A voxel cellular automata for modelling opportunistic tree root systems in agroforestry

Correspondance: dupraz@supagro.inra.frInternational audienceThe simplistic representation of the shape and density of tree roots in agroforestry systems was identified as a major weakness of many models. A subtler means of simulation would require that the tree must colonise the most favourable areas of soil, taking account of the influence that neighbouring crops and trees exert on the development of its root system. A universal root growth module is suggested, which combines a degree of genetic control and the local pedo-climatic conditions affecting root growth. This module adopts a 3-D voxel automata approach to modelling the fine roots at the day time-step. Coarse root topology is deduced from the colonisation patterns predicted by the fine root automata. This module allows an easy way of modelling management decisions such as root pruning or various tree-crop distances. The module is incorporated in the HiSAFE model. It aims at providing a realistic tree root growth modelling in a 3- dimensional heterogeneous soil. It should be able to model the opportunistic growth of tree root systems, reacting to local soil conditions for root proliferation, colonisation and death. Split-root container grown trees provided data for a first calibration of the module. This research was carried out as part of the SAFE (Silvoarable Agroforestry for Europe) collaborative research project. SAFE is funded by the EU under its Quality of Life programme, contract number QLF5-CT-2001-00560, and the support is gratefully acknowledge