国产主要阔叶树材导管和纤维瘤状层的电镜观察和研究

对我国１８２种（４８科１３５属）阔叶树材导管和纤维壁的内表面进行扫描和透射电镜观察，其中５０种（隶１７科３２属）有瘤状层存在，其余不见或罕见。就这５０种木材的瘤状层有无及其形态和分布进行深入的观察与探讨。并对２种木材的超薄切片进行透射电镜观察和分析，认为瘤状物与次生壁的电子密度不同，说明两者化学成分不同。此外，还讨论了瘤状层的分布与穿孔板类型和在生长轮的位置关系。未发现瘤状层的出现和木质部进化趋势     

中国裸子植物木材管胞瘤状层的电镜观察

本文对中国裸子植物11科、41属、99种木材管胞瘤状层进行了系统观察。瘤状层的有无及形态特征是区分裸子植物材的重要标志。此外并对5种针叶树材在一个年轮内,瘤状层从早材到晚材大小、分布密度的变化做了观察;12种针叶树材的切片,用0.5％次氯酸钠溶液处理后,瘤状物减小、以至消失;在另6个树种的管胞内,观察到瘤状层被白腐菌或软腐菌溶解。     

Helical orientation of the microfibrils in tracheids,fibres and vessels

The helical winding direction of microfibrils in the S2 wall layer in the tracheids, fibres and vessel members of over 250 woody species, both indigenous and exotic, growing in New Zealand has been determined. A Z helix was observed in all the tracheids, fibres and narrower vessel members. The orientation in the wider vessel members could not always be determined with any certainty.     

Ultrastructural implications of gamma-irradiation of wood

Summary An attempt is made in this study to relate the gamma-irradiation induced degradation of wood samples to their lignin content and distribution in the cell wall. Samples of Douglas-fir and yellow-poplar were submitted to increasing doses of gamma-irradiation and subsequently extracted with a dilute NaOH solution or with DMSO, prior to SEM observation. Other samples were observed in TEM. The irradiation-extraction procedure degraded the hardwood more than the softwood. In both species, the middle lamella was more resistant than the secondary wall. The S3 layer in Douglas-fir and the warty layer in yellow-poplar appeared to be more resistant than the other secondary wall layers. Some difference was also observed in radiation stability between tracheids or fibres and ray cells. This procedure is suggested as a method for studying lignin distribution in the wood cell wall.This research was conducted as part of a thesis submitted by the first author in partial fulfilment of the requirements for the Master of Science degree at the State University of New York College of Environmental Science and Forestry, Syracuse, New York. The authors wish to thank Dr. John A. Meyer who carried out the irradiation procedure. The first author also whishes to express gratitude to the Belgian American Educational Foundation, Inc., The Fondation Francqui and Mister Charles Berolzheimer, Research Director of the California Cedar Products Company, for having provided financial support for this study     

Comparative study of morphological changes in hardwoods treated with the ionic liquid, 1-ethyl-3-methylimidazolium chloride

Three hardwoods of varying vessel arrangement were treated with the ionic liquid, 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), which can dissolve cellulose, to investigate its influence on wood tissue morphology. Characterization was carried out by light and scanning electron microscopy. The wood fibers of all species swelled significantly during [C2mim][Cl] treatment. The swelling behavior varied according to wood species and differed from other cell types such as ray parenchyma cells. Morphological changes of the pits also varied between wood species. Treatment with [C2mim][Cl] affects wood tissues differently depending on wood species and cell type. These differences are not due to the vessel arrangement and its presence, but possibly from the chemical component and the microfibril angle of various wood tissues.     

Distribution of lignin in normal and compression wood of Pinus taeda L.

Summary The distribution of lignin in normal and compression wood of loblolly pine (Pinus taeda L.) has been studied by the technique of lignin skeletonizing. Hydrolysis of the wood carbohydrates with hydrofluoric acid left normal wood tracheids with a uniform distribution of lignin in the S1 and S2 cell wall layers. However, the S3 region of both earlywood and latewood tracheids consistently retained a dense network of unhydrolyzable material throughout, perhaps lignin.Lignin content in compression wood averaged about 7% more than in normal wood and appears to be concentrated in the outer zone of the S2 layer. The inner S2 region, despite helical checking, is also heavily lignified. The S1 layer, although thicker than normal in compression wood tracheids, contains relatively little lignin.Ray cells, at least in normal wood, appear to be lignified to the same extent, if not more so in certain cases, than the longitudinal tracheids. Other locations where lignin may be concentrated include initial pit border regions and the membranes of bordered pits.This report is a detailed excerpt from the Ph. D. dissertation of R. A. P. Financial support provided by the College of Forestry at Syracuse University and the National Defense Education Act is hereby gratefully acknowledged.     

藤茎的导管分子研究

本文描述了棕榈科省藤属及黄藤属共24种藤茎的导管分子。毛鳞省藤(Calamus thysanolepis Hance)仅具单穿孔板,其余藤种均有单穿孔板和复穿孔板,但具复穿孔板导管分子的数量少,并且大部分存在于维管区外围。此外,观察到少数具复穿孔板的螺纹导管分子。自茎的外围向内,后生木质部导管分子的宽度增大;多数藤种的导管分子长度呈增大的趋势,部分藤种则相反,或无规律。     

Anatomy and lignin distribution of reaction wood in two Magnolia species

Summary Anatomical features of reaction wood formed in two Magnolia species, M. obovata Thunb. and M. kobus DC. which are considered to be among the primitive angiosperms, were observed. In addition, the distribution of guaiacyl and syringyl units of lignins in the cell walls of normal and reaction wood was examined using ultraviolet (UV)- and visible light (VL)- microspectrophotometry coupled with the Wiesner and M?ule reactions. The two Magnolia species formed a tension-like reaction wood without possessing the typical gelatinous layer (G-layer) on the upper side of the inclined stem or branch, in which a radial growth promotion occurred. Compared with the normal wood, the reaction wood had the following anatomical features: (1) the secondary walls of fiber tracheids lacked the S₃ layer, (2) the innermost layer of fiber-tracheid walls showed a small microfibril angle, a fact being similar to the orientation of the microfibril angle of the G-layer in tension wood, and (3) the amounts of lignin decreased in the cell walls of fiber tracheids, especially with great decrease in proportion of guaiacyl units in lignins. In addition, VL-microspectrophotometry coupled with the Wiesner and M?ule reactions adopted in the present study showed potential to estimate the lignin contents in the cell walls and the proportion of guaiacyl and syringyl units in lignins. Received: 15 July 1998     

纳米压痕技术测量管胞次生壁S2层的纵向弹性模量和硬度

重点研究和详细介绍了利用纳米压痕技术测试管胞次生壁S2 层纵向弹性模量以及硬度的实验技术 ,并测试了人工林杉木早晚材管胞S2 层的纵向弹性模量和硬度。结果表明 :杉木晚材管胞S2 层的平均纵向硬度为0 390GPa ,弹性模量的平均值为 1 4 84 4GPa ;早材管胞S2 层的硬度和模量则小于晚材 ,平均值分别为 0 30 6GPa和9 82 3GPa。     

Ultrastructure of pits inPinus banksiana lamb

Summary The cross-sectional view of pitting between various cell types inPinus banksiana Lamb. was studied at the ultrastructural level. Cell types inPinus banksiana include longitudinal tracheids, ray tracheids, ray parenchyma cells, buffer cells and epithelial cells. Two common characteristic features of bordered pit-pairs between longitudinal tracheids are an initial pit border and a thickened torus at the center of the pit membrane. The shape and size of the pit border and torus of bordered pit-pairs between two compression wood cells, and between the last-formed latewood longitudinal tracheid and first-formed earlywood longitudinal tracheid were different from those in the earlywood and latewood longitudinal tracheids. The pit border on the ray tracheid side varied in size and shape due to wall dentation. No initial pit border was found on the pit border of the ray tracheid side. The shape of bordered pit-pairs between two ray tracheids varied considerably due to irregularity of the dentate cell wall. The size of bordered pit-pairs in longitudinal tracheids was between 16 m to 20 m, which was twice the diameter of bordered pit-pairs in ray tracheids. Bordered pitpairs at the end wall of two ray tracheids appeared to be the smallest at 5 m, Pit aspiration occurred in the bordered pit-pairs with or without a torus. In the heartwood zone, some half-borders pit-pairs between tracheary and ray parenchyma cells showed an additional secondary wall on the ray parenchyma cell side. Plasmodesmata were found in the half-bordered pit-pairs as well in the simple pit-pairs. Blind pits were observed between a ray tracheid and a longitudinal tracheid. Bordered pit-pairs between two buffer cells were also observed. The possible functions of buffer cells were discussed.Use of transmission electron microscope provided by the Science Instrumentation Lab, Lakehead University and the technical assistance provided by Mr. A. MacKenzie, Director of Science Instrumentation Lab are gratefully appreciated     

Three-dimensional imaging of a sawn surface: a comparison of confocal microscopy,scanning electron microscopy,and light microscopy combined with serial sectioning

The three-dimensional structure of a transverse sawn wood surface was investigated using several methods, to compare techniques, and to study the types of deformation in tracheids at the saw cut. A sample of spruce sapwood was cut with a fret saw across the grain. The transverse sawn surface was imaged by confocal microscopy, field emission scanning electron microscopy (FESEM), and by light microscopy combined with serial sectioning and three-dimensional (3D) reconstruction. Both confocal microscopy and FESEM were restricted to visualising the cut surface of the wood. However, serial sectioning was able to reveal the internal structure below the cut surface providing more information on the types of cell deformation present. The wood structure was deformed to depths of more than 600 μm below the surface with twisting, crushing and tearing deformations. Near the outer surface, gaps were formed between groups of tracheids where the cell walls had been torn away to form saw dust. The deformation tended to form groups of tracheids that were twisted relative to each other. Latewood was less distorted, forming a dense solid surface compared to the highly fibrous earlywood.     

Long-term management impacts on carbon storage in Lake States forests

We examined carbon storage following 50+ years of forest management in two long-term silvicultural studies in red pine and northern hardwood ecosystems of North America’s Great Lakes region. The studies contrasted various thinning intensities (red pine) or selection cuttings, shelterwoods, and diameter-limit cuttings (northern hardwoods) to unmanaged controls of similar ages, providing a unique opportunity to evaluate long-term management impacts on carbon pools in two major North American forest types. Management resulted in total ecosystem carbon pools of 130-137 Mg ha⁻¹ in thinned red pine and 96-177 Mg ha⁻¹ in managed northern hardwoods compared to 195 Mg ha⁻¹ in unmanaged red pine and 224 Mg ha⁻¹ in unmanaged northern hardwoods. Managed stands had smaller tree and deadwood pools than unmanaged stands in both ecosystems, but management had limited impacts on understory, forest floor, and soil carbon pools. Total carbon storage and storage in individual pools varied little across thinning intensities in red pine. In northern hardwoods, selection cuttings stored more carbon than the diameter-limit treatment, and selection cuttings generally had larger tree carbon pools than the shelterwood or diameter-limit treatments. The proportion of total ecosystem carbon stored in mineral soil tended to increase with increasing treatment intensity in both ecosystems, while the proportion of total ecosystem carbon stored in the tree layer typically decreased with increasing treatment intensity. When carbon storage in harvested wood products was added to total ecosystem carbon, selection cuttings and unmanaged stands stored similar levels of carbon in northern hardwoods, but carbon storage in unmanaged stands was higher than that of thinned stands for red pine even after adding harvested wood product carbon to total ecosystem carbon. Our results indicate long-term management decreased on-site carbon storage in red pine and northern hardwood ecosystems, but thinning intensity had little impact on carbon storage in red pine while increasing management intensity greatly reduced carbon storage in northern hardwoods. These findings suggest thinning to produce different stand structures would have limited impacts on carbon storage in red pine, but selection cuttings likely offer the best carbon management options in northern hardwoods.     

Occurrence of decay-associated xylem suberization in a range of woody species

Suberization responses to naturally-occurring fungal colonization of living xylem tissues were detected in 30 of 37 woody species examined. These responses comprised the suberization of traumatic parenchyma tissues in compartmentalization wall 4 barrier zones laid down in the vicinity of fungally infected wounds, or the suberization of parenchyma cells, tyloses and vessel linings in reaction zone decay margins in fully differentiated sapwood. Additionally, in a few species, suberization of xylem fibres and tracheids was observed where juvenile xylem tissues, apparently still incompletely differentiated, had been exposed by wounding. These xylem suberization responses are considered to increase the decay resistance of the altered cells, and may protect the hydraulic integrity of adjacent tissue, thus contributing to the antimicrobial defence of the living sapwood.     

Maximum effective vessel diameters of hardwoods

Summary Measurements of the gas pressure required to displace water and allow gas bubbles to start continuously passing through the void structure of hardwood cross sections varying in thickness from 0.1 ... 10.0 cm have been used to calculate the maximum effective opening diameters. These diameters decrease with an increase in the thickness of the cross sections, as is the case for softwoods. Extrapolation of diameter—thickness plots to zero thickness gives the maximum vessel diameters, which agree well with microscopically determined values. The relatively small decrease in the maximum effective opening diameters with increasing thickness of the cross sections for most of the sapwood samples tested is due to irregularities in the vessel diameters and presence of perforation plates at the ends of the vessel segments. The decrease in the maximum effective opening diameter with an increase in the thickness of the cross sections is greater for the heartwood than for the sapwood. The ratio of the sapwood to the heartwood values tends to become constant between cross section thicknesses of 2.5 and 5.0 cm. This ratio was small for tyloses free northern red oak but appreciable for the hardwoods containing tyloses in the heartwood. Air drying followed by oven drying and resaturating of the specimens with water caused only small variable changes in the maximum effective opening diameters that were within the range of experimental accuracy of the measurements (approximately 5%).Paper No. 3616 of the Journal Series of North Carolina State University Agricultural Experiment Station, Raleigh, N. C.     

针叶树木中矿质元素的分布

综述了矿质元素在针叶树干内的径向、轴向和细胞壁内的分布特点;影响矿质元素在树干内分布的主要因素。评述了以树木中矿质元素的分布特征进行树木分类的可行性,以及树干年轮间元素的变化值作为评价环境年代变迁指标的有效性。并对今后的研究方向提出了建议。     

Influence of accessory substances,wood density and interlocked grain on the compressive properties of hardwoods

Wood samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected to perform moisture sorption tests associated with parallel-to-grain and tangential compression tests using a multiple step procedure at 25°C. Cold-water and hot-water extractives, sequential cyclohexane (CYC), acetone (ACE) and methanol (MET) extracts, ash content (ASH), wood density and interlocked grain (IG) were evaluated on matched samples too. Wood density corrected for the accessory substances was by far the major factor positively affecting the compressive properties of tropical hardwoods. The total amount of accessory substances is required in order to establish better relationships between physico–mechanical properties and density of tropical hardwoods. For a given wood density, the ultimate stress in parallel-to-grain compression was higher in tropical hardwoods than in temperate hardwoods. However, the compliance coefficients for both types of woods were quite similar. Sequential extraction with organic solvents was the most suitable method for evaluating the effect of extractives on compressive properties of tropical hardwoods. The CYC and ACE fractions did not contribute to variation in these mechanical properties. The substances dissolved in MET affected positively the compliance coefficient s ₁₁ in parallel-to-grain compression and negatively the compliance coefficient s ₃₃ in tangential compression. The IG decreased the compliance coefficient s ₁₁ but also decreased the ultimate stress in parallel-to-grain compression. Finally, variations in compressive properties that were due to changes in equilibrium moisture content (EMC) were clearly influenced by wood density; denser woods were more sensitive to changes in EMC than lighter woods.     

Observations of trabeculae in New Zealand hardwoods

Summary During a survey on the anatomy of New Zealand native woods, trabeculae were observed in the xylem cells of 6 hardwood species endemic to New Zealand. They were not found in a further 216 species. In some species they were observed only in the vessel members while in others they occurred in the vessel members, fibres and axial parenchyma cells. Their diameter is proportional to the thickness of the host cell wall. The similarites and differences between these trabeculae and those described as occurring in softwoods and other hardwoods are discussed. No explanation is proposed for their origin.We are indebted to the Conservators of Forests for Nelson and Westland, and to the Egmont, Abel Tasman, Urewera and Arthur's Pass National Park Boards for permission to collect wood samples; and also to Mr R. R. Exley, Physics and Engineering Laboratory D.S.I.R. for technical assistance.     

Bond strength of end-grain joints and its dependence on surface roughness and adhesive spread

The effect of different machining processes on surface roughness and on adhesive tensile strength of end-grain-bonded spruce wood specimens was studied. Surfaces that had been cut with two different circular saws containing 48 and 96 teeth were compared with those that had been further processed by smoothing with a microtome, machine planing, or sanding. Two different adhesives and two different spreading quantities were used to join the test specimens by their end-grain surfaces. Increasing tensile strength of the bonded specimens was observed with increased surface roughness, which was ascribed to an enlarged bonding area in the case of circular-sawn samples with a rough surface. On the other hand, more pronounced starving of the bond line and thus decreased bond strength was observed in the more open cells of the smoothed end-grain surfaces. A positive effect regarding tensile strength was further observed with increased spreading quantity of the adhesives. Machining was found to particularly affect earlywood tracheids, whereas surface roughness of latewood tracheids was comparable for the differently treated end-grain surfaces     

Haustorial morphology of Cronartium conigenum in naturally infected cones of three Pinus species from Guatemala1

Haustorial morphology of the cone-rust pathogen, C. conigenum, was investigated among naturally infected female strobili of three Guatemalan pines, P. maximinoi, P. pseudostrobus, and P. oocarpa. Among the three pine species, haustorial shapes and sizes were more variable in P. maximinoi and P. oocarpa than in P. pseudostrobus. The haustorial shapes and sizes were more variable in parenchyma cells of the cortex, xylem, and pith than in the cells in the phloem, xylem rays, and tracheids. The haustoria were also present in larger numbers in the parenchyma cells of the cortex, xylem, and pith than in phloem parenchyma cells and tracheids. In living cells, the tips of some haustoria were appressed to the host nuclei.     

松材线虫病致病机理的研究进展

该文对松材线虫病的致病机制的研究进行了概述。目前对松材线虫病的病原有两种看法，一种认为松材线虫是惟一病原，另一种认为病原为松材线虫和细菌两种生物。对于松材线虫的致病机理，目前存在3种观点。第1种观点认为松材线虫的酶使松树薄壁细胞的细胞壁和细胞膜遭到破坏，树脂不正常地从树脂道中渗漏并扩散到相邻的管胞中，使水分输导受阻，导致萎蔫。第2种观点认为松树感染了松材线虫后，木质部内挥发性萜烯类物质的含量增加，这些物质进入管胞在管胞中形成空洞，致使水分输导受阻。第3种观点认为松树感染松材线虫后，体内产生有毒物质，这些物质使松树萎蔫。