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The Influence of Abiotic Factors on Biological Nitrogen Fixation in Different Types of Vegetation in the High Arctic, Svalbard
Matthias Zielke, Anne Stine Ekker, Rolf A. Olsen, Sigmund Spjelkavik and Bjørn Solheim
Arctic, Antarctic, and Alpine Research
Vol. 34, No. 3 (Aug., 2002), pp. 293-299
Published by: INSTAAR, University of Colorado
Stable URL: http://www.jstor.org/stable/1552487
Page Count: 7
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The influence of environmental factors on the nitrogen fixation activity in soil and vegetation samples from different types of plant communities from the Sassen Valley (78°N, 16°E), Svalbard, Norway, was measured under controlled laboratory conditions using the acetylene reduction assay throughout the summers of 1997 and 2000. Samples for study were chosen from six sites along a 2-km-long transect representing different types of arctic vegetation. The influence of temperature, soil water content, and light intensity on acetylene reduction rates was studied. Samples from all sites showed low and almost constant acetylene reduction rates between 0 and 10°C. Above 10°C the activity of all samples increased rapidly and reached its maximum at about 25 and 32°C for the samples with free-living cyanobacteria and moss-associated cyanobacteria, respectively. There was a significant water-dependent increase of acetylene reduction activity for all types of vegetation. The samples showed a clear response to varying light conditions, i.e. a rapid decrease in acetylene reduction rates when light intensity decreased from 140 to 80 μmol m-2 s-1 depending on the type of vegetation.
Arctic, Antarctic, and Alpine Research © 2002 Regents of the University of Colorado, a body corporate, contracting on behalf of the University of Colorado at Boulder for the benefit of INSTAAR