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Huonville, Australia

Drew D.M.,CSIRO | Downes G.,Forest Quality Pty. Ltd
Trees - Structure and Function | Year: 2015

Key message: A model of wood formation processes in pines predicted 80 % of mean wood density variation from inputs of carbohydrate allocation and tree water status from several varied sites. Abstract: Numerous factors determine how wood properties vary as a tree grows. In order to model wood formation, a framework that considers the various xylogenetic processes is required. We describe a new model of xylem development and wood formation in pines (parameterised for the commercially important species, Pinus radiata D. Don). In this paper, we use as inputs simulated daily data from the CaBala stand growth model which, in turn, takes into account site and daily weather conditions, and silviculture. It incorporates a first attempt at predicting microfibril angle (the angle of cellulose microfibrils relative to the vertical axis of the cell, MFA) based on metrics of cambial vigour and carbohydrate allocation. It also predicts tracheid dimensions and wall thickness, and from these data, wood density. Pith-to-bark and intra-annual variation in predicted wood properties was realistic across a wide range of site types, although juvenile wood properties were weakly predicted. The model was able to explain 50 % of the variation in outerwood MFA and 70–80 % of the variation in outerwood and mean sample wood density respectively, from 17 study sites. The model, early results from which are very promising, provides a useful framework for testing concepts of how formation occurs, and to provide insights into areas where further research is needed. © 2015, Springer-Verlag Berlin Heidelberg. Source

Downes G.M.,Forest Quality Pty. Ltd | Downes G.M.,Cooperative Research Center forestry Ltd. | Downes G.M.,National Center for Future Forest Industries | Harwood C.,Cooperative Research Center forestry Ltd. | And 4 more authors.
European Journal of Wood and Wood Products | Year: 2014

NIR predictions of cellulose content and stiffness (modulus of elasticity, MOE) from spectra collected from the radial longitudinal surface of Eucalyptus globulus wood were found to be reliable indicators of zones of non-recoverable collapse associated with the presence of tension wood. Radial sections from 25 quarter-sawn boards cut from plantation-grown E. globulus trees in Spain were scanned to generate radial profiles of NIR-predicted wood properties at 2 mm increments. These boards manifested a range of non-recoverable collapse features, from no collapse to one or more severe collapse bands. Collapse bands occurred where NIR-predicted cellulose content and MOE exceeded threshold levels of 50 % and 25 GPa, respectively for more than four consecutive millimetres. A non-recoverable collapse indicator provided a clear predictor of non-recoverable collapse. A NRCI value ≥100 for a consecutive interval of at least 4 mm successfully predicted all ten NRC bands with shrinkage ≥10 % of board thickness. The potential applications of this tension wood detection method are discussed. © 2014 Her Majesty the Queen in Right of Australia. Source

Zweifel R.,Swiss Federal Institute of forest | Zweifel R.,CSIRO | Drew D.M.,CSIRO | Schweingruber F.,Swiss Federal Institute of forest | And 2 more authors.
Functional Plant Biology | Year: 2014

The state-of-the-art interpretation of stem radius changes (DRTotal) for tree water relations is based on knowledge from mostly slow growing tree species. The ratio between diurnal size fluctuations of the rigid xylem (DRXylem) and the respective fluctuations of the elastic bark (DRBark) is known to be small (<0.4) and is of importance for the localisation of water storage dynamics in stems. In this study, fast growing Eucalyptus globulus Labill. in Tasmania were investigated by point dendrometers in order to investigate tree water relations. Unexpectedly, DRXylem was found to be the main driver of DRTotal with the bark acting as a passive layer on top of the fluctuating xylem under most conditions. Accordingly, the ratio between the diurnal fluctuations of the two tissues was found to be much higher (0.6-1.6) than everything reported before. Based on simulations using a hydraulic plant model, the high tissue-specific elasticity of the Eucalyptus xylem was found to explain this atypical response and not osmotically-driven processes or species-specific flow resistances. The wide zone of secondary thickening xylem in various stages of lignification is proposed to be an important component of the high wood elasticity. The tissue acts as additional water storage like the bark and may positively affect the water transport efficiency. © 2014 CSIRO. Source

Downes G.,Forest Quality Pty. Ltd | Harwood C.,CSIRO | Washusen R.,University of Melbourne | Ebdon N.,CSIRO | And 3 more authors.
Australian Forestry | Year: 2014

Wood properties of 10-year-old trees in Eucalyptus globulus plantations at three sites in Western Australia were examined. Silvicultural treatments applied at age two years were stocking (unthinned, 1250 stems ha-1; thinned to 600 stems ha-1 or 300 stems ha-1) and nitrogen fertiliser application (0 or 250 kg ha-1 elemental nitrogen) in factorial combination. The three sites differed markedly in their annual rainfall (620-1100 mm), open-pan evaporation and soil water-holding capacity. Wood cores were collected at breast height from a total of 263 trees (~15 trees for each site-by-treatment combination), and radial samples prepared for analysis by SilviScan to produce radial profiles of air-dry density and microfibril angle (MFA) and modulus of elasticity (MOE), and by radial near infrared (NIR) surface scanning to produce radial profiles of NIR-predicted Kraft pulp yield (KPY) and cellulose content (CC). Sampling interval was 0.025 mm for density and 5 mm for the other properties. For wood property mean values (i.e. wood property averages of each pith-to-cambium sample), sites differed significantly only in air-dry density. The Boyup Brook site, which had low annual rainfall, the lowest climate wetness index and soil water-storage capacity and the slowest diameter growth, had the highest mean wood density (648 kg m-3), while Scott River, with the highest rainfall, had mean density that was 10% lower. The Wellstead site (low rainfall but highest soil water-storage capacity) was intermediate for density. The only other significant differences for mean wood properties were caused by fertiliser addition, which reduced NIR-predicted KPY from 54.6% (without fertiliser) to 54.1% and predicted CC from 43.7% to 43.1%. Clear radial trends were evident for all wood properties. Density, MOE, KPY and CC all increased from pith to the cambium, while MFA declined. From the innermost (pith) 10% to the outermost (cambial) 10% of the radius, density increased on average by 21%, MOE by 103%, KPY by 9% and cellulose by 11%, while MFA declined by 47%. NIR calibrations developed using the SilviScan and NIR spectral data explained 71% of variance in MOE for an independent set of radial wood samples of E. globulus from Victoria, but less than 50% of variance for density and MFA. Implications for paper pulp and veneer manufacture are briefly considered. © 2014 CSIRO. Source

Griffin A.R.,University of Tasmania | Twayi H.,The Innovation Hub | Braunstein R.,The Innovation Hub | Downes G.M.,Forest Quality Pty. Ltd | And 2 more authors.
Appita Journal | Year: 2014

Pulping properties and fibre characteristics of wood from eight-year-old ramets of 6 diploid and 5 tetraploid clones of Acacia mangium grown in Vietnam are reported. Individual clones were represented by two or three ramets. While kraft pulp yield at kappa 20 was very similar for diploid and tetraploids clones, tetraploid clones produced pulp with significantly longer (883 urn) and wider (20.0 μrn) fibres, compared to the diploid clones (683 urn and 15.6 μrn). The tetraploid cell wall thickness was greater, resulting in a coarser pulp. Pulmac fibre strengths of the tetraploid were greater than those of the diploid, although their fibre bonding area was lower. The kraft pulp of the best of the tetraploid clones had higher bulk, porosity and tear strength at constant tensile than pulp from a mix of diploid clones and was similar in these traits to softwood pulp. Source

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