Interface Characteristics of Wood-hybrid Composites

In recent years, many researchers all over the worldhave used inorganic compounds to improve theproperties of wood, for inorganic compounds are cheapand can be obtained easily. Furthermore, they havegood functions and are environmental-friendly if theyare well controlled (Chen Zhilin, 2003). Wood-hybridcomposite is a kind of organic-inorganic hybridmaterial(OIH). OIH means that organicmacromolecule material and inorganic material becomea mixed in molecule level to get excellent capabilities…     

Discussion on Private Forestry Development in China

1 HISTORICAL PROCESS ANDPRESENT SITUATION ON PRIVATEFORESTRY IN CHINABefore 1978, all the private sectors were bannedto own forest tenure in China. At that time, forestwas managed by state-run forest farms, state-runforestry industry bureaus or collectives. When thereform and opening-up policy was initiated inChina, with the implementation of HouseholdResponsibility System (HRS) in rural areas, privatesectors began to participate in forestry. In March1981, the State…     

Assessing Threats and Setting Conservation Priorities for Plant Species between Forest and Meadow Ecotone in Sanjiangyuan Nature Reserve, China

INTRODUCTIONA large number of nature resources have fosteredhuman beings in the world. However, during the lastfew decades these nature resources and biodiversitywere subjected to various anthropogenic pressuressuch as plantation, deforestation, construction ofhydro-electric project, overgrazing and exploitation andother developmental activities (He Youjun, et al, 2004b;Li Ang, et al, 2002; Swamy, et al, 2000). In order toprotect environment and biodiversity, we have to facethe challenge…     

Study on Impacts of pH Value on Paulownia Wood Color

INTRODUCTIONPaulownia is one of important species with fastgrowth and high yield oriented to industry uses inChina, paulownia wood is widely used in furniture-making, decorating materials, musical instrumentsmanufacture (Jiang Jianping 1990), etc. Brown orblack stain often appears on the surface of paulowniawood during processing and using. Discolorationseriously affects paulownia utilization, and it cancause huge loss due to low grade and price causedby stain (Cheng Junqing 1983a, 1983b…     

Genetic and Environmental Variations in Leaf Oils of Six Eucalypt Species

Chemical analyses were conducted with leave oils of Eucalyptus smithii, E. bakeri, E. polybractea, E. dives, E. radiata and E. macarthurii vvhich were introduced to southwestern China from Australia. It was found that the leaf oils of E. smithii, E. bakeri and E. polybractea contained 81-90% of 1 ,8-cineole, and E. dives and E. radiata contained higher a-phelandrene and piperitone. There vvere significant inter- and intraspeciflc variations in leaf oil yield, it also varied with seasons in vvhich leaves vvere harvested. The results suggested that more research should be undertaken to identify genotypes with high-yield of leaf oils. These species could be applied to develop community forestry.     

一种森林抽样样本容量表

本文介绍一种森林抽样样本容量表。简单随机抽样用迭代公式计算样本容量,该式将样本容量表示为估计的变动系数和规定容许相对抽样误差的函数。迭代法在林业中用于计算样本容量时被证明并非都是收敛的。这里介绍一种修正的迭代方案,并编成数表来使用。     

桉树的无性繁殖

扦插是林木无性繁殖较喜用的,因能从单株获得大量的插条苗,可避免嫁接的不亲和性,同时,插条比其他无性繁殖方法和压条、嫁接等的材料的获得要便利。实生苗茎部插条桉树实生苗扦插容易形成根系,Gior-dano于1961年用赤桉一年生苗基部(0—30厘米)扦插,其生根率在60％以上。通常插条需要3个月以上才能生根。但葡萄桉在同     

亚热带幼龄果树叶片的矿质营养诊断

采用营养诊断的方法,可以更精确地确定亚热带果树对肥料的需要。把分析叶片中的化学成份与树体的生长和产量的相关指标作为诊断的依据,就可以比较清楚地说明亚热带果树不同发育阶段所需要的营养元素、诊断的对象是柠檬、石榴和核桃无机态营养物质的含有程度。     

Dielectric properties of copper-ethanolamine treated Chinese fir (Cunninghamia lanceolata Hook.)

In order to clarify the interaction between copper and wood substances in wood treated with copper containing water-borne wood preservatives, the dielectric constant ε′ and dielectric loss factor ε″ of untreated wood and wood treated with four concentration levels of copper-ethanolamine (Cu-EA) solutions were determined within a temperature range from –100 to 40°C and a frequency range from 100 to 1 MHz. Three dielectric relaxation processes were observed in the ε″ spectrum; among them R-I is based on the reorientation of methylol groups in the amorphous region of wood cell walls and R-II is related to wood extractives. R-III appeared in Cu-EA treated wood, and its magnitude decreases with the concentration of Cu-EA solutions used in this experiment. This relaxation process was considered to be based on the reorientation of copper-ethanolamine-wood complexes in wood cell walls. At low copper retention, the hydrogen in the complex can form hydrogen bonding with adjacent hydroxyl groups, which results in a strong bonding state between copper and wood; at high copper retention, the numerous copper-ethanolamine complexes not only hinder them from forming hydrogen bonding with adjacent wood molecules due to steric hindrance, but also weaken the interaction between wood molecules themselves, which corresponds to reducing ε″ values of both R-I and R-III processes. The results explain the fact of in-creasing copper leaching in wood treated with high concentration copper-based water-borne preservatives.     

中国南部热带植物区系的特点与亲缘

中国南部热带植物区系主要以云南南部、广西西南部和海南热带植物区系为代表 .该文简要分析了它们植物区系的组成特征和地理成分 ,比较研究了云南南部和海南热带植物区系与东南亚的马来半岛和文莱热带植物区系的关系 ,得出以下结论 :(1)中国南部植物区系主要由热带植物区系成分组成 ,热带分布的科和属分别占总科和属数的 6 0 %和 80 %多 ,在热带分布属中 ,又具体以热带亚洲成分占优势 ,显示该植物区系是热带性质的植物区系 ,具有热带亚洲亲缘 ;(2 )中国南部热带植物区系中多于 70 %的科和多于 5 0 %的属与马来西亚植物区系共有 ,并且其优势科中大多数也为马来西亚植物区系的优势科 ,意味着在植物区系分区上它属于热带亚洲或印度 马来西亚植物区系的一部分 ;(3)由于位于东南亚热带北缘 ,中国南部热带植物区系中以边缘热带成分为主 ,是印度 马来西亚植物区系的热带北缘类型 ;(4)中国南部植物区系的热带亚洲亲缘可以从东南亚的地质演化历史解释