马占相思抗旱性生理指标的选择研究

为了研究影响马占相思抗旱能力的主导因素,对马占相思在渗透胁迫过程中的相对电导率、相对含水量等9个生理指标进行了测定,并利用SAS软件对这些指标进行了主成分分析.分析表明:维持膜的稳定性的水分生理指标--相对电导率、相对含水量、自然饱和亏是马占相思抗旱性测定的主要指标,其次是代表渗透调节因子的可溶性糖和游离脯氨酸这两个指标.     

3种相思幼苗抗旱性研究

以聚乙二醇（PEG-6000）的渗透溶液模拟水分胁迫条件，比较了不同水分胁迫强度下3种相思幼苗的抗旱性，并确定了鉴定幼苗抗旱性的生理指标。结果表明：相对电导率、相对含水量、相对水分亏缺、可溶性糖含量、游离脯氨酸等指标可作为鉴定相思幼苗早期抗旱性的生理指标；3个树种的抗旱能力排序为：厚荚相思〉大叶相思〉马占相思。     

3种相思苗期耐旱性评估与选择研究

以聚乙二醇（PEG 6000）的渗透溶液模拟水分胁迫条件,通过测定相对电导率、相对含水量等指标,对南亚热带的马占相思、大叶相思、厚荚相思的幼苗进行了耐旱性评估和选择。结果表明：3种相思幼苗的耐旱能力在树种、种源和家系3个层次上均存在极显著的差异。针对3个相思树种分别从种源/家系水平上筛选出一批耐旱材料：马占相思15678种源中的BVG00667和BVG00669家系,种源16990中的MM000978家系;大叶相思18854种源中的2913、2900、2928、2921、2925家系以及种源18924中的BVG2712、BVG2713家系;厚荚相思13681种源63、24家系,16986种源16家系,以及15646种源73家系。     

三种相思品种材性与制浆性能比较

对6年生马占相思、大叶相思和厚荚相思进行纤维形态和化学组成的分析测定,同时并在优化工艺条件下进行了蒸煮实验,进而对其综合制浆性能和纸浆强度进行了比较,结果显示,大叶相思从纤维形态、化学组成和制浆得率以及纸浆强度各项指标上而言,都是较好的,适于营造造纸用的速生丰产林.     

不同处理对大叶相思幼苗抗逆性及造林效果的研究

为了提高大叶相思幼苗在干热河谷地区造林的成活率,2008年在元江通过对其幼苗分别进行不同剂量的Pt菌剂、干旱胁迫和Pt菌剂+干旱胁迫处理,测定出圃幼苗的苗高、地径、高径比、生物量等形态指标和叶绿素、可溶性糖含量及SOD酶活性等生理指标,并比较其抗逆性,同时对不同培育措施出圃幼苗造林6个月时的成活率和生长状况进行测定与比较。结果表明:随着Pt菌剂的使用量增加,大叶相思出圃苗木的高径比和地上部分和地下部分生物量的比值逐渐降低,SOD酶活性和可溶性糖含量逐渐增加,因而出圃幼苗的抗逆性增强;干旱胁迫和Pt菌剂的作用效果可以叠加。Pt菌剂10 g+干旱胁迫大叶相思的处理效果最佳,成活率最高。     

不同密度大叶相思的土壤物理性质试验

对不同密度的4年生大叶相思林的土壤物理性质(容重、总孔隙度、毛管持水量、毛管孔隙度、非毛管孔隙度及自然含水量)进行了试验研究,结果表明:除中低密度大叶相思林非毛管孔隙度显著大于高密度的,以及高、中密度大叶相思自然含水量显著大于低密度的外,其他各物理性质之间差异不显著。由此可见,三种密度大叶相思林的物理性质相近。期望研究为合理管理大叶相思人工林提供理论依据。     

Selection of Cold Tolerance of Acacia auriculaeformis

采用电导法对大叶相思5个种源,15个家系进行了耐寒性测定和评估.试验结果表明:大叶相思的低温半致死温度为0.605 8℃.大叶相思种源间和家系间耐寒能力差异显著,其中种源的耐寒性从高到低排序为19244＞ 18924＞ 17966＞ 18854＞ 19250;相对耐寒的家系为JSL1303和BVG2726,JSL1358家系的耐寒能力最差.     

大叶相思抗寒性选择研究

采用电导法对大叶相思5个种源,15个家系进行了耐寒性测定和评估。试验结果表明:大叶相思的低温半致死温度为0.605 8℃。大叶相思种源间和家系间耐寒能力差异显著,其中种源的耐寒性从高到低排序为19244>18924>17966>18854>19250;相对耐寒的家系为JSL1303和BVG2726,JSL1358家系的耐寒能力最差。     

5种典型热带引种园林植物幼苗抗寒性研究

选取广州地区5种常见引种园林植物的苗木,包括凤凰木、塞楝、大叶榄仁Terminalia catappa、马占相思、铁刀木作为材料,采用人工气候箱进行1℃、9℃、17℃、25℃连续18 d的不同程度冷冻处理,研究了低温胁迫下树苗生长发育有关的生理生化指标的变化与抗冻害的关系。结果表明:随着处理温度的降低,各树种叶片的相对电导率呈上升趋势,塞楝和马占相思上升比凤凰木、铁刀木、大叶榄仁慢;低温胁迫的各种苗木叶片内的脯氨酸大于对照组,其中马占相思的脯氨酸增加率最大;除塞楝外各种苗木POD活性先是缓慢升高,然后随低温胁迫程度加快升高;相对电导率结合Logistic方程推算塞楝和马占相思的半致死温度(LT50),分别为8.99℃、7.62℃。抗寒性综合评价表明,5种苗木的抗寒能力排序为马占相思>塞楝>铁刀木>凤凰木、大叶榄仁。     

平潭沙地木麻黄大叶相思混交造林效果研究

在木麻黄采伐迹地上开展了木麻黄大叶相思行状混交造林试验,以木麻黄纯林作为对照。对造林8年的试验林进行了生长量、防风效能以及土壤肥力测定,结果表明:木麻黄与大叶相思混交林其生长量大于木麻黄纯林,混交林的蓄积量高于纯林,木麻黄大叶相思1∶3混交林中木麻黄生长量和林分总蓄积量最大;木麻黄大叶相思混交林防风效能大于木麻黄纯林,木麻黄大叶相思按1∶3比例混交的林分防风效果最好;木麻黄大叶相思混交林土壤肥力高于木麻黄纯林,木麻黄大叶相思1∶3混交林土壤肥力最高。沿海沙地营造木麻黄大叶相思混交林时建议单行木麻黄与多行大叶相思混交。     

森林可燃物湿度研究综述

森林可燃物湿度对林火蔓延和有效辐射率均有重大影响。它又是预测林火发生、林火行为、火险等级的主要根据。本文在回顾森林可燃物湿度研究的同时, 综述了可燃物湿度研究的两个重要的概念—平衡含水量和时滞, 简述了相对湿度理论, 概括了主要研究方法的优缺点。文中还列出了现代可燃物研究的主要成果, 指出了可燃物湿度研究的发展方向。     

浅谈在家具生产加工中如何有效地控制含水率

我国家具出口的速度增长很快,但是在家具出口后因质量而产生的索赔问题也不少,其中,含水率问题是比较突出的。由于含水率没有控制好,到达国外后家具的零部件就出现了开裂、弯曲变形等现象,因此,在家具生产加工中科学有效地控制含水率就显得十分重要。     

Moisture content penetration in wood elements under varying boundary conditions

Knowledge of effects of moisture exposure on timber structures is important for serviceability and load bearing capacity of timber elements and systems. Varying climate affects the moisture content profiles in timber as the relative humidity changes in the ambient air. This paper presents methods for calculation of diffusion based moisture transport and corresponding results on how timber responds to varying moisture with regard to moisture penetration and distribution. The calculations are based on measured outdoor relative humidity and temperature at different climatic locations in Sweden. No remarkably large deviations between the different climatic locations were found in general, which is positive in a design code perspective.     

不同结构防护林土壤水分的特征分析

基于对和田绿洲不同结构防护林土壤理化性质的测定结果,分析了不同结构防护林土壤水分的分布特征,并讨论了土壤水分与土壤理化性质之间的关系。结果表明,防护林土壤水分具有规律性分布特征,即从防护林西南方向到东北方向,土壤的相对含水率呈增大趋势,且不同结构防护林土壤相对含水率大小各异。防护林土壤水分与土壤热容量呈显著的线性(R2=0.990 3)正相关,与土壤全盐含量呈一定的梯度分布。不同结构防护林土壤水溶性盐分的空间变化明显,防护林土壤有一定的积盐特征,土壤全盐含量已从2008年的0.444 g.kg-1变为2009年的10.332 g.kg-1。     

The frequency dependence of hygro-expansive scaling of oak

ABSTRACT

Fluctuations in the ambient relative humidity are often cyclic of nature, composed of a wide variety of frequencies. Variations may be as fast as one minute or as slow as a complete season. A wooden object exposed to these fluctuations exchanges moisture with the air, resulting in a change in the local moisture content of the wood. Since moisture penetration is affected by the timescale of the changes in ambient conditions, so are processes caused by moisture content variations. Moisture content variations cause dimensional changes of a wooden object, which, if mechanically restrained, lead to a buildup of stresses and ultimately to damage. It is therefore important to predict the frequency behavior of moisture content and expansion in wood. In the presented study, experiments are conducted in which the moisture content and expansion of oak cubes with different sizes is measured during sinusoidal relative humidity fluctuations with different frequencies. The amplitude in moisture content and expansion is shown to be simply scalable based on sample size only. Derived diffusion coefficients are in agreement with literature values, although the experimental frequency behavior is shown to deviate qualitatively from diffusive frequency behavior.     

Water content measurement in black spruce and aspen sapwood with benchtop and portable magnetic resonance devices

Abstract

In this study, water content in black spruce (Picea mariana Mill.) and aspen (Populus tremuloides Michx.) sapwood samples was investigated with time-domain magnetic resonance (MR). Time-domain MR measurements easily distinguish water in different environments in wood according to the spin-spin relaxation time and provide quantitative information on water content. The MR techniques employed can distinguish and quantify the individual signal components. Both black spruce and aspen have two signal components at moisture contents above the fiber saturation point. These two signal components correspond to motionally restricted water, often referred to as bound water, and unrestricted, or free water. Bound water content is constant above 40% moisture content. No signal from free water was detected at or below 20% moisture content in either species. We also demonstrate the use of a recently developed portable unilateral magnet that can be employed as a powerful tool in the study and measurement of water content in wood.     

Fundamentals of flakeboard manufacture: wood-moisture relationships

Summary A procedure is presented to estimate the relative vapor pressure, equilibrium moisture content, average flake temperature, and average flake moisture content in a flakeboard mat during hot-pressing. This method is based on measurements of temperature and total gas pressure in the mat during hot-pressing. A heat and mass transfer model was adapted from the literature to predict the temperature and moisture content inside an individual flake. Significant moisture gradients are predicted to develop within flakes. Convective heat transfer appears to control the change of moisture content within a flake. Thermodynamic equilibrium between the gas phase and the wood component is not achieved during hot-pressing.This work was funded by the USDA Competitive Grant Program for Forest and Rangeland Renewable Resources, Project No. 85-FSTY-9-0106 and 87-FSTY-9-0253     

失水胁迫对长白落叶松播种苗移栽期活力的影响

苗木形态、生理和活力状况是评价苗木质量的主要方面(刘勇,1999),苗木活力与成活率直接相关(Krameretal.,1979;喻方圆等,2002)。苗木起苗后经过分级、包装、贮藏和长途运输,到最终被栽植,这期间可能会受到失水、高温和低温、光照不足等异常因素的影响,导致苗木活力下降,从而直接影响移栽成活率。一些研究表明,失水是导致苗木活     

小蓬草鲜叶正己烷提取物化学组分分析

利用气质联用仪（GC-MS）对小蓬草（Conyza canadensis）鲜叶正己烷提取物化学组分进行了分析,结果表明其化学组分中右旋-柠檬烯相对含量（50.09%）最高,其次是（顺,顺,顺）-9,12,15-十八碳三烯-1-醇（15.71%）,再次是顺-3,7-二甲基-1,3,6-辛三烯（罗勒烯）（11.21%）。小蓬草鲜叶正己烷提取物化学组分主要是萜烯类化合物（占69.89%）,右旋-柠檬烯是小蓬草鲜叶正己烷提取物化学组分的主要特征成分之一。柠檬烯是香料,又是具有化感潜力的物质,小蓬草可以作为开发植物精油或植物源除草剂的植物资源,具有综合开发利用价值。     

Investigation of changes in compressed moso bamboo (<Emphasis Type="Italic">Phyllostachys pubescens</Emphasis>) after hot-press molding

In this study, molding moso bamboo strips to a curved shape using hot-press molding operation was explored. Bamboo strips with different thickness and moisture content (MC) were subjected to press molding under 120–210 °C for different time. Changes in the chemical components of bamboo were analyzed by Fourier-transform infrared spectroscopy (FTIR). Effect of MC on thermal mechanical behavior of bamboo was investigated using dynamic mechanical analysis (DMA). Results showed that the influencing degree of four variables on compression and recovery ratios decreased as: temperature?>?time?>?thickness?>?MC. Compression ratio increased and recovery ratio decreased dramatically when pressing temperature exceeded 180 °C. FTIR analysis indicated that polysaccharide (especially hemicelluloses) underwent a progressive thermal degradation during compression at 180 and 210 °C for 40 min, whereas relative content of lignin increased. DMA results showed that bamboo samples with a higher MC had a lower storage modulus value, confirmed water had a plasticizing effect. The loss factor of bamboo with higher MC (12 and 16%) exhibited two major transitions centred around 100 °C (α₁) and 50 °C (α₂), respectively. The temperature of these α transitions kept almost unchanged as moisture level increased from 12 to 16%. These findings provide fundamental information for the future preparation of curved bamboo as profiled components in engineered products.