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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Discussion papers
https://doi.org/10.5194/bg-2017-440
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2017-440
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 08 Nov 2017

Submitted as: research article | 08 Nov 2017

Review status
This discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The revised manuscript was not accepted.

Controls on spatial and temporal patterns of soil nitrogen availability in a High Arctic wetland

Jacqueline K. Y. Hung1, David M. Atkinson2, and Neal A. Scott1 Jacqueline K. Y. Hung et al.
  • 1Department of Geography and Planning, Queen's University, Kingston, K7N 3N6, Canada
  • 2Department of Geography and Environmental Studies, Ryerson University, Toronto, M5B 2K3, Canada

Abstract. Increased soil nutrient availability, and associated increase in vegetation productivity, could create a negative feedback between Arctic ecosystems and the climate system, reducing the contribution of Arctic ecosystems to future climate change. To predict whether this feedback will develop, it is important to understand the environmental controls over nutrient cycling in High Arctic ecosystems, and how they vary over space and time. This study explores the environmental controls over spatial patterns of soil nitrogen availability in a High Arctic wet sedge meadow and how they influence carbon exchange processes. Ion exchange resin membranes measured available inorganic nitrogen in soils throughout the growing season at a high spatial resolution, while environmental variables (e.g. active layer depth, soil temperature, soil moisture) and carbon flux measurements were taken at frequent intervals during the 2016 field season. Environmental measures correlated highly with total and late season nitrate levels (total season dry tracks nitrate R2 = 0.533, total season wet tracks nitrate R2 = 0.803, late season nitrate R2 = 0.622), with soil temperatures at 5 cm depth having the greatest effect. Soil available nitrate and ammonium correlated highly with total and early season gross primary productivity (total season wet tracks R2 = 0.685, early season dry tracks R2 = 0.788, early season wet tracks R2 = 0.785). Higher ammonium concentrations coincided with greater carbon dioxide uptake. Nitrate concentrations correlated strongly to soil moisture, but nitrate levels were much lower than ammonium concentrations, suggesting low rates of nitrification vs. mineralization. Similar patterns were observed regardless of whether the wet-sedge meadow was classified as wet or dry, but the relationships were always stronger in areas classified as wet, indicating the importance of moisture and water availability on abiotic processes in High Arctic wet sedge meadows. Topography played an important role in the movement and transport of water, which influenced how nutrients were cycled and moved within the wetland. Generally, the low-lying areas had the highest inorganic nitrogen concentrations. These results suggest that finer scale processes altering nitrogen availability may influence the overall carbon balance of wet sedge meadows in the High Arctic, and how these ecosystems may respond to changes in climate.

Jacqueline K. Y. Hung et al.
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AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Jacqueline K. Y. Hung et al.
Jacqueline K. Y. Hung et al.
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Short summary
This paper presents findings that highlight the intricate relationships that exist between plant-available nutrients and carbon exchange in a High Arctic environment. The findings here suggest that finer scale processes altering nitrogen availability have influence on the overall carbon balance of wet sedge meadows in the High Arctic. Seasonal changes in nutrient availability is one key factor that regulates the magnitude and direction of responses to climate change.
This paper presents findings that highlight the intricate relationships that exist between...
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