Air‐water gas exchange by waving vegetation stems. Issue 7 (20th July 2016)

• Record Type: Journal Article
• Authors: Foster‐Martinez, M. R.; Variano, E. A.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 7(2016:Jul.)
• Page Start: 1916
• Page End: 1923
• Publication Date: 2016-07-20
• Subjects: emergent vegetation -- wetlands -- gas transfer velocity -- biogeochemcial modeling; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2016JG003366
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Exchange between wetland surface water and the atmosphere is driven by a variety of motions, ranging from rainfall impact to thermal convection and animal locomotion. Here we examine the effect of wind‐driven vegetation movement. Wind causes the stems of emergent vegetation to wave back and forth, stirring the water column and facilitating air‐water exchange. To understand the magnitude of this effect, a gas transfer velocity ( k 600 value) was measured via laboratory experiments. Vegetation waving was studied in isolation by mechanically forcing a model canopy to oscillate at a range of frequencies and amplitudes matching those found in the field. The results show that stirring due to vegetation waving produces k 600 values from 0.55 cm/h to 1.60 cm/h. The dependence of k 600 on waving amplitude and frequency are evident from the laboratory data. These results indicate that vegetation waving has a nonnegligible effect on gas transport; thus, it can contribute to a mechanistic understanding of the fluxes underpinning biogeochemical processes. Key Points: Emergent vegetation is a feature unique to wetlands that couples the atmosphere and water column Movement of emergent vegetation stirs the surface water and thereby facilitates air‐water gas exchange The accuracy of greenhouse gas budgets can be improved by adding this mechanism to the list of gas flux pathways