Assessing the vertical distribution and visibility of rockfall scars in trees
Stoffel, M.(Universite de Fribourg, Fribourg (Switzerland). Departement des Geosciences/Geographie)
Rockfall generally consists of individual rocks and boulders moving down slope in a falling, bouncing or rolling motion. As a result, impacts on trees can occur almost anywhere between ground level and several meters above. The present paper therefore focuses on the vertical distribution and the visibility of scars on stem surfaces. Three adult trees from the Bannwald of Altdorf were sawn into 307 cross-sections in order to determine impact heights and to assess the number of hidden scars no longer visible from outside. Results indicate that scars can be observed at heights of up to nine meters or more. Depending on the tree species selected, «blurred evidence» accounted for 16 to 49%. We can suppose that bark properties might influence the blurring of scars.
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