Effect of Planting Density on Knot Attributes and Branch Occlusion of Betula alnoides under Natural Pruning inSouthern China

Forests

Johanna Schuler¹  Ji Zeng²  Wenfu Guo²  Junjie Guo³  Jie Zeng³  Zhigang Zhao³  Chunsheng Wang³  Sebastian Hein⁴ 

[1] Chair of Forest Growth, Albert-Ludwigs-University, 79106 Freiburg, Germany;Experimental Center of Tropical Forestry, Chinese Academy of Forestry, Pingxiang,Guangxi 536000, China;Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong,Guangzhou 510520, China;University of Applied Forest Sciences, Schadenweilerhof, 72108 Rottenburg, Germany;

关键词: Betula alnoides;    spacing;    self-pruning;    branch occlusion;    knottiness;    mixed models;    wood quality;   

DOI  :  10.3390/f6041343

来源: DOAJ

【 摘 要 】

Knot-related defects are the major cause of timber quality degradation, and diminishing this kind of defects is an important issue in forest management. For the purpose of clear-wood production, knot attributes and branch occlusion of Betula alnoides under natural pruning were investigated in a 14-year-old experimental plantation with five planting densities ranging from 500 to 3333 stems per hectare in southern China, and a total of1325 occluded branches from 30 trees were sampled and dissected. The mean occluded branch diameter (OBD), radius of knots and branch insertion angle (IA) decreased significantly with increasing planting density. Planting with high stocking density significantly reduced the frequency of thick occluded branches (diameter ≥ 20 mm) while increasing the frequency of small ones (diameter < 10 mm). Branch occlusion time (OT) also tended to increase with decreasing planting density. The results of generalized linear mixed models showed that OBD was the major factor influencing OT, radius of dead portion of knot (RDP), total radius of knot (TRK) and IA. In addition, OT was positively correlated with RDP but negatively correlated with stem diameter growth rate during branch occlusion (SDGR). Silvicultural strategies with appropriate planting density for large-diameter clear-wood production of B. alnoides were discussed.

【 授权许可】

Unknown