Trees and rockfalls: use of slash as rockfall protection on forested slopes

Overview & Synopsis

In mountainous regions forested slopes play an important protective role against rockfalls. Complementary with the classical researches on the dissipative effect of standing and living trees, this research program studies the protective capacity of tree stumps and log against snow avalanches and rockfalls. In Austria, the felling technique Alpi has been developed. It allows a specialised lumberjack to create small rockfall barriers using one or two tree stems anchored on high tree stumps. Lying tree stems can be then used to increase efficiently the roughness of the soil and so to limit or avoid triggering and propagation falling rocks. But, due to the wood decay, the efficiency of such protective works is decreasing with time. The main objectives of this research program are to quantify the efficiency of rockfall protection structures depending on their characteristics (stump and stems density, position on the slope, tree species, etc.), and to evaluate their resistance over time taking into account the decomposition of wood. This study is part of the European Interreg IV Alpine Space project "MANFRED".