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The space-time structure of a teak wood specific gravity (SG) dataset was analyzed using a mixed-effects model. Spatial correlation increased in space, a phenomenon attributable to the maturation of apical meristems, while the temporal correlation of vascular meristems decreased over time. The decay of temporal correlation over time was attributed to the diminishing crown effect on the later formed wood further away from the pith, morphogen gradient, and probably changing microenvironmental conditions. The Kronecker product was used to collect spatiotemporal data on the intricate dynamic process of the evolution of the apical and lateral meristems. The results showed that height and relative radial distance (RRD) (i.e., the flow of time with wood formation) were statistically significant factors, with their interaction showing no significance. The results confirm the usefulness of using the space-time approach to elucidate the interaction between the apical and lateral meristems, two major inherent biological systems that control tree growth and wood formation dynamics. To understand the origins of patterns that vary both temporally and spatially in the tree, future work should describe the variation of SG within the tree due to increasing height (space) and diameter (age) as a matrix; then the correlation function can be modelled.

Abstract To test whether radial variation of wood specific gravity (WSG) is controlled by tree age or tree size in teak (Tectona grandis L.f) plantation trees, opposing different-length pith-to-bark strips which represents the differential lateral growth rate was compared using mixed-effects model which considers the heterogeneity of variances and dependency in the data to gain insight into the stochastic processes that govern the wood formation process. Various models were tested in devising an appropriate radial WSG model. Models that accounted for serial correlation in WSG data performed better than the simple structure that assumes zero correlation between measurements. The autoregressive plus random tree effect structure performed better in describing the radial variation pattern. The variability of the data related to random fluctuations during tree development and the wood formation process is modeled by the autoregressive parameter revealing the intrinsic complexity of wood formation. Since they cannot be attributed to observed factors, models should consider temporal or serial correlations when assessing wood quality. The results revealed that tree age is a decisive factor in controlling the WSG of wood, while tree size is statistically less important. Furthermore, the core wood production period varies with the growth rate. It is shown that the core wood area decreased with slow growth. Findings presented here appear to provide the first demonstration of radial variation in WSG with respect to growth rate and age for planted teak growing in Ghana.

Heartwood color is a complex trait that affects the economic and aesthetic value of the wood but is highly variable. How the color of the heartwood varies spatially and temporally is poorly understood. To illustrate how heartwood color varies within a tree, two opposite aspects of wood within the same tree, representing differential growth rate, were used to model the long-short axis system jointly. The color of the heartwood on the long and the short axis was considered to be two different traits. By jointly modeling the long and short axes, the correlation was examined between aspect (spatial) and contemporaneous correlations (within aspect). Spatial and temporal correlations and their interactions describe the indirect physiological, genetic, and environmental changes in wood formation with time and position in the trunk. Spatial correlations were consistently lower than temporal correlations but were positive and significant. Between the heartwood color parameters, b* showed a relatively higher spatial correlation. The results suggest that there is a spatial correlation in the long-short axis for all color parameters and in the two surfaces. Variations between aspects were not statistically significant for any color parameter. The bivariate mixed model method revealed hidden physics behind heartwood color formation. Models need to be developed to account for both spatial and temporal dependence in studies of wood property change.

Changes in the physical and mechanical properties and anatomical structures of spruce (Picea) and larch (Larix) specimens before and after fire-retardant impregnation were studied. Results indicated that the static modulus of elasticity (MOE), dynamic modulus of elasticity (DMOE), and the Brinell hardness of the specimens decreased for both wood species upon post-treatment. This could be accounted for by the degradation of hemicelluloses by the phosphorus-based compound, the minute cracks in the latewood cell wall, and the enlarged width of the cell lumen of the specimen resulting from the vacuum-pressure treatment. However, the decreased ratio of the MOR and DMOE to density contributed to lower sound transmission, which is expected to be important in a housing environment.

Information on the weathering behaviour of Cunninghamia lanceolata (Lamb.) Hook. is needed to provide references for wood weatherproof pre-treatment and to improve wood utilization. Therefore, this study was conducted to understand the variation in the intrinsic weathering behaviour of Cunninghamia lanceolata (Chinese fir) under natural conditions. Wood samples from 15 Cunninghamia lanceolata trees aged 26–30 years old were used. The structural degradation and discoloration of wood surfaces before and after exposure were compared. The results show that the weathering behaviour of wood was weakened from heartwood to sapwood and enhanced from the bottom to the top. This study provided information for weatherability research and improved wood utilization of Cunninghamia lanceolata.

To quickly clarify the effect of heat treatment on weatherability of Cunninghamia lanceolate (Lamb.) Hook., we investigated the surface degradation under natural exposure. A comparison between heat-treated and untreated samples was taken based on surface color changes and structural decay at each interval. Over four weeks of natural exposure, multiple measurements were carried out. Results show that color change decreased in the order of 220 °C heat-treated > untreated > 190 °C heat-treated. The results also indicate that the wood surface color stability was improved via the proper temperature of thermal modification. Low vacuum scanning electron microscopy (LVSEM) results expressed that thermal modification itself had caused shrinking in the wood surface structure. From the beginning of the weathering process, the heat treatment affected the surface structural stability. After natural exposure, the degree of wood structure decay followed the pattern 220 °C heat-treated > 190 °C heat-treated > untreated. Therefore, when considering the impact on the structure, thermal modification treatment as a protective measure to prevent weathering was not an ideal approach and requires further improvement.

Tree breeders face the problem of negative correlations between wood properties and growth traits. It is necessary to overcome this difficulty in order to obtain promising genotypes. The selection index is one of the helpful tools in this process, because it allows multiple features of interest to be selected. In this study, a multiple trait selection index for Khasi pine (Pinus kesiya Royle ex Gordon) grown in Malawi was developed. Data on wood properties and growth traits were collected from six families of P. kesiya at the age of 30 years. The breeding objective was defined in terms of wood stiffness, wood strength and volume. Selection traits included in the index were wood stiffness (MoE), wood strength (MoR), volume (Vol.), wood density (WD), and diameter at breast height (DBH). The index was termed as I T = − 80.36 M o E − 14.60 M o R + 132.07 V o l . + 4858.09 W D − 7.56 D B H . The accuracy of the index was 98.8% and the correlation between the index and the aggregate breeding objective was 0.994. A genetic gain of 16.7% for volume, 14.8% for wood stiffness and 13.2% for wood strength would be expected from a standardized 10% selection intensity. Therefore, application of the developed selection index is necessary in order to increase the efficiency of the Pinus kesiya breeding programme in Malawi.

Accurate prediction of genetic potential and response to selection in breeding requires knowledge of genetic parameters for important selection traits. In this study, we estimated genetic parameters for wood properties in Khasi pine (Pinus kesiya Royle ex Gordon) grown in Malawi. Data on wood properties and growth traits were collected from six families of Pinus kesiya at the age of 30. The results show that wood density had a higher genetic control (h2 = 0.595 ± 0.055) than wood stiffness (h2 = 0.559 ± 0.038) and wood strength (h2 = 0.542 ± 0.091). The genetic correlation among wood quality traits was significantly moderate (0.464 ± 0.061) to high (0.735 ± 0.025). The predicted genetic response indicated that selection for wood density at 10% selection intensity would increase stiffness and strength by 12.6% and 8.85%, respectively. The genetic correlations between growth and wood quality traits were moderately unfavourable. However, sufficient variation exists within the breeding population to select individuals with both good growth rate and high wood quality traits. It is therefore suggested that all trees with both diameter at breast height (DBH) greater than 32.0 cm and density greater than 0.593 g/cm3 must be selected in order to increase the efficiency of the breeding programme. However, in the long term, it is recommended that the best selection strategy would be to develop a multiple-trait selection index. The selection index should be developed using optimal index weights for the advanced Pinus kesiya breeding programme in Malawi.

Successful development of an appropriate tree breeding strategy and wood utilization requires information on wood properties. This study was therefore conducted to assess wood density and mechanical properties of Pinus kesiya Royle ex Gordon grown in Malawi. Wood samples from six families of P. kesiya at the age of 30 years were used for the study. The estimated mean wood density, Modulus of Elasticity (MoE), Modulus of Rupture (MoR) and moisture content were 0.593 ± 0.001 g/cm3, 13.46 ± 0.07 GPa, 113.67 ± 0.57 MPa and 12.08% ± 0.03%, respectively. There were statistically significant (p < 0.001) differences in wood density and mechanical properties along the radial direction and stem height. Wood density and mechanical properties increased from pith to bark and decreased from the butt upwards. There were no significant (p > 0.05) differences in wood density and mechanical properties among the families. This is an indication that any tree among the families can be selected for tree improvement programs if density is considered as a variable. Wood density had a strong positive significant linear relationship with both MoE (r = 0.790; p < 0.001) and MoR (r = 0.793; p < 0.001). This suggests that it has the potential to simultaneously improve the wood density and mechanical properties of this species. Therefore, controlling wood density for the tree improvement program of P. kesiya in Malawi would have a positive impact on mechanical properties.

The space-time structure of a teak wood specific gravity (SG) dataset was analyzed using a mixed-effects model. Spatial correlation increased in space, a phenomenon attributable to the maturation of apical meristems, while the temporal correlation of vascular meristems decreased over time. The decay of temporal correlation over time was attributed to the diminishing crown effect on the later formed wood further away from the pith, morphogen gradient, and probably changing microenvironmental conditions. The Kronecker product was used to collect spatiotemporal data on the intricate dynamic process of the evolution of the apical and lateral meristems. The results showed that height and relative radial distance (RRD) (i.e., the flow of time with wood formation) were statistically significant factors, with their interaction showing no significance. The results confirm the usefulness of using the space-time approach to elucidate the interaction between the apical and lateral meristems, two major inherent biological systems that control tree growth and wood formation dynamics. To understand the origins of patterns that vary both temporally and spatially in the tree, future work should describe the variation of SG within the tree due to increasing height (space) and diameter (age) as a matrix; then the correlation function can be modelled. [ABSTRACT FROM AUTHOR]

The ultrasonic wave velocities in wood impregnated with a fire-retardant chemical were measured via a non-contact method. An air-coupled ultrasonic wave was made to propagate along the radial direction of the wood. The wave velocities in the wood samples after chemical impregnation were larger than those before impregnation. With increased chemical concentration, the relative changes in the velocities increased to a maximum of 16.3%, and these velocity changes exhibited a strong correlation with the chemical retention. These findings suggest that it is possible to evaluate the uniformity distributions of chemicals in fireretardant- treated wood via a non-contact and nondestructive method based on air-coupled ultrasonics. [ABSTRACT FROM AUTHOR]

Tree breeders face the problem of negative correlations between wood properties and growth traits. It is necessary to overcome this difficulty in order to obtain promising genotypes. The selection index is one of the helpful tools in this process, because it allows multiple features of interest to be selected. In this study, a multiple trait selection index for Khasi pine (Pinus kesiya Royle ex Gordon) grown in Malawi was developed. Data on wood properties and growth traits were collected from six families of P. kesiya at the age of 30 years. The breeding objective was defined in terms of wood stiffness, wood strength and volume. Selection traits included in the index were wood stiffness (MoE), wood strength (MoR), volume (Vol.), wood density (WD), and diameter at breast height (DBH). The index was termed as IT = -80.36 MoE - 14.60 MoR + 132.07 Vol. + 4858.09 WD - 7.56 DBH. The accuracy of the index was 98.8% and the correlation between the index and the aggregate breeding objective was 0.994. A genetic gain of 16.7% for volume, 14.8% for wood stiffness and 13.2% for wood strength would be expected from a standardized 10% selection intensity. Therefore, application of the developed selection index is necessary in order to increase the efficiency of the Pinus kesiya breeding programme in Malawi. [ABSTRACT FROM AUTHOR]

Successful development of an appropriate tree breeding strategy and wood utilization requires information on wood properties. This study was therefore conducted to assess wood density and mechanical properties of Pinus kesiya Royle ex Gordon grown in Malawi. Wood samples from six families of P. kesiya at the age of 30 years were used for the study. The estimated mean wood density, Modulus of Elasticity (MoE), Modulus of Rupture (MoR) and moisture content were 0.593 ± 0.001 g/cm3, 13.46 ± 0.07 GPa, 113.67 ± 0.57 MPa and 12.08% ± 0.03%, respectively. There were statistically significant (p < 0.001) differences in wood density and mechanical properties along the radial direction and stem height. Wood density and mechanical properties increased from pith to bark and decreased from the butt upwards. There were no significant (p > 0.05) differences in wood density and mechanical properties among the families. This is an indication that any tree among the families can be selected for tree improvement programs if density is considered as a variable. Wood density had a strong positive significant linear relationship with both MoE (r = 0.790; p < 0.001) and MoR (r = 0.793; p < 0.001). This suggests that it has the potential to simultaneously improve the wood density and mechanical properties of this species. Therefore, controlling wood density for the tree improvement program of P. kesiya in Malawi would have a positive impact on mechanical properties. [ABSTRACT FROM AUTHOR]