S. Stringer

Bio: S. Stringer is an academic researcher. The author has contributed to research in topics: Tracheid. The author has an hindex of 1, co-authored 1 publications receiving 113 citations.

Rapid measurement of variation in tracheid transverse dimensions in a radiata pine tree

Abstract: Variation in tracheid cross-section dimensions has been mapped in a 19 year old radiata pine tree. An instrument recently developed for the rapid estimation of transverse tracheid dimensions was used for the analysis. Sixty radii (four directions at each of fifteen heights) were processed. Variation was mapped for properties important to the pulp and paper industry: wood density, tracheid perimeter, coarseness and wall thickness. In this tree, coarseness, wall thickness and density trends were approximately linear from pith to bark, and the rate of rise was similar at all sampling heights. As a result, variation of these properties in the three was approximately cylincrically symmetric. Average coarseness, density and wall thickness fell by 25% from the 0.8 metre level to the 20 metre level in the tree. Average tracheid perimeter was almost independent of sampling height. At breast height, coarseness rose by 86% from pith to bark (350 to 650 μg m -1 ), density rose by 45% (380 to 550 kg m -3 ) and wall thickness by 57% (2.1 to 3.3 μm). Unweighted breast height core properties for this tree were similar to volume-weighted whole tree properties above breast height. Correlations between properties such as coarseness and wall thickness were strong when ring averages or trends were considered, but poor within individual tree rings. Understanding of the mechanisms of short term regulation of tracheid properties should allow increased selectivity in the silvicultural and genetic control of individual properties

Methods for measuring stiffness of young trees

Abstract: clones with high modulus of elasticity (MOE). Various ways of measuring MOE are examined: traditional static bending, axial compression of bolts, existing sonic methods, as well as a tool specifically configured for resonance on short bolts. Wood characteristics and microfibril angle are measured on discs taken from each tree. Results show a good correlation between acoustic and static measurements of modulus of elasticity. Moreover, the selected seven radiata clones differ in stiffness by a factor of two, and much of this variation seems to relate to differences in microfibril angle. The results validate the assumption that there is potential to improve wood stiffness of radiata pine genetically. This work does not offer definitive solutions but explores a number of approaches that could be utilised as a selection tool in tree breeding for better product performance of radiata lumber. Here, development of methods based on acoustics is shown to assist in the necessary mass screening of clones for stiffness properties.

Direct Effects of Wood Characteristics on Pulp and Handsheet Properties of Eucalyptus globulus

Abstract: Summary Eucalyptus globulus Clones Path analysis Wood quality Wood density Fibre length Microfibril angle Handsheet Tensile index Tear index Paper strength Pulp yield Fibre length, microfibril angle and wood density were measured in eight-year-old Eucalyptus globulus clones planted on three different sites. Samples were chipped and pulped, and the pulps beaten prior to preparation of 60g/m 2 handsheets. Eleven physical handsheet properties, together with pulp freeness, were measured using standard methods. Direct relationships between wood properties and pulp/paper properties were studied using path analysis. Fibre length had a strong, direct effect on tear index, bending stiffness, freeness, pulp yield and active alkali consumption. Wood density was a strong predictor of most handsheet properties: high density woods produced bulkier, more porous sheets with higher bending stiffness, while lower density woods produced smoother, denser sheets with higher tensile strength. The effect of microfibril angle was small and more evident in handsheets made from beaten pulp.

Near infared spectroscopy in the forest products industry

Abstract: Improving manufacturing efficiency and increasing product worth requires the right conbination of actions through-out the manufacturing process. Many innovations have been developed over the last several decades to achieve these goals. Innovations typically work their way backwards in the manufacturing process, with an increasing level of monitoring occurring at the end of a production line. There exists, however, an ever-increasing array of tools available to forest products manufacturers that allow rapid assessment of material and product variables throughout the manufacturing process. A technology that shows great potential in all facets of material assessment is near infrared (NIR) spectroscopy. The potential for NIR technologies has not gone unoticed by the wood research community and there are scores of national and international laboratories developing appropriate applications. The rapid assessment of solid wood properties using NIR spectra is a fast-growing field that has broad implications in relation to wood quality and, ultimately, tree improvement. NIR as a means of online monitoring during the manufacturing process has also spured many laboratories to examine potential applications for wood composites. It is probable that this type of monitoring will lead to increases in efficiency and profits.