Silvotehnica molidișurilor artificiale, pure și tinere, din România: un exemplu

The paper shows the results of a small-scale R&D project on early silviculture of Norway spruce, carried out in a pure plantation of 0.4 ha, 2 x 1 m (5,000 plants ha-1), established in 2001. In 2009, following the application of an access pruning on all stand trees, 60 ”potential” final crop trees were selected throughout the stand, based on the vigour-quality-distribution criteria, being subsequently pruned up to 4-4.5 m. In the same year, two plots, each of 300 sq.m, were established and a mixed and heavy cleaning-respacing was carried out classically (typical to stand silviculture, in plot 1) or dynamically (as in case of crop tree silviculture, in plot 2). A classical cleaning-respacing (mean canopy cover 80% after intervention) was also performed at stand level, leaving the ”potential” final crop trees in a free-growth state at the crown level. A mixed thinning, similar to the intervention in 2009, was carried out at both plot and stand level in 2013, with the remaining density of 1,167 trees ha-1 (plot 2) and 1,567 trees ha-1 (plot 1) and basal area of 20.67 sq.m ha-1 (plot 2) and 23.47 sq.m ha-1 (plot 1). In 2020, the mean arithmetic diameter and mean quadratic diameter of trees in plot 2 and ”potential” final crop trees reached 20 cm. Out of these trees, over 50% are at least 20 cm in diameter. The basal area in plots 1 and 2 is over 35 sq.m ha-1 so a new thinning is due to be carried out in 2020, to reduce the basal area under the critical value of 30 sq.m ha-1. Mean height reached 15 m in 2020, and the slenderness (stability) index has grown significantly only in plot 1, reaching the value of 85. The R&D project showed clearly the possibility of producing Norway spruce trees of 20 cm d.b.h. in 20 years, by using intensive crop tree silviculture started earlier, during the thicket development stage.