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

Use of satellite image classification to scale up the carbon stocks and fluxes in tundra ecosystems.

Virtanen, Tarmo^{*,1, 5}, Heikkinen, Juha^{*,2, 4}, Kuhry, Peter^*,3, Martikainen, Pertti^*,4, Mikkola, Kari^*,5, Nikula, Ari^*,5, ¹ Department of Biological and Environmental Sciences, Helsinki, Finland⁵ Rovaniemi Research Station, Rovaniemi, Finland² Employment and Economic Development Centre, Oulu, Finland⁴ Department of Environmental Sciences, Kuopio, Finland³ Department of Physical Geography and Quaternary Geology, Stockholm, Sweden

ABSTRACT- Global warming is a threat for the carbon reservoir in tundra ecosystems, as climatic conditions evidently impacts the carbon fluxes and stocks. The possibilities to develop and use satellite image based vegetation and land cover classifications in carbon flux and stock studies is a rapidly developing research area. We studied carbon dioxide exchange and methane dynamics of the various vegetation and land cover types in the Lek-Vorkuta catchment of the Usa Basin, Russia, and then calculated the gas balance and carbon stocks for the whole Usa Basin applying GIS techniques and using our own satellite image classification based vegetation and land cover classification. We also calculated the carbon fluxes for the entire East European tundra using more general classifications developed by other research groups. During a warm and dry summer our study area acted as a significant source for carbon. Only the wet peaty tundra acted as a sink for carbon, while the dryer soil surfaces were close to a zero carbon balance or lost carbon, as did the thermokarst lakes and rivers. Our data shows that dry tundra surfaces are the most sensitive for warming due to their high organic matter degradation capacity. Methane released from the wet peaty tundra, thermokarst lakes and rivers accounted for 29 % of the total global warming potential of emitted CO₂ and CH₄. The results show that the carbon balance in the East-European tundra is highly sensitive to climatic warming, and can have a positive feedback to global warming. Future improvements in the spatial resolution and more detailed class divisions of the present large area (continental or global) covering vegetation and land cover classifications would improve the precision of the flux and stock estimates based on the method we used.

Key words: Carbon fluxes, Carbon stocks, GIS