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Evelyne Costes - One of the best experts on this subject based on the ideXlab platform.
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MuSCA: a multi-scale source-sink Carbon Allocation model to 2 explore Carbon Allocation in plants. An application on static apple-tree
Annals of Botany, 2019Co-Authors: Francesco Reyes, Benoit Pallas, Christophe Pradal, Federico Vaggi, D Zanotelli, Tagliavini Marco, D. Gianelle, Evelyne CostesAbstract:Background and aims : Carbon Allocation in plants is usually represented at a topological scale, specific to each model. This makes the results obtained with different models, and the impact of their scales of representation, difficult to compare. In this study, we developed a multi-scale Carbon Allocation model (MuSCA) that allows the use of different, user-defined, topological scales of a plant, and assessment of the impact of each spatial scale on simulated results and computation time. Methods : Model multi-scale consistency and behaviour were tested on three realistic apple tree structures. Carbon Allocation was computed at five scales, spanning from the metamer (the finest scale, used as a reference) up to first-order branches, and for different values of a sap friction coefficient. Fruit dry mass increments were compared across spatial scales and with field data. Key Results : The model was able to represent effects of competition for Carbon assimilates on fruit growth. Intermediate friction parameter values provided results that best fitted field data. Fruit growth simulated at the metamer scale differed of ~1 % in respect to results obtained at growth unit scale and up to 60 % in respect to first order branch and fruiting unit scales. Generally, the coarser the spatial scale the more predicted fruit growth diverged from the reference. Coherence in fruit growth across scales was also differentially impacted, depending on the tree structure considered. Decreasing the topological resolution reduced computation time by up to four orders of magnitude. Conclusions : MuSCA revealed that the topological scale has a major influence on the simulation of Carbon Allocation. This suggests that the scale should be a factor that is carefully evaluated when using a Carbon Allocation model, or when comparing results produced by different models. Finally, with MuSCA, trade-off between computation time and prediction accuracy can be evaluated by changing topological scales.
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MuSCA: a multi-scale model to explore Carbon Allocation in plants
2018Co-Authors: Francesco Reyes, Benoit Pallas, Christophe Pradal, Federico Vaggi, D Zanotelli, D. Gianelle, M Tagliavini, Evelyne CostesAbstract:Background and aims: Carbon Allocation in plants is usually represented at a specific spatial scale, peculiar to each model. This makes the results obtained by different models, and the impact of their scale of representation, difficult to compare. In this work we developed a Multi Scale Carbon Allocation model (MuSCA) that can be applied at different, user-defined, topological scales of a plant, and used to assess the impact of each spatial scale on simulated results and computation time. Methods: Model multi-scale consistency and behavior were tested by applications on three realistic apple tree structures. Carbon Allocation was computed at five spatial scales, spanning from the metamer (the finest scale, used as a reference) up to 1st order branches, and for different values of a sap friction coefficient. Fruit dry mass increments were compared across spatial scales and with field data. Key Results: The model showed physiological coherence in representing competition for Carbon assimilates. Results from intermediate values of the friction parameter best fitted the field data. For these, fruit growth simulated at the metamer scale (considered as a reference) differed from about 1% at growth unit scale up to 35% at first order branch scale. Generally, the coarser the spatial scale the more fruit growth diverged from the reference and the lower the obtained within-tree fruit growth variability. Coherence in the Carbon allocated across scales was also differently impacted, depending on the tree structure considered. Decreasing the topological resolution reduced computation time up to four orders of magnitude. Conclusions: MuSCA revealed that the topological scale has a major influence on the simulation of Carbon Allocation, suggesting that this factor should be carefully evaluated when using different Carbon Allocation models or comparing their results. Trades-off between computation time and prediction accuracy can be evaluated by changing topological scales.
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coupling the functional structural plant models mapplet and qualitree to simulate Carbon Allocation and growth variability of apple trees
Acta Horticulturae, 2017Co-Authors: Benoit Pallas, Michel Génard, Gilles Vercambre, David Da Silva, Weiwei Yang, O Guillaume, Pierreeric Lauri, Pierre Valsesia, Evelyne CostesAbstract:Plant growth highly depends on the Carbon Allocation which results from combined effects of environment, horticultural practices and management. QualiTree has been demonstrated to be a useful model to simulate Carbon Allocation in peach trees. The objective of this study was to adapt QualiTree to apple trees to simulate Carbon economy and organ growth dynamics as well as their within-tree variability. We used MappleT to generate tree architectures corresponding to the 'Fuji' cultivar and to account for the variability among individuals. Architectures were saved into a Multiscale Tree Graph (MTG) that included information on all shoot and fruit locations as well as their initial weights. This information was then used as input for QualiTree. Furthermore, based on the observed shoot polymorphism in apple trees, we modified QualiTree to take into account different classes of shoots (long, medium and short) that are characterized by different growth rates and duration. The light interception sub-model, based on a turbid medium hypothesis, was also modified to allow the usage of user-defined ellipsoids to represent the shape of apple trees. The simulations were compared to 3D digitized trees and measurements previously performed on 'Fuji' apple trees. The model was useful for simulating organ growth and their within tree variability. This modelling approach coupling MAppleT and QualiTree will help provide deeper understanding of complex interactions between growth, architecture and management practices. To reach this objective, further works are needed to integrate into MappleT retroaction loops between Carbon Allocation and plant architecture dynamics.
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Exploring Carbon Allocation with a multi-scale model: the case of apple
2016Co-Authors: Francesco Reyes, Benoit Pallas, Christophe Pradal, M Tagliavini, D Zanotelli, Frédéric Boudon, F Vaggi, M. Saudreau, D. Gianelle, Evelyne CostesAbstract:Understanding the Allocation of carbohydrates among organs is necessary to predict plant growth in relation to climatic conditions and agronomic practices. Despite the large number of studies on the subject of Carbon Allocation, no clear consensus exists on (i) the most appropriate topological scale (organ, metamer, compartment...) to represent this process on complex plant structures, and (ii) the importance of distances between organs in Carbon transport. In this study, we implemented a generic source-sink based Carbon Allocation model, following the equation of the SIMWAL model, that takes into account the distances between sources and sinks, the sink strength and the availability of carbohydrates from photosynthesis. Our model makes use of multi-scale tree graph (MTG) to represent geometry and topology of a tree structure at different scales. Starting from the description of a plant at a given scale (e.g. metamer and growing unit scales), we defined additional grouping criteria (fruiting branches and main axis) that were used to represent the plant structure, and the process of Carbon Allocation at different spatial resolutions. Generic functions to determine the biomass and Carbon demand of the individual organs described in an MTG were implemented and calibrated for apple trees (Fuji variety) by means of age and organ type dependent allometric equations and maximum potential Relative Growth Rate curves (RGR) obtained in a field experiment. Photosynthesis for individual leaves of the input MTG was estimated by means of a radiative model (RATP). The model was then applied to architectural mock-ups in the MTG format produced by the MappleT model, representing trees with high and low fruit loads. Simulations on simplified plant structures qualitatively showed the influence of the scale of representation and of the distance parameter on the predicted Carbon Allocation. In order to test assumptions regarding the effect of distance, the source-sink behavior and the suitability of the alternative scales of representation for predicting Carbon Allocation, the variability and spatial distribution of the simulated RGR were compared to field observations. Finally, a benchmarking was performed to compare the computational efficiency of the model when running at different scales. The presented multiscale model provides a framework to re-interpret the plant topology in order to test the influence of some assumptions at the basis of the Carbon Allocation process, such as branch autonomy or the effect of distance. It is also a mean to investigate the trade-offs between the detail at which a plant is described, and the accuracy and computational efficiency in predicting Carbon Allocation. The present work was developed on the OpenAlea platform, and will provide existing Functional Structural Plant Models with a new generic model to simulate Carbon Allocation in plants.
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Exploring Carbon Allocation with a multi-scale model: the case of apple
2016Co-Authors: Francisco Reyes, Benoit Pallas, Christophe Pradal, Federico Vaggi, D Zanotelli, D. Gianelle, M Tagliavini, Frédéric Boudon, M. Saudreau, Evelyne CostesAbstract:Understanding the Allocation of carbohydrates among organs is necessary to predict plant growth in relation to climatic conditions and agronomic practices. Despite the large number of studies on the subject of Carbon Allocation, no clear consensus exists on (i) the most appropriate topological scale (organ, metamer, compartment...) to represent this process on complex plant structures, and (ii) the importance of distances between organs in Carbon transport. In this study, we implemented a generic source-sink based Carbon Allocation model, following the equation of the SIMWAL model, that takes into account the distances between sources and sinks, the sink strength and the availability of carbohydrates from photosynthesis. Our model makes use of multi-scale tree graph (MTG) to represent geometry and topology of a tree structure at different scales. Starting from the description of a plant at a given scale (e.g. metamer and growing unit scales), we defined additional grouping criteria (fruiting branches and main axis) that were used to represent the plant structure, and the process of Carbon Allocation at different spatial resolutions. Generic functions to determine the biomass and Carbon demand of the individual organs described in an MTG were implemented and calibrated for apple trees (Fuji variety) by means of age and organ type dependent allometric equations and maximum potential Relative Growth Rate curves (RGR) obtained in a field experiment. Photosynthesis for individual leaves of the input MTG was estimated by means of a radiative model (RATP). The model was then applied to architectural mock-ups in the MTG format produced by the MappleT model, representing trees with high and low fruit loads. Simulations on simplified plant structures qualitatively showed the influence of the scale of representation and of the distance parameter on the predicted Carbon Allocation. In order to test assumptions regarding the effect of distance, the source-sink behavior and the suitability of the alternative scales of representation for predicting Carbon Allocation, the variability and spatial distribution of the simulated RGR were compared to field observations. Finally, a benchmarking was performed to compare the computational efficiency of the model when running at different scales. The presented multiscale model provides a framework to re-interpret the plant topology in order to test the influence of some assumptions at the basis of the Carbon Allocation process, such as branch autonomy or the effect of distance. It is also a mean to investigate the trade-offs between the detail at which a plant is described, and the accuracy and computational efficiency in predicting Carbon Allocation. The present work was developed on the OpenAlea platform, and will provide existing Functional Structural Plant Models with a new generic model to simulate Carbon Allocation in plants. (Texte integral)
Megan K Bartlett - One of the best experts on this subject based on the ideXlab platform.
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climate and plant trait strategies determine tree Carbon Allocation to leaves and mediate future forest productivity
Global Change Biology, 2019Co-Authors: Anna T Trugman, Leander D L Anderegg, Brett T Wolfe, Benjamin Birami, Nadine K Ruehr, Matteo Detto, Megan K BartlettAbstract:Forest leaf area has enormous leverage on the Carbon cycle because it mediates both forest productivity and resilience to climate extremes. Despite widespread evidence that trees are capable of adjusting to changes in environment across both space and time through modifying Carbon Allocation to leaves, many vegetation models use fixed Carbon Allocation schemes independent of environment, which introduces large uncertainties into predictions of future forest responses to atmospheric CO2 fertilization and anthropogenic climate change. Here, we develop an optimization-based model, whereby tree Carbon Allocation to leaves is an emergent property of environment and plant hydraulic traits. Using a combination of meta-analysis, observational datasets, and model predictions, we find strong evidence that optimal hydraulic-Carbon coupling explains observed patterns in leaf Allocation across large environmental and CO2 concentration gradients. Furthermore, testing the sensitivity of leaf Allocation strategy to a diversity in hydraulic and economic spectrum physiological traits, we show that plant hydraulic traits in particular have an enormous impact on the global change response of forest leaf area. Our results provide a rigorous theoretical underpinning for improving Carbon cycle predictions through advancing model predictions of leaf area, and underscore that tree-level Carbon Allocation to leaves should be derived from first principles using mechanistic plant hydraulic processes in the next generation of vegetation models.
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Tree Carbon Allocation explains forest drought-kill and recovery patterns.
Ecology letters, 2018Co-Authors: Anna T Trugman, Matteo Detto, Megan K Bartlett, David Medvigy, William R. L. Anderegg, Christopher R. Schwalm, Bruce Schaffer, Stephen W. PacalaAbstract:The mechanisms governing tree drought mortality and recovery remain a subject of inquiry and active debate given their role in the terrestrial Carbon cycle and their concomitant impact on climate change. Counter-intuitively, many trees do not die during the drought itself. Indeed, observations globally have documented that trees often grow for several years after drought before mortality. A combination of meta-analysis and tree physiological models demonstrate that optimal Carbon Allocation after drought explains observed patterns of delayed tree mortality and provides a predictive recovery framework. Specifically, post-drought, trees attempt to repair water transport tissue and achieve positive Carbon balance through regrowing drought-damaged xylem. Furthermore, the number of years of xylem regrowth required to recover function increases with tree size, explaining why drought mortality increases with size. These results indicate that tree resilience to drought-kill may increase in the future, provided that CO2 fertilisation facilitates more rapid xylem regrowth.
Jinliang Chen - One of the best experts on this subject based on the ideXlab platform.
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SUGAR Model-Assisted Analysis of Carbon Allocation and Transformation in Tomato Fruit Under Different Water Along With Potassium Conditions.
Frontiers in plant science, 2020Co-Authors: Anrong Luo, Shaozhong Kang, Jinliang ChenAbstract:Carbohydrate concentration is closely related to water and mineral nutrition in fruits; water stress and minerals alter the assimilation, operation and distribution of carbohydrates, thereby affecting fruit quality. In order to explore the dynamic effects of different water and potassium conditions on photoassimilates in fruit growth and development, we analyzed the variation of Carbon during the whole growth stage based on relevant experimental data and the SUGAR model. Also, we quantitatively studied the distribution of photoassimilates such as structural carbohydrates, soluble sugars, and starch in fruit and their response to water and potassium supply. Firstly, the results showed that the Carbon Allocation and transformation dynamically changed during the whole growth stage; in fact, the variation trend of Carbon was the same under different water and potassium conditions, and the main Carbon Allocation at the early stages was due to the accumulation of starch and other compounds. The relative rate of Carbon conversion of soluble sugars to other compounds (k3) and that of soluble sugars to starch (k5m) dropped during the whole growth stage. Also, the Carbon in the form of starch was converted to soluble sugars and Carbon was mainly distributed as soluble sugars at maturity; mainly owing to sugar accumulation, k3(t) and k5m(t) approached 0 at the end of the growth stage. Secondly, it was found that applying potassium can significantly increase the Carbon Allocation and transformation into soluble sugars during the whole growth stage, especially there was a remarkable significant difference between potassium and without potassium application treatments at the fruit maturation stage; while the Carbon conversion coefficients k3(t) and k5m(t) were reduced accompanied by fruit development. Finally, we concluded that water deficit can regulate the Carbon Allocation of fruits and significantly increase the Carbon content of fruits in the form of starch and soluble sugars; therefore, it reduced the Carbon content of the other compounds in the fruit and improved the fruit quality.
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SUGAR model-assisted analysis of Carbon Allocation and transformation in tomato fruit under different water along with potassium conditions
Frontiers in Plant Science, 2020Co-Authors: Anrong Luo, Shaozhong Kang, Jinliang ChenAbstract:Carbohydrate concentrations in fruit are closely related to the availability of water and mineral nutrients. Water stress and minerals alter the assimilation, operation, and distribution of carbohydrates, thereby affecting the fruit quality. The SUGAR model was used to investigate the Carbon balance in tomato fruit during different growth stages when available water was varied and potassium added. Further, we quantitatively studied the distribution of photoassimilates such as structural carbohydrates, soluble sugars, and starch in fruit and evaluated their response to water and potassium supply. The results revealed that the Carbon Allocation and transformation dynamically changed during the all growth stages; in fact, variation in Carbon content showed similar trends for different water along with potassium treatments, Carbon Allocation during the early development stages was mainly to starch and structural Carbon compounds. The relative rate of Carbon conversion of soluble sugars to structural Carbon compounds (k(3)) and of soluble sugars to starch (k(5m)) peaked during the initial stage and then dropped during fruit growth and development stages. Carbon was primarily allocated as soluble sugars and starch was converted to soluble sugars at fruit maturation.k(3)(t) andk(5m)(t) approached zero at the end of the growth stage, mainly due to sugar accumulation. Potassium application can significantly raise Carbon flows imported (C-supply) from the phloem into the fruit and thus increased Carbon Allocation to soluble sugars over the entire growth period. Potassium addition during the fruit maturation stage decreased the content of starch and other Carbon compounds. Water deficit regulated Carbon Allocation and increased soluble sugar content but reduced structural Carbon content, thereby improving fruit quality.
Anna T Trugman - One of the best experts on this subject based on the ideXlab platform.
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climate and plant trait strategies determine tree Carbon Allocation to leaves and mediate future forest productivity
Global Change Biology, 2019Co-Authors: Anna T Trugman, Leander D L Anderegg, Brett T Wolfe, Benjamin Birami, Nadine K Ruehr, Matteo Detto, Megan K BartlettAbstract:Forest leaf area has enormous leverage on the Carbon cycle because it mediates both forest productivity and resilience to climate extremes. Despite widespread evidence that trees are capable of adjusting to changes in environment across both space and time through modifying Carbon Allocation to leaves, many vegetation models use fixed Carbon Allocation schemes independent of environment, which introduces large uncertainties into predictions of future forest responses to atmospheric CO2 fertilization and anthropogenic climate change. Here, we develop an optimization-based model, whereby tree Carbon Allocation to leaves is an emergent property of environment and plant hydraulic traits. Using a combination of meta-analysis, observational datasets, and model predictions, we find strong evidence that optimal hydraulic-Carbon coupling explains observed patterns in leaf Allocation across large environmental and CO2 concentration gradients. Furthermore, testing the sensitivity of leaf Allocation strategy to a diversity in hydraulic and economic spectrum physiological traits, we show that plant hydraulic traits in particular have an enormous impact on the global change response of forest leaf area. Our results provide a rigorous theoretical underpinning for improving Carbon cycle predictions through advancing model predictions of leaf area, and underscore that tree-level Carbon Allocation to leaves should be derived from first principles using mechanistic plant hydraulic processes in the next generation of vegetation models.
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Tree Carbon Allocation explains forest drought-kill and recovery patterns.
Ecology letters, 2018Co-Authors: Anna T Trugman, Matteo Detto, Megan K Bartlett, David Medvigy, William R. L. Anderegg, Christopher R. Schwalm, Bruce Schaffer, Stephen W. PacalaAbstract:The mechanisms governing tree drought mortality and recovery remain a subject of inquiry and active debate given their role in the terrestrial Carbon cycle and their concomitant impact on climate change. Counter-intuitively, many trees do not die during the drought itself. Indeed, observations globally have documented that trees often grow for several years after drought before mortality. A combination of meta-analysis and tree physiological models demonstrate that optimal Carbon Allocation after drought explains observed patterns of delayed tree mortality and provides a predictive recovery framework. Specifically, post-drought, trees attempt to repair water transport tissue and achieve positive Carbon balance through regrowing drought-damaged xylem. Furthermore, the number of years of xylem regrowth required to recover function increases with tree size, explaining why drought mortality increases with size. These results indicate that tree resilience to drought-kill may increase in the future, provided that CO2 fertilisation facilitates more rapid xylem regrowth.
David Robinson - One of the best experts on this subject based on the ideXlab platform.
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Allometric constraints on, and trade-offs in, belowground Carbon Allocation and their control of soil respiration across global forest ecosystems.
Global change biology, 2014Co-Authors: Guangshui Chen, Yusheng Yang, David RobinsonAbstract:To fully understand how soil respiration is partitioned among its component fluxes and responds to climate, it is essential to relate it to belowground Carbon Allocation, the ultimate Carbon source for soil respiration. This remains one of the largest gaps in knowledge of terrestrial Carbon cycling. Here, we synthesize data on gross and net primary production and their components, and soil respiration and its components, from a global forest database, to determine mechanisms governing belowground Carbon Allocation and their relationship with soil respiration partitioning and soil respiration responses to climatic factors across global forest ecosystems. Our results revealed that there are three independent mechanisms controlling belowground Carbon Allocation and which influence soil respiration and its partitioning: an allometric constraint; a fine-root production vs. root respiration trade-off; and an above- vs. belowground trade-off in plant Carbon. Global patterns in soil respiration and its partitioning are constrained primarily by the allometric Allocation, which explains some of the previously ambiguous results reported in the literature. Responses of soil respiration and its components to mean annual temperature, precipitation, and nitrogen deposition can be mediated by changes in belowground Carbon Allocation. Soil respiration responds to mean annual temperature overwhelmingly through an increasing belowground Carbon input as a result of extending total day length of growing season, but not by temperature-driven acceleration of soil Carbon decomposition, which argues against the possibility of a strong positive feedback between global warming and soil Carbon loss. Different nitrogen loads can trigger distinct belowground Carbon Allocation mechanisms, which are responsible for different responses of soil respiration to nitrogen addition that have been observed. These results provide new insights into belowground Carbon Allocation, partitioning of soil respiration, and its responses to climate in forest ecosystems and are, therefore, valuable for terrestrial Carbon simulations and projections.