An Acoustics Operations Study for Loblolly Pine (Pinus taeda) Standing Saw Timber with Different Thinning History
There is currently a request from landowners in southeastern USA to provide a nondestructive tool that can differentiate the quality between stands of 25 and 30 years of age subjected to different thinning treatments. A typical site with various thinning regimes was used to vary the wood quality and to determine whether acoustics had the ability to separate for stiffness differences at a given age and local geography. A stand at age 29 with three different spacing (prior thinning) levels was chosen. Three hundred trees (100 per treatment) were randomly selected and acoustically tested for sound velocity using the Time-of-Flight (ToF) method for unthinned, thinned, and twice-thinned stands, respectively. The key finding of the study was that the estimated stiffness of the previously thinned treatments was actually greater than that of the unthinned group, despite having diameters as much as 28% larger. During a forest cruise, knowing that a higher-diameter stand is similar or higher in stiffness could raise the dollar value and harvest priority.
GENETIC IMPROVEMENT OF FIBER LENGTH AND COARSENESS BASED ON PAPER PRODUCT PERFORMANCE AND MATERIAL VARIABILITY – A REVIEW
Improvement of specific gravity through tree breeding was an early choice made in the mid 20th century due to its ease of measurement and impact on pulp yield and lumber strength and stiffness. This was often the first, and in many cases, the only wood quality trait selected for. However, from a product standpoint, increased specific gravity has shown to lower many paper strength and stiffness properties and has been assumed to be directly attributable to increased fiber coarseness. As a result, it is currently not clear which fiber trait would best benefit a tree improvement program for paper products. This review found coarseness to be perhaps more important to paper strength and stiffness whereas tracheid length showed better promise from a breeding point of view due to its independence from specific gravity. However, both traits possessed strong heritability and influence on product performance and thus both would be beneficial to breed for depending on organizational goals and end product mix. The objective of this paper is to review and prioritize coarseness and tracheid length from both an end use and raw material perspective. To aid in prioritization, the variation, correlation, and heritability of both traits were reviewed along with significant genetic and phenotypic correlations. Variation trends within and between families as well as within a tree were reviewed.
Age-age correlations for tracheid length and wood density in Pinus sylvestris
The existence of strong genetic correlations between traits at an early age and at an adult age should shorten the generation turnover of tree breeding populations and render forest tree breeding more effective. Genetic age-age correlations for tracheid length and wood density were estimated in Scots pine (Pinus sylvestris L.) and the efficiency of early selection for these traits was evaluated. Increment cores of 10-mm diameter were collected from trees of 106 full-sib families in a progeny trial located in southeastern Sweden and consisting of controlled matings between 30 parent trees. The additive genetic age-age correlations were consistently close to unity for all traits and ages studied. The additive genetic variance differed significantly from zero for all traits. The dominance variance was zero for tracheid length and small and insignificant for wood density. The heritabilities varied between 0.3 and 0.5. The genetic gain per year for both tracheid length and wood density was largest if selection...