树木年轮宽度数字图像测量方法研究

提出了利用平板扫描仪、电脑等常规办公设备测量树木年轮宽度的数字图像测量方法,分别应用数字图像测量法和树木年轮分析仪测量了5个年轮圆盘的宽度,以年轮分析系统为基准,对数字图像法进行了精度检验,并从测量效率、经济成本等方面对两种方法进行了综合对比分析。结果表明:数字图像测量法的精度完全能够满足年轮宽度相关研究的要求,且具有测量方法简单、设备普及率高、经济成本低等优点。     

楸树心材与边材的生长特征及变异规律

为系统了解珍贵阔叶树楸树心材与边材的生长特征及边心材转化规律,采用树木年轮分析仪对5株楸树不同树高处的圆盘进行年轮数、宽度等生长特征测定,建立心材与树木各生长量之间的回归模型。结果表明:楸树年轮宽度在10～15年达到峰值,可持续10年左右;心材起始树龄为5.26a,心材形成速率为0.90轮/a;属于生长收获周期短、心材形成时期较早且形成速率较快的树种。     

微机与树干解析装置连接系统的建立与初步应用

传统进行树干解析时，在判读年轮、量测年轮宽度和计算上容易产生较大的误差或错误。从日本引进的树干解析装置对圆盘年轮的查定和宽度量测具有相当高的精度，利用微机与其连接，可充分发挥两者的优势。但引进的程序在使用上存在一些问题，经笔者修改并在原有基础上重新编程后，对部分解析本进行实测和数据计算，结果表明，该系统具有测定和计算精度高、操作简便、速度快的特点，可以完成从测定到结果输出工作量的95％．     

一种对年轮图像双边滤波增强的树龄测量方法

树木圆盘年轮图像分析是一种具有较强实用价值的树龄测量方法,但树木横截面上的色斑、锯痕、木材组织中的粗大管孔等都会导致年轮图像发生灰度变化,降低树龄检测精度。为此,提出了一种新的树木年轮图像增强的树龄测量方法:首先采用双边滤波对树木年轮图像进行图像增强,在保留年轮边缘信息的同时抑制锯痕、色斑等导致的灰度变化;然后采用改进的Canny算法对年轮图像进行边缘检测,为了克服传统Canny算子对噪声敏感的缺点,在求取年轮图像的梯度时,计算水平、垂直、45°、135°等4个方向的梯度分量;最后根据多数投票原则,统计年轮图像中的边缘数量,实现树龄测量。实验结果表明,提出的方法能够有效抑制色斑、锯痕、粗大管孔等因素的干扰,得到的年轮边缘图像光滑、清晰,统计得到的树龄与真实情况一致。     

板栗年轮结构对北京地区气候因子的响应分析

以北京地区板栗为材料,建立板栗年轮宽度、早材宽度和晚材宽度3项年轮结构指标的标准化年表和差值年表,分析板栗径向生长与气候因子间的相关关系和响应,并对可重建的气候因子进行筛选。结果表明：板栗年轮宽度和晚材宽度的年表质量明显好于早材宽度年表,其中差值年表优于标准化年表,其样本总体代表性达到93%,第1主成分方差解释量达到40%。差值年表与气候因子的相关分析和响应分析结果表明：年轮宽度、早材宽度和晚材宽度与各项气候因子间响应关系不同,在将来重建过去气候时,可利用年轮宽度和晚材宽度重建当年6月的温度,晚材宽度还可以重建当年7月的降水,早材宽度重建当年3月和4月的温度。     

侧柏年轮宽度和年轮密度对气候变化的响应

通过响应函数分析和多元回归分析等年轮气候学方法,研究北京地区侧柏年轮宽度和年轮密度对气候变化的响应.结果表明:侧柏年轮宽度序列和年轮密度序列对气候变化相当敏感.前一年10月到当年9月的月平均气温和月降水量的响应函数模型可解释年轮宽度变化的58.45%,年轮密度变化的77.81%.夏季降水对侧柏年轮宽度有显著的正效应,而对年轮密度则表现出负效应.与降水的影响相反,夏季气温对侧柏年轮宽度表现出显著的负效应,对年轮密度表现出显著的正效应.其中,当年7月的气温和降水对侧柏年轮宽度和年轮密度的作用尤为显著.说明侧柏的年轮宽度和年轮密度均可用于年轮气候学研究,且年轮密度包含的信息量高于年轮宽度.     

温度和降水对树木年轮宽度影响研究进展

文章概括了温度和降水对树木年轮宽度的影响,分析了树木年轮学的研究方法和最新研究进展,探讨了目前树木年轮学研究中的不足。目前树木年轮学研究主要集中于对偏远和高寒地区天然林林缘木或边缘木的研究,对人工林研究甚少。树木年轮研究对取样环境的严格要求,使研究工作受到限制,不能充分反映气候变化对林木年轮生长的影响,应充分考虑林分密度等林分结构对林木径向生长的影响,扩大研究领域。在不同季节气候因子对人工林年轮宽度影响机理方面有必要深入研究。     

几种常用的树木叶面积测量方法比较

以随机采集的6种延安市区绿化植物(白蜡、刺槐、紫丁香、五角枫、银杏和月季)新鲜叶片为材料,分别用激光叶面积仪、AutoCAD和ENVI进行测量。通过统计比较发现,激光叶面积仪测量结果平均偏大,精度最低;AutoCAD与ENVI在测量结果上差异不显著,但在精度上AutoCAD高于ENVI。AutoCAD测量叶片面积的平均耗时为139.6 s,是ENVI方法的3~4倍。通过AutoCAD测量方法测定以上6种树木叶片的长度、宽度和叶面积,并拟合出6种树木的叶面积线性方程,相关系数与决定系数均达到极显著水平。经过验证,这6个叶面积线性方程均是可靠的,可以用于延安市这6种植物叶片面积的测量和叶面积衍生指标的估算。     

人工林马尾松晚材率、年轮宽度和组织比量变异研究

对22年生人工林马尾松木材年轮宽度、晚材率和组织比量进行系统的测量、统计和分析，结果表明，年轮宽度随树龄增加先增加后减小，而随树干高度的增加先减小后增加。晚材率随着树龄增加呈波动增大，而随树干高度的增加呈逐渐减小趋势。木射线比量和树脂道比量随树龄增加呈波动增大，但总体变幅不大，而前者随树干高度的增加呈波动减小，后者先减小再增大。管胞比量随树龄增加呈波动减小，而随树干高度的增加先增加，达到一定值后减小，然后再增加。方差分析表明，年轮宽度、晚材率、组织比量在各年轮间、各高度间差异显著或极显著。     

树木年轮与全球变暖的关系研究进展

树木年轮宽度、密度、同位素含量等都与气候因子温度、湿度以及其他成分的变化有复杂的相关关系。总结了树木年轮的几种研究方法在全球温度变化中的应用, 同时利用树木年轮分析对全球变化研究中存在的问题做了简要的探讨, 并对未来全球变化条件下年轮年代学研究的方向作了展望。     

The Crown Window — a simple device for measuring tree crowns

The paper presents a new method for assessing crown radii at different tree heights, using a simple mechanical device, the crown window. The accuracy of the crown window measuring device is evaluated using measurement data from different objects. The device is easy to manufacture and proved to be more useful than other more sophisticated techniques, such as digital photo analysis or laser based instruments in estimating crown radii and their corresponding heights with acceptable accuracy.     

Derivation of stumpage value and logging costs for individual forest stands using aerial photographs and cartographic modelling

A procedure for calculation of stumpage value and logging costs of individual mature forest stands using aerial photo‐interpretation and a grid‐based geographical information system (GIS) is presented. The stumpage value may be computed from characteristics related to the trees, i.e. site index, stand mean height, crown closure, and tree species distribution, using price equations. By means of cost equations, the logging costs may be calculated from the tree characteristics and the terrain characteristics of slope gradient and skidding distance. The practical application of the procedure was demonstrated by a case study in a 710 ha forest area in southern Norway. The tree characteristics were determined by photo‐interpretation of individual stands. Skid paths for wood transportation from the stands to landings along the forest roads were delineated by photo‐interpretation of the ground conditions. Slope and skidding distances were derived by a digital elevation model and cartographic modelling. Finally, the photo‐interpreted tree characteristics and the computed slope and skidding distances were used for calculation of the stumpage value and the logging costs of each stand. According to previous tests, the accuracy of the procedure corresponded to the accuracy that could be achieved by the field‐survey methods used most frequently.     

New strategies for estimation of cut and fill areas in road design with different ground cross-section offsets

Earthwork operations accounted for great amount of forest road construction costs. Any Optimization in planning road profile needs a reliable objective function that calculates earthwork volume in an appropriate time and accuracy. This study aimed at incorporating the shape of the ground cross sections in calculating cut/fill areas using three alternative methods including: Multiple Linear Regression (MLR), Artificial Neural Network (ANN) and heuristic programming in MATLAB environment. The accuracy of results was validated via AutoCAD as a manual method for area calculation of road’s cross-section. Trapezoidal method applied to calculate the area of cut/fill in the heuristic method. Paired sample T-Test and statistical analysis (ANOVA) with confidence level of 0.95 indicated that the heuristic method not only reduced computing time but also provided accurate estimations as same as the manual AutoCAD based method. It can be concluded that although MLR and ANN estimations were as well as AutoCAD results within a reasonable time, they need to be retrained by adding, removing or changing entrance parameters.     

基准地价评估图件编绘中的AutoCAD技术

从基准地价评估图件编绘的基本要求出发，以《城镇土地估价规程》规定为依据，结合基准地价评估的工作实践，介绍了采用AutCAD技术绘制基准地价评估工作底图、地价样点图和基准地价图的方法和过程，并分析了AutCAD技术在基准地价评估图件编绘中的突出优点。     

Forest edge quantification by line intersect sampling in aerial photographs

There is a need for accurate and efficient methods for quantification and characterisation of forest edges at the landscape level in order to understand and mitigate the effects of forest fragmentation on biodiversity. We present and evaluate a method for collecting detailed data on forest edges in aerial photographs by using line intersect sampling (LIS). A digital photogrammetric system was used to collect data from scanned colour infrared photographs in a managed boreal forest landscape. We focused on high-contrast edges between forest (height ≥ 10 m) and adjoining open habitat or young, regenerating forest (height ≤ 5 m). We evaluated the air photo interpretation with respect to accuracy in estimated edge length, edge detection, edge type classification and structural variables recorded in 20 m radius plots, using detailed field data as reference. The estimated length of forest edge in the air photo interpretation (52 ± 8.8 m ha⁻¹; mean ± standard error) was close to that in the field survey (58 ± 9.3 m ha⁻¹). The accuracy in edge type classification (type of open habitat) was high (88% correctly classified). Both tree height and canopy cover showed strong relationships with the field data in the forest, but tree height was underestimated by 2.3 m. Data collection was eight times faster and five times more cost-effective in aerial photographs than in field sampling. The study shows that line intersect sampling in aerial photographs has large potential application as a general tool for collecting detailed information on the quantity and characteristics of high-contrast edges in managed forest ecosystems.     

Bamboo nanofiber preparation by HCW and grinding treatment and its application for nanocomposite

A new approach to prepare cellulose nanofiber was attempted using the combined method of hot-compressed water (HCW) treatment and disk milling. The HCW treatment was effective in loosening the cell wall structure and enhancing fibrillation by disk milling. The fibrillated products showed fine fibrous morphology at the nanometer scale. Filtration time and specific surface area were measured as criteria of the degree of fibrillation, and both these values were increased in nanofibers obtained by disk milling after HCW treatment. The obtained nanofiber-reinforced polyurethane composite was prepared, and its tensile properties were drastically improved by the increased nanofiber content.     

万寿菊根氯仿提取物对枣尺蠖的光化学活性研究

万寿菊(Tagetes erecta)为菊科万寿菊属植物,广泛分布于世界各地.除作为一般观赏花卉外,由于其根内含有特殊的活性物质而备受重视,成为从2 400种已记载的控害植物中挑选出来的43种广谱控害植物之一,被誉为"控害植物精华"(王新国等,2002).     

基于VB的AutoCAD二次开发与图形自动生成技术

通过例程分析对AutoCAD二次开发实现自动成图的几种不同方法的基本原理和特点。重点介绍了利用VB的ActiVex技术进行AutoCAD图形自动生成的原理、方法与特点，提出了自动成图的程序设计思路和流程。     

在森林二类调查中用TM影象代替航片的研究实例

简述了在内蒙古两个林业局的森林二类调查中用ＴＭ影象代替航片进行区划、调绘、定位和面积量算、测树因子估测的试验方法和结果。试验与生产同步展开，进行了对照，数据表明，用１∶５万ＴＭ影象代替航片进行区划、调绘、求积，其精度均能满足规程要求，但在测树因子估测方面尚不理想