A theoretical study of the bulk breeding method

Summary The consequences of sampling losses that occur with the bulk breeding method are studied. The expected extinction rates are computed for various population sizes and various distributions of the number of seeds per plant (multiplication rates), using algebraic formulas in simple cases and computer simulations in more complex ones. Expected extinction rates are always high: they exceed 20 per cent after one generation. If the multiplication rate is not too variable, about 36, 50, 60 and 66 per cent of the lines are lost after 1, 2, 3 and 4 generations of bulk propagation respectively. The expected extinction rate increases almost linearly with the coefficient of variation of the multiplication rate after the first generation of bulk propagation. Random losses only partially add to sampling losses. Their effect is enhanced by a high coefficient of variation of the multiplication rate, but it is more and more reduced as generations advance.The selection resulting from sampling is also studied. It is shown that the response to selection is equal to the response that would be observed in a truncation selection procedure with an intensity equal to the coefficient of variation of the heritable component of the multiplication rate.Abbreviations BK bulk breeding - SSD single seed descent - HD haplodiploidization     

枣步曲幼虫空间分布型及抽样技术的研究

通过ＩｗａｏＸ－Ｘ回归测定，枣步曲幼虫的空间分布为奈曼－Ａ型分布或波松－二项分布，分布的基本成分为致密的个体群，个体群间及个体群内的分布均为随机分布，个体群的面积小于或等于１株树，对于估值抽样提出了两种方案，即整体抽样和层抽样，前者以随机抽样和棋盘式抽样为优，并给出了理论抽样公式，后者以最下层抽样代替整株抽样估计种群密度，可以提高抽样效率，降低抽样费用，且估计精度能达到科研与生产的要求，最后给出Ｉ     

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.     

电子角规用于3P抽样测定林分蓄积的研究

3P抽样是在林业界较早得到认可的一种森林蓄积量调查手段,但由于传统的森林资源监测技术不能解决立木材积精准监测及快速生成随机数这两个关键问题而未能得到广泛应用。电子角规实现了立木材积的精准测定,测定方法采用的是中央断面区分求积法,配合开发的相应3P抽样程序,可以对应于辅助因子产生随机数,从而使3P抽样过程变得简便易行。在甘肃小陇山林业局党川林场进行了针对性实验,取得了较高的林分蓄积监测精度。     

Adaptive cluster sampling for estimation of deforestation rates

National estimates of deforestation rates may be based on a survey. Precise estimation requires an efficient design. When deforestation rates are low (<1%) large sample sizes are required with traditional sampling designs to meet a precision target. This study explores the efficiency of adaptive cluster sampling (ACS) for this estimation problem. The efficiency is assessed by simulated ACS sampling from 18,200 × 200 km populations with 78–10,742 deforestation polygons (DFP) of different shape and size and average 10-year deforestation rates between 0.2% and 1.0%. Each population is composed of four million square 1 ha population units (PU) in a regular grid. Relative root mean square errors (RMSE) of ACS were, depending on sample size, 30–50% lower than comparable errors with simple random sampling (SRS) designs. ACS achieves this advantage by adaptively adding PUs to an initial SRS sample of size n. Realized ACS sample sizes were, on average, twice the nominal size (n). Three measures of ACS efficiency indicated that the costs of adaptively increasing the sample size are critical for the effectiveness of ACS. Population effects were manifest in all estimators. Estimates of the abundance, size, and shape of DFPs will allow a prediction of these effects. Populations dominated by a few large DFPs were clearly unsuited for ACS. The performance of ACS relative to that of SRS was similar across plot sizes of 1, 10, and 40 ha. The general conclusion of this study is that the lower RMSE of ACS remains attractive when the average cost of adaptively adding a PU to the initial sample is low relative to the average cost of sampling a PU at random.     

鞭角华扁叶蜂滞育期幼虫空间分布型及抽样技术研究

鞭角华扁叶蜂滞育期幼虫空间分布型及抽样技术研究＊郑永祥崔相富吴道圣杨胜利陈绘画关键词鞭角华扁叶蜂、滞育期幼虫、空间分布、抽样技术鞭角华扁叶蜂［Ｃｈｉｎｏｌｙｄａｆｌａｇｅｌｉｃｏｒｎｉｓ（Ｆ．Ｓｍｉｔｈ）］属膜翅目（Ｈｙｍｅｎｏｐｔｅｒａ）、扁叶蜂科...     

栗瘿蜂虫瘿空间格局的研究

采用聚集度指标方法，对栗瘿蜂虫瘿在锥栗林中的空间格局进行测定。结果表明，栗瘿蜂虫瘿在锥栗林中为聚集分布，分布的基本成分是个体群。同时分析了其聚集原因，计算了林间调查的最适抽样数，列出了序贯抽样分析表，为林间抽样调查及防治提供了依据。     

A method for axenic sampling of wood from standing trees

A method is described to collect wood samples axenically from standing trees by the use of a Pressler borer in conjunction with protective sterile jackets.     

杉木球果瘿蚊虫果空间分布型及抽样技术之初步研究

杉木球果瘿蚊虫果空间分布经３类分析方法检验均显示为聚集；杉木树冠部位对虫果率无显著影响，虫果率调查抽样方式以平行线抽样较适合；抽样数据的统计代换可采用对数代换［Ｘ＇＝Ｉｎ（Ｘ＋１）］或Ｔａｙｌｏｒ的方法（Ｘ＇＝Ｘ－０．２５８５）。     

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。