固定样地调查应注意的问题

森林资源连续清查是以掌握宏观森林资源现状与建立生态综合监测体系为目的，利用固定样地为主进行定期复查森林资源的调查方法。固定样地中各因子的调查，包括森林、林木、林地的数量、质量、结构与分布及动态变化，森林健康状况与生态功能，森林生态系统多样性，土地沙化、石漠化、湿地类型的面积、分布及其动态变化，     

关于森林资源连续清查中几个问题的思考

确定样地数量时要综合考虑样地面积、样地内的工作，以提高效率。计算机原来的程序应扩大功能、提高运算准确性和改进使用方法。发掘清查成果潜力，进行跨行业合作。     

森林抽样调查中的实测样地

总结过往森林资源调查的经验,就森林抽样调查中实测样地的种类、形状、面积量测和调查方法提出了见解,并对不同样地形状和面积大小做了分析比较。     

RTD GPS用于森林资源固定样地调查的研究

讨论了应用RTDGPS从事森林资源调查的一般原理、方法和步骤。侧重探讨了RTDGPS用于固定样地中心恢复的方法及新样地建立的过程 ,样木检尺的观测和自动记录 ;讨论了RTDGPS中存在的问题、进一步完善的途径及其发展前景。通过实例验证了RTDGPS ;用于森林资源固定样地调查的可行性。     

森林清查中的样地类型

森林清查中的样地类型宋劲松（林业部调查规划院北京１００７１４）由于抽样技术不断地引入森林清查中，各种不同类型、不同大小、形状的样地应需而出。为准确、高效、高精度地进行森林抽样调查发挥着举足轻重的作用。当前，我国已经正式地提出了建立地方森林资源监测体系...     

野生花卉资源样地调查法研究简报

报道了一种新的野生花卉资源样地调查样方法，即利用县级森林资源调查固定样地的调查成果，在固定样地中抽取并测设里生花卉资源查样地，该方法科学性较高，能达到调查成本低，效率高，精度有保证的目的，对野生经济植物资源调查具有推广价值和指导意义，文中对野生卉资源样地调查方法和蕴藏量估算作了简要介绍。     

森林资源监测地面固定样地优化研究

地面固定样地是大区域尺度范围内开展森林资源监测的基本抽样调查单元。地面固定样地对林分的预估精度将直接影响到整体区域监测结果的准确性。从样地类型、空间排列方式、样地尺度大小出发,在1 hm²大样地中采用随机抽样法,通过抽样精度验证在不同类型林分中开展森林资源监测的最优样地类型。结果表明：1)在不同类型林分中开展蓄积量监测的最优样地面积尺度大小不一,在布设地面固定样地时,应当根据林分起源、龄组的不同,确定样地面积、间距;2)在样地面积相同情况下,单一圆形样地抽样监测精度略高于单一方形样地,群团样地的蓄积抽样监测精度明显高于单一样地,四点圆形群团样地抽样监测精度略高于方阵式群团样地。     

方形样地与多边形样地的森林资源调查的精度分析

本文对几种标准地和样地的森林资源调查方法进行精度分析,找出产生误差原因,以及在不同林相条件下的精度变化。使林业企业在今后的森林调查设计中,根据各种林相条件,选择不同的森林调查方法,达到提高调查精度,减少森林调查误差的目的。     

利用PDA对控制样地调查的方法

主要介绍了掌上森林资源调查仪在控制样地调查中的应用方法,其中包括控制样地点位置查询和导航、控制样地登陆、调查数据属性输入及控制样地主要信息查询等方面内容。     

毛竹林试验地设置和调查方法的研究

通过对浙江、江西、湖南等省的丰产林(Ⅰ)、中产林(Ⅱ)、低产林(Ⅲ)三种类型毛竹林的大量调查,计算得出如下结果:①在同一毛竹林类型中竹林胸径的变异度最小,蓄积量次之,新竹产量变异度最大。②同一调查因子中毛竹林类型不同变异度不同,Ⅰ类竹林的变异度最小,Ⅲ类竹林变异度最大。同一调查因子和同一毛竹林类型中变异度也各不相同。因此毛竹林调查面积应根据不同的竹林类型和不同的调查目的来确定。如进行资源或蓄积量调查,适宜的竹林面积Ⅰ类竹林应是400m~2,Ⅱ、Ⅲ类竹林应为500—600m~2。③毛竹林虽有很强的边际效应,但计算表明,毛竹林样地的形状不一定拘于正方形,可因地制宜设置长方形或正方形。④通过对毛竹林蓄积量或产量的几种常用计算方法的误差率对比,提出用平方平均胸径来求算蓄积量或产量是较简便又可靠的方法。同时对毛竹林蓄积量或产量计算中胸径与眉径的换算规律进行了探讨。     

Poisson sampling and some alternatives in timber sales sampling

Sampling schemes are studied for timber sales where every tree in the population has to be visited. A strong linear relationship is known to hold between the variable of interest, volume in m³ (y), and tree basal area times height (x) (in cm²m). Purposive sampling of trees over the X-range and stratified sampling with regression estimators are recommended as worthwhile alternatives to Poisson sampling for efficiency and for yielding consistently good results where the model between the dependent and independent variables is known to be reasonable. Two other designs, selecting the n trees with largest X-values and the trees with 20% smallest and 80% largest X-values, are shown to be high-risk procedures.     

Combining double sampling for stratification and cluster sampling to a three-level sampling design for continuous forest inventories

We extend the well-known double sampling for stratification sampling scheme by cluster subsampling to a three-level design and present corresponding estimators based on the infinite population approach in the first phase. After stratification of the sample points (phase I), a second-phase sample is drawn independently among the first-phase points within each stratum. On level III, clusters are formed of those phase II points and a sample of clusters is finally drawn without replacement. We used the forest planning units compartment and subdistrict as clusters and moreover formed clusters with a heuristic for the vehicle routing problem. The precision of the new estimator was compared to that achieved with classical double sampling for stratification in a case study. The results indicate that the expected increase in sampling errors caused by clustering cannot be compensated by the reduced inventory costs under the conditions given in the case study.     

Design-unbiased point-to-object sampling on lines,with applications to areal sampling

Sampling methods that depend on the distance between a sample point and a fixed number of objects, such as trees or downed logs, have often been proposed in the forestry and ecology literature. However, such methods have been biased when objects are not distributed with complete spatial randomness, have required difficult field procedures (such as measuring the position of out-of-sample objects), or both. Here a new approach based on measurement of the distance to objects along sample lines is proposed. The approach does not require measuring the position of out-of-sample objects, and its design-unbiased estimators require only simple arithmetic. Furthermore, because many useful sampling procedures can be related back to sampling on a line, the new method leads quickly to sampling procedures applicable when objects are distributed in a two-dimensional region. These include, among others, fixed-count approaches to line intersect sampling, a new approach to variable-area transect sampling, and a density-adapted variable sector sampling method.     

森林分层抽样程序

分层抽样在森林资源二类调查、木材消耗量调查、农村社会经济调查当中都经常应用。本文基于CASIO-4500P机型研制其应用程序，供有关人员参考。     

NON-DESTRUCTIVE SAMPLING FOR YIELD ESTIMATION

AIMThemostcommonmethodforas-sessingtotalbiomassisbydestructive1ysampling,i.e.cuttingdownrandomsam-ples,weighingthem,andextrapo1atingtheresultsfortheentirep1antation.Theesti-matewi1lgenerallybemoreaccuratewithalargersample,butenteringa3-5yearo1dplantationtocutdownshootsanddragthemouttobeweighed,isatime-con-sumingbusiness.Itisthereforenecessarytofindsomereliab1emeansofestimatingbiomassfromparameterswhichcanbeeas-ilymeasuredwhi1etheshootsarestillstanding.Amodelneedstobecreatedtoassessbiomassfirs…     

油松毛虫蛹种群简单随机抽样最适样方大小的确定方法

在种群空间格局研究的基础上，采用7种方法对油松毛虫蛹种群简单随机抽样技术中最适样方大小的确定问题进行了研究。结果是蛹种群在u=1时抽样误差最低，即以单株油松为样方时最为适宜。此外，中还给出了考虑抽样花费时确定最适样方大小的各种方法，并讨论了有关问题。     

SOME PROBLEMS ON FOREST SAMPLING TECHNIQUES

INTRoDUCTIoNForestinventorymaybedefmedastheteeboqu9ofcollecting,evaluatinandpresent-ingspecifiedinformationonforestareas.AstherearemanydtherentsamPlingmethods,achoicemustfirstbemadeastowhichmethodsultsthegivenfieldShoplerandomsamPlingisthebasisofothermethdsandthesamPlingproQedureissimplynamedSRS.WeoftenhavetodealwithPOpulatonthatcanbesplituPintovarioussub-populationthatinsomeresPectofotheraremutUallydifferent,eachsub-populaton(calledstrAn)initSelfthenismorehomoge-nousthanthepopulatio…     

最优经济分层抽样的研究与应用

介绍了最优经济分层抽样的原理及其样本配置方法，并与比例法，最优法进行对比，认为经济分配法是比较好的     

森林冠层节肢动物取样研究进展

冠层节肢动物的研究是近来生物多样性研究的国际前沿，文章主要介绍了森林冠层节肢动物的取样方法，如烟雾杀虫剂击倒法、取样树叶和小枝、非引诱式捕获器、诱捕器及其它取样法，并指出了各类取样法的优缺点。