云南松低质低效林的成因及其分类

低质低效林的成因和分类是对其林分作出评价和改造的基础。在从生态学和森林培育学的角度出发，提出低质低效林概念的前提下，结合恢复生态学对低质低效林的定义，分析了云南松低质低效林的自然和非自然（人为）成因，结合起源并采用其生态公益林和用材林的功能的分类方法对云南松低质低效林进行了宏观的分类，为其低质低效林的评价和改造、更新提供了依据。     

江西省赣州市低质低效林成因与特征分析

从历史、立地、粗放经营及自然灾害等方面分析了赣州市低质低效林形成的原因,并根据森林资源调查结果,分析、总结了现有低质低效林的几大特征,以期为实施低质低效林改造提供理论依据。     

低质低效林改造经营项目的示范作用研究

分析通北林业局低质低效林现状,介绍主要采伐造林技术措施,阐述低质低效林改造经营的示范作用.     

长江中上游低质低效次生栎林的分类与评价

对林分的生长过程、形成原因和功能特征进行了分析 ,建立了栎类低质低效林综合等级的判别函数 ,将林分划分为四种类型 :极低质低效型、生长潜力型、低质型、综合低质低效型。对林分立地因子的逐步回归分析表明 ,影响栎林生长的主导立地因子依次为海拔、土层厚度和坡向 ,它们的组合可以构成不同的立地条件类型。根据对各等级的林分生长过程及其立地特征的分析 ,提出了划分栎类低质低效林的技术参数标准     

辽西北地区杨树低质低效林成因分析及对策

辽西北地区杨树低质低效林的大面积产生严重阻碍了林业的可持续发展,本文从生态学和森林培育学的角度出发,阐述了本地区杨树低质低效林现状,分析了自然因素、人为干扰等导致低质低效林形成的主要原因,根据多年的生产实践,提出了几种相应的技术措施以及改造过程中需要注意的一些问题。为现有杨树低质低效林改造提供了可靠的理论依据。     

低效林改造研究综述

低效林的大面积产生严重阻碍了林业的可持续发展。文中介绍了低效林的概念, 分析了自然因素、人为干扰等导致低效林形成的主要原因, 将低效林划分为低效防护林和低质低产林, 提出一系列低效林评判标准, 讨论了补植补播、调整改造、封育改造、效应带改造等主要的低效林改造方法, 最后指出低效林改造过程中需要注意的一些问题。     

福建省低质低效红树林类型划分及改造技术研究

由于生物入侵、人为破坏、海洋污染、病虫危害等原因,福建沿海的红树林面积呈下降态势,已有的红树林也出现了不同程度的衰退现象,林分质量下降,形成低质低效林分,其生态功能及经济价值不能得到充分发挥。文章根据福建省目前低质低效红树林的实际状况和形成原因,将低质低效红树林划分为:低生长量类型、稀疏类型、病虫危害类型、生物入侵类型、老龄林类型等5种类型。再运用生态学原理和方法,提出了每个类型相应的改造技术。     

汪清地区4种林分经营模式效果分析

本研究在汪清林业局选定4块样板林,分别对采育林后续经营、低质低效林改造、红松果材林培育、珍贵树种大径级材林培育4种经营模式进行检测和分析.结果表明:采育林后续经营样地平均胸径增长量比对照高0.23 cm,公顷蓄积增长量高3.70 m3,平均年生长量高1.85 m3;低质低效林改造经营样地平均胸径增长量比对照高0.20 ...     

辽西地区水土保持林低价成因及早期诊断技术

本文主要对辽西地区衰弱低质水土保持林的成因进行了分析，根据调查结果和试验提出了低产、低质、低效林诊断技术。并确定了改造原则、改造对象及改造后达到的目标，制定了相应的技术措施。为改造现有低价油松水土保持林提供了理论依据。     

谈南岔林业局低质低效林改造项目

通过对低质低效林改造经营,探索黑龙江省南岔林业局森林经营的新模式,以促进森林资源管理工作不断发展。     

南斯拉夫杨柳树育种的成就和经验

南斯拉夫共有杨柳树林地15万公顷,仅占森林面积的1.5%,但其木材产量却占全国木材总产量的8%。杨木产量由1950年的10立方米,提高到1985年的120万立方米,增加了11倍,成为当今国际杨树委员会的重要成员国之一。该国杨树发展速度之所以快,与其有一支稳定的科研队伍密切相关。本文较详细地介绍了南斯拉夫杨树育种的成就和经验,并结合我国的实际情况,提出了作者的看法和建议。     

美洲黑杨及其杂种在世界和我国杨树栽培中的地位与作用

本文介绍了美洲黑杨的天然分布, 生长状况。西欧各国对其珍贵基因资源的重视和利用, 我国引种美洲黑杨的现状及其作用等, 并对我国进一步利用美洲黑杨的基因资源, 促进我国杨树栽培的发展提出了一些看法。     

甘孜州造林绿化的难点与对策

由于特殊的地理和气候特征。使甘孜州高丘区阳坡，半阳坡以及金沙江，雅砻江，大渡河等“两江-河”河谷及其干流的绿化成为全州，全省，全国乃至全世界造林难题之一。目前甘孜州造林已经由立地条件较好的深沟采伐迹地更新全面转向上述难造林地区。通过多年的摸索。认为甘孜州造林要依靠科技，充分挖掘，利用州内丰富多样的植物资源，从解决四大问题入手，一是绿化思路（先灌，草绿化覆盖，后乔，灌结合造林；突破常规的投入和设计，实行稀树造林，宽带造林和多种围栏造林）的突破与创新，二是造林树草种（乡土地草种的选择和全光照营养袋培育雨季造林）选育，三是造林后期管护（落实专人，村组农户，专业队），四是进一步密切造林本身与广大农牧民增收的关系（发展名特优干果，地道药材的人工，半人工抚育和种植，造林绿化与环境美化，香化，服务生态旅游事业），逐步解决林牧矛盾，林农问题，不断提升林业在社会，经济发展中的地位和作用。     

西部大开发与农林人力资源

实施西部大开发,再造祖国秀美山川,是以江泽民同志为核心的党的第三代领导集体高举邓小平理论伟大旗帜,把握历史,面向未来,高瞻远瞩,审时度势,总揽全局,站在跨世纪我国经济发展的战略高度作出的决策,是加快西部地区经济发展,逐步缩小东西部地区差距,确保国家长治久安,人民安居乐业,促进共同繁荣,实现中华民族伟大复兴的重要举措。在实施西部大开发中,人力资源的开发与利用至关重要。     

Linearity and non-linearity in mechano-sorptive creep of softwood in compression and bending

Summary Non-linearity of softwood in axial mechano-sorptive creep during moisture cycling can be characterised as departure from linear behaviour. Linear behaviour is shown by experimental measurement to be a gradual approach to a creep limit with exponentially decreasing increments of compliance, J_i, per moisture cycle, when tested under a constant stress. On the other hand, when the stress is progressively increased by a small increment after each moisture cycle, the compliance increments will progressively increase, having a value of , where n is the cycle number. By subtracting one compliance increment from the succeeding one, the value of J_i can be obtained. Analysis of experimental results in bending tension and compression showed that the compression test pieces departed from linearity at total strains around 0.14% to 0.15%, the bending test pieces showed slight evidence of non-linearity at about the same strain, whilst the tensile pieces were approximately linear up to 0.18% strain.This project was supported by the U.K. Science and Engineering Research Council and by the European Commission     

内蒙古湿地资源保护恢复中的问题及对策

文章简要地分析了围垦湖沼、上游截流、过度利用及工艺技术落后等人为因素对湿地资源的破坏情况与负面影响,给人们赖以生存的湿地生态环境带来严重的不可逆转的后果,并有针对性地提出了几点建议。     

米东区森林病虫害防治工作存在的问题及对策

森林病虫害防治是国家减灾工程的重要组成部分,对保护森林资源,改善生态环境,促进国民经济和社会可持续发展具有十分重要的意义。     

Land and forests in the Anthropocene: Trends and outlooks in Asia

Forest cover change is one of the defining contemporary environmental changes that validate the proposition of the Anthropocene narrative. Forest transition is a well-recognized global phenomenon, which has been studied and explained in well elaborated forest transition theory. Forest transition has been observed in over 30 countries, and it has been a trend in multiple countries in Asia. Forest transition is most relevant for the Anthropocene narrative, as it suggests that forest cover decline may eventually be followed by a forest cover increase at the global scale. The paper reviews evidence of forest transition in eight Asian countries and juxtaposes this with global forest cover trends. In Asia countries like China, India, Japan, Philippines, South Korea, and Japan and Vietnam are among the countries that have experienced an increase in the area under some kind of tree cover. Complex interplays of forest cover, population growth, economic development, demand for forest goods and services and governance effectiveness are the driving forces of forest transition. While it is not possible to extrapolate Asia's forest transition to the global scale, the Asian experience makes it possible to make statements on possible global forest cover scenarios. Ultimately, forest transition theory in general, and the experience of forest transition in Asia also support the concept and related narrative of the Anthropocene.     

Considering and comparing regeneration in natural and man-made stands in northern Iran

In this study the regeneration diversity of Syahkal forests afforestated and natural stands in north of Iran was studied and compared from the point of view of evenness and diversity index.In order to accomplish this study two natural and man-made stands that almost are located in the same height above the sea level were chosen.The area of each stand was 30 ha and the inventory was done by the random-systematic method with a 5R land measurement(500 m2)selected.Also,in order to study the regeneration in the center of each sample piece 125 square meters micro plots were formed.The results show that regeneration diversity index in natural stands is more than that in man-made stands which in this case Mc-Arthur index with 2.41 has the most amount while Simpson index with 0.543 has the least amount.But the evenness indexes in man-made stands are more than that in natural stand which the main reason is the purity of the man-made stand.