柳杉人工林不同疏伐強度對原生樹種更新之影響

The Effect of Different Thinning Intensity on Regeneration of Native Tree Species in Cryptomeria japonica Plantation Forest

孫義方(I-Fang Sun) ； 黃正良(Jeen-Lian Hwong) ； 陳明杰(Ming-Chieh Chen) ； 曹崇銘(Tsung-Ming Tsao) ； 黃志堅(Chih-Chien Huang) ； 傅昭憲(Jhao-Sian Fu) ； 黃騰禾(Teng-He Huang)

《中華林學季刊》 45卷1期 (2012/03) Pp. 13-29

https://doi.org/10.30064/QJCF.201203.0002

摘要

疏伐可以造成森林結構及微環境的立即變化，有利於種子發芽及幼苗生長，對於樹種更新的研究非常重要。本研究目的是探討柳杉人工林不同疏伐強度對原生樹種更新及復育的影響，藉以瞭解不同原生樹種更新之瓶頸及困境，並進一步研究種子雨在空間及時間上分布狀況及變異情形。研究地點位於台灣林務局南投林區管理處巒大事業區74、75及76林班，於2007年6至9月進行疏伐作業，總共12個試驗樣區，每個樣區面積一公頃，分成未疏伐（0%）、疏伐25%及50%面積三種樣區、並各有四重複。疏伐前在人工林永久樣區內設置108個種子網及324個小苗樣區，並且收集植物物種、種子產量及小苗數量的基本資料。自2007年11月到2009年4月為止總共收集35次種子雨，合計收集木本種子16種4,683顆，其中以賊仔樹的數量佔34.9％最多。各樣區收集的種子數量，依大小順序分別為疏伐面積0％樣區（2,831顆）＞疏伐面積25％樣區（1,290顆）＞疏伐面積50％樣區（562顆）。疏伐後22個月進行小苗調查發現，出現在樣區內的小苗總數量變化不大。但是，各樣區物種增加總數分別為疏伐面積50％樣區（47種）＞疏伐面積25％樣區（14種）＞疏伐面積0％樣區（5種）。疏伐後隨著時間加長，到達樣區的原生樹種小苗種類也越來越多。疏伐方式創造了適合原生樹種更新的環境條件，增進柳杉人工林的生物多樣性。

關鍵字

人工林 ； 疏伐 ； 種子網 ； 原生樹種

並列摘要

Thinning will immediately create changes in forest structure and microenvironment of a plantation forest for suitable conditions for seed germination and seedling establishment. Therefore, this is a favorable change for understanding the regeneration of native tree species after thinning. The purposes of this study are to assess the effect of different thinning intensity and to understand the difficults and bottlenecks during the regeneration processes of native tree species. We also evaluated dispersal limitation and recruitment limitation by different thinning intensity. The study site locates at No. 74, 75, and 76 compartments in NanDai Working Circle of Nantou Forest District Office, Taiwan Forestry Bureau. Twelve 1-ha plots were established in the Cryptomeria japonica plantation forest. Thinning treatments included control (0%), 25% thinning, and 50% thinning from July to September, 2007, which treatment has four replications. 108 Seed traps and 324 seedling plots were established in the plot for tracking seed and seedling dynamics. According to 35 seed rain censuses through November 2007 to April 2009, a total of 4,683 seeds were collected and identified to 16 species. The most abundant species was Tetradium glabrifolium (34.9%). Number of seeds arrival showed the order as follows: 0% thinning (2,831 seeds) ＞ 25% thinning (1,290 seeds) ＞ 50% thinning (562 seeds). The results of seedling survey after 22 months of thinning showed that numbers of seedlings were similar before and after thinning. However, the species richness showed the order as follows: 50% thinning (47 species) ＞ 25% thinning (14 species) ＞ 0% thinning (5 species). The richness and abundance of native tree species were significant increased after thinning. Therefore, thinning events can create regeneration niches and providing suitable environmental conditions for native tree species. Our results suggest that thinning is a good strategy for increasing biodiversity in Cryptomeria japonica plantation forest.

並列關鍵字

Plantation forest ； Thinning ； Seed trap ； Native tree species