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Book chapter
Effects and Empirical Critical Loads of Nitrogen for Ecoregions of the United States
Critical Loads and Dynamic Risk Assessments, pp.129-169
Environmental Pollution Series, Springer Nature
01/01/2015
Web of Science ID: WOS:000365670800006
Abstract
Human activity in the last century has increased nitrogen (N) deposition to a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. We synthesized current research relating atmospheric N deposition to effects on terrestrial and freshwater ecosystems in the United States, and estimated associated empirical critical loads of N for several receptors: freshwater diatoms, mycorrhizal fungi, lichens, bryophytes, herbaceous plants, shrubs, and trees. Biogeochemical responses included increased N mineralization and nitrification, increased gaseous N losses, and increased N leaching. Individual species, population, and community responses included increased tissue N, physiological and nutrient imbalances, increased growth, altered root-shoot ratios, increased susceptibility to secondary stresses, altered fire regime, shifts in competitive interactions and community composition, changes in species richness and other measures of biodiversity, and increases in invasive species. The range of critical loads of nutrient N reported for U.S. ecoregions, inland surface waters, and freshwater wetlands is 1–39 kg N ha−1 yr−1, spanning the range of N deposition observed over most of the country. The empirical critical loads of N tend to increase in the following sequence: diatoms, lichens and bryophytes, mycorrhizal fungi, herbaceous plants and shrubs, trees.
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Details
- Title
- Effects and Empirical Critical Loads of Nitrogen for Ecoregions of the United States
- Publication Details
- Critical Loads and Dynamic Risk Assessments, pp.129-169
- Resource Type
- Book chapter
- Contributors
- W DeVries (Editor)J P Hettelingh (Editor)M Posch (Editor)
- Publisher
- Springer Nature; Dordrecht
- Series
- Environmental Pollution Series
- Number of pages
- 41
- Copyright
- © 2015 Springer Science+Business Media Dordrecht
- Identifiers
- WOS:000365670800006; 99380171951606600
- Academic Unit
- Hal Marcus College of Science and Engineering ; Biology
- Language
- English