不同潮位下角果木的种群发展趋势分析

为了阐明不同潮位下角果木Ceriops tagal种群的发展趋势,合理利用与保护现有的红树物种资源,通过野外样方调查与室内分析的统计学方法对不同潮位下的角果木种群进行调查,综合比较分析不同潮位生境下角果木的年龄结构,存活曲线与及静止生命表的差异,探究不同潮位生境下角果木的种群结构变化规律与发展趋势。构建高潮位生境下的种群动态的时间序列预测模型,预测了角果木种群其随着时间的变化种群的发展状况。结果表明,高潮位的生境下角果木种群呈现典型的"金字塔"增长型结构,种群处于不断增长趋势,存活曲线表现为凹形,即为DeeveeyⅢ。在低潮位的生境下,角果木的幼苗较多,但在生长发育过程中出现生长"瓶颈"现象,幼苗较难发育至成体树,种群呈现衰退的趋势。时间序列模型表明,高潮位生境下的角果木处于健康稳定的增长状态,种群的生长发育随着时间的变化而呈现出稳定的增长态势。     

顶果木木材干燥特性研究

为了掌握顶果木木材的干燥特性,制定合理的干燥基准,利用百度试验法研究了顶果木木材的干燥特性,结果表明:顶果木木材干燥速度为3级,较快;截面变形程度较轻,为1级;初期开裂较严重,为3级;扭曲等级为2级,有内裂。针对顶果木木材的干燥特性,参照百度试验缺陷等级以及干燥缺陷对应的干燥条件,拟定25~30mm厚为顶果木木材的干燥基准。在实际的窑干生产中只需对拟定的干燥基准进行适当的调整和优化便可以得到适合于顶果木木材的干燥基准,提高干燥基准的制定效率,为促进顶果木木材的开发和利用提供科学的理论依据。     

二氧化硅改良顶果木木材表面性质研究

以顶果木(Acrocarpus fraxinifolius)人工林木材为试验材料,对木材硅烷化改性前及改性后的顺纹抗压强度、硬度、尺寸稳定性和表面接触角等指标进行测定,结果表明:硅烷化改性后的顶果木的顺纹抗压强度得到明显增大,木材端面硬度在急剧减小后有缓慢回升,而径面的硬度是逐步增大。改性后的木材尺寸稳定性优于未改性的木材,改性后的木材接触角均大于90°,相比未改性的木材有了很大的改善,说明改性能明显提高顶果木木材的疏水性。     

银杏木材微纤丝角及其与生长轮密度相关模型的建立

通过对银杏木材微纤丝角的径向变化及其与生长轮密度相关性质的研究 ,结果表明 ,银杏木材平均微纤丝角为 1 8.5°,生长轮内早材微纤丝角较大 ,晚材较小 ;生长轮间沿径向呈减小趋势。木材微纤丝角与生长轮年龄、生长轮宽度、生长轮密度之间有较密切关系 ,建立了 5个相关模型 ,为银杏用材林的定向培育和木材加工利用提供依据     

顶果木人工林经济效益与成熟年龄研究

通过树干解析造材获得木材产量,采用动态和静态相结合的经济评价方法对桂中地区36年生顶果木人工林经济效益与成熟年龄进行研究。结果显示:顶果木36 a主伐时可获得木材845.7 m3·hm-2,木材销售收入889409.8元·hm-2。静态指标中,总利润达683642.2元·hm-2,投资利润率为9.23%,投资利税率为10.25%,投资回收期为35.02 a;动态经济指标的财务净现值为3972.0元·hm-2,财务内部收益率为13.22%。静态和动态经济指标均表明36 a的顶果木人工林造林项目盈利能力较强。造林项目敏感性分析表明,木材价格变化对经济效益的影响最明显,规格材盈亏临界价格为223.8元·m-3,财务净现值最大时作为经济成熟龄为18 a。     

海南岛树木资源(续11)

※密花核果木(D．congestifloraMerr．etT．Chun),密花核实;H(12),D(30)。尖堕,本岛西南部少见。皮灰褐;木材黄白,生长轮可见;材很重硬,加工稍难,耐腐。供建筑、地板、家具等。     

应用X射线衍射技术研究竹材超微结构Ⅰ.竹材纤丝角

厚壁细胞S2层纤丝角作为木材、棉花等纤维植物的重要参量已为许多文章所肯定.对于木材,纤丝角与材性、生长、解剖特性之间的关系,已有不少研究.     

江西大岗山木荷天然林群落物种多样性分析

分析了江西大岗山木荷天然林生长与生境的关系、群落结构特征及物种多样性,结果表明:木荷耐瘠薄、有很强的适应性,在土层较厚、阳光充足的条件下生长更好;在天然林群落中,木荷占主导地位且以高强度聚集方式存在;木荷天然林群落物种多样性较高,分布均匀。     

合果木苗期生长特性

合果木是云南省热带北缘及南亚热带珍贵的乡土速生用材树种。以西双版纳普文试验林场所培育的合果木苗木为研究对象,观测其苗高、地径月生长量,用Logistic、Richards、Chanter及Compertz等数学模型进行生长过程拟合,并以最适模型进行生长参数分析及生长期划分,以掌握合果木的生长特性。结果表明,苗高月生长在2月、5月、9月为生长高峰期,地径月生长在5月出现生长高峰,2月、9月则是地径生长速度的缓慢期;苗高和地径生长过程的折线图为"S"形,4种模型进行拟合效果都较好(P0.001,R~20.98);Logistic曲线方程能较好地反映合果木苗期地径生长以饱和值0.5倍处为对称的"S"形增长特性,依据Logistic曲线方程数学性质划分出的合果木苗期地径生长的4个时期(出苗期、前慢速生长期、速生期、后慢速生长期)较好地反映了合果木地径生长与当地气温、降水变化规律的一致性。     

顶果木种子解剖与催芽处理

顶果木(Acrocarpus fraxinifolius Wight)是含羞草科落叶大乔木,高达40余米,胸径1.5米,树干通直,材质好,有足够的力学强度,韧性良好,适于做各种建筑材料、家具及车辆用材。它生长迅速,10—15年成材,是亚热带、热带有前途的速生造林树种之一。我所于1976年在云南省的南部和西部发现野生顶果木,为了开发我国的速生树种资源,变野生为家生,提供更多、更好的速生树种,满足社会主义建设对木材日益     

Preparation and Characterization of the Phenolated Wood Using Sulfuric Acid as a Catalyst Ⅱ. FT-IR and GPC Characterization

By means of gel permeation chromatography analysis, the molecular weight of liquefied wood under different reaction conditions was investigated to trace the change in the structural characteristics of the liquefied wood. The insoluble residues were analyzed by Fourier transform infrared to investigate the liquefaction order of three main wood components. The results indicate that both reaction temperature and reaction time could affect the molecular characteristics of the liquefied wood obtained. The molecular weight of liquefied Chinese Fir wood is higher than that of liquefied Poplar wood under most of reaction conditions. During wood liquefaction, lignin is liquefied firstly. Hemicellulose is liquefied in the middle stage and cellulose is the most difficult to be liquefied.     

角果木的育苗与造林技术

角果木是红树林的主要组成树种之一。文章介绍了角果木的生物学特性,并总结了角果木营养袋育苗技术、幼苗造林与管护措施,为红树林苗木生产和生态恢复提供技术指导,对提高广东省红树林生物多样性具有重要意义。     

Severe hail damage to mangroves at Port Curtis, Australia

A hailstorm in October 1994 was found to have moderately or severely impacted on 5.3% of the mangrove forests in Port Curtis. All mangrove species showed evidence of hail damage, including the three most common species (Rhizophora stylosa, Ceriops tagal and Avicennia marina). Physical effects of hail damage included stripping of leaves from plants, holes punched through leaves, bruising to bark, divots removed from bark, branch and plant death. Speciesspecific differences in vulnerability to the effects of hail were observed with C.tagal experiencing relatively higher mortality rates than the other two common mangrove species. A delayed pattern of mortality was observed in two species _ C.tagal and A.marina. Alterations to mangrove community structure included: (1) reductions in stem density, stem diameter and basal area, (2) reductions in canopy cover (based on a photographic index of foliage projective cover) and (3) changes in relative abundance of species in mangrove zones. Recovery was observed in some stands but others had not recovered to prehail levels of canopy cover two years after the hailstorm. Recovery had occurred by regeneration of fresh leaves but no recruitment of young plants had been observed during the study. The forests in the impact area were dominated by either Ceriops tagal or Rhizophora stylosa with Avicennia marinaas a subdominant in places. C.tagal dominated forests within the impact area were relatively more severely affected (41.8% in the severe category) than R.stylosa dominated communities (only 17.4% in the severe category). This indicated that C.tagal dominated forests were more vulnerable to the effects of hail damage than R.stylosa dominated forests. In addition, hailimpacted C.tagal dominated forests represented a relatively high percentage of the area of C.tagal dominated forests in Port Curtis (44.3%). This percentage was much higher than hailimpacted R.stylosa dominated forests in Port Curtis (2.7%). These two factors – relatively severe impact on C.tagal communities and a relatively higher percentage affected within the Port Curtis area – illustrate that hailstorms, as a form of natural disturbance, are an important influence on the forest ecology of mangrove ecosystems in this region.     

松材线虫病病程特征变化的研究

为提高从松树病死木上取样分离松材线虫的检出率,及时、准确诊断疫木和疫点,根据病害的外部症状,把松材线虫病发病过程分为四个阶段,对各阶段的松材线虫分布、松褐天牛发生情况、含水率的变化、木材蓝变情况等特征进行研究。结果表明：病死木上松材线虫的分布由多到少为：发病前期上部>中部>下部,后期上部<中部<下部,松材线虫的数量与松褐天牛老熟幼虫的数量呈正相关,最佳的取样阶段为第Ⅱ和第Ⅲ阶段靠上部稍段取样,第Ⅳ阶段偏下部取样。     

木材内部水分扩散特性研究现状及发展趋势

扩散是水分在木材内部移动的一种重要途径。文中围绕木材内部水分的扩散机理、测试方法及其影响因素3个方面阐述水分扩散的驱动力类型及其在木材内部的基本移动路径,总结稳态和非稳态水分扩散系数的测试及计算方法;综述树种、早/晚材、心/边材、幼龄/成熟材等因素对水分扩散特性的影响机制;归纳木材含水率、温度等因素对木材内部水分扩散的作用规律;结合国内外关于水分扩散的研究现状,指出一些亟待解决的问题,以期为木材干燥、木结构建筑、木质包装材料的研究与应用提供参考。     

The ultrastructure of cellulose from wood

Summary During the delignification of wood several processes overlap one another. One of these is the penetration of the wood samples by the delignifying solution. Penetration tests under different conditions show that there is almost no difference in the penetration depth of wood samples penetrated by diffusion only and of wood samples treated with pressure. In both cases the pits are closed during the flow of fluids. Vacuum treated samples show better penetration and most of the pits in these samples remain open. The distribution of fluids within the cell walls takes place in the intercellular spaces, in small openings in the compound middle lamella and in the secondary wall 1 as well as in very fine pores in the secondary wall 2. The penetration of a wood sample is greatly facilitated if the sample is mechanically injured. A slowly proceeding delignification with ethylene sulphite shows that the delignification obviously starts in the S 1 layer and proceeds from there towards the compound middle lamella and the S 2 layer. In the first stages of lignin removal the compound middle lamella is also attacked, the attack beginning at the border of the pit chambers.     

木材苯酚液化产物制备碳纤维的初步探讨

为拓宽木材液化产物的应用领域,提高木材产品的附加值,实现木材的高效利用,在研究木材苯酚液化产物特性的基础上,提出了木材苯酚液化产物碳纤维材料的制备构思和工艺路线。利用木材苯酚液化产物为前驱体,通过加入反应剂如六次甲基四胺等调制纺丝液,熔融纺丝后将纤丝在甲醛和盐酸混合溶液中加热固化形成网状交联结构,然后在惰性气体保护下高温炭化制备成碳纤维,同时对制备过程中可能存在的影响因素进行了分析。     

基于声波的木材孔洞位置检测的探讨

针对不同位置孔洞缺陷的木材,进行室内敲击试验。试验收集木材受敲击时发出的声音信号,并对信号进行数据分析,研究具有不同缺陷的木材在不同敲击条件下共振频率的变化,并探讨此共振频率与木材缺陷的对应关系。结果表明,木材在不同缺陷条件下（无孔洞／有中间孔洞／有端部孔洞）的共振频率有明显不同,且这种对应关系仅与缺陷情况有关,与敲击力度和敲击方位无关。通过检测木材的声音共振频率来判定木材孔洞位置的方法是可行的。     

基于计算机的木材特征提取和分类识别技术研究综述

木材由于内部结构和组成成分的差异,使不同种类木材表现出完全不同的理化性质,并决定其不同的用途和商业价格,因此针对木材的分类识别研究具有重要的应用价值。木材分类识别通常经过木材特征提取和基于特征的分类识别这2个步骤。目前木材特征提取主要利用计算机视觉、光谱分析等技术。木材分类识别是基于木材特征的数字化,这一部分可利用计算机算法实现自动识别,较以往人工识别可大幅提高准确度。文中通过分析近20年来木材特征提取和分类识别的相关文献,介绍各种基于计算机的木材特征提取与分类识别技术的特点及适用范围,并结合计算机技术的发展方向探讨木材特征提取与分类识别技术的发展趋势,以期为构建更准确的木材分类识别技术提供参考。     

声发射技术在木材加工领域的应用

作为一种主动无损检测方式, 声发射技术通过分析被测物体内部因能量变化所引发的弹性波的特征, 判断物体内部损伤程度并确定损伤位置。声发射技术为木材加工过程应力监测提供了一种主动无损检测模式, 但受木材自身各向异性等特点的限制, 目前声发射技术在木材工业中的应用尚处于探索阶段。为此, 文中重点介绍了目前声发射技术在木材切削加工、木材及木质结构、木材力学性能、木材干燥过程等木材加工过程的应用现状, 并在此基础上根据木材声发射信号特点, 提出一种基于LabView及高速采集设备的木材干燥过程声发射监测系统设计方案。