Fast assimilate turnover revealed by in situ ^sup 13^CO2 pulse-labelling in Subarctic tundra

• Published in: Polar biology Vol. 35; no. 8; p. 1209
• Main Authors: Subke, Jens-arne, Heinemeyer, Andreas, Vallack, Harry W, Leronni, Vincenzo, Baxter, Robert, Ineson, Phil
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.08.2012
• Subjects: Arctic zone; Carbon cycle; Carbon dioxide; Climate change; Foliage; Growing season; Leaves; Physiological responses; Plant communities; Plant ecology; Plant populations; Plant tissues; Taiga & tundra; Tundra; Vegetation
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-012-1167-6

Climatic changes in Arctic regions are likely to have significant impacts on vegetation composition and physiological responses of different plant types, with implications for the regional carbon (C) cycle. Here, we explore differences in allocation and turnover of assimilated C in two Subarctic tundra communities. We used an in situ ^sup 13^C pulse at mid-summer in Swedish Lapland to investigate C allocation and turnover in four contrasting tundra plant communities. We found a high rate of turnover of assimilated C in leaf tissues of Betula nana and graminoid vegetation at the height of the growing season, with a mean residence time of pulse-derived ^sup 13^C of 1.1 and 0.7 days, respectively. One week after the pulse, c. 20 and 15%, respectively, of assimilated label-C remained in leaf biomass, representing most likely allocation to structural biomass. For the perennial leaf tissue of the graminoid communities, a remainder of approximately 5% of the pulse-derived C was still traceable after 1 year, whereas none was detectable in Betula foliage. The results indicate a relatively fast C turnover and small belowground allocation during the active growing season of recent assimilates in graminoid communities, with comparatively slower turnover and greater investment in belowground allocation by B. nana vegetation.[PUBLICATION ABSTRACT]