The nitrogen fixation potential of arctic cryptogram species is influenced by enhanced UV-B radiation

Summary, in English

Abstract. Effects of enhanced UV-B (representing a 15% ozone depletion) on cyanobacterial nitrogen fixation were measured at a high arctic site (Adventdalen, 79°N, Svalbard) and a subarctic site (Abisko, 68°N, Sweden). Nitrogen fixation potential (acetylene reduction) by cyanobacteria associated with the moss Sanionia uncinata in vegetation exposed to experimentally enhanced levels of UV-B for 3 and 4 years in the high arctic in Adventdalen was reduced by 50% compared to controls after 3 years. No reduction in nitrogen fixation potential was observed in cyanobacteria associated with the moss Hylocomium splendens when previously exposed to enhanced UV-B in Abisko for a 7-year period. However, in the same experiment a 50% increase in summer precipitation stimulated nitrogen fixation potential by up to 6-fold above the natural precipitation treatments both in cyanobacteria associated with vegetation exposed to natural and enhanced UV-B radiation. In contrast to the lack of UV effect on moss-associated nitrogen fixation at the subarctic site, nitrogen fixation potential by the dominant lichen species Peltigera aphthosa was reduced by 50% when measured after 8 years exposure to elevated UV-B treatment. Evidence from these studies highlights the importance of UV-B radiation for cyanobacterial nitrogen fixation in the Arctic and future impact on nitrogen availability in such plant communities.

• Author: Bjørn Solheim; Ulf Johanson; Terry V. Callaghan; John A. Lee; Dylan Gwynn-Jones; Lars Olof Björn
• Department/s: Molecular Cell Biology
• Publishing year: 2002
• Language: English
• Pages: 90-93
• Publication/Series: Oecologia
• Volume: 133
• Issue: 1
• Links: http://dx.doi.org/10.1007/s00442-002-0963-z
• Document type: Journal article
• Publisher: Springer
• Topic: Biological Sciences
• Status: Published
• Project: Photobiology
• Research group: Photobiology
• ISBN/ISSN/Other: ISSN: 1432-1939