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The Importance of Lake Emergent Aquatic Vegetation for Estimating Arctic-Boreal Methane Emissions
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  • Ethan Kyzivat,
  • Laurence Smith,
  • Fenix Garcia Tigeros,
  • Chang Huang,
  • Chao Wang,
  • Theodore Langhorst,
  • Jessica V Fayne,
  • Merritt Harlan,
  • Yuta Ishitsuka,
  • Dongmei Feng,
  • Wayana Dolan,
  • Lincoln H Pitcher,
  • Tamlin M Pavelsky,
  • David Butman,
  • Kimberly P Wickland,
  • Mark M Dornblaser,
  • Robert Striegl,
  • Colin Joseph Gleason
Ethan Kyzivat
Brown University, Brown University, Brown University

Corresponding Author:[email protected]

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Laurence Smith
Brown University, Brown University, Brown University
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Fenix Garcia Tigeros
University of Washington, University of Washington, University of Washington
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Chang Huang
Northwest Unversity, Northwest Unversity, Northwest Unversity
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Chao Wang
University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill
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Theodore Langhorst
University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill
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Jessica V Fayne
University of California, University of California, University of California
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Merritt Harlan
University of Massachusetts Amherst, University of Massachusetts Amherst, University of Massachusetts Amherst
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Yuta Ishitsuka
Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Department of Civil and Environmental Engineering, University of Massachusetts Amherst
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Dongmei Feng
University of Massachusetts Amherst, University of Massachusetts Amherst, University of Massachusetts Amherst
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Wayana Dolan
University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill
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Lincoln H Pitcher
University of Colorado Boulder, University of Colorado Boulder, University of Colorado Boulder
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Tamlin M Pavelsky
University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill
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David Butman
University of Washington, University of Washington, University of Washington
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Kimberly P Wickland
United States Geological Survey, United States Geological Survey, United States Geological Survey
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Mark M Dornblaser
United States Geological Survey, United States Geological Survey, United States Geological Survey
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Robert Striegl
United States Geological Survey, United States Geological Survey, United States Geological Survey
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Colin Joseph Gleason
University of Massachusetts Amherst, University of Massachusetts Amherst, University of Massachusetts Amherst
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Abstract

Areas of lakes that support emergent aquatic vegetation emit disproportionately more methane than open water but are under-represented in upscaled estimates of lake greenhouse gas emissions. These shallow areas are typically less than ~1.5 m deep and can be estimated through synthetic aperture radar (SAR) mapping. To assess the importance of lake emergent vegetation (LEV) zones to landscape-scale methane emissions, we combine airborne SAR mapping with field measurements of vegetated and open-water methane flux. First, we use Uninhabited Aerial Vehicle SAR (UAVSAR) data from the NASA Arctic-Boreal Vulnerability Experiment (ABoVE) to map LEV in 4,572 lakes across four Arctic-boreal study areas and find it comprises ~16% of lake area, exceeding previous estimates, and exhibiting strong regional differences (averaging 59 [50–68]%, 22 [20-25]%, 1.0 [0.8-1.2]%, and 7.0 [5.0-12]% of lake areas in the Peace-Athabasca Delta, Yukon Flats, and northern and southern Canadian Shield, respectively). Next, we account for these vegetated areas through a simple upscaling exercise using paired methane fluxes from regions of open water and LEV. After excluding vegetated areas that could be accounted for as wetlands, we find that inclusion of LEV increases overall lake emissions by 21 [18-25]% relative to estimates that do not differentiate lake zones. While LEV zones are proportionately greater in small lakes, this relationship is weak and varies regionally, underscoring the need for methane-relevant remote sensing measurements of lake zones and a consistent criterion for distinguishing wetlands. Finally, Arctic-boreal lake methane upscaling estimates can be improved with more measurements from all lake zones.
Jun 2022Published in Journal of Geophysical Research: Biogeosciences volume 127 issue 6. 10.1029/2021JG006635