To fully understand the protection effect of the forest, the single tree behaviour must be accurately known. However, trees are complex biomechanical systems especially regarding their interactions with rock boulders. A single tree dissipates energy during a rock impact in several different ways: rotation and translation of the root system, deformation and oscillation of the tree stem and local penetration of the rock at the impact location (Foetzki et al. 2004; Brauner et al. 2005; Dorren and Berger 2005). The main objectives of this work are therefore to assess and predict the protection capacity of a forest stand against rockfalls using the simulated behaviour of a single tree. A Finite Element model usable for practitioners was developed that can be used to predict the rock-tree interaction during a rock impact for a Norway spruce (Picea abies (L.) Karst.) tree.