Abstract
To understand the implications of atmospheric nitrogen deposition on carbon turnover in peatlands, we conducted a C-13 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 C-13 pulse, and soil porewater DOC content under the two species. C-13 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 C-13 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. (C) 2010 Elsevier Ltd. All rights reserved.
Original language | English |
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Pages (from-to) | 495-502 |
Number of pages | 8 |
Journal | Soil Biology and Biochemistry |
Volume | 43 |
Issue number | 3 |
Early online date | 4 Dec 2010 |
DOIs | |
Publication status | Published - Mar 2011 |
Keywords
- pulse-chase labeling
- carbon allocation
- Eriophorum vaginatum
- Calluna vulgaris
- peat
- nitrogen deposition
- dissolved organic-carbon
- 2 upland perennials
- Pteridium-aquilinun
- soil respiration
- L hull
- mycorrhizal infection
- heathland vegetation
- nutrient limitation
- vascular plants
- climate-change