杨树人工林林木蓄积量调查方法对比研究

采用全林每木检尺法、标准地调查法、样圆调查法、角规调查法对同一块杨树人工林林木蓄积量进行调查,比较了不同调查方法的调查精度与工作量大小.结果表明：四种调查方法调查所得林木蓄积量无明显差异.以全林每木检尺法调查的林木蓄积量为标准值,标准地调查法所测数据精度最高,其次为样圆调查法、角规调查法.从调查工作量上来看,全林每木检尺法工作量最大,样圆调查法与角规调查法操作容易,工作效率较高.     

森林资源二类调查方法概论

综述森林资源二类调查及其调查的两种方法:抽样调查和小班调查.并对林木蓄积量和生长量调查的计算技术进行了研讨.     

土地利用基础图件与数据更新探析

介绍了项目实施的原则,包括统一部署、充分利用原有资料、实用与创新等.从准备阶段、内业预处理、外业调查阶段、乡村两级行政境界调查、权属调查、图斑地块调查、线状地物调查、零星地物调查等方面详细地探讨了组织及实施的各项工作,并对土地利用更新调查工作进行总结.     

七星峰国家级森林公园木本植物资源调查及其景观特色研究

采用样线调查和样方调查的方法,对七星峰国家级森林公园内的木本植物资源进行了调查.通过调查,发现七星峰国家森林公园内木本植物资源种类丰富,共有木本植物种类24科40属59种.并对具有开发利用价值的景观特色进行了简要介绍.     

全国森林资源清查和规划设计调查结果的比较及其使用

介绍了历次一类调查结果和江西省同期一、二类调查主要指标.提出当二类调查全部用抽样控制时,用估计区间作比较,而二类调查部分和全部未作抽样控制时,以允许误差为标准作比较;一类调查资料用于制定本地区的林业计划、规划以及对外数据公布等,二类调查资料用于分解计划、规划到二类调查单位等.     

第二次全国土地大调查若干问题的思考

第二次全国土地调查已经进入尾声了,结合在第二次土地大调查中的相关经历,对开展第二次全国土地调查的意义和重要性进行了再思考,并对开展土地调查工作若干方面的问题进行了分析和总结.要做好土地调查工作,应该重点从政府部门组织管理、宣传工作、调查队伍质量、充足经费、土地调查技术路线设计等方面去解决.     

关于林下资源及其调查方法的几点思考

叙述了林下资源的概念.论述了林下资源与资源植物、经济植物、非木质资源的关系.提出了林下资源的调查方法、调查方案.     

林业调查规划档案管理工作亟待加强

林业调查规划工作是现代林业建设的重要一环,加强林业调查规划档案管理工作有利于现代林业的发展.笔者分析了林业调查规划档案管理对现代林业建设的意义,介绍了林业调查规划档案管理工作的种类,提出加强其管理的基本路径,以为生态文明建设的发展提供参考.     

建水县森林资源二类调查的主要问题及对策

分析了建水县森林资源二类调查中调查设备、技术手段、调查人员、调查方法、调查成果中存在的问题,并针对各方面的不足提出了相应的对策,为建水县森林资源的数字化建设提供参考依据.     

全区林业收入调查统计总结表彰会议召开

1997年2月17日至19日,全区林业收入调查统计总结表彰会议在呼和浩特召开.林业收入调查统计指标,是反映林业生产建设成果的重要指标.进行林业收入调查统计工作,对林业生产建设的宏观调控,制定林业发展规划,调整林业产业结构以及提高林业在国民经济中的地位具有重大意义.为此,自治区林业厅于1994年制定了林业收入调查统计方案及其指标体系,并在当年底开始进行了林业收入调查统计工作.各盟市林业主管部门高度重视并加强了对这项工作的领导,大多数盟市成立了林业收入调查统计领导小组,并将林业收入调查统计办公室设在计财科,强化了林业收入调查统计工作.各盟市每年以会     

A comparison between three different methods of measuring knot parameters in picea abies

Both foresters and sawmillers are interested in the knot structure of trees; in particular, position and number of knots, knot diameter, knot length and dead knot border. For research purposes, it is possible today to carry out non‐destructive measurements using computer tomography (CT) and image analysis. The aim of this study was to measure knot parameters on Norway spruce (Picea abies (L.) Karst.) using a non‐destructive method developed for Scots pine (Pinus sylvestris L.), and to compare the results of this method with the results of two different destructive methods. In order to do this, two Norway spruce stems were scanned by CT. Then five logs from one stem were cut into flitches 20 mm thick and the defects on the sawn surfaces were scanned manually. The other stem was cut just above every whorl and then each knot was split through its centre and the knot parameters were measured manually. The study showed that the CT method compares well with the destructive methods. It is a reasonably fast, non‐destructive method which measures position and diameter of knots and detects larger knots with acceptable accuracy. The study also showed that a large number of smaller knots were not found by the CT method and that the CT method measured knot length and dead knot border with low accuracy. This means that the CT method has to be adjusted to Norway spruce in order to improve its ability to measure knot length and dead knot border and to detect smaller knots.     

园林设计中生态原则应用初探

园林设计中生态原则应用是为了在利用自然的过程中,对环境的破坏影响达到最小而产出达到最大。本文从设计过程中生态原则的角度进行了重点分析。     

两个热带树种（柚木和印度实竹）叶面积指数估测异速生长方程

通过破坏性抽样、相片网格法和落叶采受器法,获得了印度Shoolpaneshwar野生动物禁猎区内生长的柚木和印度实竹叶面积指数。建立了一个异速生长方程来决定两个树种的叶面积指数。结果表明,异速生长方程获得的叶面积指数与破坏性抽样、相片网格法和落叶采受器法评估得到的指数值相近;2种测定方式下,柚木的均方根误差分别是0.90和1.15,印度实竹的均方根误差分别为0.38和0.46。估计的和计算获得的叶面积指数值匹配性较好,说明用建立的方程计算得到的2个树种叶面积指数的准确性较好。总之,冠幅伸展是一个估计树木叶面积较好的且敏感的参数。本文所提出的方程可以用作估计热带柚木和印度实竹叶面积指数。图4表1参22。     

枣缩果病研究进展

本文综述了 2 0世纪 70年代以来我国枣缩果病病原及其发病规律、传播途径和防治技术等方面所取得的主要科研成果 ,并提出了枣缩果病研究上存在的主要问题和今后的主攻方向     

山·水·林——“98洪灾”后的反思

从“９８洪灾”中看出５０ａ来,长江的治理在策略上是有失误的。首先是长江治理战略思想上的失误,缺乏治理长江流域整体生态环境的系统思想。其次是具体措施上的失误,见水不见山,重水轻山;见水库不见湖泊,重修水库,轻保湖泊、库容;见堤坝不见河道,重筑堤堵水,轻疏导排障;投资重水利,轻林业。治江策略,首先要具有全流域生态环境治理的整体系统思想。对策略措施是“留”、“蓄”、“导”     

西双版纳自然保护区热带季节雨林破坏后的恢复状况调查

由于热带季节雨林是种植砂仁最适合的场所,因此当地居民大量地将砂仁种植在季节雨林下,对其群落结构及组成造成了严重破坏,导致大量物种的流失。对遭受破坏的群落恢复状况进行调查,结果显示,由于人为活动增加了林下的透光度和生长空间,对幼树和幼苗的生长具有一定的促进作用。只要停止人为破坏活动,经过一定时间,群落仍可得到恢复。     

Storm-induced tree resistance and chemical differences in Norway spruce (Picea abies)

Introduction   

Windstorm is one of the most destructive environmental disturbance factors on forests, but its influence on conifer defense chemistry and susceptibility to insects and diseases is not well understood.     

内蒙古阿拉善左旗沙蒿尖翅吉丁生物学特性初步研究

沙蒿尖翅吉丁为沙蒿的一种毁灭性蛀干害虫,寄主为白沙蒿,在阿拉善左旗一年一代,以幼虫在浅层木质部蛀建蛀道越冬,第2年4月开始化蛹.5月底到7月底为成虫期和卵期,为防治适期.     

Measurement of spiral grain with computed tomography

Spiral grain is a feature of wood that affects the shape of the sawn timber. Boards sawn from logs with a large spiral grain have a tendency to twist when the moisture content changes. In sawmills the spiral grain in logs is judged manually. For research purposes the spiral grain in stems and logs is normally measured by destructive methods. In this study the spiral grain of the stems was measured nondestructively with a computed tomography (CT) scanner. Twelve Norway spruce (Picea abies) stems from two stands in Sweden were scanned with a CT scanner with one cross-sectional scan every 10mm along the stem. Concentric surfaces at various distances from the pith were reconstructed from the stack of CT images. In these concentric-surface images, which show various internal features of the log. the spiral grain angle was measured at different distances from the pith and at different heights in the stem. The destructive measurements of the spiral grain were carried out on disks from the top ends of the logs. On these disks the spiral grain was measured at different distances from the pith with a protractor. Finally, the results from the destructive method were compared with the results from analysis of the CT images. The nondestructive and destructive measurements were compared in pairs with the same radial and approximately the same height position in each pair. The correlations (r) between the two methods were 0.81 and 0.71. respectively, for the two stands. It was concluded that it is possible to measure the spiral grain angle nondestructively with a CT scanner.An outline of this study was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto     

多层砖房抗震能力的探讨

通过对近几年来我国发生的几次大地震进行了分析。提出增强多层砖房抗震能力的措施几点建议。