Université de Fribourg

Reactions and energy absorption of trees subject to rockfall: a detailed assessment using a new experimental method

Lundström, Tor ; Jonsson, Martin J. ; Volkwein, Axel ; Stoffel, Markus

In: Tree Physiology, 2009/29//doi:10.1093/treephys/tpn030

A new method for investigating the detailed reaction and the energy absorption of trees during a rock impact was developed and applied to 15 subalpine Norway spruce (Picea abies L. Karst) trees. A wedge-shaped trolley, guided by prestressed steel wires, was mounted on a forested slope to simulate a falling rock. The trolley accelerates down the wires and hits a tree at a preselected stem height...

Université de Fribourg

The root-soil system of Norway spruce subjected to turning moment: resistance as a function of rotation

Lundström, Tor ; Jonsson, Martin J. ; Kalberer, M.

In: Plant and Soil, 2007, vol. 300, no. 1-2, p. 35-49

The reactions of trees to wind, rockfall, and snow and debris flow depend largely on how strong and deformable their anchorage in the soil is. Here, the resistive turning moment M of the root–soil system as a function of the rotation ϕ at the stem base plays the major role. M(ϕ) describes the behavior of the root– soil system when subject to rotational moment,...

Université de Fribourg

State of the art in rockfall – forest interactions

Dorren, Luuk ; Berger, Frédéric ; Jonsson, Martin J. ; Krautblatter, Michael ; Mölk, Michael ; Stoffel, Markus ; Wehrli, André

In: Schweizerische Zeitschrift fur Forstwesen, 2007, vol. 158, no. 6, p. 128-141

To effectively prevent rockfall related disasters below forested slopes, silvicultural, eco-engineering, civil engineering or mixed techniques can be used. To do this in a cost-efficient manner it is necessary to know the following: 1) where rockfall events occur and which magnitudes are likely, 2) to what extent the forest reduces the run-out distances, the jump heights and the energies of rocks...