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Vulnerability and resilience of the carbon exchange of a subarctic peatland to an extreme winter event

Parmentier, Frans Jan W. LU ; Rasse, Daniel P.; Lund, Magnus LU ; Bjerke, Jarle W.; Drake, Bert G.; Weldon, Simon; Tømmervik, Hans and Hansen, Georg H. (2018) In Environmental Research Letters 13(6).
Abstract

Extreme winter events that damage vegetation are considered an important climatic cause of arctic browning - a reversal of the greening trend of the region - and possibly reduce the carbon uptake of northern ecosystems. Confirmation of a reduction in CO2 uptake due to winter damage, however, remains elusive due to a lack of flux measurements from affected ecosystems. In this study, we report eddy covariance fluxes of CO2 from a peatland in northern Norway and show that vegetation CO2 uptake was delayed and reduced in the summer of 2014 following an extreme winter event earlier that year. Strong frost in the absence of a protective snow cover - its combined intensity unprecedented in the local climate... (More)

Extreme winter events that damage vegetation are considered an important climatic cause of arctic browning - a reversal of the greening trend of the region - and possibly reduce the carbon uptake of northern ecosystems. Confirmation of a reduction in CO2 uptake due to winter damage, however, remains elusive due to a lack of flux measurements from affected ecosystems. In this study, we report eddy covariance fluxes of CO2 from a peatland in northern Norway and show that vegetation CO2 uptake was delayed and reduced in the summer of 2014 following an extreme winter event earlier that year. Strong frost in the absence of a protective snow cover - its combined intensity unprecedented in the local climate record - caused severe dieback of the dwarf shrub species Calluna vulgaris and Empetrum nigrum. Similar vegetation damage was reported at the time along ∼1000 km of coastal Norway, showing the widespread impact of this event. Our results indicate that gross primary production (GPP) exhibited a delayed response to temperature following snowmelt. From snowmelt up to the peak of summer, this reduced carbon uptake by 14 (0-24) g C m-2 (∼12% of GPP in that period) - similar to the effect of interannual variations in summer weather. Concurrently, remotely-sensed NDVI dropped to the lowest level in more than a decade. However, bulk photosynthesis was eventually stimulated by the warm and sunny summer, raising total GPP. Species other than the vulnerable shrubs were probably resilient to the extreme winter event. The warm summer also increased ecosystem respiration, which limited net carbon uptake. This study shows that damage from a single extreme winter event can have an ecosystem-wide impact on CO2 uptake, and highlights the importance of including winter-induced shrub damage in terrestrial ecosystem models to accurately predict trends in vegetation productivity and carbon sequestration in the Arctic and sub-Arctic.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
arctic browning, carbon cycle, CO exchange, eddy covariance, northern ecosystems, extreme winter event
in
Environmental Research Letters
volume
13
issue
6
pages
11 pages
publisher
IOP Publishing
external identifiers
  • scopus:85049789712
ISSN
1748-9318
DOI
10.1088/1748-9326/aabff3
language
English
LU publication?
yes
id
84b9ece7-7630-4a26-8758-2e1df59186f7
date added to LUP
2018-08-17 11:48:36
date last changed
2019-02-20 11:24:20
@article{84b9ece7-7630-4a26-8758-2e1df59186f7,
  abstract     = {<p>Extreme winter events that damage vegetation are considered an important climatic cause of arctic browning - a reversal of the greening trend of the region - and possibly reduce the carbon uptake of northern ecosystems. Confirmation of a reduction in CO<sub>2</sub> uptake due to winter damage, however, remains elusive due to a lack of flux measurements from affected ecosystems. In this study, we report eddy covariance fluxes of CO<sub>2</sub> from a peatland in northern Norway and show that vegetation CO<sub>2</sub> uptake was delayed and reduced in the summer of 2014 following an extreme winter event earlier that year. Strong frost in the absence of a protective snow cover - its combined intensity unprecedented in the local climate record - caused severe dieback of the dwarf shrub species Calluna vulgaris and Empetrum nigrum. Similar vegetation damage was reported at the time along ∼1000 km of coastal Norway, showing the widespread impact of this event. Our results indicate that gross primary production (GPP) exhibited a delayed response to temperature following snowmelt. From snowmelt up to the peak of summer, this reduced carbon uptake by 14 (0-24) g C m<sup>-2</sup> (∼12% of GPP in that period) - similar to the effect of interannual variations in summer weather. Concurrently, remotely-sensed NDVI dropped to the lowest level in more than a decade. However, bulk photosynthesis was eventually stimulated by the warm and sunny summer, raising total GPP. Species other than the vulnerable shrubs were probably resilient to the extreme winter event. The warm summer also increased ecosystem respiration, which limited net carbon uptake. This study shows that damage from a single extreme winter event can have an ecosystem-wide impact on CO<sub>2</sub> uptake, and highlights the importance of including winter-induced shrub damage in terrestrial ecosystem models to accurately predict trends in vegetation productivity and carbon sequestration in the Arctic and sub-Arctic.</p>},
  articleno    = {065009},
  author       = {Parmentier, Frans Jan W. and Rasse, Daniel P. and Lund, Magnus and Bjerke, Jarle W. and Drake, Bert G. and Weldon, Simon and Tømmervik, Hans and Hansen, Georg H.},
  issn         = {1748-9318},
  keyword      = {arctic browning,carbon cycle,CO exchange,eddy covariance, northern ecosystems,extreme winter event},
  language     = {eng},
  month        = {06},
  number       = {6},
  pages        = {11},
  publisher    = {IOP Publishing},
  series       = {Environmental Research Letters},
  title        = {Vulnerability and resilience of the carbon exchange of a subarctic peatland to an extreme winter event},
  url          = {http://dx.doi.org/10.1088/1748-9326/aabff3},
  volume       = {13},
  year         = {2018},
}