Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence
Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH4), a potent greenhouse gas. To examine the effects...
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ftuninhampshire:oai:scholars.unh.edu:faculty_pubs-1401 2023-05-15T17:56:50+02:00 Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence Johnston, Carmel E. Ewing, Stephanie A. Harden, Jennifer W. Varner, Ruth K. Wickland, Kimberly P. Koch, Joshua C. Fuller, Christopher C. Manies, Kristen Jorgenson, M. Torre 2014-08-26T07:00:00Z application/pdf https://scholars.unh.edu/faculty_pubs/402 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1401&context=faculty_pubs unknown University of New Hampshire Scholars' Repository https://scholars.unh.edu/faculty_pubs/402 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1401&context=faculty_pubs © 2014 IOP Publishing Ltd. Faculty Publications text 2014 ftuninhampshire 2023-01-30T21:49:54Z Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH4), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO2) and CH4 exchange along sites that constitute a ~1000 yr thaw chronosequence of thermokarst collapse bogs and adjacent fen locations at Innoko Flats Wildlife Refuge in western Alaska. Peak CH4 exchange in July (123 ± 71 mg CH4–C m−2 d−1) was observed in features that have been thawed for 30 to 70 (<100) yr, where soils were warmer than at more recently thawed sites (14 to 21 yr; emitting 1.37 ± 0.67 mg CH4–C m−2 d−1 in July) and had shallower water tables than at older sites (200 to 1400 yr; emitting 6.55 ± 2.23 mg CH4–C m−2 d−1 in July). Carbon lost via CH4 efflux during the growing season at these intermediate age sites was 8% of uptake by net ecosystem exchange. Our results provide evidence that CH4 emissions following lowland permafrost thaw are enhanced over decadal time scales, but limited over millennia. Over larger spatial scales, adjacent fen systems may contribute sustained CH4 emission, CO2 uptake, and DOC export. We argue that over timescales of decades to centuries, thaw features in high-latitude lowland peatlands, particularly those developed on poorly drained mineral substrates, are a key locus of elevated CH4 emission to the atmosphere that must be considered for a complete understanding of high latitude CH4 dynamics. Text permafrost Thermokarst Alaska University of New Hampshire: Scholars Repository |
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University of New Hampshire: Scholars Repository |
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description |
Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH4), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO2) and CH4 exchange along sites that constitute a ~1000 yr thaw chronosequence of thermokarst collapse bogs and adjacent fen locations at Innoko Flats Wildlife Refuge in western Alaska. Peak CH4 exchange in July (123 ± 71 mg CH4–C m−2 d−1) was observed in features that have been thawed for 30 to 70 (<100) yr, where soils were warmer than at more recently thawed sites (14 to 21 yr; emitting 1.37 ± 0.67 mg CH4–C m−2 d−1 in July) and had shallower water tables than at older sites (200 to 1400 yr; emitting 6.55 ± 2.23 mg CH4–C m−2 d−1 in July). Carbon lost via CH4 efflux during the growing season at these intermediate age sites was 8% of uptake by net ecosystem exchange. Our results provide evidence that CH4 emissions following lowland permafrost thaw are enhanced over decadal time scales, but limited over millennia. Over larger spatial scales, adjacent fen systems may contribute sustained CH4 emission, CO2 uptake, and DOC export. We argue that over timescales of decades to centuries, thaw features in high-latitude lowland peatlands, particularly those developed on poorly drained mineral substrates, are a key locus of elevated CH4 emission to the atmosphere that must be considered for a complete understanding of high latitude CH4 dynamics. |
format |
Text |
author |
Johnston, Carmel E. Ewing, Stephanie A. Harden, Jennifer W. Varner, Ruth K. Wickland, Kimberly P. Koch, Joshua C. Fuller, Christopher C. Manies, Kristen Jorgenson, M. Torre |
spellingShingle |
Johnston, Carmel E. Ewing, Stephanie A. Harden, Jennifer W. Varner, Ruth K. Wickland, Kimberly P. Koch, Joshua C. Fuller, Christopher C. Manies, Kristen Jorgenson, M. Torre Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence |
author_facet |
Johnston, Carmel E. Ewing, Stephanie A. Harden, Jennifer W. Varner, Ruth K. Wickland, Kimberly P. Koch, Joshua C. Fuller, Christopher C. Manies, Kristen Jorgenson, M. Torre |
author_sort |
Johnston, Carmel E. |
title |
Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence |
title_short |
Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence |
title_full |
Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence |
title_fullStr |
Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence |
title_full_unstemmed |
Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence |
title_sort |
effect of permafrost thaw on co2 and ch4 exchange in a western alaska peatland chronosequence |
publisher |
University of New Hampshire Scholars' Repository |
publishDate |
2014 |
url |
https://scholars.unh.edu/faculty_pubs/402 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1401&context=faculty_pubs |
genre |
permafrost Thermokarst Alaska |
genre_facet |
permafrost Thermokarst Alaska |
op_source |
Faculty Publications |
op_relation |
https://scholars.unh.edu/faculty_pubs/402 https://scholars.unh.edu/cgi/viewcontent.cgi?article=1401&context=faculty_pubs |
op_rights |
© 2014 IOP Publishing Ltd. |
_version_ |
1766165133560643584 |