疏伐與修枝對紅檜人工林生長之效應

Effect of Thinning and Pruning on the Growth of Taiwan Red Cypress (Chamaecyparis formosana Matsum) Plantations

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

《台灣林業科學》 12卷2期 (1997/06) Pp. 145-153

https://doi.org/10.7075/TJFS.199706.0145

摘要

紅檜人工林應以長伐期為經營導向，因此中間撫育之施行，需以生長高品質大徑材為目標。本研究乃就南投林管處阿里山事業區第104林班14年生紅檜人工林施行疏伐及修枝試驗。疏伐度係以每公頃胸高斷面積保留量為基準，以下層疏伐之方式選定疏伐木，計分為二種；(A)保留25平方公尺/ha；(B)對照組。不同修枝度係以林木樹高為標準，將修枝高度定為樹高之(a)1/2；(b)2/3；(c)對照區等三種。處理後5年，結果如次：
1．14年生紅檜人工林施行疏伐，以每公頃保留木胸高斷面積25平方公尺，可提高林分材積生長量，此時修枝高度則以不超逾樹高之1/2處為宜。
2．經修枝之供試林分，其樹幹形狀較完滿，而未修枝之林分，其樹幹形狀則較尖削。修枝確有助於提高紅檜林分樹幹之完滿度，增加材積生長之效果。
3．本研究14年生紅檜人工林，每公尺樹幹著生之枝條約有11枝，節徑分布界於0.2～8.5 cm之間，修枝後5年，傷口痊癒者約佔73%，癒合率較低之原因，係枝條直徑較大，傷口不易癒合所致，因此，紅檜之修枝撫育，應於幼齡時期枝條直徑尚為細小時施行切除為宜。
4．疏伐後之保留木必須同時施行修枝，否則將因生長空間之增大，造成分叉幹或側枝徒長。

關鍵字

紅檜 ； 疏伐 ； 修枝 ； 形率 ； 癒合

並列摘要

The present study was carried out in a 14-y-old red cypress (Chamaecyparis formosana Matsum) plantation located at No. 104 Compartment of AliShan Working Circle. A thinning-from-below approach was used in the experiment in which a plantation was either left unthinned (the control) or thinned to the extent of retaining 25 m^2/ha of absolute basal area (BA). In the pruning experiment 3 treatments were applied: (a) pruning up to 1/2 tree height; (b) pruning up to 2/3 tree height and (c) no pruning (the control). After 5-y, the effects of these treatments on the growth of plantations can be summarized as follows:
1. For the 14-y-old red cypress plantations of AliShan Working Circle, a thinning regime of retaining 25 m^2/ha. BA has resulted in increasing the volume growth. Pruning up to 1/2 tree height was also found to be beneficial in improving plantation growth.
2. Thus trees of pruned plantations show less tapering than do those of unpruned ones. Pruning, improves the roundness of trees as well as increases the volume growth of red cypress plantations.
3. About 11 branches/tree were recorded for all trees examined; the diameters of these branches were about 0.2-8.5 cm, Five years after pruning, the percentage of wound occlusion was only about 73%. The low percentage of occlusion was due to the existence of large branches and the difficulty of ocduding the wounds resulting from pruning these branches. Pruning of red cypress, therefore, should be carried out when plantations are young and tree branches are small.
4. Thinning of plantations results in increased spacing which, in turn, enhances branching. Trees retained after thinning, therefore, should be pruned to prevent branching and/or forking.

並列關鍵字

Chamaecyparis formosana Matsum ； thinning ； pruning ； form quotient ； occlusion