Etude expérimentale du sol-plante-atmosphère continuum

par Roberta Dainese

Projet de thèse en Ecologie fonctionnelle

Sous la direction de Thierry Fourcaud.

Thèses en préparation à Montpellier en cotutelle avec l'Université de Strathclyde , dans le cadre de Biodiversité, Agriculture, Alimentation, Environnement, Terre, Eau (Montpellier ; École Doctorale ; 2015-...) , en partenariat avec AMAP - botAnique et Modélisation de l'Architecture des Plantes et des végétations (laboratoire) depuis le 01-10-2016 .


  • Résumé

    The basic idea is to create an infiltration column to monitor the hydraulics of the SPAC, focusing on the evapo-transpiration rate and the suction profile of the system. A model will be developed to simulate the behaviour of the infiltration column. Several steps will be necessary to achieve the validation of the model: Task 1 – Explore the use of high-capacity tensiometer and filter paper to monitor plant water potential in the xylem and leaves respectively. Validate measurements against ‘Scholander pressure chamber' and psychrometer (WP4) measurements. These instruments have been used for years in geotechnique, but the application on plants is completely new. This choice comes from the acknowledgement of useful features of the instruments and a working principle behind them that allow us to use them even on plants. Task 2 – Investigate the features of micro-flow in the xylem using a combination of Neutron and X-Ray tomography (to validate the xylem water potential measurement using the HCT). Task 3 – Design and implement an infiltration column (approximately 30 cm diameter and 30cm/1m high) where: i) the total evapo-transpiration of the system is monitored recording the water loss over time with a balance ii) the status of the soil is monitored using TDR probes (volumetric water content) and High-capacity tensiometers (soil negative pore-water pressure) iii) the status of the plant is monitored using a stem-flow heat-dissipation meter and balance (water flow), Scholander pressure chamber, WP4C, High-Capacity Tensiometers and filter papers for the water potential in roots, leaves and trunk/stem. Task 4 – Perform experimental tests changing conditions of the system: i) Soil: to understand the change in suction profile related to different grain size distributions and water retention curves (University of Strathclyde); ii) Atmosphere: to understand the change in suction profile and evapo-transpiration related to different boundary conditions in the atmosphere, i.e. irradiation, ventilation, relative humidity of the air, etc. (University of Strathclyde); iii) Vegetation: to understand how the presence of different species and root architectures can change the hydraulics of the system. At this stage, tests will investigate the behaviour related to: a. Vegetated and non-vegetated soil; b. Different herbaceous species; c. Presence of young trees; The aim is to understand how the vegetation type, root architecture (including root density and root depth) and the plant growth affect the suction profile, the water content within the soil (UMR AMAP, Montpellier). Task 5 – Interpret experimental data on the basis of the quantitative SPAC model and revise/refine the model in the light of the experimental data.

  • Titre traduit

    Experimental investigation of the Soil-Plant –Atmosphere continuum


  • Résumé

    The basic idea is to create an infiltration column to monitor the hydraulics of the SPAC, focusing on the evapo-transpiration rate and the suction profile of the system. A model will be developed to simulate the behaviour of the infiltration column. Several steps will be necessary to achieve the validation of the model: Task 1 – Explore the use of high-capacity tensiometer and filter paper to monitor plant water potential in the xylem and leaves respectively. Validate measurements against ‘Scholander pressure chamber' and psychrometer (WP4) measurements. These instruments have been used for years in geotechnique, but the application on plants is completely new. This choice comes from the acknowledgement of useful features of the instruments and a working principle behind them that allow us to use them even on plants. Task 2 – Investigate the features of micro-flow in the xylem using a combination of Neutron and X-Ray tomography (to validate the xylem water potential measurement using the HCT). Task 3 – Design and implement an infiltration column (approximately 30 cm diameter and 30cm/1m high) where: i) the total evapo-transpiration of the system is monitored recording the water loss over time with a balance ii) the status of the soil is monitored using TDR probes (volumetric water content) and High-capacity tensiometers (soil negative pore-water pressure) iii) the status of the plant is monitored using a stem-flow heat-dissipation meter and balance (water flow), Scholander pressure chamber, WP4C, High-Capacity Tensiometers and filter papers for the water potential in roots, leaves and trunk/stem. Task 4 – Perform experimental tests changing conditions of the system: i) Soil: to understand the change in suction profile related to different grain size distributions and water retention curves (University of Strathclyde); ii) Atmosphere: to understand the change in suction profile and evapo-transpiration related to different boundary conditions in the atmosphere, i.e. irradiation, ventilation, relative humidity of the air, etc. (University of Strathclyde); iii) Vegetation: to understand how the presence of different species and root architectures can change the hydraulics of the system. At this stage, tests will investigate the behaviour related to: a. Vegetated and non-vegetated soil; b. Different herbaceous species; c. Presence of young trees; The aim is to understand how the vegetation type, root architecture (including root density and root depth) and the plant growth affect the suction profile, the water content within the soil (UMR AMAP, Montpellier). Task 5 – Interpret experimental data on the basis of the quantitative SPAC model and revise/refine the model in the light of the experimental data.