Multiple levels of nitrogen applied to an oligohaline marsh identify a plant community response sequence to eutrophication

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 417:73-82 (2010) - DOI: https://doi.org/10.3354/meps08808 Multiple levels of nitrogen applied to an oligohaline marsh identify a plant community response sequence to eutrophication Sean A. Graham*, Irving A. Mendelssohn Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, Energy, Coast & Environment Building, Baton Rouge, Louisiana 70803, USA *Email: sgraham@lsu.edu ABSTRACT: We enriched experimental plots in a Sagittaria lancifolia L. dominated oligohaline marsh for 4 yr with one of 4 levels of nitrogen (N) (0, 50, 200, or 1200 kg N ha–1 yr–1) in combination with one of 2 levels of phosphorus (P) (0 or 131 kg P ha–1 yr–1) to investigate nutrient limitation of primary production and plant community- and species-level responses to nutrient enrichment. Overall, significant changes in ecosystem structure and function occurred with N enrichment only; P enrichment had no significant effect alone or in interaction with N. Both 200 and 1200 kg N ha–1 yr–1 stimulated above-ground plant production. Enrichment with 1200 kg N ha–1 yr–1 also increased S. lancifolia tissue N:P ratio, reduced S. lancifolia N and P resorption during senescence, and altered the relative dominance of the 3 dominant species, but had no effect on species richness. We conclude that (1) N limits above-ground primary production in this oligohaline marsh; (2) the plant response to N enrichment is sequential: moderate N loading stimulated plant production only, while high N loading maintained the elevated production and also altered plant tissue nutrients and species dominance, but not species richness; (3) N enrichment beyond the assimilation capacity of the vegetation drives changes in ecosystem structure caused by altered plant nutrient cycling; and (4) linear changes in species dominance with increasing N enrichment suggest that further nutrient enrichment in time or quantity may result in a shift in species dominance and reduced species richness. KEY WORDS: Marsh · Nutrient enrichment · Nitrogen limitation · Primary production · Relative dominance · Nutrient resorption · Louisiana Full text in pdf format PreviousNextCite this article as: Graham SA, Mendelssohn IA (2010) Multiple levels of nitrogen applied to an oligohaline marsh identify a plant community response sequence to eutrophication. Mar Ecol Prog Ser 417:73-82. https://doi.org/10.3354/meps08808 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 417. Online publication date: November 04, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.