Effects of extraneous substances, wood density and interlocked grain on fiber saturation point of hardwoods

Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP.     

毛环竹笋用林生物量结构调查分析

通过对毛环竹林分、单株生物量及其结构特征调查分析,结果表明:毛环竹林分生物量在一定范围内随着密度的提高而增大,在密度为10800～12900株·hm-2时生物量最大,地上部分可达到50t·hm-2以上,地下部分可达到30t·hm-2以上。各器官生物量分配为:地上部分生物量秆>枝>叶,其比例大致是6∶3∶2或2∶1∶1;地上部分>地下部分,其比例变化幅度在1 183～1 784之间。毛环竹单株生物量与胸径、竹高呈正相关,在生产实践中可用模型W=aDbHc进行估测,其精度达95%以上。     

云南松蠹害林分蠹害木清理技术

根据多年的综合防治试验研究结果，提出了云南松蠹害林分蠹害木的清理技术。 包括：(1)蠹害林分受重程度划分；(2)蠹害木分级标准；(3)蠹害木的清理技术。阐明了蠹 害木清理的时间、次数、对象、顺序、方法及清理后的处理等技术措施。对于实施以 营林措施为基础的蠹害综合防治技术，有效地控制林间小蠹虫种群密度均具有重要作用。     

韶兴市园林及经济林木的介壳虫名录初报

初步查明绍兴 3 4属 48种介壳虫为害 65种植物寄主。其中为害裸子植物苏铁科Cycadaceae、罗汉松科 Podocarpaceae、粗榧科 Cephalotaxaceae、松科 Pinaceae、柏科 Cup-pressaceae的有 1 6属 2 0种 ;为害被子植物中单子叶植物的禾本科 Gramineae、百合科L iliaceae、棕榈科 Palmae的有 7属 1 0种 ;为害双子叶植物的榆科 Ulmaceae、山毛榉科Fagaceae、桑科 Moraceae等 2 1科植物的有 2 1属 2 8种     

关于发展宁南山区林草一体化产业的刍议

引入用国内外大量成功的实践经验和著名科学家的观点论述了发展林草一体化产业的意义和功效。认为，走林草一体化道路，发展林草一体化产业，是解决山区林牧矛盾，消除由此而产生的社会不稳定因素，制止滥垦乱伐，破坏生态植被，实现林业，畜牧业统一协调发展的高层次，高效益循环的必然途径，提出了宁夏南部山区发展林草一体化产业需要遵循的原则，适宜的模式及应采取的措施。     

安徽主要商品材性质及用途的微机检索研究

从安徽重要商品木材、珍稀和待开发树种中挑选１３９种针、阔叶材。阔叶树材根据ＩＡＷＡ国际标准编制特征数据盘,针叶树材自行创制特征编码标准,经检测效果满意。本研究在国内外木材学领域内首次使用ＦＯＸＢＡＳＥ＋关系数据库,可按科、种名,部分解剖特征或用途检索其他重要信息,也可对其自身进行保护、修改或增删,实现了木材鉴定的微机化、自动化。     

Effects of extraneous substances,wood density and interlocked grain on fiber saturation point of hardwoods

Abstract

Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP.     

Chemical characteristics of woods from several Chilean native forest species and their relationship with nanomechanical cell properties

The objective of this research was to study the chemical and nanomechanical characteristics of native woods grown in southern Chile region. The species analysed were Drimys winteri, Laureliopsis philippiana, Aextoxicon puctatum, Nothofagus alpina, Nothofagus dombeyi, Laurelia sempervirens, Austrocedrus chilensis and Fitzroya cupressoides. The samples were collected from the regions of Biobío (37° S, 73° W), Araucanía (37° S, 71° W) and Los Lagos (40° S, 73° W). Chemical analysis reported that glucan content of native woods was between 39% and 44% and lignin content between 28% and 35%. The nanomechanical properties analysed in the secondary cell wall (S2 layer) and middle lamella (ML) were elastic modulus (E), hardness (H) and ductility ratio (E/H). Values for E_S2 were between 12.0 and 15.4 GPa and for E_ML between 4.3 and 6.6 GPa. Hardness values were similar in ML and S2 (≈0.3 GPa). The compilation of results showed high correlations between E_S2 and carbohydrate content (r = 0.80), between E_S2 and hemicellulose content (r = 0.89), and between H_S2 and lignin content (r = 0.88).     

村落风水林休闲游憩开发

在对村落风水林的休闲游憩价值分析的基础上,提出对风水林进行景观生态改造、配套乡村自然休闲设施以及组织林下空间休闲活动等村落风水林休闲游憩开发建议。     

河北省速生林与粮食生产研究

2002年启动的速生丰产用材林基地建设工程是中国第六大林业工程,工程实施近10年来究竟对粮食生产有无影响,影响程度多大?基于此问题,选取环绕京津、地理位置尤为重要的河北省作为研究区,基于土地利用的角度,对河北省速生林种植面积、粮食播种面积和产量等进行了分析.研究结果表明,河北省及各市速生林种植的时间、空间差异非常悬殊,但对粮食播种面积影响很小,对粮食产量没有影响.鉴于速生林改善生态环境的良好效果和产生的巨大经济效益,今后在河北省条件适宜的地区可继续种植,但要尽量少占耕地,减少对粮食生产的影响.