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CO2 and CH4 exchanges between moist moss tundra and atmosphere on Kapp Linné, Svalbard

Lindroth, Anders LU orcid ; Pirk, Norbert LU ; Jónsdóttir, Ingibjörg S. ; Stiegler, Christian LU ; Klemedtsson, Leif and Nilsson, Mats B. (2022) In Biogeosciences 19(16). p.3921-3934
Abstract

We measured CO2 and CH4 fluxes using chambers and eddy covariance (only CO2) from a moist moss tundra in Svalbard. The average net ecosystem exchange (NEE) during the summer (9 June–31 August) was negative (sink), with −0.139 ± 0.032 µmol m−2 s−1 corresponding to −11.8 g C m−2 for the whole summer. The cumulated NEE over the whole growing season (day no. 160 to 284) was −2.5 g C m−2. The CH4 flux during the summer period showed a large spatial and temporal variability. The mean value of all 214 samples was 0.000511 ± 0.000315 µmol m−2 s−1, which corresponds to a growing season estimate of 0.04 to 0.16 g CH4... (More)

We measured CO2 and CH4 fluxes using chambers and eddy covariance (only CO2) from a moist moss tundra in Svalbard. The average net ecosystem exchange (NEE) during the summer (9 June–31 August) was negative (sink), with −0.139 ± 0.032 µmol m−2 s−1 corresponding to −11.8 g C m−2 for the whole summer. The cumulated NEE over the whole growing season (day no. 160 to 284) was −2.5 g C m−2. The CH4 flux during the summer period showed a large spatial and temporal variability. The mean value of all 214 samples was 0.000511 ± 0.000315 µmol m−2 s−1, which corresponds to a growing season estimate of 0.04 to 0.16 g CH4 m−2. Thus, we find that this moss tundra ecosystem is closely in balance with the atmosphere during the growing season when regarding exchanges of CO2 and CH4. The sink of CO2 and the source of CH4 are small in comparison with other tundra ecosystems in the high Arctic. Air temperature, soil moisture and the greenness index contributed significantly to explaining the variation in ecosystem respiration (Reco), while active layer depth, soil moisture and the greenness index were the variables that best explained CH4 emissions. An estimate of temperature sensitivity of Reco and gross primary productivity (GPP) showed that the sensitivity is slightly higher for GPP than for Reco in the interval 0–4.5 ◦C; thereafter, the difference is small up to about 6 ◦C and then begins to rise rapidly for Reco. The consequence of this, for a small increase in air temperature of 1◦ (all other variables assumed unchanged), was that the respiration increased more than photosynthesis turning the small sink into a small source (4.5 g C m−2) during the growing season. Thus, we cannot rule out that the reason why the moss tundra is close to balance today is an effect of the warming that has already taken place in Svalbard.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biogeosciences
volume
19
issue
16
pages
14 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:85137827441
ISSN
1726-4170
DOI
10.5194/bg-19-3921-2022
language
English
LU publication?
yes
id
feb95d83-247d-4ec3-82d2-acf5cf16a524
date added to LUP
2022-12-02 13:48:21
date last changed
2024-06-27 15:34:52
@article{feb95d83-247d-4ec3-82d2-acf5cf16a524,
  abstract     = {{<p>We measured CO<sub>2</sub> and CH<sub>4</sub> fluxes using chambers and eddy covariance (only CO<sub>2</sub>) from a moist moss tundra in Svalbard. The average net ecosystem exchange (NEE) during the summer (9 June–31 August) was negative (sink), with −0.139 ± 0.032 µmol m<sup>−2</sup> s<sup>−1</sup> corresponding to −11.8 g C m<sup>−2</sup> for the whole summer. The cumulated NEE over the whole growing season (day no. 160 to 284) was −2.5 g C m<sup>−2</sup>. The CH<sub>4</sub> flux during the summer period showed a large spatial and temporal variability. The mean value of all 214 samples was 0.000511 ± 0.000315 µmol m<sup>−2</sup> s<sup>−1</sup>, which corresponds to a growing season estimate of 0.04 to 0.16 g CH<sub>4</sub> m<sup>−2</sup>. Thus, we find that this moss tundra ecosystem is closely in balance with the atmosphere during the growing season when regarding exchanges of CO<sub>2</sub> and CH<sub>4</sub>. The sink of CO<sub>2</sub> and the source of CH<sub>4</sub> are small in comparison with other tundra ecosystems in the high Arctic. Air temperature, soil moisture and the greenness index contributed significantly to explaining the variation in ecosystem respiration (R<sub>eco</sub>), while active layer depth, soil moisture and the greenness index were the variables that best explained CH<sub>4</sub> emissions. An estimate of temperature sensitivity of R<sub>eco</sub> and gross primary productivity (GPP) showed that the sensitivity is slightly higher for GPP than for R<sub>eco</sub> in the interval 0–4.5 <sup>◦</sup>C; thereafter, the difference is small up to about 6 <sup>◦</sup>C and then begins to rise rapidly for R<sub>eco</sub>. The consequence of this, for a small increase in air temperature of 1<sup>◦</sup> (all other variables assumed unchanged), was that the respiration increased more than photosynthesis turning the small sink into a small source (4.5 g C m<sup>−2</sup>) during the growing season. Thus, we cannot rule out that the reason why the moss tundra is close to balance today is an effect of the warming that has already taken place in Svalbard.</p>}},
  author       = {{Lindroth, Anders and Pirk, Norbert and Jónsdóttir, Ingibjörg S. and Stiegler, Christian and Klemedtsson, Leif and Nilsson, Mats B.}},
  issn         = {{1726-4170}},
  language     = {{eng}},
  month        = {{08}},
  number       = {{16}},
  pages        = {{3921--3934}},
  publisher    = {{Copernicus GmbH}},
  series       = {{Biogeosciences}},
  title        = {{CO<sub>2</sub> and CH<sub>4</sub> exchanges between moist moss tundra and atmosphere on Kapp Linné, Svalbard}},
  url          = {{http://dx.doi.org/10.5194/bg-19-3921-2022}},
  doi          = {{10.5194/bg-19-3921-2022}},
  volume       = {{19}},
  year         = {{2022}},
}