Die Bedeutung der winterlichen Schneedecke für junge Fichten im Gebirgswald: Ergebnisse aus dem Lusiwald bei Davos

Abstract

Besides the environmental conditions during the growing season, the winter snow cover is expected to have crucial effects on the development and survival of young spruce trees in subalpine forests. To identify crucial micro site conditions for the regeneration of subalpine spruce forests, an experiment was set up in the Lusiwald forest near Davos in 1989. Until 1996, 84 groups of 16 11-years-old spruce trees were yearly monitored in terms of tree height, growth form, browsing by wild ungulates, infestation by snow mold and survival. In winter, snow depth was measured and snow melt was mapped in spring. The winter snow conditions were significantly different between forest openings and the stand. The snow was on average 20% deeper in the forest openings, leading to a retarded snow melt. As a consequence, infestation by snow mold was more frequent in the openings (20.4%) than in the stand (15.4%). In contrast, the reduced snow cover and earlier melt in the stand led to increased browsing by wild ungulates (8%; opening: 5.4%). Independent of the micro site, a fourth of all tree groups showed curved stem bases. In the openings, trees grew higher (53.8%; stand: 45.3%), whereas their survival was reduced (88.3%; stand: 93.1%), probably due to snow mold. The experiment in the Lusiwald shows, that the condition of spruce trees is direct and indirect decisively influenced by winter snow conditions.