Effects of Thinning Practice, High Pruning and Slash Management on Crop Tree and Stand Growth in Young Even-Aged Stands of Planted Silver Birch (Betula pendula Roth)

The objective was to quantify the influence of thinning, high pruning and slash management on crop tree stand growth in young even-aged stands planted silver birch (Betula pendula Roth). This study based two field experiments, aged six eleven years at initiation re-measured after eight years, respectively. Treatments included unthinned control, moderate thinning mainly from below (removing 28–33% standing volume), point favor 300 trees per ha with no elsewhere plot 16–25%), heavy leaving 600 evenly distributed potential future 64–75%). Slash (extraction or retention) applied heavily thinned plots. High removing 30–70% green crown carried out some plots ha, Stand volume increased increasing pre-treatment mean annual increment decreased intensity as compared control. LS-means estimates indicated a reduction for by 14%, 12% (combined pruning) 62%. However, youngest experiment, (without reduced 54%. Combining these results similar experiment Canada, (RedIv%) depending removal (RemV%), both expressed percentage quantified RedIv% = −23.67 + 1.16·RemV% (calibration range: 30–83%). For (large quantities slash), extraction resulted retention. instantaneous numeric average stem diameter thickest (D300) due 3.5, 15–21% 955–11% moderate, subsequent increase D300 during observation period 8.5%, 25 18%, In led unpruned an 30%. pre-selected intensity. plots, increasingly severity; 21% larger 3% pruned trees. As adverse side effect, only were risk windthrow intervention. oldest 95–21% damaged wind.