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.     

绿竹笋期生物学特性观察研究

连续三年观察研究表明:(1)绿竹秆基笋目数量在4～10个之间,笋目萌动始于二月底,总萌动率79.3％,发笋数占萌动数的73.0％。(2)绿竹笋期长达5个月,可分为初期、盛期、递减期和末期四个阶段,盛期出笋株数和重量分别占72.0％和75.9％,比其他竹种更为集中。(3)绿竹一年生母竹发笋量占总重量的92.1％,二年生占7.9％。(4)竹丛的总出笋数和重量与座底竹数量具有正相关关系,r_1=0.7582,r_2=0.7279。株平均出笋数和重量与座底竹数量具有负相关关系,r_3=-0.6124,r_4=-0.6418。(5)绿竹幼竹高生长历时85天左右,总生长量达950cm,日均生长量11.2cm,日最大生长量24cm。幼竹夜间生长量比白天快1.7倍。     

Plantation Forests for Sustainable Wood Supply and Development in China

With the implementation of Natural Forests Protection Program, wood resource base in China is shifting from naturally grown forests to plantation forests. This paper reviews: 1) The evolution of Chinese decade-long reforestation program and its contribution to sustainable wood supply and development, and 2) impacts of "China's Natural Forest Protection Program and " Fast-Growing and High-Yield Plantation Program in China " on China's wood supply and sustainability. In addition, this paper highlights Chinese national researches on the integrated intensive management and utilization of the plantation resource.     

系统收获表研究的概念和功能(英文)

传统收获表是指某一树种在特定地区和管理体系下，以立地条件和年龄为变量描述林分平均生长过程的数表．林分密度管理图是根据林分密度效果编制的可预测林分平均收获的图．通过与传统收获表和林分密度管理图的概观比较和探讨，该文系统地阐述了系统收获表的概念和功能．系统收获表的基本特点是为预测现实林分在不同立地条件和管理体系下生长过程的计算机程序．因此，系统收获表能描述在多维变量（如年龄、立地条件、林分密度、胸径和树高）条件下的现实林分和单木的无数生长过程     

试论川西地区实施防护林体系建设的必要性

川西地区处于长江上游及其源头,是重要的水源涵养区,由于森林集中过伐,植被遭到破坏,森林的涵养水源和保持水土的功能削弱。为恢复川西地区绿色森林屏障,笔者提出将川西地区纳入防护林体系工程造林,以恢复和增加森林植被,形成合理的林种、树种结构,发挥涵水保土和改善生态环境的作用,使川西地区实现集生态、经济、社会效益为一体,协调发展的生态林业基地。     

油松容器苗施肥的研究

本文根据研究结果论述了油松容器苗营养土中掺合尿素的最适量,一定出圃规格油松容器苗的施肥量以及施肥量的计算方法。同时还论述了1年生油松容器苗有关的化学营养诊断指标。     

杉木间伐小径材材性试验研究

杉木间伐小径材材性试验结果与成材杉木比较:密度小,晚材率较低,生长较快,吸水性较强;材质为未成熟幼林材种,物理性质较差,力学强度有所降低,作为建筑结构用材时,在设计与施工中必须注意到其强度的降低,采取必要的措施。杉木间伐小径材纤维长度与成材相似,纤维宽度略宽、纤维长宽比值略小,但尚为良好的纤维原料。     

威布尔(Weibull)空间分布型模型的抽样式研究

本文首次运用威布尔分布于昆虫空间分布型的抽样式研究中,经推导得出符合威布尔分布型模型的理论抽样式和序贯抽样式,具体给出了惠安县马尾松毛虫种群的抽样规则,旨在为实际应用和进一步研究提供科学依据。     

Forest Fires and Prevention Strategies in Northwestern Region of China

The paper described the natural conditions and forest types in Northwestern Region of China. Most forests in the region are distributed in subalpine areas. It is important to protect the existent forests in the region for maintaining ecological balance. According to the statistics results of 1991~2000, the paper analyzes the forest fires distribution and fire severity. Annually the numbers of forest fires range from 52 to 240. The incidence rate of forest fires in Northwestern Region is under 0.33 per ten thousand ha. There are 0.67-64.4 ha burned area per ten thousand ha forest. The main reasons for forest fires lie in the dry weather conditions, many firebrands, and high fuel loading. The strategies of fire management in the region are to stress the fire education in forest regions, strength the firebrands' management, emphasize the fuel management, and improve the fire monitoring and fire control ability.     

茶梢蛾幼虫空间分布及其抽样技术

对茶梢蛾幼虫的空间分布型及抽样技术的研究结果表明,幼虫为普通聚集分布,其基本成分是面积为一株油茶大小的个体群,个体间相互吸引。调查时以棋盘式取样为佳。根据空间分布型分析,计算出序贯抽样模型为:最适理论抽样数模型为: