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Title: Nonlinear CO 2 flux response to 7 years of experimentally induced permafrost thaw

Abstract

Rapid Arctic warming is expected to increase global greenhouse gas concentrations as permafrost thaw exposes immense stores of frozen carbon (C) to microbial decomposition. Permafrost thaw also stimulates plant growth, which could offset C loss. Using data from 7 years of experimental Air and Soil warming in moist acidic tundra, we show that Soil warming had a much stronger effect on CO 2 flux than Air warming. Soil warming caused rapid permafrost thaw and increased ecosystem respiration (R eco), gross primary productivity (GPP), and net summer CO 2 storage (NEE). Over 7 years R eco, GPP, and NEE also increased in Control (i.e., ambient plots), but this change could be explained by slow thaw in Control areas. In the initial stages of thaw, R eco, GPP, and NEE increased linearly with thaw across all treatments, despite different rates of thaw. As thaw in Soil warming continued to increase linearly, ground surface subsidence created saturated microsites and suppressed R eco, GPP, and NEE. However R eco and GPP remained high in areas with large Eriophorum vaginatum biomass. In general NEE increased with thaw, but was more strongly correlated with plant biomass than thaw, indicating that higher R eco in deeply thawedmore » areas during summer months was balanced by GPP. Summer CO 2 flux across treatments fit a single quadratic relationship that captured the functional response of CO 2 flux to thaw, water table depth, and plant biomass. These results demonstrate the importance of indirect thaw effects on CO 2 flux: plant growth and water table dynamics. Nonsummer R eco models estimated that the area was an annual CO 2 source during all years of observation. As a result, nonsummer CO 2 loss in warmer, more deeply thawed soils exceeded the increases in summer GPP, and thawed tundra was a net annual CO 2 source.« less

Authors:
ORCiD logo [1];  [2];  [1];  [2];  [3];  [1];  [4];  [1];  [2];  [1]
  1. Northern Arizona Univ., Flagstaff, AZ (United States)
  2. Univ. of Florida, Gainesville, FL (United States)
  3. Woods Hole Research Center, Falmouth, MA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1351785
Alternate Identifier(s):
OSTI ID: 1373823
Grant/Contract Number:  
AC05-00OR22725; SC0006982; SC0014085
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Global Change Biology
Additional Journal Information:
Journal Volume: 23; Journal Issue: 9; Journal ID: ISSN 1354-1013
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Arctic; carbon; ecosystem respiration; experimental warming; gross primary productivity; net ecosystem exchange; permafrost; thaw; tundra

Citation Formats

Mauritz, Marguerite, Bracho, Rosvel, Celis, Gerardo, Hutchings, Jack, Natali, Susan M., Pegoraro, Elaine, Salmon, Verity G., Schädel, Christina, Webb, Elizabeth E., and Schuur, Edward A. G. Nonlinear CO2 flux response to 7 years of experimentally induced permafrost thaw. United States: N. p., 2017. Web. doi:10.1111/gcb.13661.
Mauritz, Marguerite, Bracho, Rosvel, Celis, Gerardo, Hutchings, Jack, Natali, Susan M., Pegoraro, Elaine, Salmon, Verity G., Schädel, Christina, Webb, Elizabeth E., & Schuur, Edward A. G. Nonlinear CO2 flux response to 7 years of experimentally induced permafrost thaw. United States. doi:10.1111/gcb.13661.
Mauritz, Marguerite, Bracho, Rosvel, Celis, Gerardo, Hutchings, Jack, Natali, Susan M., Pegoraro, Elaine, Salmon, Verity G., Schädel, Christina, Webb, Elizabeth E., and Schuur, Edward A. G. Thu . "Nonlinear CO2 flux response to 7 years of experimentally induced permafrost thaw". United States. doi:10.1111/gcb.13661. https://www.osti.gov/servlets/purl/1351785.
@article{osti_1351785,
title = {Nonlinear CO2 flux response to 7 years of experimentally induced permafrost thaw},
author = {Mauritz, Marguerite and Bracho, Rosvel and Celis, Gerardo and Hutchings, Jack and Natali, Susan M. and Pegoraro, Elaine and Salmon, Verity G. and Schädel, Christina and Webb, Elizabeth E. and Schuur, Edward A. G.},
abstractNote = {Rapid Arctic warming is expected to increase global greenhouse gas concentrations as permafrost thaw exposes immense stores of frozen carbon (C) to microbial decomposition. Permafrost thaw also stimulates plant growth, which could offset C loss. Using data from 7 years of experimental Air and Soil warming in moist acidic tundra, we show that Soil warming had a much stronger effect on CO2 flux than Air warming. Soil warming caused rapid permafrost thaw and increased ecosystem respiration (Reco), gross primary productivity (GPP), and net summer CO2 storage (NEE). Over 7 years Reco, GPP, and NEE also increased in Control (i.e., ambient plots), but this change could be explained by slow thaw in Control areas. In the initial stages of thaw, Reco, GPP, and NEE increased linearly with thaw across all treatments, despite different rates of thaw. As thaw in Soil warming continued to increase linearly, ground surface subsidence created saturated microsites and suppressed Reco, GPP, and NEE. However Reco and GPP remained high in areas with large Eriophorum vaginatum biomass. In general NEE increased with thaw, but was more strongly correlated with plant biomass than thaw, indicating that higher Reco in deeply thawed areas during summer months was balanced by GPP. Summer CO2 flux across treatments fit a single quadratic relationship that captured the functional response of CO2 flux to thaw, water table depth, and plant biomass. These results demonstrate the importance of indirect thaw effects on CO2 flux: plant growth and water table dynamics. Nonsummer Reco models estimated that the area was an annual CO2 source during all years of observation. As a result, nonsummer CO2 loss in warmer, more deeply thawed soils exceeded the increases in summer GPP, and thawed tundra was a net annual CO2 source.},
doi = {10.1111/gcb.13661},
journal = {Global Change Biology},
number = 9,
volume = 23,
place = {United States},
year = {Thu Feb 16 00:00:00 EST 2017},
month = {Thu Feb 16 00:00:00 EST 2017}
}

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