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Title: Tundra is a consistent source of CO 2 at a site with progressive permafrost thaw during 6 years of chamber and eddy covariance measurements: Tundra CO 2 Fluxes

Current and future warming of high-latitude ecosystems will play an important role in climate change through feedbacks to the global carbon cycle. This study compares 6 years of CO 2 flux measurements in moist acidic tundra using autochambers and eddy covariance (Tower) approaches. Here, we found that the tundra was an annual source of CO 2 to the atmosphere as indicated by net ecosystem exchange using both methods with a combined mean of 105 ± 17 g CO 2 C m-2 y-1 across methods and years (Tower 87 ± 17 and Autochamber 123 ± 14). Furthermore, the difference between methods was largest early in the observation period, with Autochambers indicated a greater CO 2 source to the atmosphere. This discrepancy diminished through time, and in the final year the Autochambers measured a greater sink strength than tower. Active layer thickness was a significant driver of net ecosystem carbon exchange, gross ecosystem primary productivity, and Reco and could account for differences between Autochamber and Tower. The stronger source initially attributed lower summer season gross primary production (GPP) during the first 3 years, coupled with lower ecosystem respiration (Reco) during the first year. The combined suppression of GPP and Reco in themore » first year of Autochamber measurements could be the result of the experimental setup. Root damage associated with Autochamber soil collar installation may have lowered the plant community's capacity to fix C, but recovered within 3 years. And while this ecosystem was a consistent CO 2 sink during the summer, CO 2 emissions during the nonsummer months offset summer CO 2 uptake each year.« less
Authors:
ORCiD logo [1] ;  [2] ;  [3] ; ORCiD logo [4] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [5] ; ORCiD logo [2] ;  [3] ;  [1]
  1. Northern Arizona Univ., Flagstaff, AZ (United States); Univ. of Florida, Gainesville, FL (United States)
  2. Northern Arizona Univ., Flagstaff, AZ (United States)
  3. Univ. of Florida, Gainesville, FL (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Woods Hole Research Center, Falmouth, MA (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Biogeosciences
Additional Journal Information:
Journal Volume: 122; Journal Issue: 6; Journal ID: ISSN 2169-8953
Publisher:
American Geophysical Union
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES
OSTI Identifier:
1376643