疏伐初期對柳杉人工林枯落物和地表枝葉層的影響

Thinning Effects on Litterfall and Litter Layer in Cryptomeria Japonica Plantation during the First Year

林國銓(Kuo-Chuan Lin) ； 杜清澤(Chin-Tzer Duh) ； 黃菊美(Chu-Mei Huang)

《中華林學季刊》 42卷4期 (2009/12) Pp. 595-607

https://doi.org/10.30064/QJCF.200912.0009

摘要

以南投縣巒大事業區36年生柳杉人工林為對象，於該林分經疏伐處理後進行1年枯落物及枝葉層之監測，以瞭解疏伐作業的影響。疏伐作業分2種處理及對照區，包含強度疏伐伐取50%面積之柳杉，中度疏伐伐取25%面積之柳杉。對照區則不疏伐。疏伐後第1年期間枯落物各組成分及總量在處理間和月份間皆有顯著差異。枯落物總量以對照區最高(3.95±2.46 Mg ha^(-1) yr^(-1))，明顯地高於強度疏伐區(1.61±1.18 Mg ha^(-1) yr^(-1)，中度疏伐區介於其間(2.80±1.67 Mg ha^(-1) yr^(-1))。月份間變化，7月有大量發生，9月則為最大量，10月為次大量。台灣森林枯落物季節性的起伏主要受颱風的影響，柳杉人工林颱風月份各處理各枯落物組成分和總枯落物量，皆明顯高於非颱風月份者，其中以柳杉葉和小枝差異最大。其原因可能是柳杉葉和小枝枯死後不立即脫落，在暴雨和強風時才加速脫落。就地表枝葉層生物量而言，其累積總量以中度疏伐區最高(10.64±2.19 Mg ha^(-1))，強度疏伐區次之(8.13±1.92 Mg ha^(-1))，對照區最低(7.81±1.40 Mg ha^(-1))，但統計上無差異，故疏伐作業對地表枝葉層影響不大。就季節而言，對照區和中度疏伐區以秋季和冬季枝葉層量較高，強度疏伐區則以春季和冬季較高，大致上係颱風造成枯落物增加，以致地表枝葉層量上升。

關鍵字

枯落物 ； 枝葉層 ； 疏伐 ； 柳杉人工林 ； 颱風

並列摘要

Litterfall and the litter layer in a 36 year-old Cryptomeria japonica plantation of Luanta circle in Nantou County were monitored for one year after thinning in order to under-stand the thinning treatment effect. The treatments comprise two thinning regimes and an unthinned control. The thinning regimes were strong and medium thinning defined based on 50% and 25% harvested areas, respectively. The amounts of all litter components and total litterfall differed significantly among treatments and months. The largest mean total annual litterfall was at the control stand, 3.95±2.46 Mg ha^(-1) yr^(-1), which was significantly higher than that at the strong thinning stand, 1.61±1.18 Mg ha^(-1) yr^(-1). And the amount at the medium thinning stand was in-between, 2.80±1.67 Mg ha^(-1) yr^(-1). For seasonal dynamics, the massive amount of litterfall occurred in July, then the largest amount was in September, and the second large amount was in October. The monthly litterfall variance of the forest in Taiwan was primarily affected by typhoon. All litter components and total litterfall at the stands during the months with typhoons were significantly higher than those without typhoon. The variance of foliar and twig litter was the highest among them, since dead foliar and twig did not immediately drop, and the litter dropped only due to heavy precipitation and strong wind. The largest total accumulation biomass of litter layer was at the medium thinning stand, 10.64±2.19 Mg ha^(-1). The second was at the strong thinning stand, 8.13±1.92 Mg ha^(-1), then at the control stand, 7.81±1.40 Mg ha^(-1). But no statistically difference was among the stands, which indicates thinning treatment had slight influence on litter layer. The biomass of litter layer of the control and mediate thinning stand were high in autumn and winter, while that of the strong thinning stand was in spring and winter. The increases of litter layer biomass were primary due to increase of litterfall stimulated by typhoon.

並列關鍵字

Litterfall ； Litter layer ； Thinning ； Cryptomeria japonica plantation ； Typhoon