Long term observations of carbon dioxide exchange over cultivated savanna under a Sudanian climate in Benin (West Africa)

Ago, Expedit Evariste; Agbossou, Euloge Kossi; Galle, Sylvie; Cohard, Jean‐Martial; Heinesch, Bernard; Aubinet, Marc

doi:10.1016/j.agrformet.2014.06.005

Cited by 22 publications

(71 citation statements)

References 63 publications

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“…The two gas analyzers were factory calibrated every 2 years. More information on this setup can be found in Ago et al (2014). The CO 2 fluxes …”

Section: Co 2 Flux Measurementsmentioning

confidence: 99%

“…The leaf area index (LAI) time series was obtained by a combination of the satellite LAI products (SEVIRI) and in situ measurements. More details on the LAI estimation method can be found in Ago et al (2014) and Mamadou et al (2014).…”

Section: Climatic and Environmental Measurementsmentioning

confidence: 99%

“…The rainfall (weighing precipitation gauge, OTT; Hydrometry Ltd., Dublin, Ireland) was recorded at a height of 1.2 m. All these variables were sampled at 30 s time step and were averaged at half hour scale. The photosynthetic photon flux density (Q, μmol m −2 s −1 ) was estimated as twice the global radiation (R g , W m −2 ) (Scanlon and Albertson 2004;Boulain et al 2009;Ago et al 2014Ago et al , 2015. The CO 2 fluxes and meteorological conditions data were also available during 18 months, from 1st July 2008 to 31st December 2009.…”

Section: Climatic and Environmental Measurementsmentioning

confidence: 99%

“…However, the wind speeds rarely exceed 3 m s −1 at the two sites. The two sites have been studied by several authors: Ago et al (2014) analyzed the carbon fluxes over the cultivated savannah, while Mamadou et al (2014) and (Guyot et al 2009(Guyot et al , 2012) studied the energy and water vapor fluxes. For the protected forest site, only the fluxes of the energy and water vapor have been investigated by Mamadou (2014).…”

Section: Two Sites' Descriptionmentioning

confidence: 99%

“…Thus, some investigations on responses of CO 2 fluxes and ecosystems properties to main meteorological, physiological, ecological, and anthropogenic factors are necessary. In addition, only a few studies have been reported on long-term CO 2 fluxes and carbon sequestrations in West Africa by several frameworks such as CarboAfrica project and AMMA-CATCH "African Monsoon Multidisciplinary Analysis" and "Couplage de l'Atmosphère Tropicale et du Cycle Hydrologique" observatory, which contributes significantly to the FluxNet network database (http://fluxnet.ornl.gov) (Brümmer et al 2008;Ago et al 2014Ago et al , 2015Tagesson et al 2015;Quansah et al 2015). Our study analyzed the CO 2 fluxes that were measured over a cultivated savannah and a protected forest under a Sudanian climate in northern Benin.…”

Section: Introductionmentioning

confidence: 99%

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Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

Ago

Agbossou

Cohard

et al. 2016

Annals of Forest Science

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& Key message CO 2 fluxes were measured during 18 months in a forest and a savannah in northern Benin. Higher values of carbon fluxes were found during the wet season at each site. A strong dependency of carbon fluxes on water relations was found in two contrasting sites. The forest sequestered 640 ± 50 and the savannah 190 ± 40 g C m −2 year −1 . & Context In West Africa, the main mechanisms or factors governing the dynamics of ecosystems, especially the dynamics of the carbon fluxes and productivity, still remain less known. This study reports the carbon fluxes over two contrasting ecosystems, notably a protected forest (lat 9.79°N, long 1.72°E, alt 414 m) and a cultivated savannah (lat 9.74°N, long 1.60°E, alt 449 m) in northern Benin. The two sites were among those equipped by the AMMA-CATCH observatory and Ouémé 2025 project. & Aims Flux data were analyzed at the daily and seasonal scales in order to understand their controlling variables. We discussed the patterns of CO 2 fluxes and the characteristics of the two ecosystems. The study also focused on the different water usage strategies developed by the two ecosystems since the alternation between dry and wet seasons highly influenced the seasonal dynamics. Finally, the annual carbon sequestration was estimated together with its uncertainty. & Methods The carbon fluxes were measured during 18 months (July 2008-December 2009) by an eddy-covariance system over two contrasting sites in northern Benin. Fluxes data were computed following the standard procedure. The responses of CO 2 fluxes to the principal climatic and edaphic factors, and the canopy conductance were studied. & Results A clear CO 2 fluxes response to main environmental factors was observed, however with difference according to the seasons and vegetation types. The ecosystem respiration showed the highest values during the wet season and a progressive decrease from wet to dry periods. Also, the carbon uptake values were high during the wet period, but Handling Editor: Erwin DreyerContribution of the co-authors Expédit Evariste Ago conducted mainly the data analysis and prepared the manuscript with contributions from all co-authors. The field work with the eddy-covariance technique was carried out by Jean-Martial Cohard and Sylvie Galle who processed the raw data of fluxes. Marc Aubinet and Euloge Kossi Agbossou assisted in the data analyses. All authors read and approved the final manuscript which was submitted. low during the dry period. However, the CO 2 fluxes for the protected forest were always higher than that for the cultivated savannah within each defined period. This was due to the seasonal changes not only in phenology and physiology but also to the acclimation to environmental conditions, especially to the soil water availability. The water use efficiency was influenced by VPD during the day conditions for two ecosystems. However, the VPD response curve of water usage was relatively constant for the protected forest during the transitional and wet seasons. In contrary, for t...

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“…The two gas analyzers were factory calibrated every 2 years. More information on this setup can be found in Ago et al (2014). The CO 2 fluxes …”

Section: Co 2 Flux Measurementsmentioning

confidence: 99%

Section: Climatic and Environmental Measurementsmentioning

confidence: 99%

Section: Climatic and Environmental Measurementsmentioning

confidence: 99%

Section: Two Sites' Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

Ago

Agbossou

Cohard

et al. 2016

Annals of Forest Science

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Dynamics of water vapor and energy exchanges above two contrasting Sudanian climate ecosystems in Northern Benin (West Africa)

et al. 2016

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Natural ecosystems in sub‐Saharan Africa are experiencing intense changes that will probably modify land surface feedbacks and consequently the regional climate. In this study, we have analyzed water vapor (QLE) and sensible heat (QH) fluxes over a woodland (Bellefoungou, BE) and a cultivated area (Nalohou, NA) in the Sudanian climate of Northern Benin, using 2 years (from July 2008 to June 2010) of eddy covariance measurements. The evaporative fraction (EF) response to environmental and surface variables was investigated at seasonal scale. Soil moisture was found to be the main environmental factor controlling energy partitioning. During the wet seasons, EF was rather stable with an average of 0.75 ± 0.07 over the woodland and 0.70 ± 0.025 over the cultivated area. This means that 70–75% of the available energy was changed into actual evapotranspiration during the investigated wet seasons depending on the vegetation type. The cumulative annual actual evapotranspiration (AET) varied between 730 ± 50 mm yr−1 at the NA site and 1040 ± 70 mm yr−1 at the BE site. With similar weather conditions at the two sites, the BE site showed 30% higher AET values than the NA site. The sensible heat flux QH at the cultivated site was always higher than that of the woodland site, but observed differences were much less than those of QLE. In a land surface conversion context, these differences are expected to impact both atmospheric dynamics and the hydrological cycle.

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Turbulence Characteristics in the Atmospheric Surface Layer Over a Heterogeneous Cultivated Surface in a Tropical Region

Hounsinou

Mamadou

Kounouhéwa

2023

Boundary-Layer Meteorol

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Long term observations of carbon dioxide exchange over cultivated savanna under a Sudanian climate in Benin (West Africa)

Cited by 22 publications

References 63 publications

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

Dynamics of water vapor and energy exchanges above two contrasting Sudanian climate ecosystems in Northern Benin (West Africa)

Turbulence Characteristics in the Atmospheric Surface Layer Over a Heterogeneous Cultivated Surface in a Tropical Region

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