The Experts below are selected from a list of 35949 Experts worldwide ranked by ideXlab platform
Stephen P Long - One of the best experts on this subject based on the ideXlab platform.
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predicting light induced stomatal movements based on the redox state of plastoquinone theory and validation
Photosynthesis Research, 2019Co-Authors: Johannes Kromdijk, Katarzyna Glowacka, Stephen P LongAbstract:Prediction of stomatal conductance is a key element to relate and scale up leaf-level gas exchange processes to canopy, ecosystem and land surface models. The empirical models that are typically employed for this purpose are simple and elegant formulations which relate stomatal conductance on a leaf area basis to the net rate of CO2 assimilation, humidity and CO2 concentration. Although light intensity is not directly modelled as a stomatal opening cue, it is well-known that stomata respond strongly to light. One response mode depends specifically on the blue-light part of the light spectrum, whereas the quantitative or 'red' light response is less spectrally defined and relies more on the quantity of incident light. Here, we present a modification of an empirical stomatal conductance model which explicitly accounts for the stomatal red-light response, based on a mesophyll-derived signal putatively initiated by the chloroplastic plastoquinone redox state. The modified model showed similar prediction accuracy compared to models using a relationship between stomatal conductance and net assimilation rate. However, Fitted Parameter values with the modified model varied much less across different measurement conditions, lessening the need for frequent re-Parameterization to different conditions required of the current model. We also present a simple and easy to Parameterize extension to the widely used Farquhar-Von Caemmerer-Berry photosynthesis model to facilitate coupling with the modified stomatal conductance model, which should enable use of the new stomatal conductance model to simulate ecosystem water vapour exchange in terrestrial biosphere models.
Katarzyna Glowacka - One of the best experts on this subject based on the ideXlab platform.
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predicting light induced stomatal movements based on the redox state of plastoquinone theory and validation
Photosynthesis Research, 2019Co-Authors: Johannes Kromdijk, Katarzyna Glowacka, Stephen P LongAbstract:Prediction of stomatal conductance is a key element to relate and scale up leaf-level gas exchange processes to canopy, ecosystem and land surface models. The empirical models that are typically employed for this purpose are simple and elegant formulations which relate stomatal conductance on a leaf area basis to the net rate of CO2 assimilation, humidity and CO2 concentration. Although light intensity is not directly modelled as a stomatal opening cue, it is well-known that stomata respond strongly to light. One response mode depends specifically on the blue-light part of the light spectrum, whereas the quantitative or 'red' light response is less spectrally defined and relies more on the quantity of incident light. Here, we present a modification of an empirical stomatal conductance model which explicitly accounts for the stomatal red-light response, based on a mesophyll-derived signal putatively initiated by the chloroplastic plastoquinone redox state. The modified model showed similar prediction accuracy compared to models using a relationship between stomatal conductance and net assimilation rate. However, Fitted Parameter values with the modified model varied much less across different measurement conditions, lessening the need for frequent re-Parameterization to different conditions required of the current model. We also present a simple and easy to Parameterize extension to the widely used Farquhar-Von Caemmerer-Berry photosynthesis model to facilitate coupling with the modified stomatal conductance model, which should enable use of the new stomatal conductance model to simulate ecosystem water vapour exchange in terrestrial biosphere models.
Johannes Kromdijk - One of the best experts on this subject based on the ideXlab platform.
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predicting light induced stomatal movements based on the redox state of plastoquinone theory and validation
Photosynthesis Research, 2019Co-Authors: Johannes Kromdijk, Katarzyna Glowacka, Stephen P LongAbstract:Prediction of stomatal conductance is a key element to relate and scale up leaf-level gas exchange processes to canopy, ecosystem and land surface models. The empirical models that are typically employed for this purpose are simple and elegant formulations which relate stomatal conductance on a leaf area basis to the net rate of CO2 assimilation, humidity and CO2 concentration. Although light intensity is not directly modelled as a stomatal opening cue, it is well-known that stomata respond strongly to light. One response mode depends specifically on the blue-light part of the light spectrum, whereas the quantitative or 'red' light response is less spectrally defined and relies more on the quantity of incident light. Here, we present a modification of an empirical stomatal conductance model which explicitly accounts for the stomatal red-light response, based on a mesophyll-derived signal putatively initiated by the chloroplastic plastoquinone redox state. The modified model showed similar prediction accuracy compared to models using a relationship between stomatal conductance and net assimilation rate. However, Fitted Parameter values with the modified model varied much less across different measurement conditions, lessening the need for frequent re-Parameterization to different conditions required of the current model. We also present a simple and easy to Parameterize extension to the widely used Farquhar-Von Caemmerer-Berry photosynthesis model to facilitate coupling with the modified stomatal conductance model, which should enable use of the new stomatal conductance model to simulate ecosystem water vapour exchange in terrestrial biosphere models.
Serge Andréfouët - One of the best experts on this subject based on the ideXlab platform.
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Impact of environmental variability on Pinctada margaritifera life-history traits: A full life cycle deb modeling approach
Ecological Modelling, 2020Co-Authors: Nathanaël Sangare, Alain Lo-yat, Gilles Le Moullac, Laure Pecquerie, Yoann Thomas, Sébastien Lefebvre, Romain Le Gendre, Benoit Beliaeff, Serge AndréfouëtAbstract:The black-lipped pearl oyster (Pinctada margaritifera) is extensively farmed in French Polynesia to produce black pearls. For a sustainable management of marine resources, studying interactions between organisms and environment, and the associated factors and processes that will impact their life cycle and thus modulate population dynamics is a major research priority. Here, we describe black-lipped pearl oyster energy acquisition and use, and its control by temperature and food concentration within the Dynamic Energy Budget (DEB) theory framework. The model parametrization was based on literature data and a specific laboratory experiment. Model validation was carried out thanks to historical in-situ datasets and a dedicated field survey. Three theoretical environmental scenarios were built to investigate the response of the pearl oyster to environmental variations. We successfully modeled a wide range of life-stage-specific traits and processes, especially the delayed acceleration of growth after settlement. Applying the model on field data collected at three different culture sites required only one free-Fitted Parameter, the half saturation coefficient Xk, which controls how ingestion depends on food density. Xk integrates all variations linked to the trophic environment. Analysis of the kinetics of energy fluxes under theoretical environmental scenarios suggests that temperature variations induce seasonality of reproduction in a species thought to spawn opportunistically throughout the whole year. The major influence of food concentration fluctuations on growth rate and reproductive effort is highlighted. The model showed the lower performances associated with recovery time between food-rich and starvation periods. The implications of these findings in the context of black pearl farming in a changing environment are discussed.
Nathanaël Sangare - One of the best experts on this subject based on the ideXlab platform.
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Impact of environmental variability on Pinctada margaritifera life-history traits: A full life cycle deb modeling approach
Ecological Modelling, 2020Co-Authors: Nathanaël Sangare, Alain Lo-yat, Gilles Le Moullac, Laure Pecquerie, Yoann Thomas, Sébastien Lefebvre, Romain Le Gendre, Benoit Beliaeff, Serge AndréfouëtAbstract:The black-lipped pearl oyster (Pinctada margaritifera) is extensively farmed in French Polynesia to produce black pearls. For a sustainable management of marine resources, studying interactions between organisms and environment, and the associated factors and processes that will impact their life cycle and thus modulate population dynamics is a major research priority. Here, we describe black-lipped pearl oyster energy acquisition and use, and its control by temperature and food concentration within the Dynamic Energy Budget (DEB) theory framework. The model parametrization was based on literature data and a specific laboratory experiment. Model validation was carried out thanks to historical in-situ datasets and a dedicated field survey. Three theoretical environmental scenarios were built to investigate the response of the pearl oyster to environmental variations. We successfully modeled a wide range of life-stage-specific traits and processes, especially the delayed acceleration of growth after settlement. Applying the model on field data collected at three different culture sites required only one free-Fitted Parameter, the half saturation coefficient Xk, which controls how ingestion depends on food density. Xk integrates all variations linked to the trophic environment. Analysis of the kinetics of energy fluxes under theoretical environmental scenarios suggests that temperature variations induce seasonality of reproduction in a species thought to spawn opportunistically throughout the whole year. The major influence of food concentration fluctuations on growth rate and reproductive effort is highlighted. The model showed the lower performances associated with recovery time between food-rich and starvation periods. The implications of these findings in the context of black pearl farming in a changing environment are discussed.