抚育间伐对北美短叶松的生长及材质的影响

以加拿大新布郎斯威克省自然资源与能源部1966年建立的天然林抚育间伐实验基地为研究对象,从3种疏伐强度(1.22 m×1.22 m,1.52 m×1.52 m,2.13 m×2.13 m)的样地和一块控制地中共采伐了154株树,胸径范围10~24 cm,研究抚育间伐(PCT)对北美短叶松的生长及材质的影响。结果表明:随着疏伐强度从1.22 m×1.22 m增加到2.13 m×2.13 m,北美短叶松的死亡率从67.6%下降到32.7%。随着疏伐强度的增加,树干胸径、商品材树干高度和材积、树干削度、树枝直径均显著增加。3种疏伐强度中,只有2.13 m×2.13 m的疏伐强度对树高和树冠的尺寸有显著影响。PCT能增加无节材的长度,但对木材的密度没有显著影响。

Effects of Precommercial Thinning on Tree Growth and Stem Quality in Jack Pine Stands

The impact of precommercial thinning (PCT) on tree growth and stem quality in jack pine was examined. The study was based on a PCT trial established in 1966 in New Brunswick, Canada. Three thinning intensities, 1.22m×1.22m (A), 1.52m×1.52m (B), 2.13m×2.13m (C), and a control stand were studied and a total of 154 sample trees were collected from the trial. Mortality in jack pine stands decreased from 67.6% to 32.7% with increasing PCT intensity from A to C. With increasing thinning intensity, tree diameter, merchantable stem heights and volumes, stem taper, branch diameter, and total lumber volume recovery per tree increased. Yet, only the most intensive thinning intensity (C) showed a significant effect on total tree height and crown development.PCT increased clear stem length, yet had no significant effect on wood density.