Information Services banner Edinburgh Research Archive The University of Edinburgh crest

Edinburgh Research Archive >
Geosciences, School of >
Global Change Research Institute >
Global Change Research Institute PhD thesis collection >

Please use this identifier to cite or link to this item:

This item has been viewed 92 times in the last year. View Statistics

Files in This Item:

File Description SizeFormat
Kivimäki2011.doc26.66 MBMicrosoft Word
Kivimäki2011.pdf3.37 MBAdobe PDFView/Open
Title: Changes in carbon and nitrogen dynamics in Sphagnum capillifolium under enhanced nitrogen deposition
Authors: Kivimäki, Sanna Katariina
Supervisor(s): Sheppard, Lucy
Rees, Bob
Johnson, Sally
Grace, John
Issue Date: 24-Nov-2011
Publisher: The University of Edinburgh
Abstract: Peatland ecosystems only cover 2-3 % of the Earth‟s surface but they represent significant carbon stores, holding approximately one third of the global soil carbon (C). The major peat forming genera Sphagnum appears to be highly sensitive to increased N availability. Many studies have shown decreased productivity of Sphagnum which could lead to a decrease in the amount of C stored, especially as many studies also show an increase in the decomposition rate with higher N deposition. However, the overall effects of N on CO2 fluxes of Sphagnum remain unclear. The present study aimed to look at the effects of increased N on Sphagnum productivity, decomposition and CO2 fluxes after long-term N additions (> 5 years) using a field experiment at Whim Moss in southern Scotland where N deposition has been manipulated employing a very realistic application coupled to rainfall since 2002. The experiment also has treatments with PK addition to test the effects of removing P and/or K-limitation. Measurements of plant tissue nutrient concentrations, visual assessments of Sphagnum viability, and pore water analysis were also carried out. Nitrogen additions increased tissue N, and decreased Sphagnum shoot extension and productivity. Simultaneous P and K additions alleviated the effects of N on tissue N concentrations and growth, although this was only significant for shoot extension. Visual assessments correlated well with tissue chemistry and productivity; the decline in health was associated with high %N and reduced productivity. Interestingly, in the present study increased N decreased the mass loss and again when PK was added with N decomposition rates were more similar to the control. With respect to the carbon balance of the site and the sustainability of peatlands the results suggest that the negative effect of N on C assimilation may be partially offset by the reduced decomposition rates. The CO2 measurements showed a large loss of C as CO2 from all the Sphagnum plots which was exacerbated by adding N especially when the air temperature increased. The positive temperature response of ecosystem respiration with N additions suggests that in high N deposition areas climate change and subsequent temperature rises will increase C losses from bogs.
Sponsor(s): Scottish Natural Heritage
Keywords: peatland
nitrogen availability
carbon storage
Sphagnum productivity
carbon loss
Appears in Collections:Global Change Research Institute PhD thesis collection

Items in ERA are protected by copyright, with all rights reserved, unless otherwise indicated.


Valid XHTML 1.0! Unless explicitly stated otherwise, all material is copyright © The University of Edinburgh 2013, and/or the original authors. Privacy and Cookies Policy