ZLV Online

Abstrakt

Wind and snow are the most important abiotic agents, which negatively affect Norway spruce forest stands in Europe. To prevent the spruce stands from damage, silvicultural measures were verified using data from 15 long-term thinning experiments. Thinning began at the age of 38–67 years (older stands, OS) and 15–20 years (younger stands, YS). These two groups differ also in terms of thinning intensity, i.e. light thinning in OS and heavy thinning in YS experiments. Initial densities in OS stands were about 10 thousand plants.ha-1, while the densities in YS stands were about 2.5–3.5 thousand plants.ha-1. It can be concluded that thinning affected positively DBH and slenderness ratio of both mean stem and dominant trees. As for YS stands, the response to thinning was greater. The YS stands also showed longer live crown and higher crown length/stem height ratio (%) compared to unthinned control plots. Heavy early thinning in Norway spruce stands is recommended to stabilize them against abiotic agents. The stabilized spruce stands are then prepared to start species composition conversion towards more stable mixtures with other species (e.g. broadleaves, European larch or Douglas-fir).