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201.
Establishing IUCN Red List Criteria for Threatened Ecosystems 总被引:1,自引:0,他引:1
JON PAUL RODRÍGUEZ KATHRYN M. RODRÍGUEZ‐CLARK JONATHAN E. M. BAILLIE NEVILLE ASH JOHN BENSON TIMOTHY BOUCHER CLAIRE BROWN NEIL D. BURGESS BEN COLLEN MICHAEL JENNINGS DAVID A. KEITH EMILY NICHOLSON CARMEN REVENGA BELINDA REYERS TAMMY SMITH MARK SPALDING ANDREW TABER MATT WALPOLE IRENE ZAGER TARA ZAMIN 《Conservation biology》2011,25(1):21-29
Abstract: The potential for conservation of individual species has been greatly advanced by the International Union for Conservation of Nature's (IUCN) development of objective, repeatable, and transparent criteria for assessing extinction risk that explicitly separate risk assessment from priority setting. At the IV World Conservation Congress in 2008, the process began to develop and implement comparable global standards for ecosystems. A working group established by the IUCN has begun formulating a system of quantitative categories and criteria, analogous to those used for species, for assigning levels of threat to ecosystems at local, regional, and global levels. A final system will require definitions of ecosystems; quantification of ecosystem status; identification of the stages of degradation and loss of ecosystems; proxy measures of risk (criteria); classification thresholds for these criteria; and standardized methods for performing assessments. The system will need to reflect the degree and rate of change in an ecosystem's extent, composition, structure, and function, and have its conceptual roots in ecological theory and empirical research. On the basis of these requirements and the hypothesis that ecosystem risk is a function of the risk of its component species, we propose a set of four criteria: recent declines in distribution or ecological function, historical total loss in distribution or ecological function, small distribution combined with decline, or very small distribution. Most work has focused on terrestrial ecosystems, but comparable thresholds and criteria for freshwater and marine ecosystems are also needed. These are the first steps in an international consultation process that will lead to a unified proposal to be presented at the next World Conservation Congress in 2012. 相似文献
202.
The present study simultaneously examined people's perceptions of person–organization (PO) and person–supervisor (PS) fit and related these perceptions to employees' commitments. Three‐hundred‐and‐sixty employee–supervisor dyads from Taiwanese organizations reported about their PO fit and PS fit perceptions. In addition, supervisors reported about their perceptions of fit and guanxi with each of their employees. Results indicated that PO and PS fit perceptions both had an independent and additive relationship with organizational commitment. The link between employee PS fit perceptions and organizational commitment was mediated by commitment to the supervisor. Both employee and supervisor fit perceptions contributed to commitment to the supervisor through their influence on the quality of the leader‐member exchange (LMX). Guanxi could not explain additional variance in LMX and supervisor commitment. Implications for theory and practices regarding person–environment fit, commitment, and LMX are discussed. The study findings offered suggestions for a new Theory of Multiple Fits. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
203.
Individual-based models (IBMs) have been improved in quality and reliability in recent years with an approach called pattern-oriented modelling (POM). POM proposes guidelines to develop models reproducing multiple patterns observed on the field and to test systematically how well the IBMs reproduce them. POM studies used generally traditional methods of goodness of fit such as the sum of squares evaluation or ad hoc comparisons of fitting errors and variations. Model selection, however, can be a rigorous statistical approach based on information theory and information criteria such as the Akaike's information criterion (AIC) or the deviance information criterion (DIC). So far, it has not been tried to link POM to these rigorous techniques. The main problems to achieve that are: (a) the difficulty to have likelihood functions for IBMs’ parameters and (b) the possibility to obtain posterior distributions of IBMs’ parameters given the patterns to reproduce. In a first part, this paper answers problem (a) by proposing and explaining how to calculate a deviance measure (POMDEV) for models developed in a context of POM. And while answering the second problem, a second part of the paper proposes an information criterion for model selection in a POM context (the pattern-oriented modelling information criterion: POMIC). This criterion does not yet have the same theoretical foundation as, e.g., AIC, but uses formal analogies to the DIC. In a third part POMIC is tested with a modelling exercise. This exercise shows the potential of POMIC to use multiple patterns for selecting among multiple potential submodels and eventually select the most parsimonious and well fitting model version. We conclude that POMIC, although being a heuristically derived approach, can greatly improve the POM framework. 相似文献
204.
R. J. Davies‐Colley D. G. Smith 《Journal of the American Water Resources Association》2001,37(5):1085-1101
ABSTRACT: Suspended sediment causes a range of environmental damage, including benthic smothering, irritation of fish gills, and transport of sorbed contaminants. Much of the impact, while sediment remains suspended, is related to its light attenuation, which reduces visual range in water and light availability for photosynthesis. Thus measurement of the optical attributes of suspended matter in many instances is more relevant than measurement of its mass concentration. Nephelometric turbidity, an index of light scattering by suspended particles, has been widely used as a simple, cheap, instrumental surrogate for suspended sediment, that also relates more directly than mass concentration to optical effects of suspended matter. However, turbidity is only a relative measure of scattering (versus arbitrary standards) that has no intrinsic environmental relevance until calibrated to a ‘proper’ scientific quantity. Visual clarity (measured as Secchi or black disc visibility) is a preferred optical quantity with immediate environmental relevance to aesthetics, contact recreation, and fish habitat. Contrary to common perception, visual clarity measurement is not particularly subjective and is more precise than turbidity measurement. Black disc visibility is inter‐convertible with beam attenuation, a fundamental optical quantity that can be monitored continuously by beam transmissometry. Visual clarity or beam attenuation should supplant nephelometric turbidity in many water quality applications, including environmental standards. 相似文献
205.
ABSTRACT: Vermont is one of approximately half a dozen states for which no official drought mitigation plan exists. Given the recurring nature of this natural hazard, current contingency measures should be expanded upon into a coherent mitigation framework. The types of drought and impacts resulting from the 1998 to 1999 event were the focus of a previous article in this volume. The present article builds on the understanding of drought characteristics specific to the Vermont context and introduces the rationale behind a proposed drought planning framework. Pivotal organizations and institutions that should be involved in this process are also presented. 相似文献
206.
Kun‐Yeun Han Sang‐Ho Kim Deg‐Hyo Bae 《Journal of the American Water Resources Association》2001,37(3):695-708
ABSTRACT: This study developed a QUAL2E‐Reliability Analysis (QUAL2E‐RA) model for the stochastic water quality analysis of the downstream reach of the main Han River in Korea. The proposed model is based on the QUAL2E model and incorporates the Advanced First‐Order Second‐Moment (AFOSM) and Mean‐Value First‐Order Second‐Moment (MFOSM) methods. After the hydraulic characteristics from standard step method are identified, the optimal reaction coefficients are then estimated using the Broyden‐Fletcher‐Goldfarb‐Shanno (BFGS) method. Considering variations in river discharges, pollutant loads from tributaries, and reaction coefficients, the violation probabilities of existing water quality standards at several locations in the river were computed from the AFOSM and MFOSM methods, and the results were compared with those from the Monte Carlo method. The statistics of the three uncertainty analysis methods show that the outputs from the AFOSM and MFOSM methods are similar to those from the Monte Carlo method. From a practical model selection perspective, the MFOSM method is more attractive in terms of its computational simplicity and execution time. 相似文献
207.
Wei‐Han Liu Miguel A. Medina Wayne Thomann Warren T. Piver Timothy L. Jacobs 《Journal of the American Water Resources Association》2000,36(6):1335-1348
ABSTRACT: Using a genetic algorithm (GA), optimal intermittent pumping schedules were established to simulate pump‐and‐treat remediation of a contaminated aquifer with known hydraulic limitations and a water miscible contaminant, located within the Duke Forest in Durham, North Carolina. The objectives of the optimization model were to minimize total costs, minimize health risks, and maximize the amount of contaminant removed from the aquifer. Stochastic ground water and contaminant transport models were required to provide estimates of contaminant concentrations at pumping wells. Optimization model simulations defined a tradeoff curve between the pumping cost and the amount of contaminant extracted from the aquifer. For this specific aquifer/miscible contaminant combination, the model simulations indicated that pump‐and‐treat remediation using intermittent pumping schedules for each pumping well produced significant reductions in predicted contaminant concentrations and associated health risks at a reasonable cost, after a remediation time of two years. 相似文献
208.
David Ching‐Fang Shih Chin‐Dee Lee Kin‐Forie Chiou Shi‐Ming Tsai 《Journal of the American Water Resources Association》2000,36(5):1087-1099
ABSTRACT: Water level data at 16 ground water wells and two sea water gauging stations, coupled with barometric measurements in an alluvial plain in the central‐west region of Taiwan, are analyzed using spectral analysis in the time and frequency domains. The semi‐diurnal component from water level station is observed to be the most noticeable signal while the diurnal component is the less distinct signal recorded at the water level stations. Both semidiurnal and diurnal components are coupled with atmospheric pressure measurements. From the atmospheric pressure data, spectral analysis indicates that both the raw and the pressure adjusted water levels are almost in phase and retain the same amplitude in this area. It implies that the effect of pressure variations is not significant for the sea water and ground water level nearby; the astronomical tidal components, as expected, are the main factor causing fluctuation of ocean water and ground water levels in the Choshuihsi alluvial plain. 相似文献
209.
Laboratory leaching tests may be used for source term determination as a basis for risk assessment for soil-groundwater pathways on contaminated sites. In order to evaluate different leaching procedures, batch extraction tests and percolation tests were performed using three reference materials produced from contaminated soil, demolition waste and municipal solid waste incinerator bottom ash. Emphasis was placed on the investigation of the leachability of the heavy metals copper and chromium, polycyclic aromatic hydrocarbons (PAHs) and the anions chloride and sulfate. Significant discrepancies between column experiments and batch/extraction tests were found for the release of PAHs and to a lesser extent for the heavy metals Cu and Cr. Additionally interlaboratory comparisons were conducted based on different leaching tests with the reference materials and evaluated using the criteria of comparability and reproducibility. The best reproducibility was achieved for all investigated substances in column tests. The reproducibility of batch tests was acceptable except for PAHs. The results from the experimental work will help establish standardized and feasible laboratory procedures as fundamental for substance specific risk assessment of contaminated sites. 相似文献
210.
Zhi‐Jun Liu Donald E. Weller Thomas E. Jordan David L. Correll Kathleen B. Boomer 《Journal of the American Water Resources Association》2008,44(3):700-723
Abstract: We present a simple modular landscape simulation model that is based on a watershed modeling framework in which different sets of processes occurring in a watershed can be simulated separately with different models. The model consists of three loosely coupled submodels: a rainfall‐runoff model (TOPMODEL) for runoff generation in a subwatershed, a nutrient model for estimation of nutrients from nonpoint sources in a subwatershed, and a stream network model for integration of point and nonpoint sources in the routing process. The model performance was evaluated using monitoring data in the watershed of the Patuxent River, a tributary to the Chesapeake Bay in Maryland, from July 1997 through August 1999. Despite its simplicity, the landscape model predictions of streamflow, and sediment and nutrient loads were as good as or better than those of the Hydrological Simulation Program‐Fortran model, one of the most widely used comprehensive watershed models. The landscape model was applied to predict discharges of water, sediment, silicate, organic carbon, nitrate, ammonium, organic nitrogen, total nitrogen, organic phosphorus, phosphate, and total phosphorus from the Patuxent watershed to its estuary. The predicted annual water discharge to the estuary was very close to the measured annual total in terms of percent errors for both years of the study period (≤2%). The model predictions for loads of nutrients were also good (20‐30%) or very good (<20%) with exceptions of sediment (40%), phosphate (36%), and organic carbon (53%) for Year 1. 相似文献