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Title
How is nitrogen fixation in the high arctic linked to greenhouse gas emissions?
Fields of Research (FoR) 2008:
Author(s)
Publication Date
2013
Socio-Economic Objective (SEO) 2008
Early Online Version
Abstract
<i>Background and aims</i> Approximately 50 % of belowground organic carbon is present in the northern permafrost region and due to changes in climate there are concerns that this carbon will be rapidly released to the atmosphere. The release of carbon in arctic soils is thought to be intimately linked to the N cycle through the N cycle’s influence on microbial activity. The majority of new N input into arctic systems occurs through N<sub>2</sub>-fixation; therefore, N<sub>2</sub>-fixation may be the key driver of greenhouse gases from these ecosystems.<br/><i>Methods</i> At Alexandra Fjord lowland, Ellesmere Island, Canada concurrent measurements of N<sub>2</sub>-fixation, N mineralization and nitrification rates, dissolved organic soil N (DON) and C, inorganic soil N and surface greenhouse gas fluxes (CO<sub>2</sub>, N<sub>2</sub>O and CH<sub>4</sub>) were taken in two ecosystem types (Wet Sedge Meadow and Dryas Heath) over the 2009 growing season (June-August). Using Structural Equation Modelling we evaluated the hypothesis that CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O flux are linked to N<sub>2</sub>-fixation via the N cycle.<br/><i>Results</i> The soil N cycle was linked to CO<sub>2</sub> flux in the Dryas Heath ecosystem via DON concentrations, but there was no link between the soil N cycle and CO<sub>2</sub> flux in the Wet Sedge Meadow. Methane flux was also not linked to the soil N cycle, nor surface soil temperature or moisture in either ecosystem. The soil N cycle was closely linked to N<sub>2</sub>O emissions but via nitrification in the Wet Sedge Meadow and inorganic N in the Dryas Heath, indicating the important role of nitrification in net N<sub>2</sub>O flux from arctic ecosystems.<br/><i>Conclusions</i> Our results should be interpreted with caution given the high variability in both the rates of the N cycling processes and greenhouse gas flux found in both ecosystems over the growing season. However, while N<sub>2</sub>-fixation and other N cycling processes may play a more limited role in instantaneous CO<sub>2</sub> emissions, these processes clearly play an important role in controlling N<sub>2</sub>O emissions.
Publication Type
Journal Article
Source of Publication
Plant and Soil, 362(1-2), p. 215-229
Publisher
Springer Netherlands
Socio-Economic Objective (SEO) 2020
2012-05-16
Place of Publication
Netherlands
ISSN
1573-5036
0032-079X
Fields of Research (FoR) 2020
Socio-Economic Objective (SEO) 2020
Peer Reviewed
Yes
HERDC Category Description
Peer Reviewed
Yes
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