ZLV Online

Abstract

Growing Norway spruce at relatively warmer and drier conditions poses a threat of its die-off. Despite recent focus of silviculture on conversion of tree species composition, foresters still have to cope with existence of monospecific young spruce stands. Four thinning experiments were established at lower altitudes to investigate a response of stand characteristics to early thinning. Experimental thinning accelerated diameter increment of spruce crop trees significantly. Thinning also slowed pace of the slenderness ratio development thus impacting on the h/d values positively. Live crowns got short more slowly following thinning compared to control. Spruce stands at lower altitudes must be thinned as early as possible when mean height of dominant trees achieves 5 m. Given the risk of growing spruce at lower sites, all suitable tree species should be left on site. Spruce should be no longer grown in monospecific stand over the whole rotation, however silviculture measures should focus on maintenance of its share in future species composition.