Annual CO2 budget and seasonal CO2 exchange signals at a high Arctic permafrost site on Spitsbergen, Svalbard archipelago

[摘要] The annual variability of CO₂ exchange in most ecosystems is primarilydriven by the activities of plants and soil microorganisms. However, littleis known about the carbon balance and its controlling factors outside thegrowing season in Arctic regions dominated by soil freeze/thaw processes,long-lasting snow cover, and several months of darkness. This study presentsa complete annual cycle of the CO₂ net ecosystem exchange (NEE) dynamicsfor a high Arctic tundra area at the west coast of Svalbard based oneddy covariance flux measurements. The annual cumulative CO₂ budget isclose to 0 g C m⁻² yr⁻¹, but displays a strongseasonal variability. Four major CO₂ exchange seasons have beenidentified. (1) During summer (snow-free ground), the CO₂ exchangeoccurs mainly as a result of biological activity, with a dominance of strongCO₂ assimilation by the ecosystem. (2) The autumn (snow-free ground orpartly snow-covered) is dominated by CO₂ respiration as a result ofbiological activity. (3) In winter and spring (snow-covered ground), low butpersistent CO₂ release occurs, overlayed by considerable CO₂exchange events in both directions associated with high wind speed andchanges of air masses and atmospheric air pressure. (4) The snow melt season(pattern of snow-free and snow-covered areas) is associated with bothmeteorological and biological forcing, resulting in a carbon uptake by thehigh Arctic ecosystem. Data related to this article are archived at http://doi.pangaea.de/10.1594/PANGAEA.809507.

[学科分类] 地球化学与岩石