Atmospheric nitrogen deposition promotes carbon loss from peat bogs

L. Bragazza, C. Freeman, T. Jones, H. Rydin, J. Limpens, N. Fenner, T. Ellis, R. Gerdol, M. Hajek, T. Hajek, P. Iacumin, L. Kutnar, T. Tahvanainen, H. Toberman

Research output: Contribution to journalArticleAcademicpeer-review

348 Citations (Scopus)

Abstract

Peat bogs have historically represented exceptional carbon (C) sinks because of their extremely low decomposition rates and consequent accumulation of plant remnants as peat. Among the factors favoring that peat accumulation, a major role is played by the chemical quality of plant litter itself, which is poor in nutrients and characterized by polyphenols with a strong inhibitory effect on microbial breakdown. Because bogs receive their nutrient supply solely from atmospheric deposition, the global increase of atmospheric nitrogen (N) inputs as a consequence of human activities could potentially alter the litter chemistry with important, but still unknown, effects on their C balance. Here we present data showing the decomposition rates of recently formed litter peat samples collected in nine European countries under a natural gradient of atmospheric N deposition from ¿0.2 to 2 g·m-2.yr -1. We found that enhanced decomposition rates for material accumulated under higher atmospheric N supplies resulted in higher carbon dioxide (CO2) emissions and dissolved organic carbon release. The increased N availability favored microbial decomposition (i) by removing N constraints on microbial metabolism and (ii) through a chemical amelioration of litter peat quality with a positive feedback on microbial enzymatic activity. Although some uncertainty remains about whether decay-resistant Sphagnum will continue to dominate litter peat, our data indicate that, even without such changes, increased N deposition poses a serious risk to our valuable peatland C sinks
Original languageEnglish
Pages (from-to)19386-19389
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number51
DOIs
Publication statusPublished - 2006

Keywords

  • n-deposition
  • soil carbon
  • nutritional constraints
  • enzymatic-activity
  • ombrotrophic bogs
  • litter quality
  • organic-matter
  • climate-change
  • elevated co2
  • mass-loss

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