Ecological effects of nitrogen deposition in the western United States

Mark E. Fenn, Jill S. Baron, Edith B. Allen, Heather M. Rueth, Koren R. Nydick, Linda Geiser, William D. Bowman, James O. Sickman, Thomas Meixner, Dale W. Johnson, Peter Neitlich

Research output: Contribution to journalReview articlepeer-review

538 Scopus citations


In the western United States vast acreages of land are exposed to low levels of atmospheric nitrogen (N) deposition, with interspersed hotspots of elevated N deposition downwind of large, expanding metropolitan centers or large agricultural operations. Biological response studies in western North America demonstrate that some aquatic and terrestrial plant and microbial communities are significantly altered by N deposition. Greater plant productivity is counterbalanced by biotic community changes and deleterious effects on sensitive organisms (lichens and phytoplankton) that respond to low inputs of N (3 to 8 kilograms N per hectare per year). Streamwater nitrate concentrations are elevated in high-elevation catchments in Colorado and are unusually high in southern California and in some chaparral catchments in the southwestern Sierra Nevada. Chronic N deposition in the West is implicated in increased fire frequency in some areas and habitat alteration for threatened species. Between hotspots, N deposition is too low to cause noticeable effects or has not been studied.

Original languageEnglish (US)
Pages (from-to)404-420
Number of pages17
Issue number4
StatePublished - Apr 1 2003


  • Biotic communities
  • Eutrophication
  • Lichens
  • Nitrogen saturation
  • Streamwater nitrate

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences


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