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Wood stiffness (modulus of elasticity, MOE) is an important property for conifer wood, with the variability in MOE largely being a function of both the specific gravity (SG) (wood density) and the angle of the microfibrils within the S2 layer of longitudinal tracheids. Rapid analysis techniques can be used together to quantify MOE; while SG can be determined with relative ease, this is not the case for microfibril angle, requiring expensive X-ray diffraction equipment. An alternative to microfibril angle is to measure longitudinal acoustic velocity. The objective of this study was to measure and then model the within tree variation in dynamic MOE (MOEdyn) by developing the methodology to measure ultrasonic velocity (USV) in radial samples from pith to bark using ultrasonic frequencies (>20 kHz). A total of 419 pith-to-bark radial strips, collected from multiple height levels in 92 loblolly pine (Pinus taeda) trees, were processed to obtain matching SG (2mm longitudinal) and USV (8.2-mm longitudinal) samples. Ring-by-ring SG was measured using X-ray densitometry and time-of-flight USV was measured at a 10-mm radial resolution from pith to bark. A subset of samples was sent to SilviScan to determine microfibril angle using X-ray diffraction. The relationship between microfibril angle and USV was strong (R 2 = 0.91, RMSE = 2.6°). Nonlinear mixed-effects models were then developed to predict radial variation in SG, USV and MOEdyn. Fixed effects for the models, which included cambial age and height of disk within tree, had pseudo R 2 values of 0.67 for SG (RMSE = 0.051), 0.71 for USV (RMSE = 316 m/s) and 0.69 for MOEdyn (RMSE = 1.9 GPa). When combined with SG measurements from X-ray densitometry, USV measurements from pith to bark are a powerful tool for assessing variability in wood stiffness. [ABSTRACT FROM AUTHOR]

Near-infrared wavelengths selected by genetic algorithm were used to optimize partial least squares (PLS) regression models for loblolly pine (Pinus taeda L.) from the southeastern United States. Wood properties examined included density (D), microfibril angle, modulus of elasticity and tracheid coarseness (C), radial diameter (R), tangential diameter (T), and wall thickness (w)—measured by SilviScan. The optimization process was run for each property with Agenda 2020 samples utilized for PLS model development and the other sets used for prediction. The number of variables (i.e. wavelengths) varied from 10 to 100 with an optimum number identified by genetic algorithm. When compared to a full data set model (based on 700 wavelengths), calibration and prediction performance of optimized PLS regression models were superior for all properties. Importantly, representative wavelengths for each property were consistently related to recognized bond vibrations observed in specific wood components demonstrating that optimization targets wavelengths directly related to changes in wood chemistry within the examined loblolly pine samples. [ABSTRACT FROM AUTHOR]

Within-tree variation of four handsheet properties (burst index, sheet density, STFI short-span compression strength (STFI) and tensile index) was mapped for loblolly pine trees aged 13 and 22 years using NIR predicted handsheet property data (representing an average of 18 trees for each age). All within-tree maps were similar demonstrating a radial decrease in handsheet properties at all heights, with sheet density and tensile index having the greatest within-tree variation. The corewood zone had the highest values for all properties, while the lowest values were observed in a region consistent with juvenile and transitional outerwood as defined by Burdon et al. (2004). The maps are also similar to, but the inverse of, maps reported in prior studies for density and tracheid coarseness and wall thickness. Relationships amongst the examined handsheet properties and wood and tracheid properties explains the overall similarities of the different maps. The maps provide a representation of within-tree variation of important paper properties at two different ages. An understanding of how these properties vary within loblolly pine trees can aid in better utilization of forest resources. [ABSTRACT FROM AUTHOR]

Loblolly pine is a major fibre source for the pulp and paper industry. Here we developed the first nonlinear models to predict the within-tree and regional variation of tracheid length and width for planted loblolly pine. Data were obtained from macerated tracheids and near-infrared spectroscopy calibration models from trees sampled in 109 stands across the southeastern United States. The fixed effects for the final tracheid length model, which included cambial age, height of disk within tree, and physiographic region, explained 71 percent of the variation with root mean square error (RMSE) of 0.28 mm, while the fixed effects for the final tracheid width model explained 57 percent of the variation with RMSE of 1.4 μm. There was significant variation in tracheid properties across the growing regions. Tree maps showing within-tree variability in tracheid properties were produced. Five simulated scenarios were compared using the models developed, with mean tracheid dimensions calculated on a whole-tree basis at a first and second thinnings, and at final harvest. Also from the final harvest, the tops of trees, and outerwood chips produced during lumber manufacturing were also simulated. For the whole tree scenarios, both mean tracheid length and width increased with age, increasing from 2.24 mm and 40.5 μm (age 12), to 2.51 mm and 41.3 μm (age 18), and to 2.73 and 41.8 μm at age 25, respectively. The tops of the trees at age 25 had a mean tracheid length of 2.46 mm and a mean width of 41.0 μm, while the chips had a mean tracheid length of 3.13 mm and a mean width of 42.5 μm. Due to the models representing samples collected from across the southeastern United States, and their relatively high precision, they are suitable for incorporation into growth and yield systems allowing for prediction of tracheid properties. [ABSTRACT FROM AUTHOR]

Maps developed using Akima's interpolation method, and representing average data for trees aged 13 and 22 years, were used to compare patterns of within-tree variation for Pinus taeda L. (loblolly pine) tracheid properties: coarseness (C), specific surface (S), radial (R) and tangential (T) diameter and wall thickness (w). SilviScan-calibrated near-infrared (NIR) spectroscopy provided data for the analysis with C (Rc2 = 0.85, Rp2 = 0.85), S (Rc2 = 0.83, Rp2 = 0.76), and w (Rc2 = 0.89, Rp2 = 0.93) models having very good calibration / prediction statistics, while those for T and R diameter were moderate (Rc2 = 0.79, Rp2 = 0.57) and poor (Rc2 = 0.64, Rp2 = 0.19), respectively. C, S, and w maps were similar to the density maps for P. taeda and indicate the properties increase radially at all heights. The T diameter map was similar to maps reported for microfibril angle except that T diameter increased radially and with height whereas microfibril angle decreased radially and with height. The map for R diameter increased with height and was unlike the other properties examined; caution is recommended regarding any interpretations based on the R diameter map owing to the weak statistics observed for the NIR model. Changes observed between the two ages are consistent with the asymptotic progression of properties associated with maturation. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) spectra or NIR-hyperspectral images obtained from radial strips or wood discs provide a cost-effective methodology for examining wood property variation within trees. The calibration used for wood property prediction is critical and can be obtained using two fundamentally different approaches. One involves using a spatial-specific model where wood property data and corresponding spectral data are measured at the same resolution for calibration and prediction, e.g. 10-mm radial increments. The other provides a spatial-interpolated model and involves measuring a property on a broad-scale, e.g. whole-tree, calibrating this data against NIR spectra representing the equivalent scale and then using the calibration to predict the property at higher resolution. To understand the impact of these approaches on subsequent patterns of within-tree variation, whole-tree air-dry density (ADD) and coarseness maps, based on data obtained using the two different approaches, were compared. Patterns of ADD and coarseness variation were comparable indicating that both approaches can be utilized to examine within-tree variation. Spatial-interpolated models have a distinct advantage; being based on whole-tree (or disc) samples, they greatly reduce the cost of wood property analysis and allow the development of maps for properties that are costly and difficult to measure, for example, pulp yield. [ABSTRACT FROM AUTHOR]

This study developed regional calibration models for the prediction of loblolly pine (Pinus taeda) tracheid properties using near-infrared (NIR) spectroscopy. A total of 1842 pith-to-bark radial strips, aged 19–31 years, were acquired from 268 trees from 109 stands across the southeastern USA. Diffuse reflectance NIR spectra were collected at 10-mm increments from the radial face of pith-to-bark strips using a FOSS 5000 scanning spectrometer. A subset of the 10-mm samples was selected based on the NIR spectra uniqueness and placed in calibration (N = 1020) and validation (N = 998) test sets. The samples were macerated and the tracheid properties measured using an optical analyzer (Techpap MorFi Fiber and Shive Analyzer). Models were created using partial least squares (PLS) regression using the calibration samples, and their performance checked using the validation set. Prediction PLS models for tracheid length were strong when checked with the validation set [Rp2 = 0.87, standard error of prediction (SEP) = 0.23 mm, ratio of performance to deviation (RPD) = 2.8]. Prediction models for tracheid width had moderate fit statistics (R2 = 0.61, SEP = 1.6 μm, RPD = 1.6), but the SEP was similar to the measurement error of the camera (± 2 μm). The NIR wavelengths of importance were largely attributed to cellulose. The 1542 nm wavelength explained 77% of the variation in tracheid length (RMSE = 0.31 mm). These results demonstrate that NIR spectroscopy models for tracheid length and width can be developed from a diverse set of samples and still maintain prediction accuracy. [ABSTRACT FROM AUTHOR]

Time-domain reflectometry (TDR) can be used to predict the moisture content in porous materials, including soil, and is an exciting tool that could be used to measure the moisture content in wet-stored wood. Three-rod probes with 127 mm- or 152 mm-long rods were inserted into 62 loblolly pine and 34 sweetgum saturated bolts. The bolts were air dried over a span of five weeks. TDR waveforms and moisture content were periodically recorded. In total, 534 and 482 readings were taken for the loblolly pine and sweetgum bolts, respectively. An algorithm in R was written to automatically analyze the apparent length of the TDR rods. Calibration models were developed between moisture content and X (apparent length/actual rod length). A three-parameter logistic model was developed for loblolly pine (R2=0.64) and sweetgum (R²=0.84). The process was repeated using shorter bolts and 152 mm-long rods, resulting in improved models for loblolly pine (R²=0.99) and sweetgum (R²=0.97). Overall, TDR and the algorithm written to analyze the waveforms were accurate in predicting moisture content and could be used to monitor moisture in wet-decks. [ABSTRACT FROM AUTHOR]

A study was conducted to identify geographical variation in loblolly pine bark and wood properties at the whole-tree level and to quantify the responses in whole-tree bark and wood properties following contrasting silvicultural practices that included planting density, weed control, and fertilization. Trees were destructively sampled from both conventionally managed stands and various designed experimental trials established across the southern United States by various research cooperatives and forest product industries to quantify the bark and wood properties of loblolly pine. Bark (percentage bark, specific gravity [SG], and moisture content [MC]) and wood (SG, MC, green weight of wood/m3, and green weight of wood and bark/m3 of volume) properties were measured from disks collected at multiple heights from sampled trees and used to compute the whole-tree bark and wood properties. Significant regional variation was observed for whole-tree bark and wood properties. Bark and wood SG showed an increasing trend from inland to coastal regions and vice versa for bark and wood MC. The effect of different silvicultural treatments on bark and wood properties were generally absent; but a significant effect on bark percentage, MC, and green weight of wood and bark/m3 was observed for trees that received intensive treatments such as early age competition control plus multiple fertilizations. [ABSTRACT FROM AUTHOR]

The use of clonal varieties in forestry offers great potential to improve growth traits (quantity) and wood properties (quality) of loblolly pine ( Pinus taeda L.). Loblolly pine trees established via somatic embryogenesis (clones), full-sib zygotic crosses, and half-sib zygotic open-pollinated families were sampled to identify variation in growth and wood properties among and within clonal lines and zygotic controls. Increment cores 5 mm in diameter were collected at age 4 from a total of 2615 trees. Growth properties (diameter at 1.4 m and total tree height) and wood properties (whole-core density, latewood and earlywood density, and latewood percent) were measured for each tree sampled in the study. Overall, growth properties were better for full-sib seedling than for clonal lines, whereas wood density was higher for clonal lines than full-sib and open-pollinated seedlings. However, there were clonal lines with better growth and higher wood density. Clonal repeatability of both growth and wood properties across sampled sites and genetic correlations between growth and wood traits were determined, with higher repeatability observed for wood traits compared with growth traits. Significant genetic correlations were observed for tree height and wood properties, whereas weak correlations were observed for diameter and wood properties. [ABSTRACT FROM AUTHOR]

Conventionally, increment cores collected at breast height (1.4 m) have been used to measure wood properties of standing loblolly pine ( Pinus taeda L.) trees. This height has been used because of the ease of sampling and cost involved in extracting the cores. In this study, the efficacy of a breast-height core to represent whole-tree specific gravity (SG) and moisture content (MC) was examined. The sampling height that best represents whole-tree SG and MC was identified using the correlation between volume-weighted whole-tree SG and MC with SG and MC measurements collected at different heights within a tree. We found a high correlation between observed whole-disk SG and MC with volume-weighted whole-tree SG and MC at most sampling heights. The strength of the correlation followed a skewed parabolic curve form for both wood properties. The strongest correlations were observed between 4.6 and 6.1 m, with marginally lower correlations at the base of the tree, and the weakest correlations were observed towards the tip of the tree. In addition, it was found that the number of stands and trees that need to be sampled to achieve a certain accuracy in overall mean whole-tree SG and MC was greater if breast height was used as a sampling height compared with the most representative sampling heights identified (4.6 m for SG and 6.1 m for MC). [ABSTRACT FROM AUTHOR]

Results are presented on the relationships among loblolly pine tree age and wood characteristics and the properties of pulp obtained when the trees were chipped and pulped. We selected 13-year-old and 22-year-old loblolly pine trees (18 of each) to represent specified ranges of specific gravity and lignin content. The trees were further characterized by chemical analysis, near infrared (NIR) spectroscopy, and SilviScan analysis of fiber dimensions and properties before being pulped by the kraft process. Handsheets formed from the resulting pulps were characterized in terms of sheet properties that are important for linerboard grades. Multiple regression analysis was then used to identify wood characteristics that most influenced sheet properties and to derive equations relating sheet properties to tree age, specific gravity, and chemical composition. We also developed calibrations so that sheet properties could be predicted from NIR spectroscopic analysts of wood. Nearly all differences in properties of pulps made from 13- and 22-year-old trees were attributable to differences in fundamental wood properties. Sheet properties could be estimated by measuring their near NIR spectra. [ABSTRACT FROM AUTHOR]

Abstract: Early age competition control has been reported to significantly improve the growth and yield of plantation grown loblolly pine. The objective of this paper is to understand the changes in wood properties: basal area weighted whole disk SG, earlywood SG (EWSG), latewood SG (LWSG) and latewood percent (LWP) of 14year-old trees which received early age herbaceous and hardwood competition control, using data collected from 13-sites across 4-physiographic regions in the southeastern USA. The study was laid out in a randomized complete block design and had four levels of weed control (no weed control; woody vegetation control; herbaceous vegetation control; and woody and herbaceous vegetation control), with four blocks at each site. Increment cores 12mm in diameter were collected at breast height (1.37m) from 9-trees in each plot and ring-by-ring SG, EWSG, LWSG and LWP measured using a X-ray densitometer. Whole disk basal area weighted SG and LWP were determined for each tree and used for analysis. A reduction in whole disk SG of 0.039 and 0.0014 and LWP of 7.38% and 3.62% was observed for trees which received total weed control compared to no weed control, for lower and upper Coastal Plain sites, respectively. For trees receiving total weed control compared to no weed control, it was observed that the diameter of the juvenile core increased by 20% on average across all physiographic regions. However, no change in the length of the juvenile period was observed among treatments other than the regional differences. [Copyright &y& Elsevier]

Growth and wood properties were measured on breast height cores collected from two stands, New Bern and Bertie, located in the lower Coastal Plain of North Carolina. The New Bern site was thinned before fertilizer application, and the Bertie site was not. The study was laid out in a randomized complete block design with each treatment replicated in four blocks at New Bern and two blocks at Bertie. The treatments were different levels of nitrogen fertilization: control (no nitrogen) and 112, 224, and 336 kg/ha. In addition, 28 kg/ha of phosphorus was included with each treatment. The objective of this study was to examine the response in growth and wood properties to midrotation fertilization in a thinned versus an unthinned stand. A significant decrease in latewood specific gravity was observed following nitrogen fertilization in the thinned stand but not in the unthinned stand. Whole ring width, latewood width, and earlywood width significantly increased following nitrogen fertilization at New Bern but not at Bertie. Whole ring specific gravity, earlywood specific gravity, latewood percentage, and earlywood:latewood ratio did not show any change due to fertilization in either stand. Responses in both growth and wood characteristics lasted for 2-3 years following fertilization and depended on the amount of fertilizer applied and whether or not the site was thinned. The response to nitrogen application was significant for the thinned stand only. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Near infrared diffuse reflectance spectra collected in 10-mm sections were used for the estimation of air-dry density (AD), microfibril angle (MFA), stiffness (MOE), tracheid coarseness (COARS), and tracheid wall thickness (WTHICK) in wood radial strip samples obtained at breast height (1.4 m) from 60 Pinus taeda trees. Calibration models were developed using traditional partial least squares (PLS) and kernel regression. The kernel methods included radial basis functions-partial least squares (RBF-PLS) and least-squares support vector machines (LS-SVM). RBF-PLS and LS-SVM models outperformed PLS-CV calibrations in terms of fit statistics. MFA and MOE, two properties that exhibited nonlinearity, showed the most significant improvements compared to PLS. In terms of predictive ability RBF-PLS performed better than PLS for the prediction of MFA, MOE, and COARS. LS-SVM showed better prediction statistics in all cases, except for WTHICK that gave similar statistics compared to PLS and was superior to RBF-PLS. By adding statistically significant factors to the PLS regressions, it was possible to capture some of the nonlinear features of the data and improve the predictive ability of the PLS models. [ABSTRACT FROM AUTHOR]

Abstract: Wood quality attributes were examined in six stands of slash pine (Pinus elliottii Engelm. var. elliottii) and loblolly pine (P. taeda L.) in the lower Coastal Plain of Georgia and Florida. Several plots comprised each stand, and each plot was divided so that it received three fertilizer treatments: a control treatment with herbaceous weed control at planting and brush control at mid-rotation only (control); 45kgha−1 N+56kgha−1 P+herbaceous weed control at planting and 224kgha−1 N+45kgha−1 P+brush control at mid-rotation (fertilizer with N at planting); and 56kgha−1 P+herbaceous weed control at planting and 224kgha−1 N+45kgha−1 P+brush control at mid-rotation (fertilizer without N at planting). Ring width, ring earlywood specific gravity (SG), ring latewood SG, whole ring SG, and ring percent latewood were measured on each of seven trees. Of these measurements, this study focused mainly on the properties related to SG. Examination of the rings showed that latewood SG was significantly lower in trees treated with fertilizers with and without N at planting in the two to three years following fertilization, but that latewood SG gradually returned to a level similar to the control. Fertilizer without N at planting may also have had a brief negative effect on earlywood SG following mid-rotation fertilization, but it was not as clear or lasting as the effect on latewood SG. Additionally, although slash and loblolly pine appear to differ in the developmental patterns of these SG properties, there were no significant differences in how these patterns interacted with treatment. This study demonstrated that fertilization treatments have similar short-term effects on the SG of slash and loblolly pines, particularly in latewood, but the trees will return to a SG pattern consistent with unfertilized trees within two or three years. [Copyright &y& Elsevier]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Data from a variability study of loblolly pine (Pinus taeda L.) based on weighted core specific gravity (WCSG) were examined to show how costs and variance estimates are used in designing efficient sampling strategies. Increment cores for the determination of WCSG were taken from 3957 trees across six distinct physiographic regions in the southeastern United States. More variability was found to exist among stands than within stands. This indicates that reducing the variation of the mean of WCSG can be accomplished by sampling more stands and fewer trees in the region of interest. The number of stands and trees to sample is dictated by the maximum allowable cost and the precision required of the sample mean, and formulas are given for such calculations. The estimate of among-stand variability was found to be similar among the regions of interest, whereas larger within-stand variation was found to exist in the South Atlantic and Hilly regions. The standard error of the mean was found to increase with an increase in the age at which the stand was sampled. When sampling across multiple stands (at any age), little if any gain in the precision of the standard error of the mean is gained by sampling more than 15 trees. In the general case where one is interested only in the value of WCSG in one stand and precision or cost–time factors are not of consideration, it would suffice to sample between 45 and 55 trees at any age. [ABSTRACT FROM AUTHOR]

• Only stand density kept below 297 TPH from age 7 reduced MOE, MOR, and specific gravity. • As planting density declined the age of transition corewood to outerwood decreased. • Specific gravity was similar among planting densities at a well-drained site. • Outerwood transition occurred earlier for a relocated Coastal Plain genotype. • A relocated Coastal Plain genotype had higher latewood proportion. Changes in ownership and forest product use patterns have incentivized growing loblolly pine (Pinus taeda L.) for chip-and-saw and sawtimber in shorter rotations in the southeastern United States. These management objectives can be accomplished by relatively low stand densities and moving fast-growing genotypes from the Atlantic Coastal Plain to other regions of the loblolly pine range, but wood quality concerns accompany these silvicultural options. In three trials in the Western Gulf region of the mid-South United States, effects of stand density management options on key wood properties (specific gravity, corewood (juvenile wood) diameter, corewood proportion, latewood proportion, corewood:outerwood (juvenile wood:mature wood) transition age as determined using specific gravity) were tested. At one site, clearwood modulus of elasticity (MOE) and modulus of rupture (MOR) were measured. Genotypes of Atlantic Coastal Plain and Western Gulf origin were also tested at two sites. In a trial in which stand density was managed at diverse levels through sequential thinning, beginning at precommercial size, only a regime that was commercially thinned to half its density two times from 297 TPH at age 7 to 62 TPH by age 41 had significant reductions in MOE, MOR, and specific gravity. Corewood diameter increased with decreasing planting density at two sites at the northwestern edge of the loblolly pine range, but corewood proportion declined with decreasing planting density due to greater diameter growth and earlier transition from corewood to outerwood. Specific gravity differences among planting densities was site-specific, with no differences at the more well-drained site. Latewood proportion, which was greater at higher planting densities, was more strongly correlated with specific gravity differences among planting densities. A planting density between 1075 and 1680 TPH would likely be optimum for these site conditions for balancing tree volume growth with minimizing reductions in specific gravity associated with reduced latewood proportion and larger corewood size. The Atlantic Coastal Plain genotype retained its tendencies to transition to outerwood earlier and have greater latewood proportions relative to a local genotype when planted at these Western Gulf sites, and its specific gravity was similar to that of the local genotype. Together these trials suggest that forest managers have flexibility in managing loblolly pine stand density without altering wood properties. Furthermore, these results provide some evidence that moving genotypes may not carry a risk of reduced wood specific gravity. [ABSTRACT FROM AUTHOR]

Loblolly pine (Pinus taeda L.) is one of the most important commercial timber species in the world. While the species is native to the southeastern United States of America (USA), it has been widely planted in southern Brazil, where it is the most commonly planted exotic species. Interest exists in utilizing nondestructive testing methods for wood property assessment to aid in improving the wood quality of Brazilian grown loblolly pine. We used near-infrared hyperspectral imaging (NIR-HSI) on increment cores to provide data representative of the radial variation of families sampled from a 10-year-old progeny test located in Rio Negrinho municipality, Santa Catarina, Brazil. Hyperspectral images were averaged to provide an individual NIR spectrum per tree for cluster analysis (hierarchical complete linkage with square Euclidean distance) to identify trees with similar wood properties. Four clusters (0, 1, 2, 3) were identified, and based on SilviScan data for air-dry density, microfibril angle (MFA), and stiffness, clusters differed in average wood properties. Average ring data demonstrated that trees in Cluster 0 had the highest average ring densities, and those in Cluster 3 the lowest. Cluster 3 trees also had the lowest ring MFAs. NIR-HSI provides a rapid approach for collecting wood property data and, when coupled with cluster analysis, potentially, allows screening for desirable wood properties amongst families in tree improvement programs. [ABSTRACT FROM AUTHOR]

With conifer plantations having an increasingly important role in meeting the fiber needs of society, an understanding of the effect of silvicultural practices on wood quality is critical. The perception of wood quality varies, making it hard to define in a single statement; however, possibly the most succinct definition is “a measure of the aptness of wood for a given use”. In general, properties that have a positive influence on a specific product assist in defining changes in wood quality. Since wood properties exhibit large variability within annual rings, within trees, and among trees in a stand, and have both genetic and environmental components (i.e., vary with different physiographical regions), it is imperative to have an understanding of wood properties at multiple levels. In this paper, we review the typical variation patterns in wood properties of conifers, with specific emphasis on loblolly pine (Pinus taeda L.), and radiata pine (Pinus radiata D.Don), two of the most common conifer plantation species globally. We also describe the impact of conventional silvicultural treatments on wood quality. Modeling efforts to predict variation in wood properties within trees, and in response to silvicultural treatments are also summarized. [ABSTRACT FROM AUTHOR]

Maps developed using Akima’s interpolation method were used to compare patterns of within-tree variation for Pinus taeda L. (loblolly pine) wood properties in plantation-grown trees aged 13 and 22 years. Air-dry density, microfibril angle (MFA) and modulus of elasticity (MOE) maps represented the average of 18 sampled trees in each age class. Near infrared (NIR) spectroscopy models calibrated using SilviScan provided data for the analysis. Zones of high density, low MFA and high MOE wood increased markedly in size in maps of the older trees. The proportion of wood meeting the visually graded No. 1 (11 GPa) and No. 2 (9.7 GPa) MOE design values for southern pine lumber increased from 44 to 74% and from 58 to 83% respectively demonstrating the impact of age on end-product quality. Air-dry density increased from pith to bark at all heights but lacked a significant trend vertically, while radial and longitudinal trends were observed for MFA and MOE. Changes were consistent with the asymptotic progression of properties associated with full maturity in older trees. [ABSTRACT FROM AUTHOR]