Sensitivity and uncertainty analysis of the carbon and water fluxes at the tree scale in<i>Eucalyptus</i>plantations using a metamodeling approach

Christina, Mathias; Nouvellon, Yann; Laclau, Jean‐Paul; Stape, José Luiz; Campoe, Otávio Camargo; Maire, Guerric le

doi:10.1139/cjfr-2015-0173

Cited by 14 publications

(9 citation statements)

References 75 publications

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“…The balance between the simplicity and accuracy of this metamodel is because the LAD can be considered as a proxy for within crown foliage aggregation, which was determined -along with the LAI -as the most important characteristic to model light penetration by Sampson and Smith (1993). The metamodels for yielded R 2 and RMSE similar to those found in Christina et al (2016): R 2 of 0.87 compared to 0.87 and 0.94 for shade tree and coffee respectively in our study, and an RMSE of 0.20 gC MJ -1 compared to 0.25 and 0.09 (shade tree and coffee resp.) in our study.…”

Section: Metamodelssupporting

confidence: 83%

“…spatial heterogeneity) into one empirical equation, becoming an input for the next crop model. Metamodels are generally used to better understand the processes at stake in a model and to assess model sensitivity and uncertainty (Christina et al, 2016;Faivre et al, 2013), for the purpose of optimization (Razavi et al, 2012), or to make faster and reasonably accurate predictions for a given variable that is usually computed by a time-consuming model, but with fewer simulation errors compared to simpler models (Marie et al, 2014). Metamodels are often used as an efficient and simple tool to combine models at different time and/or space scales without running the finer-scale model iteratively.…”

Section: Introductionmentioning

confidence: 99%

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DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems

Vezy

Maire

Christina

et al. 2020

Environmental Modelling & Software

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The DynACof model was designed to model coffee agroforestry systems and study the trade-offs to e.g. optimize the system facing climate changes. The model simulates net primary productivity (NPP), growth, yield, mortality, energy and water balance of coffee agroforestry systems according to shade tree species and management. Several plot-scale ecosystem services are simulated by the model, such as production, canopy cooling effect, or potential C sequestration. DynACof uses metamodels derived from a detailed 3D process-based model (MAESPA) to account for complex spatial effects, while running fast. It also includes a coffee flower bud and fruit cohort module to better distribute fruit carbon demand over the year, a key feature to obtain a realistic competition between sinks. We compared the model outputs with a highly comprehensive database on a coffee agroforestry farm in Costa Rica. The fluxes simulated by the model were close to the measurements over a 5-year period (RMSE= 1.60 gC m-2 d-1 for gross primary productivity; 0.63 mm d-1 for actual evapo-transpiration, 1.34 MJ m-2 d-1 for sensible heat flux and 1.88 MJ m-2 d-1 for net radiation), and DynACof satisfactorily simulated the yield, NPP, mortality and carbon stock for each coffee organ type over a 35-year rotation.

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Section: Metamodelssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems

Vezy

Maire

Christina

et al. 2020

Environmental Modelling & Software

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“…) and in a sensitivity analysis of the simulated water use efficiency with MAESPA model (Christina et al . ).…”

Section: Discussionmentioning

confidence: 97%

Importance of deep water uptake in tropical eucalypt forest

et al. 2016

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Climate models predict that the frequency, intensity and duration of drought events will increase in tropical regions. Although water withdrawal from deep soil layers is generally considered to be an efficient adaptation to drought, there is little information on the role played by deep roots in tropical forests. Tropical Eucalyptus plantations managed in short rotation cycles are simple forest ecosystems that may provide an insight into the water use by trees in tropical forests. The contribution made by water withdrawn from deep soil layers to the water required for evapotranspiration was quantified daily from planting to harvesting age for a Eucalyptus grandis stand using a soil water transfer model coupled with an ecophysiological forest model (MAESPA). The model was parameterized using an extensive data set and validated using time series of the soil water content down to a depth of 10 m and water-table level, as well as evapotranspiration measured using eddy covariance. Fast root growth after planting provided access to large quantities of water stored in deep soil layers over the first 2 years. Eucalyptus roots reached the water-table at a depth of 12 m after 2 years. Although the mean water withdrawal from depths of over 10 m amounted to only 5% of canopy transpiration from planting to a harvesting age of 5 years, the proportion of water taken up near the water-table was much higher during dry periods. The water-table rose from 18 to 12 m below-ground over 2 years after the harvest of the previous stand and then fell until harvesting age as evapotranspiration rates exceeded the annual rainfall. Deep rooting is an efficient strategy to increase the amount of water available for the trees, allowing the uptake of transient gravitational water and possibly giving access to a deep water-table. Deep soil layers have an important buffer role for large amounts of water stored during the wet season that is taken up by trees during dry periods. Our study confirms that deep rooting could be a major mechanism explaining high transpiration rates throughout the year in many tropical forests. (Résumé d'auteur

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“…Furthermore, detailed 3D light‐interception models in combination with fine‐field NPP measurements could be helpful in calibrating statistical meta‐models, which are useful for scaling plot‐level results up to the regional level (e.g. Christina et al ; Vezy et al ). They also offer a tool for optimizing plot design in order to maximize several functions, such as GPP, water‐use efficiency, LUE and canopy temperature according to microclimate and shade structure.…”

Section: Importance Of Variable Light‐use Efficiency For Modellingmentioning

confidence: 99%

Increased light‐use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system

Charbonnier

Roupsard

Maire

et al. 2017

Plant Cell & Environment

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In agroforestry systems, shade trees strongly affect the physiology of the undergrown crop. However, a major paradigm is that the reduction in absorbed photosynthetically active radiation is, to a certain extent, compensated by an increase in light-use efficiency, thereby reducing the difference in net primary productivity between shaded and non-shaded plants. Due to the large spatial heterogeneity in agroforestry systems and the lack of appropriate tools, the combined effects of such variables have seldom been analysed, even though they may help understand physiological processes underlying yield dynamics. In this study, we monitored net primary productivity, during two years, on scales ranging from individual coffee plants to the entire plot. Absorbed radiation was mapped with a 3D model (MAESPA). Light-use efficiency and net assimilation rate were derived for each coffee plant individually. We found that although irradiance was reduced by 60% below crowns of shade trees, coffee light-use efficiency increased by 50%, leaving net primary productivity fairly stable across all shade levels. Variability of aboveground net primary productivity of coffee plants was caused primarily by the age of the plants and by intraspecific competition among them (drivers usually overlooked in the agroforestry literature) rather than by the presence of shade trees.

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Sensitivity and uncertainty analysis of the carbon and water fluxes at the tree scale inEucalyptusplantations using a metamodeling approach

Cited by 14 publications

References 75 publications

DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems

DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems

Importance of deep water uptake in tropical eucalypt forest

Increased light‐use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system

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