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Title: An investigation into the best method to combine national and local data to develop site-specific critical loads
Author: R. Wadsworth
Author: J.. Hall
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1371, Representation ID: 458, Object ID: 2530
Critical loads provide national or European-wide maps of the sensitivity of habitats to acidification or eutrophication which are used in effects-based policy development. Although such maps are appropriate for national-scale assessments, this may not be the case for site-specific assessments due to assumptions and the resolution of the underlying datasets. At the site level, insufficient data or effects criteria generally exist to calculate critical loads for specific habitats or species. The aim of this study was to present a new and alternative method for carrying out site-specific acidity critical loads assessments based on developing the relationships between vegetation communities, soil types and critical loads. This has been achieved by the application of Endorsement Theory a a non-numeric, qualitative approach. It provides an endorsement based on the aweight of evidencea for different critical load values for the vegetation communities of the National Vegetation Classification (NVC), which are often used to describe the habitats of designated sites. In addition, a DempsteraShafer formalism is proposed that combines and refines the estimates of critical loads derived from both the national maps and from the endorsement. The full methodology is described in this report, which is accompanied by a MicrosoftA Access database containing the underlying datasets, endorsement tables and queries to automatically generate summary or critical load endorsement reports for any selected NVC community. Aquatic vegetation communities are not covered by this study. The report discusses the results in the context of the 22 heathland NVC communities in the UK. Heathland communities of one sort or another exist from the Lizard in Cornwall to the Brecklands of East Anglia to the northern isles of Scotland. This initial assessment suggests that the Endorsement Theory approach will provide the Environment Agency with a defensible, useable and useful tool. Uncertainties in the approach and areas requiring further research are identified. 4 An investigation into the best method to combine national and local data to develop site-specific critical loads CONTENTS 1.
Publisher: Environment Agency
Subject Keywords: Acidification; Vegetation; Soils; Critical loads; Designated sites; Endorsement theory
Extent: 63
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