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The Nitrogen Balance of Arctic Tundra: Pathways, Rates, and Environmental Implications¹

ABSTRACT

The magnitude of the inputs and exports of nitrogen was estimated for the tundra ecosystem at Barrow, Alaska. Based on new data and on previous investigations, annual input of nitrogen from all sources was 92.4 mg N/m² per year, with the most important sources being nitrogen fixation (75%) and ammonia in summer rain (18%). The low input of nitrogen by rain and snow results from both low annual precipitation and extremely low concentrations of nitrogen compounds in precipitation. Despite the meager nitrogen supply, the estimated retention is over 80% of the input, reflecting insignificant leaching due to the impermeable permafrost substrate, low precipitation, and restricted lateral movement of water over and through the nonfrozen soils. Denitrification also is low, at least partially due to nutrient deficiency.

Interpretations of these data in respect to the sensitivity of the environment to perturbations, suggest that resource development or other activities which would have minor or negligible effects in temperate latitudes, could alter substantially the nitrogen balance of this arctic ecosystem.

Key Words: denitrification • nutrient deficiency • geochemical balance

¹ Contribution Number 221 from the Institute of Marine Science, University of Alaska, Fairbanks, Alaska 99701. This research was supported by NSF Grant GV29342 from the International Biological Program and the Office of Polar Programs as an activity of the U. S. Tundra Biome. Field and laboratory support at Barrow, Alaska, was provided by the Naval Arctic Research Laboratory of the Office of Naval Research.

² Professors of Marine Science, Univ. of Alaska.

Received for publication February 20, 1974.