Interactions between light and plant architecture in an agroforestry walnut tree

Dynamic simulation of agroforestry systems requires models of light-vegetation interactions in the tree crown, because of their consequences on tree architecture. We analysed light relations in the crown of a 20-year-old walnut tree grown in an agroforestry system, including the effect of foliage display on light gradients and the tree response to light microclimate. Firstly, the three-dimensional (3D) architecture of the tree was measured using a 3D digitising device. Secondly, a light transfer model was used to simulate leaf irradiance distribution within the crown at a shoot scale. Finally, a preliminary study of the determinants of shoot vigour variability was performed from correlation analysis between shoot diameter and shoot location parameters. (Résumé d'auteur