测定立木材积的近似形点法

提出了在形点上、下一定区间内，任选一测点测定立木材积的方法，给出了计算公式，验证了测定结果，分析了误差机制，得出了立木干形指数ｒ确定近似形点的许可区间△ｈ。尖削的阔叶树种的许可区间为０～５０ｃｍ。中庸的针叶树种的许可区间为０～１００ｃｍ。     

“化工原理”教学中学生工程技术素养的培养与强化

工程技术素养是工科大学生最重要的素质之一，也是大学生未来工作能力的基础。该文结合多年的“化工原理”教学改革的探索和实践，从经济性观念、处理化学工程问题的数学模型法和近似处理法、工程观念、实验能力等方面阐述了如何培养学生的工程技术素养。实践表明，这些做法能够培养学生的工程技术素养，提高学生的综合素质。     

改进的密度泛函理论在活性炭孔径分布的应用

为提高活性炭孔径分布模型的计算精度,以4种基于不同方法求解剩余自由能的密度泛函理论方法,计算孔径宽度在0.65~5 nm的狭缝孔对3种气体(CH_4,N_2和CO_2)在压力为0.2~2 MPa,温度为298 K下的过剩吸附量,发现4种方法对CH_4和N_2气体计算结果相近,但对于CO_2气体,平均场近似法和泛函展开法的结果比加权密度近似法的结果偏低,说明对于CO_2气体,在自由能的计算中相互作用项的影响不可忽略,并且,经矩阵条件数分析,确定加权密度近似法WDA(Yu)在计算的精度和稳定性上都更适用于孔径分布地建立。使用6种数值方法对3种活性炭的3种气体吸附等温线拟合,结果表明,平均偏差均小于5%,且所建立的活性炭孔径分布模型可以对样品的微观结构进行半定量地比较。     

多形白僵菌与布氏虫草近似种的关系

报道了采于安徽霍山的布氏虫草近似种Ｃｏｒｄｙｃｅｐｓ ｂｒｏｎｇｎｉａｒｔｉｉ Ｓｈｉｍａｚｕ ａｆｆ．。通过子囊孢子的微循环产孢证实其无性型多形白僵菌Ｂｅａｕｖｅｒｉａ ａｍｏｒｐｈａ Ｓａｍｓｏｎ，并成功诱发出有性型子实体。     

园林新树种——东方衫

东方杉与近似种墨西哥落羽杉都是杉科（Taxodiaceae）树种，通过对这两个树种形态特征及树种生态习性的比较、分析，为合理应用提供依据。     

建筑结构近似非线性反应分析方法综述

本文较详细地总结和评述了5种建筑结构的近似非线性反应分析方法。通过总结和评述,可系统地了解现有这些方法的原理和过程,以供建筑结构的研究人员和设计工作者使用时参考。     

高温高压下立方二氧化铪(HfO2)的热弹性及热力学性质分析

采用基于密度泛函理论的第一性原理赝势平面波方法计算立方结构二氧化铪（HfO2）的平衡晶格常数、体积模量以及晶胞体积与晶格能量的关系曲线。结合准谐近似的德拜模型，考察了立方结构二氧化铪的体积模量随温度（0—2000K）和压力（0—100GPa）变化关系，分析了等容热容、热膨胀系数以及Grnneisen参量随温度和压力的变化规律，讨论了立方结构二氧化铪作为高温结构材料和热障涂层的可行性。     

悬链线几何参量和力学参量的计算

本文以曲线弧长1,水平距离a和端点高差h为基本量,推导出了悬链线各几何参量和力学参量的成套计算公式。考虑到增大悬链线水平距离及高差的要求,提出了四次曲线近似的计算规范。可供索道工程设计计算时参考。     

特呈岛海岸卫士——红树林

特呈岛位于广东省湛江市霞山区东南的湛江港湾内，陆地面积约360公顷。特呈原是古越语，特即地方，呈亦作情，意为和睦之地。特呈岛形状近似椭圆，岛上有7个自然村，4500多当地居民皆姓陈。据2005年湛江红树林国家级自然保护区划界调查，岛上共有红树林33.8公顷，主要分布在岛东南面的东村、     

全圆复测法

本文提出一种新的水平角观测法，该法把传统的复测法同全圆测回法结合起来，它吸取了传统方法的优点，克服了它们的缺点，因此大大地提高了测角的精度。本文论述这种方法的观测程序，它的优点及其测角精度，新法与两种传统测角法的比较，详细介绍它在测站上及三角网中的试验情况，目前都认为用6″级的经纬仪测角不能满足四等三角测量的要求，然而，首钢地质勘探队所进行的试验表明，用6″级的经纬仪采用全圆复测法测角是可以达到四等三角测量的精度要求，并且它的效率略高于全圆测回法。     

余姚地区松幽天牛发生情况及其在枯死马尾松根部分布规律的初步研究

调查了松幽天牛(Asemum amurense)在余姚地区的发生情况及其幼虫在枯死松树根内的分布规律。结果表明,松幽天牛在余姚地区1年发生1代,以幼虫在松树根内越冬。4月中旬开始化蛹,5月中旬成虫开始羽化,6月上旬成虫开始产卵,7月下旬卵开始孵化。松幽天牛在余姚地区的平均危害率达42.9%,其发生与土壤理化性质密切相关。松幽天牛幼虫在主、侧根内的分布数量差异显著,主根内的幼虫数显著多于侧根内。还依据松幽天牛的生活学特性提出了松幽天牛的防治措施     

俄罗斯联邦的森林资源及其特性

俄罗斯联邦森林资源极为丰富,在世界上占有重要地位,其森林资源本身具有地域分布的不均匀性、变动的相对稳定性、针叶树种及成过熟林蓄积的优势性十分明显。这些特点为中俄林业合作开发亚洲地区的森林资源奠定了良好的物质基础。     

蜡杨梅砧木嫁接的晚稻杨梅盐碱地栽培试验

用2种不同砧木嫁接晚稻杨梅种植于盐碱地和酸性土壤中,进行杨梅栽培试验.结果表明,两种土壤中的营养元素除速效钾盐碱土高于酸性土外,其它均低于酸性土,但两种土壤上的杨梅叶片元素含量有所不同,大量元素盐碱土稍低于酸性土,而微量元素除Cu相同外其它均高于酸性土;本接杨梅种植在盐碱地上与蜡杨梅作砧木嫁接杨梅生长相比较,本接杨梅树...     

Effects of nutrition spatial heterogeneity on root traits and carbon usage by roots of Cercis chinensis seedlings in split root rooms

In natural ecosystems, nutrition available for plants shows great spatial heterogeneity. Much is known about plant root responses to the spatial heterogeneity of nutrition, but little is known about carbon usage in roots in nutrition-deficient patches and its effect on root longevity. In this study, split-room boxes were used for culture of Cercis chinensis seedlings, and the small rooms were supplied with different nutrition levels. The number of the first-order roots in the rooms with nutrition supply was significantly higher than that in the rooms with deficient nutrition. Specific root length (SRL) of the first-order roots in the rooms with deficient nutrition reached its peak at day 64 after nutrition treatment. There was no significant SRL differences between the two order roots during the experiment. Biomass of the first-order roots in the rooms without nutrition supply was significantly less than that of the first-order roots in the rooms with nutrition supply from day 64 to 96. The total biomass of the lateral roots in the rooms without nu-trition supply decreased from day 64 to 96. The activities of the enzymes in roots in the rooms without nutrition supply increased and the activities of alkaline invertases in roots in the two sides of split box did not change significantly. The activities of the enzymes in roots in the rooms without nutrition supply increased gradually. These results suggest that nutrition spatial heterogeneity induced the changes in root traits and plants actively controlled carbon usage in roots in nutrition-deficient patches by regulating the activities of invertases and sucrose synthases, resulting in the reduction in carbon usage in the roots in nutrition-deficient patches.     

Weather and human impacts on forest fires: 100 years of fire history in two climatic regions of Switzerland

Understanding the factors driving past fire regimes is crucial in the context of global change as a basis for predicting future changes. In this study, we aimed to identify the impact of climate and human activities on fire occurrence in the most fire-prone regions of Switzerland. We considered forest fires, land use and meteorological data over the period 1904-2008 in the neighboring mountain cantons (states) of Valais and Ticino, which are characterized by distinct climatic regimes.The presence/absence of fire ignitions was analyzed using the Nesterov ignition index (as a proxy for fire weather), road density (for ignition sources), livestock density (for biomass removal), and change in forest area (for fire-prone abandoned agricultural areas).We found that fire weather played a key role in fire occurrence in both regions. Road and livestock densities had similar influences in the two cantons. However, while the increase in forest area was well correlated with fire occurrence in Ticino, no such correlation was evident in Valais, probably because land abandonment and forest cover change have been less extensive there. Our findings emphasize the non-linear nature of the relationships between fire occurrence and anthropogenic drivers, as we found thresholds above which road density was no longer correlated with fire occurrence. This implies that the projected future increase and spatial concentration of the human population may not result in a further increase in fire risk in intermediately to densely populated areas in both cantons.The driving factors behind fire activity differ slightly in the two cantons, in particular with increasing forest area enhancing fire occurrence in Ticino but not in Valais. These differences should be taken into account when assessing future fire risk, especially in Valais where the potential for an increase in the fire-prone area is still high. Fires are likely to become more frequent in a warmer climate, but future fire activity may develop differently in the two cantons. This should be taken into account when planning optimized fire prevention measures. This case study should help to better understand fire activity in highly populated regions where fire activity is still moderate but might markedly increase under a projected more fire-prone climate.     

长白落叶松人工林林隙间伐对林下更新及植物多样性的影响

2009年7月中旬,以佳木斯孟家岗林场间伐8年后的34年生长白落叶松人工纯林为对象,分析均匀间伐、大林隙和小林隙的林下更新和植物多样性。结果表明:与均匀间伐相比,林隙内出现了树高超过1.5m的胡桃楸、山杨和春榆等喜光阔叶树种,大林隙中出现树高超过2m的胡桃楸幼树;林隙内更新树种的个体密度、平均高和平均地径明显增加,大林隙尤为显著(P<0.05);林隙内木本植物的Simpson多样性指数和盖度均显著高于均匀间伐(P<0.05);与小林隙相比,大林隙内木本和草本植物盖度均显著增加(P<0.05);木本植物竞争种的重要值表现为大林隙>小林隙>均匀间伐,耐胁迫种的重要值相反(P<0.05);大林隙内1年生草本植物的重要值显著高于小林隙和均匀间伐(P<0.05),多年生草本植物则相反(P<0.05);大林隙Grime'功能群中杂草种的重要值高于小林隙和均匀间伐,耐胁迫种则相反(P<0.05);小林隙与均匀间伐的草本植物不同生活型及Grime'功能群的组成差异不明显(P>0.05);林隙间伐结合均匀间伐可以将长白落叶松人工纯林改造成长白落叶松针阔混交异龄林,较单独实施均匀间伐更有利于林下更新和植物多样性的提高,间伐林隙应...     

全国杉木家系区域试验研究

湖南省林科院先后于 1984年春、 1989年春两次参加全国杉木家系区域试验。方差分析表明 :提供家系的种子园之间以及种子园内家系之间各主要数量因子存在显著差异。对样本观测值进行标准化变换主成分分析 ,求出遗传综合指数 ,再聚类分析评价 :湖南靖州、江西赣南、广西柳州、贵州东南、福建三明、广东曲江种子园提供的家系生长有明显优势。     

保松灵防治松墨天牛的林间试验

松材线虫病 [Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle]严重威胁我国的森林资源。浙江等地每年因该病造成大量松树枯死 ,防治松材线虫病刻不容缓。当前 ,我国防治该病主要措施是清理枯死松树 ,降低媒介昆虫松墨天牛 (Monochamus alternatus Hope)密度 ,减缓病害扩散蔓延。但在风景名胜区的松林和古树名木等 ,一旦发生该病 ,仅清理死树是不够的 ,必须采取保护性措施 ,防止因病害导致大量宝贵松树枯死。在日本 ,长期以来主要措施是在松树树冠进行空中或地面喷洒杀螟松、倍硫磷、西维因等农药 ,杀灭松墨天牛成虫 ,从而防治松…     

Effects of Gliricidia sepium (Jacq.) Steud and Leucaena leucocephala (Lam.) de Wit on growth and development of Imperata cylindrica (L.) Raeuschel.

Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30 cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing speargrass.     

内蒙古沙区森林碳储量及其动态变化

根据内蒙古第五次和第六次森林资源连续清查资料,分析计算了内蒙古各沙区森林碳储量及其动态变化。结果表明:内蒙古各沙区森林总碳储量为4 898.05万t,其中沙地为4 614.85万t,沙漠为283.2万t。5年间(2003—2008年)内蒙古各沙区森林总碳储量净增加921.07万t,平均每年净增加184.21万t,核算成二氧化碳总量为675.44万t,占内蒙古年排放量二氧化碳的2.36%。