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Spatiotemporal variability in carbon exchange fluxes across the Sahel

Author:
  • Torbern Tagesson
  • Rasmus Fensholt
  • Bernard Cappelaere
  • Eric Mougin
  • Stéphanie Horion
  • Laurent Kergoat
  • Héctor Nieto
  • Cheikh Mbow
  • Andrea Ehammer
  • Jérôme Demarty
  • Jonas Ardö
Publishing year: 2016-10-15
Language: English
Pages: 108-118
Publication/Series: Agricultural and Forest Meteorology
Volume: 226-227
Document type: Journal article
Publisher: Elsevier

Abstract english

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.

Keywords

  • Meteorology and Atmospheric Sciences
  • Environmental Sciences related to Agriculture and Land-use
  • Carbon dioxide
  • Climate change
  • Dryland
  • Net ecosystem exchange
  • Photosynthesis
  • Respiration

Other

Published
  • ISSN: 0168-1923
E-mail: jonas [dot] ardo [at] nateko [dot] lu [dot] se

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Dept of Physical Geography and Ecosystem Science

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Dept of Physical Geography and Ecosystem Science

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Department of Physical Geography and Ecosystem Science
Lund University
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Sweden

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