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11.
Ted L. Ernst Nancy C. Leibowitz Denis Roose Steve Stehman N. Scott Urquhart 《Environmental management》1995,19(1):99-113
The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) will monitor the
nation's resources by evaluating the status and trends of selected indicators of condition using a probability-based sampling
design. The EMAP-Wetlands program will monitor the condition of the nation's wetlands. The EMAP classification system is an
aggregation of the many subclasses of the US Fish and Wildlife Service's National Wetlands Inventory (NWI) classification
system. This aggregation results in fewer wetland classes with more wetlands per class than the NWI system. Aggregation of
the NWI classification was based primarily on dominant vegetation cover, flooding regimes, dominant water source, and adjacency
to rivers and lakes. We evaluated the EMAP classification system and sampling design using NWI digital wetlands data for portions
of Illinois, Washington, North Dakota, and South Dakata. Relative numbers of wetlands, total areas, average areas, and common
versus rare classes were compared between the EMAP and NWI classification systems. As expected, the EMAP classification provided
fewer wetland polygons, each with larger areas, without altering total wetland area. Summary statistics comparing sample estimates
to true population parameters (represented by the NWI data) demonstrated the effectiveness of the EMAP sampling design with
the exception of rare EMAP classes in the selected regions. Although simple random sampling is inadequate for both large and
small wetlands, the EMAP sampling design is readily adapted to provide better estimates for these categories. Aggregating
the NWI classification to the EMAP classification provides fewer wetland classes, with more wetlands per class, for EMAP's
annual reports and statistical summaries.
The research in this report has been funded by the United States Environmental Protection Agency (EPA) under contracts 68-C8-0006
to ManTech Environmental Technology, Inc. and 68-03-3532 to The Bionetics Corporation. Mention of trade names does not constitute
endorsement or recommendation for use. 相似文献