Latewood Proportion Research Articles

Predicting wood and tracheid properties of Scots pine

Models were developed for predicting the proportion of latewood, wood density, tracheid length, tracheid width, and the ratio of cell wall thickness to tracheid width in individual annual rings of Scots pine (Pinus sylvestris L.). The models needed to be applicable as a part of a stand growth simulation system, which is based on growth models at the tree level. Data were collected from long-term thinning, thinning-fertilisation, and precommercial thinning experiments on mineral soil and drained peatland in southern and central Finland. The wood and tracheid properties were related to radial increment rate and distance from the pith outwards. An increased increment rate, caused by the different treatments and environmental conditions, resulted in similar types of changes in the wood and tracheid properties irrespective of the factors promoting radial increment. Although most of the average values of the properties were predicted unbiased, there were large random variations between individual trees and annual rings. The fixed parts of the models accounted for the following percentages of the variation: latewood proportion, 42%, wood density, 35%, tracheid length, 84%, tracheid width, 44%, and cell wall percentage, 29%. Incorporating the models for wood and tracheid properties into forest management planning systems enables estimates for the conversion of different silvicultural regimes into internal stem structure and wood quality.

Adaptability to climate change in forestry species: drought effects on growth and wood anatomy of ponderosa pines growing at different competition levels

More stressful conditions are expected due to climatic change in several regions, including Patagonia, South-America. In this region, there are no studies about the impact of severe drought events on growth and wood characteristics of the most planted forestry species, Pinus ponderosa (Doug. ex-Laws). The objective of this study was to quantify the effect of a severe drought event on annual stem growth and functional wood anatomy of pines growing at different plantation densities aiming to understand how management practices can help to increase their adaptability to climate change. Growth magnitude and period, specific hydraulic conductivity, and anatomical traits (early- and latewood proportion, lumen diameter, cell-wall thickness, tracheid length and bordered pit dimensions) were measured in the ring 2008-2009, which was formed during drought conditions. This drought event decreased annual stem growth by 30-38% and 58-65% respect to previous mean growth, in open vs. closed stand trees, respectively, indicating a higher sensitivity of the latter, which is opposite to reports from the same species growing in managed native forests in USA. Some wood anatomical variables did differ in more water stressed trees (lower cell wall thickness of early wood cells and higher proportion of small-lumen cells in latewood), which in turn did not affect wood function (hydraulic conductivity and resistance to implosion). Other anatomical variables (tracheid length, pit dimensions, early- and latewood proportion, lumen diameter of early wood cells) did not differ between tree sizes and plantation density. The results suggest that severe drought affects differentially the amount but not the function and quality of formed wood in ponderosa pine growing at different competition levels.

Variations in the radial growth and wood density components in relation to cambial age in 30-year-old Pinus brutia Ten. at two test sites

Radial growth and wood density are important traits in assessing wood quality. Our objective was to investigate patterns of variation of radial growth (ring width, earlywood width, latewood width, latewood proportion) and wood density (ring average density, earlywood density, latewood density) components in a 30-year-old Pinus brutia at two test sites in Turkey. Wood increment cores at a height of 1.30 cm (dbh) from 1,010 trees at age 30 years were evaluated at two test sites. The radial growth and wood density traits of the individual rings were measured using X-ray densitometry. The test sites showed statistically significant differences in the radial growth traits but not in the wood density traits, suggesting that the wood density traits are less subject to environmental changes. The ring average density was relatively low (485 kg/m3) at early cambial ages (near the pith) and increased to 501 kg/m3 at later cambial ages (near the bark). The latewood density was 550 kg/m3 near the pith, increased steadily to 630 kg/m3 at cambial age 12, and remained stable thereafter. In contrast, the earlywood density and latewood proportion were highest near the pith. The twelfth ring from the pith appeared to represent the transition from juvenile to mature wood. The unique relationships among early and latewood densities and latewood proportion in the juvenile and mature wood contribute to more uniform wood both within a given annual ring and between the juvenile and mature portions of the stem in P. brutia. Thinning increased the ring width, latewood proportion, and ring average density.

Tracheid length – growth relationships of young Pinus brutia grown on reforestation sites

Brutia pine (Pinus brutia Ten.) reforestations have been successfully used for decades in restoration of degraded forest ecosystems in Greece. The future purpose of these reforestations might expand to include wood utilisation. This study provides information on tracheid length of juvenile brutia pine aged 14–22 years grown on good and medium sites in Northeastern Greece. In addition, relationships among ring width, latewood proportion, wood density, and tracheid length were evaluated by using Causal Correlation Analysis. Similar mean tracheid length values were found for good and medium sites. Radial variability of tracheid length was similar on the good and medium sites, showing the typical increase in the juvenile phase. On both site types, latewood proportion showed a strong and positive relationship with wood density. Unexpectedly and only on the good sites, a significant positive relationship was found between ring width and wood density. On the medium sites, tracheid length was negatively related to fast growth and positively to high wood density. Tracheid length on the good sites was correlated only with latewood proportion with a weak positive relationship. The overall results may provide opportunities to better understand the quality of small-dimension timber of brutia pine and to better utilise it.

A Comparison of earlywood–latewood Demarcation Methods – A case study in Loblolly PINE

Demarcating the transition from earlywood (EW) to latewood (LW) is important for accurately estimating the width of both wood types within an annual ring, their respective densities and the proportion of LW within an annual ring. Different methods have been used to define the transition from EW to LW and include Mork’s index, the threshold density method and the inflection point method. In loblolly pine (Pinus taeda L.) a threshold value of 480 kg/m3 (basic density) has conventionally been used to demarcate EW from LW. In this study the three methods: a threshold density of 480 kg/m3, the inflection point method and Mork’s index were used to define the point at which EW transitioned to LW using annual rings for 20 loblolly pine breast height increment cores. Significant correlation was observed among the three methods in identifying the demarcation point. However, the results indicated that EW-LW demarcation points identified using the three methods in juvenile wood rings were different to mature wood rings; with the most pronounced differences being observed for Mork’s index.

Genetic effects on wood quality traits of plantation-grown white spruce (Picea glauca) and their relationships with growth

Clonal repeatabilities on individual tree (\( H_i^2 \)) and clonal mean (\( H_{{\overline C }}^2 \)) bases for growth (14-year height and volume), wood quality traits (latewood proportion, wood density, fiber length, and microfibril angle), and genotypic correlations among the traits were estimated, using 30 white spruce (Picea glauca [Moench] Voss) clones from six full-sib families (five per family). These families were selected from a clonally replicated test to represent different early growth categories: fast, moderate, and slow. Wood increment cores of the 30 clones were collected from two contrasting sites at age 19 years. For growth traits, in contrast to most wood quality traits, more genetic variation was accounted for by clone within family than by family within growth category. Both growth and wood quality traits appear to be under moderate genetic control, with \( \widehat{H}_i^2 = 0.20 - 0.36 \) and \( \widehat{H}_{{\overline C }}^2 = 0.70 - 0.83 \). The only exception was microfibril angle (\( \widehat{H}_i^2 = 0.10\;{\text{and}}\;\widehat{H}_{{\overline C }}^2 = 0.34 \)). Generally, faster growth resulted in a significantly lower latewood proportion and lower overall wood density. Selection for faster growth does not appear to impact on either fiber length or microfibril angle. Among the wood quality traits, significant genotypic association was observed only between latewood proportion and wood density. Despite the generally negative association between growth and wood density among families, several fast-growing clones maintained above-average density. This implies that, by adopting multiclonal forestry, one can simultaneously improve growth and wood density.

Genetic variation in Pinus brutia Ten.: Wood density traits

Trees in two provenance-progeny experimental sites of Pinus brutia Ten. were sampled to study variation in wood density and its components among and within six populations and to estimate heritability of wood density and ring components. Wood increment cores (12 mm thick) were collected from 29-year-old trees at breast height. A total of 1023 wood strips were scanned with the X-ray densitometry technique. There were significant differences among populations and among families (within populations) in all the characters studied. Murtbeli (M) population from the middle altitude (486 m asl) had the highest values in both ring-area-weighted density and late wood proportion (500 ± 2.7 kg/ m3 and 49 ± 0.3 %, respectively), whereas Hacibekar (H) population from the highest altitude (1032 m asl) exhibited the lowest values (468 ± 3.0 kg/ m3, 42 ± 0.3 %). Relatively high heritability values (hi2 between 0.45 and 0.74; hhs2 between 0.68 and 0.80) for investigated characters (except latewood density) suggest that these characteristics are under moderate to strong genetic control, and thus, by selecting populations (and families within populations) having high wood density, genetic improvement can be achieved in P. brutia. Correlations between wood density and other growth traits have indicated that simultaneous selection of desired genotypes for most of the wood density components is possible for the species. Latewood percentage and earlywood density present an optimal target for selection to improve wood density.

Density of juvenile and mature wood of selected coniferous species

The objective of research was to determine the density of juvenile (JW) and mature wood (MW) of selected coniferous species growing in the Czech Republic. The research included the wood of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and European larch (Larix decidua Mill.). The juvenile wood density close to the pith was 410 kg·m<sup>–3</sup> for spruce, 391 kg·m<sup>–3</sup> for pine and 573 kg·m<sup>–3</sup> for larch with 12% water content. Mature wood in the peripheral parts had the higher density in all species – spruce 516 kg·m<sup>–3</sup>, pine 552 kg·m<sup>–3</sup> and larch 652 kg·m<sup>–3</sup>. The highest difference, the difference of 161 kg·m<sup>–3</sup>, between juvenile and mature wood was found out in Scots pine. The large difference in the wood density of pine is caused by a considerable difference in the mean ring width of its juvenile and mature wood. Further, it was proved that wood density decreases with the increasing ring width while wood density increases with the increasing proportion of latewood.

Xylem and phloem formation in chestnut ( Castanea sativa Mill.) during the 2008 growing season

Cambial activity and the dynamics of xylem and phloem formation were monitored during the 2008 growth season in five chestnut ( Castanea sativa) trees growing near Viterbo, Italy. The study was based on microscopic observations of micro-cores taken from stems at weekly intervals from mid-April until mid-October 2008. These observations allowed us to identify the timing of xylem and phloem formation. Cambial divisions, xylem and phloem formation had already started before the first sampling. By the end of April, the first earlywood vessels were already lignified and in early phloem the first formed sieve cells had finished postcambial growth. Formation of earlywood was completed by the end of May, which was about 2–3 weeks earlier than the completion of early phloem. The highest production of xylem cells was recorded between mid-May and mid-June and of phloem ones from mid-June until mid-July. Wood and phloem production mainly terminated in the middle of August while differentiation of xylem cells lasted until mid-October. The phloem ring was completed by the beginning of October 2008. Xylem growth rings were on average 2027 ± 635 μm wide and phloem rings 265 ± 68 μm. The proportion of latewood was 73 ± 8% and of late-phloem 49 ± 11%.

Wood properties of young Douglas-fir in Southern Italy: results over a 12-year post-thinning period

This paper describes the study of a 31-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand located in Southern Italy, which was thinned 19 years after planting. The aim of the study is to evaluate the influence of three thinning treatments (unthinned, selective, and geometrical) performed twelve years later on wood density (WD), moisture content, shrinkage, ring width (RW), latewood proportion (LW%), modulus of elasticity, compression (CS), and bending strength (BS). The WD was higher in the unthinned stand. LW% and BS were lowest in the selective thinning and in the geometrical thinning, respectively. No significant differences were found in other variables. In addition, the thinning processes mostly affected the medium tree class more than the dominant and suppressed ones. Regression analysis established a correlation between mechanical characteristics and WD, RW and LW%. Mechanical strength is strongly correlated with WD than other variables. The stepwise model showed that WD and RW are most closely related to the behavior of CS, whereas only WD explained variation in BS. Stand density reduction may improve the development of stands without greatly affecting wood quality.

Damage of the cell wall during extrusion and injection molding of wood plastic composites

To study material damage in wood cells during any transformation process, one must consider the molecular architecture of natural cellulosic fibers, which may eventually impact the overall mechanical behavior of wood fibers. In particular wood species, anatomical features and mechanical properties of the cell wall may determine the potential for stress transfer in hybrid materials. In this study, we quantified wood cell damage in terms of the stiffness reduction of the S2 layer for the cell wall by measuring Young’s modulus with nanoindentations of the cell wall before and after processing. We then propose and validate a modified rule of mixtures based on a damage parameter affected by the latewood proportion and cell wall properties.

Ring width, latewood proportion and density relationships in black locust wood of different origins and clones

Cross-sectional discs were cut at breast height from 19 black locust trees aged 18–39 years of different clones and origin (Greece, Bulgaria and Hungarian clones J, U and NY). Ring width, latewood proportion and dry density were measured according to standard laboratory techniques in order to examine their relationships. Latewood proportion was found to increase (except for one tree from Bulgaria) with increasing ring width and logarithmic equations were calculated with relatively high correlation coefficients. A positive relation between dry density and latewood proportion was found in black locust of Bulgarian origin and in the Hungarian clone NY while in all other cases no meaningful relationship was observed. In mature wood, improved positive linear correlations were observed between dry density and latewood proportion with the exception of the Hungarian clone U. Regression analysis revealed low correlations between dry density and ring width and only black locust from Bulgaria had a high positive correlation. The positive correlations between dry density and ring width were slightly improved in mature wood with the exception of clone J from Hungary.

Relationships of density, microfibril angle, and sound velocity with stiffness and strength in mature wood of Douglas-fir

The relative importance of density, acoustic velocity, and microfibril angle (MFA) for the prediction of stiffness (MOE) and strength (MOR) has not been well established for Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco). MOE and MOR of small clear specimens of mature wood were better predicted by density and velocity than by either variable alone (183 trees >20 years old, six specimens per tree, 1087 specimens total). Specimens sampled around the stem circumference had similar density (intraclass correlation coefficient t = 0.74) but not MOE (t = 0.40) or acoustic velocity (t = 0.32), indicating benefits from sampling several circumferential positions. For MOE, the path coefficients (β) were moderate for density and velocity. For MOR, β was only high for density. End-matched samples of one specimen per tree were analyzed with SilviScan. Simple correlations with MOE were highest for density (r = 0.67) and then acoustic velocity2 (0.53), MFA (–0.50), earlywood MFA (–0.45), and latewood proportion (0.40). Most correlations were weaker for MOR. Density had a higher β than did MFA for either MOE or MOR. In more complex path models, latewood proportion and latewood density were the most important contributors to MOE and MOR, and MFA was relatively unimportant. The path analyses showed what simple correlation did not: that latewood proportion has strong predictive value for Douglas-fir mature wood quality.

Relations entre climat et caractéristiques cellulaires dans la tige et les racines de l’épinette noire et du sapin baumier

• The anatomical differences of mature black spruces and balsam firs were examined at stem and root level in order to characterize their wood properties at cellular level and link these differences to climate. • Anatomical variability of these species was evaluated in relation to climate data gathered from 2001 to 2004 during the cell enlargement (CE) and wall thickening and lignification (WTL) phases. Lumen area, single cell wall thickness and total tracheid radial diameter were analyzed and regrouped into earlywood and latewood. • Results from a principal component analysis (PCA) indicated that both first eigenvectors account for 82% and 90% of total variance for CE and WTL respectively. These component factors revealed that precipitation, humidity and number of days with precipitation significantly influence the lumen area (p = 0.0168) and radial cell diameter (p = 0.0222) in earlywood. Significant differences were registered between species and tree parts (stem and root) for the lumen area, radial cell diameter and cell wall thickness in both earlywood and latewood. • In our study, black spruce exhibited smaller tracheid size in both stem and roots compared to balsam fir. Furthermore, the lower amount of tracheids produced during the growing season and higher proportion of latewood ensure a higher wood density of black spruce. The influence of temperature on earlywood formation is significant, whereas no influence was observed on latewood.

Ring width, latewood proportion and dry density in stems of Pinus brutia Ten.

This study examined basic characteristics of stem wood produced in Pinus brutia Ten. reforestations in Northeastern Greece. Sixteen dominant trees growing at good and medium site qualities were felled at 14–22 years. Site quality classification was based on site quality surrogates and confirmed by using site index curves that were created for a neighbouring area. Discs were taken at three stem positions (base, middle, top) to study variations in ring width, latewood proportion and dry density. Generally, at both good and medium sites, ring width was found to increase towards the top of the stems while latewood proportion and dry density showed a negative relationship with stem height. Radial variability trends were similar at all heights, and at both sites, revealing a rapid increase for ring width in the first 3–6 annual rings followed by a decrease towards the bark, a gradual increase for latewood proportion and no specific change for dry density. Comparisons between wood material produced during the same growth period (2005–2001) showed statistically significant differences among sampling heights in all cases except for dry density in medium sites. At the base of the stems, mean ring width and dry density were significantly (P ≤0.05) higher at good sites (3.6 mm and 0.53 g/cm3) than at medium sites (3.0 mm and 0.50 g/cm3). However, the differences between the sites are of small magnitude and therefore have limited practical impact on wood processing. The availability of such data is useful in utilising small-dimension timber of brutia pine.

Future wood and fibre sources – case North Karelia in eastern Finland

Information on the potential wood supply is important for the wood industry. In this study, the future development of growing stock, cutting potential and wood properties corresponding to the regional scenario of North Karelian Forest Programme 2006–2010 was analysed. The simulations were performed by employing the Finnish MELA system together with the sample plot and tree data of the 9th Finnish National Forest Inventory (NFI9) as initial data for the simulations. Disc-based models for basic wood density, proportion of latewood and fibre length of Norway spruce and Scots pine in Sweden were calibrated and integrated into the MELA system. The wood properties at breast height of both harvested and standing trees were analysed in different strata (age, site type and cutting method) during the scenario period of 50 years (2002–2052). The average wood properties within the same strata varied only slightly over time. However, the results for different strata differed considerably. In general, wood density, fibre length and proportion of latewood increased, on average, as a function of tree age and along with a decrease in site fertility (excl. wood density and proportion of latewood in harvested Norway spruce in the first case and fibre length in the latter case for both species). For trees less than 80 years, properties in harvested trees were equal to or slightly greater than those of standing trees. The values for clear-cuttings were greater or equal to those of thinnings (excl. wood density and proportion of latewood in Norway spruce). The study demonstrates the value of model-based analyses utilising NFI tree measurements in regions that are considered to be sources of raw material.

Effects of thinning and fertilization on wood properties and economic returns for Norway spruce

The effects of silviculture on wood and tracheid properties, and economic returns of Norway spruce ( Picea abies (L.) Karst.) were investigated in two case studies, one comparing different thinning intensity in southeastern Finland and the other considering the effects of optimal nutrient addition in northern Sweden. Models for predicting the wood and tracheid properties of Norway spruce were integrated into a distance-independent process-based growth and yield model. Increasing the thinning intensity resulted in a lower mean wood density, tracheid length, and latewood proportion in harvested wood. Wood density and tracheid length of harvested pulpwood slightly decreased in later thinnings and final cuts. Thinning regimes with high early growing stock and decreasing later growing stock were most profitable. Nutrient addition accelerated volume growth and increased the value growth. The increase in volume growth due to nutrient addition more than offset the economic influence of the loss in wood density and tracheid length.

What is hot in tree rings? The wood density of surviving Douglas-firs to the 2003 drought and heat wave

In a global warming scenario, drought and heat waves like the one that occurred in 2003 in Europe are expected to become more intense and frequent. This extreme climate event strongly affected the hydraulic balance in many forest tree species including Douglas-fir, with symptoms ranging from partial crown necrosis to death. We studied a French Douglas-fir provenance trial, strongly affected by the 2003 drought and heat wave. Using wood X-ray microdensity profiles as a record of cambium response to environmental variations, we compared mean stem density and growth between dead and alive neighbouring trees and several microdensity characters measured over 17 growth rings previous to 2003. Special attention has been given to the sampling layout in order to minimize the micro-environmental effects. At tree level, surviving trees have a significantly higher mean stem density. At tree ring level, they have a significantly higher mean ring density, maximum ring density, latewood density and, to a lesser extent, latewood proportion. No significant difference was found for diameter growth. These results could have direct implications in the way to study and predict possible acclimation and adaptation of forest trees to climate change process. Wood could be used for the selection of genotypes with a desirable plasticity and resistance to drought induced-cavitation.

Prediction ofPinus sylvestrisclear-wood properties using NIR spectroscopy and biorthogonal partial least squares regression

Thirteen wood parameters were predicted using near infrared (NIR) spectra in the range 780–2380 nm modelled by biorthogonal partial least squares regression. The analysis of parameters and NIR measurements was done on clear-wood samples from the base and midstem of Scots pine ( Pinus sylvestris L.) from trees at two sites. Calibrations based on the measured parameters at seven growth rings (cambial age ranging between 6 and 42 years) could be divided into three groups: (i) the best accuracy was found for longitudinal modulus of elasticity (r > 0.9) followed by bending, compression, and cell length (0.8 < r < 0.9); (ii) microfibril angle, longitudinal hardness, proportion of latewood, and creep with correlations in the range of 0.7–0.8; and (iii) tangential hardness, cell diameter, and cell wall thickness with 0.4 < r < 0.7. It was also shown that juvenile (cambial age ≤20 years) and mature wood can be classified using NIR techniques.

Latitudinal variation in tree-ring and wood cell characteristics of Picea mariana across the continuous boreal forest in Quebec

Wood anatomical features measured in tree-rings are useful indicators of environmental change and wood quality. The effect of latitude on the wood anatomy of mature black spruce ( Picea mariana (Mill.) BSP) was investigated along a 500 km transect from 47°N to 52°N across the continuous boreal forest in Quebec, Canada. Total tree-ring width, earlywood width, latewood width, latewood proportion, cell numbers, tracheid length, radial diameter, lumen diameter, and cell wall thickness were measured using image analysis on samples from 15 mature stands. Our results suggest that tree-ring, earlywood, and latewood widths, cell numbers, latewood radial cell diameter, and cell wall thickness decrease with latitude. No significant trend was observed for latewood proportion, despite a slight increase with latitude (p = 0.0856). However, the high variability in radial growth seen along the gradient might explain the absence of a significant relationship. Latitude and the associated growth rate reduction had no effect on tracheid length. The existence of a latitudinal pattern of variation in black spruce wood anatomy may be the result of tree adaptation to differing environmental conditions along the gradient.