Showing papers on "Pinus radiata published in 1997"

How pine cones open

Abstract: The scales of seed-bearing pine cones move in response to changes in relative humidity. The scales gape open when it is dry, releasing the cone's seeds1. When it is damp, the scales close up. The cells in a mature cone are dead, so the mechanism is passive: the structure of the scale and the walls of the cells composing the scale respond to changing relative humidity. Dissection of cones from the Monterey pine, Pinus radiata, revealed to us two types of scale growing from the main body of the cone — the ovuliferous scale and the bract scale. The larger ovuliferous scales respond to changes in relative humidity when removed from the body of the cone.

Comparison of some soil properties under Pinus radiata and improved pasture

Abstract: Some properties of surface mineral soils under Pinus radiata were compared with those under adjacent pasture at ten farm‐forestry sites in the Manawatu, New Zealand. None of the sites had received lime in the last 10 years. Generally, the soil samples under P. radiata had lower pH and higher extractable aluminium concentrations than their counterparts under pasture. Exchangeable calcium values were lower under P. radiata, by 96–1275 kg/ha. Tree uptake and forest floor development can account for up to 550 kg/ha; at six sites the difference was less than 550 kg/ha, suggesting that calcium generally was conserved by the P. radiata ecosystem. Soil exchangeable sodium and magnesium values were usually greater under P. radiata than under pasture; this probably resulted from the interception of airborne sea‐salt by the P. radiata canopy and subsequent transfer to the soil. There were no general trends in the data for available phosphorus and exchangeable potassium. Total nitrogen was often lower in the...

Tree roots and slope stability : a comparison between pinus radiata and kanuka

Abstract: Increasingly, in the East Coast region of the North Island of New Zealand stands of indigenous regenerating kanuka (Kunzea ericoides var. ericoides (A.Rich.) J.Thompson) are being felled and replanted with Pinus radiata D.Don. Conversion has occurred predominantly on erosion-prone hillslopes where storm-generated landsliding has been widespread and severe, but data on the relative effectiveness of these two forest species in enhancing slope stability are rare. For kanuka andP. radiata, shear stress-displacement curves for their corresponding potential shear planes were measured at two sites by in situ direct shear tests on soil with and without roots. The contribution of roots to soil strength was first estimated by calculating the difference between the maximum shear stress of the shear stress-displacement curves obtained for soil with and without roots. Results suggested that for individual trees the contribution from the roots to soil strength on a root cross-sectional area per unit shear area basis was independent of species for the two tree species tested. There were, however, significant differences in stand density between these two species. These results were then used to obtain relationships between shear stress and shear displacement at the peak of the shear stress-displacement curve, and between cross-sectional area of roots per unit shear area. Taking the shear strength of the combined soil-root system as the peak value of the shear stress-displacement curve produced from the in situ direct shear tests, a limit equilibrium slope stability analysis method was used to derive the safety factors. A simple model developed using the relationship between the shear strength of the soil-root system, the specific root crosssection area, and slope angle was then used to determine safety factors for typical stand densities of naturally regenerating kanuka for comparison with different P. radiata management regimes at equivalent stages of growth. The model predicted that safety factors for stands of P. radiata in the first 8 years after establishment would be lower than for equivalent-aged stands of fully-stocked regenerating kanuka under similar conditions. However, after 16 years the safety factor for a stand of kanuka would be lower than that for P. radiata at final stocking densities typical of framing and biomass regimes. In areas where vegetation plays a major role in soil conservation and erosion control, the model can be used to compare the stability of forested slopes with different species New Zealand Journal of Forestry Science 27(2): 216-233 (1997) Ekanayake et al.—Pinus radiata and kanuka roots and slope stability 217 and stand densities. However, the model does not take into account the effect of buttressing by mature tree roots.

Tree biomass equations for short rotation eucalypts grown in New Zealand

Abstract: Five species of eucalypts, namely Eucalyptus ovata, E. Saligna, E. globulus, E. nitens and E. regnans were planted, sampled and harvested to develop regression equations to be used for non-destructive estimations of total tree dry weight when grown under a short rotation regime. A total of 458 trees were sampled between 2 and 5 years old. Their diameters ranged between 10 and 314 mm, heights 1.6–18.1 mm and weights 0.4–199 kg. A number of equations were developed from these parameters and tested statistically. The best-fit equation for a group of Eucalyptus species incorporated the product of the square of the diameter (D2) and height (H): tree dry weight (W) = 1.22D 2∗ H × 10 −4 . This equation predicted the above ground tree dry weight to within 20% accuracy. The equation developed for eucalypts would be suitable if directly applied to other tree crops such as Pinus radiata or Acacia dealbata under SRF management regimes.

The effect of evergreen and deciduous coniferous plantations on the field layer and seed bank of native woodlands

Abstract: Vegetation and seed bank changes due to the replacement of a native woodland 29 yr ago by coniferous plantations (evergreen coniferous Pinus radiata and deciduous coniferous Larix kaempferi) were studied in a replicated experiment in the Basque Country, northern Spain. In the vegetation the species richness was lower in both coniferous plantations than in the native woodland but there was no significant difference in species richness between the two coniferous plantations. The highest similarity between the vegetation and the seed bank was in the P. radiata plantations (0.51). There was higher vegetation similarity between the native woodland and the larch plantation (0.65) than that with the pine plantation (0.58). Seed bank species richness was higher in the larch plantation than in the native woodland but species richness in the seed bank did not differ between the coniferous plantations. The seed bank showed no difference in the species similarity between the plantations and the native woodland. This was mainly due to the similarity between the broad ranged species. In the coniferous plantations the vegetation diversity was lower than in the native woodland; however, in the seed bank the diversity was higher. Coniferous plantations affected mainly the shade-tolerant and shade-intolerant vernals (Caltha palustris, Galium odoratum, Heleborus viridis and Saxifraga hirsuta), which disappeared from the field layer of plantations while the shade-intolerant not vernals were favoured by the plantations (Blackstonia perfoliata, Danthonia decumbens, Deschampsia flexuosa, Hypericum androsaemum, Holcus lanatus, Lotus corniculatus and Plantago lanceolata). There was no significant difference in vegetation or seed bank between the two types of coniferous plantations.

Native provenances of Pinus radiata in New Zealand: performance and potential.

Abstract: Provenance testing of Pinus radiata in New Zealand has run in parallel with an intensive breeding programme that exploited local 'land-race' stocks. The species was long known to occur at three places on the Californian mainland coast, AAo Nuevo (Lat. 37"N), Monterey (36.5') and Cambria (35S4), but has since proved to include the pines of Guadalupe Island (297 and Cedros Island (28') off the Baja California Peninsula. Very limited provenance testing began in the 1950s, with comprehensive testing on a few sites in the mid-1960s, followed in 1980 by a countrywide series on 23 sites involving just the Californian mainland provenances. Different profiles of site adaptation among provenances have emerged. AAo Nuevo and Monterey are the best adapted overall to New Zealand conditions, but Aiio Nuevo is much less adapted to P-deficient clays, yet better adapted to cold, snow-hazard sites. Cambria is susceptible to needle-casts, shoot dieback, and frost and snow damage, but has toleratedpoor soils. Guadalupe, while showing some adaptational problems and slower growth as a pure strain, has very straight stems and 10% higher corewood density, and has given very promising hybrids with local stock. Cedros, as a pure strain, is much slower growing with severe adaptational problems, although hybrids have grown well. Local stocks are evidently 'mixtures' that have originated mainly from AAo Nuevo (50-75%), the balance from Monterey. To start the breeding with local stocks proved right, but native-provenance material still promises to make valuable contributions. In particular, Monterey material may boost edaphic tolerances, and Guadalupe hybrids may have a significant place. Introduction Pinus radiata breeding in New Zealand began on the twopronged assumption that provenance variation would be unimportant and that local 'land-race' stocks would suffice as a genetic base, although a very limited provenance trial was planted on two sites in 1955 (Shelbourne et al., 1979). Early provenance trial results in Australia (Fielding, 1961), while showing some provenance variation, endorsed the use of local stocks. Bannister (1959), however, stressed that the species was actually more widely distributed than previously thought, since it included the pines of Guadalupe Island and possibly those of Cedros Island as well. Thus it comprised no fewer than four and possibly five discrete natural populations (provenances) among which there were some marked differences. He postulated that by importing and intercrossing fresh material for future breeding purposes tree breeders could enhance adaptation to local conditions, give greater scope for long-term genetic gains, and confer additional flexibility should utilisation needs change in the future. Accordingly, Bannister (1 963) instigated a large provenanceprogeny trial (Burdon and Bannister, 1973; Burdon etaL., 1992b), which was planted in 1964, -5 and -7 on two contrasting sites in Kaingaroa Forest. This contained 50 seed-parent progenies from each of the five native populations, Aiio Nuevo (Lat. 37"N), Monterey (36.5") and Cambria (35.57, on the Californian mainland coast, and Guadalupe Island (29" and Cedros Island (28" off the 1 New Zealand Forest Research Institute, Private Bag 3020, Rotorua. Baja California Peninsula. The inclusion of Cedros material as P. radiata has been vindicated (Burdon, 1992), although its slower growth posed major experimental problems (Burdon et al., 1992b). This experiment, called the "Genetic Survey", thus sampled almost the full natural range of the species, and was designed to evaluate the genetic variability at the levels of populations, localities within populations, and individual trees. Also included were similar samples from two New Zealand populations (Kaingaroa and Nelson) that were thought to typify local 'land-race' stocks. Spare planting stock was used for three small trials designed purely to compare provenances at three other sites, Gwavas (Hawke's Bay foothills), Santoft (Manawatu sand dunes) and Golden Downs (Moutere gravels) (Shelboume et al., 1979). At the same time, and since then, some inter-provenance hybrids were planted in tests, especially hybrids of the two island provenances with New Zealand material. From the trials planted in the 1960s came a clear picture of the Californian origins of the particular local stocks, predominantly Aiio Nuevo (much the smallest of the Califomian mainland populations) with the balance being Monterey. Thus the representation of the natural range of the species, within those Kaingaroa and Nelson stocks, was very incomplete and unbalanced. There were also indications that the under-represented Monterey provenance had some better soil tolerances, which was consistent with the existence of some infertile sites at Monterey, and with the presence of strong tree-to-tree variation in local stock in soil tolerances (Burdon, 1971, 1976). While the other populations showed considerable adaptive limitations as pure strains (Burdon, 1992), some of the inter-provenance hybrids were very promising, notably those involving Guadalupe and local stock. It was decided to mount a further seed collecting expedition in California to allow far more thorough provenance testing of P. radiata in New Zealand, and to augment the available native-population gene resources. In 1978 a joint Australia-New Zealand expedition took place (Eldridge, 1978). New Zealand's involvement was confined to the Califomian mainland stands of P. radiata, and from that New Zealand obtained unpedigreed seedlots from various locations within the native stands. The collection was used to establish countrywide provenance trials and some larger blocks of gene-resource plantings. This paper is concerned primarily with summarising results from those trials and discussing the future implications of them and the results from other trials of native-provenance material for New Zealand forestry. It is planned to publish the results elsewhere in much more technical detail. Material and Methods The 1978 collection produced seedlots from a total of 13 localities which were believed to represent ecological subdivisions of the populations (four, six and three at AAo Nuevo, Monterey and Cambria respectively). On average, such seedlots represented bulked seed from 40 trees (range 22-70) in a locality, each locality having been grid sampled as far as was practicable. Three regional land-race stocks, 'Kaingaroa', 'Nelson' and 'Southland', were chosen to provide New Zealand controls, these being very . predominantly from select-tree seed collections within supposedly unimproved stands. Of these, the Kaingaroa and Southland

Kraft pulp fibre property prediction from wood properties in eleven radiata pine clones

Abstract: Patterns of variation in density, tracheid cross-section dimensions and kraft pulp fibre dimensions have been estimated in a series of eleven 16-year old radiata pine (Pinus radiata) clones. The aims were to compare wood and pulp fibre measurements and to estimate the efficiency of sampling at breast height (BH: 1.4 metre) for prediction of whole tree wood and kraft pulp fibre properties. Radial sections were examined from six heights in twenty-four trees, representing the eleven clones. Density and tracheid cross-section dimensions were measured at a radial resolution of 50 μm using SilviScan-1, a combined image analyser and scanning microdensitometer. Fibre length distributions of the kraft pulps were measured using the Kajaani FS200, and the cross-section dimensions of dried, unrefined fibres were obtained by image analysis of thin sections. Correlations between BH wood properties and whole-tree estimates were very strong, but there was no significant correlation between tracheid perimeter and wall thickness. It is concluded that tracheid cross-section dimensions may be independently selected in tree improvement programs and that BH sampling is reliable for radiata pine clones.

Effect of elevated CO2 on the utilization of light energy in Nothofagus fusca and Pinus radiata

Abstract: Red beech (Nothofagus fusca (Hook. F.) Oerst.; Fagaceae) and radiata pine (Pinus radiata D. Don; Pinaceae) were grown for 16 months in large open-top chambers at ambient (37 Pa) and elevated (66 Pa) atmospheric partial pressure of CO 2 , and in control plots (no chamber). Summer-time measurements showed that photosynthetic capacity was similar at elevated CO 2 (light and CO 2 -saturated value of 17.2 μmol m -2 s -1 for beech, 13.5 μmol m -2 s -1 for pine), plants grown at ambient CO 2 (beech 21.0 pmol m -2 s -1 , pine 14.9 μmol m -2 s -1 ) or control plants grown without chambers (beech 23.2 μmol m -2 s -1 , pine 12.9 μmol m -2 s -1 ). However, the higher CO 2 partial pressure had a direct effect on photosynthetic rate, such that under their respective growth conditions, photosynthesis for the elevated CO 2 treatment (measured at 70 Pa CO 2 partial pressure: beech 14.1 μmol m -2 s -1 pine 10.3) was greater than in ambient (measured at 35 Pa CO 2 : beech 9.7 μmol m -2 s -1 , pine 7.0 μmol m -2 s -1 ) or control plants (beech 10.8 μmol m -2 s -1 , pine 7.2 μmol m -2 s -1 ). Measurements of chlorophyll fluorescence revealed no evidence of photodamage in any treatment for either species. The quantity of the photoprotective xantho-phyll cycle pigments and their degree of de-epoxidation at midday did not differ among treatments for either species. The photochemical efficiency of photosystem II (yield) was lower in control plants than in chamber-grown plants, and was higher in chamber plants at ambient than at elevated CO 2 . These results suggest that at lower (ambient) CO 2 partial pressure, beech plants may have dissipated excess energy by a mechanism that does not involve the xanthophyll cycle pigments.

Clonal Variation of Wood Chemistry Variables in Radiata Pine (Pinus Radiata D. Don.) Wood

Abstract: Middle lamella lignin concentration (MLLC) was measured for 10 clones (cuttings) of Pinus radiata D. Don., using interference microscopy. Significant variation was observed among clones suggesting a genetic component to this aspect of lignin distribution. The colonel repeatability, an estimate of broad-sense heritability for MLLC, was 0.70 with a clonal coefficient of variation of 9%. The average MLLC was 69% v/v with a minimum clonal average of 58% and a maximum of 77%. Comparison with chemical analysis data revealed significant correlations between MLLC and both arabinose content and xylose content (r = -0.51). There is tentative evidence of a negative relationship between lignin content and MLLC (r = -.42, p = 0.067), which is interpreted as a compression wood effect. The negative correlations with arabinose and xylose suggest that an increased amount of xylan in the middle lamella (arabino-4-O-methyl-glucuronoxylan) is located at higher concentration in the middle lamella region) may be the cause of reduced lignification in this cell wall region. Clonal repeatabilities for various chemical components of P. radiata wood range from 0.32 for glucose content to 0.78 for xylose content. All components except glucose show significant variation among clones.

Genetic parameter estimates for pinus radiata in basque country, northern spain

Abstract: Genetic parameters were estimated for growth and form traits in a 7-year-old progeny trial containing 28 open-pollinated families of Pinus radiata D.Don selected for the Basque Country breeding programme of the species. Observed individual heritabilities were moderate for height (h 2 = 0.20), stem diameter (h 2 = 0.22), branch size (h 2 = 0.14), and branch angle (h 2 = 0.15) and negligible for stem straightness. Stem diameter, height, and branch angle were positively correlated. Branch size had an adverse genetic correlation with growth traits. Genetic gains under index selection strategies were examined. Results from this small-scale trial suggest that is not possible to achieve simultaneous improvements in both growth and branch size.

Forest characteristics affecting the rate of shoot pruning by the pine shoot beetle (Tomicuspiniperda L.) in Pinus radiata D. Don and P. sylvestris L. plantations

Abstract: Summary Different variables, such as altitude and presence of defoliators, were studied in Bizkaia (northern Spain) in order to assess the susceptibility of Pinus radiata (D. Don) and P. sylvestris (L.) stands to Tomicus piniperda (L.) (Coleoptera: Scolytidae). Altitudes higher than 400 m, presence of logs, degree of thinning and incidence of fires, all increased the susceptibility of P. radiata monocultures to shoot attack by T. piniperda. P. sylvestris plantations were more affected at altitudes lower than 400 m and by poor forest hygiene. The presence of the processionary moth (Thaumetopoea pityocampa Den and Schiff.) had a significant effect on the rate of shoot pruning on the trees; vigorous trees and those with bare leader were more affected by the bark beetle attack if T. pityocampa larvae were feeding on their needles, while trees with dominance taken by the side shoots were less attacked when moth larvae were present.

Agroforestry in the Bolivian Altiplano: evaluation of tree species and greenhouse growth of wheat on soils treated with tree leaves

Abstract: Severe environmental problems encountered in the highlands of Bolivia may be remedied through the adoption of agroforestry systems, never before studied adequately in this region. As a first step, seven tree species were tested for growth, survival and health at two elevations in the Bolivian altiplano. Species responded variably with Buddleja coriacea Remy., Pinus radiata D. Don. and Eucalyptus globulus Labill. (at the higher elevation) and E. globulus, Baccharis spp., Robinia pseudoacacia L. and B. coriacea (at the lower elevation), displaying high survival, growth and health. In a related greenhouse study, grain yields of wheat planted in soils amended with incorporated foliage of B. coriacea, P. radiata and E. globulus increased three-fold (0.3 g·plant−1 to >1.0 g·plant−1) over grain yields in unamended soils (B. coriacea > P. radiata = E. globulus). Grain nitrogen (mg·plant−1) increased equally in soils amended with P. radiata and B. coriacea foliage (18 mg N⋅plant−1 to 20 mg·plant−1) but decreased in soils amended with foliage of E. globulus (18 g·plant−1 to 9 g·plant−1).

Assessment of plantation productivity in first and second rotations of Pinus radiata in New South Wales.

Abstract: Summary Productivity of the first and second rotations of Pinus radiata (D. Don) plantations was evaluated at seven sites on four parent rock types in New South Wales. The comparisons were made at ages 11, 14, 18, 19, 20 and 24 years using data from first rotation (RI) and second rotation (R2) stands collected from (1) adjacent compartments, (2) the same compartment and (3) the same plots. The results show no overall decline in the productivity of R2 stands, although there were some fluctuations. Mean dominant height, diameter at breast height, basal area and stand volume of R2 stands were generally greater than those of R1 stands. The mean increases in stand basal area and volume were about 13% and 18% respectively. The most significant increase in productivity was found in young stands but the advantage declined after age 20. The superior productivity of R2 stands was generally attributed to better site preparation, seed sources, weed control and fertiliser applications.

Compression-rolling reduces Kiln brown stain in radiata pine sapwood.

Abstract: Kiln-drying of radiata pine (Pinus radiata) sapwood often causes the formation of a brown discoloration, commonly called kiln brown stain. Kiln brown stain develops just under the wood surface in a thin layer but subsequent machining of the lumber exposes the stain. The occurrence of kiln brown stain has caused substantial loss in revenue in New Zealand's high-value radiata pine export markets. In this study, the effect of compression-rolling of radiata pine prior to kilning was investigated as a potential method to control the formation of kiln brown stain, along with its effect on thickness shrinkage and drying time. The results of the study demonstrated that regardless of kiln schedule, compression-rolling significantly reduced the formation of kiln brown stain in the kilning of radiata pine, but increased drying time. In the drying ofradiata pine at 90/60°C, rather than at 71/60°C, compression-rolling significantly increased thickness shrinkage from 4.9 to 6.0 percent. The mechanisms of compression-rolling on kiln brown stain formation in the drying of radiata pine are discussed.

Comparative nutrient responses by Pinus radiata, Trifolium repens, Dactylis glomerata, and Hieracium pilosella on a Mackenzie Basin outwash plain soil

Abstract: The nutrient responses by a pine (Pinus radiata), a pasture grass (cocksfoot, Dactylis glomerata), a pasture legume (white clover, Trifolium repens), and a hawkweed (mouse‐ear hawkweed, Hieracium pilosella), were compared in a pot trial using a Mackenzie Basin outwash plain soil. Responses to nitrogen (N) and phosphorus (P) were tested alone and in combination, whereas responses to sulphur (S), potassium (K), magnesium (Mg), micronutrients, and lime were tested only in the presence of both N and P. All species responded to N and P, and to S and lime in the presence of N and P, but none responded to K, Mg, or micronutrients. N was the major deficient nutrient for the non‐legume species, with grass and hawkweed responding by 700% in the presence of added P, whereas pine showed a much smaller (56%) response. Clover showed the greatest response to P. Hawkweed showed the smallest response to P, but the greatest responses to S and lime. While pine responded to the same nutrients as the herbaceous speci...

Genotypic variation in symptoms of upper mid-crown yellowing and cyclaneusma minus in a pinus radiata stand

Abstract: In New Zealand, low needle retention in Pinus radiata D.Don is often associated with infection by a needle-cast fungus, Cyclaneusma minus (Butin) DiCosmo et al., and with a condition known as upper mid-crown yellowing (UMCY). Variability in the expression of these two disorders is known to be controlled by both environmental and genetic factors. In order to estimate the degree of genetic control, adjacent seedlings and clonal trees (six clones selected for vigour in the nursery) were assessed at age 22 years for symptoms of UMCY and of C. minus in stands thinned to three final-crop stocking rates. Estimates of genotypic and non-genetic variance and of broad-sense heritability (ratio of genotypic to phenotypic variance) were obtained in two ways: (a) by subtracting the observed within-clone variance from the phenotypic variance of seedling trees, and (b) by directly estimating clone-to-clone variance. Values obtained by these methods agreed well with each other and with earlier estimates made in a nearby seed orchard. Factors related to method of propagation and physiological ageing are therefore unlikely to inflate clonal variation. Clones may be the more cost-effective indicator for UMCY studies. Genotypic variance in resistance to both disorders is considered to be sufficiently high (at least 64% for UMCY and 44% for C minus) to warrant consideration in silvicultural practices.

Pinus radiata growth benefits from spot weed control in kinleith forest

Abstract: The effects of combinations of area treated with herbicide and duration of spot weed control on radiata pine (Pinus radiata D. Don) growth were examined. Two years after planting, large differences in tree volume were attributable to treatment even in trees that had received only first year weed control. After three years, height and diameter growth were both greatest where complete weed control had been maintained for at least 2 years. The most practical treatment for this site would be a spot diameter of 1.6 - 2.0 m, maintained weed-free for at least two years.

Effect of some common weed species on pinus radiata growth at a dry south island site

Abstract: Reductions in radiata pine (Pinus radiata D.Don) growth caused by a range of common weed species were measured at a site where water availability was known to limit tree growth. Radiata pine seedlings were grown for 3 years on their own or with volunteer herbaceous broadleaves, broom, gorse or browntop. Water and nutrient levels were varied by factorial +/- irrigation and fertiliser treatments. Radiata pine stem volume was reduced in the presence of all four weed types. Herbaceous broadleaf weeds had the greatest effect on tree growth, gorse had the smallest effect, and broom and grass were intermediate. Water supply was thought to have a major effect in determining the influence of weeds on tree growth.

Boron nutrition of radiata pine plantations in Australia

Abstract: Extensive areas of radiata pine (Pinus radiata) plantations in Australia, New Zealand and Chile are low in boron (B) and deficiency is recognised as the most common micronutrient limitation in these forest plantations. Knowledge of the relationships between the incidence of B deficiency and site, stand and climatic factors, together with results from fertilizer trials, enables the formulation of pre-emptive B fertilizer treatment for plantations identified to be at risk. The primary objective of applying B fertilizer is to prevent a marked falldown in the expected levels of plantation timber yield and value. Both the severity and extent of B deficiency symptoms are related to periods of low water availability (low rainfall). The actual availability of soil water cannot be managed directly, however, the probability of periods of low rainfall can be determined from historical records and the level of risk of B deficiency estimated. This process is a component of systems to determine requirements for early or later age B fertilizer treatments in plantations.

Does contact of pinus radiata slash with soil influence post-harvest nutrient losses?

Abstract: Although nitrogen dynamics during litter decay have been studied extensively, little work has addressed the contribution of needles in harvest residue to nutrient losses. We examined the decay of Pinus radiata D. Don needles on slash and not touching the soil, from compartments clearfelled between 4 months and 4 years previously in Himatangi and Santoft Forests. Fresh foliage was also collected from 25-year-old P. radiata, together with soil F, H, and A horizons. The needles and soil samples were incubated, both separately and combined, in suction vessels and leached regularly with water. Most nitrogen was leached from the 4-month and 4-year needles, and amounted to about 8% of the total nitrogen; little nitrogen was leached from fresh foliage. Nitrate-nitrogen was the dominant form of nitrogen leached from the 4-year needles, whereas ammoniumnitrogen was dominant from the 4-month and 1 -year needles. More nitrate-nitrogen was produced when the 4-month needles were incubated on top of F, H, or A horizon samples which increases potential for leaching. These data were consistent with field results from lysimeters showing nitrate-nitrogen was leached under 2-year-old windrows and raked soil in Santoft Forest. Net phosphorus mineralisation occurred readily in the older needles and mineral soil, and with time could contribute to the labile pool of phosphorus. Our results suggest that post-harvest losses of nitrogen could increase when large amounts of slash remain in stockpiles. Water-soluble carbon compounds were released from all the foliage samples. Differences in nitrogen losses and forms of nitrogen mineralised are likely to be related to changes in quality of carbon in needles after harvest.

The morphology and development of Lotus uliginosus and Trifolium subterraneum under Pinus radiata canopy in southern Chile

Abstract: A split-plot experiment was conducted in southern Chile to study the effects of tree cover and level of fertilizer application at establishment on the morphology and development of the legumes Lotus uliginosus and Trifolium subterraneum, when sown in conjunction with Festuca arundinacea as the companion grass. Trees were 13-year-old Pinus radiata, spaced at 4 × 12.5 m intervals and with a mean canopy diameter of 4.8 m. At 150 days after sowing the total area of Lotus leaves and length of Lotus stems/plant were not affected by tree cover. Individual plants had fewer stems but they were longer. For Trifolium, despite large increases in individual petiole length and leaf area, total petiole length and leaf area/plant were reduced by tree cover because of a reduced number of petioles/plant. At 275 days after sowing, the number and weight of Lotus components/ha was not affected by tree cover, although companion grass development was reduced. By 640 days the number and weight of Lotus components/ha was reduced but only to the same degree as the companion grass. Trifolium plant development, and in particular seed yield, was affected by tree cover at 275 and 640 days and to a greater extent than Lotus or the companion grass. A high level of fertilizer application at establishment induced a greater development of both legumes at 275 days, but by 640 days the effects were much reduced. It is concluded that both Lotus uliginosus and Trifolium subterraneum respond to tree cover by increasing stem length and leaf area, but that in situations with low soil fertility, the development of Lotus is less affected by tree cover than Trifolium.

Effects of xylooligosaccharides on suspension-cultured cells and protoplasts of Pinus radiata

Abstract: The effects of xylooligosaccharides isolated from the cell walls of Betula platyphylla var. japonica on cells and protoplasts of Pinus radiata were examined. The addition of a semi-purified mixture of xylooligosaccharides at a concentration of 5µg.ml−1 promoted elongation of cultured cells, whereas the neutral fraction of this mixture had no effect; a similar effect was seen in the presence of conditioned medium. The unfractionated mixture of xylooligosaccharides was also found to enhance the viability of protoplasts prepared from cell cultures of Pinus radiata in a concentration dependent manner, highly similar to the effect provided by addition of medium conditioned by pine cells. Such effects are considered to be due to the addition of components that play a structural role in the cell wall of pines. It is inferred that the acidic components of the xylooligosaccharide mixture derived from t Betula are responsible for this effect in the distant pine species. It is speculated that acidic xylooligosaccharides operate either by replacing, or mimicking, the natural cell wall components required for growth and development of pine cultured cells.