The advantages of using tested clones in Pinus radiata D. Don forests were compared with current open-pollinated and control-pollinated seed orchard strategies. Clonal forestry shares with control-pollinated orchard strategies advantages of shorter plant production times, control of pedigree, flexibility of deployment, multiplication of valuable crosses, and efficient capture of additive genetic gains. It may have additional advantages in increasing uniformity, allowing clone/site matching, controlling growth habit, and capturing nonadditive genetic gains. However, a control-pollinated orchard strategy coupled with vegetative multiplication is currently proving to be more cost-efficient in establishing managed stands. Use of a clonal strategy requires evidence for greater economic gains.

This computer system provides information on each clone, maintains subculturing records over time, and enables comprehensive retrieval of information and error checking. The system has application in tissue culture laboratories handling a large number of clones and in the maintenance of gene-banks.

Embryos excised from mature Pinus radiata D. Don seeds were cultured in a small volume of a nutrient medium contained in a small aluminium capsule to form an artificial seed. The embryos developed with normal morphology, although not as large as those from natural seeds. All plants from artificial seeds formed roots in sterile soil. The growth of embryos placed radicle-down into the same agarified-medium was inferior in that the lengths of cotyledons, hypocotyls, and roots of the resulting plants were all markedly reduced. When embryos were cultured in liquid medium, development was aberrant, with virtually no root growth. Nutrient supply through the (natural) cotyledonary route appeared to be superior to entry through roots or hypocotyl.

A Pinus radiata D. Don cell suspension culture was developed from excised embryos using a Schenk and Hildebrandt medium modified by addition of 2.6 mM ammonium phosphate and 10 mM arginine hydrochloride. Initiation of the culture involved selection of initially rare meristematic cells from the dominant mass of differentiating cells with limited mitotic capacity. The chromosomally normal culture was found to be capable of long-term culture and amenable to quantitative growth experiments using dry-weight yields of suspension-cultured cells. Responses to nitrogen nutrients provided growth contour plots illustrating the interaction between ammonium and nitrate nutrients, with optimal growth in the vicinity of 3mM ammonium and 15 mM nitrate ions. Arginine was able to replace ammonia entirely, nitrate was necessary for good growth. Glutamine and asparagine were also growth effective, whereas little benefit was found with lysine, ornithine, or glutamate, and urea yielded an intermediate response. Higher levels of lysine (3mM), glutamate (10 mM), or casein hydrolysate (10 mM amino acids) resulted in growth reduction. The effectiveness of beneficial organic nitrogen supplements is ascribed to endogenous supply of reduced nitrogen for general cellular biosynthesis, and such supplements are considered unnecessary when inorganic nitrogen is optimised.

Systematic analysis of factors affecting proliferation of cell suspension cultures of Pseudotsuga menziesii (Mirb.) Franco (Douglas fir) derived from cotyledonary callus indicated that an initial inoculum of 30 mg dry weight per 10 ml medium resulted in optimal growth on a medium containing full-strength salts, 15/μM NAA and 500 nM BAP. Study of the effects of specific nitrogen sources on dry weight accumulation revealed that 30 mM KN03 as a sole nitrogen source was superior to ammonium and nitrate medium and produced a 120% increase in growth after 8 days in culture. Although a low level of ammonium (10 mM) when supplied as a sole nitrogen source could promote modest growth for 5 days, ammonium at either higher levels (30 and 50 mM), or for longer periods, was toxic. Cells grown on glutamate exhibited a pattern of growth similar to controls for the first 7 days, after which growth decreased sharply. When grown on glutamine (10, 30, and 50 mM) as a sole nitrogen source, cell cultures of P. menziesii grew rapidly with a shortened lag phase, and exhibited exponential growth rates approaching twice that of control cells grown on ammonium and nitrate.

The growth of microspore callus cultures of Picea abies L. Karst, was stimulated by weak fluorescent and red light as opposed to darkness. Putrescine (0.1 mM) was able to enhance growth in the dark. The effects of spermidine and spermine on growth were rather similar but root differentiation was stimulated by spermidine in blue, red, and fluorescent light, by spermine only in red light. Glutamine (500 mg/L) and a combination of it and casein hydrolysate (1000 mg/L) retarded growth and root differentiation. The root had a weakly developed central cylinder with tracheids. The microspore callus cells had normal ultrastructure. Accumulation of starch, plastoglobuli, and some weakly developed grana were characteristic of plastids. Greening of cultures was not observed in red light. Accumulation of secondary metabolites was very prominent, especially in the vacuoles of some cells cultured in blue light. The plastids in those cells were usually rather small and contained very little or no starch.

In March 1981, Weyerhaeuser Company established a field trial across five sites in coastal Oregon to test performance of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco plantlings derived from cotyledon explants through tissue culture. Main objectives of the trial were to (1) compare survival and growth of plants produced by different propagation techniques (stock types) from the same genetic material, (2) compare field performance of plantlings derived from select orchard families with that of plantlings derived from local wild seed, and (3) assess the effects of size and form at planting time on subsequent plantling performance.

After 5 years, survival in the stock-type trials was 91% for plantlings, 99% for seedlings, and 49% for rooted cuttings. In the larger family comparisons, plantlings exhibited 74% survival. Owing to smaller initial size and 1 early year of reduced growth, plantlings are now 11% shorter than seedlings but both have had the same height increment during the past 3 years. Rooted cuttings are only 66% as tall as seedlings. Plantlings derived from select families are significantly taller on all sites than those derived from wild seed, the best family being 27% taller.

Early plagiotropism in some plantlings reduced survival but had no effect on height growth. All plagiotropic tendencies disappeared by the third season in plantlings but continued to persist in the rooted cuttings. Poor rooted cutting performance probably reflected ortet age (8 years) and/or unsatisfactory culture environment.

The flooding of Picea sitchensis (Bong.) Carr. (Sitka spruce) cultures on hormone-free medium with water resulted in promotion of both apical extension and bud and shoot proliferation. New growth became vitrified within 14 days and the cultures reverted to normal after the water was poured away, with the cultures treated for the longer periods (28-56 days) reverting more quickly. Mean bud and shoot production in cultures submerged for 56 days followed by 28 days in air was 15 compared to two in untreated cultures. Retreatment of the apical portions of the vitrified and reverted cultures by 49 days' submergence followed by 28 days' air resulted in a further increase in mean bud and shoot proliferation to 28. The increases in bud and shoot numbers after submergence were due mainly to the initiation and development of adventitious structures on the vitrified and reverted portions of the stems. Rooting in vitro was higher in treated cultures.

Rejuvenation modes of two clones of Sequoia sempervirens (Endl.) obtained from a 50-year-old tree (Clone 1) and a 500-year-old tree (Clone 2) were studied by in vitro culture technique. The progress of the explants towards physiological rejuvenation was assessed by spontaneous rooting, induced rooting, and length of the main shoot. Two criteria (reactivation of isolated apical meristems and ex-flasking stem growth) were used to assess ontogenetical rejuvenation. For Clone 1, frequent subcultures on a medium without hormones effected physiological rejuvenation. Maintenance of explants of both clones on medium with BAP (benzyl-amino-purine) and NAA (naphthalene-acetic-acid) for several months without subculturing was effective to some extent. After frequent subcultures on medium with BAP and NAA the material of Clone 2, was reactivated but later and to a smaller degree than Clone 1 material. The older the original tree, the stronger the treatment needed to obtain physiological rejuvenation. Ontogenetical rejuvenation was more difficult to achieve than physiological rejuvenation.

Larix decidua Mill, was micropropagated in vitro using juvenile tissues from young seedlings as well as tissues from in vitro-cloned propagules. Wounds made to seedling hypocotyls stimulated adventitious bud initiation at wound sites. Initiation frequency was best using 2-week tissue incubation on medium supplemented with 4.4 x 10^-5 molar cytokinin. A cytokinin pulse treatment of nongrowing older adventitious shoots stimulated renewed growth. Clone population sizes were increased in vitro using successive generations of propagules as source tissues for initiation of adventitious buds. Clones were further rapidly augmented by bud break on plantlets horizontally affixed in soil; apices had been excised from these plantlets.

A comparison was made of the growth responses of explants excised from vegetative buds of 15- to 18-year-old Picea glauca(Moench) Voss (white spruce) when cultured upon seven nutrient media. One nutrient medium, GMD, was found to be superior in the induction of shoot primordia (average 8.1 per explant) and in its primary multiplication value (average 3.24 shoot primordia per original bud). Five of the other nutrient formulae also gave rise to shoot primordia, though at significantly lower values. Only explants grown on Schenk and Hildebrandt medium failed to give rise to shoot primordia. Medium GMD was devised after a comparison of elemental concentrations within a range of media that have been published for use with various tree tissue cultures.

he present study describes the histology of adventitious root formation on the in vitro-formed shoots of Picea mariana (Mill.) B.S.P. and P. glauca (Moench) Voss (black and white spruce). Some swelling occurred at the base of the shoot, and some callus was formed below the base under the influence of indole-3-butyric acid (IBA), an active ingredient of the rooting powder used. Some of the cells within the base of the shoot and in the vicinity of the vascular system differentiated into cambium-like cells which later produced tracheid nests and resin canals. The tracheid nests were composed of irregularly arranged tracheids of various sizes surrounded by the cells of the cambium. Some of the derivatives of the cambial cells located at the periphery of the tracheid nests differentiated into the root meristemoids. The cells of these meristemoids were small and contained densely staining cytoplasm and large nuclei. Later in culture, these cells differentiated into the root primordia which then assumed the normal configuration of a root. These roots were connected with the vascular tissue of the shoots through the tracheid nests. The continuity of the vascular system of the tissue culture-derived plantlets of black and white spruce was confirmed by clearing them with sodium hydroxide and then staining.

Differences in bud induction on cotyledons from seedlings of six full-sib families and a wild seedlot of Pseudotsuga menziesii(Mirb.) Franco were observed after culturing on a half-strength Murashige &

mprovement in shoot primordia production was achieved on explants from vegetative buds excised from a 17- to 20-year-old Pseudotsuga menziesii(Mirb.) Franco (Douglas fir) during the dormant season. Seventy-five percent of inoculated explants produced an average of 8.3 shoot primordia each when grown on a modified Boulay medium containing benzyladenine (1 mg/L) and ammonium nitrate (800mg/L). The optimum duration of exposure to ammonium nitrate was 6 weeks. Approximately 66% of these shoot primordia grew to a length of 1.0 to 1.5 cm, and were suitable for subsequent excision. A comparison of shoot primordia initiation amongst nine randomly selected trees showed that distinctly superior and inferior trees occurred, with a range from 100% to 0% of explants showing the shoot primordium response. The average number of shoot primordia per responsive explant showed similar differences with a range from 8.8 to 0. Five out of the nine trees responded favourably with primary multiplication factors from 8.8 to 4.1 primordia per inoculated explant. The origins of shoot primordia and their location on the bud explant were found to be dependent upon the donor tree.

Various juvenile explants from conifers have been, used to form shoot buds in vitro.The best explant must be selected empirically and the number of shoots formed varies with the explant. A comparative morpho-histological examination was made of the sites of shoot initiation arising from embryonic explants of Pinus contortaLoud, and Pinus rigidaMill., cotyledon explants of Pinus radiata.D. Don and P. contorta,and epicotyl explants of Picea glaucaVoss, Picea marianaB.S.P., and Picea engelmanni Parry. The study revealed that despite the different sites and timing of initiation of shoot formation, the patterns of shoot development were similar. In all species the formation of meristematic centres or meristemoids led to bud primordia and finally adventitious shoots with apical domes and needle primordia. This developmental sequence occurred in the absence of concomitant callus formation on the cytokinin-containing medium.

The paper which this Corrigendum refers to is available here: Moisture removal from green sapwood during platen pressing

Four different pretreatments were tested to accelerate drying of Nothofagus fusca(Hook, f.) Oerst. heartwood - prefreezing, compression rolling, steaming at 100 °C, and soaking in hot water. Steaming improved the drying rate, but caused excessive fine internal checking in green wood; its use is restricted to treatment after predrying to about 40% mc. A short period of soaking in hot water at about 70 °C reduced the drying time substantially and was the only treatment suitable for green timber. Neither prefreezing nor compression rolling had any effect on drying rate and both caused excessive degrade.

Compression rolling improved the permeability of Nothofagus fusca (Hook f.) Oerst (red beech) and increased its preservative uptake by up to a factor of six (compared to unrolled controls), without having a substantial effect on the drying rate. Hot-water soaking improved drying, particularly in the radial direction, but had little effect on the permeability. A combination of both treatments conferred no additional benefits over those found for the two individual treatments.

Microscopic observation revealed the probable causes of these results. After compression rolling, the vessel structure (especially tyloses, perforation plates, and vessel to vessel pits) frequently showed deformation, rupture, collapse, and other signs of damage. Thus pathways within the vascular system were reopened for fluid flow. On the other hand, hot-water soaking did not affect the vessel structure substantially, but there was a relocation and partial removal of the extractives encrusting the ray parenchyma cell walls and pit membranes, with a resultant increase in drying rate, which for flat-sawn boards was twice that of unsoaked controls.

Sapwood specimens from Pinus radiata D. Don and Eucalyptus regnans F. Muell. were compressed radially to high strains either between flat platens (unconfined compression) or in a jig which prevented expansion at right angles to the direction of compression (confined compression). Stress at proportional limit, stress at 12.5% strain, and work to proportional limit were analysed. Two types of equation often used to express the relationship between wood strength and specific gravity were inappropriate. The two strength properties and work to proportional limit were greater in confined compression than unconfined compression. In both forms of compression E. regnans specimens had greater strengths than P. radiata specimens.

From density measurements on Pinus radiata D. Don peeler logs, veneer, and plywood, and from bending tests on 5- and 7-ply panels, relationships were derived that predict plywood panel density, bending strength, modulus of elasticity, and compression strength of clear plywood from the basic density of peeler logs. The property-reducing effects of knots were then superimposed on these predictions in an assessment of the log resource that showed current plywood quality may be at least one stress-grade better than the stress values implied by the New Zealand design code. On the other hand, low-density logs yielded plywood with strength properties less than these values. Density of logs and average knot ratios required to achieve desired stress-grades were also identified.

Timber of various stress-grades was passed a number of times through a Computermatic stress-grading machine running at 60 m/min and 150 m/min in a laboratory. The deflection of all the tested points on each stick was recorded, and deflection at each of the points was also determined statically for comparison. The range of dynamic deflection values for each point (termed repeatability) and the mean deflections were also calculated. Data from tests on verification sticks were used to determine differences between deflection measurements taken statically and those taken in a Computermatic machine. There were no consistent differences in mean deflection measurements at the two feed speeds. A mean increase in repeatability error of one-half of one machine measuring unit found at the higher feed speed was considered to be of little practical significance in industry. The modulus of elasticity as determined by the Computermatic machine on the verification sticks at the point of least stiffness was on average slightly lower than the same property determined on the static machine. Three percent of the sticks had modulus of elasticity differences greater than the 10% allowed by the current Australian Standard.

A sample of 78 Pinus radiata D. Don logs was measured and sawn to maximise yields of 100 x 50-mm and 200 x 50-mm timber. The average bending strength and stiffness of the timber were found to depend on the basic density of the log but the lower fifth-percentile strength was more dependent on branch index. For the 28-year-old stand sampled, logs with a low branch index yielded 100 x 50-mm timber of No. 1 Framing grade strength without grading of the timber. When the timber was graded the influence of branch index on strength was reduced but logs with a large branch index yielded graded timber that was below strength.

Height and diameter growth of 5-year-old Pinus radiata D. Don was measured monthly at four forests throughout New Zealand. A conditioned seven degree polynomial was fitted to the cumulative growth. The differential was used to calculate the proportion of growth in each month. There were significant differences in growth pattern between the four forests.<

An area of Pinus radiata D. Don with extreme magnesium deficiency in southern Kaingaroa State Forest was treated with a mixture of ground dolomite (CaCO₃.MgCO₃) and Epsom salts to supply 100 kg Mg/ha. Recovery in tree appearance and growth was slow but by 2 years after treatment a strong response was noticeable. Over a 5-year period trees treated with dolomite (750 kg/ha) and Epsom salts (200 kg/ha) grew 66% more in height and 45% more in diameter than untreated trees.

Biomass determinations 5 years after fertiliser application showed that treated trees had taken up 29 kg Mg/ha more than untreated trees. Although magnesium was probably the major growth-limiting nutrient at this site, the particular amendments used to remedy the deficiency included other nutrients (calcium and sulphur) that may have been in short supply. The dolomite component may also have affected soil dynamics by its liming action. Slight boron deficiency was induced in the magnesium-treated pines.

The performance of 56 Eucalyptus species (119 provenances) at two exposed, seasonally dry, hill country sites in the Wairarapa district was assessed at age 5 years. There were significant differences among species in height and diameter growth, Eucalyptus tortoise beetle (Paropsis charybdis Stal) and leaf roller caterpillar (Strepsicrates macropetana Meyrick) damage, wind damage, stem straightness, crown width, crown density, and branch size. Eucalyptus cordata Labill., E. fastigata Deane et Maid., E. fraxinoides Deane et Maid., E. oblique L'Herit, E. pulchella Desf., and E. regnans F. Muell. ranked highly for most traits at both sites and are considered to be the most suitable of those species tested.

Growth of naturally regenerated Beilschmiedia tawa (A. Cunn.) Kirk (tawa), Dacrydium cupressinum Lamb, (rimu), and Prumnopitys ferruginea (D. Don) de Laub. (miro) over 22 years in untagged and selectively logged podocarp/tawa forest at Pureora, central North Island, New Zealand, was studied in relation to crown class, position in relation to canopy gaps, competition, and phase of forest growth cycle.

Height increment of seedlings (defined as <2.5cm dbh) and diameter increment of saplings and poles (5-30 cm dbh) were significantly affected by crown class in all species. Growth rates were similar in all species; height growth averaged 12-13 cm/annum in dominant and co-dominant plants and 3-6 cm/annum in dominated plants, while diameter growth averaged 2-3.5 mm/annum in dominant and co-dominant plants and 1-2 mm/annum in dominated plants. Tawa saplings and poles grew significantly faster in logged forest (c. 2.5 mm/annum) than in untagged forest (c. 1.5 mm/annum), a reflection of the increased light levels resulting from canopy disruption.

Mortality rates of dominated seedlings (c. 1%/annum over 22 years) were similar in tawa, rimu, and miro. These species maintain slowly-turning-over banks of slow-growing established seedlings in the understorey, surviving on average for c. 100 years at Pureora, and capable of responding to opening or thinning of the canopy. Although tawa can develop to maturity in the understorey, miro and especially rimu appear to become increasingly light-demanding after the seedling stage at Pureora, and to be significantly gap-dependent for development to maturity.

Lignin concentration in the tracheid cell wall of Pinus radiata D. Don was examined in relation to growth rate, stem eccentricity, site, and silvicultural treatment, using interference microscopy. The greatest variation occurred in the cell corner middle lamella, with a range of values from 76% to 92% v/v. S2 lignin concentration varied from 20% to 22% v/v. The observed variation appears to be independent of any of the factors examined.

The influence of initial degree of pore saturation (in the range of 60-100%) and amount of compression (5-35% strain) on moisture expression and energy relationships during platen pressing of small rectangular blocks of sapwood from Pinus radiata D. Don and Eucalyptus regnans F. Muell. was investigated. The dependent variables were related to initial degree of pore saturation or initial moisture content and percentage strain by means of regression equations. Reductions in percentage moiture content ranged from 2% to 57% in P. radiata and from 0% to 62% in E. regnans. Energy ratios were greater in P. radiata (145-913) than E. regnans (46-622) and indicate the potential of compression drying in fuelwood production, especially for the pine.

A Corrigendum to this paper is available here: Corrigendum for Wingate-Hill, R. & Cunningham, R. B. 1986: Moisture removal from green sapwood during platen pressing

A conversion study carried out at a veneer slicing plant involved the slicing of 23 bolts of pruned Pinus radiata D. Don. The slicing operation produced several categories of three grades of clear veneer and one grade of knotty veneer. Three slicing strategies were used. Over-all veneer conversion peaked in the middle size range and fell rapidly as small-end diameters dropped below 425 mm.

Higher relative spray deposits were found on pinnae of bracken fern (Pteridium esculentum Forst. f.) Ckn.) when herbicides were applied from a helicopter in a lower rather than higher volumes of water. At the same application volumes a formulation containing less surfactant gave higher relative deposits than surfactant-rich ones. The differences can be explained by assuming that droplets bounce when they fall on a wet surface. This hypothesis has been supported in laboratory experiments.

A 5-year-old plantation of Eucalyptus nitens Maid. grew over 4 m in height and added basal area of 4.6 m²/ha in 12 months. Production of dry matter in the above-ground portion of the stand averaged 36 tonnes/ha/annum over a 2-year period with over 70% in bole material. The season of sampling was unimportant in determining the biomass of stand components since foliage production was closely linked with leaf litterfall. Branch and stem mass increased with time as woody litterfall was small compared with production. Nutrient concentrations in living tissue tended to decrease with increased tree size and often varied among seasons. Although season of sampling affected estimates of stand nutrient content, no simple pattern of change was observed. Calorific values of foliage and live branches were highest in summer or autumn but seasonal differences in stem components were not statistically significant.<

The weight of the forest floor under Pinus radiata D. Don averaged about double that under Eucalyptus regnans F. Muell. up to age 17 years. The concentrations of nitrogen, phosphorus, and potassium were higher and of calcium lower in the forest floor under pine. Differences in mineral soil nutrient status had apparently developed by age 4 years with more total nitrogen and exchangeable calcium but less exchangeable magnesium in the top 40 cm of soil under E. regnans than under P. radiata.

An 18-year-old Pseudtsuga menziesii (Mirb.) Franco (Douglas fir) plantation growing on a hygrous high-country yellow-brown earth soil in Canterbury, New Zealand, showed localised symptoms of ill health - absence of cones, stunting and chlorosis of needles, premature needle cast and a premature decline in shoot growth and basal area increment. Soil and foliar nutrient analyses indicated phosphorus deficiency was the principal cause of the growth disorder, and this was confirmed by growth responses to applied phosphorus in field and greenhouse trials. Soil exchangeable aluminium levels were high and aluminium toxicity may have compounded phosphorus deficiency problems. In the field trial, superphosphate increased needle nitrogen content, but no response was obtained to nitrogen applied as urea either alone or in combination with other nutrients. Urea significantly reduced phosphorus uptake at the end of the first growing season, but not the second. In contrast to the field trial, Douglas fir seedlings in the greenhouse trial responded to nitrogen applied as ammonium nitrate provided phosphorus was also applied. It is suggested that immobilisation of urea-nitrogen in soil organic matter may have contributed to the failure of trees in the field trial to respond to nitrogen.

The change in tree form of Pinus radiata D. Don after application of nitrogen and/or phosphorus fertiliser was examined through analysis of bark thickness, relative taper curves and tree volume equations. Based on some 1300 sectionally measured trees, the results indicate that application of phosphorus leads to thinner bark and a slight improvement in form, while nitrogen alone results in a slight deterioration in form. A weak negative relationship between the change in form and the basal area response to fertiliser suggests that only when basal area response exceeds 35% will average form improve by more than 2.5%.

The increase in basal area growth 4 years after fertiliser application in 44 trial comparisons in which 200 kg/ha nitrogen had been applied to Pinus radiata D. Don was regressed against soil and environmental variables and silvicultural treatments. Large positive responses tended to occur in stands less than 10 years old, particularly if growing on nitrogen-poor soils and if they had recently been pruned or thinned. Smaller positive responses occurred in older stands, and in stands on soils with total-nitrogen greater than 0.2%. Negative responses could occur if nitrogen was applied to stands on soils with Bray phosphorus less than 10 ppm.

The period of enhanced growth due to fertiliser was previously considered to last for 4 years but it now appears that it may be followed by a period during which the treated trees grow slightly more slowly than the untreated. This affects economic evaluation of the response. The normal conclusion that fertiliser is best applied close to rotation age, is somewhat modified by the fact that response decreases with age of stand. Timing therefore appears to be a matter of economic indifference.

The growth response of Pinus radiata D. Don seedlings was measured for 3 years after the clearfelling and harvesting of a Nothofagus spp. forest using the following treatments: podocarp logging only; podocarp logging and burning; logging of all tree species to chipwood standard (10 cm dbh); chipwood logging and burning; with or without fertiliser and/or herbicide treatments. Seedling mortality 3 years after planting exceeded 55% in the unburnt treatments but was less than 39% in the burned treatments. Height and diameter growth were better in the burned than the unburned treatments, and in the chipwood than the podocarp logged plots. Fertiliser application produced no measurable effect on seedling growth rates but herbicide application induced a small growth increase. Nutrient levels in the soil and foliage were adequate for the needs of P. radiata. Few of the interactions between burning, logging method, fertiliser, and herbicide application were significant.

Studies of Pinus radiata D. Don root systems in southern Kaingaroa State Forest showed clearly that the trees were making full use of the extra soil volume provided by ripping on both Kaingaroa gravelly sand and Kaingaroa loamy sand. These studies also demonstrated that root growth ceases when the soil resistance to penetration exceeds 3 MPa. The extra soil volume provided led to extra tree growth on Kainaroa gravelly sand, but not on Kaingaroa loamy sand. Ripping also lessened the incidence of severe juvenile instability on Kaingaroa gravelly sand.