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Five years of simulated atmospheric nitrogen deposition have only subtle effects on the fate of newly synthesized carbon in Calluna vulgaris and Eriophorum vaginatum

Currey, Pauline M.; Johnson, David; Dawson, Lorna A.; van der Wal, Rene; Thornton, Barry; Sheppard, Lucy J.; Leith, Ian D.; Artz, Rebekka R.E.. 2011 Five years of simulated atmospheric nitrogen deposition have only subtle effects on the fate of newly synthesized carbon in Calluna vulgaris and Eriophorum vaginatum. Soil Biology and Biochemistry, 43 (3). 495-502. 10.1016/j.soilbio.2010.11.003

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Abstract/Summary

To understand the implications of atmospheric nitrogen deposition on carbon turnover in peatlands, we conducted a 13C pulse labeling experiment on Calluna vulgaris and Eriophorum vaginatum already receiving long-term (5 years) amendments of 56 kg N ha−1 y−1 as ammonium or nitrate. We examined shoot tissue retention, net ecosystem respiration returns of the 13C pulse, and soil porewater DOC content under the two species. 13C fixation in Eriophorum leaves was enhanced with nitrogen addition and doubled with nitrate supply. This newly fixed C appeared to be relocated below-ground faster with nitrogen fertilization as respiration returns were unaffected by N inputs. By contrast, increases in 13C fixation were not observed in Calluna. Instead, net ecosystem respiration rates over Calluna increased with N fertilization. There was no significant label incorporation into DOC, suggesting a conservative strategy of peatland vegetation regarding allocation of C through root exudation. Greater concentrations of total DOC were identified with nitrate addition in Calluna. Given the long-term nature of the experiment and the high N inputs, the overall impacts of nitrogen amendments on the fate of recently synthesized C in Eriophorum and Calluna in this ombrotrophic peatland were surprisingly more moderate than originally hypothesized. This may be due to N being effectively retained within the bryophyte layer, thus limiting, and delaying the onset of, below-ground effects.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.soilbio.2010.11.003
Programmes: CEH Topics & Objectives 2009 onwards > Biogeochemistry
CEH Sections: Billett (to 30 Nov 2013)
ISSN: 0038-0717
Additional Keywords: pulse-chase labeling, carbon allocation, Eriophorum vaginatum, Calluna vulgaris, peat, nitrogen deposition
NORA Subject Terms: Botany
Ecology and Environment
Date made live: 31 Aug 2011 14:19
URI: http://nora.nerc.ac.uk/id/eprint/14998

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