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Spatiotemporal variability in carbon exchange fluxes across the Sahel

Tagesson, Torbern LU ; Fensholt, Rasmus; Cappelaere, Bernard; Mougin, Eric; Horion, Stéphanie; Kergoat, Laurent; Nieto, Héctor; Mbow, Cheikh; Ehammer, Andrea and Demarty, Jérôme, et al. (2016) In Agricultural and Forest Meteorology 226-227. p.108-118
Abstract

Semi-arid regions play an increasingly important role as a sink within the global carbon (C) cycle and is the main biome driving inter-annual variability in carbon dioxide (CO2) uptake by terrestrial ecosystems. This indicates the need for detailed studies of spatiotemporal variability in C cycling for semi-arid ecosystems. We have synthesized data on the land-atmosphere exchange of CO2 measured with the eddy covariance technique from the six existing sites across the Sahel, one of the largest semi-arid regions in the world. The overall aim of the study is to analyse and quantify the spatiotemporal variability in these fluxes and to analyse to which degree spatiotemporal variation can be explained by hydrological,... (More)

Semi-arid regions play an increasingly important role as a sink within the global carbon (C) cycle and is the main biome driving inter-annual variability in carbon dioxide (CO2) uptake by terrestrial ecosystems. This indicates the need for detailed studies of spatiotemporal variability in C cycling for semi-arid ecosystems. We have synthesized data on the land-atmosphere exchange of CO2 measured with the eddy covariance technique from the six existing sites across the Sahel, one of the largest semi-arid regions in the world. The overall aim of the study is to analyse and quantify the spatiotemporal variability in these fluxes and to analyse to which degree spatiotemporal variation can be explained by hydrological, climatic, edaphic and vegetation variables. All ecosystems were C sinks (average ± total error -162 ± 48 g C m-2 y-1), but were smaller when strongly impacted by anthropogenic influences. Spatial and inter-annual variability in the C flux processes indicated a strong resilience to dry conditions, and were correlated with phenological metrics. Gross primary productivity (GPP) was the most important flux process affecting the sink strength, and diurnal variability in GPP was regulated by incoming radiation, whereas seasonal dynamics was closely coupled with phenology, and soil water content. Diurnal variability in ecosystem respiration was regulated by GPP, whereas seasonal variability was strongly coupled to phenology and GPP. A budget for the entire Sahel indicated a strong C sink mitigating the global anthropogenic C emissions. Global circulation models project an increase in temperature, whereas rainfall is projected to decrease for western Sahel and increase for the eastern part, indicating that the C sink will possibly decrease and increase for the western and eastern Sahel, respectively.

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organization
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Contribution to journal
publication status
published
subject
keywords
Carbon dioxide, Climate change, Dryland, Net ecosystem exchange, Photosynthesis, Respiration
in
Agricultural and Forest Meteorology
volume
226-227
pages
11 pages
publisher
Elsevier
external identifiers
  • Scopus:84975452626
ISSN
0168-1923
DOI
10.1016/j.agrformet.2016.05.013
language
English
LU publication?
yes
id
bc39a862-addf-44bf-9990-bc3082654879
date added to LUP
2016-10-14 11:13:54
date last changed
2016-11-14 12:48:24
@misc{bc39a862-addf-44bf-9990-bc3082654879,
  abstract     = {<p>Semi-arid regions play an increasingly important role as a sink within the global carbon (C) cycle and is the main biome driving inter-annual variability in carbon dioxide (CO<sub>2</sub>) uptake by terrestrial ecosystems. This indicates the need for detailed studies of spatiotemporal variability in C cycling for semi-arid ecosystems. We have synthesized data on the land-atmosphere exchange of CO<sub>2</sub> measured with the eddy covariance technique from the six existing sites across the Sahel, one of the largest semi-arid regions in the world. The overall aim of the study is to analyse and quantify the spatiotemporal variability in these fluxes and to analyse to which degree spatiotemporal variation can be explained by hydrological, climatic, edaphic and vegetation variables. All ecosystems were C sinks (average ± total error -162 ± 48 g C m<sup>-2</sup> y<sup>-1</sup>), but were smaller when strongly impacted by anthropogenic influences. Spatial and inter-annual variability in the C flux processes indicated a strong resilience to dry conditions, and were correlated with phenological metrics. Gross primary productivity (GPP) was the most important flux process affecting the sink strength, and diurnal variability in GPP was regulated by incoming radiation, whereas seasonal dynamics was closely coupled with phenology, and soil water content. Diurnal variability in ecosystem respiration was regulated by GPP, whereas seasonal variability was strongly coupled to phenology and GPP. A budget for the entire Sahel indicated a strong C sink mitigating the global anthropogenic C emissions. Global circulation models project an increase in temperature, whereas rainfall is projected to decrease for western Sahel and increase for the eastern part, indicating that the C sink will possibly decrease and increase for the western and eastern Sahel, respectively.</p>},
  author       = {Tagesson, Torbern and Fensholt, Rasmus and Cappelaere, Bernard and Mougin, Eric and Horion, Stéphanie and Kergoat, Laurent and Nieto, Héctor and Mbow, Cheikh and Ehammer, Andrea and Demarty, Jérôme and Ardö, Jonas},
  issn         = {0168-1923},
  keyword      = {Carbon dioxide,Climate change,Dryland,Net ecosystem exchange,Photosynthesis,Respiration},
  language     = {eng},
  month        = {10},
  pages        = {108--118},
  publisher    = {ARRAY(0xaec63a0)},
  series       = {Agricultural and Forest Meteorology},
  title        = {Spatiotemporal variability in carbon exchange fluxes across the Sahel},
  url          = {http://dx.doi.org/10.1016/j.agrformet.2016.05.013},
  volume       = {226-227},
  year         = {2016},
}