- 期刊
- OpenAccess
台灣櫸修枝方法與傷口癒合解析之研究
Pruning Method and Knot Wound Analysis of Taiwan Zelkova (Zelkova serrata Hay.) Plantations
摘要
由於台灣櫸造林木主幹分叉及側枝明顯，嚴重影響主幹品質，因此，於13年生進行不同程度之修枝處理，結果發現修枝後8年，至21年時，林分8年間之胸徑、樹高、斷面積及材積定期年平均生長量，均無顯著差異，經解析各年之生長量發現，2/3樹高修枝高度，在最初1-3年間會造成影響，第4年後，生長已恢復，而1/2樹高修枝處理，對生長影響不明顯。台灣櫸修枝傷口介於1~10 cm間，其中1~6 cm枝徑佔絕大部分約90%。枝徑2 cm以下，傷口可完全癒合，5 cm以上則癒合困難，又台灣櫸修枝方法若採用平切法或中切法，保留一段枝條，皆是不正確之修枝法，前者將造成傷口過大癒合困難，後者枝條枯死形成殘枝，延緩無節材形成之時間，同時造成變色及腐朽。修枝傷口癒合長及癒合年數，主要受殘枝長、傷口直徑及生長速度所影響，本試驗並建立其最適之迴歸關係式，提出台灣櫸最佳之修枝度及方法，以供台灣櫸人工林修枝撫育作業及節材生産預估之重要參據。
並列摘要
Because high forking greatly affecting the formation of the main stem and the wood quality was found in young Taiwan Zelkova plantations, various intensities and methods of pruning were practiced in a 13-yr-old plantation. Results for 8 yr after treatment showed that at the age of 21 yr, there were no significant differences among periodic annual increments in DBH, tree height, breast area, or volume growth. Analysis of the annual in crement showed that growth of trees pruned up to 2/3 of their tree height was affected during the first 1 to 3 yr, but it recovered to the level of unpruned trees by the 4th year. However, there was no effect on the growth of trees pruned up to 1/2 of their tree height. Diameters of the pruning wounds were about 1~10 cm, with most (about 90%) at a size of 1~6 cm. Observations on occlusion after pruning showed that for trees with diameters of pruned wounds smaller than 2 cm, good occlusion occurred. On the other hand, if the diameter of the pruned wounds exceeded 5 cm, healing was difficult. Furthermore, the pruning method, i.e., cutting place of the branch or stem fork, affected wound occlusion. Neither the adapted flush cut nor the retention stud cut were correct pruning methods. The former created a great pruned wound and caused a hard occlusion, while the latter resulted in a stub, which delayed the time required to produce clear wood; moreover, it also caused the wood to discolor or decay. The length of time needed for occlusion of pruned wounds was mainly affected by the length of the branch stub, the diameter of the wound, and the rate of growth. Their best regression relations were established. Suggestions from this study can be used as a useful reference in carrying out optimum pruning intensities and pruning practices and for predicting the clear wood product for Taiwan Zelkova plantations.