Long term carbon dioxide exchange above a mixed forest in the Belgian Ardennes

Aubinet, Marc; Chermanne, B; Vandenhaute, M.; Longdoz, Bernard; Yernaux, Michel; Laitat, Eric

doi:10.1016/s0168-1923(01)00244-1

Cited by 372 publications

(225 citation statements)

References 52 publications

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“…Many studies continue to use the rectangular hyperbola (Wofsy et al, 1993;Aubinet et al, 2001;Pilegaard et al, 2001) including those focusing on remote sensing (Ruimy et al, 1995;Xiao, 2006). By using 10-day periods for parameter estimation, one loses the hysteresis effect and can mask the curvature of the diurnal light response (Biscoe et al, 1975;Ham et al, 1995;Gilmanov et al, 2003) but, again, if using the results presented here in continental scale models, only a restricted amount of information can be incorporated and as few parameters as possible is desirable.…”

Section: Discussionmentioning

confidence: 99%

Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions

Owen¹,

Tenhunen²,

Reichstein³

et al. 2007

Global Change Biol

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Section: Discussionmentioning

confidence: 99%

Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions

Owen¹,

Tenhunen²,

Reichstein³

et al. 2007

Global Change Biol

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“…Of course, these soil respiration values cannot be directly compared to those of the ER obtained using an eddy-covariance system for similar sites because the latter includes the aerial vegetation respiration. However, as the soil respiration is generally the major component of ER (Aubinet et al 2001;Davidson et al 2006b), it appears relevant that a high soil respiration leads also to a high ER measured by an eddy-covariance technique and therefore a higher ER d found for the two investigated sites, especially during the wet season (Figs. 8e and 9b-e).…”

Section: Larger Ecosystem Respiration (Er) For the Forest Than Savannahmentioning

confidence: 96%

“…(1) below as the algebraic sum of the turbulent flux (F CO2 ) measured by the eddy-covariance system and the CO 2 storage flux change in the air below the measurement point, considering the additional terms negligible (Aubinet et al 2001). The storage flux was computed using a single measurement point of the CO 2 concentration at a height of 18 m (forest) and 4.95 m (savannah) as applied in several studies in the Africa region by several authors (Archibald et al 2009;Merbold et al 2009;Ago et al 2014Ago et al , 2015.…”

Section: Data Treatment Analysis and Uncertainty Evaluationmentioning

confidence: 99%

“…We used the Misterlich equation, Eq. (2), to describe the daytime fluxes responses as a function of the photosynthetic photon flux density (Q) (Aubinet et al 2001) taking into account the SWC influence through a simple linear function expressed by Eq. (3) as obtained by Ago et al (2014):…”

Section: Data Treatment Analysis and Uncertainty Evaluationmentioning

confidence: 99%

“…Therefore, in order to analyze the main factors affecting the transfers atmosphere-ecosystems of the CO 2 and water vapor, the canopy conductance, g c (mm s −1 ) was estimated assuming the big-leaf hypothesis (Monteith and Unsworth 2013) and the inverting Penman-Monteith equation (Eq. 5) for the whole dry days at radiation saturation conditions (Q > 1000 μmol m −2 s −1 ) during the entire flux measurements period as described by Aubinet et al (2001):…”

Section: Data Treatment Analysis and Uncertainty Evaluationmentioning

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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Distributed Evaluation of Local Sensitivity Analysis (DELSA), with application to hydrologic models

Rakovec¹,

et al. 2014

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[1] This paper presents a hybrid local-global sensitivity analysis method termed the Distributed Evaluation of Local Sensitivity Analysis (DELSA), which is used here to identify important and unimportant parameters and evaluate how model parameter importance changes as parameter values change. DELSA uses derivative-based ''local'' methods to obtain the distribution of parameter sensitivity across the parameter space, which promotes consideration of sensitivity analysis results in the context of simulated dynamics. This work presents DELSA, discusses how it relates to existing methods, and uses two hydrologic test cases to compare its performance with the popular global, variance-based Sobol' method. The first test case is a simple nonlinear reservoir model with two parameters. The second test case involves five alternative ''bucket-style'' hydrologic models with up to 14 parameters applied to a medium-sized catchment (200 km 2 ) in the Belgian Ardennes. Results show that in both examples, Sobol' and DELSA identify similar important and unimportant parameters, with DELSA enabling more detailed insight at much lower computational cost. For example, in the real-world problem the time delay in runoff is the most important parameter in all models, but DELSA shows that for about 20% of parameter sets it is not important at all and alternative mechanisms and parameters dominate. Moreover, the time delay was identified as important in regions producing poor model fits, whereas other parameters were identified as more important in regions of the parameter space producing better model fits. The ability to understand how parameter importance varies through parameter space is critical to inform decisions about, for example, additional data collection and model development. The ability to perform such analyses with modest computational requirements provides exciting opportunities to evaluate complicated models as well as many alternative models.

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Long term carbon dioxide exchange above a mixed forest in the Belgian Ardennes

Cited by 372 publications

References 52 publications

Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions

Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions

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

Distributed Evaluation of Local Sensitivity Analysis (DELSA), with application to hydrologic models

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