Planning for success: Identifying effective and efficient survey designs for monitoring

Selecting a survey design to detect change through time in an ecological resource requires balancing the speed with which a given level of change can be detected against the cost of monitoring. Planning studies allow one to assess these tradeoffs and identify the optimal design choices for a specific scenario of change. However, such studies seldom are conducted. Even worse, they seem least likely to be undertaken when they offer the most insight – when survey methods and monitoring designs are complex and not well captured by simple statistical models. This may be due to limited technical capacity within management agencies. Without such planning, managers risk a potentially severe waste of monitoring resources on ineffective and inefficient monitoring, and institutions will remain ignorant of the true costs of information and the potential efficiency gains afforded by a moderate increase in technical capacity. We discuss the importance of planning studies, outline their main components, and illustrate the process through an investigation of competing designs for monitoring for declining brown bear (Ursus arctos) densities in southwestern Alaska. The results provide guidance on how long monitoring must be sustained before any change is likely to be detected (under a scenario of rather strong true decline), the optimal designs for detecting a change, and a tradeoff where accepting a delay of 2 years in detecting the change could reduce the monitoring cost by almost 50%. This report emphasizes the importance of planning studies for guiding monitoring decisions.     

A method of processing soil core samples for root studies by subsampling

Root studies are generally believed to be very important in ecological research. Soil coring is a valuable approach to root research, but it requires a very large amount of processing time. We present here a method for processing soil cores consisting of the combination and homogenization of several soil cores from a plot, with subsequent subsampling for root extraction. The required subsample size was determined for a topsoil and a subsoil sample from a groundnut field and was found to be 5–10% of the total soil sample. Advantages and limitations of the method are discussed.     

两元件串联可修系统的计算机模拟分析

研究了典型的两元件串联的可修系统,在已知元件的寿命分布的条件下,应用蒙特卡罗方法,对元件的寿命进行随机抽样并进行计算机模拟,通过统计每个元件故障的次数,得出了两元件串联可维修系统的可靠性特征量——故障率,并绘出了曲线。     

基于样点个体代表性的大尺度土壤属性制图方法

大空间尺度范围的土壤属性分布信息是陆地表层过程模拟的基础信息.基于野外样点进行空间插值是获得土壤属性空间分布信息的重要手段.现有的空间插值方法通常要求所用样点对研究区土壤属性空间分布规律具有良好的全局代表性.然而,受采样经费和野外采样条件的限制,所采集的样点往往难以全面地反映研究区土壤属性的空间分布规律.基于这样的样点用现有空间插值方法得到的土壤属性分布图通常精度较低,并且由样点全局代表性差带来的推测不确定性也无法得到度量.为了合理利用这些已采集的但全局代表性不好的样点,本文提出了基于样点“个体代表性”推测土壤属性空间分布并度量推测不确定性的方法.该方法在两点环境条件越相似、土壤属性就越相似的假设下,认为每一样点可以代表与其环境条件相似的地区,并且代表程度可以由两点的环境相似度度量;通过分析环境相似度计算推测不确定性,并以环境相似度为权重计算样点可代表地区的土壤属性值.将该方法应用于推测新疆伊犁地区土壤表层有机质含量,经验证,本文方法能够有效地利用全局代表性差的样点推测样点能够代表地区的土壤属性空间分布,并且所得的推测不确定性与预测残差呈现正向关系,能够有效地指示推测结果的可靠程度.     

Analysis of sampling strategies to substantiate freedom from disease in large areas

In this paper, we deal with the strategies of surveys to substantiate freedom from disease for a certain territory. Infection might not be distributed homogeneously. So, a relatively high within-herd prevalence might be observed while the herd-level prevalence is lower. For this situation, we compare various two-stage sample strategies.

The calculation of appropriate sample sizes becomes quite complicated. The theoretical generalization of the hypergeometric distribution by Cameron and Baldock [Prev. Vet. Med. 24 (1998) 1] introduces a simple way to evaluate multi-stage sample sizes while regarding real-test properties. We demonstrate the theoretical foundations of these calculations. These principles open up the possibility of optimizing costs or other relevant variables, by choosing the appropriate sample strategy (each of which ensures the same -level for the first stage). In addition, we evaluate the statistical power of the complete strategies under consideration.

Furthermore, we apply our theoretical results to a data example of Brucella melitensis. We used the herd-size situation in Germany, characterized by many small sheep holdings and only a few large ones. The consequences of real-test properties on sample sizes and on the applicability of several strategies are discussed.     

抽样方法在国土资源监测中的应用

为解决已有监测项目监测周期长、反馈速度慢、监测数据失真、监测内容单一等问题,安徽省国土资源监测项目在技术路线设计时,通过对4种常用抽样方法的对比分析,提出一种复合抽样方法——多阶段分层随机抽样方法。抽样方法的应用,改变了传统监测理念,以抽样监测代替全面调查,以第三方动态监测代替系统内静态监测,以决策支撑导向代替查处问责机制,保证监测数据及时、准确、有效的应用,节约大量人力物力,为国土资源管理和利用监管提供了新的思路。     

Evaluation of sample pre-treatment and potential contamination of soluble carbon in soil extracts during lyophilisation

Lyophilisation of K₂SO₄ soil extracts has been proposed as a sample preparation technique before elemental analysis of carbon or nitrogen. However, previous measurements, based on wet oxidation or catalytic combustion, indicated that C measurements in lyophilised samples not always proved to be accurate. To determine whether the C analysis was affected by the lyophilisation process, an exploratory study was conducted to investigate the potential effects of the sample pre-treatment and of the lyophilisation process itself. This paper puts forward that the use of soil extracts, previously stored at −20 °C, may affect the recovery of salt in the samples and that contamination of the soluble carbon with exogenous C during lyophilisation is feasible. Therefore we recommend to use freshly prepared soil extracts for lyophilisation and always to include an internal standard among the unknown samples to account for a possible contamination.     

作物叶片蛋白质组提取与酶切方法比较研究

蛋白质组样品制备主要涉及蛋白质的提取和酶切处理,是蛋白质组学分析的限制环节之一。为了提高作物叶片蛋白质组样品制备的效率和重复性,系统比较了6种缓冲液（pH8.5 Tris-HCl酚、pH7.0磷酸盐、pH9.0碳酸盐、尿素/硫脲、pH8.0 Tris-HCl、pH4.5醋酸盐）和TCA-丙酮处理对水稻、小麦、大豆和玉米叶片蛋白质提取的影响,同时以小麦叶片总蛋白和牛血清白蛋白为样本,比较了传统方法和微波辅助方法的酶切效率。结果表明,TCA-丙酮处理的小麦和水稻样品采用尿素/硫脲方法能获得较高的蛋白得率,而玉米和大豆样品采用尿素/硫脲直接提取时蛋白质得率更高,同时,微波辅助酶切值得用于蛋白质组样品制备。本研究采用适当的蛋白质提取和酶切方法,有效提高了蛋白质的提取率和鉴定率,可为进一步深入开展作物叶片的蛋白质组学研究提供借鉴。     

基于成土环境地理邻域分析的历史土壤图训练样本筛选

基于历史土壤图的知识挖掘和历史图更新对土壤资源调查、管理和利用有着重要的现实意义,而从历史土壤图中筛选代表性训练样本是进行知识挖掘和历史土壤图更新的关键步骤。以安徽省旌德县为研究区,提出一种新的土壤图训练样本筛选方法,包括样本数量确定和样本位置筛选。研究结果表明,面积分段线性缩放法确定的样本数量解决了已有研究未考虑同一类型多个图斑单元间样本数量分配的问题;采用邻域分析方法确定样本位置,当图斑位于地势平缓的区域时,基于高程因子和坡度因子确定的样本空间分布差异较小,而当图斑位于山区时,基于坡度因子确定的样本处于地形变化稳定的位置,全局代表性更高。通过与已有研究中环境因子直方图方法筛选样本进行对比,邻域分析方法确定的样本具有更高的差异比例和标准差,样本信息量更大。基于坡度因子采用邻域分析方法筛选出的图斑样本较高程因子样本拥有更高的全局空间代表性,邻域分析方法筛选的样本较相关研究中环境因子直方图方法筛选的样本拥有更高的信息量。     

水晶花烛的无菌播种和组培快繁技术研究

无菌播种水晶花烛Anthurium crystallinum种子获得无菌苗,取该无菌苗的带节茎段、叶片、叶柄为外植体,研究不同诱导培养基组成对水晶花烛愈伤组织诱导分化的影响,同时对影响水晶花烛芽体增殖和壮苗生根的主要因子进行研究。结果表明:水晶花烛种子较好的灭菌方法:种子经去果皮处理+0.1%升汞消毒8min;外植体愈伤诱导分化以带节茎段为宜,培养基为1/3MS+6-BA1.0mg·L~(-1)+2,4-D 0.3mg·L~(-1);芽体增殖培养基:MS+6-BA 2.0mg·L~(-1)+NAA 0.3mg·L~(-1);壮苗生根培养基:MS+NAA 0.2mg·L~(-1),其移栽成活率可达95%以上。