Hochlagenaufforstungen in Lawinenverbauungen im Berner Oberland

Abstract

Since the 1950s, high altitude regeneration projects have been carried out in the avalanche control areas of the Bernese Oberland, using site-appropriate seedlings of domestic provenance from the cantonal nurseries. These plantations are intended to prevent, in the medium to long term, the start of avalanches. On the one hand, the article presents an analysis of the measures taken since 1995, and the field measurements made in the high altitude plantation at Schwanderort (1730–1780 m) above Brienz. This provides information on the development of young Spruce under extreme external conditions. On the other hand, the article investigates from what age the regeneration can provide avalanche protection functions, based on the growth characteristics of 112 trees of different ages, from 24 avalanche protection projects. Site conditions at high altitude are much more extreme and vary more from year to year than at lower altitude. Nineteen years after the plantation at Schwanderort, 60% of the Spruce are still alive; over this period, their average height has increased from 19 cm to 152 cm. Because of the short vegetative period, their height growth takes place between 20 June and end of July, and is stopped or strongly reduced when average temperatures are below 10°C. Analysis shows that at the upper forest limit, one must wait 45–50 years before regeneration can fulfil its avalanche protection function.