柳杉葉和小枝之分解與疏伐關係之探討

Impacts of Thinning on Needle and Twigs Decomposition in Cryptomeria Japonica Plantation

林國銓(Kuo-Chuan Lin) ； 杜清澤(Chin-Tzer Duh) ； 陳明杰(Ming-Chieh Chen) ； 黃菊美(Chu-Mei Huang)

《中華林學季刊》 44卷2期 (2011/06) Pp. 145-156

https://doi.org/10.30064/QJCF.201106.0001

摘要

選取巒大事業區約36年生已完成疏伐的柳杉人工林爲對象，以枝葉包法進行葉和小枝2年的分解研究，以瞭解柳杉林葉和小枝的分解過程以及疏伐對其分解過程的影響。葉和小枝經約2年的分解剩餘重量降至32.3-36.7%。疏伐對葉和小枝重量減少的影響輕微。分解過程可用剩餘重量與時間（天數）以簡單直線迴歸式表示。柳杉的葉和小枝的分解速率較杉木快，介於台灣主要原生闊葉樹之間。分解期間養分的變化，氮濃度呈明顯上升趨勢；鈣與鎂濃度亦會上升；鉀濃度由約3個月起即快速下降；磷濃度則初期上升後保持穩定，最後略微下降；碳氮比則呈現快速下降。至於分解期間養分的剩餘量，氮剩餘量最多，鈣剩餘量次之，鉀剩餘量最少。疏伐對分解期間養分動態變化的影響亦不顯著。在台灣疏伐對分解作用的效應受樹種和生育地的影響，人工林經疏伐後，分解過程會產生不同的結果。

關鍵字

疏伐 ； 枝葉包 ； 分解常數 ； 碳氮比 ； 養分

並列摘要

A 36-year old Cryptomeria japonica plantation in Nuandai circle, which was thinned in 2007, was selected to monitor its decomposition processes of needle and twigs by the litterbag method for a period of two years in order to study the thinning effect on the litter decomposition at the stand. The mass remaining of litter ranged from 32.3 to 36.7% after 2-year decomposition. Since there was no significant difference among treatments, thinning little influence on litter decomposition. During decomposition the relationship of mass remaining and time (days) was determined by using a linear model. The decomposition rates of Cryptomeria japonica needle and twigs were faster than that of Cunninghamia lanceolata and among those of major native broadleaf species. The dynamics of nutrient concentrations during decomposition were wide. Nitrogen concentrations rose significantly, and Ca and Mg rose too. Potassium was lost rapidly after 3-month decomposition. Phosphorus concentrations increased during initial period, then became stable and decreased slightly during final period. Carbon/nitrogen ratio decreased rapidly. For percentage of nutrient remaining mass during decomposition N remaining mass was the highest, then Ca remaining mass, and that of K remaining mass the lowest. Thinning had little influence on nutrient dynamics during decomposition too. Since the effects of thinning on decomposition processes depend mainly upon species and site, the processes were various during decomposition at man-made stand after thinning.

並列關鍵字

Thinning ； Litterbag ； Decay constant ； C/N ratio ； Nutrient