On the "Stillbergalp", a mountain slope in the Dischma valley south of Davos (Central Alps), a long-term investigation on the technique of reforestation in the zone of the timberline is being carried out as a common effort of the Swiss Forest Experiment Station (ETH, Zurich) and the Swiss Federal Snow and Avalanche Research Institute (Davos). Out of this program, studies on the basic snow conditions in the test area, consisting of the distribution of the snow cover and the avalanche activity, are presented. The combined effects of snow depth variation, dislodgement of snow by avalanches, and mechanical avalanche action characterize six types of sites which are considered to be essential for the development of an afforestation.