马尾松人工林材种出材率表的编制

应用马尾松人工林现场造材样木,根据胸径、树高与各材种出材率的关系,编制了二元材种出材率表,该表经检验证明适用。在此基础上,通过建立胸径、树高、地径之间的相关数学模型,导出了一元材种出材率表和地径出材率表。     

广西马尾松经济材出材率表编制研究

以马尾松人工林作为研究对象,用伐倒木样木数据,经干形分析和多指标精度比较,选定最佳的削度方程;通过树皮率方程和树高曲线方程进行计算机理论造材,依据各经济材种规格,编制出马尾松胸径树高二元经济材出材率表。经检验,以该方法编制的出材率表达到林业数表模型编制的精度要求。     

西江林业局尾巨桉人工林一元材种出材率表编制

在广东省西江林业局尾巨桉无性系人工林中选择并设置70个标准地,分别进行林分因子调查,同时选择163株样木以2.0 m或2.6 m段材长分径阶进行样木伐倒造材,以实际经济材造材出材率为基础拟合并选择较优的单株木一元材积比方程,然后根据材积比方程进行理论造材并编制尾巨桉单株木一元经济材出材率表;接着利用单株木一元经济材出材率表对所调查的标准地进行理论造材,以林分理论造材出材率为基础拟合并选择较优的林分一元材积比方程,最后根据材积比方程研制尾巨桉林分一元经济材出材率表。所编制的数表均符合国家精度检验标准,可为本地区桉树生产经营提供参考。     

闽东柳杉人工林林分出材率表的编制研究

利用柳杉人工林样木各部位直径测定数据,建立可变参数削度方程,配合威布尔分布函数、相对树高曲线模型及其他辅助方程,编制了柳杉人工林林分出材率表,为生产应用提供科学依据。     

吉林省蒙古栎削度方程与材种出材率表研究

利用在吉林省各县(市、区)所采集3 157株蒙古栎编表、验表样木数据,运用削度方程计算立木材积和材种出材率表,结果表明:运用削度方程可以灵活地反映树干上任意部位直径、既定直径处材长、材积、出材率、树干上任意分段材积和全树干材积;同时根据林分树高差异调整树高式参数,编制的材种出材率表精度高、适用性强,更符合林分中林木生长实际状况     

木荷单木材种出材率表编制的研究

利用木荷样木资料,在多个削度方程拟合对比的基础上,选择适合木荷干形变化规律的削度方程,据以编制单木一元材种出材率表和二元材种出材率表,可以林业生产应用提供科学依据。     

落叶松人工林材种出材率表的编制

落叶松人工林是黑龙江省重要的后备森林资源,占全省人工林总面积的36.4%,占总蓄积的47.5%,对其作出确切的质量评定,籍以提高经营管理水平,是当前极待解决的问题。为此我们在落叶松集中栽植的东部山区——小兴安岭、完达山和张广才岭,设置皆伐标准地24块,伐取样木5064株,分别编制了该区的一元材种出材率表、二元材种出材率表和树高级材种出材率表。在一元、二元和树高级材种出材率表中,一元材种出材率表使用最简便,但     

应用削度方程编制湿地松材积表和出材率表的研究

在树干形状研究的基础上,利用样木资料建立了一个适合湿地松人工林干形变化规律的可变参数削度方程,据以编制了一元材积表、二元材积表、一元材种出材率表和二元材种出材率表,这些数表经检验误差较小,精度较高,可在林业生产上推广应用。     

洋口林场杉木人工林材种出材率表的研究

根据洋口国有林场有代表性的杉木人工林样木资料,应用逐步回归技术和遗传算法建立可变参数削度方程,编制杉木人工林单木二元材种出材率表,为准确估算材种出材量提供了科学依据。     

三明市杉木、马尾松人工林材种出材率表编制的研究

三明市材种出材率表编制是根据部、省有关材种规格标准，进行现场造材，共收集１１６４株样木，其中杉木５５６株，马尾松６０８株。采用电子计算机对样木进行计算和分析，以确定各树种树高级、径阶、材积、树皮率、出材量和出材率。     

皖北杨树二元立木材积表的编制

以安徽省杨树人工林为研究对象,按照立木材积表编制要求,随机抽取329棵杨树伐倒木材积资料.以300棵样木资料为编表样本,选用3种数学模型为二元材积的候选模型,利用非线性麦夸特迭代求解法确定各模型参数、剩余标准差、相关指数.根据相关指数和剩余标准差,确定最优二元材积模型为:V=0.000 096 93d2.0123h0.6147".以29棵样木资料为验表样本,分别计算二元材积模型理论材积与实际材积的平均相对误差、平均绝对相对误差和系统误差,计算结果为:二元材积表分别是2.7%、8.6%、0.1%.各种材积误差均满足林业生产材积估算误差要求.     

一元材积表与一元出材率表的相关性分析——以福建省永安市尾叶桉为例

以福建省永安市尾叶桉一元材积表和一元材种出材率表为例,运用相关分析与曲线回归分析方法定量研究两数表中各径阶材积和总出材率之间的关系。研究结果表明:各径阶材积与出材率呈明显正相关关系,回归方程为y=e4.429-0.004/v,相关指数为0.997;永安市尾叶桉随着材积的增大,其出材率趋于84%。明确各径阶材积与出材率之间的关系,既可简化编表工作的人力、物力,为其他数表关系的研究提供参考,也可为完善林业数表体系提供依据。     

利用伐桩信息建立单株材积数学模型

调查被伐林木伐桩,推算林木材积,是林业生产实践中较为重大的问题。通常通过伐桩处的直径编制一元数表来计算被伐木的材积,这样存在着严重的偏差,将产生调查数据失真,将导致决策失误。充分利用伐桩的信息,建立三元变量数学模型,有利于提高森林资源调查数据的准确性和可靠性,可为相关科学决策提供比较真实的数学模型。     

对原木检验工作的几点思考

详细阐述利用原木横切面上木材的宏观结构特征和原木树皮及材表特征来识别原木树种的方法.以实例分别不同情况对原木尺寸的检量及其标准尺寸的确定方法进行全面阐述.对相关国家标准在实际运用中需要完善和灵活使用的有关方面提出了建议.     

塞罕坝主要天然次生林生长过程表的编制

利用林分生长过程表确定林分生长发育过程,在森林资源资产评估、安排森林经营措施、计算蓄积量、材种出材量和确定森林采伐量等生产经营过程中有着极其重要的作用。本研究以河北省塞罕坝主要天然次生林（白桦,山杨,柞树）为研究对象,在收集多年调查的临时样地数据的基础上,进行筛选、分析,从中选出584块符合条件要求的样地,借助Excel、SPSS11．0和ForStat统计分析软件,对中等立地条件下各树种的主要林分调查因子进行方程拟合,并对生长方程进行检验,分别编制了林分生长过程表,为该地区主要天然次生林的生长收获预估等森林经营活动提供了理论依据。     

Variation in wood density and carbon content of tropical plantation tree species from Ghana

Most research on carbon content of trees has focused on temperate species, with less information existing for tropical trees and very little for tropical plantations. This study investigated factors affecting the carbon content of nineteen tropical plantation tree species of ages seven to twelve and compared carbon content of Khaya species from two ecozones in Ghana. For all sample trees, volume of the main stem, wood density, wood carbon (C) concentration and C content were determined. Estimated stem volume for the 12-year-old trees varied widely among species, from 0.01 to 1.04 m³, with main stem C content ranging from 3 to 205 kg. Wood density among species varied from 0.27 to 0.76 g cm^?3, with faster growing species exhibiting lower density. Significant differences in wood density also occurred with position along the main stem. Carbon concentration also differed among tree species, ranging from 458 to 498 g kg^?1. Differences among species in main stem C content largely reflected differences among species in estimated main stem volume, with values modified somewhat by wood density and C concentration. The use of species-specific wood density values was more important for ensuring accurate conversion of estimated stem volumes to C content than was the use of species-specific C concentrations. Significant differences in wood density did exist between Khaya species from the wet and moist semi-deciduous ecozones, suggesting climatic and site factors may also need to be considered. Wood densities for these plantation grown trees were lower than literature values reported for the same species in natural forests, suggesting that the application of data derived from natural forests could result in overestimation of the biomass and C content of trees of the same species grown in plantations.     

样木解析法及其在材积表编制中的应用研究

提出了一种材积表编制样本资料收集的新方法———样木解析法。即在标准地中采用随机或机械抽样方法选取样木,进行树干解析,获得样木生长过程;通过建立树皮系数与树皮率回归模型,将样木解析后的各龄阶去皮直径和去皮材积转化为带皮直径和带皮材积,一株样木可获得龄阶数个编表样本。经四川农业大学实习林场楠木一元材积表、二元材积表编制实践,有减少编表样本收集工作量、消耗林木少的优点,且能达到精度要求,同时,也为珍稀树种材积表编制样本资料收集提供了新的方法。     

Evaluation of factors that have an influence on the fixation of chitosan in wood

When using chitosan as an antifungal agent in wood it is important to understand which factors contribute to a higher fixation ratio to optimize the utilization of chitosan, the active component. Small pine samples were impregnated with chitosan solutions varying in molecular weight, concentration, pH, polymerization agent, acid and degree of deacetylation. Different post-treatments such as time, temperature, moisture content and the effect of present air were applied to the samples to evaluate the effect on the relative retention. After impregnation, the samples, with a volume of 1.5 cm³, were leached in separate test-tubes according to EN-84. The samples were prepared in a paired design where both samples were impregnated, but only one was leached. Both leached and unleached samples were analysed for their chitosan content, and the relative ratio was used as a measure for the relative retention of chitosan during leaching. The results from these trials show that pH in the range of 5.1-5.9 is favourable. The molecular weight should be as high as possible yet able to penetrate the wood structure, and the use of acetic acid gives far better fixation than the use of hydrochloric acid.     

The effect of the G‐layer on the viscoelastic properties of tropical hardwoods

Context and aim

This study aimed to examine the effect of the tension wood G‐layer on the viscoelastic properties of wood.

Methods

Tension wood and opposite wood samples were obtained from six French Guianese tropical rainforest species (Sextonia rubra, Ocotea guyanensis, Inga alba, Tachigali melinoni, Iyranthera sagotiana and Virola michelii); the tension wood of the former three of these species had a G‐layer, whilst the tension wood from the latter three had no G‐layer. Tensile dynamic mechanical analysis (DMA) was performed on green never dried wood samples in the longitudinal direction with samples submerged in a water bath at a temperature (30°C) and frequency (1 Hz) representative of the conditions experienced by wood within a living tree. Then, DMA was repeated with samples conditioned to an air-dried state. Finally, samples were oven-dried to measure longitudinal shrinkage.

Results

Tension wood did not always have a higher longitudinal storage (elastic) modulus than opposite wood from the same tree regardless of the presence or absence of a G‐layer. For the species containing a G‐layer, tension wood had a higher damping coefficient and experienced a greater longitudinal shrinkage upon drying than opposite wood from the same species. No difference was found in damping coefficients between tension wood and opposite wood for the species that had no G‐layer.

Conclusion

It is proposed that the different molecular composition of the G-layer matrix has an influence on the viscoelasticity of wood, even if a biomechanical gain is not yet clear. This study shows that rheological properties and longitudinal shrinkage can be used to detect the presence of a G‐layer in tension wood.