Variation and Genetic Control of the Heartwood, Sapwood, Bark, Wood Color Parameter, and Physical and Mechanical Properties of Dipteryx panamensis in Costa Rica

The Dipteryx genus has a natural distribution throughout several tropical countries in Latin America. This taxon has several tree species, all recognized for their high-density wood. The objective of this research was to study the variation and genetic control of several wood properties, including bark, sapwood, heartwood, green density (GD), specific gravity (SG), moisture content in green condition (MC-G), and mechanical properties, in a Dipteryx panamensis provenance/progeny test at 8 years old. The results showed that bark varied little among families and provenances, but heartwood (diameter and percentage) showed high genetic variation. SG and MC-G showed significant variation between provenances and families, while GD showed little variation. Among the mechanical properties evaluated, the greatest genetic variation was observed in the MOR in bending and shear stress. Families from the Coope San Juan provenance registered the highest values in all wood properties investigated, and families from Puerto Viejo obtained the lowest. Family heritability and the coefficient of genetic variation exhibited high values in heartwood/sapwood and the MOR in bending (h2 > 0.9 and CV > 20%) and lower values in SG, MC-G, compression stress, and shear stress. D. panamensis wood properties have a high potential to be improved through breeding programs.

Tree dimension and environmental correlates of heartwood content in Siamese rosewood (Dalbergia cochinchinensis)

Meunpong P, Penboon C, Kuasakun N, Wachrinrat C. 2021. Tree dimension and environmental correlates of heartwood content in Siamese rosewood (Dalbergia cochinchinensis). Biodiversitas 22: 3297-3303. Siamese rosewood (Dalbergia cochinchinensis) is considered amongst the prime timber varieties in high demand with the wood fetching high prices in the international timber market. Therefore, illegal logging and smuggling of Siamese rosewood from natural forests poses a severe problem in Thailand. Heartwood and its content is the most valuable part of Siamese rosewood, which in practice, cannot be measured directly in living trees. Hence, we investigated the relationship between the heartwood content of Siamese rosewood, and tree dimension and environmental characteristics across eleven plantations throughout Thailand construct a model for predicting the heartwood content using specific environmental variables. The results indicate that there were differences in the mean annual increment of all measurement parameters (d0, d30, dbh, and total height of a tree) across eleven plantations studied. However, we did not find any statistically significant differences between the increments in heartwood diameter. Furthermore, we found that suitable location for Siamese rosewood plantation could result in doubling of growth rate. We report that dbh was the most relevant variable and could be used as a predictor for heartwood content. In terms of environmental variables, soil properties at top layer that affect the heartwood content were particle density, organic matter, and silt particles. Using the resulted equation formulated in this study may be useful when planning areas for suitable plantations of Siamese rosewood in Thailand.

Acacia melanoxylon in Argentina: heartwood content and its relationship with site, growth and age of the trees

Aims of study: To characterize the wood of Acacia melanoxylon in relation to its potential use in the construction and furniture industry, here we determined the heartwood and sapwood content and distribution within the stem and analyzed their relationship with the growing site, age and growth rate of the trees. Finally, we predicted heartwood content by two easy-to-measure variables.Area of study: Buenos Aires, Argentina.Methods: 20 trees aged between 9 and 32 years were sampled in four sites. Axial sampling was carried out at four heights of the stem (base, breast height, and 30% and 50% of the total height), and the heartwood content (percentage and volume) and sapwood content (cm) determined.Results: The trees analyzed presented conical-shaped heartwood following the outline of the stem along all its commercial height. Within the stem, the highest volume of heartwood was observed at the basal region (53%) and up to 30% of total height, a feature observed in all the sites studied. The sapwood content was constant along the entire stem (2.18 cm). The age of the trees did not influence the heartwood content, whereas the environmental conditions provided by each site (heartwood/volume and heartwood/diameter growth positive ratios) did affect this feature.Research highlights: The absolute amount of heartwood was driven by growth rate, due to the forest structure of non-uniform age. The heartwood volume can be estimated through fitting linear equations (R2 0.78 - 0.89) with two easily measurable variables such as diameter at breast height and tree height.

Models for predicting vertical profiles of heartwood diameter in mature Scots pine

Variation in heartwood diameter (HWD) along the stem was studied in 106 mature Scots pines ( Pinus sylvestris L.) sampled from southern Norway. HWD decreased from the base towards the treetop, following a profile similar to that of the stem diameter (shape of the tree). A few trees deviated from this general pattern. In these trees HWD increased from the base of the stem to a maximum at 2–2.5 m and then decreased towards the top of the tree. Random coefficient mixed models based on a second-degree polynomial of vertical position in the tree and tree variables that can be measured in the forest were developed to predict HWD profiles of pine stems. Seven different models were developed in steps, based on how easily the input variables can be measured. Input variables consisted of information describing the size and shape of trees and information from increment cores. Performances of the models were validated with an independent sample (R2 = 0.88–0.95, root mean square error = 12–19 mm). The high predictive abilities of the models indicate that they can be prospective tools for selecting trees and stem sections within trees to produce logs with HWD suitable for manufacturing of heartwood sawn-wood products.

The Prediction of Heartwood Diameter in Radiata Pine Trees

Cross-sectional characteristics of Pinusradiata trees grown in different parts of Australia were examined. A regression equation which related heartwood diameter at a given age of the tree to the diameter at breast height outside bark and the product of the tree age and its diameter at 5 years gave a high degree of correspondence between observed and predicted heartwood diameter.