The challenge when regarding the forest stand as a protection barrier against rockfall is to assess and predict its protection effect. To investigate this, full-scale impact tests, which simulated the interaction between a single tree and an impacting mass (trolley), were done in its natural environment. It was shown that the complex interaction between the simulated rock and a single Norway spruce tree (Picea abies (L.) Karst.) can be modelled with finite elements. By performing parameter studies using the developed model, the energy absorption capacity E_cap of a single Norway spruce tree as a function of diameter at breast height DBH and the position of the flying rock in terms of impact height H_imp, eccentricity χ, and impact angle α_imp could be calculated.