Abstract: Vegetation ecosystem simulation and visualisation are challenging topicsinvolving multidisciplinary aspects. In this paper, we present a newgeneric frame for the simulation of natural phenomena through manageableand interacting models. It focuses on the functional growth of largevegetal ecosystems, showing coherence for scales ranging from theindividual plant to communities and with a particular attention to theeffects of water resource competition between plants.The proposed approach is based on a model of plant growth in interactionwith the environmental conditions. These are deduced from the climaticdata (light, temperature, rainfall) and a model of soil hydrologicalbudget. A set of layers is used to store the water resources and tobuild the interfaces between the environmental data and landscapecomponents: temperature, rain, light, altitude, lakes, plant positions,biomass, cycles, etc. At the plant level, the simulation is performedfor each individual by a structural-functional growth model, interactingwith the plant's environment. Temperature is spatialised, changingaccording to altitude, and thus locally controls plant growth speed. Thecompetition for water is based on a soil hydrological model taking intoaccount rainfalls, water runoff, absorption, diffusion, percolation insoil. So far, the incoming light radiation is not studied in detail andis supposed constant. However, competition for light between plants isdirectly taken into account in the plant growth model.In our implementation, we propose a simple architecture for such asimulator and a simulation scheme to synchronise the water resourceupdating (on a temporal basis) and the plant growth cycles (determinedby the sum of daily temperatures). The visualisation techniques arebased on sets of layers, allowing both morphological and functionallandscape views and providing interesting tools for ecosystem management.The implementation of the proposed frame leads to encouraging resultsthat are presented and illustrate simple academic cases.