Seabird-affected taluses are denitrification hotspots and potential N2O emitters in the High Arctic

In High Arctic tundra ecosystems, seabird colonies create nitrogen cycling hotspots because of bird-derived labile organic matter. However, knowledge about the nitrogen cycle in such ornithocoprophilous tundra is limited. Here, we determined denitrification potentials and in-situ nitrous oxide (N 2...

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Published in:Scientific reports 2018-11, Vol.8 (1), p.1-11, Article 17261
Main Authors: Hayashi, Kentaro, Tanabe, Yukiko, Ono, Keisuke, Loonen, Maarten J. J. E., Asano, Maki, Fujitani, Hirotsugu, Tokida, Takeshi, Uchida, Masaki, Hayatsu, Masahito
Format: Article
Language:English
Subjects:
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Air temperature
Aquatic birds
Denitrification
Emissions
Humanities and Social Sciences
multidisciplinary
Nitrification
Nitrogen
Nitrogen cycle
Nitrous oxide
Organic matter
Science
Science (multidisciplinary)
Soil surfaces
Soil temperature
Soils
Tundra
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Summary:In High Arctic tundra ecosystems, seabird colonies create nitrogen cycling hotspots because of bird-derived labile organic matter. However, knowledge about the nitrogen cycle in such ornithocoprophilous tundra is limited. Here, we determined denitrification potentials and in-situ nitrous oxide (N 2 O) emissions of surface soils on plant-covered taluses under piscivorous seabird cliffs at two sites (BL and ST) near Ny-Ålesund, Svalbard, in the European High Arctic. Talus soils at both locations had very high denitrification potentials at 10 °C (2.62–4.88 mg N kg −1 dry soil h −1 ), near the mean daily maximum air temperature in July in Ny-Ålesund, with positive temperature responses at 20 °C (Q10 values, 1.6–2.3). The talus soils contained abundant denitrification genes, suggesting that they are denitrification hotspots. However, high in-situ N 2 O emissions, indicating the presence of both active aerobic nitrification and anaerobic denitrification, were observed only at BL (max. 16.6 µg N m −2 h −1 ). Rapid nitrogen turnover at BL was supported by lower carbon-to-nitrogen ratios, higher nitrate content, and higher δ 15 N values in the soils at BL compared with those at ST. These are attributed to the 30-fold larger seabird density at BL than at ST, providing the larger organic matter input.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-35669-w