修枝對台灣櫸幼林生長及節癒合之研究

Effects of Pruning on the Growth and the Branch Occlusion Tendency of Taiwan Zelkova (Zelkova serrata Hay.) Young Plantations

羅卓振南(Chen-Nan Lo-Cho) ； 鍾旭和(Hsu-Ho Chung) ； 邱志明(Chih-Ming Chiu)

《林業試驗所研究報告季刊》 10卷3期 (1995/09) Pp. 315-323

https://doi.org/10.7075/BTFRI.199509.0315

摘要

台灣櫸幼林木樹幹分叉者甚多，影響主幹形成及林木形質極大。本研究目的即在探討該樹種最適之修枝度及觀測修枝傷口之癒合效應，以期生產高價之無節大徑材。供試林分為5年生台灣櫸人工林，每公頃修枝株數為700株，修枝高度係以林木樹高為標準，將修枝高度定為樹高之(A)1/3；(B)1/2；及(C)完全不做修枝處理等三種。修枝4年後，結果如次：
1．5年生台灣櫸若行修枝，其修枝高度可達樹高之1/2處，而對林分生長並無不良影響。
2．本試驗探討之幼齡林，其樹幹分叉之林木約佔總株數之82%，枝條節徑則界於1.0-8.0cm之間，修枝後4年，傷口癒合約77%，癒合偏低之原因係分叉較多且直徑粗大，不易癒合所致。因此建議台灣櫸於3-4年生間，進行分叉幹修剪。
3．癒合節之觀測結果，節徑在3cm以下者，修枝後3年均能完全癒合，節徑在5cm以上者，則切除作傷口除難以癒合外，尚且產生腐朽陷。顯示台灣櫸修枝應於枝條直徑細小時行之，而節徑已逾5cm以上者，則原則林分不應再予修剪。
4．5年生台灣櫸經修枝後4年，對樹幹完滿程度無顯著之影響。
5．本研究於試驗期間，林木遭天牛及松鼠為害以致枯死者分別約佔總株數之14%及16%。因此，今後台灣櫸之造林須考量天牛及松鼠之為害及防治。

關鍵字

台灣櫸 ； 修枝 ； 節徑 ； 形狀比 ； 癒合

並列摘要

The young Taiwan Zelkova is highly forking which affects its main stem formation as well as its wood quality greatly. Pruning, therefore, is required in tending young zelkova plantations. The purposes of the present research are to study the optimum pruning intensity and the occlusion tendency after pruning. For each hectare of the five-years-old plantations at Compartment No. 4, Pingtung Forest District, Taiwan Forestry Burcau 700selected target trees were treated by (A) pruning up to 1/3 tree height; (B) pruning up to 1/2 tree height; and (C) no pruning. Four years after treatments the effects of pruning were analyzed and recorded as follow:
1. Trees of 5-years-old plantations can be pruned up to 1/2 of their heights without affecting the growth of plantations.
2. Eighty two percent of the trees in all plantations examined showed stem forking. The diameters of these stem forks were about 1.0-8.0cm. Four years after pruning the percentage of occlusion was only about 77% due to the large number and size of the forks pruned. It is, therefore, suggested that the zelkova plantations be pruned at the age of 3-4.
3. Observations on occlusion after pruning showed that if the forks being removed were smaller than 3cm in diameter good occlusion occurred. On the other hand, if forks with diameter greater than 5cm were pruned occlusion failed; and, as a result, wood decay occurred. These observations suggest that pruning can be practiced only when the diameters of trees are less than 5cm; and, when exceeded, no pruning treatment should be excersised on zelkova plantations.
4. Four years after pruning of the 5-years-old zelkova plantions no significant improvement on the stem form and, hence, the roundness was found on pruned trees.
5. During the four years experiment period the plantations were damaged by longicorn beetles and squirrels witch caused a mortality, in terms of number of trees damaged, of 14% and 16% respectively. The potential damages caused by these pests should be taken into account in establishing Taiwan Zelkova plantations in the future.

並列關鍵字

Zelkova serrata Hay. ； pruning ； branch diameter ； form quotient ； occlusion