The aim of this research is to achieve forest planning of some public forests in the south of Belgium. The first step is the collecting of informations dealing with history, ecological and economic environment, forestry and various descriptions of the wooded area, environmental constraints (relative to water or soil protection). The synthesis of these informations allows to determine realistic objectives which ensure the balance between all the functions assigned to forest. Finally, the measures to achieve these objectives are defined. A GIS is used to map forest boundaries and to calculate the extent of the constraints (water or soil protection, e.g.) in each compartment.