漂白胶贮存性质的研究(一报)——漂白胶脱氯反应的研究

本文通过测定脱氯程度不同的漂白胶样品的结合氯含量、热寿命、软化点和颜色,研究了漂白胶脱氯反应的性质,结合氯含量与热寿命的关系以及软化点和颜色的变化规律。发现漂白胶的脱氯反应是一级反应,分为两段,前一段的反应常数为后一段的四倍,说明一部分氯容易脱除,而另一部分则比较难,后者留在漂白胶中对贮存性影响不大。此研究结果为解决漂白胶贮存性差这一难题提供了理论依据和基本途径。通过测定一批样品在多年存放期间热寿命的变化,证实了本研究结论的正确性。     

The T'OLCHE', a Maya system of communally managed forest belts: the causes and consequences of its disappearance

The T'OLCHE' is a protected forest belt about 10–20 m wide that runs through the Mayan landscape on the limits of the maize fields of the farmers. This study explores its traditional use and management and traces how it has changed in the last 30 years in the study village in Yucatán, Mexico. A major change is in its extent; little remains of the 10–20% of the area it occupied in the past. Two of the causes of this are identified as being a credit programme of the local bank and 1973 state legislation concerning cattle. The causes and consequences of this decline are discussed in relation with other farmer-perceived changes in overall landuse, including a fall in maize yields. The ecological roles of the T'OLCHE' are examined. It is argued that the T'OLCHE' plays an essential role in the regeneration of the fallow vegetation and in the maintenance of biological diversity. The case of the T'OLCHE' suggests the need for a diversified and politicized look on Common Property Resource Management.     

杨树材性成熟龄模型的建立及树体内幼龄材的分布

以小叶杨和北京杨的材性测定值(导管分子长度或木纤维长度或导管腔径)作为因变量,以年轮数作为自变量,建立材性成熟非线性模型,以此为依据讨论成熟龄问题,并对幼龄材在树体内的分布进行分析。导管分子长度、木纤维长度和导管腔径的成熟龄模型为应用分段回归分析方法拟合的二次方程和定数函数结合的非线性方程,方程的决定系数在0 85 7～0 991之间,并在0 1 %水平上达到显著。以导管分子长度作为材性指标,应用这个非线性模型分析的结果表明:材性成熟龄及幼龄材半径因树种、立地的灌溉条件不同存在差异。无灌溉北京杨6～1 0年达到成熟,幼龄材半径为5 2mm左右;无灌溉小叶杨2 4～2 9年达到成熟,幼龄材的半径为90mm左右;灌溉小叶杨1 3～1 5年左右达到成熟,幼龄材的半径为85mm左右。     

竹材的采集与加工方法

竹材具有明显的变异性,为了稳定产品的质量,需要统一采集和加工的方法.本文参照国标作法和国际标准（ISO）对毛竹的采集和加工方法作出统一的规定,其中包括竹材的采集地点、采集日期、采集数量、竹龄、竹材的胸径、长度、稍径、竹材的材质,以及竹材的分段方法,竹秆大小端的长径、短径、壁厚、圆度、削尖度提出具体的要求.根据统一方法加工的竹秆变异受到限制.     

粤北低山丘陵地区小红栲木材物理力学性质初步研究

对粤北山区速生树种小红栲木材的物理力学性质进行了测试，并据此分析了该木材的加工利用价值，提出了开发利用的途径     

绿秆黄槽白夹竹生物学特性的研究

绿秆黄槽白夹竹(Phyllostachys nidularia)是天然形成的园艺新品种,1989年以来,对其生长发育特性以及与环境条件的关系进行了研究,揭示了它的“地下茎—笋—幼竹—成竹”的生长规律以及出笋和退笋的特点,为制订科学的培育技术措施提供依据。     

The scope for reconciling public good and private forestry in the United Kingdom

The nature of private forestry in the UK as an economic activity is changing, with increasing ‘public good’ demands being placed on forest owners, with or without compensation from government. Although the motives for owning woodland are weakly researched, it is evident that amenity and recreational interests rather than formal productive economic activity are a major force in influencing woodland purchase and may well be a dominant force in woodland management over many parts of the UK. Recent research suggests a need for recognition of the high value of the public goods and, in particular, recognition of their high levels of spatial variability, whilst recognising that the public good — private good dualism is an oversimplification of the actual situation. New policy instruments are currently being implemented in various parts of the UK by devolved governments, and their capacity to both remediate market failure and address the needs of forest owners is considered. Their voluntary character and the preferences of forest owners may seriously constrain the optimal delivery of public goods. Further, existing policy instruments may be seen as insufficiently geographically targeted to areas where the greatest social benefits could be anticipated from policy-induced improvements in public good values.     

红松幼龄材与成熟材力学性质的差异

本文研究了人工林和天然林红松幼龄材与成熟材力学性质的差异.结果显示,成熟材的所有力学性质均高于幼龄材.幼龄材与成熟材的抗弯弹性模量差异在人工林红松中达0.01水平显著,天然林红松也达到0.01水平显著;人工林红松抗弯强度和弦向横纹抗压强度差异达0.05水平显著.抗弯强度、顺纹抗压强度、横切面硬度和弦向横纹抗压强度4项指标的差异达0.05水平显著.     

关注林权:中国集体林政策研究国际研讨会综述

公共资源面对的挑战、风险与机遇受到国际社会的关注。文章以“国际公共资源研究协会第十届大会”为背景,对中国集体林研究课题的成果、相关国际会议内容及专家发言作了介绍。研究成果主要形成8个专题报告,国际会议分“中国集体林政策和法律框架的总体回顾”和“中国集体林与生态保护、公司 社区模式”两个部分展开,并形成了5点结论。     

杉木连栽林地土壤微生物区系及其生化特性和理化性质的研究

选择立地坏境条件相同的杉木连栽与头栽林地，进行土壤微生物，酶活性及理化性质的分析。研究表明，杉木连栽林地土壤微生物总数下降２３．３５％，其中细菌、放线菌分别下降２４．７９％和３４．０４％，真菌增加１０．３９％微生物主要生理类群氨化细菌、纤维素分解菌、好气固氮菌、微嗜氮菌分别下降３６．６０％、１４．２４％、５６．５６％和２５．８１％，厌气固氮菌增加４６．１５％．连栽林地土壤的脲酶、转化酶、过氧化氢酶的活性明显低于头栽土壤、多酚氧化酶则相反。在０－４０ｃｍ土层中．同于连栽引起土壤容重增加２．５９％、毛管孔隙、毛管含水量、田间持水量和自然含水量分别下降８．４６％、１１．０４％、１１．７８％和７．０８％，土壤有机质、Ｎ、Ｐ全量分别下降１６．６１％、１２．７５％和２１．４９％．Ｎ、Ｐ、Ｋ速效养分含量分别下降２０．０８％、８．７８％和２４．８５％．因而提出营造混交林，发展林下植被，停止或减少炼山和全垦以及增加肥料投入等技术对策。以防止连栽引起的地力衰退。