黄连木种子小蜂的研究进展

黄连木种子小蜂是黄连木的最主要害虫。该文对各地有关黄连木种子小蜂发生与危害特点、生活史、生长发育与环境的关系以及测报与防治方面的研究进展情况进行了总结。     

云南省黄胸木蠹蛾的危险性评估

黄胸木蠹蛾是多种阔叶树种的重要蛀干害虫。为正确认识云南省黄胸木蠹蛾对林木所造成危害的危险性,加强管理,有效地控制该虫的危害和防止其进一步扩散蔓延,采用有害生物危险性分析(Pest R isk Analysis)的方法,对黄胸木蠹蛾在云南省的危险性进行了系统的定性与定量分析。通过综合评估,认为黄胸木蠹蛾在云南省属于中度危险性的森林有害生物。     

单叶蔓荆对滨海沙地土壤养分和木麻黄生长的影响

通过对比分析蔓荆地、非蔓荆地主要养分、木麻黄生长量及蔓荆林地小气候变化特点的试验研究表明 ,单叶蔓荆能促进木麻黄生长 ,可作为海滨沙地、风口地段固沙造林的先锋植被     

西双版纳望天树林的群落组成和结构特征研究

利用1992~1993年在西双版纳自然保护区的勐腊县补蚌片区建立的5块望天树林固定样地的观测资料,从物种组成、科属区系特征、水平布局和垂直布局方面对该群落的组成和结构特征进行了研究,采用α多样性指数及联合熵H(X,Y)分析了望天树林群落结构的多样性;采用β多样性指数比较了样地间的多样性。结果表明:西双版纳望天树林物种相当丰富,在5块50 m×50 m的固定样地内计有种子植物68科176属380种。该群落中热带科有57科,占89.1%,热带属有163属,占92.6%,反映出其强烈的热带性质。根据树高的分布情况,将该群落的地上垂直结构分为5层,即计有乔木3层,灌木层和草本层。而对群落内物种的水平分布格局所进行的检测结果显示,所选择的3个主要树种(望天树、木奶果、假海桐)在5块固定样地内均为典型的集群分布。联合熵分析表明,其群落结构的多样性指数为15.800 8~21.005 3。     

硫素的营养诊断及对土壤、环境的影响

本文对硫素的营养诊断及硫肥对土壤、环境的影响作了系统的综述。内容主要包括硫肥的种类和性质、作物硫素营养诊断方法、硫肥的营养作用、土壤中硫的形态和作用以及硫肥对大气、水体的危害,并提出了施用硫肥时应注意的问题。     

智能建筑系统的构成及造价确定

智能建筑应能提供安全、舒适、快捷的优质服务,有一个有利于提高工作效率、激发人的创造性的环境.智能建筑是楼宇自动化系统、通信自动化系统和办公自动化系统三者通过结构化综合布线系统和计算机网络技术的有机集成,其中建筑环境是智能建筑的支持平台.     

Understory plant communities of boreal mixedwood forests in western Canada: Natural patterns and response to variable-retention harvesting

We examined patterns of variation in richness, diversity, and composition of understory vascular plant communities in mixedwood boreal forests of varying composition (broadleaf, mixedwood, conifer) in Alberta, Canada, before and for 2 years following variable-retention harvesting (clearcut, 20 and 75% dispersed green tree retention, control). Broadleaf-dominated forests differed from mixedwood or conifer-dominated forests in that they had greater canopy cover, litter depth, soil nitrogen, warmer soils, as well as greater shrub cover, herb and shrub richness and diversity (plot scale). In contrast, conifer, and to a lesser extent mixedwood, forest had greater β diversity than broadleaf forest. Overall, mixedwood and conifer forests were similar to one another, both differed from broadleaf forest. Several species were found to be significant indicators of broadleaf forest but most of these also occurred in the other forest types. Understory composition was related to canopy composition and edaphic conditions. Variable-retention harvesting had little effect on understory cover, richness, or diversity but resulted in reduced richness and β diversity at a larger scale. The clearcut and 20% treatments affected composition in all forest types. Early successional species and those common in disturbed sites were indicators of harvesting while evergreen, shade-tolerant understory herbs were indicators of the control forest and 75% retention harvest. We conclude that it is important to maintain a range of variation in canopy composition of mixedwood forests in order to conserve the associated understory communities. The presence of conifers in these forests has a particularly important influence on understory communities. The threshold for a lifeboat effect of variable-retention harvesting is between 20 and 75% retention. Examination of richness and β diversity at a variety of scales can provide interesting information on effects of harvesting on spatial reorganization and homogenization of understory plant communities.     

基于有限元分析方法的连杆螺栓改进设计

根据生产企业的实际情况,提出了在应力集中严重的连杆螺栓头部与杆部过渡圆弧处进行局部滚压的改进措施,并通过有限元分析手段,得出当滚压力达到20kN时,就能使连杆螺栓在不改变原结构的前提下满足疲劳寿命的要求。     

冰雪灾后粤北山区受损杉木萌条生长规律研究

以位于粤北山区天井山林场的杉木（Cunninghamia lanceolata）人工林中的受损杉木为研究对象,研究了2008年初冰雪灾害后1年内受损杉木的恢复和更新情况。采用标准地调查法,选取4种不同类型受损杉木的标准木（类型Ⅰ：断干高在原树高的1/3内;类型Ⅱ：断干高在原树高的1/3~2/3处;类型Ⅲ：断干高在原树高的2/3以上;类型Ⅳ：倒伏）,监测其自2008年11月—2009年11月期间的萌条高和基径的月生长动态。结果表明：冰雪灾害后的一年内,受损杉木萌条高生长的旺盛期为5—9月份,而基径生长总体呈现初期生长增加明显,后期增速逐渐缓慢的特点。林分密度与受损杉木萌条的生长关系密切,需在灾后杉木人工林重建时给予重点关注。受损Ⅲ型和受损Ⅳ型杉木萌条生长较好,但综合考虑生长和成材效果,建议保留受损Ⅲ型,伐掉受损杉木Ⅰ型、Ⅱ型和Ⅳ型。