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Eddy covariance measurements reveal a decreased carbon sequestration strength 2010–2022 in an African semiarid savanna

Wieckowski, Aleksander LU orcid ; Vestin, Patrik LU orcid ; Ardö, Jonas LU orcid ; Roupsard, Olivier ; Ndiaye, Ousmane ; Diatta, Ousmane ; Ba, Seydina ; Agbohessou, Yélognissè ; Fensholt, Rasmus and Verbruggen, Wim , et al. (2024) In Global Change Biology 30(9).
Abstract

Monitoring the changes of ecosystem functioning is pivotal for understanding the global carbon cycle. Despite its size and contribution to the global carbon cycle, Africa is largely understudied in regard to ongoing changes of its ecosystem functioning and their responses to climate change. One of the reasons is the lack of long-term in situ data. Here, we use eddy covariance to quantify the net ecosystem exchange (NEE) and its components—gross primary production (GPP) and ecosystem respiration (Reco) for years 2010–2022 for a Sahelian semiarid savanna to study trends in the fluxes. Significant negative trends were found for NEE (12.7 ± 2.8 g C m2 year−1), GPP (39.6 ± 7.9 g C m2... (More)

Monitoring the changes of ecosystem functioning is pivotal for understanding the global carbon cycle. Despite its size and contribution to the global carbon cycle, Africa is largely understudied in regard to ongoing changes of its ecosystem functioning and their responses to climate change. One of the reasons is the lack of long-term in situ data. Here, we use eddy covariance to quantify the net ecosystem exchange (NEE) and its components—gross primary production (GPP) and ecosystem respiration (Reco) for years 2010–2022 for a Sahelian semiarid savanna to study trends in the fluxes. Significant negative trends were found for NEE (12.7 ± 2.8 g C m2 year−1), GPP (39.6 ± 7.9 g C m2 year−1), and Reco (32.2 ± 8.9 g C m2 year−1). We found that NEE decreased by 60% over the study period, and this decrease was mainly caused by stronger negative trends in rainy season GPP than in Reco. Additionally, we observed strong increasing trends in vapor pressure deficit, but no trends in rainfall or soil water content. Thus, a proposed explanation for the decrease in carbon sink strength is increasing atmospheric dryness. The warming climate in the Sahel, coupled with increasing evaporative demand, may thus lead to decreased GPP levels across this biome, and lowering its CO2 sequestration.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
carbon loss, climate change, eddy covariance, rainfall, Sahel, semiarid savanna, vapor pressure deficit, water availability
in
Global Change Biology
volume
30
issue
9
article number
e17509
publisher
Wiley-Blackwell
external identifiers
  • pmid:39323398
  • scopus:85204940835
ISSN
1354-1013
DOI
10.1111/gcb.17509
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd.
id
2cc4a963-f767-4195-9846-1e58a44848cf
date added to LUP
2024-12-04 20:25:25
date last changed
2025-07-03 14:22:55
@article{2cc4a963-f767-4195-9846-1e58a44848cf,
  abstract     = {{<p>Monitoring the changes of ecosystem functioning is pivotal for understanding the global carbon cycle. Despite its size and contribution to the global carbon cycle, Africa is largely understudied in regard to ongoing changes of its ecosystem functioning and their responses to climate change. One of the reasons is the lack of long-term in situ data. Here, we use eddy covariance to quantify the net ecosystem exchange (NEE) and its components—gross primary production (GPP) and ecosystem respiration (R<sub>eco</sub>) for years 2010–2022 for a Sahelian semiarid savanna to study trends in the fluxes. Significant negative trends were found for NEE (12.7 ± 2.8 g C m<sup>2</sup> year<sup>−1</sup>), GPP (39.6 ± 7.9 g C m<sup>2</sup> year<sup>−1</sup>), and R<sub>eco</sub> (32.2 ± 8.9 g C m<sup>2</sup> year<sup>−1</sup>). We found that NEE decreased by 60% over the study period, and this decrease was mainly caused by stronger negative trends in rainy season GPP than in R<sub>eco</sub>. Additionally, we observed strong increasing trends in vapor pressure deficit, but no trends in rainfall or soil water content. Thus, a proposed explanation for the decrease in carbon sink strength is increasing atmospheric dryness. The warming climate in the Sahel, coupled with increasing evaporative demand, may thus lead to decreased GPP levels across this biome, and lowering its CO<sub>2</sub> sequestration.</p>}},
  author       = {{Wieckowski, Aleksander and Vestin, Patrik and Ardö, Jonas and Roupsard, Olivier and Ndiaye, Ousmane and Diatta, Ousmane and Ba, Seydina and Agbohessou, Yélognissè and Fensholt, Rasmus and Verbruggen, Wim and Gebremedhn, Haftay Hailu and Tagesson, Torbern}},
  issn         = {{1354-1013}},
  keywords     = {{carbon loss; climate change; eddy covariance; rainfall; Sahel; semiarid savanna; vapor pressure deficit; water availability}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{9}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Global Change Biology}},
  title        = {{Eddy covariance measurements reveal a decreased carbon sequestration strength 2010–2022 in an African semiarid savanna}},
  url          = {{http://dx.doi.org/10.1111/gcb.17509}},
  doi          = {{10.1111/gcb.17509}},
  volume       = {{30}},
  year         = {{2024}},
}