Modeling gas exchange and biomass production in West African Sahelian and Sudanian ecological zones

Rahimi Jaber, Evariste Ago Expedit, Ayantunde Augustine, Berger Sina, Bogaert Jan, Butterbach-Bahh Klaus, Cappelaere Bernard, Cohard Jean-Martial, Demarty Jérôme, Diouf Abdoul Aziz, Falk Ulrike, Haas Edwin, Hiernaux Pierre, Kraus David, Roupsard Olivier, Scheer Clemens, Srivastava Amit Kumar, Tagesson Torbern, Grote Rüdiger. 2021. Modeling gas exchange and biomass production in West African Sahelian and Sudanian ecological zones. GeoScientific Model Development, 14 (6) : 3789-3812.

https://doi.org/10.5194/gmd-14-3789-2021

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Url - jeu de données - Entrepôt autre : https://doi.org/10.35097/437 / Url - jeu de données - Entrepôt autre : https://doi.org/10.35097/438

Quartile : Q1, Sujet : GEOSCIENCES, MULTIDISCIPLINARY

Résumé : West African Sahelian and Sudanian ecosystems provide essential services to people and also play a significant role within the global carbon cycle. However, climate and land use are dynamically changing, and uncertainty remains with respect to how these changes will affect the potential of these regions to provide food and fodder resources or how they will affect the biosphere–atmosphere exchange of CO2. In this study, we investigate the capacity of a process-based biogeochemical model, LandscapeDNDC, to simulate net ecosystem exchange (NEE) and aboveground biomass of typical managed and natural Sahelian and Sudanian savanna ecosystems. In order to improve the simulation of phenology, we introduced soil-water availability as a common driver of foliage development and productivity for all of these systems. The new approach was tested by using a sample of sites (calibration sites) that provided NEE from flux tower observations as well as leaf area index data from satellite images (MODIS, MODerate resolution Imaging Spectroradiometer). For assessing the simulation accuracy, we applied the calibrated model to 42 additional sites (validation sites) across West Africa for which measured aboveground biomass data were available. The model showed good performance regarding biomass of crops, grass, or trees, yielding correlation coefficients of 0.82, 0.94, and 0.77 and root-mean-square errors of 0.15, 0.22, and 0.12 kg m−2, respectively. The simulations indicate aboveground carbon stocks of up to 0.17, 0.33, and 0.54 kg C ha−1 m−2 for agricultural, savanna grasslands, and savanna mixed tree–grassland sites, respectively. Carbon stocks and exchange rates were particularly correlated with the abundance of trees, and grass biomass and crop yields were higher under more humid climatic conditions. Our study shows the capability of LandscapeDNDC to accurately simulate carbon balances in natural and agricultural ecosystems in semiarid West Africa under a wide range of conditions; thus, the model could be used to assess the impact of land-use and climate change on the regional biomass productivity.

Mots-clés Agrovoc : cycle du carbone, modèle de simulation, échange gazeux, changement climatique, Sorghum bicolor, rendement des cultures, services écosystémiques, couverture végétale, zone semi-aride, évaluation de l'impact, carbone

Mots-clés géographiques Agrovoc : Afrique occidentale, Sénégal, Mali, Bénin

Champ stratégique Cirad : CTS 1 (2019-) - Biodiversité

Agences de financement européennes : European Commission

Agences de financement hors UE : African Union Commission

Projets sur financement : (EU) Upscaling Site-Specific Climate-smart Agriculture and Land use practices to Enhance Regional production Systems in West Africa

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