Wounding experiments, imitating the impact of geomorphic processes such as rock fall, were performed on Larix decidua Mill. and Picea abies (L.) Karst., before the beginning and at the end of the growing season. This was done to evaluate the timing and spread of traumatic rows of resin ducts (TDs) as a result of wounding during dormancy, when most mass movements occur. All treatments were successful in inducing TDs. However, a high inter- and intra-species variability concerning the timing and position of the TDs was noted. In larch, TDs were formed as first cells after wounding (immediate reaction) only in the vicinity of the wound. In contrast, none of the spruce trees exhibited immediate reactions. Neither larch nor spruce formed continuous TDs around the stem. TDs in larch were more extensive if, in addition, stems were bent before the growing season. In contrast, spruce showed this reaction when bent at the end of the growing season. The results indicate that the varying lengths of the growing seasons at different geographical locations need to be taken into account before an immediate wound reaction can be clearly defined, if an increase of the reliability and accuracy of process reconstructions is aimed for.