PARENT SESSION
Organized Oral Session 13: Gas exchange and global change in peatlands: From soil to satellite
Organizer(s): J Limpens, G Schaepman, MB Nilsson, and MM Heijmans
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 510b, Level 5, Palais des congrès de Montréal

Biogeochemical controls on CO₂ and CH₄ fluxes in peatlands: From intracellular symbionts to plant-environment interactions.

Lamers, Leon^{1, 2}, Smolders, Alfons², Tomassen, Hilde², Roelofs, Jan^{1, 2}, ¹ Environmental Biology, Institute for Wetland and Water Research, Radboud University Nijmegen, Nijmegen, the Netherlands² Research Centre B-Ware, Nijmegen, the Netherlands

ABSTRACT- The direction and rates of fluxes of CO₂ and CH₄ between peatlands (bogs, fens, marshes) and the atmosphere are determined by the rates of microbial and chemical production, CO₂ fixation by biomass production, CH₄ consumption, and gas ebullition or diffusion. The flux regulation even includes small-scale phenomena like the recently discovered intracellular methanotrophic symbionts providing C for photosynthesis in Sphagnum, and reducing CH₄ losses to the atmosphere. A wide range of physicochemical variables including temperature, humidity, pO₂ , peat structure, alkalinity, pH, SO₄^2-, NH₄⁺, NO₃^-, HPO₄^2- strongly interfere with CO₂ and CH₄ biogeochemistry. This holds for both pristine peatlands and for those disturbed by desiccation, global warming, and pollution (S, N, P). Fluxes of CO₂ and CH₄ are also indirectly influenced by changes in vegetation composition as a result of the biogeochemical changes mentioned above. These changes may significantly change decomposition rates (peat quality), C sequestration (biomass production), and physical pathways for both gases (funnel effect). The present paper will bring together these biogeochemical and biological controls on the fluxes of CO₂ and CH₄ into a conceptual model, and attempt to indicate the implications found at this peat soil scale for our understanding at higher scales (up to remote sensing by satellites).

Key words: carbon fluxes, carbon dioxide, methane, peatlands