北京地区乔木郁闭度测量研究

比较了国内外已有的乔木郁闭度测量方法的优缺点,在样点法特别是观测管法的基础上,以北京延庆地区乔木林为对象,对郁闭度的激光测量进行了研究。实验改进了观察管法,对在野外测量乔木林郁闭度时精确测量所需样点数进行了研究,可以为野外快速、简洁、精确地测量乔木林郁闭度提供新的方法与参考。     

公路绿化主要树种滞尘潜力模拟试验研究

利用绿化植物滞尘已成为缓解大气颗粒污染的最有效途径,选择具有代表性的常见公路绿化树种,通过对其叶片滞尘潜力的探讨研究,以期筛选出滞尘能力强的植物,为公路交通环境的改善提供理论依据。结果表明,不同植物的滞尘潜力差异显著,阔叶乔木中二球悬铃木、杨树、国槐叶片的滞尘潜力最大,分别为6.495 9 g/m2,5.736 8 g/m2,4.791 9 g/m2;常绿乔木中,侧柏是较好的滞尘树种,最大滞尘量为7.568 8 g/m2;灌木植物以忍冬叶片的滞尘能力最强,其次为紫丁香及卫矛,最大滞尘量分别为7.084 7 g/m2,6.062 5 g/m2,5.878 9 g/m2.     

RTK技术解析及在工程测量中的应用

GPS（RTK）改变了传统的测量方式,使原本复杂、费时、费力的工作变得简单,它的出现是测绘行业发展的重大里程碑,对测绘行业的发展起到巨大的推动作用。     

黑木相思株内木材基本材性变化与树龄关系的研究

对不同树龄和径向位置黑木相思木材的物理和主要力学性质测定研究表明:黑木相思株内边材、心材密度和主要力学性质随着树龄的增大而增大,径向和弦向的体积干缩率随着树龄的增大而减小;相同树龄黑木相思的边材密度和力学性能比心材小,干缩率比心材大.因此,在利用黑木相思时应对树龄、心边材径向位置加以特别考虑.     

子京和油丹的研究与保护

子京和油丹是我国海南省珍贵用材树种,有着重要的经济和科研价值,但天然林资源逐渐减少,均被列为国家二级濒危重点保护野生植物,急需加强对子京和油丹的保护、研究和开发利用.在进行子京和油丹天然资源调查和收集的基础上,文章从应用价值、生物学特性、分布生境、濒危现状、繁殖育苗、引种栽培和保护利用等方面进行了介绍和探讨,提出了子京...     

基于小波包原理的蚕茧无损检测研究

提出了基于声学的蚕茧无损检测新方法，研究了利用小波包原理提取噪声信号的特征值的方法。噪声信号经过小波包分解后，得到各频段内的信号，将各频段内信号的能量谱作为识别蚕蛹质量的特征值。结果表明，通过小波包原理提取的能量谱特征值能有效地识别出蚕蛹的质量，解决了蚕茧无损检测过程中难找出与蚕蛹质量有关的信号特征值的难题。     

自动测量胸径和树高便携设备的研制与测量精度分析

胸径和树高测量是评价立地质量和林木生长状况的重要依据,该文以图像自动识别原理、摄影测量原理、相似三角形几何原理和三角函数原理为理论基础,研制了可测量胸径和树高的多功能便携式微型超站仪,该设备集成电荷藕合器件图像传感器、倾角传感器、激光测距传感器、中央处理器、存储器、液晶显示屏,测量时可获取测站点到待测点的倾角和距离2个参数值,并记录存储测量时的图像信息,通过仪器的嵌入式操作程序,实现胸径的自动测量、树高测量、任意处直径自动测量、基本测量等4项基本功能。通过试验验证,215株立木的单次胸径测量的平均绝对误差为0.369 cm,平均相对误差为2.08%。101株立木的单次树高测量的平均相对误差为1.44%。胸径测量精度达到97.92%,树高测量精度达到98.56%,符合国家森林资源连续清查中的测量精度要求。该设备为森林资源调查提供了参考。     

Soil nutrient supply and biomass production in a mixed forest on a skeleton‐rich soil and an adjacent beech forest

In the natural forest communities of Central Europe, beech (Fagus sylvatica L.) predominates in the tree layer over a wide range of soil conditions. An exception with respect to the dominance of beech are skeleton‐rich soils such as screes where up to 10 broad‐leaved trees co‐exist. In such a Tilia‐Fagus‐Fraxinus‐Acer‐Ulmus forest and an adjacent mono‐specific beech forest we compared (1) soil nutrient pools and net nitrogen mineralization rates, (2) leaf nutrient levels, and (3) leaf litter production and stem increment rates in order to evaluate the relationship between soil conditions and tree species composition. In the mixed forest only a small quantity of fine earth was present (35 g l^—1) which was distributed in patches between basalt stones; whereas a significantly higher (P < 0.05) soil quantity (182 g l^—1) was found in the beech forest. In the soil patches of the mixed forest C and N concentrations and also concentrations of exchangeable nutrients (K, Ca, Mg) were significantly higher than in the beech forest. Net N mineralization rates on soil dry weight basis in the mixed forest exceeded those in the beech forest by a factor of 2.6. Due to differences in fine earth and stone contents, the volume related soil K pool and the N mineralization rate were lower in the mixed forest (52 kg N ha^—1 yr^—1, 0—10 cm depth) than in the beech forest (105 kg N ha^—1 yr^—1). The leaf N and K concentrations of the beech trees did not differ significantly between the stands, which suggests that plant nutrition was not impaired. In the mixed forest leaf litter fall (11 %) and the increment rate of stem basal area (52 %) were lower than in the beech forest. Thus, compared with the adjacent beech forest, the mixed forest stand was characterized by a low volume of patchy distributed nutrient‐rich soil, a lower volume related K pool and N mineralization rate, and low rates of stem increment. Together with other factors such as water availability these patterns may contribute to an explanation of the diverse tree species composition on Central European screes.     

~(134)Cs在茶树上的行为

茶树喷洒~(134)Cs后,~(134)Cs在老茶叶上的残留和新茶叶上的吸收都遵循一级反应动力学模式。~(134)Cs叶面污染后危害性最大,水质污染和土壤污染具有潜在的危害性。茶树对~(134)Cs的富集能力低,K值为0.02;鲜茶叶经制茶加工后,~(134)Cs的损失率达13.3％;茶叶经4次浸泡后,~(134)Cs的总浸出率为83.6％。     

根据形态学和分子系统学特征界定拟盘多毛孢属的种

以拟盘多毛孢属108个ITS（内转录间区）序列建立了分子系统树,探讨拟盘多毛孢属的形态特征与分子系统树的相互关系.结果表明,拟盘多毛孢属首先按照分生孢子有色胞的颜色区分为暗色和淡色（同色）2个分支,暗色组再分成2个亚分支--同色亚分支和异色亚分支,淡色分支内进一步根据顶端附属丝特征和基部附属丝的有无区分为7个亚分支.寄主植物的某个分类单元在拟盘多毛孢属的分子系统树上并未形成特定的分支.通过对形态特征与分子系统树结合分析,重新界定小孢拟盘多毛孢（Pestalotiopsis microspora）、异色拟盘多毛孢（P.versicolor）和茶拟盘多毛孢（P.theae）.