Development of spruce (Picea abies [L.] Karst.) target (crop) trees in pole-stage stand with different initial spacing and tending regime

This paper presents findings of a twenty-year investigation of silviculture-production in a 40-year-old afforested spruce pole-stage stand located in a mountain region. The stand was established by four different spacing models: (i) 1.5 × 1.0 m, (ii) 2.5 × 1.0 m, (iii) 2.5 × 1.5 m, and (iv) 2.5 × 2.5 m. Three alternatives were studied for each of these spacing models. These were: (i) geometrical (line) thinning, (ii) selective thinning and (iii) no tending. During the period of our research the above-mentioned stand was affected twice by a snow-break disaster. Promising and target trees in the stand were marked and selected at the beginning of the study. The development of the above-mentioned categories of trees was analysed in relation to the initial spacing of the stand, as well as to the method of tending. Based on the 20-year research period, we conclude that the most favourable results were obtained on plots that were established at a wider initial spacing and managed by selective thinning as opposed to the denser ones tended by geometrical thinning or without any tending.