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Many problems and challenges of ecosystem management currently are driven by the rapid pace and spatial extent of landscape
change. Parks and reserves within areas of high human population density are especially challenged to meet the recreational
needs of local populations and to preserve valued environmental resources. The complex problem of managing multiple objectives
and multiple resources requires an enormous quantity of information, and conceptual models have been proposed as tools for
organizing and interpreting this information. Academics generally prefer a bottom-up approach to model construction that emphasizes
ecologic theory and process, whereas managers often use a top-down approach that takes advantage of existing information to
address more pragmatic objectives. The authors propose a formal process for developing, applying, and testing conceptual models
to be used in landscape monitoring that reconciles these seemingly opposing perspectives. The four-step process embraces the
role of hypothesis testing in the development of models and evaluation of their utility. An example application of the process
to a network of national parks in and around Washington, DC illustrates the ability of the approach to systematically identify
monitoring data that would both advance ecologic theory and inform management decisions. 相似文献
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Shouliang Huo Chunzi M Beidou Xi Yali Zhang Fengchang Wu Hongliang Liu 《环境科学学报(英文版)》2018,30(5):54-66
Nutrient criteria provide a scientific foundation for the comprehensive evaluation, prevention,control and management of water eutrophication. In this review, the literature was examined to systematically evaluate the benefits, drawbacks, and applications of statistical analysis,paleolimnological reconstruction, stressor-response model, and model inference approaches for nutrient criteria determination. The developments and challenges in the determination of nutrient criteria in lakes and reservoirs are presented. Reference lakes can reflect the original states of lakes, but reference sites are often unavailable. Using the paleolimnological reconstruction method, it is often difficult to reconstruct the historical nutrient conditions of shallow lakes in which the sediments are easily disturbed. The model inference approach requires sufficient data to identify the appropriate equations and characterize a waterbody or group of waterbodies, thereby increasing the difficulty of establishing nutrient criteria. The stressor-response model is a potential development direction for nutrient criteria determination, and the mechanisms of stressor-response models should be studied further. Based on studies of the relationships among water ecological criteria, eutrophication, nutrient criteria and plankton, methods for determining nutrient criteria should be closely integrated with water management requirements. 相似文献
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Missing covariate values in linear regression models can be an important problem facing environmental researchers. Existing
missing value treatment methods such as Multiple Imputation (MI), the EM algorithm and Data Augmentation (DA) have the assumption that both observed and unobserved data come from the same distribution,
most commonly a multivariate normal or a conditionally multivariate normal family. These methods do try to incorporate the
missing data mechanism and rely on the assumption of Missing At Random (MAR). We present a DA method which does not rely on
the MAR assumption and can model missing data mechanisms and covariate structure. This method utilizes the Gibbs Sampler as
a tool for incorporating these structures and mechanisms. We apply this method to an ecological data set that relates fish
condition to environmental variables. Notice that the presented DA method detects relationships that are not detected when
other missing data methods are employed.
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Edward L. BooneEmail: |
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