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Exchange of CO2 in Arctic tundra : Impacts of meteorological variations and biological disturbance

López-Blanco, Efrén; Lund, Magnus LU ; Williams, Mathew; Tamstorf, Mikkel P.; Westergaard-Nielsen, Andreas; Exbrayat, Jean François; Hansen, Birger U. and Christensen, Torben R. LU (2017) In Biogeosciences 14(19). p.4467-4483
Abstract

An improvement in our process-based understanding of carbon (C) exchange in the Arctic and its climate sensitivity is critically needed for understanding the response of tundra ecosystems to a changing climate. In this context, we analysed the net ecosystem exchange (NEE) of CO2 in West Greenland tundra (64°N) across eight snow-free periods in 8 consecutive years, and characterized the key processes of net ecosystem exchange and its two main modulating components: gross primary production (GPP) and ecosystem respiration (Reco). Overall, the ecosystem acted as a consistent sink of CO2, accumulating g'30g dagger;Cg'2 on average (range of g'17 to g'41gdagger;Cg'2) during the years 2008-2015, except 2011 (source of 41gdagger;Cg'2), which... (More)

An improvement in our process-based understanding of carbon (C) exchange in the Arctic and its climate sensitivity is critically needed for understanding the response of tundra ecosystems to a changing climate. In this context, we analysed the net ecosystem exchange (NEE) of CO2 in West Greenland tundra (64°N) across eight snow-free periods in 8 consecutive years, and characterized the key processes of net ecosystem exchange and its two main modulating components: gross primary production (GPP) and ecosystem respiration (Reco). Overall, the ecosystem acted as a consistent sink of CO2, accumulating g'30g dagger;Cg'2 on average (range of g'17 to g'41gdagger;Cg'2) during the years 2008-2015, except 2011 (source of 41gdagger;Cg'2), which was associated with a major pest outbreak. The results do not reveal a marked meteorological effect on the net CO2 uptake despite the high interannual variability in the timing of snowmelt and the start and duration of the growing season. The ranges in annual GPP (g'182 to g'316gdagger;Cg'2) and Reco (144 to 279gdagger;Cg'2) were > 5 fold larger than the range in NEE. Gross fluxes were also more variable (coefficients of variation are 3.6 and 4.1% respectively) than for NEE (0.7%). GPP and Reco were sensitive to insolation and temperature, and there was a tendency towards larger GPP and Reco during warmer and wetter years. The relative lack of sensitivity of NEE to meteorology was a result of the correlated response of GPP and Reco. During the snow-free season of the anomalous year of 2011, a biological disturbance related to a larvae outbreak reduced GPP more strongly than Reco. With continued warming temperatures and longer growing seasons, tundra systems will increase rates of C cycling. However, shifts in sink strength will likely be triggered by factors such as biological disturbances, events that will challenge our forecasting of C states.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biogeosciences
volume
14
issue
19
pages
17 pages
publisher
Copernicus Publications
external identifiers
  • scopus:85031313530
  • wos:000412734600001
ISSN
1726-4170
DOI
10.5194/bg-14-4467-2017
language
English
LU publication?
yes
id
003ed543-62f4-49fc-b661-e051cc695473
date added to LUP
2017-10-26 14:04:45
date last changed
2018-11-11 04:57:21
@article{003ed543-62f4-49fc-b661-e051cc695473,
  abstract     = {<p>An improvement in our process-based understanding of carbon (C) exchange in the Arctic and its climate sensitivity is critically needed for understanding the response of tundra ecosystems to a changing climate. In this context, we analysed the net ecosystem exchange (NEE) of CO2 in West Greenland tundra (64°N) across eight snow-free periods in 8 consecutive years, and characterized the key processes of net ecosystem exchange and its two main modulating components: gross primary production (GPP) and ecosystem respiration (Reco). Overall, the ecosystem acted as a consistent sink of CO2, accumulating g'30g dagger;Cg'2 on average (range of g'17 to g'41gdagger;Cg'2) during the years 2008-2015, except 2011 (source of 41gdagger;Cg'2), which was associated with a major pest outbreak. The results do not reveal a marked meteorological effect on the net CO2 uptake despite the high interannual variability in the timing of snowmelt and the start and duration of the growing season. The ranges in annual GPP (g'182 to g'316gdagger;Cg'2) and Reco (144 to 279gdagger;Cg'2) were &amp;gt; 5 fold larger than the range in NEE. Gross fluxes were also more variable (coefficients of variation are 3.6 and 4.1% respectively) than for NEE (0.7%). GPP and Reco were sensitive to insolation and temperature, and there was a tendency towards larger GPP and Reco during warmer and wetter years. The relative lack of sensitivity of NEE to meteorology was a result of the correlated response of GPP and Reco. During the snow-free season of the anomalous year of 2011, a biological disturbance related to a larvae outbreak reduced GPP more strongly than Reco. With continued warming temperatures and longer growing seasons, tundra systems will increase rates of C cycling. However, shifts in sink strength will likely be triggered by factors such as biological disturbances, events that will challenge our forecasting of C states.</p>},
  author       = {López-Blanco, Efrén and Lund, Magnus and Williams, Mathew and Tamstorf, Mikkel P. and Westergaard-Nielsen, Andreas and Exbrayat, Jean François and Hansen, Birger U. and Christensen, Torben R.},
  issn         = {1726-4170},
  language     = {eng},
  month        = {10},
  number       = {19},
  pages        = {4467--4483},
  publisher    = {Copernicus Publications},
  series       = {Biogeosciences},
  title        = {Exchange of CO<sub>2</sub> in Arctic tundra : Impacts of meteorological variations and biological disturbance},
  url          = {http://dx.doi.org/10.5194/bg-14-4467-2017},
  volume       = {14},
  year         = {2017},
}