 23°C) temperatures. The temperature regime affected also the distribution of growth within the seedling, with higher root/shoot ratios and lower height/diameter ratios being observed at the colder night temperatures. The Cambrian seedlings grew better than the New Zealand seedlings only at the high day temperatures of 32° and 29°C. The 6-month-old New Zealand seedlings were on average 12% larger than the Cambrian seedlings owing to differences in relative growth rates over the first 3 months, although the Cambrian seed was 13% heavier than that from New Zealand.

The temperature requirements for growth of radiata pine are compared with those of other species, and with the climate in its native habitat and in New Zealand.

Linear programming techniques can be used by industry to optimise the allocation of resources to processing units and to rationalise the distribution of production from these processing units to markets. Since transportation costs are a significant variable cost factor in wood-processing industries, linear programming methods are a valuable tool for assisting in the planning of the location and functional integration of individual plants. Although there is little published evidence of these procedures being adopted in New Zealand, it is apparent from this study that such objective approaches could be usefully applied to many of the location problems of major forest owners and wood-processors.

Evidence shows that lignification causes significant dimensional changes during differentiation of wood cells. Because lignin occupies sites in the cell wall similar to those occupied by water, the theory of anisotropic shrinkage can be used to deduce that compression wood tends to expand longitudinally during lignification. Consequently, large forces are generated on the underside of a leaning stem; with assistance from forces in tissue elsewhere in the cross-section, these cause reorientation movements. The characteristic mechanical properties of compression wood cells contribute to maximising their functional value in supporting the displaced tree, and in its reorientation movements.

Effects of beating on radiata pine (Pinus radiata D. Don) kraft fibre properties are assessed in terms of fibre dimensions, and surface and intrawall structure. Wood quality effects are discussed with reference to pulps and handsheets prepared from young, mature and compression wood, and earlywood and latewood samples.

Mature earlywood, latewood and composite pulps have similar handsheet properties except for elastic modulus and tear factor. Corresponding young wood pulps give greatly different paper properties. The range of young wood paper properties is associated with readily flattened earlywood fibres in which beating produces extensive intrawall dislocation and layer separation.

Compression wood paper properties vary with fibre dimensions and density in the same way as normal wood, except for stretch. Exceptionally high compression wood stretch values are associated with the unique intrawall structure of reaction wood fibres, i.e., spiral checking within the S₂ layer, absence of an S₃ layer and an anomalous S₁ layer.

Breaking length and scattering coefficient are affected by beating to similar extents which indicates that both parameters are equally affected by web consolidation and intra- and interfibre bonding. Apparent density, however, appears to be affected only by the nature of fibre packing within a sheet. Most paper properties attain maximum values after extended beating treatments. These maxima coincide with a scattering coefficient of about 150 cm²/g which indicates that maximum fibre flattening, and intra- and interfibre bonding occur at this scattering value. Any further decrease in the number of light interreflections is explained by the filling of interfibre voids with fines.

Seed production was studied in cones from 18 clones of radiata pine (Pinus radiata D. Don) replicated within and between four contrasting sites. At one site which was phosphate-deficient, number of full seeds per cone, along with cone volume and mean seed weight, was about one-third less than elsewhere. Empty seeds, although never completely absent, were prevalent only in occasional cones. Such cones were common at the phosphate-deficient site, but were not a consistent feature of particular clones. All clones showed inherently high fertility within cones.

There was indirect evidence of a high incidence of ovule abortion: firstly, number of seeds per cone showed much more non-genetic variability than number of scales, and secondly, within-clone correlations between these two characters were not high. Such ovule abortion is believed to resemble conelet drop, which was prevalent within the experiment, in being often not caused by inadequate pollination.

Almost without exception the cones contained totals of 40 or more seeds, suggesting that satisfactory cone development is related to a threshold frequency of either ovule abortion or ovule survival.

This paper reports the assessment, three yr after planting, of a trial designed to examine the effect of the age of parent ortets of radiata pine (Pinus radiata D. Don) on the growth of vegetative propagules taken from them. Seedlings were compared with grafts made from ortets aged 6, 15, 25, 43 and 66 yr, and cuttings rooted from ortets aged 6, 10, 19, 23 and 43 yr at the start of the trial.

A number of parameters were assessed and, after necessary covariance adjustments, it was shown that juvenile propagules (seedlings, and grafts and cuttings from six-yr ortets) differed widely in both growth rate and form from mature propagules (grafts or cuttings from ortets aged 19 yr and upwards). There were significant differences between the juvenile groups, and there were intermediates between the juvenile and mature groups; but there were few differences between the mature propagules. These data are interpreted to suggest that the process of maturation or phase change occurs progressively during the early years, but is a finite process which does not continue through the life of the tree.

The implications of these findings to a programme of plantation establishment with cuttings, combined with genetic improvement, are examined; and it is concluded that, at least in the early stages of the rotation, the use of vegetative propagules may mean a loss in stem volume of up to 40% compared with seedlings. This must be offset against improvements resulting from the reduction of defects associated with the juvenile habit.

Gas exchange measurements of photosynthesis, respiration, and transpiration of radiata pine (Pinus radiata D. Don) seedlings have been used to study diurnal patterns and responses to temperature, subjection to drought, flooding, and decapitation of the shoot.

The diurnal patterns of net photosynthesis and transpiration in a controlled environment showed a rapid initial increase followed by a slower increase to a maximum after about three hr of illumination. This was followed by a gentle decrease, consistent with an increasing leaf water deficit, until the end of the photoperiod. This diurnal pattern exhibited by plants grown in a controlled environment should be taken into account in planning short term experiments.

The effects of temperature included an increase in maximum photosynthetic capacity between 11° and 23°C, possibly due to effects on the enzymatic reactions, and a depression at elevated temperatures attributed to disorganisation of the photochemical systems.

Repeated cycles of droughting produced expected stomatal responses and less obvious cumulative effects on gas exchange, some of which seemed non-stomatal. Plants which were flooded behaved in most respects as though suffering a water deficit.

Gas exchange of the shoots of seedlings severed from their roots suggested that whilst subsequent transpiration was much affected, photosynthesis was only slightly affected.

Morphological characterisation of sika deer is attempted by using a discriminant function analysis based on autopsy data from a mixed population of sika and red deer. There is evidence of hybridism between the two species. The history of liberation and dispersal from the northern Kaimanawa Mountains is illustrated by two dispersal maps based on sighting records and roar data. Spread was predominantly through shrubland or shrubland/forest ecotones. Dispersal rates varying from 0.6 to 1.5km/yr are estimated for the period 1905-30, and then for decades to 1970, showing an acceleration after 1950 (possibly due to human activity pushing the deer westwards into indigenous forest regions).

The growth patterns of silver beech (Nothofagus menziesii (Hook, f.) Oerst.) in natural forest conditions in northern Fiordland, New Zealand, are described.

Growth rates differed significantly between some forest associations. The reasons for this were related to site quality (particularly below 610 m altitude) and the effects of altitude. Growth rate was compared for three altitude zones and found to decrease at higher altitudes.

Growth rate/diameter relationships for trees growing on < 610-m-altitude slopes and terraces followed a negative exponential curve to reach a maximum growth rate at about 40 to 50 cm diameter at breast height (d.b.h.). Trees from > 610-m-altitude slopes showed a steady increase in growth rate to a maximum at about 40 cm d.b.h. There was no reliable evidence for a decrease in growth rate in larger diameter stems.

Diameter/age relationships showed that at any given diameter, terrace trees were youngest and high altitude trees oldest. The differences in age increased with increasing diameter.

At high altitudes, a greater proportion of large trees (>30cm d.b.h.) fell into the 30 to 70 cm d.b.h. size classes than at low altitudes where there were more stems >

Two-year aerial spray trials of copper-based fungicides were undertaken to control Dothistroma needle blight in heavily infected, young Pinus radiata D. Don. Two applications, 3 months apart, of cuprous oxide at 2.24 kg copper metallic equivalent in 56 litres water per ha (2 lb/5 gal/ac), provided adequate control for 2 years. Over 1 year a single application in December was almost as effective as the double application, but the single application in February was only half as effective as the December application. Evidence suggests that the effect of the copper fungicides was independent of the initial disease intensity.

Fungicide formulation in water or oil made no difference to its effectiveness, nor did diluent dosage rates of 56 and 112 litres per ha (5 and 10 gal per ac). A summer spraying oil had no effect; cuprous oxide at 1.12 kg copper metallic equivalent per ha (1 lb/ac) was effective, but less so than 2.24 kg (2 lb).

There were appreciable residues of copper on pine needles after 2 months and 254 mm (10 in.) of rain, but not after 3 months and 432 mm (17in.) of rain.

Cone samples were collected from a trial with 18 clones of radiata pine (Pinus radiata D. Don) replicated within and between four contrasting sites, of which one was deficient in soil phosphate. The cones were assessed for length, breadth, volume, length : breadth ratio, number of scales, and mean seed weight. One objective was to evaluate the influence of site on cone characters and on taxonomic information that they afford.

Cone dimensions, number of scales, and mean seed weight all showed significant clonal repeatabilities within sites (0.35 to 0.85, P < 0.001), confirming the genetic control of these characters. Cone volume and mean seed weight were about one-third less at the phosphate-deficient site than elsewhere. Number of scales varied little between sites. The only important clone-site interactions appeared to reflect differences between clones in response to the phosphate deficiency.

Cone size and seed weight, although differing widely between natural populations, are of restricted diagnostic value as a guide to the ancestry of stands in New Zealand, owing to their environmental plasticity.

Two increment cores were taken at breast height from 50 trees of Pinus contorta Dougl, on each of 16 sites, to assess variations in outerwood density between trees and between sites. On the basis of this preliminary survey five trees, stratified with respect to stem diameter and wood density, were felled on each of eight selected sites for detailed examination of wood physical properties, resin content and tracheid length. Most attention was directed towards two "green strains" (of subspecies contorta Critchfield) derived from Cpt 2 Waiotapu Forest (origin unknown) as one seed source, and from seedlot R26/26 (Manning Seed Co., Washington) as the other, though other stands of the same subspecies and of "yellow" strains (subspecies murrayana Critchfield) were also examined. No other seed source is producing wood with properties markedly superior to that of the two preferred "green" strains. Of the two, the "Manning green strain" is producing consistently denser wood than the "Waiotapu green strain", and the wood is not inferior in other respects. In general the wood density of trees grown on sites with low mean annual temperatures is lower than that produced on warmer sites: densitometer studies show that this is mainly due to the production of low density latewood on cold sites. The resin content of P. contorta is rather high (average more than 3%) which may restrict its use for groundwood pulp. In other respects its wood properties are those of a general-purpose softwood very suitable for sawn timber or chemical pulping.

It has been generally considered that the incidence of graft incompatibility in Pinus is low compared with other genera. This paper cites an example of a sudden increase to more than 50% incompatibility in a 14-year-old seed orchard of Pinus radiata D. Don. The types of incompatibility present are examined and the implications for New Zealand's clonal seed orchard programme are discussed.

The factors affecting daily transpiration rates of individual trees are briefly reviewed, together with models of their relationship. Using experimental data for ramets of seven radiata pine clones growing in volcanic sandy loam, the following equation is constructed:

t/E = 25.036 — 33.93 exp (0.07(5 —S)) + 1.311/E — 0.0074(S —5)²

for which t is daily transpiration per tree in ml per g o.d. wt of foliage; E is open-tank evaporation in cm/day; and S is soil moisture content expressed as percentage of soil o.d. wt. This equation accounts for 53% of the overall variation. The residual variation may be reduced by a further 11% if coefficients are fitted to the individual clones. Differences of transpiration rates between clones are highly significant.

Comparative data for soil water potential and needle pressure potential are also presented.

Seedlings of radiata pine (Pinus radiata D. Don) growing in a temperature-controlled greenhouse at day/night temperatures of 26/23°C were pre-conditioned for 6 weeks prior to transplanting, by one of the following watering regimes: D, watered daily; W, weekly; or F, 2-weekly. After transplanting, 24 seedlings of each pre-conditioning treatment were placed into one of the following environments: (a) the pre-transplanting environment, but watered every 8-10 days; (b) artificially-lit cabinet at 23°/20°C (day/night temperatures), and watered every 10-14 days; (c) as (b), but watered every third day.

After transplanting, the D seedlings exhibited high rates of transpiration which fell to about 10% of the original value after 2 days. When the seedlings were actively transpiring, their stomata remained wide open even though the plants were experiencing increasing water deficits. The F and W seedlings on being transplanted, opened their stomata only partly, and thus initially used less water than the D seedlings, and developed smaller water deficits. In the pretransplanting period D seedlings had significantly higher rates of stomatal and cuticular transpiration than the W plants which in turn had higher rates than the F plants, but 3 weeks after transplanting, this order was reversed. Eighteen days after transplanting, the F seedlings had more new root growth than the W seedlings. The D seedlings had the least new root growth. These differences in root growth had disappeared 40 days after transplanting.

The biology of Xyleborus saxeseni (Ratz.) in New Zealand is described and compared with that reported from the Northern Hemisphere. The life cycle occupies a minimum of 8 weeks with emergence most probable between September and February. Brood size and sex ratio vary greatly with a high proportion of nests producing no males. The significance of virgin females in nest failure is discussed. In the central North Island two and possibly three generations occur annually. Emerging adults attack radiata pine (Pinus radiata D. Don) logs one week after felling.

Flight never occurred before noon. During mid-afternoon, provided that temperatures exceeded 21°C beetles flew readily, but above 32°C flight ceased. Following flight exercise the initially positive phototropic response of the beetles was reversed. Thirty-one indigenous and exotic tree species are recorded as hosts; the insect was very selective of the condition of host material it utilised.

The composition and structure of the forests and scrublands of South Westland were recorded at 834 sample points. The vegetation at each was classified into associations using a combination of Sorensen's "k" index of similarity, and a multi-linkage cluster analysis. The associations were related to habitat and the distribution of each determined.

Fourteen associations of which 10 were subclimax in nature were recognised; one included all the sub-alpine scrub, three were in high altitude silver beech forest, three were in mid altitude silver and mountain beech forest, and three were in low altitude silver beech forest. Four seral forest associations were recognised. These were variously dominated by lacebark, Olearia species, fuchsia, wineberry, kamahi, and pate.

The influence of red deer on the forests and scrublands was examined. Stand structure was used to determine the degree of modification and the susceptibility of the vegetation to damage from browsing. Browse indices were used to determine current ungulate use.

The associations most susceptible to damage by red deer were shown to be the serai ones and the most susceptible catchments, the Turnbull, the Waipara, and the upper Arawata. The associations which have been most modified by red deer are those at low altitudes, especially in the Waiatoto catchment, and the least modified are those at high altitudes, particularly in the lower Arawata. Present use of the forests and scrublands is most pronounced in serai areas and on the mid and lower-mid slopes. It is least at high altitudes, in the sub-alpine scrub and upper forest, and in the vicinity of the low level terraces. The catchments currently receiving the greatest use are the Arawata and upper Waiatoto, while those receiving least use are the Turnbull and Okuru.