CO 2 ‐fluxes in different plant communities of a high‐Arctic tundra watershed (Western Spitsbergen)

• Published in: Journal of Vegetation Science
• Main Authors: Wüthrich, Christoph, Möller, Ingo, Thannheiser, Dietbert
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1999
• Subjects: Plant Science; Ecology; Arctic; Tundra; Spitsbergen
• Online Access: http://dx.doi.org/10.2307/3237070; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F3237070; https://onlinelibrary.wiley.com/doi/pdf/10.2307/3237070

Abstract. There is little information on (1) whether the net carbon balance is positive or negative in different habitats in high Arctic ecosystems such as Spitsbergen today, and (2) what effect a cloudier, cooler summer could have on carbon balance. To provide data on this subject CO 2 ‐flux measurements in different plant communities were made in the high‐Arctic coastal tundra of Spitsbergen, using a mobile macro‐cuvette system based on infrared gas analysis. The study area was situated on the exposed west coast, where westerly winds produce precipitation daily in the form of rain, drizzle and fog. During the cold and cloudy measurement period in 1996, light and surface temperatures were limiting for primary producers, resulting in low size and low physiological activity of the plants. Net CO 2 ‐flux measurements showed carbon fluxes from soil to atmosphere in most of the communities even during the brightest hours of the day, when mean photon flux density was 325 mmol m ‐2 s ‐1 . Calculations based on spatial distribution of the plant communities and soils in the watershed combined with C‐flux measurements revealed information on daily carbon loss. For instance, the Drepanocladus community, covering 21 % of the catchment area, was responsible for 42.6 % of the catchment carbon loss. Only two of nine investigated plant communities, the Racomitrium and a Salix‐Saxifraga community on debris, both adapted to frequent fog situations, were able to compensate for respiratory CO 2 ‐losses under the prevailing low light conditions during daytime. Since there were no significant sunny periods in this area in the summer of 1996, the habitats of the investigated coastal tundra finished the season with a marked carbon loss due to increased cloudiness.