Scots pine responses to elevated temperature and carbon dioxide concentration: growth and wood properties

Growth and wood properties of 20-year-old Scots pine (Pinus sylvestris L.) trees were studied for 6 years in 16 closed chambers providing a factorial combination of two temperature regimes (ambient and elevated) and two carbon dioxide concentrations ([CO2]) (ambient and twice ambient). The elevation of temperature corresponded to the predicted effect at the site of a doubling in atmospheric [CO2]. Annual height and radial growth and wood properties were analyzed during 1997-2002. Physical wood properties analyzed included early- and latewood widths and their proportions, intra-ring wood densities, early- and latewood density and mean fiber length. Chemical wood properties analyzed included concentrations of acetone-soluble extractives, lignin, cellulose and hemicellulose. There were no significant treatment effects on height growth during the 6-year study. Elevated [CO2] increased ring width by 66 and 47% at ambient and elevated temperatures, respectively. At ambient [CO2], elevated temperature increased ring width by 19%. Increased ring width in response to elevated [CO2] resulted from increases in both early- and latewood width; however, there was no effect of the treatments on early- and latewood proportions. Mean wood density, earlywood density and fiber length increased in response to elevated temperature. The chemical composition of wood was affected by elevated [CO2], which reduced the cellulose concentration, and by elevated temperature, which reduced the concentration of acetone-soluble extractives. Thus, over the 6-year period, radial growth was significantly increased by elevated [CO2], and some wood properties were significantly affected by elevated temperature or elevated [CO2], or both, indicating that climate change may affect the material properties of wood.     

Wood properties of Scots pines (Pinus sylvestris) grown at elevated temperature and carbon dioxide concentration

Impacts of elevated temperature and carbon dioxide concentration ([CO2]) on wood properties of 15-year-old Scots pines (Pinus sylvestris L.) grown under conditions of low nitrogen supply were investigated in open-top chambers. The treatments consisted of (i) ambient temperature and ambient [CO2] (AT+AC), (ii) ambient temperature and elevated [CO2] (AT+EC), (iii) elevated temperature and ambient [CO2] (ET+AC) and (iv) elevated temperature and elevated [CO2] (ET+EC). Wood properties analyzed for the years 1992-1994 included ring width, early- and latewood width and their proportions, intra-ring wood density (minimum, maximum and mean, as well as early- and latewood densities), mean fiber length and chemical composition of the wood (cellulose, hemicellulose, lignin and acetone extractive concentration). Absolute radial growth over the 3-year period was 54% greater in AT+EC trees and 30 and 25% greater in ET+AC and ET+EC trees, respectively, than in AT+AC trees. Neither elevated temperature nor elevated [CO2] had a statistically significant effect on ring width, early- and latewood widths or their proportions. Both latewood density and maximum intra-ring density were increased by elevated [CO2], whereas fiber length was increased by elevated temperature. Hemicellulose concentration decreased and lignin concentration increased significantly in response to elevated temperature. There were no statistically significant interaction effects of elevated temperature and elevated [CO2] on the wood properties, except on earlywood density.     

Relationships among selected wood properties of 20-year-old Taiwania (<Emphasis Type="Italic">Taiwania cryptomerioides</Emphasis>) trees

The relationships between bending properties, compressive strength, tracheid length, microfibril angle, and ring characteristics of 20-year-old Taiwania (Taiwania cryptomerioides Hay.) trees were examined. The trees came from different thinning and pruning treatments, but the practices showed no significant effect on the investigated properties. The results showed that based on comparison with the literature, plantation-grown immature Taiwania have noticeably lower average strength properties than mature trees of the same species. Wood density and bending and compressive strengths were not related to either tracheid length or microfibril angle in young Taiwania. There were positive relationships between bending strength and compressive strength. The wood density, ring width, earlywood width, earlywood density, and latewood percentage were the most important predictors of strength by simple linear regressions. The wood density and ring width/earlywood width may be considered as indicators for assessing the bending strength, while wood density and latewood percentage were the best predictors of compressive strength by multiple linear regressions.     

日本落叶松无性系木材性质的遗传变异

对10个10年生日本落叶松无性系的木材基本密度、管胞参数进行了测定.结果表明:木材基本密度,早、晚材管胞宽度和早材长宽比无性系间差异显著;木材基本密度,早、晚材管胞长度,早晚材管胞宽度和早晚材长宽比径向变异模式相似,即从髓心向外以曲线形式不断增加,有时亦有起伏;早材从髓心向外以近似直线的形式缓慢增加,晚材从髓心向外以曲线形式增加,初期增加幅度较大,到一定年龄后趋于水平变化并略有波动;材质性状与树木年轮间的关系以对数方程、幂函数方程、指数方程拟合效果较好;除了晚材壁腔比和早材壁厚外,其它木材性质的重复力均在0.5以上,受中度或中度以上的遗传制约,按照20%的选择率,长宽比和晚材管胞长能获得较高的遗传增益.     

Control of tracheid cross-sectional dimensions in Norway spruce and Scots pine wood raw material

Abstract

Wood properties, including tracheid cross-sectional dimensions, show a large degree of variation. To improve the properties of products made from wood, different methods to control variation have been developed. This study aims to determine the theoretical efficiency of three control strategies: the fractionation of pulped tracheids into earlywood and latewood, the separation of juvenile and mature wood, and sorting of logs according to tree size. The efficiency of each method was studied by first constructing virtual trees from measured tracheid cross-sectional dimensions, then simulating the efficiency of above-mentioned methods. The tracheid dimension data include Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). The simulations show that separation into earlywood and latewood classes has the highest theoretical efficiency and yields the lowest variances in raw material. Classification into juvenile and mature wood groups is the second most efficient method, and the sorting of logs according to the size class of the tree is the least efficient method. It was also concluded that the variation in cell-wall thickness and radial diameter mainly originates from differences between earlywood and latewood, whereas the variation in tangential diameter mainly originates from differences between mature and juvenile wood.     

Hydraulic and mechanical properties of young Norway spruce clones related to growth and wood structure

Stem segments of eight five-year-old Norway spruce (Picea abies (L.) Karst.) clones differing in growth characteristics were tested for maximum specific hydraulic conductivity (k(s100)), vulnerability to cavitation and behavior under mechanical stress. The vulnerability of the clones to cavitation was assessed by measuring the applied air pressure required to cause 12 and 50% loss of conductivity (Psi(12), Psi(50)) and the percent loss of conductivity at 4 MPa applied air pressure (PLC(4MPa)). The bending strength and stiffness and the axial compression strength and stiffness of the same stem segments were measured to characterize wood mechanical properties. Growth ring width, wood density, latewood percentage, lumen diameter, cell wall thickness, tracheid length and pit dimensions of earlywood cells, spiral grain and microfibril angles were examined to identify structure-function relationships. High k(s100) was strongly and positively related to spiral grain angle, which corresponded positively to tracheid length and pit dimensions. Spiral grain may reduce flow resistance of the bordered pits of the first earlywood tracheids, which are characterized by rounded tips and an equal distribution of pits along the entire length. Wood density was unrelated to hydraulic vulnerability parameters. Traits associated with higher hydraulic vulnerability were long tracheids, high latewood percentage and thick earlywood cell walls. The positive relationship between earlywood cell wall thickness and vulnerability to cavitation suggest that air seeding through the margo of bordered pits may occur in earlywood. There was a positive phenotypic and genotypic relationship between k(s100) and PLC(4MPa), and both parameters were positively related to tree growth rate. Variability in mechanical properties depended mostly on wood density, but also on the amount of compression wood. Accordingly, hydraulic conductivity and mechanical strength or stiffness showed no tradeoff.     

人工兴安落叶松次生木质部的解剖学研究

运用木材解剖图像分析系统和显微照相的方法对人工兴安落叶松次生木质部的解剖结构进行研究,结果表明:落叶松具正常树脂道和受伤树脂道两种类型,前者常见于晚材。落叶松生长轮内的早晚材在干和枝内急变,在根内缓变。早材管胞呈六边形至多边形,胞壁常见单列具缘纹孔,偶见对列具缘纹孔;晚材管胞多呈矩形,胞壁鲜见具缘纹孔,通常为单列具缘纹孔。落叶松木射线同时具有单列木射线和纺锤形木射线两种类型,纺锤形木射线中仅含一枚纵行树脂道。纵行管胞与木射线交叉形成的纹孔场为云杉型。从根到干再到枝,管胞逐渐细化,管胞长度逐渐减小,木射线分布由密到疏。     

Age and weather effects on between and within ring variations of number,width and coarseness of tracheids and radial growth of young Norway spruce

Annual growth, fibre and wood properties of Norway spruce are all under strong influence from genetics, age and weather. They change dynamically, particularly at young ages. Most genetic research and tree improvement programs are based on data from this most dynamic phase of the life of trees, affected by differences in weather among sites and years. In the work presented, influences of age and weather were investigated and modelled at the detail of annual rings and at the sub-tree ring level of earlywood, transitionwood and latewood. The data used were analysed from increment cores sampled at age 21 years from almost 6000 Norway spruce trees of known genetic origin, grown on two sites in southern Sweden. The traits under investigation were radial growth, cell widths, cell numbers, cell wall thickness and coarseness as a measure of biomass allocation at cell level. General additive mixed models (GAMMs) were fitted to model the influences of age, local temperature and precipitation. The best models were obtained for number of tracheids formed per year, ring width, average radial tracheid width in earlywood, and ring averages for tangential tracheid width and coarseness. Considering the many sources behind the huge variation, the explained part of the variability was high. For all traits, models were developed using both total tree age and cambial age (ring number) to express age. Comparisons indicate that the number of cell divisions and ring width are under stronger control of tree age, but the other traits under stronger control of cambial age. The models provide a basis to refine data prior to genetic evaluations by compensating for estimated differences between sites and years related to age and weather rather than genetics. Other expected applications are to predict performance of genotypes in relation to site or climate and simulation of climate change scenarios.     

Relationships of climate and cell features in stems and roots of black spruce and balsam fir

? 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.

     

Studies on opposite wood in conifers part II: Histology and ultrastructure

Summary A study has been made of the histology and ultrastructure of opposite wood in Larix laricina, Picea rubens, and Pinus resinosa. The width of the growth rings varied considerably, in one case from 0.1–1.0 mm, with the wide rings containing a much higher proportion of latewood than the narrow ones. The earlywood tracheids were square in outline and more regularly arranged than in normal wood. In the latewood they were sometimes irregular and distorted. The S₃ layer in the tracheids was 0.2 m thick in the earlywood and 0.4–0.8 m in the latewood, as compared to a thickness in normal wood of 0.1–0.2 m in both zones. The S₃ was often buckled in the latewood and was terminated towards the lumen by a spiral thickening. The cell wall structure of the tracheid pit border was described. Normal coniferous wood might be regarded as an intermediate between opposite wood and compression wood.This paper is dedicated to Dean Edwin C. Jahn in honor of his 70th birthday.     

Intra-increment circumferential variation in tracheid length as a basis for sampling genetically superior trees of deodar (Cedrus deodara (Roxb.) Loud.)

Summary Intra-increment circumferential variation in tracheid length at breast-height in deodar (Cedrus deodara (Roxb.) Loud. vern. diar) has been studied with the main objective of evolving an efficient sampling procedure for the purpose of comparing tracheid length amongst individual trees of forest stands. It has been studied in five sampling strata namely: whole-annual ring, whole-earlywood, whole-latewood, first-firmed earlywood and last-formed latewood. Tracheid length shows significant circumferential variation in whole-annual ring, whole-earlywood, whole-latewood and last-formed latewood. However, when the mean tracheid length of two opposite directions is compared with the mean tracheid length of eight cardinal directions in these sampling strata, then no significant difference is observed. First-formed stratum of an annual ring exhibits statistically consistent values around the circumference and thus sampling from any random radial direction can serve the purpose for the comparison of inherent values of tracheid length amongst the deodar trees.The financial assistance given by Himachal Pradesh University as H.P.U. Junior Research Fellowship to second author is highly acknowledged     

Sapwood development in Pinus radiata trees grown for three years at ambient and elevated carbon dioxide partial pressures

Clonal trees of Pinus radiata D. Don were grown in open-top chambers at a field site in New Zealand for 3 years at ambient (37 Pa) or elevated (65 Pa) carbon dioxide (CO2) partial pressure. Nitrogen (N) was supplied to half of the trees in each CO2 treatment, at 15 g N m-2 in the first year and 60 g N m-2 in the subsequent 2 years (high-N treatment). Trees in the low-N treatment were not supplied with N but received the same amount of other nutrients as trees in the high-N treatment. In the first year, stem basal area increased more in trees growing at elevated CO2 partial pressure and high-N supply than in control trees, suggesting a positive interaction between these resources. However, the relative rate of growth became the same across trees in all treatments after 450 days, resulting in trees growing at elevated CO2 partial pressure and high-N supply having larger basal areas than trees in the other treatments. Sapwood N content per unit dry mass was consistently about 0.09% in all treatments, indicating that N status was not suppressed by elevated CO2 partial pressure. Thus, during the first year of growth, an elevated CO2 partial pressure enhanced carbon (C) and N storage in woody stems, but there was no further stimulus to C and N deposition after the first year. The chemical composition of sapwood was unaffected by elevated CO2 partial pressure, indicating that no additional C was sequestered through lignification. However, independent of the treatments, early wood was 13% richer in lignin than late wood. Elevated CO2 partial pressure decreased the proportion of sapwood occupied by the lumina of tracheids by up to 12%, indicating increased sapwood density in response to CO2 enrichment. This effect was probably a result of thicker tracheid walls rather than narrower lumina.     

Cavitation in dehydrating xylem of Picea abies: energy properties of ultrasonic emissions reflect tracheid dimensions

Ultrasonic emission (UE) testing is used to analyse the vulnerability of xylem to embolism, but the number of UEs often does not sufficiently reflect effects on hydraulic conductivity. We monitored the absolute energy of UE signals in dehydrating xylem samples hypothesizing that (i) conduit diameter is correlated with UE energy and (ii) monitoring of UE energy may enhance the utility of this technique for analysis of xylem vulnerability. Split xylem samples were prepared from trunk wood of Picea abies, and four categories of samples, derived from mature (I: earlywood, II: 30-50% latewood, III: >50% latewood) or juvenile wood (IV: earlywood) were used. Ultrasonic emissions during dehydration were registered and anatomical parameters (tracheid lumen area, number per area) were analysed from cross-sections. Attenuation of UE energy was measured on a dehydrating wood beam by repeated lead breaks. Vulnerability to drought-induced embolism was analysed on dehydrating branches by hydraulic, UE number or UE energy measurements. In split samples, the cumulative number of UEs increased linearly with the number of tracheids per cross-section, and UE energy was positively correlated with the mean lumen area. Ultrasonic emission energies of earlywood samples (I and IV), which showed normally distributed tracheid lumen areas, increased during dehydration, whereas samples with latewood (II and III) exhibited a right-skewed distribution of lumina and UE energies. Ultrasonic emission energy was hardly influenced by moisture content until ～40% moisture loss, and decreased exponentially thereafter. Dehydrating branches showed a 50% loss of conductivity at -3.6 MPa in hydraulic measurements and at -3.9 and -3.5 MPa in UE analysis based on cumulative number or energy of signals, respectively. Ultrasonic emission energy emitted by cavitating conduits is determined by the xylem water potential and by the size of element. Energy patterns during dehydration are thus influenced by the vulnerability to cavitation, conduit size distribution as well as attenuation properties. Measurements of UE energy may be used as an alternative to the number of UEs in vulnerability analysis.     

Morphological changes in sugi (Cryptomeria japonica) wood after treatment with the ionic liquid, 1-ethyl-3-methylimidazolium chloride

We investigated morphological changes in wood tissues of sugi (Cryptomeria japonica) resulting from treatment with the ionic liquid 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), which dissolves cellulose. Treatment with [C2mim][Cl] caused dissociation and distortion of tracheids in latewood, but not in earlywood. This difference was due to the difference in swelling behavior of the cell wall between earlywood and latewood. Many pit membranes in bordered pits were broken by treatment with [C2mim][Cl]. In addition, some chemical changes in wood components, such as cellulose and lignin, occurred before significant disruption or destruction of the cell wall. Our results show that the reaction of wood liquefaction by [C2mim][Cl] treatment is not homogeneous, both from chemical and morphological viewpoints.     

The effects of drying on the structure and permeability of the wood of Abies grandis

Summary The effects of air-drying and solvent-drying on the sapwood of Abies grandis have been investigated by a new method for the determination of the size and number of conducting tracheid lumina and pit membrane pores which involves the measurement of gaseous permeability at various mean pressures. Both earlywood and latewood tracheids (83% of the total) were found to be conducting in solvent-dried wood, but in air-dried wood only latewood tracheids (32% of the total) were conducting. In solvent-dried wood there were on average 27,000 pit membrane pores per conducting tracheid compared with only 600 in air-dried wood. In both, the average pit membrane pore radius was about 0.1 m.Liquid permeabilities have been predicted from the calculated radii and numbers. The liquid permeability of solvent-dried wood was 31 times greater than that of air-dried wood in which the lumina were responsible for 13% of the total resistance to flow. The lumina were responsible for 39% of the resistance in solvent-dried wood and it is suggested that in first-formed earlywood the lumina may cause more than half the total resistance.A new method is described for the cleaning of direct carbon replicas of wood. In this the cellulose is removed by cellulase instead of sulphuric acid, and no wax backing is required. This provides much cleaner replicas. Electron micrographs have been obtained of both earlywood and latewood dried by the two methods.The authors wish to thank Mr. A. R. Sayers for preparing the computer programme used in this work, Dr. R. Ph. C. Johnson for his help and advice regarding the electron microscopy and Professors Matthews and Weatherley for their advice and encouragement.     

Effects of Nitrogen Fertilizer and Current Climate on Wood Properties of Corsican Pine (Pinus nigra var maritima (Ait.) Melv.)

Selected wood and cell characteristics were examined in incrementcores from two 46-year-old pines that had been fertilized withammonium sulphate 37, 38 and 39 years after planting. Fertilizationincreased the ring-width and greatly reduced the latewood percentand the bulk density of both early and late wood; the effectswere greatest shortly after the last application of fertilizer,but remained apparent for at least five further years. Thoughboth trees produced more early wood cells only one of the twoproduced more latewood. The average tracheid diameter was not changed, though its rangewithin the annual ring was increased. There were decreases intracheid wall-thickness and length, and in wall volume per tracheid.These changes were greatest in latewood, so that the differencebetween early and latewood was reduced, while the characteristicsof the earlywood were exaggerated. Resin canal radial (but nottangential) diameter and cross-sectional area increased, thoughnumber of canals per unit area of ring was unchanged. Correlations with temperature, insolation and rainfall in March-Juneand July-October suggest that (1) wood properties are influencedby the weather of both the current and the previous growingseasons; (2) the climatic optima for the fertilized and unfertilizedtrees are different and consequently (3) the weather influencesthe effect of fertilization on wood properties.     

Microfibril angle non-uniformities within normal and compression wood tracheids

The pattern and extent of variation of microfibril angle (MFA) in normal and compression tracheids of softwood were investigated by using confocal laser scanning microscopy technique. All measurements support the idea that the orientation of microfibrils in single wood tracheids is not uniform. MFA of the radial wall of earlywood tracheids was highly non-uniform and had an approximately circular form of arrangement around the bordered pits (inside the border). Between the bordered pits the measured MFAs were less than the other parts of the tracheid. In the latewood tracheids MFA was less variable. The average orientation of simple pits in the crossfield region was consistent with the mean MFA of the tracheids; however some of the measurements showed a highly variable arrangement in the areas between the simple pits. In many cases the local measured MFAs of compression wood tracheids agreed with the orientation of natural helical cavities of compression wood. Comparing the measured results in different growth rings showed that MFAs in juvenile wood are generally larger than in perfect wood.     

Variation Within Trees of Wood Anatomical Properties in Chinese-Fir Plantation and Their Relationship Modeling Equations

A comprehensive analysis on the variation pattern of early- and latewood tracheid morphological parameters along tree (Cunninghamia lanceolata Hook.) height, including length and width, wall thickness, tissue proportion, cell wall percentage, width of growth rings, and on the relationship among them are conducted. The results indicate an initially rapid and then gentle increase of tracheid length and width, thickness of the radial wall and tangential wall of tracheid, area percentage of tracheid from pith to outward, while S2 microfibril angle (Mfa) of tracheid, and rays percentage gradually decrease and then tend to be stable. The variation of all anatomical parameters but earlywood cell wall thickness shows no significance along tree height. The radial variation pattern of width of growth rings is characterized with initially slight decrease followed immediately by a rapid and then much more gentle increase from pith to outward. The delimitation age between juvenile and mature wood is 14-16 years. Com     

Variation of measured cross-sectional cell dimensions and calculated water vapor permeability across a single growth ring of spruce wood

A statistical study of the cell dimensions in a growth ring of spruce along the radial and tangential directions is performed. The data are used to study the variation of the cell vapor permeability in the growth ring. Studying cell rows within one growth ring, the frequency distributions of the cell wall thickness in the radial direction and of the lumen dimension in the tangential direction are found to be both unimodal. In contrast, the frequency distributions of these dimensions in the other directions are bimodal, where the different modes can be attributed to earlywood and latewood. Analysis of the bimodal distributions results in the determination of threshold values of cell wall thickness and the lumen dimension for earlywood and latewood tracheids. The cell dimensions are used to predict cell porosity and water vapor permeability distribution within a growth ring. The bimodal frequency distributions of the tangential cell wall thickness and the radial lumen dimension provide an explanation for the observed bimodal frequency distribution of the cell water vapor permeability both in radial and in tangential directions. Contrary to measured macroscopic vapor permeability results, the tracheid geometry results in lower cell vapor permeability in radial than in tangential direction. This confirms that rays play an important role in the vapor permeability of wood, as they can be considered as pathways for vapor transport in radial direction. The dataset analyzed in this paper leads to a set of parameters characterizing the earlywood and latewood cell dimensions. Such characterization can be used, for example, for producing synthetic data for computational modeling studies.     

Wood properties of trembling aspen and paper birch after 5 years of exposure to elevated concentrations of CO(2) and O(3)

We investigated the interactive effects of elevated concentrations of carbon dioxide ([CO(2)]) and ozone ([O(3)]) on radial growth, wood chemistry and structure of five 5-year-old trembling aspen (Populus tremuloides Michx.) clones and the wood chemistry of paper birch (Betula papyrifera Marsh.). Material for the study was collected from the Aspen FACE (free-air CO(2) enrichment) experiment in Rhinelander, WI, where the saplings had been exposed to four treatments: control, elevated [CO(2)] (560 ppm), elevated [O(3)] (1.5 x ambient) and their combination for five growing seasons. Wood properties of both species were altered in response to exposure to the treatments. In aspen, elevated [CO(2)] decreased uronic acids (constituents of, e.g., hemicellulose) and tended to increase stem diameter. In response to elevated [O(3)] exposure, acid-soluble lignin concentration decreased and vessel lumen diameter tended to decrease. Elevated [O(3)] increased the concentration of acetone-soluble extractives in paper birch, but tended to decrease the concentration of these compounds in aspen. In paper birch, elevated [CO(2)] decreased and elevated [O(3)] increased starch concentration. The responses of wood properties to 5 years of fumigation differed from those previously reported after 3 years of fumigation.