Federal Land Managers Critical Loads for Sulfur and Nitrogen Workshop March 30-April 1, 2004. Workshop Summary.

摘要

Aquatic and terrestrial ecosystems on federal lands are currently receiving deposition of atmospheric sulfur and nitrogen species. In some geographic areas, sensitive ecosystems are vulnerable to these atmospheric loads and are experiencing changes in ecosystem structure and function including acidification, fertilization, and eutrophication. During the late 1980s and 1990s, the European and Canadian communities developed procedures for estimating critical and target loads of atmospheric nitrogen and sulfur species that would protect vulnerable terrestrial/aquatic systems and permit the restoration of impaired systems. The application of the critical loading approach has been used by some Federal Land Managers (FLM) to estimate loading thresholds and limits of acceptable change for selected species (e.g., sugar maple, brook trout), or vulnerable processes (e.g., base cation exchange in granitic or non-karst geology watersheds). However, many features of the critical loads approach, such as selection of target biotic species or processes, selection of management endpoints, determination of critical versus target loads, and using this information in the decision making process, are not uniformly applied by FLMs. Greater consistency and comparability among FLMs would improve the critical load (CL) process.