Temporal variability in plant and soil nitrogen pools in a high-Arctic ecosystem

Bardgett, Richard D.; van der Wal, Rene; Jónsdóttir, Ingibjörg S.; Quirk, Helen; Dutton, Stephen. 2007 Temporal variability in plant and soil nitrogen pools in a high-Arctic ecosystem. Soil Biology & Biochemistry, 39 (8). 2129-2137.

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This study determined temporal variability in N pools, both aboveground and belowground, across two contrasting plant communities in high-Arctic Spitsbergen, Svalbard (78°N). We measured N pools in plant material, soil microbial biomass and soil organic matter in moist (Alopecurus borealis dominated) and dry (Dryas octopetala dominated) meadow communities at four times during the growing season. We found that plant, microbial and dissolved inorganic and organic N pools were subject to significant, but surprisingly low, temporal variation that was controlled primarily by changes in temperature and moisture availability over the short growing season. This temporal variability is much less than that experienced in other seasonally cold ecosystems such as alpine tundra where strong seasonal partitioning of N occurs between plant and soil microbial pools. While only a small proportion of the total ecosystem N, the microbial biomass represented the single largest of the dynamic N pools in both moist and dry meadow communities (3.4% and 4.6% of the total ecosystem N pool, respectively). This points to the importance of soil microbial community dynamics for N cycling in high-Arctic ecosystems. Microbial N was strongly and positively related to soil temperature in the dry meadow, but this relationship did not hold true in the wet meadow where other factors such as wetter soil conditions might constrain biological activity. Vascular live belowground plant parts represented the single largest plant N pool in both dry and moist meadow, constituting an average of 1.6% of the total N pool in both systems; this value did not vary across the growing season or between plant communities. Overall, our data illustrate a surprisingly low growing season variability in labile N pools in high-Arctic ecosystems, which we propose is controlled primarily by temperature and moisture.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry
UKCEH and CEH Sections/Science Areas: Watt
ISSN: 0038-0717
Additional Keywords: high Arctic, nitrogen cycling, emporal variation, soil microbial biomass, nitrogen mineralisation, moss, dry and moist meadows
NORA Subject Terms: Agriculture and Soil Science
Biology and Microbiology
Ecology and Environment
Date made live: 23 Jan 2008 14:50 +0 (UTC)

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