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Annual and seasonal characteristics of CO 2 emission from five different ecosystems were studied in situ (Russia, Moscow Region) from November 1997 through October 2000. The annual behaviour of the soil respiration rate is influenced by weather conditions during a particular year. Annual CO 2 fluxes from the soils depend on land use of the soils and averaged 684 and 906 g C m −2 from sandy Albeluvisols (sod-podzolic soils) under forest and grassland, respectively. Annual emission from clay Phaeozems (grey forest soils) was lower and ranged from 422 to 660 g C m −2 ; the order of precedence was arable < grassland < forest. The coefficients of variation for annual CO 2 fluxes caused by weather conditions ranged from 18% (forest ecosystem on Phaeozems) to 31% (agroecosystem). The contribution from the cold period (with snow, November-April) to the annual CO 2 flux was substantial and averaged 21% and 14% for natural and agricultural ecosystems, respectively. The CO 2 fluxes comprised approximately 48-51% in summer, 23-24% in autumn, 18-20% in spring and 7-10% in winter of the total annual carbon dioxide flux.

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