原木形状分段描述方法的数学描述理论研究

为制材、木材检尺等特殊行业需要的原木数控检测提供数学描述理论,提出的这些理论将为数控检测的数学模型建立提供具体的数学方法,为原木形状的视频再现提供编程的数学工具．本文提出的理论还将为数控下锯法提供理论依据,与制材工艺结合起来,将使传统原木检测数字化,为科学管理原木和数字化统计与检尺控制提供了理论,本文是木材工业中用数学描述检测过程的开始．通过本文的研究,可以推进木材工业检测过程数学描述研究的开展．     

旱冬瓜育苗和造林技术

本文对旱冬瓜进行了播种、育苗、造林等方面的概述,其中播种育苗要掌握好采种时间、种子处理及播种时间,造林在夏季及时进行,采用宽窄行种植,提高木材质量和出材率。     

利用板材端面纹理判断和识别板材几何参数的数学描述理论

为家具、乐器、考古鉴定等特殊行业需要对木材的材种和板材的下锯位置及板材进行识别提供数学方法,利用一般喷漆成品木材端面纹理往往可以显现的特点识别木材年轮宽度、锯材在原木中的下锯位置、原木椭圆度等参数．提出这些数学理论将为木材几何参数识别的数学模型建立提供工具,还将为珍贵树种木材识别提供理论依据,为古代家具品质鉴别提供科学的方法,这些理论将使传统人工识别工艺数学化,实现科学考古和鉴定数字化。     

纸张生态足迹

自1960年代以来,由于废纸浆在全球造纸浆中比例不断提高,原有的纸张生态足迹计算方法--以原木浆纸的木材消耗量为计算基础--需要改进.通过分析纸浆结构的变化、纸浆与纸的关系、纸浆耗木量、废纸成浆率等,定量地表征了废纸回收对纸张木材消耗的影响,得出1t纸消耗的木材应为3.879 m3而略小于原来的4 m3的结论.在此基础上,重新计算纸张的生态足迹,得出1t纸的生态足迹为2.569 hm2森林.     

林业剩余物资源量评估方法

根据近十年来相关文献报道,分析了前人所建方法的合理性,结合中国林业生产实际,完善了林业剩余物资源潜力的计算方法。主要贡献包括:林业剩余物第二级分类的10个主要类型,即林木苗圃剩余物、林木修枝剩余物、木材采伐剩余物、木材造材剩余物、木材加工剩余物、竹材加工剩余物、薪材、废旧竹材、废旧木材、香蕉和菠萝残体;将经济林采伐和进口原木产生的剩余物计入相关木材剩余物计算范围;首次建立了包括木本水果在内的林木修枝剩余物的计算方法,以及多年生草本水果剩余物即香蕉和菠萝残体产量的计算方法;确定计算公式中参数所需要数据的来源;建议今后重点研究相关系数取值、林业剩余物资源量及其空间分布和相关行业标准等。     

斯氏线虫在进境原木害虫检疫处理上的应用前景

本文综述了我国进境原木上截获的主要害虫类群;总结了目前进境原木害虫的检疫处理技术;重点介绍了斯氏线虫Steinernema sp.对钻蛀性害虫的防治研究,探讨了斯氏线虫在进境原木害虫检疫处理上的应用前景,提出了应用斯氏线虫防治进境原木害虫所存在的问题及今后的研究方向.     

进口原木中截获的刺角沟额天牛的研究

<正> 刺角沟额天牛Hoplocerambyx spinicornis(Newman)是多次在海口口岸从马来西亚进口的梢原木中截获的1种我国尚未发现有分布的危险性林木害虫。在印度它被列为“最危险的森林害虫”。与我毗邻各国大多有此虫分布,日本在进口原木中也将该虫传入本土。为此,各口岸动植物检疫所对从东洋区进口的木材应重视该虫的检疫。我们从1985～1990年对该虫的成、幼虫形态特征、寄主植物、为害情况等进行了研究,并用检疫中截获的初龄幼虫     

从马来西亚进口原木中输入的天牛

最近,笔者在鉴定由中华人民共和国广州动植物检疫所雷淑媚同志送来的从马来西亚进口原木中输入的天牛,共有八种。其中三种〔黄八星白条天牛Batocera rubus Linnaeus 1785,地衣天牛Palimna annulata(0livier)1792及刺缝裂眼天牛Dialeges Pauper Pascoe 1856〕在国内有分布。这些新输入的天牛种类,有可能在与马来西亚气候相近的我国南部地区存活而成为新的木材害虫。为此,极需我国有关方面在各口岸立即加强对进口林木的检疫工作,并建议就地采用辐射杀虫或其它措施杀灭进口原木中的天牛等害虫,以免蔓延为害。     

浅谈如何运用林学理论提高木材检验工作质量

加强木材检验工作的质量可以提高对木材的利用效率,进而可以缓解木材紧缺的供需矛盾。在木材检测质量体系的建设和管理上加大创新的力度是今后工作的重点,通过加强管理和强化服务严把木材检验质量关口,为木材的生产和销售工作提供可靠的质量保证。鉴于提高木材检验工作质量的重要性,本文主要从林学理论的视角对如何提高木材检验的工作质量进行了系统阐述。     

广西柳杉木材构造、材性研究

南丹大塘山林场所产的柳杉生长良好,年轮平均宽度达0.8cm左右,比生长在南丹的杉木还要宽,在木材构造方面,柳杉管胞(纤维)的长度、直径、胞壁厚度等都稍低于杉木,其中差距较大为早材管胞长度。从木材性质来看,除年轮宽度、弦径干缩比、弦面抗劈力、冲击韧性稍大于杉木外,余均稍低于杉木;柳杉木材质量系数为中质量,强度性质为低的一级,其他强重比如顺压、抗弯等虽稍低于杉木,但在一般用途可以适应的。无论在化工原料、原木利用,交通运输、一般用器都具有一定的经济价值。     

Review of environmental effects and treatment of runoff from storage and handling of wood

This review paper summarises the environmental effects of runoff from wood handling sites including log yards. The characteristics of site runoff and the corresponding effects on the receiving watercourses are presented for worldwide case studies, highlighting the urgent need to address the water pollution problem associated with the wood industry. The methods used to reduce the negative environmental impact of the runoff, such as constructed wetlands, soil infiltration and chemical oxidation, are evaluated. The principal environmental problem of runoff is usually the high concentration of organic substances originating from the wood and bark, some of which are toxic to aquatic life. Phosphorus is also a problem according to some studies. The toxicity of the runoff varies greatly, and depends on the species of tree stored, the amount of water the wood has been in contact with and the degree of runoff treatment.     

Biomechanical design and long-term stability of trees: Morphological and wood traits involved in the balance between weight increase and the gravitropic reaction

Studies on tree biomechanical design usually focus on stem stiffness, resistance to breakage or uprooting, and elastic stability. Here we consider another biomechanical constraint related to the interaction between growth and gravity. Because stems are slender structures and are never perfectly symmetric, the increase in tree mass always causes bending movements. Given the current mechanical design of trees, integration of these movements over time would ultimately lead to a weeping habit unless some gravitropic correction occurs. This correction is achieved by asymmetric internal forces induced during the maturation of new wood.The long-term stability of a growing stem therefore depends on how the gravitropic correction that is generated by diameter growth balances the disturbance due to increasing self weight. General mechanical formulations based on beam theory are proposed to model these phenomena. The rates of disturbance and correction associated with a growth increment are deduced and expressed as a function of elementary traits of stem morphology, cross-section anatomy and wood properties. Evaluation of these traits using previously published data shows that the balance between the correction and the disturbance strongly depends on the efficiency of the gravitropic correction, which depends on the asymmetry of wood maturation strain, eccentric growth, and gradients in wood stiffness. By combining disturbance and correction rates, the gravitropic performance indicates the dynamics of stem bending during growth. It depends on stem biomechanical traits and dimensions. By analyzing dimensional effects, we show that the necessity for gravitropic correction might constrain stem allometric growth in the long-term. This constraint is compared to the requirement for elastic stability, showing that gravitropic performance limits the increase in height of tilted stem and branches. The performance of this function may thus limit the slenderness and lean of stems, and therefore the ability of the tree to capture light in a heterogeneous environment.     

Bofu-Tsu-Shosan,an Oriental Herbal Medicine,Exerts a Combinatorial Favorable Metabolic Modulation Including Antihypertensive Effect on a Mouse Model of Human Metabolic Disorders with Visceral Obesity

Accumulating evidence indicates that metabolic dysfunction with visceral obesity is a major medical problem associated with the development of hypertension, type 2 diabetes (T2DM) and dyslipidemia, and ultimately severe cardiovascular and renal disease. Therefore, an effective anti-obesity treatment with a concomitant improvement in metabolic profile is important for the treatment of metabolic dysfunction with visceral obesity. Bofu-tsu-shosan (BOF) is one of oriental herbal medicine and is clinically available to treat obesity in Japan. Although BOF is a candidate as a novel therapeutic strategy to improve metabolic dysfunction with obesity, the mechanism of its beneficial effect is not fully elucidated. Here, we investigated mechanism of therapeutic effects of BOF on KKAy mice, a model of human metabolic disorders with obesity. Chronic treatment of KKAy mice with BOF persistently decreased food intake, body weight gain, low-density lipoprotein cholesterol and systolic blood pressure. In addition, both tissue weight and cell size of white adipose tissue (WAT) were decreased, with concomitant increases in the expression of adiponectin and peroxisome proliferator-activated receptors genes in WAT as well as the circulating adiponectin level by BOF treatment. Furthermore, gene expression of uncoupling protein-1, a thermogenesis factor, in brown adipose tissue and rectal temperature were both elevated by BOF. Intriguingly, plasma acylated-ghrelin, an active form of orexigenic hormone, and short-term food intake were significantly decreased by single bolus administration of BOF. These results indicate that BOF exerts a combinatorial favorable metabolic modulation including antihypertensive effect, at least partially, via its beneficial effect on adipose tissue function and its appetite-inhibitory property through suppression on the ghrelin system.     

Quantification of Trends in Wood Production Within Trees of Silver Birch (Betula pendula Roth.)

Trends in rate and duration of wood production are analysedalong and between branches, and along main stems of silver birch(Betula pendula Roth.) trees (at early canopy closure and closedcanopy stages of growth). These data are discussed in relationto the control of knot size, log diameter and taper. To providea field guide to cambial reactivation, progress of vessel productionhas been related to stages of leaf expansion.Copyright 1994,1999 Academic Press Betula pendula (Roth.), silver birch, cambial activity, wood production, wood quality, vessel production     

Forest farming of shiitake mushrooms: An integrated evaluation of management practices

Two outdoor shiitake (Lentinula edodes) cultivation experiments, established in Missouri USA in 1999 and 2000, produced mushrooms in 2000–2005. We examined shiitake production in response to substrate species, inoculum form, inoculum strain, and inoculation timing, using total mushroom weight per log as the primary response variable with log characteristics as covariates. The significantly greater mushroom weight produced by sugar maple logs compared with white or northern red oak was attributable to the higher proportion of undiscolored wood volume in the maple logs, rather than to bark thickness or log diameter. The “wide temperature range” shiitake strain produced significantly greater yield compared with the “warm” or “cold” weather strains. Both the wide-range and warm-weather strains were stimulated to fruit by significant rain events, while the cold-weather strain was responsive to temperature. Inoculation with sawdust spawn gave significantly greater yield than colonized wooden dowels or pre-packaged “thimble” plug inoculum. The second and third full years following inoculation were the most productive.     

Species richness of tropical wood-inhabiting macrofungi provides support for species-energy theory

A study was undertaken at the El Verde Field Station in Puerto Rico to determine the effect of energy available from newly dead trees on the species richness of macrofungal communities that inhabit them. It is hypothesized that there is a positive relationship between available energy and species richness. Energy was measured using the volume of the dead trees and the wood density of living trees of the same species. One hundred ninety-four logs of known tree species were surveyed 1 y for fruiting bodies of macrofungi at monthly intervals. For individual logs, log volume had a significant positive effect on macrofungal species richness. Younger logs had significantly higher species richness than older logs, and those with less apparent decay had more species than those with more decay. When logs were grouped by tree species, total wood volume and density of live wood had a significant positive effect and average log diameter had a negative effect on total species richness and abundance of the wood-inhabiting macrofungi. Macrofungal richness and abundance constantly increased with initial wood density; there was no evidence for a unimodal relationship. These results support the proposed relationship between species richness and energy.     

The mechanical role of bark

The ability of stem bark to resist bending forces was examined by testing in bending segments of Acer saccharum, Fraxinus americana, and Quercus robur branches with and without their bark. For each species, the bark contributed significantly to the ability of stem segments differing in age to resist bending forces, but its contribution was age-dependent and differed among the three species. The importance of the mechanical role of the bark decreased basipetally with increasing age of F. americana and Q. robur stem segments and was superceded by that of the wood for segments ≥ 6 yr old. A. saccharum bark was as mechanically important as the wood for stem segments 7 yr old but was not a significant stiffening agent for younger or older portions of stems. On average, the stiffness of the bark from all three species was 50% that of the wood. However, the geometric contribution to the flexural rigidity of stems made by the bark (i.e., the bark's second moment of area) was sufficiently large to offset its lower stiffness (Young's modulus) relative to that of the wood. A simple model is presented that shows that the bark must be as mechanically important as the wood when its radial thickness equals 32% that of the wood and its stiffness is 50% that of the wood. Based on this model, which is shown to comply with the data from three species purported to have stiff woods, it is evident that the role of the bark cannot be neglected when considering the mechanical behavior of juvenile woody stems subjected to externally applied bending forces.     

Woody Debris Volume Depletion Through Decay: Implications for Biomass and Carbon Accounting

Woody debris decay rates have recently received much attention because of the need to quantify temporal changes in forest carbon stocks. Published decay rates, available for many species, are commonly used to characterize deadwood biomass and carbon depletion. However, decay rates are often derived from reductions in wood density through time, which when used to model biomass and carbon depletion are known to underestimate rate loss because they fail to account for volume reduction (changes in log shape) as decay progresses. We present a method for estimating changes in log volume through time and illustrate the method using a chronosequence approach. The method is based on the observation, confirmed herein, that decaying logs have a collapse ratio (cross-sectional height/width) that can serve as a surrogate for the volume remaining. Combining the resulting volume loss with concurrent changes in wood density from the same logs then allowed us to quantify biomass and carbon depletion for three study species. Results show that volume, density, and biomass follow distinct depletion curves during decomposition. Volume showed an initial lag period (log dimensions remained unchanged), even while wood density was being reduced. However, once volume depletion began, biomass loss (the product of density and volume depletion) occurred much more rapidly than density alone. At the temporal limit of our data, the proportion of the biomass remaining was roughly half that of the density remaining. Accounting for log volume depletion, as demonstrated in this study, provides a comprehensive characterization of deadwood decomposition, thereby improving biomass-loss and carbon-accounting models.     

Effects of bending stress on taper and growth of stems of youngEucalyptus regnans trees

A glasshouse experiment investigated the effect of bending stress on stem radial and height growth and stem taper ofEucalyptus regnans seedlings. Eighteen-week-old, potted seedlings were bent continuously for 8 weeks with a static bending stress. The bending treatment was then removed and the seedlings grown for another 12 weeks. Other seedlings were stayed vertically throughout the experiment whilst control seedlings were neither bent nor stayed. Seedlings were rotated every 2 days to prevent reaction wood developing asymmetrically in the stems of bent trees. Bent trees had higher radial growth rates, developed more tapered stems and had higher safety factors (the ratio of stem radius to the minimum radius required to prevent the tree toppling over) than unbent seedlings. They produced a band of tension wood in their stems and ceased height growth whilst bent. When bending ceased, they resumed normal radial and height growth. Unbent trees developed more cylindrical stems. There were no differences in growth behaviour between stayed and control trees. Bent and unbent trees all developed a butt swell, the taper of which was not affected by treatment. It was concluded that bending stress has substantial effects on both the size and taper of tree stems. However, the development of butt swell is independent of the bending stress applied. The results were considered in relation to biomechanical theories of tree stem development.