Drivers and vertical CO2 flux balances in a Sahelian agroforestry system : insights from high frequency measurements

2026

Article référencé dans le Web of Science WOS:001747146400001

Ba S. M., Roupsard O., Chapuis Lardy Lydie, Bouvery F., Agbohessou Y., Duthoit M., Wieckowski A., Tagesson T., Assouma M., Gaglo E., Delon C., Sambou B., Serca Dominique

Soil, 2026, 12 (1), p. 471-495 ISSN 2199-3971

Agroforestry systems - combining trees with crops and/or livestock - are increasingly promoted as sustainable and climate-resilient land-use strategies. Despite their widespread presence in the Sahel, experimental data on their potential as carbon sinks are scarce. This study presents a full-year, high-frequency dataset of CO2 fluxes in a Sahelian agro-silvo-pastoral parkland dominated by Faidherbia albida, located in Senegal's groundnut basin. CO2 fluxes were continuously measured using automated dynamic chambers, allowing the quantification of soil and crop respiration (Rch), gross primary production (GPPch), and net carbon exchange (FCO2ch) under both full sun and shaded (under tree canopies) environments. Seasonal patterns of CO2 fluxes were similar in both environments, with peaks during the rainy season. Rch and GPPch were significantly higher under tree canopies, indicating a "fertile island" effect. CO2 flux variability was primarily driven by soil moisture and leaf area index. Chamber-based GPP estimates closely matched those from Eddy Covariance measurements. On an annual scale, F. albida trees contributed approximately 23 % of total ecosystem GPP, with a carbon use efficiency of 0.48. Net annual vertical CO2 exchange was estimated at -1.4 +/- 0.46 and -1.8 +/- 0.17 Mg C-CO2 ha-1 using chamber and Eddy Covariance methods, respectively. These findings underscore the role of F. albida-based agroforestry systems as effective carbon sinks in Sahelian landscapes, supporting their potential contribution to climate change mitigation.

Pédologie [068]

SENEGAL ; ZONE SAHELIENNE

Fonds IRD [F B010097054]

fdi:010097054