施肥对紫薇生长开花特性的影响研究初报

本文研究施肥对5年生紫薇生长和开花特性的影响,结果表明：不同施肥处理对幼龄紫薇地径及冠幅生长影响不显著,对苗高生长有显著影响,施肥后,紫薇营养生长综合指标OD值的从大到小的次序为PK＞NPK＞NP＞CK＞NK;不同施肥处理间紫薇花序宽、花枝比、着花数有显著差异,但施肥对花序长的影响效果不显著,施肥后紫薇开花质量综合指标OD值的从大到小的次序为NP＞NPK＞CK＞NK＞PK.总体来看,施肥对紫薇开花特性的影响大干营养生长,P是影响该地幼龄紫薇营养生长及开花质量最主要因素,NP和NPK处理对幼龄紫薇生长及开花具有明显促进作用.     

影响塞罕坝机械林场林业有害生物发生的气候因子及测报

随着气候变化和森林经营周期的影响,塞罕坝林场林业有害生物的发生种类从少到多,发生面积从小到大.该文着重研究气候变化对塞罕坝林场林业有害生物发生的影响和测报方法.     

论精品园林工程中的细节效果控制——以成都青羊绿舟·绿岭B区景观工程为例

文章以成都青羊绿舟.绿岭B区景观工程为例,对园林工程施工过程中影响景观效果的关键环节进行分析研究,包括:施工中如何因势利导,发挥优势,从细节到局部、从局部到整体进行全程把控;预防不利于景观效果塑造的情况发生,以人控、物控、技控等"三控"为基础,对影响园建及绿化细节效果的石材切割、对缝、艺术造型、收口等施工关键技术进行研究。     

应用解释结构模型分析松林系统对松材线虫干扰的响应

选用解释结构模型(ISM)分析松林生态系统对松材线虫干扰如何作出响应.结果表明:影响松林生态系统对松材线虫干扰做出响应的系统是一个5级的多级递阶系统,响应结果表现为抵御性和恢复性.群落中优势树种分布格局和松树的生物生态学特性是影响松林生态系统的抵御性的最大因素,受害木伐除和其他措施也通过影响松墨天牛的危害程度和物种分布格局而间接影响到抵御性.对于恢复性而言,除受土壤因子、水文、周围种源和次优或共优树种的生物学特性等直接影响外,气象因子也会直接或间接影响恢复性.海拔、坡度、坡向等地形因子和地理位置的差异和防治水平的提高也影响了松林生态系统对松材线虫干扰作出响应.     

服务修复模型的构建

此模型以顾客满意、员工满意和服务公平的综合理论为基础,应用了行为科学中的资源交换理论、期望理论和社会公平理论.与以前的研究不同,本模型研究了服务失败与服务修复对于顾客评价具体方面的影响,研究了员工的工作满意度对服务失败与服务修复的影响,进而影响到顾客的感知与评价.     

小片水杉丰产林的经济效果

1972年,我们引种了水杉3,000株,经两年的培育,苗木生长良好,到1974年我们利用本站土地营造丰产林7.2亩.到1977年平均生长量超过1.5米,1978年开始郁闭.先后于1979、1981、1983年进行了三次间伐.从造林至今一直生长良好.这小片水杉丰产林的培育,对提高林木单产,美化环境起了典型示范的作用,在解决本地人民对木材之需产生了很大影响.现将小片水杉丰产林经济效果报道如下:     

微坑型微织构硬质合金表面对木材摩擦特性的影响

【目的】探讨木材含水率、木材切面和纤维方向以及运动速度等因素对木材表面摩擦系数的影响规律,为设计更加合理的木材切削刀具表面织构形式提供参考和指导。【方法】以水曲柳和樟子松为研究对象,在具有不同微坑直径硬质合金表面条件下,研究木材含水率、木材切面和纤维方向以及运动速度等因素对木材表面摩擦系数的影响。【结果】与无微坑表面相比,当微坑直径为60μm、含水率为67%±3%时,在水曲柳表面产生的摩擦系数由0. 151降低到0. 091,降幅为39. 7%,在樟子松表面产生的摩擦系数由0. 241降低到0. 164,降幅为32. 0%。木材径切面上纤维方向差异对表面摩擦系数的影响不大,但在横切面上,微坑直径越小,其表现出的摩擦系数越高。摩擦过程中运动速度对表面摩擦系数的影响与木材中的水分有较大关系,当含水率处于生材状态时,表面摩擦系数随运动速度增大而降低,且微坑型结构表面产生的摩擦系数降幅明显高于无微坑表面,无微坑表面产生的摩擦系数由0. 160降低到0. 134,降幅为16. 3%,微坑直径为60μm时的摩擦系数由0. 124降低到0. 071,降幅为42. 7%。【结论】木材含水率状态对微坑型表面微织构与木材之间的摩擦系数影响较大,木材中自由水的存在有利于降低硬质合金与木材表面之间的摩擦系数。微织构直径越小,其接触角平均变化率越大,表面铺展速度越大,越有利于改善木材/硬质合金摩擦副的状态,使表面间的摩擦系数减小。     

风——森林火灾的“怪魔”

风,在影响森林火灾诸多可变因素中为最重要的因素.风的变化可改变火场火的强度,火蔓延的速度,火场面积的大小,火场发展的方向.火场火的变化,地形的变化,天气的变化.又会影响到风.因此掌握风的形成和规律,风对火灾的影响,就可以对风进行预测,就能有效地控制森林火灾的发展.一、火场上的风空气经常处于运动状态,空气在水     

气候变化与森林生态系统:影响、脆弱性与适应性

综述近年来国内外有关气候变化与森林生态系统的相关研究方法与结果,总结已观测到的气候变化对森林物候、森林生产力、森林结构、组成和分布,以及森林碳库的影响,以及未来气候变化可能产生的影响;并对气候变化条件下森林生态系统的脆弱性和适应性评估方法进行总结评述.对目前相关研究的不确定性及存在的问题进行分析,强调未来需要加强的研究领域.     

成都管道工程项目影响因素识别及施工安全管理研究

近年来极端天气的频发,对室外市政管道工程项目造成较大影响,直接影响到工程项目的质量安全和作业人员的生命安全.因此,对当地的极端天气做好科学分析,对工程项目施工安全管理做好细化的针对性工作显得尤为重要.通过数据分析成都市近年来雨期、雨量,发现呈增加趋势,大暴雨出现频次变多,该风险因素将对管道工程项目施工造成不利影响,需要...     

Shrinkage and collapse in thin sections and blocks of Tasmanian mountain ash regrowth

Summary Shrinkage and moisture content measurements for thin sections of Eucalyptus regnans have shown that although total volumetric shrinkage was positively correlated with specific gravity, the relationship did not conform to the general equation s = f (Stamm 1935, 1952) in that the straight regression line was significantly different from a line passing through the origin. This contrasted with the relationship between shrinkage from 17% EMC to 0% moisture content and specific gravity which, in principle, complied with the Stamm formula. The discrepancy arose because shrinkage from the green condition to 17% EMC was negatively related to specific gravity owing to the high variability of the measured fibre saturation point and its negative correlation with specific gravity. These observations were affirmed in a comparison of unit shrinkage-specific gravity regressions where relationships were positively significant but the regression constants were not.Shrinkage behaviour in blocks of E. regnans did not comply with the Stamm formula although the average fibre saturation point (41.8%) was not significantly different from that for sections (38.2%). The near similarity derived from a significantly greater unit shrinkage in blocks (0.49) than that in sections (0.30). It was suggested that the much greater external shrinkage in blocks contained a significant increment of cell collapse induced by drying stress below the fibre saturation point.The authors wish to thank Dr. Allan Miller for statistical assistance and Dr. Aleck Hunter for mathematical assessment     

Shrinkage and collapse in thin sections and blocks of Tasmanian mountain ash regrowth

Summary Total collapse values from the green condition to various equilibrium moisture contents (EMC) were obtained by comparing shrinkage before reconditioning in matched blocks and sections of the wood of Eucalyptus regnans. It was shown that while collapse to 17% EMC comprised the largest portion of total collapse, a significant component, apparently caused by drying stress, developed below 17% EMC. Between 5% EMC and 0% moisture content a collapse recovery of some 1% occurred, seemingly because of changes in drying temperature. After reconditioning, collapse recovery was only partial and a high level of residual collapse remained. It was shown that collapse recovery was highest near the sapwood-heartwood boundary, while residual collapse was highest near the heartwood centre. While residual collapse was weakly negatively correlated with specific gravity, this relationship was not significant after adjustment was made for change in shrinkage after reconditioning in sections. All types of collapse were positively correlated with R-ratios calculated for blocks. However, relationships were not as well defined when R-ratios for sections were employed, the exception being for collapse below 17% EMC which was highly negatively correlated with R. The difference between shrinkage before reconditioning and shrinkage after reconditioning in sections, while totalling near zero, was positively correlated with specific gravity. It was demonstrated that this quantity could not constitute collapse in the traditional sense of collapse of the cell lumens. A possible association with moisture content of the material was discussed.     

青岛老城区里院街区空间解析——基于城市设计基础理论的分析

“里院”是青岛老城一种特有的居住形式,文章运用图底理论,行为场所理论这些当代城市设计的基础理论,对里院街区空间和里院街区开敞空间进行了分析。保护里院街区空间也不应仅仅停留在物质形态,重点也是要考虑居民的需求,以尊重他们的行为方式作为前提,在此基础上提高他们的生活品质。     

Preparation and properties of oligoesterified wood blocks based on anhydride and epoxide

Summary Preparation and properties of oligoesterified woods in the form of block are reviewed. The oligoesterified wood blocks are prepared by stepwise addition reactions of dicarboxylic acid anhydride and epichlorohydrin (EpCl), or one-step chemical treatment with reactant solution of the anhydride and EpCl. Among the preparation methods investigated, the heating-suction method is industrially advantageous. In this method, wood blocks impregnated with the reactant solution are heated and then subjected to suction under reduced pressure and heating, to remove unreacted reactant solution. The oligoesterified wood blocks thus obtained contain oligoester chains formed by the alternate additions of the anhydride and EpCl to OH groups of wood. They also contain small amounts of free oligomers not linked with the wood matrix. Their dimensional stabilities against moisture and water become greater with increase in the apparent total weight increase due to the oligoester chains and the free oligomers. The oligoesterified wood blocks based on phthalic anhydride-EpCl are industrially promising, and exhibit higher compressive and flexural strenghts, greater chemical resistance, electric insulation, and much lower water absorption than untreated wood block. Furthermore, excellent resistances are observed against weathering and biodeterioration.     

Shrinkage and collapse in thin sections and blocks of Tasmanian mountain ash regrowth

Summary The relationship between the R-ratio (the change in external volume per change in associated volume of water) and specific gravity in the wood of E. regnans was shown to be negatively significant for blocks but not significant for sections. The difference arose because of disproportionately high shrinkage in blocks, especially at low specific gravity, and only relatively small differences in fibre saturation point between the two groups.Estimates of progressive lumen change, based on green volume, were calculated using R. It was shown that, for sections, lumen volume increased from green to 5% EMC and then decreased to 0% moisture content; conversely, in blocks, lumen volume decreased to 5% EMC and then increased substantially to 0%. It was suggested that, in blocks, a recovery in the final stages of drying may have caused the reversal in lumen shrinkage. Correspondingly, it was suggested that such changes may be related to the general, non-linear behaviour of external shrinkage near 0% moisture content.Because reconditioned wood may generally contain residual collapse, or may be otherwise modified by the reconditioning process, it was suggested that care should be exercised in the interpretation of results so derived.The authors wish to thank Dr. Aleck Hunter for mathematical assistance     

Chemical kinetics of stress relaxation of compressed wood blocks

Summary Methods of chemical kinetics are used to study stress relaxation behaviour of wood blocks made fromPinus sylvestris and compressed parallel to grain at 20°C and 65% relative humidity. The effect of stress levels on stress behaviour is investigated. It is found that both activation volume and activation energy decrease with increasing stress level. The results prove the validity of the chemical kinetics approach in describing stress relaxation of wood blocks in compression. Suggestive explanations are given for the variations in activation energy and activation volume with stress level.Part of this work was carried out at the School of Agriculture and Forestry Sciences, University of North Wales, Bangor, UK through an ODA TCT fellowship granted to one of the authors (SPSR). He would like to thank Director General, ICFRE (India) and Director, IWST, Bangalore (India) for providing him with the opportunity to work in UK. He would also like to acknowledge the help received from Mrs. Helen Simpson and Dr. Robert Brooke of School of Agriculture and Forestry Sciences, University of North Wales, Bangor, U.K     

Dependence of runout distance on the number of rock blocks in large-scale rock-mass failure experiments

To examine how the number of rock blocks affects the rock-mass runout distance, large-scale outdoor rockfall experiments were physically performed using cubiform granite rock blocks on a slope prepared with granite slabs under both dry and water-saturated conditions. To learn more about the runout mechanism, numerical simulations were also conducted using three-dimensional DEM to reproduce the physical experiments under dry conditions. Longitudinal rock-mass runout distance between the gravity centre in the initial rock block assembly before failure and the apparent gravity centre at final deposition was 10 % larger for experiments under water-saturated conditions than those under dry conditions, with identical numbers of rock blocks in the physical experiments. The physical and numerical experiments revealed that rock blocks at the front and top surfaces had a longer runout distance than those at the rear and bottom surfaces. A rock block scarcely surpassed the rock blocks in front longitudinally and the rock blocks next to it laterally. The equivalent coefficient of friction between gravity centres was positively correlated with the number of rock blocks, which contradicts the findings of a negative correlation between the volume of sturzstroms (rockfall avalanches) and the equivalent coefficient of friction in classic studies on the long runout mechanisms. Our results were likely attributable to the fact that more kinetic energy was dissipated due to repeated inelastic intercollisions with other surrounding rock blocks and granite slabs when the initial rock-mass volume (number of rock blocks) was larger.     

Interaction between Epicoccum purpurascens and xylophagous basidiomycetes on wood blocks

Epicoccum purpurascens, a component of the bark micromycota, was evaluated as a potential biocontrol agent for three decay‐causing hymenomycetes frequently found in Buenos Aires city trees, Ganoderma platense, Inonotus rickii and Rigidoporus ulmarius. Treatments consisted of dual cultures of E. purpurascens and xylophagous fungi on box elder (Acer negundo) wood blocks. Two inoculation sequences were tested: (i) the biocontrol agent as the first microorganism inoculated followed by the pathogen; and (ii) the xylophagous fungus as the first microorganism inoculated followed by the biocontrol agent. After 3 months of incubation, percentage dry weight loss was calculated. When E. purpurascens was allowed to colonize wood blocks before the introduction of the xylophagous fungus, dry weight loss was significantly reduced in all instances. However, as a secondary colonizer, E. purpurascens mildly reduced the weight loss caused by G. platense, had no effect on degradation by I. rickii and increased wood weight loss by R. ulmarius.     

Relating shape to human aesthetic evaluations of harvest blocks from an aerial perspective

Forest planners employ various techniques to mitigate the visible effects of harvesting, including by manipulating the shape of harvest blocks. Shape is a common indicator of preference in aesthetic evaluations of landscape and harvest block design. However, the majority of perception-based research in the field of landscape aesthetics has focused on the perspective view. This study investigates the perceptual effects of two shape characteristics: complexity and image mode, as viewed from the air. Order and subjects’ area of study were also tested. Forty-five aerial images of harvest blocks and 45 digitally-manipulated harvest block shapes were used as the harvest and shape image sets, respectively. Seventy-five subjects rated each image for preference. Complexity was the strongest predictor of preference. Preference increased as complexity level increased, regardless of the image mode in which the shapes were presented. Subjects with an environmental focus in their area of study demonstrated a more prominent complexity effect than those from non-environmental fields. Both image mode and area of study had small but significant effects on preference ratings. These results confirm previous findings pertaining to complexity in psychology and landscape aesthetics, in which complexity, as a characteristic of shape, plays a role in predicting preference.