Showing papers on "Pinus radiata published in 1980"

Root configuration and root regeneration in pinus radiata seedlings

Abstract: Root configuration of radiata pine (Pinus radiata D.Don) seedlings in the nursery was examined in relation to nutrient supply, and the configuration of the regenerated root system after transplanting was examined in relation to seedling treatment and soil temperature. In the nursery an increase in shoot growth owing to high soil fertility was not accompanied by a similar response in root growth, resulting in a high shoot-root ratio. High soil fertility decreased mycorrhizas. Nitrogen and phosphorus deficiencies reduced the weights of the shoot and root but had little effect on root configuration. Changes in root weight can lead to faulty conclusions about root development. Even when nitrogen deficiency was extreme the root system possessed a remarkable ability to adjust the number and length of first and second order laterals, and so lessen the effect of stress on configuration. Similar, but lesser, effects were found under phosphorus deficiency. This ability may be important for the survival of seedlings in naturally regenerating forests. A decrease in the mean extension rate of root members seems to be the major reason for the reduction in root length in nutrient starved plants. The configuration of roots regenerated after transplanting is closely related to the initial configuration of the planting stock, the number and length of the first order laterals capable of regeneration being the most critical basic frame­ work for the new root network. However, the number of first order laterals appears to be not amenable to manipulation by nursery management practices. Radiata pine seedlings developed strategies to cope partly with the effects of nutrient deficiency or low temperature on root configuration.

Removal of phosphorous in logs when harvesting Eucalyptus delegatensis and Pinus radiata forests on short and long rotations

Abstract: Summary The quantity of phosphorus (P) accumulated in the wood and bark of tree stems, and which is removed from the forest by harvesting, has been estimated for native Eucalyptus delegatensis stands and Pinus radiata plantations on the southern tablelands of New South Wales. The rates at which P is accumulated and removed in logs are compared for the two species grown on either short (20 yr) or longer (40 yr for P. radiata, 60 yr for E. delegatensis) rotations. The comparison showed that in stands which are older than about 7 years, 3–5 times more P is removed from the forest when harvesting a unit weight of P. radiata log (wood and bark) because this species contains more sapwood (which persists for 17–25 years before being transformed to heartwood) than E. delegatensis (7 years of sapwood), and the concentration of P is much greater in sapwood than in heartwood. The concentration of P is more than three (and can be ten) times greater in the heartwood of P. radiata than it is in E. delegatensis. Shorten...

Fate of 15N urea fertilizer applied to a recently thinned radiata pine stand on a pumice soil.

Abstract: In 1961 a large lysimeter was built in Kaingaroa Forest; together with the surrounding area it was planted with radiata pine (Pinus radiata) In the spring of 1974 the 13-year-old stand of trees was thinned, and 3 months later Nenriched urea was applied to the Taupo silty sand in the lysimeter and in its immediate surround at a rate equivalent to 200 kg N/ha In the following 3 years no apparent loss of N by leaching and no change in the rate of leaching of other nutrients was recorded The concentrations of KCl-extractable NH4-N in the surface soil layers showed marked increases 1 week after the fertiliser application, and there were further increases between weeks 2 and 4 After 38 weeks, concentrations had returned to pretreatment levels Increased N03-N concentrations were detected after 2 weeks; these were maintained for the duration of the experiment All of the applied N was still present in the litter and top 30 cm of soil 2 weeks after application The proportion of applied N in the litter and top 30 cm of soil dropped to 60% after 4 weeks and later stabilised at about 50% It is suggested that tree uptake accounted for a large part of this loss

Vegetation changes as a result of invasion of forest on krasnozem by Phytophthora cinnamomi.

Abstract: Disease caused by Phytophthora cinnamomi was studied for 5 years in native and planted forest growing on krasnozem in the northern foothills of the Great Dividing Range at Narbethong, 100 km northwest of Melbourne. Changes in species composition were recorded for three sites carrying mature dry sclerophyll forest of Eucalyptus obliqua and Eucalyptus radiata, young plantations of E. obliqua, and young plantations of Pinus radiata. The mature ecualypts were diseased in 1974 and now are gradually dying. The young E. obliqua showed greater resistance than the older trees to the pathogen but infected trees were characterized by lower height, small leaves with reduced water potential, and an increased susceptibility to the leaf spot fungus Aulographina eucalypti. Susceptible understorey species such as Tetratheca ciliata and Epacris impressa died, but seedling regeneration of these has since occurred on one site. No species has disappeared from all three sites but T. ciliata and Daviesia latifolia almost disappeared from site 2, and the total number of plants was reduced. Species such as Leptospermum juniperinum and Platylobium formosum developed fluctuating cycles of chlorosis and die-back followed by either recovery or death. Resistant plants such as sedges, grasses and Acacia dealbata invaded the diseased forest. During the first year of the investigation 13% of the 4-year-old Pinus radiata died, but this particular site was well drained, warmer and drier than the others and the surviving pines later grew vigorously and crowded out other species. Symptoms are no longer evident on this site. The future status of the mature forest and the probable effects of disease on the young E. obliqua plantation are discussed.

Effect of thinning on the distribution and biomass of foliage in the crown of radiata pine

Abstract: Replicated plots in a 15-year-old plantation of radiata pine (Pinus radiata D. Don) of basal area approximately 40 m 2 /ha were thinned from below to approximately 11, 18, 23, and 28 m'-/ha respectively. The plots were re-thinned periodically thereafter to these same basal areas; one replicate of plots was retained relatively unthinned. Regression equations relating needle dry weight to branch cross-sectional area were developed and used to examine the distribu­ tion of foliage of various ages within the crowns. In the upper crown (70-80% height decile and above), the percentage of 1-year foliage increased acropetally from 52 to 75% whereas that of 2-year and 3-year and older foliage decreased slightly (28 to 22%) and markedly (20 to 3%) respectively. In the middle and lower crown, i.e., all deciles below the 70-80% decile, the distribution of foliage across age classes was approximately constant at 37% (1-year), 28% (2-year), and 36% (3-year and older). The combined biomass of 1- and 2-year leaves within the whole crown averaged 73% of total leaf biomass under all thinning regimes. Though stand density had little effect on proportionate distribution of foliage by position in the crown or leaf age, the total amounts of foliage varied greatly. Total foliage biomass ranged from 4.9 to 11.3 tonnes/ha and annual foliage production from 2.4 to 4.3 tonnes/ha in stands of mean stand density ranging from 15m 2 /ha (biomass) or 21 m 2 /ha (annual production) to 46 m 2 /ha.

Insect pests of Pinus radiata plantations: present and possible future problems

Abstract: Summary There are as yet few insect pests in the Pinus radiata plantations of Australia, New Zealand, Chile and Europe. The present insect pests of these plantations are discussed and a comparison is made between those occurring in the Northern and Southern Hemispheres. Forecasts of possible future insect problems are made based on past experience, risks of accidental importations, and current forestry practices.

An Assessment of Windfall Damage to Pinus radiata in the Bosboukloof Experimental Catchment

Abstract: The Bosboukloof catchment is part of a multiple watershed experiment at Jonkershoek. The catchment is afforested with Pinus radiata D. Don and has a history of windfall damage. This report is an assessment of the very severe damage caused by two windstorms in 1977. Weather conditions before and during each storm are examined as causes along with abnormal silvicultural history. Windfall damage was severe enough to necessitate the c1earfelling of 8,13 ha of P. radiata. Stream-flow is expected to increase by approximately 27 mm/yr (1,92%) as a result of the reduction in afforested area. Management adjustments are necessary to reduce windfall damage in future rotations.

Bole growth patterns of Pinus radiata D. Don in relation to fertilisation, bending stress, and crown growth.

Abstract: Radial increment patterns were studied in 18 stand-grown Pinus radiata trees after thinning and fertilisation Patterns in ring width increment along the bole were significantly correlated with bending stress, crown growth activity, and their interaction Bending stress appeared to regulate growth in the upper 20% of the bole and crown growth factors dominated in the lower bole No significant effect of fertilisation was found in patterns of stress or crown growth activity in any of the years analysed although a large shift in form factor associated with fertilisation was noted in one year

Development of internal graft incompatibility symptoms in Pinus radiata D. Don.

Abstract: Detailed anatomical study of P. radiata grafts revealed that phloem tissues of incompatible grafts are abnormally thick. Grafts with thick phloem often displayed \"pitted\" stems. Thickened bark resulted jointly from overproduction of sieve cells and underproduction of tracheids. Normal pattern of phloem differentiation was altered and phloem areas formed which lacked axial parenchyma. Other internal symptoms in union zones of some incompatible grafts were suberisation and necrosis of cortex cells, excessive tannin accumulation indicated by abnormally darkly-stained bark tissues, formation of abnormal parenchyma in the xylem, and atypical dilation of horizontal ray cells and axial parenchyma. Increasingly more grafts developed symptoms of incompatibility as graft age increased: 10%, 24%, 35%, 54%, and 72% of 1-, 3-, 5-, 8-, and 13to 18-year-old grafts, respectively. Possible interactions between occult viruses and true stockscion incompatibility may be responsible for the graft survival and vigour problems.

Pentachlorophenol fails to protect seedlings of Pinus radiata from Armillaria root rot.

Abstract: Treatment of container grown Pinus radiata seedlings inoculated with Armillariella novac-zelandiae or A. limonea with sodium pentachlorophenate and/or pentachlorophenol gave no reduction in seedling infection or mortality. Seedling infection and mortality increased and vigor decreased in some treatments.

Root and shoot water potentials in stressed pine seedlings

Abstract: Water potential differences were measured between the soil, roots and shoots of Pinus radiata D.Don and P. brutiaTen. seedlings grown under controlled climatic conditions. Root growth under stress was strongly affected by climatic treatment, particularly temperature. In both species, water potentials in the cool climates were always less negative than in the warm climates. The relations between shoot (^x) and root (^r) water potentials were analysed; regression of ^x over ^r with increasing water stress was linear in Pinus radiata and curvilinear in P. brutia. The implications of the findings are discussed.

Morphactin transport and metabolism in tree bark tissues: comparative studies in vitro.

Abstract: Bark banding of morphaction is an effective means of controling stem elongation in Pinus radiata D. Don (Monterey pine) but not Juglans regia L. (English walnut). Diffusion coefficients of 14C-labeled morphactin across excised disks of tree bark, measured in specially designed diffusion chambers, were 11 to 85 fold greater in pine than walnut. In seedlings of comparable age, the suberin layer of walnut bark is much thicker than that of pine; if the layer is removed, diffusion of 14C-morphactin is enhanced 39-fold in pine and 285-fold in walnut. Morphactin applied to the bark as an ester is rapidly hydrolyzed to its carboxylic acid derivative in both pine and walnut. This conversion occurs rapidly in the bark of both species and does not appear to limit the rate of morphactin movement across the bark. These results suggest that diffusion across the suberin layer and not metabolism limits morphactin transport across the bark.