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
Cross-scale feedbacks in peatland development and carbon cycling.
Belyea, Lisa*,1, Baird, Andrew2, 1 University of Edinburgh, Edinburgh, UK2 Queen Mary, University of London, London, UK
ABSTRACT- Stage of ecosystem development is one of the primary controls on peatland carbon (C) cycling. Rate of C sequestration declines as a peat deposit grows, and methane emission increases as wet microhabitats expand in area. We examine the theoretical basis, underlying assumptions and empirical evidence for two highly influential models of peatland development: Clymo's (1984) peat accumulation model and Ingram's (1982) groundwater mound hypothesis. The principal limitations of these models are that they ignore fast processes occurring near the peatland surface, as well as interactions between peat accumulation and hydrology. As a result, they are unable to predict the effects of climate forcing on peatland C sequestration or developmental changes in the spatial distribution of wet and dry microhabitats (and hence methane emission). We present a hierarchical, complex systems approach to modelling peatland development, in which feedback occurs between peat growth and hydrological functioning at a range of temporal and spatial scales. The most rapidly changing parts of a peatland are localised in a vertical direction (i.e., height of the water table or free water surface relative to the peatland surface) and in a horizontal direction (i.e., boundaries between wet and dry microhabitats). Cross-scale feedbacks are captured by disaggregating the system, both vertically and horizontally, into a set of components that interact with each other. Both internal dynamics and external forcing drive changes in water table position and microhabitat pattern. These autogenic and allogenic changes in peatland structure affect hydrological processes which, in turn, constrain peatland development and carbon cycling.
Key words: peatlands, carbon cycle, ecosystem development, hydrology