In mountain areas, natural hazards, such as snow avalanches, landslides and rockfall threat towns, communication routes and people. It is known that forests have a major capacity to dissipate rockfall energy. Forest maintenance or storms can reduce forest’s protective capacity; after such reduction, felled trees can be strategically left on the slopes in order to replace live trees. The efficacy of these devices and their optimal position can be analyzed by developing a numerical model describing the rock-wooden device interaction. To develop a relevant mod- el of these wooden devices when impacted, the research was focused on a rigorous characterization of the fresh wood mechanical properties to recreate the real dynamic response of stems after the impact. Laboratory experiments using a Charpy pendulum assessed the calibration of the numerical model. Experimental results of the impact force and their relation with stems mass and the impact energy level are treated and commented.