南方铁杉扦插繁殖技术

南方铁杉是我国特有的珍稀植物,因自然繁殖困难而处于濒临灭绝的程度。通过对南方铁杉扦插繁殖的关键技术进行研究,总结不同扦插基质、不同激素浓度和不同枝条年龄对扦插成活率的影响。结果分析表明:以100%黄心土+2年生枝条+ABT1号200×10-6配比处理的扦插效果最好。南方铁杉扦插成活率达75%以上。     

长苞铁杉群落结构特征研究

长苞铁杉属于珍稀濒危植物，被列为国家Ⅲ级保护植物。在样地调查材料的基础上，对福建省天宝岩自然保护区珍稀植物长苞铁杉群落结构、群落数量特征、种群动态进行了深入分析与研究。并对长苞铁杉濒危机制及保护措施进行了探讨，为长苞铁杉林的保护提供了理论依据。     

云南铁杉干燥过程中变色的控制

云南铁杉在干燥过程中的变色问题是困扰许多木业企业的一个技术难题。笔者通过近几年的研究和实践 ,从其木材组分入手 ,分析了在干燥过程中云南铁杉变色的原因 ,制定了减轻变色程度的干燥工艺措施 ,使铁杉干燥过程中的变色率降至 10 %以内 ,其质量达到国标规定相应的技术指标     

长苞铁杉人工促进幼苗更新技术研究

本文研究了上层木清除和凋落物清除等措施对长苞铁杉幼苗更新的影响,结果表明:人工形成的中等大小以上的林中空地和凋落物清除有利于长苞铁杉幼苗的生长和存活。     

福建光泽南方铁杉群落植物组成与多样性分析

采用样地调查法研究了福建光泽香炉山南方铁杉天然林群落植物组成与多样性。结果表明:光泽南方铁杉天然林群落(2000 m2)共有维管束植物27科40属52种。南方铁杉群落乔木层常绿树种占据优势,而灌木层常绿树种占据压倒性优势,说明常绿树种幼苗幼树耐阴性比落叶树种强,从而在林下低光照环境下具有更强的竞争能力。南方铁杉群落的乔木和灌木层发达,而草本层发育差,物种数与群落多样性指数均为灌木层>乔木层>层外植物>草本层;而均匀度则多为层外植物>灌木层>乔木层>草本层。南方铁杉种群幼苗幼树数量较多(2151株.hm-2),但小树数量极少(24株.hm-2),有一定数量的中树和大树(405株.hm-2)。南方铁杉幼苗幼树耐阴性差,难以与耐阴性强的常绿乔灌木树种竞争,这可能是南方铁杉濒危的原因之一。     

上犹县五指峰长苞铁杉林及其群落分析

长苞铁杉是我国特有的珍贵稀有树种,在赣南分布范围较窄,资源稀少。通过对上犹县境内五指峰长苞铁杉林的调查,分析其群落结构特征,对保护和发掘这一古老物种提出建议。     

林火干扰对长苞铁杉更新的影响

通过模拟实验和样地调查研究了林火干扰对长苞铁杉更新的影响,结果表明:长苞铁杉可以在森林火灾迹地中完成其生活史.长苞铁杉在模拟林火干扰样地的幼苗发生率为13%,在人工刈割杂草后样地为10.5%,而在对照组样地为0,杂草的遮荫作用对长苞铁杉幼苗的发生不利.经过一个完整生长季的生长,模拟林火干扰样地内幼苗存活率为68.1%,...     

无量山国家级自然保护区云南铁杉居群的特征研究

采用面积调查与抽样调查相结合的方法,对无量山国家级自然保护区云南铁杉的居群分布及结构动态等特征进行了研究。结果表明,无量山国家级自然保护区共记录到20个云南铁杉居群,面积2497．1hm2;居群的平均海拔分布为2560—2880m;居群的空间分布格局为聚集分布;胸径5em以上的立木分布密度为203．2棵／hm2,立木平均胸径为40．9cm;绝大多数立木的高度在15—40m之间;云南铁杉居群属于下降型居群。研究结果对云南铁杉的保护和利用具有重要的参考意义。     

加拿大铁杉扦插育苗技术

以加拿大铁杉的嫩枝、硬枝为繁殖材料,对扦插的基质、处理模式和环境控制进行筛选研究,确定出适宜加拿大铁杉嫩、硬枝扦插的条件。硬枝扦插分前期温室人工和后期全光自动喷雾两个阶段,嫩枝扦插分前期全光自动喷雾和后期温室越冬两阶段。适宜加拿大铁杉嫩枝扦插因素配比为:中上部穗条+珍珠岩+300mg/L1号ABT生根粉溶液,当年生根率达28.5%,竖年春生根率可达69.2%。适宜硬枝扦插因素配比为:中部穗条+沙∶珍为1∶2的基质+500mg/L1号ABT生根粉溶液,当年生根率达47.6%。     

长苞铁杉育苗技术研究

采集清流县大丰山长苞铁杉当年生、自然掉落的饱满种子进行育苗试验.结果表明:长苞铁杉育苗在50％日照条件下种子萌发率和幼苗成活率最高,幼株生物量最高,幼株生长最快,整个生命期生长最好;菌根接种对提高长苞铁杉种子萌发率没有明显的作用,但是菌根土育苗能显著提高幼苗的成活率,能极大提高幼苗生长量.     

The cellular distribution of lignans in Tsuga heterophylla wood

Summary Western hemlock heartwood contains patches of tracheids with large amounts of cellular inclusions. Microscopic and chemical examination of the wood showed several types of deposits containing the lignans matairesinol, hydroxymatairesinol and conidendrin. The deposits, which were often relatively pure individual lignans, frequently assumed different physical forms and chemical composition. A check in the wood contained three distinct forms of deposits each of which was a different lignan. Rays contained deposits physically similar to those in adjacent tracheids but, while lignans were present in the tracheids, they were not detected in the rays. Lignans lined tracheid walls as surface films and often encrusted the bordered pits. The amount of lignans in the wood was not related to wet wood zones although surface films and pit encrustations should have an influence on physical properties. The location and physical nature of lignan deposits in western hemlock heartwood indicates their biosynthesis has probably taken place at the heartwood periphery in the vicinity of the half-bordered pit.Presented at the International Wood Chemistry Symposium, Seattle, U. S. A. September 1969.Requests for reprints should be sent to W. E. Hillis. We thank Miss J. Barratt for assistance with part of this work and Mr. C. J. Kozlik for collecting wood samples.     

The influence of thermal-hydro-mechanical processing on chemical characterization of Tsuga heterophylla

Viscoelastic thermal compression (VTC) is a type of thermal-hydro-mechanical (THM) processing that requires only a short processing time. THM processing causes some chemical transformations, the nature and extent of hydro-thermolysis depends on the special treatment conditions and the chemical nature of wood species. In the present study, the chemical transformations of the cell wall components and wood extractives during VTC treatment were investigated, and correlation between chemical characterizations and observed property changes was analyzed. For this purpose, the content of extractives and pH values were determined, and FTIR analysis was performed on extractable substances, extract-free wood, holocellulose, α-cellulose and lignin. Two temperatures and two steam exposure times were adopted to determine the influence of processing conditions on chemical characterization of Tsuga heterophylla. The results revealed that THM treatment caused a series of chemical reactions in extractives. Treatment temperature and conditioning time have significant influence on chemical changes of extractives. For all of the VTC treatments used in this study, no significant changes occurred in the lignin and α-cellulose components. The only significant chemical changes occurred in the hemicelluloses, which were primarily reduction of carbonyl and acetyl functional groups. This study also confirmed that the chemical transformation of wood correlates with property changes of VTC wood.     

Size effect on longitudinal MOE of microtomed wood sections and relevant theoretical explanation

It has been repeatedly observed that the mechanical properties of microtomed wood sections are significantly lower than those of samples of normal size, but few investigations have been conducted to deal with this topic, especially based on theoretical approaches. We measured the longitudinal MOE of Chinese fir on microtomed sections ranging in thickness from 70 to 200 μm and compared these with the values of samples of normal size. The results indicate that the MOE of microtomed wood sections increases with thickness from 70 to 200 μm, but is significantly less than that of normal samples. A size effect coefficient of 2.63 is inferred based on statistical data for samples of normal size and 200 μm thick microtomed sections. Finally, an explanation based on a complete shear restraint model of cell walls and a single fiber multi-ply model is proposed for the size effect on stiffness of microtomed wood sections.     

Physical and mechanical properties and colour changes of fast-growing Gympie messmate wood subjected to two-step steam-heat treatments

This study aimed to evaluate physical and mechanical properties and colour changes of fast-growing Gympie messmate wood subjected to two-step steam-heat treatments. To achieve this, Gympie messmate wood was thermally treated under different conditions. Combined steam (127°C and ～0,1471 MPa) and heat treatments in an oven (180–240°C for 4 hours) were performed. Physical and mechanical properties were evaluated by weight loss, equilibrium moisture content, specific gravity, volumetric and linear swelling and static bending tests, while colour changes were studied using CIEL*a*b* technique. The main findings showed that the steam pre-treatment in autoclave influenced most of the technological properties evaluated, mainly for heat treatments performed in low temperatures (180–200°C). The most significant changes after thermal treatments were observed for dimensional stability, which increased as a function of temperature of treatment. On the other hand, mechanical strength of thermally modified wood was significantly affected, while stiffness did not change. Colour modifications due to the application of two-step steam-heat treatments confirm the possibility to using these samples for aesthetic purposes.     

美国木桥近期研究综述

为进一步开发木材在工程材料中的应用，本文从木桥的系统进展及规划设计、木材设计特性、木材防腐、用于运输系统中的木结构、木桥检测及修复、木桥设计规范及计算机辅助设计６个领域综述了美国木桥近期研究状况及进展     

Differences in wood properties between juvenile wood and mature wood in 10 species grown in China

 This study examined the intrinsic differences in various wood properties between juvenile wood and mature wood in 10 major reforestation species in China. Comparisons between juvenile wood and mature wood were made in both plantation- and naturally-grown trees. Considerable differences in most wood properties were found both between plantation-grown juvenile wood and mature wood, and between naturally-grown juvenile wood and mature wood. This suggests that wood properties of plantation-grown trees, to a large extent, depends on their juvenile wood contents, and can thus be manipulated effectively through rotation age. In general, the longer the rotation age, the lower the juvenile wood content, and the stronger the mechanical properties of the plantation-grown woods. However, the differences between juvenile wood and mature wood vary with wood properties and species. In general, juvenile wood and mature wood have less difference in chemical composition than in anatomical and physico-mechanical properties. Compared to the softwoods studied, the hardwoods appear to have less difference between juvenile wood and mature wood. Received 25 June 1999     

人工林杉木和杨树木材物理力学性质的株内变异研究

按照中国国家标准研究杉木和I-214杨树木材的抗弯弹性模量、抗弯强度、顺纹抗压强度和密度,同时按照日本国家标准研究2个树种的顺纹抗剪强度.结果表明:杉木的抗弯强度、顺纹抗压强度和密度由胸高直径处向上呈波浪形增加,抗弯弹性模量则稳定降低,但不同高度间杉木的物理力学性质没有显著差异;近树皮处木材的物理力学性质高于近髓心处木材,并有极显著差异.对于I-214杨树,只有抗弯弹性模量从髓心到树皮逐渐增加,其他的物理力学性质,最小值在从髓心到树皮的过渡区,最大值在近树皮处,从髓心到树皮,杨树的物理力学性质有极显著的差异.杉木和杨树的径面顺纹抗剪强度从髓心到树皮有极显著差异,并且近树皮的高于近髓心的木材,而弦面顺纹抗剪强度从髓心到树皮没有显著差异.木材密度与力学性质有很好的线性相关关系,木材密度是一个很好的力学强度的预测手段.     

木材的机械加工性能研究现状与进展

本文概述了木材机械加工性能研究的现状，介绍了木材加工性能测试和评价的标准。分析了进行木材机械加工性能研究的重要性和迫切性，并对木材机械加工性能的研究方向和发展趋势提出了建议。     

木材性质遗传变异规律的研究进展

木材性质的遗传改良是提高木材品质的重要措施之一，许多国家都相继开展了材性的遗传改良工作，以期能生产更多的优质木材。文中概述了国内外木材性质遗传变异规律的研究现状，并展望了进行材性遗传改良的前景。     

Relationship of selected cell characteristics and colour of silver birch wood after two different drying processes

Change in the colour of silver birch wood is a serious problem in the mechanical wood industry. Here, colour was correlated with microscopic characteristics of wood, such as cell types and dimensions, by drying processes. In conventional drying, with lower temperature than in vacuum drying used here, the most important factor causing darkened wood was wide latewood. In vacuum drying, thickness of the vessel walls affected wood darkening, as did broad rays and large amount of axial parenchyma. Axial and terminal parenchyma cells contained very small amounts of phenolics, but after drying at elevated temperature, a thin dark layer could be observed on the innerside of their walls. Phenolics were abundant in ray parenchyma; these compounds darkened at elevated temperatures, less in conventional drying than in vacuum drying. Phenolics were observed only inside cells, mainly in the parenchyma, but in vacuum-dried wood also in fibres and vessels. Anatomical characteristics are known to be affected by both environmental and genetic factors. Thus it might be possible to influence the colour reaction of birch wood during the drying process by choosing wood according to growing-site conditions, or by choosing the seed source for birch plantations according to given anatomical characteristics.