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Nitrogen deposition does not enhance Sphagnum decomposition

Manninen, S.; Kivimaki, S.; Leith, I.D.; Leeson, S.R.; Sheppard, L.J.. 2016 Nitrogen deposition does not enhance Sphagnum decomposition. Science of the Total Environment, 571. 314-322. https://doi.org/10.1016/j.scitotenv.2016.07.152

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Abstract/Summary

Long-term additions of nitrogen (N) to peatlands have altered bryophyte growth, species dominance, N content in peat and peat water, and often resulted in enhanced Sphagnum decomposition rate. However, these results have mainly been derived from experiments in which N was applied as ammonium nitrate (NH4NO3), neglecting the fact that in polluted areas, wet deposition may be dominated either by NO3− or NH4+. We studied effects of elevated wet deposition of NO3− vs. NH4+ alone (8 or 56 kg N ha− 1 yr− 1 over and above the background of 8 kg N ha− 1 yr− 1 for 5 to 11 years) or combined with phosphorus (P) and potassium (K) on Sphagnum quality for decomposers, mass loss, and associated changes in hummock pore water in an ombrotrophic bog (Whim). Adding N, especially as NH4+, increased N concentration in Sphagnum, but did not enhance mass loss from Sphagnum. Mass loss seemed to depend mainly on moss species and climatic factors. Only high applications of N affected hummock pore water chemistry, which varied considerably over time. Overall, C and N cycling in this N treated bog appeared to be decoupled. We conclude that moss species, seasonal and annual variation in climatic factors, direct negative effects of N (NH4+ toxicity) on Sphagnum production, and indirect effects (increase in pH and changes in plant species dominance under elevated NO3− alone and with PK) drive Sphagnum decomposition and hummock C and N dynamics at Whim.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1016/j.scitotenv.2016.07.152
CEH Sections/Science Areas: CEH Fellows
Dise
ISSN: 0048-9697
Additional Keywords: ammonium, decomposition, nitrate, peatlands, hummock pore water, Sphagnum
NORA Subject Terms: Ecology and Environment
Agriculture and Soil Science
Date made live: 27 Sep 2016 15:48 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/514623

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