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Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance

Olid, Carolina ; Klaminder, Jonatan ; Monteux, Sylvain ; Johansson, Margareta LU and Dorrepaal, Ellen (2020) In Global Change Biology
Abstract
Thicker snowpacks and their insulation effects cause winter‐warming and invoke thaw of permafrost ecosystems. Temperature‐dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow‐free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long‐term net C balance (Net Ecosystem Production) in a sub‐arctic peat plateau subjected to 10‐years experimental winter‐warming. By combining... (More)
Thicker snowpacks and their insulation effects cause winter‐warming and invoke thaw of permafrost ecosystems. Temperature‐dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow‐free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long‐term net C balance (Net Ecosystem Production) in a sub‐arctic peat plateau subjected to 10‐years experimental winter‐warming. By combining 210Pb and 14C dating of peat cores with peat growth models, we investigated thawing effects on year‐round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter‐warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent water logging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long‐term responses of whole‐year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage. (Less)
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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Global Change Biology
pages
34 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85089561458
  • pmid:32681580
ISSN
1354-1013
DOI
10.1111/gcb.15283
language
English
LU publication?
yes
id
8aead3aa-6675-4f6f-8293-c8d877670936
date added to LUP
2020-07-21 08:48:35
date last changed
2022-04-18 23:41:34
@article{8aead3aa-6675-4f6f-8293-c8d877670936,
  abstract     = {{Thicker snowpacks and their insulation effects cause winter‐warming and invoke thaw of permafrost ecosystems. Temperature‐dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow‐free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long‐term net C balance (Net Ecosystem Production) in a sub‐arctic peat plateau subjected to 10‐years experimental winter‐warming. By combining 210Pb and 14C dating of peat cores with peat growth models, we investigated thawing effects on year‐round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter‐warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent water logging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long‐term responses of whole‐year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.}},
  author       = {{Olid, Carolina and Klaminder, Jonatan and Monteux, Sylvain and Johansson, Margareta and Dorrepaal, Ellen}},
  issn         = {{1354-1013}},
  language     = {{eng}},
  month        = {{07}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Global Change Biology}},
  title        = {{Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance}},
  url          = {{http://dx.doi.org/10.1111/gcb.15283}},
  doi          = {{10.1111/gcb.15283}},
  year         = {{2020}},
}