The contribution of tree inventories to the spatial characterisation of the rockfall hazard Rockfall is one of the most frequent natural hazards in mountain areas. The characterisation of rockfall activity in terms of frequency, intensity (energy) and dispersion (run-out distance) is essential for risk management, but is extremely complex due to the diffuse nature of this hazard and the gaps in historical records. In this study we show that trees can be reliable bioindicators to reconstruct rockfall activity. Our method is based on the combination of a systematic mapping of all trees (location, breast height diameter, species) and the complete recording of all visible scars. On an area of one hectare in the municipality of Saint-Guillaume (Vercors massif, French Alps) we recorded 793 trees and 2333 scars. The spatial distribution of the tree species and scars was used to locate the most active source areas and the most important rockfall trajectories and to show the decreasing rockfall activity with increasing distance to the source area and thus also the protective effect of the forest. The approach is particularly valuable in areas where historical records are lacking. It can be used in the future to 1) refine hazard zoning and 2) calibrate rockfall models. Thanks to the recorded tree data, the area could also be used as a marteloscope for practicing silvicultural interventions in the rockfall protection forest.