Zooplankton proportion estimates from non-uniform sample volumes

The relative abundance of organisms from different taxa provides information about ecosystem health and diversity. When the numbers of sampled organisms are modelled as Poisson counts, and the sample volumes are not uniform, variance for the proportion attributable to each taxon is difficult to compute. We present a method for computing approximate variances for this situation. The point estimates and their standard errors reduce to the standard multinomial maximum likelihood results when sample volumes are uniform. Further, given initial estimates of population densities for the taxa of interest, optimal sample volumes can be computed. The methods are illustrated for zooplankton counts from Andrus Lake, Michigan.     

Beyond the mean: Understanding firm‐level consequences of variability in diversity climate perceptions

We develop and test an organizational‐level model of the consequences of diversity climate for company performance. Drawing from affective events theory and the organizational climate literature, we highlight the role of idiosyncrasies in employees' diversity climate perceptions. Specifically, we consider diversity climate strength (i.e., agreement in employees' climate perceptions) as a boundary condition of diversity climate's organizational‐level effects and expect high climate strength to be particularly beneficial in demographically diverse organizations. Moreover, we introduce collective positive affect as an underlying mechanism of diversity climate's conditional effects on company performance. Hypotheses are tested in a study of 82 German small‐and‐medium‐sized companies with 13,695 surveyed employees. Results show a moderated mediation relationship where diversity climate is only positively related to organizational performance (via collective positive affect) at relatively high diversity climate strength. Although this finding holds for both demographically diverse and homogeneous organizations, post hoc analyses provide initial evidence that a strong climate only helps to realize the effects of diversity climate on collective positive affect when members of age‐ and gender‐related demographic subgroups converge in their climate perceptions. Our study contributes to a better understanding of diversity climate as an effective lever for managing diversity.     

Natural history of crop-related wild species: Uses in pest habitat management

The natural histories of crop-related wild species in their native habitats can be used to develop novel pest management strategies. Traditionally, such information has provided insights for biological control, plant breeding, crop management, and applied ecology Further insights can be garnered.     

IMPACT OF WATERSHED URBANIZATION ON STREAM INSECT COMMUNITIES1

ABSTRACT: The impact of urbanization on stream insect communities was determined by sampling 22 sites in northern Virginia representing a range of human population densities. Watershed development had little effect on the total insect numbers (no./m²), but shifted the taxonomic composition markedly. Relative abundance of Diptera (mainly chironomids) increased at more highly urbanized sites, while most other insect orders including Ephemeroptera (mayflies), Coleoptera (bettles), Megaloptera (dobsonflies), and Plecoptera (stone-flies) decreased. Trichoptera (caddisfiles) exhibited a variable response. Genus diversity and richness (number of genera) were significantly higher in less urbanized streams. Two genera of chironomids were positively correlated with increased urbanization, while 14 other genera (scattered through several orders) were negatively related to human population density. Principal components analysis demonstrated a gradient from more urbanized to less urbanized stations based on generic and order level biological data. Results of this study indicate that watershed urbanization has a major impact on benthic insect communities even in the absence of point source discharges.     

LONGITUDINAL SUCCESSION IN IMPACT ASSESSMENT OF RIVER SYSTEM FISH COMMUNITIES1

ABSTRACT: Longitudinal succession indicates that diversity and species richiess of fish communities increases with increasing river size (increasing habitat complexity and environmental stability). Cultural impacts tend to decrease diversity, species richness, and evenness. To assess the impacts of cultural events on the fish community of a river system, the bias caused by longitudinal succession was removed by normalizing diversity indices and species richness values for river size. The relationships between an impact index and the community parameters of evenness, normalized diversity, and normalized species richness were determined by regression analysis. Similar relationships were determined using nonnormalized data, and the results compared. The two sets of regressions were similar in terms of variance explained. Evenness, which is unaffected by longitudinal sucession, appears to be the most impact sensitive parameter. A major source of error and confusion rsults from introduced species which are simultaneously sources of biological impact and a component of the community. Numbers of introduced species tend to increase with both impact and river size.     

WATER QUALITY AND MACROINVERTEBRATE POPULATIONS BEFORE AND AFTER A HAZARDOUS WASTE CLEANUP1

ABSTRACT: Water samples and macroinvertebrates were collected from Finley Creek, Indiana, both before and two years after the cleanup of a nearby hazardous waste site. Water quality constituents were compared between years. Below the disposal site higher concentrations of constituents were found before and after the cleanup. However, two years after the cleanup, an improvement of water quality was observed. Total dissolved solids decreased by 52% and macroinvertebrate taxa increased by 44%.     

ANALYSIS OF DATA FROM BIOLOGICAL SURVEYS OF STREAMS: DIVERSITY AND SAMPLE SIZE1

ABSTRACT: Brillouin's equation (H) for species diversity from information theory is to be preferred for the purposes of applied ecology over the equation of Shannon (H′) or the more commonly used approximate equation (H″). By its use, the difficult problem of delimiting the extent of the community being sampled in a stream survey can be avoided. Moreover, Brillouin's equation gives the exact diversity of the fully censused collection, whreas Shannon's diversity can only be approximated with a biased estimator. If we regard a sample as a message from the environment to the ecologist, Brillouin's equation is the proper one for computing its diversity. The product moment correlation coefficient between Brillouin's H for the total number of individuals from a group of samples and for randomly chosen subsets of 100 individuals from each sample was nearly as high as the correlation between H and H″ based on the total samples. This indicates that small sample sizes may give a useful diversity index. Replicated subsamples show that much smaller samples than are normally used can discriminate between communities from polluted and unpolluted environments. The use of smaller samples should reduce the cost of stream surveys.     

醌类图谱分析在环境微生物生态测定中的应用

近年来，随着人们对各种非培养微生物测定法的重视，醌类图谱分析作为微生物群体指标已在各种环境中得到了应用．首先是样品的分析测定技术得到了提高，如用硅胶柱代替薄层色谱．醌类图谱分析的特点是能够同时对应微生物生态评价的3个重要指标，即微生物群体结构、生物量及微生物多样性．在结合统计分析的基础上，在土壤、污泥及堆肥等不同环境样品及不同微生物反应过程中，已通过醌类图谱分析对这3个指标在微生物生态系中的变动进行了成功的评价．另外，对C-14同位素标记醌类图谱分析法及醌类图谱分析法在污染物降解中的应用等最新进展也进行了简介．图4表3参43     

昆明市双哨乡户级庭园植物多样性分析

采用参与性生物多样性评估方法 ,在双哨乡植物遗传资源多样性保护利用协会参与下 ,对该乡双桥村 1 1 8户农户的庭园植物多样性进行了调查。结果表明 ,双桥村共有庭园植物 93种 ,包括花卉、蔬菜、果树等 ;有 6 7户农户拥有庭园植物 ,庭园植物多样性在不同农户间存在较大差异 ,6 7户农户中 80 .5 %的农户仅拥有 1～ 9种庭园植物。 1 9.5 %的农户拥有 1 0种以上 ,对庭园植物物种多样性保护的贡献较大。户主的年龄、文化程度和家庭人口等与庭园植物物种多样性密切相关。     

莆田老鹰尖自然保护区森林群落物种多样性的研究

对福建莆田市老鹰尖植物区系和群落物种多样性的调查与分析,结果表明,老鹰尖植物种类丰富,计有维管束植物181科737属1003种(含变种),其中蕨类植物35科72属89种,裸子植物9科18属19种,被子植物137科647属901种;植物区系成分复杂,联系广泛,以热带亚热带成分为主,属、种分别占55.17％和57.48％,其植被为中亚热带向南亚热带过度类型;11个主要森林群落的物种多样性以米槠林为最高,D_(ah)达3.5109,其次为罗浮栲+丝栗栲林和米槠+栲树林,D_(ah)指数值分别达2.8945和2.7854,而篓竹林群落为最低,D_(ah)指数值仅1.0081,群落各层片物种多样性以灌木层为最高,呈灌木>乔木层>草本>藤本的变化趋势,说明老鹰尖的水热资源较为丰富。