Reconstruction of phyllotaxis at the example of digitized red mangrove (Rhizophora mangle) and application to light interception simulation

The function of the arrangement of leaves (phyllotaxy) in a plant, increases its ability to perform photosynthesis by positioning the leaves to maximize the surface area available to intercept sunlight. In mangroves species, phyllotaxis is an unexplored phenomenon with the exception of early work from Tomlinson and Wheat. Available red mangrove models do not provide the needed flexibility in representation of tree architecture, which is needed to analyze and reconstruct the detailed architecture of saplings. The objective of the current study was to generate the phyllotactic pattern for red mangrove saplings (Rhizophora mangle L) based on our 3D digitized model, in situ measurements, photographic analysis, and using an algorithm. Onsite mangrove saplings (between 1 and 2.5 m) from Turneffe Atoll, Belize, were photographed. The above-ground part was digitized using the electromagnetic digitizing equipment (FASTRAK ® Polhemus Inc.), high-resolution photos of the leaf arrangements were taken along with field notes, and the model was constructed using the software GroIMP. Our algorithm, enriched by probabilistic approaches for the purpose of handling perturbations in phyllotactic patterns, was able to closely refoliate our 3D model. We then used the resulting hybrid model, composed of the digitized branching structure and the algorithmically-generated leaves, to simulate the interception of light by individual leaves, employing the stochastic raytracing-based radiation model. This preliminary result allows us to assess and visualize the photosynthetic contributions of single leaves throughout the canopy. Simulations of other processes (flows in xylem and phloem; mechanical behavior) could be based on such a model.