Carbon dioxide evolution from snow-covered agricultural ecosystems in Finland

Authors

• Hiroshi Koizumi Division of Plant Ecology, National Institute of Agro-Environmental Sciences, Tsukuba, Ibaraki, 305 Japan
• Markku Kontturi Agricultural Research Centre of Finland, Institute of Crop and Soil Science, FIN-31600 Jokioinen, Finland
• Shigeru Mariko Sugadaira Montane Research Center, University of Tsukuba, Sanada, Nagano, 386-22 Japan
• Timo Mela Agricultural Research Centre of Finland, Institute of Crop and Soil Science, FIN-31600 Jokioinen, Finland

DOI: https://doi.org/10.23986/afsci.72754

Abstract

The release of CO2 from the snow surface in winter and the soil surface in summer was directly or indirectly measured in three different soil types (peat, sand and clay) in agricultural ecosystems in Finland. The closed chamber (CC) method was used for the direct and Pick’s diffusion model (DM) method for the indirect measurements. The winter soil temperatures at 2-cm depth were between 0 and 1°C for each soil type. The concentration of CO2 within the snowpack increased linearly with snow depth. The average fluxes of CO2 calculated from the gradients of CO2 concentration in the snow using the DM method ranged from 10 to 27 mg CO2 m2h-1 and with the CC method from 18 to 27 mg CO2 m2h-1. These results suggest that the snow insulates the soil thermally, allowing CO2 production to continue at soil temperatures slightly above freezing in the winter. Carbon dioxide formed in the soil can move across the snowpack up to the atmosphere. The winter/summer ratio of CO2 evolution was estimated to exceed 4%. Therefore, the snow-covered crop soil served as a source of CO2 in winter, and CO2 evolution constitutes an important part of the annual CO2 budget in snowy regions.