Abstract

The contemporary role of mires in carbon exchange with the atmosphere is intensely debated. Thus, understanding the variation in Holocene peat accumulation is particularly important. We investigated carbon (C) and nitrogen (N) accumulation rates and their potential controls during the Holocene at the oligotrophic fen Degero Stormyr (64 degrees 11N, 19 degrees 33E, 270 m a.s.l.), Sweden. The peat stratigraphy was dominated by remains of Eriophorum spp. and oligotrophic-mesotrophic Sphagnum spp. The long-term rate of C accumulation (LORCA) was 13.7 +/- 5.5 (SD) g C m(-2) yr(-1), while the long-term rate of N accumulation (LORNA) was 0.28 +/- 0.14 (SD) g N m(-2) yr(-1). Carbon and N accumulation rates exhibited similar variations that coincided with major changes in botanical composition. The botanical composition of the peat also had a major impact on the percentage of amorphous peat (a proxy for degree of decomposition). Bulk C-13 values increased with decreasing C content, which probably reflected the relative increase of C-13 depleted compounds in the peat during decomposition. Different plant groups exhibited different relationships, likely due to different C-13 signatures of initial litters from Eriophorum spp. and Sphagnum spp. The N-15 values increased significantly with decreasing C:N ratio in bulk peat, likely reflecting preferential uptake of N-14 by plants concomitant with nitrogen mineralization. Here, we demonstrate the importance of botanical composition in affecting C and N accumulation rates under a changing climate and suggest that primary production drives the variation in rates of accumulation. Furthermore, we point out the importance of including C-13 and N-15 signatures in the analysis of peat stratigraphies to advance interpretation of Holocene peat growth and decay.

Keywords

C-13; N-15; carbon accumulation; decomposition; Holocene; nitrogen accumulation; oligotrophic fen; Sweden

Published in

Holocene
2017, Volume: 27, number: 6, pages: 811-821

SLU Authors

• Larsson, Anna

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Segerström, Ulf

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Nilsson, Mats

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1177/0959683616675936

Permanent link to this page (URI)

https://res.slu.se/id/publ/80150