Latewood Proportion Research Articles

The Distance to Which Wound Effects Influence the Structure of Secondary Xylem of Decapitated Pinus pinea.

Decapitation of stems of annuals and trees for the study of vascular and fiber differentiation with or without hormonal application is a common procedure. There is controversy about whether wound effects play a role in such experiments, and to what distance from the point of decapitation. To examine this question, the distance from the point of decapitation at which apparent wound effects are obvious developmentally, was studied in decapitated 4-year-old Pinus pinea plants. The wound effects just below the cut included differentiation of many traumatic resin ducts, a parenchyma band instead of tracheids, more tracheid files, and a higher proportion of late wood. The increase in the number of resin ducts was still considerable and statistically significant 10 cm below the point of decapitation compared with the nondecapitated control. These results indicate that in pines, wound effects in the first 5 cm below the decapitation point (a common point for tissue examination) cannot be ignored in experiments on the regulation of vascular differentiation.

Effects of live crown on vertical patterns of wood density and growth in Douglas-fir

It would be valuable economically to know what are the biological triggers for formation of mature wood (currently of high value) and (or) what maintains production of juvenile wood (currently of low value), to develop silvicultural regimes that control the relative production of the two types of wood. Foresters commonly assume the bole of softwoods produces juvenile wood within the crown and mature wood below. We tested that assumption by comparing growth ring areas and widths and wood density components of the outer three growth rings in disks sampled from different vertical positions of 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. The 18 trees were sampled from one site and had a wide range of heights to live crown. Most of the variance (63–93%) in wood characteristics (growth ring area: total, earlywood, latewood; growth ring width: total, earlywood, latewood; latewood proportion: by area, width; and ring density: total, earlywood, latewood) was due to within-tree differences (related to age of the disk). Stepwise regression analysis gave us equations to estimate wood characteristics, after which we analyzed the residuals with a linear model that included whether a disk was within or below the crown (defined as the lowest node on the stem with less than three live branches). After adjusting for tree and disk position, only 2–10% of the residual variation was associated with whether the disk was in or out of the live crown. There were no statistically significant differences at p = 0.05 between a given disk (by node number) in versus out of the crown for any of the factors studied. Moreover, the wood density characteristics were not statistically significant at p = 0.30. This research suggests that there was no effect of the crown position on the transition from juvenile to mature wood as judged by wood density. Therefore, we found no evidence to support the concept that tree spacing and live-branch pruning have a significant effect on the cambial age of transition from juvenile to mature wood in Douglas-fir trees of this age.

Wood-density variation of Norway spruce in relation to nutrient optimization and fibre dimensions

The effect of fertilization on wood density, fibre length, fibre diameter, lumen diameter, proportion of cell wall area, and cell wall thickness of Norway spruce (Picea abies (L.) Karst.) were studied in a nutrient optimization experiment in northern Sweden. On the fertilized plots, all essential macronutrients and micronutrients were supplied in irrigation water every second day during the growing season. After 12 years' treatment, data were collected from 24 trees (40 years old) on the fertilized and control plots. Fertilization increased radial growth more than threefold, especially earlywood width, and decreased wood density by over 20% at 1.3 and 4 m height. The decrease in wood density was closely related to the proportion of latewood. The absolute wood density also decreased across the whole annual ring but proportionately more in latewood than in earlywood. A close relationship was found between the wood density and fibre properties, especially with the proportion of cell wall in a cross section of each annual ring, as well as with fibre and lumen width. The absolute cell wall thickness was clearly less related to wood density. However, rather large variations were found between individual trees in the relationship between wood density and fibre properties.

THE INFLUENCE OF COMPRESSION WOOD ON THE DRYING CURVES OF PINUS RADIATA DRIED IN DEHUMIDIFIER CONDITIONS

ABSTRACT Measurements of drying rate of Pinus radiata at 55°C and 30% RH are presented. The data, which has been used to establish empirical models for P. radiata under dehumidifier drying conditions, was obtained in four drying runs in a drying tunnel, each yielding detailed drying curves for twelve sample sapwood boards of size 350 × 100 × 50 mm. Compression wood was found to have a significant effect on the drying rate curve, giving lower drying rates at 40–100% MC. This effect is interpreted through the use of a numerical multiple-mechanism two-zone model and quantified by using best-fit diffusion parameters from an isothermal diffusion model. A positive correlation was discovered between the moisture diffusion coefficient and initial moisture content, a strong indicator for the presence of compression wood. In the two-zone model, the compression wood effect was replicated by using a tenfold decrease in permeability to liquid flow. Attributes of compression wood that could cause reduced permeability include an increased proportion of latewood, narrower lumen, and a scarcity of bordered pits on the radial walls of longitudinal tracheids.

The wood quality ofPinus chiapensis(Mart.) Andresen grown in the Mpumalanga forest region

Synopsis The ten best performing families selected in a Pinus chiapensis trial at Tweefontein forest near Sabie have been evaluated for wood and saw timber properties. The wood was found to be soft, remarkably uniform both within and between annual rings, stable, with a well-defined heartwood zone. The latewood proportion of the annual rings was extremely small, resulting in a poorly defined ring structure. The fifty trees studied had an average air-dry density of 0,420 g/cm3(extracted and at 12 % moisture content) with individual tree densities varying from 0,380 to 0,465 g/cm3 at 0,8m height level. Differences between families were highly significant, suggesting that there is a strong potential to increase the density of the woodthrough tree breeding. Knots were relatively small and well shaped, and normally occurred in small clusters. Knot occlusions following pruning were accompanied by little grain distortion. When present, the amounts of included resin, pieces of bark and other debris at the occluded pruning cuts, were small and oflittle practical significance. The wood machined without any difficulty in the wet and dry condition. Boards dried without any significant drying degrade, but moisture loss during drying from the heartwood zone was markedly slower compared to what is normally experienced with the pith zone of other South African commercial pines. Some sawn pieces may not be suitable for some structural purposes where strength is important, while tests on Colombian and Brazilian grown P. chiapensis have shown that the species may not be acceptable for pulp production because oflow pulp yields and high alkali consumption. Owing to its high degree of uniformity it might be well suited for special products such as for internal construction purposes, panelling and other decorative work, woodcarving and some applications in the furniture manufacturing industry. It might also be suitable for the manufacturing ofitems such as match sticks, toothpicks, clothes-pegs and other small wooden objects.

The Effect of Varying Latewood Proportion on the Radial Distribution of Lignin Content in a Pine Stem

Summary The radial distribution of lignin content in a pine stem was compared to latewood proportion. With the exception of the innermost juvenile growth rings, a strong negative correlation was found. However, the cell-wall lignin content of low lignin growth rings was equal to that of high-lignin growth rings. Therefore, the difference in lignin content between individual growth rings was solely due to varying ratios of high-lignin compound middle lamella to low-lignin secondary wall in thin- and thick-walled tracheids.

The effects of cambial age and position within the stem on specific conductivity in Douglas-fir ( Pseudotsuga menziesii) sapwood

Specific conductivity (k s, m2s–1MPa–1) describes the permeability of xylem and is determined by all aspects of xylem anatomy that create resistance to the flow of water. Here we test the hypothesis that k s is a function of radial and vertical position within the stem, rather than solely a function of cambial age (ring number from the pith), by measuring k s on samples excised from 35-year-old Douglas-fir [Pseudotsuga menziesii var. menziesii (Mirb.) Franco] trees at six heights and two or three radial positions. Sapwood k s decreased from the cambium to the heartwood boundary, and the difference between outer and inner sapwood increased with height in the tree. Beneath the live crown, inner sapwood had 80–90% the k s of outer sapwood, but only 55% just 10 m higher in the stem (about 10 nodes down from the tree top). Outer sapwood k s peaked near the base of the crown and declined toward both the base and top of the stem. These patterns can be explained by two superimposed effects: the effect of cambial age on the dimensions of tracheids as they are produced, and the effect of xylem aging, which may include accumulation of emboli and aspiration of bordered pits. Tracheid lumen diameter and earlywood and latewood density and width, all factors known to vary with cambial age, were measured on different trees of the same age and from the same stand. Lumen diameter increased with cambial age, whereas the proportion of latewood and growth ring density increased after an initial decrease in the first 5 years. Our results suggest that the effect of cambial age on xylem anatomy is not sufficient to explain variation in k s. Instead, physical position (both vertical and radial) in the stem and cambial age must be considered as determinants of conductivity.

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A COMPARISON OF TREE-RING FEATURES IN PICEA ABIES AS CORRELATED WITH CLIMATE

This paper presents an analysis of 16 anatomical variables measured on 20 spruce trees [Picea abies (L.) Karst.] from sites in the managed forest district Seyde, Eastern Ore Mountains, south of Dresden, Germany. Ring width and latewood proportion did not show significant relationships with monthly climatic data, whereas maximum density, latewood cell-wall proportion and latewood density were highly correlated with temperature and precipitation. The climatic signals expressed in resin duct density, ray height, tracheid length and microfibril angles were less pronounced. Of 16 tree-ring parameters, densitometry – as an indirect measure of xylem anatomy – has again shown its great potential to record climatic conditions.

The response of black spruce to the climatic influence of Robert-Bourassa Reservoir in northern Québec

Do large hydroelectric reservoirs in northern Québec have an influence on regional climate? In the absence of any climatic record covering the period prior to and after damming, the influence of a reservoir was studied by means of tree rings. The objective of this research was to determine the reaction of black spruce to local climate change. The study was carried out on an island in the second-largest reservoir of the La Grande complex in the James Bay area, the Robert-Bourassa Reservoir (2835 km2), which is also the oldest (dammed in 1978 and completely flooded in September 1979). Trees (n = 14) about 100 years old were selected by means of two perpendicular transects on the island. Cross sections were cut at 1-m intervals at the base of trees, and at 10-cm intervals in the top section of the stem which developed during the last 30 years. Densitometric analysis was performed on each section. Results were compared with two reference chronologies using the same tree-ring parameters. Reference stands were selected outside the area of climatic influence of the reservoir. The identified tree-ring indicators of reservoir local climate were (i) absence of frost rings, despite their abundance outside the reservoir’s area of influence, due to a delayed growing season caused by local cool conditions; (ii) high frequency of light rings related to cooler summer conditions; (iii) large numbers of trees showing compression wood sequences indicating destabilization due to windier conditions associated with the increased fetch; (iv) lower annual wood production; (v) degradation of tree growth forms marked by massive foliage loss and branch mortality; and (vi) reduced wood density, despite increased proportion of latewood. The number of trees that showed these six tree-ring indicators was a function of distance to water and stand density.

Selection for height growth and Pilodyn pin penetration in lodgepole pine: effects on growth traits, wood properties, and their relationships

The effects of selection using indices of height growth and wood density based on Pilodyn pin penetration (PIN) and the relationships among growth traits and wood properties were investigated in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.). Four subpopulations were constructed by selecting 10 open-pollinated families in each of four categories: (i) fast height growth and high wood density, (ii) slow height growth and high density, (iii) fast height growth and low density, and (iv) slow height growth and low density. Eleven-year growth, PIN, and wood-density traits generated from X-ray densitometry were analyzed. We found that selection of subpopulations using indices of height and PIN resulted in significant differences among subpopulations in most growth and wood-density parameters. However, PIN underestimated the wood density of families with large diameter. Disk density was found to be moderately negatively correlated with diameter growth, weakly negatively correlated with stem volume, but not significantly correlated with height. Selection for latewood proportion to improve wood density in lodgepole pine is likely to result in a reduction in growth and biomass production; however, selection for total latewood volume or simply height has the potential to increase both growth and wood density.

Age trends in genetic parameters of wood density in young Norway spruce

Age trends of phenotypic, environmental, and additive genetic variance and heritability were estimated for overall density and its components earlywood and latewood densities and latewood proportion. The objective was to acquire information for both individual and cumulated rings from ring number 3 to 12 counted from the pith. Age-age correlations were calculated for cumulated density traits only. The wood density data were obtained with X-ray analysis of increment cores from 47 open-pollinated families of Norway spruce (Picea abies (L.) Karst.). The families had earlywood and latewood with significant differences in density for individual and cumulated rings and consequently for overall density. The latewood proportion had significant family variation for cumulated rings but not for all individual rings. Large fluctuations in environmental variance caused fluctuations in heritability estimates for successive rings. A strong decrease in environmental variance for all cumulated traits, especially from ring 3 to 5, resulted in a steady increase in heritability estimates. The latewood density had the highest heritability estimates and latewood proportion the lowest for both individual and cumulated rings. Overall density and the cumulated components at cambial age 12 showed strong genetic correlations with their respective traits at all younger ages.

Influence of Rainfall, Irrigation and Age on the Growth Periodicity and Wood Structure in Teak (Tectona Grandis)

Growth periodicity was followed for two consecutive annual cycles to reveal the pattern of wood fonnation in plantation-grown teak at three different localities in India. Rainfall and age were the two important factors that influenced cambial activity. Cambial reactivation occurred during March-April in both years. The pre-monsoon showers broke the cambial donnancy at all three localities. Almost a month's interval was observed between bud break and initiation of radial growth . Irrespective of age and locality, a peak period of cambial activity occurred during June-July. Dormancy began during October-December, depending on the age of the trees and locality. Juvenile trees and those grown in relatively high rainfall areas had a prolonged cambial activity and retained foliage throughout the year. They produced wider rings with higher proportions of latewood. Irrigation of 5-year-old trees led to the loss of typical ring porosity of teak wood; their first three growth rings were more or less diffuse-porous. This is attributed to uninterrupted cambial activity resulting in production of rather uniform-sized vessels.

Relationship between Wood Anatomical Properties and Specific Permeability of Sugi (Cryptomeria japonica) Sapwood and Intermediate Wood

The objective of this study was to clarify anatomical factors which determine specific permeability of sapwood and intermediate wood in air-dried sugi (Cr?~ptomeria juponica) wood. Superficial air permeability of sugi sapwood and intermediate wood was measured and then specific permeability was determined. Using these specimens for permeability tests, the proportion of latewood and earlywood, the percentage ol aspirated and incompletely aspirated pits, the number of bordered pits per tracheid, the number of tracheids per unit area and tracheid length were obtained. Specific permeability decreased with increasing levels in the stcm except for the lowest level and also related to distance from pith, suggesting that cambial age is related to specific permeability. A clear relationship between percentage ol latewood and specific permeability was not found, suggesting that effective pathways in earlywood determines permeability. Specific permeability of intermediate wood and sapwood were significantly related to the number of effective open pits in earlywood, Mi3J, which was determined by anatomical properties such as aspirated and incompletely aspirated pits, the number of pits and tracheids, and proportion of latewood, suggesting that specilic permeability of sugi sapwood and intermediate wood is a physical value determined by the intrinsic properties of earlywood in addition to the condition of bordercd pits.

Influence of structural parameters on the nondestructive evaluation of ash timber (Fraxinus excelsior L.)

The aim of this project is to analyse the influence of wood structure of ash timber products — as a result from different growth rates — on their performance, if nondestructive evaluation is applied. To do this, 261 beams have been tested with the method of natural frequency on flexural vibration. The following anatomical and structural parameters have been documented as independent variables on all tested beams: annual ring width, proportion of latewood, ring position, grain orientation, presence or absence of heartwood and other discolourations as well as the positions and dimensions of knots. The values obtained from the nondestructive evaluation have been put into relation with the MOR obtained through final destructive 4-point-bending test of all beams. The influence of the wood structure on this relationship has been analysed either with univariate regressions between single structural parameters and MOR, or including more than one of these structural parameters in multivariate regression models. The regressions between nondestructive parameters and MOR present lower levels of determination than the usual determination levels reported for softwood timber. For the ringporous species ash the influence of the wood structure could be more significant than for the more homogeneous wood structure of coniferous species and, consequently, should be analysed in detail. The main results of this analysis show only minimal influence of the ring structure and of the grain angle on the relationship between nondestructive values and MOR. The presence of heartwood does not influence this relationship. By far the most important parameter is the presence or absence of knots. Different knot parameters were measured and included into the models: KAR and vectorial models of position and dimension of the knots. This detailed measurement of the knots and its inclusion into multiple regression models allow a significant increase of the total level of determination and consequently an improved nondestructive quality assessment of ash timber products. Consequences for the practical application of the results in industrial sawmilling are considered.

Variation in wood structure of eastern larch defoliated by the larch sawfly in subarctic Quebec, Canada

We studied the wood structure of eastern larch (Larixlaricina (Du Roi) K. Koch) affected by a larch sawfly (Pristiphoraerichsonii (Htg.)) infestation that occurred in 1939 in the Lac à l'Eau-Claire and Rivière-aux-Mélèzes areas, subarctic Quebec. The objective was to document variation in wood characteristics in relation to defoliation at three study sites. Lumen diameter of tracheids and cell wall thickness were measured from thin sections representing the 1931–1955 period. Significant changes in the wood structure of larch was noticed only at the Atkinson Island site, where the radial growth pattern was typical of the insect activity. A light ring was formed the 1st year of the infestation (1939). During the 2nd year (1940), the size of tracheids (lumen) decreased abruptly along with radial growth, while the proportion of latewood increased. The variation in wood anatomy among the three study sites paralleled that in radial growth. Wood structure appears to be a good indicator of the end of an infestation.

Breast-height relative density and radial growth in mature jack pine (Pinusbanksiana) for 38 years after thinning

Sawlogs are in short supply in northern Ontario, and thinning has been suggested as one way to improve the situation. The only rotation-age jack pine (Pinusbanksiana Lamb.) thinning trial in the region was examined to assess how commercial thinning influenced wood quality. This report covers an unreplicated trial of a 65-year chronology of pith to bark relative densities and growth rates based on X-ray densitometry of breast-height increment cores taken from trees on two thinned plots (average spacing 2.6 and 3.4 m) and an unthinned control (average spacing 1.7 m). The trees on the treatment plots responded to thinning by producing wood with significantly lower relative density than those on the control plot. This trend continued much longer than reported for other pines and could negatively affect pulp yield or mechanical properties of lumber. Enhanced earlywood growth caused a drop in the proportion of latewood that resulted in the decline in density. Thinning may have improved moisture availability during the early and middle season and encouraged earlywood growth. Density and growth rate differences became apparent soon after treatment. Early, rapid, and inexpensive estimates of the product potential of younger thinning trials are possible using the techniques demonstrated here.

Age-Age Correlations and Early Selection for Wood Density in Young Coastal Douglas-Fir

Abstract Age-age correlations and age-associated changes in the genetic control of wood density and its components (earlywood density, latewood density, and latewood proportion) were investigated in 15-yr-old trees of 60 open-pollinated families of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco). The possibility of using wood density components as secondary traits to increase the efficiency of early selection for overall wood density was also explored. Heritability estimates for overall density and its components increased with age, mainly because of a decrease in the error variance as the number of rings in the core sample increased. Overall density and its components at age 15 had strong genetic correlations with their respective traits at all younger ages analyzed. Moreover, with few exceptions, age-age genetic correlations were greater than phenotypic correlations. Early selection to improve overall density at age 15 was quite efficient (relative efficiency above 79%), even when selection was based on core density at the youngest age (age 7). Using wood density components as secondary traits produced a slight increase in the efficiency of early selection only at the youngest ages, presumably because age-age correlations for overall core density were already strong, limiting the possibility of additional improvement. For. Sci. 38(2):467-478.

Genetic variation of wood density components in young coastal Douglas-fir: implications for tree breeding

The genetic control of wood density components (earlywood density, latewood density, and latewood proportion) and their relationships with overall density in coastal Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) were examined to assess the usefulness of this information in breeding for wood density. The genetic relationships of wood density with intraring density variation and bole volume growth were also investigated. Increment cores were taken at breast height from 15-year-old trees of 60 open-pollinated families. Averages across each core for overall wood density, its components, and intraring density variation were determined by using X-ray densitometry. Bole volume at age 15 for the same trees was derived from tree height and diameter at breast height measurements. Although wood density components varied significantly among families and were under moderate genetic control (individual-tree heritability (hi2) > 0.24), none had a higher heritability than overall density (hi2 = 0.59). Density components had strong genetic correlations with overall density (r ≥ 0.74) but were also strongly related among themselves (0.57 ≤ r ≤ 0.92). Thus, density components have limited value in improving the efficiency of selection for overall density. Overall density was positively correlated with intraring density variation (r = 0.72) and negatively correlated with bole volume (r = −0.52). Comparison of several selection indices incorporating wood density and one or more growth traits, however, showed that it is possible to obtain substantial gains in bole volume without loss in (or even with a modest increase in) wood density. By restricting the response in wood density, the change in intraring density variation can also be limited.

Influence of environmental factors on the wood structure of living and fossil trees

The mechanism of wood development records in varying degree the effects of both external and internal factors that are operating at the time of development. As a result, fossil woods spanning the last 370 million years represent a unique palaeo-environmental data-store. Data concerning external factors that can be reclaimed consist of: presence or absence of growth rings; ring widths; relative proportions of earlywood and latewood and the nature of the transition between them; “false” and “frost” rings and evidence of damage by animals or fire; occurrence of reaction wood. These effects have to be seen against a background of the influences of the internal factors.