This paper describes a simulation environment, called Cormas, that relies on multi-agent systems and has been achived in SmallTalk, using VisualWorks software. Such a simulation tool may prove useful to better understand the complex interactions between natural and social dynamics when studying renewable resource management. The general principles of the Cormas platform are first presented, then the implementation is described. Two models built with Cormas allow to illustrate the use and the genericity of this tool.