HR: 0800h
AN: B11A-0998    [Abstracts]
TI: Isotopic Signature of Carbon Dioxide Efflux as Affected by Vegetation Recovery in Peatland.
AU: * Epron, D
EM: daniel.epron@scbiol.uhp-nancy.fr
AF: University Henri Poincare, UMR INRA UHP 1137 Faculty ofSciences BP 239, Vandoeuvre, 54506 France
AU: Bortoluzzi, E
EM: estelle.bortoluzzi@univ-fcomte.fr
AF: University of Franche Comte, UMR CNRS UFC 6565 Faculty of Sciences La Bouloie, Besancon, 25030 France
AU: Buttler, A
EM: alexandre.buttler@epfl.ch
AF: Swiss Federal Institute of Technology-EPFL, Laboratoire des Systemes ecologiques PB 96, Lausanne, 1015 Switzerland
AB: Peatlands are widespread ecosystems in all climatic areas of the world and provide services of global significance such as long-term storage of organic carbon. The rehabilitation of degraded peatlands as a carbon sink is a considerable challenge in the context of climate change and issues such as capability of ecosystems for carbon sequestration and mitigating greenhouse gas emissions. Our aim was to study the isotopic composition of peatland CO₂ efflux at various stages of development of mire vegetation and new peat accumulation on the top of the old drained peat, in order to quantify the contribution of vegetation respiration to the whole CO₂ efflux of the ecosystem. The study site is located in the Jura mountains at the altitude of 870m and belongs to the European project RECIPE (reconciling commercial exploitation of peat with biodiversity in peatland ecosystems). It exhibited various regeneration stages with patches of bare peat, patches recently recolonised with cottongrass ( Eriophorum angustifolium) and areas covered with a deep layer of Sphagnum plants and litter (advanced regeneration). Keeling plots were realized on collars located in various vegetation patches by accumulating respired CO₂ into a dark chamber. δ¹³C of the respired CO₂ was measured using a mass-spectrometer. The isotopic signature of respired CO₂ was lower in the advanced regeneration than it was in recent regeneration, and the latter was lower than it was on bare peat. This difference agrees with the higher δ¹³C of the old peat than of the actual vegetation (both vascular plants and mosses, and their litters), suggesting a decreasing contribution of old peat mineralization to ecosystem CO₂ efflux with the progression of the regeneration of the cutover bog. Discrepancies between isotopic compositions of bulk organic matter and respired CO₂ suggest an apparent discrimination during respiration.
DE: 0428 Carbon cycling (4806)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0481 Restoration
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: Fall Meeting 2005