Weight-of-Evidence (WOE): Quantitative Estimation of Probability of Impairment for Individual and Multiple Lines of Evidence

Environmental decision-making is complex and often based on multiple lines of evidence. Integrating the information from these multiple lines of evidence is rarely a simple process. We present a quantitative approach to the combination of multiple lines of evidence through calculation of weight-of-evidence, with reference conditions used to define a not impaired state. The approach is risk-based with measurement of risk computed as the probability of impairment. When data on reference conditions are available, there are a variety of methods for calculating this probability. Statistical theory and the use of odds ratios provide a method for combining the measures of risk from the different lines of evidence. The approach is illustrated using data from the Great Lakes to predict the risk at potentially contaminated sites.     

Determination of diagnostic species with statistical fidelity measures

Abstract. Statistical measures of fidelity, i.e. the concentration of species occurrences in vegetation units, are reviewed and compared. The focus is on measures suitable for categorical data which are based on observed species frequencies within a vegetation unit compared with the frequencies expected under random distribution. Particular attention is paid to Bruelheide's u value. It is shown that its original form, based on binomial distribution, is an asymmetric measure of fidelity of a species to a vegetation unit which tends to assign comparatively high fidelity values to rare species. Here, a hypergeometric form of u is introduced which is a symmetric measure of the joint fidelity of species to a vegetation unit and vice versa. It is also shown that another form of the binomial u value may be defined which measures the asymmetric fidelity of a vegetation unit to a species. These u values are compared with phi coefficient, chi‐square, G statistic and Fisher's exact test. Contrary to the other measures, phi coefficient is independent of the number of relevés in the data set, and like the hypergeometric form of u and the chi‐square it is little affected by the relative size of the vegetation unit. It is therefore particularly useful when comparing species fidelity values among differently sized data sets and vegetation units. However, unlike the other measures it does not measure any statistical significance and may produce unreliable results for small vegetation units and small data sets. The above measures, all based on the comparison of observed/expected frequencies, are compared with the categorical form of the Dufrêne‐Legendre Indicator Value Index, an index strongly underweighting the fidelity of rare species. These fidelity measures are applied to a data set of 15 989 relevés of Czech herbaceous vegetation. In a small subset of this data set which simulates a phytosociological table, we demonstrate that traditional table analysis fails to determine diagnostic species of general validity in different habitats and large areas. On the other hand, we show that fidelity calculations used in conjunction with large data sets can replace expert knowledge in the determination of generally valid diagnostic species. Averaging positive fidelity values for all species within a vegetation unit is a useful approach to measure quality of delimination of the vegetation unit. We propose a new way of ordering species in synoptic species‐by‐relevé tables, using fidelity calculations.     

Distribution of soil invertase in relation to the root systems ofPicea sitchensis (Bong.) Carr. andAcer pseudoplatanus L. during development of young plants

A method is described for sampling rhizosphere soil under newly establishedPicea sitchensis andAcer pseudoplatanus. The technique involves taking soil samples to a depth of 150 mm at 100 mm intervals along transects, each 45° from its neighbour, radiating from the base of the stem. Invertase activities were measured in the soil samples and compared to their activities in fallow and rhizosphere soils. When the field soil was dry, the tree root systems were carefully excavated to retain as many fine roots as possible. The distribution of the soil invertase was matched to the spatial distribution of the roots showing the precise position of the rhizosphere relative to the initial blind soil sampling. Statistics were applied to derive equations for calculating the percentage enzyme activity relative to that found in rhizosphere soil at various locations radiating from the base of the stem. This information was subsequently applied to soil sampled under trees of the same age as those excavated to give a non-destructive method for sampling rhizosphere soil routinely from under a large number of trees.     

不同产地华中五味子叶表皮结构和导管分子的解剖学特征及其与环境因子的关系

在光学显微镜下观察了不同产地华中五味子(Schisandra sphenanthera Rehd.et Wils．)叶表皮结构和导管分子特征,应用多元回归方法对不同产地华中五味子的叶表皮特征及导管分子特征与环境因子的关系进行了分析。观察的指标有叶表皮特征(气孔器密度、气孔器指数、气孔器长宽、气孔器面积、气孔极区角质加厚、气孔器类型、表皮细胞垂周壁形状、分泌细胞密度及叶表面角质条纹)和导管分子特征(导管分子长度、直径、长／直径比值及穿孔板类型)。观察结果：上表皮有极少量气孔器和分泌细胞分布。在下表皮,气孔器类型为平列型和侧列型,气孔器指数为15．05％-22．53％,气孔器长59．2—74．2μm,气孔器宽37．9—46．8μm,分泌细胞密度为1．45／mm^2-3．99／mm^2。导管分子以具缘纹孔导管为主,穿孔板包含单穿孔和梯状穿孔板。导管分子长957．8—1270．2μm,导管分子直径85．0—136．7μm。随着产地的不同,华中五味子叶下表皮结构和导管分子的解剖特征有明显的差异。分析结果显示：年均气温与气孔器面积和气孔器长度,年降水量与气孔器宽度以及相对湿度与分泌细胞密度之间关系密切。随着年平均气温的升高,气孔器面积、气孔器长度呈减少的趋势,R^2值分别为0．74、0．71。随着年降水量的增加,气孔器宽呈减小的趋势,R^2值为0．64;导管分子长／直径比值增加,R^2值为0．46。相对湿度与分泌细胞密度呈正相关,R^2为0．63。     

Quantitative Analysis of Genera Endemic to China

Chinese flora with many endemic elements is highly important in the world’s flora. According to recent statistics there are about 196 genera of spermatophytes, being 6.5% of total Chinese genera. These endemic genera comprising 377 species belong to 68 families, among which the Gesneriaceae (28 genera), Umbelliferae (13), Compositae (13), Orchidaceae (12) and Labiatae (10) are predominant. The tropical type containing 24 families and 80 genera is dominant. After it follows the temperate type with 23 families and 50 genera. There are also 4 families endemic to China, i.e. Ginkgoaceae, Bretschneideraceae, Eucommiaceae and Davidiaceae. It shows that genera endemic to China are obviously related to the tropical and temperate flora in essence. The endemic monotypic genera (139) and endemic obligotypic genera (48) combined make up more than 95% of the total number of genera endemic to China. Phylogenetically more than half of them are ancient or primitive. The life forms of all endemic genera are also diverse. Herbs, especially perennial herbs, prevail with the proportion of about 62%, and trees and shrubs are the next, with 33%, and the rest are lianas. Based upon the calculated number of genera endemic to China in each province and the similarity coefficents between any two provinces, some conclusions may be drawn as follows: Yunnan and Sichuan Provinces combined are the distribution centre of genera endemic to China and may be their original or differentiation area, because numerous endemic genera, including various groups, exist in these two provinces. The second is Guizhou where there are 62 endemic genera. Others form a declining order, south China, central China and east China. But towards the north China endemic genera decrease gradually, and the Qinling Range is an important distributional limit. The largest simitarity coefficient, over 50%, appears between Shaanxi and Gansu probably because of the Qinling Range linking these two provinces. But between any other two provinces it is less than 30% and it is generaly larger between two south provinces than between two north provinces. These characteristics mentioned above are correlated with topography and climate, and they may be resulted from the diversification in geography and climatic influence for a long time.     

Stereological and biochemical analysis of prolactin and growth hormone secreting rat pituitary cells in culture

Summary The secretion of prolactin is increased by treatment of prolactin producing rat pituitary cells with the hypothalamic tripeptide thyroliberin. To investigate the underlying mechanisms we used three closely related rat pituitary tumor cell strains (GH₁2C₁, GH₃ and GH₄C₁), which synthesize and spontaneously secrete prolactin and/or growth hormone. Growth hormone and prolactin released into the culture medium over a period of 24 h were measured by radioimmunoassay. Initial rates of synthesis were measured by immunoprecipitation of intracellular growth hormone and prolactin after incubation of cell cultures with ³H-leucine. The observed increase in prolactin synthesis and release was correlated with morphological effects of thyroliberin treatment. The volume density of Golgi complexes and the volume and surface densities of rough endoplasmic reticulum were compared in untreated cells and thyroliberin treated cells. As normal distribution could not be assumed, the non-parametric rank test of Wilcoxon was used whereby the densities calculated for each cell section were ranked. Alle three morphological parameters increased after thyroliberin treatment in cells secreting prolactin only (GH₄C₁), implying that the increase of prolactin secretion, at lest in part, is due to increased prolactin synthesis.     

Dispersal ability of marked,irradiated olive fruit flies [Bactrocera oleae (Rossi) (Diptera: Tephritidae)] in arid regions

The dispersal of marked, irradiated olive fruit flies originating from a hybrid laboratory strain was studied in an olive groove located in the arid regions of southern Israel. Release–recapture experiments (eight in total) were conducted throughout a period of 5 months (July–December 2008). In each experiment, ca. 5000 flies were released. Recapture of flies was conducted using a grid of 30 yellow sticky traps set in expanding semicircles from the centre of release. Service of traps was conducted 3 and 15 days after the release. Fly quality and adult food type (only sucrose and protein + sucrose) before release was also investigated. Results point at an average dispersal distance of marked, irradiated olive flies of ca. 50 m. Pre‐release adult diet did not affect dispersal ability. Fly recovery averaged ca. 3.5% during summer and ca. 1.5% during autumn. Most of the recovery concentrated during the first 3 days after releases, suggesting low survival of the released flies afterwards. As inferred from circular statistics, direction of dispersal was non‐random with a significant directionality to the north‐west. Results are discussed in view of environmental temperatures and wind direction.     

The effect of intraspecific sample size on type I and type II error rates in comparative studies

Comparative studies have increased greatly in number in recent years due to advances in statistical and phylogenetic methodologies. For these studies, a trade-off often exists between the number of species that can be included in any given study and the number of individuals examined per species. Here, we describe a simple simulation study examining the effect of intraspecific sample size on statistical error in comparative studies. We find that ignoring measurement error has no effect on type I error of nonphylogenetic analyses, but can lead to increased type I error under some circumstances when using independent contrasts. We suggest using ANOVA to evaluate the relative amounts of within- and between-species variation when considering a phylogenetic comparative study. If within-species variance is particularly large and intraspecific sample sizes small, then either larger sample sizes or comparative methods that account for measurement error are necessary.