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排序方式: 共有148条查询结果,搜索用时 31 毫秒
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Helen M. Regan Clara I. Bohórquez David A. Keith Tracey J. Regan Kurt E. Anderson 《Conservation biology》2017,31(2):459-468
Population viability analysis (PVA) is a reliable tool for ranking management options for a range of species despite parameter uncertainty. No one has yet investigated whether this holds true for model uncertainty for species with complex life histories and for responses to multiple threats. We tested whether a range of model structures yielded similar rankings of management and threat scenarios for 2 plant species with complex postfire responses. We examined 2 contrasting species from different plant functional types: an obligate seeding shrub and a facultative resprouting shrub. We exposed each to altered fire regimes and an additional, species‐specific threat. Long‐term demographic data sets were used to construct an individual‐based model (IBM), a complex stage‐based model, and a simple matrix model that subsumes all life stages into 2 or 3 stages. Agreement across models was good under some scenarios and poor under others. Results from the simple and complex matrix models were more similar to each other than to the IBM. Results were robust across models when dominant threats are considered but were less so for smaller effects. Robustness also broke down as the scenarios deviated from baseline conditions, likely the result of a number of factors related to the complexity of the species’ life history and how it was represented in a model. Although PVA can be an invaluable tool for integrating data and understanding species’ responses to threats and management strategies, this is best achieved in the context of decision support for adaptive management alongside multiple lines of evidence and expert critique of model construction and output. 相似文献
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The placement of 1918 redwing nests has been analyzed, including 214 nests of 90 marked females (2–8 known nests per female). A high level of intraspecific and individual variation in utilization of different types of nest supports is described. It is shown that redwings choose nest sites without regard to previous experience (either positive or negative) or to the placement of their parent nest. Under conditions of the northern taiga, such behavior provides for significant reduction of chick mortality by the end of the season. This is con- firmed by comparison with the song thrush (T. philomelos), which nests mainly on spruce trees. 相似文献
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H. B. Osborn L. J. Lane R. S. Kagan 《Journal of the American Water Resources Association》1971,7(3):484-494
ABSTRACT Significant parameters for predicting thunderstorm runoff from small semiarid watersheds are determined using data from the Walnut Gulch watershed in southern Arizona. Based on these data, thunderstorm rainfall is dominant over watershed parameters for predicting runoff from multiple linear regression equations. In some cases antecedent moisture added significantly to the models. A technique is developed for estimating precision of predicted values from multiple linear regression equations. The technique involves matrix methods in estimating the variance of mean predicted values from a regression equation. The estimated variance of the mean predicted value is then used to estimate the variance of an individual predicted value. A computer program is developed to implement these matrix methods and to form confidence limits on predicted values based on both a normality assumption and the Chebyshev inequality. 相似文献
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Bohdan Dudek Jerzy Koniarek 《International journal of occupational safety and ergonomics》2013,19(2):118-129
Subjective rating scales for measuring work demands and individual capabilities to cope with work requirements were developed using the Thurstonian procedure. The scales measure six dimensions of mental workload: mental difficulties, feeling of responsibility, awareness of risk, interpersonal conflicts, monotony, and time pressure. Individual scale results make it possible to assess the level of mental workload understood as a relation between the subjective rating of work demands and individual capabilities in each of the six dimensions. Two versions of scales were prepared: classic and modified ones. To assess the level of reliability of the particular scales, 481 participants were examined twice at a 1-month interval. A procedure to prepare scales for the measurement of other dimensions of mental workload is also presented. 相似文献
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跟踪拍照识别白鱀豚的研究 总被引:1,自引:0,他引:1
作者从1986年起开展了照相识别白豚的研究。通过反复试验,采用多船弧形跟踪、单船切入拍照的方法,在观察到白豚的48天中,共拍得1600张照片并从中识别出10头白暨豚。除了白暨豚背鳍上的自然标记能有效地用于个体识别之外,豚体上的色斑、图象等亦能用于个体识别。作者由此获得了白豚群体组成变化和迁移距离等科学资料,对深入研究白暨豚生态学有重要意义。 相似文献
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天然气管道失效个人生命风险评价技术研究 总被引:1,自引:0,他引:1
为研究天然气长输管道失效个人生命风险,提出一种以人员伤亡概率为指标的天然气管道失效后果风险评价方法。基于天然气管道的失效概率和失效致死长度参数,建立天然气长输管道生命风险评价模型。用该模型,对国内某城市住宅小区内带腐蚀缺陷的天然气管线进行定量风险分析。借鉴英国天然气输送公司数据,确定天然气管线个人生命风险值。案例证明,用所建立的天然气管道失效个人生命风险评价模型能够有效地分析带缺陷天然气管道失效后果,实现天然气管道的个人安全生命风险全定量评价。 相似文献
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Steven R. Beissinger Jason G. Bragg David J. Coates J. Gerard B. Oostermeijer Paul Sunnucks Nathan H. Schumaker Meredith V. Trotter Andrew G. Young 《Conservation biology》2015,29(3):755-764
We examined how ecological and evolutionary (eco‐evo) processes in population dynamics could be better integrated into population viability analysis (PVA). Complementary advances in computation and population genomics can be combined into an eco‐evo PVA to offer powerful new approaches to understand the influence of evolutionary processes on population persistence. We developed the mechanistic basis of an eco‐evo PVA using individual‐based models with individual‐level genotype tracking and dynamic genotype–phenotype mapping to model emergent population‐level effects, such as local adaptation and genetic rescue. We then outline how genomics can allow or improve parameter estimation for PVA models by providing genotypic information at large numbers of loci for neutral and functional genome regions. As climate change and other threatening processes increase in rate and scale, eco‐evo PVAs will become essential research tools to evaluate the effects of adaptive potential, evolutionary rescue, and locally adapted traits on persistence. 相似文献