Net ecosystem methane and carbon dioxide exchanges in a Lake Erie coastal marsh and a nearby cropland. Issue 5 (2nd May 2014)

• Record Type: Journal Article
• Authors: Chu, Housen; Chen, Jiquan; Gottgens, Johan F.; Ouyang, Zutao; John, Ranjeet; Czajkowski, Kevin; Becker, Richard
• Is Part Of: Journal of geophysical research. Volume 119:Issue 5(2014)
• Page Start: 722
• Page End: 740
• Publication Date: 2014-05-02
• Subjects: Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2013JG002520
• Languages: English
• ISSNs: 2169-8953

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Net ecosystem carbon dioxide (F<sub>CO2</sub>) and methane (F<sub>CH4</sub>) exchanges were measured by using the eddy covariance method to quantify the atmospheric carbon budget at a <italic>Typha</italic>‐ and <italic>Nymphaea</italic>‐dominated freshwater marsh (March 2011 to March 2013) and a soybean cropland (May 2011 to May 2012) in northwestern Ohio, USA. Two year average annual F<sub>CH4</sub> (49.7 g C‐CH<sub>4</sub> m<sup>−2</sup> yr<sup>−1</sup>) from the marsh was high and compatible with its net annual CO<sub>2</sub> uptake (F<sub>CO2</sub>: −21.0 g C‐CO<sub>2</sub> m<sup>−2</sup> yr<sup>−1</sup>). In contrast, F<sub>CH4</sub> was small (2.3 g C‐CH<sub>4</sub> m<sup>−2</sup> yr<sup>−1</sup>) and accounted for a minor portion of the atmospheric carbon budget (F<sub>CO2</sub>: −151.8 g C‐CO<sub>2</sub> m<sup>−2</sup> yr<sup>−1</sup>) at the cropland. At the seasonal scale, soil temperature associated with methane (CH<sub>4</sub>) production provided the dominant regulator of F<sub>CH4</sub> at the marsh (<italic>R</italic><sup>2</sup> = 0.86). At the diurnal scale, plant‐modulated gas flow was the major pathway for CH<sub>4</sub> outgassing in the growing season at the marsh. Diffusion and ebullition became the major pathways in the nongrowing season and were regulated by friction velocity. Our findings highlight the importance of freshwater marshes for their efficiency in turning over and releasing newly fixed carbon as CH<sub>4</sub>. Despite marshes accounting for only ~4% of area in the agriculture‐dominated landscape, their high F<sub>CH4</sub> should be carefully addressed in the regional carbon budget.</p> </abstract>