Polysaccharides in some industrially important softwood species

The content and composition of carbohydrates comprising polysaccharides in sapwood and heartwood of 12 industrially important pulpwood species were analysed. The polysaccharide content was between 60% and 80% (w/w) for all species, with cellulose as the predominant polysaccharide type. The carbohydrate composition suggested that the main non-cellulose polysaccharides were galactoglucomannans, except in Larix heartwood, where arabinogalactans were predominant, while the content of xylans were in the same range as the mannans in Pinus resinosa heartwood and Thuja occidentalis heartwood and sapwood. Pectins, i.e. polygalacturonic acids, were the main acidic polysaccharides in all species. The amount and composition of water-soluble carbohydrates from ground wood samples were also analysed, since these are important in mechanical pulping and as a possible source of bioactive polymers. The main polysaccharides released from the spruce species were mannans, together with starch from sapwood. Especially Abies balsamea stemwood, but also Abies sibirica heartwood, released considerable amounts of pectins, suggesting that fir species may release more troublesome anionic polysaccharides than spruce species. Heartwood of Larix lariciana, Larix decidua, Pinus banksiana, and Pinus resinosa released considerable amounts of acidic arabinogalactans. Thuja occidentalis released mainly arabinogalactans and pectins. Pseudotsuga menziesii heartwood released a large amount of arabinogalactans.     

Characterization of strength properties of branchwood and stemwood of some tropical hardwood species

The mechanical strength properties of the branchwood of Aningeria robusta and Terminalia ivorensis with diameters ranging from 10 to 25 cm were examined to determine the suitability of branchwood as raw material for downstream processing. The study precisely assessed the static bending strengths, compression strengths and shear strengths parallel to the grain of the branchwood and stemwood of T. ivorensis and A. robusta. It was observed that under static bending, the overall (sapwood and heartwood combined) modulus of rupture and modulus of elasticity of the branchwood of A. robusta and T. ivorensis were lower than that of their corresponding stemwood. The results further show that the overall compression and shear strengths parallel to the grain of the branchwood of A. robusta and T. ivorensis were higher than that of their corresponding stemwood. Under static bending, compression parallel to the grain, and shear parallel to the grain, the experimental results indicate that the sapwood of the branchwood from both T. ivorensis and A. robusta had lower strength values than that of their corresponding heartwood. Similar results were recorded for the stemwood of T. ivorensis where the heartwood had higher strength values than the sapwood. However, in the case of the stemwood of A. robusta, the sapwood had higher strength values than the corresponding heartwood.     

Effect of heat treatment intensity on some conferred properties of different European softwood and hardwood species

Effect of heat treatment intensity on some conferred properties like elemental composition, durability, anti-swelling efficiency (ASE) and equilibrium moisture content (EMC) of different European softwood and hardwood species subjected to mild pyrolysis at 230 °C under nitrogen for different durations has been investigated. Independently of the wood species studied, elemental composition is strongly correlated with the mass losses due to thermal degradations which are directly connected to treatment intensity (duration). In all cases, an important increase in the carbon content associated with a decrease in the oxygen content was observed. Heat-treated specimens were exposed to several brown rot fungi, and the weight losses due to fungal degradation were determined after 16 weeks, while effect of wood extractives before and after thermal treatment was investigated on mycelium growth. ASE and EMC were also evaluated. Results indicated important correlations between treatment intensity and all of the wood conferred properties like its elemental composition, durability, ASE or EMC. These results clearly indicated that chemical modifications of wood cell wall polymers are directly responsible for wood decay durability improvement, but also for its improved dimensional stability as well as its reduced capability for water adsorption. All these modifications of wood properties appeared simultaneously and progressively with the increase in treatment intensity depending on treatment duration. At the same time, effect of extractives generated during thermal treatment on Poria placenta growth indicated that these latter ones have no beneficial effect on wood durability.     

Liquid penetration in different cells of two hardwood species

Two experimental techniques were used to test the water permeability of two Korean hardwood species: diffuse porous Populus tomentiglandulosa T. Lee (eunsasi poplar) and ring porous white oak, Quercus serrata Thunb (konara oak). The first technique measured the void volume filled at different moisture content (MC) levels. Samples were treated with water via a schedule of full-cell impregnation. A significant relation between MC and permeability (the fractional void volume) was found. A reduction in liquid permeability was observed at MC above the fiber saturation point (FSP), whereas the opposite result was observed at MC below FSP due to the effect of the voids available in the wood. However, the differences of increased permeability from MC level 20% to 0% were found satistically the same in either wood species. The second technique measured the speed of liquid penetration in vessels, fibers, and rays with no application of external pressure. In this method, liquid flow was captured via video and the penetration speed was measured. Vessels, fibers, and rays in poplar were found to be more permeable than those in oak. Different anatomical factors such as cell diameter, cell length, pit number, pit aperture area, and thickness of the pit membrane seemed to be responsible for the variation of liquid flow rate in different cells of the two hardwood species.     

Dielectric properties of hardwood species at microwave frequencies

Dielectric measurements at 9.8GHz and 2.45GHz were made for the three hardwoods Euramerican hybrid poplar, alder, and oriental beech. The method used was based on Von Hippels transmission line method. The measurements were carried out at room temperature of 20°–24°C. The dielectric properties of the wood species were determined for the three principal structural directions at six different moisture conditions, covering the range of 0% to 28% moisture content. Results indicated that the behavior of all wood species studied is quantitatively similar. In general, the dielectric properties increase within the range studied with rising moisture content. The grain direction of the wood also plays a significant role.     

Estimating biomass and macronutrient content of some commercially important plantation species in South Africa

The removal of biomass, in any combination of stemwood, bark or branch harvesting, can cause a significant increase in nutrient loss from commercial timber plantations. Ensuring long-term site productivity of forest plantations is a key issue for forestry management. Managers need to secure a continued supply of tree biomass components, while understanding the impact of various harvesting operations on plantation nutrient reserves. It is imperative to quantify the biomass and nutrient stocks and their removal during silvicultural operations, such as harvesting, burning and various forms of site preparation. At present, there are no simple methods to estimate inherent site nutrient reserves, or nutrient gains through processes such as atmospheric deposition or rock weathering, or the quantities of nutrients lost through silvicultural operations (harvesting, burning and site preparation). The aim of this work was to construct simple multipliers that can be used in conjunction with plantation timber volumes to estimate stem, branch and bark biomass and nutrient contents. The multipliers were developed from data existing for Eucalyptus spp., Pinus patula and Acacia mearnsii stands throughout the summer rainfall region of South Africa and Swaziland. Due to limited data unique nutrient multipliers were not developed for each productivity range and the multipliers were assumed to be consistent across all productivity ranges. The ratios may underestimate on fertile sites where luxury consumption of nutrients may occur and not accurately predict where stand management practices have altered wood density, allometry or canopy architecture. Although genus and species impacted on the quantity of nutrients held in the plantation biomass, productivity and harvesting intensity were the biggest driver of nutrient removal. Although the multipliers developed here have value in creating a general estimate of nutrient content they are from a limited dataset and need to be expanded upon across species, site and age ranges before being able to precisely estimate nutrient contents. Although harvesting is a major component of nutrient export, natural additions and losses of nutrients, and site nutrient reserves need to be known in order to gain a complete understanding of the impact of nutrient loss on site nutrient reserves.     

23种广东常见阔叶树材的耐磨性质

本文报导23种广东常见阔叶树材的耐磨性试验结果,并对耐磨性与木材密度、硬度的关系及木材耐磨性各向异性问题作了讨论。     

Comparative water relations of three successional hardwood species in central Wisconsin

Water relations of co-occurring understory saplings of Quercus ellipsoidalis E.J. Hill, an early successional, xeric species, Populus tremuloides Michx., an early successional, mesic species, and Acer rubrum L., a late successional species that occurs on both wet and dry sites, were evaluated on four dates during the 1986 growing season. The understory was characterized by high soil water content, low irradiance and low vapor pressure deficit throughout the growing season. Stomatal conductance and calculated transpiration flux were lowest for A. rubrum and highest for P. tremuloides and Q. ellipsoidalis. Except early in the growing season, leaf water potentials were lower in P. tremuloides than in the other species. Populus tremuloides had the highest bulk modulus of elasticity, Q. ellipsoidalis the lowest. Over the growing season, Populus tremuloides and Q. ellipsoidalis, but not A. rubrum, exhibited a decrease in osmotic potential at both full and zero turgor. Of the three species, Populus tremuloides exhibited the sharpest decrease in leaf water potential and turgor pressure with decreasing relative water content.     

Tree species exhibit complex patterns of distribution in bottomland hardwood forests

?Context

Understanding tree interactions requires an insight into their spatial distribution.

?Aims

We looked for presence and extent of tree intraspecific spatial point pattern (random, aggregated, or overdispersed) and interspecific spatial point pattern (independent, aggregated, or segregated).

?Methods

We established twelve 0.64-ha plots in natural bottomland hardwood stands in the southeastern USA.

?Results

Spatial point pattern analyses (Ripley’s K, L, and L ₁₂) indicated that, when species were combined, trees were frequently aggregated and less commonly overdispersed. Plots with larger trees were more likely to exhibit overdispersion, confirming a shift to this pattern as trees grow. The intraspecific pattern of cherrybark oak and water oak was either aggregated or random. Sweetgum was aggregated on all plots and always at smaller distances (less than 5 m) than the two oak species. Intraspecific overdispersion was very rare. Interspecific segregation among the two oak species was more commonly observed (six plots) than aggregation (one plot). Cherrybark oak and sweetgum were segregated at some scale on seven of the 12 plots and aggregated on only two plots.

?Conclusion

The results from the analyses suggest that strong interspecific competition may result in segregation of trees from different species, while weaker intraspecific competition may lead to aggregations of conspecifics.     

A new methodology to select hardwood species for wooden products

Abstract

In general, only a few wooden species are used or even considered for any given wooden product, even though hundreds of alternative wood species are available. In many cases, the reason for this is tradition rather than availability, technical or aesthetic considerations and it can result in endangered species being used to an unnecessarily high degree. The purpose of this study was to develop a structured, quantifiable, and easy-to-use methodology to identify suitable hardwood species for a specific product. The methodology combines processes based on quality function deployment and multivariate data analysis in a three-step workflow, and takes different criteria into consideration. To verify the methodology, it was applied to an example product: an electric guitar. It was shown that the methodology was easy to use and provided useful and quantifiable results. Expansion of the underlying wood species data-set will be necessary to improve the performance in the future.     

五种福建阔叶树材的干燥特性

本文论述了利用百度试验法,查明福建五种阔叶树材的干燥特性,以进一步制定合理的干燥工艺。实验结果表明:这五种阔叶树材干燥特性差异显著,其中椆木干燥缺陷严重,干燥速度缓慢;润楠及枫香干燥缺陷中等;蓝果树及荷木干燥缺陷程度最轻,枫香干燥速度最快。     

Stiffness moduli of various softwood and hardwood species determined with ultrasound

Abstract

Comprehensive data sets of the elastic constants are available for only a few European wood species. The goal of this study was to provide stiffnesses for the principal directions and planes for further selected European softwoods and hardwoods, to extend the currently existing data sets. For this purpose, a dynamic technique was chosen: the moduli were estimated on the basis of sound velocity and density measurements. The collected data may be helpful for specialists in the relevant research and practical fields, particularly when stresses and strains of structural elements have to be calculated using modelling approaches.     

Effects of forest management on structural features important for biodiversity in mixed-age hardwood forests in Australia's subtropics

The contiguous forest landscapes of the Brigalow Belt Bioregion in Australia's subtropics, known as ‘the western hardwood forests’ are thought to be important for biodiversity conservation through the provision of continuous habitat features in an otherwise extensively cleared region. However, these forests have a long management history, as they are also important for timber production and stock grazing. Knowledge of the effect of these and other disturbances on the distribution and abundance of key structural or habitat features are limited and forest management activities thus continue uninformed. To address this knowledge gap, we investigated the effects of prescribed and non-prescribed disturbances on the distribution and abundance of six key habitat features (live and dead trees with hollows, large mature live trees, shrub abundance, downed coarse woody debris and litter cover) at 120 sites located in spotted gum Corymbia citriodora dominant forests within the western hardwoods.     

Effect of the lateral growth rate on wood properties in fast-growing hardwood species

We investigated the feasibility of using several fast-growing tropical or subtropical hardwood species for timber production by measuring key wood qualities in relationship to the high rates of lateral growth. The trees tested were sampled from even-aged plantations of Acacia mangium, A. auriculiformis, hybrid Acacia (A. mangium × A. auriculiformis), Eucalyptus grandis, E. globulus, and Paraserianthes falcataria (Solomon and Java origin) that had already reached commercial harvesting age. The released strain of the surface growth stress (RS), xylem density (XD), microfibril angle (MFA), and fiber length (FL) were measured at the outermost part of the xylem at breast height in each tree. Results were then compared to the lateral growth rate (radius/age) at breast height, which provides a relative indicator of the amount of tree growth per year. Our findings indicated that RS was constant, regardless of lateral growth rate in each species. Similar results were observed for XD, MFA, and FL, with a few exceptions, suggesting that high growth rates do not intrinsically affect the wood properties of fast-growing tropical or subtropical species that have reached harvesting age. However, special attention must be paid to patterns of xylem maturation when developing plantations of such species.     

Polysaccharides in cones of eleven coniferous species growing in Turkey

Composition of polysaccharides in the cones of conifer species growing in Turkey was studied. The content of polysaccharides was between 39 and 57% (w/w). The total amount of polysaccharides was generally higher in pine species. Polyoses were the predominant polysaccharides. The percentage of polyoses was between 23.3 and 33.9% (w/w). The main units of polyoses were mannose and galactose, while in some species xylose was the other important sugar unit. Between 1 and 6.7% of the polyoses were soluble in hot water. Polyoses were more readily dissolved from fir species than from other species. Galactoglucomannan was dissolved from all cones. Contrary to wood, the content of cellulose was only between 13 and 27.5% (w/w) in cones.     

Production physiology of three fast-growing hardwood species along a soil resource gradient

We determined how specific leaf area (SLA), specific leaf nitrogen (SLN), leaf area index (LAI), light-saturated photosynthesis (Amax) and aboveground net primary productivity (ANPP) of three commercially important hardwood species, eastern cottonwood (Populus deltoides Bartr.), American sycamore (Platanus occidentalis L.) and cherrybark oak (Quercus falcata var.pagodafolia Ell.), vary across a soil resource gradient. Five treatments were applied in a randomized block design (control, irrigation only (IRR), and irrigation plus fertilization with 56, 112 or 224 kg N ha-1 year-1 (N56, N112 and N224)) with four replications per species. When trees were 6 years old, Amax, SLA, SLN, LAI and ANPP were quantified during peak leaf production within a single growing season. In all species, Amax for sun leaves was significantly higher than for shade leaves (34, 32 and 29 micromol m2 s-1 versus 27, 23 and 23 micromol m2 s-1 for cottonwood, cherrybark oak and sycamore sun and shade leaves, respectively) and tended to plateau in the N112 treatment. The SLA was significantly lower in sun than in shade leaves and reached a plateau in IRR-treated cottonwood and sycamore, and in N56-treated oak. Values of SLN peaked in the N122 treatment for cottonwood sun leaves (1.73 g N m2) and in the N56 treatment for sycamore and oak (1.54 and 1.90 g N m2, respectively). In sun and shade leaves of all species, Amax increased with increasing SLN. Cherrybark oak LAI reached a plateau across the resource gradient in the N56 treatment, whereas cottonwood and sycamore LAI reached a plateau in the IRR treatment. All species exhibited significant curvilinear relationships between canopy Amax and ANPP. These findings indicate that nutrients and water regulate leaf-level traits such as SLA and SLN, which in turn influence LAI and canopy photosynthesis, thereby affecting ANPP at the tree and stand levels.     

Extraction and analysis of the tangential arrangement of cambial cells in Japanese hardwood species

Arrangement of the cambium and marginal zone of xylem were illustrated by drawing the outlines of fusi-form cells and tissue on serial tangential sections inZelkova serrata andRobinia pseudoacacia with storied cambium and inAlbizia julibrissin with non-storied cambium. The comparison of cambium drawings with parenchyma drawings revealed that the lengths and arrangement of parenchyma strands correspond closely with those of corresponding fusiform initials in all three species with storied or non-storied cambium. Based on this result, we deduced the correlation between length and variation of length and arrangement of the fusiform initials in 20 species of Japanese hardwoods using parenchyma drawings instead of cambium drawings. The species with a smaller variation of length tend to exhibit a storied arrangement regardless of the length of the fusiform initial. Thus, it is suggested that the variation of the length of the fusiform initial has more influence than the length itself on the development of the storied arrangement.     

Target species identity is more important than neighbor species identity

This study investigates how the ability to overtop other saplings and the ability to capture most of the incident light together determine interspecific competition in young and dense self-thinning stands. To this end we measured crown positions and stratification, and quantified the effect of total foliage mass and foliage mass density of neighboring trees on the relative crown depth (RCD) of target trees. Field measurements were done on naturally established saplings in two large forest gaps of different age (5- and 15-year-old) in The Netherlands, and consisting of four species differing in shade tolerance.     

Susceptibility of Corymbia species and hybrids to arthropod herbivory inAustralian subtropical hardwood plantations

Corymbia hybrids are becoming significant plantation varieties in subtropical and tropical Australian plantation forestry. Although primarily developed for disease resistance and amenability to clonal propagation, they have also proven to have good growth rates and site plasticity. Here we examined the susceptibility of pure Corymbia species and hybrids to pest attack. Three trial sites containing C. citriodora subsp. variegata, C. torelliana, and the hybrids C. torelliana × C. citriodora subsp. variegata, C. torelliana × C. citriodora subsp. citriodora and C. torelliana × C. henryi were assessed for pest identity, incidence and severity. Pests caused about three-quarters of the visible crown damage to trees in these trials. At the site that had the most arthropod damage, hybrid trees had higher damage scores and higher growth scores (height, diameter at breast height over bark, and volume) than pure species. Site was more important than taxon in explaining damage scores, and taxa performed differently for most traits between sites. Tree growth was negatively correlated with general crown damage, while arthropod damage alone showed no significant relationship with growth. Our results highlight the importance of establishing taxa trials across a range of sites when selecting for pest resistance.     

Maturation property of fast-growing hardwood plantation species: A view of fiber length

The development of human civilization has caused many problems, among them increases in atmospheric CO₂ and shortage of fossil fuel resources. Fast-growing tree species can help solve these problems. Short rotations cause concern that fast-growing species contain a high proportion of juvenile wood, thus limiting their use. To use fast-growing species for timber, this concern must be addressed.