In New Zealand, grading machines are programmed to produce grades of Pinus radiata D. Don (radiata pine) with properties equivalent to existing visual grades. However, because (a) mechanically sorted timber can contain larger defects than visually sorted timber of similar strength, and (b) the increase in strength on drying is less in timber containing larger defects than in timber containing smaller defects, it has been necessary to impose visual grading requirements on radiata pine that is mechanically graded while green.

A study of the in-grade properties of radiata pine showed that combined visual and mechanical grading gives a better prediction of strength than either method alone, but the prediction of stiffness is not significantly improved by visual in addition to mechanical grading.

Extended oxygen delignification of three types of alkaline pulps from Pinus radiata D.Don was investigated. Kraft, kraft-anthraquinone (kraft-AQ), and soda-anthraquinone (soda-AQ) pulps at 40 and 60 Kappa number were treated with oxygen to remove about 60, 70, and 75% of their residual lignin. Extended oxygen treatments resulted in less selective delignification, higher brightness at a given Kappa number, and generally less strength degradation in 60 Kappa than in 40 Kappa pulps; and in less selective delignification, lower brightness at a given Kappa number, and lower strength in soda-AQ pulps than in kraft and kraft-AQ pulps. The yields of kraft-AQ and soda-AQ pulps remained higher than those of kraft pulps after extended oxygen delignification. At 25 Kappa number use of extended oxygen treatments increased total yields by 3% over those attainable through continued pulping. With careful control, oxygen delignification of alkaline pulps could be extended to at least 60% lignin removal before significant strength losses occurred.

Simulated sampling of nine forest plots was used to compare estimated plot component weights with known weights based on complete harvest. On average, estimates based on the relationship plot weight = (Σ sample tree weight)/ (Σ sample tree basal area) x (plot basal area) showed a negligible negative bias and were approximately as variable as those found using logarithmic estimating equations. The minimum estimates using the basal area ratio method were slightly poorer, but the means and maxima consistently better than those found using logarithmic regressions. Stratified random sampling using five diameter strata was only slightly better than random sampling.

Rhodamine B dye, Lissamine green dye, and demethylchlorotetracycline were evaluated as tracers for monitoring bait acceptance by brush-tailed possum (Trichosurus vulpecula Kerr) populations. Demethylchlorotetracycline left no detectable trace in possums, even at high dosages. Lissamine green was not persistent enough externally and did not stain the gut tissue. Rhodamine B marked animals for 7 days when used at 0.5% concentration, surface-coated on baits, and can be used at up to 1% concentration without reducing the palatability of the bait. Rhodamine B was therefore selected as a suitable tracer.

Colonisation of pruning wounds made by the removal of small (<25mm) and large (>25mm) branches leaving three different stub lengths (0, 15, and 30 cm), in spring, summer, autumn, and winter, was studied in a 4-year-old stand of Eucalyptus delegatensis R.T. Baker in Kaingaroa State Forest. Isolations were made from all pruned branch stubs. Of the 288 trees examined, 46% had visible rot and a further 29% showed discoloration of the sapwood indicating an early stage of decay. In most of these trees, the rot-inducing fungi had gained entry through branches which had died through suppression. Of the experimentally pruned branches, the largest proportion with rot were those flush-pruned in spring and summer (eight and five respectively out of 24); only one of the autumn flush-pruned and none of the winter flush-pruned branches had rot. At the end of 12 months, 27.4% of the isolates from experimentally pruned branch stubs were of fungi capable of causing decay. The most common rot fungus isolated was Stereum purpureum (Pers, ex Fr.) Fr., which formed 12.4% of the total number of isolates. The incidence of decay fungi isolated from pruning wounds declined with season, in the order spring, summer, autumn, winter. The influence of stub length and branch diameter on the incidence of decay fungi varied from species to species. Infection of pruning wounds by decay fungi cannot be entirely avoided by silvicultural means but its incidence can be reduced by pruning in winter.

Seasonal frost-tolerance of Eucalyptus saligna Sm., Eucalyptus regnans F. Muell., and Eucalyptus fastigata Deane et Maiden was determined by frosting seedlings monthly during 1976 in a controlled environment. Frost tolerance of E. saligna ranged from c. -3°C in summer to -7°C in winter, of E. regnans from c. -3.5°C in summer to -9°C in winter, and of E. fastigata from c. -4°C in summer to -10°C in winter. Seedlings started hardening in April; E. saligna reached maximum tolerance in late June, whereas E. fastigata reached maximum frost-tolerance in late July, the coldest part of winter. The seed source for E. regnans was changed in July, and so it is unknown if it continued hardening during July. Eucalyptus saligna started to deharden during July, whereas E. fastigata started to deharden a month later, and all three species continued to deharden throughout October. Some variation in the absolute frost-tolerances can be expected depending on the growing climate (nursery location and seasonal variation).

The frost tolerance of the three eucalypt species is less than that of Pinus radiata D. Don for all times of the year, and so their establishment should be restricted to sites with good air drainage to minimise the risk of frost damage.

During 1980, increment core samples were collected from Pinus caribaea var. hondurensis Barr. & Golf. (Caribbean pine) on 38 sites throughout the afforested areas of the two main islands of Fiji. In addition, 110 trees were felled and sectioned to give information on the relationship between increment core wood density and density of the merchantable stem to 100 mm diameter. Good correlations between increment core and whole-tree values were established.

Consistent patterns of wood density increase with tree age and decrease with height in the stem were recorded. Together, tree age and site altitude were shown to account for 85% of the variation observed in plantations ranging in age from 8 to 25 years.

On a 15-year rotation, high altitude (>300m) and low altitude (<300m) sites can produce timber with average basic densities of 515 and 465 kg/m³. Equivalent values for a 25-year rotation would be 540 and 475 kg/m³ respectively.

Variation in the density of the wood of Pinus radiata D. Don was studied in a progeny trial comprising 26 open-pollinated families arranged in nine randomised blocks. Samples of wood taken from different radii at breast height on 692 trees were divided into inner, middle, and outer segments, each containing five annual rings. The density of each segment and a mean for all 15 rings were determined for each tree.

Analyses of variance showed highly significant differences between families and between blocks. Point estimates for heritability ranged from 0.51 to 0.72.

On the basis of common knowledge, it may be assumed that on average each radial sample within a stem showed a consistent trend of density increasing with age, as xylem was deposited further and further from the pith. If, then, the variance of density is regarded as that of a point anywhere within the breastheight cross-sections of some 600 trees, a large part of the statistical effect of this trend may be extracted from the data as a linear regression component. With that concept, the linear regression component in this experiment accounted for 65% of the total variance in wood density. The mean density/age gradient was 7.87 kg/m³/yr, with a standard deviation of 3.51 kg/m³/yr. There were highly significant differences between the families in the gradient: its heritability was estimated as 0.27.

Density showed the usual weak, negative phenotypic correlation with radial growth-rate. A multiple regression analysis, relating density to the radius and height of the stem jointly, accounted for 2.2% of the total variation (p < 0.001), the partial regression coefficients being negative for radius and positive for height. In a similar analysis of the pooled within-families variance the regression coefficients were again negative for radius and positive for height, and the joint regression accounted for 16% of the total variation (p < 0.001).

Genetic, environmental, and phenotypic correlation coefficients were estimated for 10 characters. There appeared to be little or no association between density and external characters affecting log quality, but the different determinations of density showed consistently strong positive genetic correlation amongst themselves. This suggests that in each tree the same genes were acting on wood density, and acting in the same way, at all stages during the 15-year period.

Various infection levels of Dothistroma pini Hulbary were induced by artificial inoculation of Pinus radiata D. Don trees 1 year after establishment in 1972 in a plantation in Kaingaroa State Forest, and disease levels were recorded quarterly for 8 years. Tree growth between the second and eighth years of the study was examined by stem analysis of a sample of 120 trees from the second thinning and by sectional measurement of the remaining final-crop trees for volume.

Inoculated plots exhibited higher disease levels from 1973 to 1976 and lower annual volume increments from 1975 to 1979 than plots which were sprayed with fungicide. Disease/volume-loss relationships were analysed by multiple regression, and it was shown that volume growth was reduced in proportion to increase in disease level.

Dry matter production was estimated in a plantation of Pinus radiata D. Don with rows increasing in age from 5 to 10 years and planted at a spacing of 1 x 1.5 m.

The weights of current (7.8 t/ha) and total foliage (13 t/ha) remained reasonably constant with stand age. Total branch mass increased from 11 t/ha at age 5 to 36 t/ha at age 10, and stem material from 52 to 154 t/ha over the same period. Mean annual increment increased with age and was predicted to reach a maximum of 21 t/ha at age 10 for the total above-ground biomass. Similar analyses for stem and for stem-plus-branches indicated a peak mean annual increment at age 10 of 16 and 20 t/ha, respectively.

In 1980 fertilisers were applied to more than 30 000 ha of exotic forest plantations. This area, about double that treated in 1975, was made up of 7600 ha of new plantings, 19 000 ha of established forest, 3900 ha of marram-grass (Ammophila arenaria (L.) Link) sand stablisation, and less than 1000 ha of nurseries, seed orchards, amenity areas, etc. During the year 14.5% of all new plantings received fertiliser, and 2.2% of established forests.

Between 1975 and 1980 the use of nitrogen fertilisers trebled to 1900 tonnes N/year, the use of phosphatic fertilisers doubled to 1100 tonnes P/year, but there were no increases in the use of potassium and magnesium and use of boron declined, Small amounts of molybdenum were used for the first time.

The major change in the types of fertilisers used was an increased use of high-analysis nitrogen-phosphorus fertilisers, particularly diammonium phosphate. The year 1980 saw a major advance in the quality of aerial application of fertilisers, large areas being treated by a helicopter fitted with a guidance system.

It seems unlikely that fertiliser use by 1985 will reach the levels predicted previously.

Sporocarps of Hymenogaster albus (Klotzsch.) Berk, et Br. were found to be associated with roots of several species of Eucalyptus. The fungus was isolated from the mycorrhizal roots of E. delegatensis R.T. Bak., E. nitens Maiden, and E. sieberi L. Johnson. Seedlings of E. saligna Sm. inoculated with spore suspensions of H. albus formed pale-brown to golden simple pyramidal mycorrhizas.

Analyses are given of dry matter components of root systems of 97 Pinus radiata D. Don trees, 3 to 8 years old

After felling of the first crop of Pinus radiata D. Don on rhyolitic pumice soil, an area was cleared of all logging debris. During the ensuing 16 years of the second P. radiata crop all litter material, including that of a precommercial thinning, was raked off this area regularly. Just prior to a late second-thinning at age 16 (from c. 1000 to 250 stems/ha) the impact of this treatment on stand productivity, foliar nutrient, and soil properties was examined.

It was estimated, using stem analysis procedures, that the raked area contained 471 m³ total stem wood/ha compared to 535 m³/ha in a control area - a reduction in productivity of some 12%. This was considered a real difference as basal areas were identical in the two areas at age 6 years.

Analysis of the current year's foliage prior to thinning showed that the only nutrient significantly lower in the raked area was boron - 7.2 ppm compared to 10.6 ppm for the control area. In addition to boron, potassium and manganese were also significantly lower in older foliage, but neither approached levels considered critical for growth. A year after thinning, differences in boron concentrations increased and foliage nitrogen concentrations in the raked area became critical for growth and significantly lower than those in the control area.

The biggest difference in soil properties between the two areas occurred at a depth of 5-10 cm, rather than in the surface 5 cm. Consistent with the removal of organic matter, the raked area had lower concentrations of carbon, total nitrogen, total phosphorus, Bray 2 phosphorus, and moisture. The cation exchange capacity and levels of exchangeable calcium, magnesium, and potassium were also significantly lower in the raked area. The depletion effect was greatest on exchangeable magnesium levels which were not so well buffered as calcium and potassium in this rhyolitic pumice soil. The relatively high reserves of phosphorus and nitrogen in this soil were not seriously depleted by the treatment.

Accumulation of organic matter and nutrients in the forest floor was examined in a heavily stocked 16-year-old stand of second-rotation Pinus radiata D. Don growing on a yellow-brown pumice soil. The forest floor contained 55 464 kg drv matter/ha and 552 kg N/ha, 36 kg P/ha, 32 kg K/ha, 172 kg Ca/ha, 34 kg Mg/ha, 0.3 kg B/ha, 2.5 kg Zn/ha, 2.5 kg Cu/ha, and 24.1 kg Mn/ha. The relative rate of movement of nutrients through the forest floor was K > > B > Mn > (P, Mg, Ca) > (Zn, Cu) > (N. organic matter).

Tension plate lysimeters were used in Kaingaroa State Forest to determine the impact of harvesting of Pinus radiata D. Don (radiata pine), followed by slash-burning, on nutrient losses by leaching. Soil water was monitored just beneath the mineral soil surface, and at 20-, 45-, and 100-cm soil depths. Both operations increased the leaching of nutrients to lower soil depths; however, the effect was small and short-lived. Nitrogen in the nitrate form exhibited the greatest response as elevated concentrations in soil water persisted to 3 years after logging. The maximum monthly mean nitrate level recorded at a soil depth of 100 cm was 1.3 mg N0₃-N/L in the logged area and 2.1 mg/L in the burned area, compared to 0.12 mg/L in the control. Logging and slash-burning in radiata pine forests on the central volcanic plateau have only a small effect on nutrient leaching losses and do not appear to threaten soil fertility.

Past failure of yellow tree lupin (Lupinus arboreus Sims) at Pouto Forest can be ascribed to a combination of factors including multiple nutrient deficiencies, exposure, and pest attack. Marked growth responses to molybdenum application and to sulphur in the presence of molybdenum have been obtained. A small response to boron in the presence of molybdenum was also noted.

Deficiencies of molybdenum, sulphur, and boron have not been reported in other New Zealand sand dune forests. At Pouto it is likely that the combination of neutral sand pH, high leaching potential, and absence of fresh sand accretion from the foreshore results in losses of these elements which exceed the natural input.

Correction of nutrient deficiency is expected to increase plant vigour to a point where other factors have a negligible effect on the development of an adequate lupin cover. Radiata pine (Pinus radiata D. Don) trees are unlikely to be affected by molybdenum deficiency but their sulphur and boron status should be monitored during growth.

Seedlings of Pinus radiata D. Don (radiata pine) raised in seven nurseries in New Zealand were subjected to advective frosts in controlled-environment rooms in autumn (May), winter (August), and spring (October) to determine their seasonal patterns of frost tolerance. At each of these times four levels of frost were provided which allowed differences in frost tolerance to be quantified. The seedlings from Kaingaroa and Athol nurseries withstood frosts of -11°, -12°, and -10 °C in May, August, and October respectively, whereas Bulls stock tolerated -6°, -9°, and -5.5 °C at these times. Stock from Edendale, Rangiora, Te Teko, and Owhata were intermediate in their responses. Although there was general agreement with published work that changes in temperature and daylength appeared to relate to frost tolerance, a more precise relationship could not be found. In fact, generally, the higher the altitude of the nursery the greater was the frost tolerance of the stock produced.

Seasonal frost-tolerance of Pinus radiata D. Don (radiata pine) was determined at 4-weekly intervals by simulating white frosts in a controlled environment room. Summer and winter frost-tolerance levels were c. -6°C and -12° C respectively. Two consecutive frosts, 24 hours apart, increased the damage although this was not usually significant. Individual seedlings exhibited a range of tolerance suggesting that genetic screening for frost tolerance may be feasible. The frost tolerance of Pinus muricata D. Don (muricata pine) ranged from -5.5°C in the summer to -12.5 °C in the winter, and that of Pseudotsuga menziesii (Mirb.) Franco (Douglas fir) from less than -4°C in the summer to more than -12.5 °C in the winter.

Wood samples were obtained from three plots subjected to different treatments (N₀P₀, N₁P₁ and N₃P₁

A recent example of wind damage in a Pinus radiata D. Don stand on the Canterbury Plains clearly demonstrated that:

(1) Wind-damage was greater in the immediate lee of two exposed stand edges. One edge was caused by adjacent open ground and the other by a taller stand to windward.

(2) There were turbulent eddies and high-force backdrafts in the lee of a tall relatively non-porous stand.

Corrigendum for Pekelharing, C.J. 1979: Fluctuation in opossum populations along the north bank of the Taramakau Catchment and its effect on the forest canopy. 9(2), 212-224.

The paper which this Corrigendum refers to is available here: Corrigendum for Pekelharing, C.J. 1979: Fluctuation in opossum populations along the north bank of the Taramakau Catchment and its effect on the forest canopy

New Zealand isolates of Armillaria novae-zelandiae and A. limonea were compared to determine if they could be distinguished in pure culture. Several consistent differences in cultural characters between isolates of A. novaezelandiae and A. limonea could be used reliably (correct answers were obtained in > 90% of the comparisons) to distinguish between the 2 species and so provide a method to identify isolates obtained from diseased tissue. In pure culture, sporophores of A. novae-zelandiae were produced, but not those of A. limonea. Death of P. radiata seedlings inoculated with A. novae-zelandiae (23%) was higher than for those inoculated with A. limonea (18%), but the difference was not statistically significant. However, there were highly significant differences in virulence between individual isolates within each species.

Internal checking has limited the use of high temperature drying for radiata pine sawn timber in New Zealand. Research at the Forest Research Institute has shown that internal checking occurs mainly after drying is completed and can be prevented in some sizes, including 100 x 50 mm, by following a precise drying regime including adequate final reconditioning.

Annual dry matter increment of E. nitens and E. fastigata in Rotoehu State Forest was 20 and 15 tonnes/ha respectively. This is of the same order as the maximum value of 17 tonnes/ha at age 17 years published for an age series of Pinus radiata. In the Eucalyptus species, compared with pine, the nutrient content per unit of energy harvestable varied from the same order of magnitude for phosphorus, to almost 4 times as high for nitrogen. Fast growing Eucalyptus species warrant further study as potential sources of energy from biomass in New Zealand.

Diameter increments, heights, and bark thicknesses are compared for trees of Eucalyptus regnans, E. obliqua, intermediates between these two species, and E. globulus occurring naturally in 13 mixed-species stands of even-aged tall-open forest aged 20-79 years in south-eastern Tasmania. E. regnans, E. obliqua, and intermediates did not differ consistently or substantially in growth rates in any of these parameters except that E. obliqua generally had thicker bark than E. regnans. E. globulus had higher diameter increments than the other species at about 20 years of age but lower increments after about 40 years of age. Height or bark thickness of E. globulus did not differ consistently from the other species at any age except that its bark was thinner than that of E. obliqua. It is concluded that E. globulus might be favoured for short rotations because of its higher diameter increments at younger ages and the other species might be favoured for longer rotations. There seemed to be no silvicultural reason to favour any one of E. regnans, E. obliqua, or intermediates over the others when these species are growing naturally in mixture.

Seedlings of Pinus radiata D. Don. were subjected to a series of different diurnal frost temperature programmes in a low temperature controlled environment room. Four rate of freeze, 4 rate of thaw, and 4 low temperature duration treatments were examined over 3 seasons and at 2 minimum temperatures. Increasing the rate of freezing from 2.3° to 10°C/h and increasing the freeze duration from 2 to 8 h both resulted in increased seedling damage. The response to the rate of thaw treatments was consistent with the duration response probably because plants were frozen longer when slow (2.5°C/h) rather than fast (10°C/h) thaw rates were used. Frost damage caused during thawing in darkness was closely similar to that caused when thawing occurred under light conditions potentially capable of sustaining photosynthesis. Within all treatments, decreasing the minimum temperature used from -8° to -10°C resulted in increased damage but did not alter the overall responses obtained. The responses were also similar over 3 different seasons when plants were at different levels of cold hardiness development.

The development pattern of mortality due to Armillaria root rot in first rotation young Pinus radiata D. Don, planted on sites cleared of indigenous forest, was analysed statistically. Rates of progress of mortality differed between study sites, but there were no significant relationships between mortality rate and various stump characteristics such as species and stump density. The pattern of mortality increase over 3 years did not support the concept of radially expanding infection centres, but instead resulted largely in consolidation of existing disease patches and the appearance of new disease centres. It is therefore postulated that initial development of mortality does not occur from contact between pines but rather occurs at random within disease patches, which are delineated by the old growth stumps and residual root systems colonised by Armillaria root rot.

A computer program to simulate forest plantation management in an interactive manner is described. It has been inmplemented in BASIC for ICL 2980, Radio Shack TRS-80, and Tektronix 4051 computers.