Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Nitrate Reductase Activity in Vegetation below an Arctic Bird Cliff, Svalbard, Norway

Ann Marie Odasz
Journal of Vegetation Science
Vol. 5, No. 6 (Dec., 1994), pp. 913-920
Published by: Wiley
Stable URL: http://www.jstor.org/stable/3236203
Page Count: 8
  • Download ($42.00)
  • Subscribe ($19.50)
  • Cite this Item
Nitrate Reductase Activity in Vegetation below an Arctic Bird Cliff, Svalbard, Norway
Preview not available

Abstract

Vegetated sites below bird-nesting cliffs are uniquely nutrient-rich habitats in the otherwise nutrient-poor arctic environment. Plants from six distinct vegetation zones below such a cliff at 79° N, Svalbard, Norway, were collected for analysis under greenhouse conditions. Leaf nitrate reductase activity (NRA) was analysed in 42 species representing 25 % of the Svalbard vascular flora. The species mean NRA values ranged from 0.37 to 8.34 μmols of nitrite ions formed per gram of plant fresh weight per hour. Species in the vegetated zone growing closest to recent guano deposits had the highest NRA values, (mean = 4.47) whereas plants growing farther below the cliff had significantly lower values (mean = 0.55). A similar pattern was detected in a duplicate set of plants induced with 15 mM KNO3 vegetation zone means for NRA ranged from 5.08 to 0.98 μmols of nitrite ions formed per gram of plant fresh weight per hour. Maximally induced species NRA values were highest in the first zones below the cliff and decreased downslope. This gradient paralleled the steep soil nitrate gradient, which decreased from 13.84 mg/l at the cliffbase to 1.03 mg/l downslope. Correspondingly, soil ammonium ions in the vegetation zones ranged between 1.96 mg/l at the cliff-base to 0.03 mg/l downslope. Correlations between NRA and soil nitrate provide a systematic basis for assigning scalar 'nitrogen figures' as indicators of habitat preference, here for the first time applied to arctic species.

Page Thumbnails

  • Thumbnail: Page 
913
    913
  • Thumbnail: Page 
914
    914
  • Thumbnail: Page 
915
    915
  • Thumbnail: Page 
916
    916
  • Thumbnail: Page 
917
    917
  • Thumbnail: Page 
918
    918
  • Thumbnail: Page 
919
    919
  • Thumbnail: Page 
920
    920