A double-digitising method for building 3D virtual trees with non-planar leaves: application to the morphology and light-capture properties of young beech trees (Fagus sylvatica)

185 18 Number of tables: 2 19 Number of figures: 10 20 doi : 10.1071/FP08051 2/35 Abstract 21 We developed a double-digitizing method combining a hand-held electromagnetic digitizer 22 and a non-contact three-dimensional (3D) laser scanner. The former was used to record the 23 positions of all leaves in a tree and orientation angles of their lamina. The latter served to 24 obtain the morphology of leaves sampled in the tree. As the scanner outputs a cloud of points, 25 software was developed to reconstruct non-planar (NP) leaves composed of triangles, and to 26 compute numerical shape parameters: midrib curvature, torsion and transversal curvature of 27 the lamina. Combination of both methods allowed building 3D virtual trees with NP leaves. 28 The method was applied to young beech trees (Fagus sylvatica) selected in different sunlight 29 environments (from 1 to 100% of incident light) in forest of central France. Leaf morphology 30 responded to light availability, with more bent shape in well lit leaves. Light interception at 31 the leaf scale by NP leaves was decreased from 4 to 10%, for shaded and sunlit leaves 32 compared to planar leaves. At the tree scale, light interception by trees made of NP leaves was 33 decreased by 1 to 3% for 100% to 1% light, respectively. 34 35