六龜台灣杉人工林枯落物之動態變化

Litterfall Dynamics in Taiwania Plantations of the Liukuei Experimental Forest in Southern Taiwan

林國銓(Kuo-Chuan Lin) ； 陳永修(Yun-Hsiu Chen) ； 杜清澤(Chin-Tzer Duh) ； 黃菊美(Chu-Mei Huang)

《中華林學季刊》 41卷3期 (2008/09) Pp. 351-363

https://doi.org/10.30064/QJCF.200809.0005

摘要

以林業試驗所六龜試驗林台灣杉20和27年生人工林為對象，並區分為疏伐處理和未疏伐兩種，測定其枯落物的動態變化。經3年2個月監測，20年生林分未疏伐與疏伐林分平均枯落物量分別為5.74和5.59 Mg ha^(-1) yr^(-1)，27年生林分未疏伐與疏伐林分則為3.56和4.43Mg ha^(-1) yr^(-1)。各林分枯落物量年度間變化很大。年度間的差異主要由颱風造成，颱風干擾的年度枯落物量較高。枯落物中葉和小枝所佔比例最高為75.9~90.3%，枝條次之，佔4.8~16.4%，非台灣杉植體和其它物質最低。台灣杉人工林枯落物量略高於或等於台灣其它針葉人工林，與台灣天然闊葉林相近或較低。枯落物季節性變化極明顯，年度間僅5~7月有一高峰期，主要受颱風和降水量影響，使月枯落物量明顯增加，且造成枝條大量脫落，此與台灣天然闊葉林常形成2個高峰不同。枯落物量和降水量呈正相關，與台灣天然闊葉林相似。本研究台灣杉人工林其枯落物量不受疏伐處理的影響，主要係疏伐經過6年後，樹冠大致已恢復，不影響枯落物的產生。

關鍵字

枯落物 ； 疏伐 ； 台灣杉人工林 ； 颱風 ； 樹齡

並列摘要

The litterfall dynamics in four Taiwania (Taiwania cryptomerioides Hayata) plantations with two age classes and thinning treatment in the Liukuei experiment forest of Taiwan Forestry Research Institute were investigated for three years and two months. The mean annual litterfall were 5.74 and 5.59 Mg ha^(-1) yr^(-1) in the 20-yr-old plantations for the control and thinning treatment, respectively, while there were 3.56 and 4.43 Mg ha^(-1) yr^(-1) litterfall in the 27-yr-old plantations for the control and thinning treatment, respectively. The litterfall amount differed widely between ages and among years. The litterfall amount in the 20-yr-old stands was higher than that in the 27-yr-old stands. Typhoon, which causes massive amount of litterfall, is the main factor affecting annual variances. The foliar and twig litter was 75.9~90.3% of total litterfall and the highest percentage among the components. The branch litter was the second, 4.8~16.4% of total, and tissues of other species and other material were the lowest. The litterfall amount of the stands was slightly higher than or equal to these of other coniferous plantations and closed to or lower than these of natural broadleaf forests in Taiwan. The variances of mean monthly litterfall were extremely large, and the mean monthly litterfall showed a peak period only from May to July in each year. The increase of litterfall was due to typhoon and heavy precipitation, which stimulated a large amount of branch litter too. The one-peak phenomenon differs from these of natural broadleaf forests in Taiwan with two-peaks in a year. The litterfall amount positively related to precipitation, and the relation is similar to that of natural broadleaf forest in Taiwan. Meanwhile thinning did not affect litterfall, because the canopy was almost recovered in six years after thinning.

並列關鍵字

Litterfall ； Thinning ； Taiwania plantation ； Typhoon ； Tree age