CAJ | 학술논문

柳杉人工林于24年生时,经不同带宽之行列疏伐处理后,疏伐带栽植扁柏、红桧、台湾杉、香杉4种林木,历经21 a后,目前之成活率,不同带宽成活率差异不显著；但树种间成活率差异显著,以台湾杉最高59%,香杉最低31%。而其胸径和树高之生长,不同疏伐带间部分树种之胸径、树高生长差异不显著；但树种间胸径、树高生长差异极显著。保留带之柳杉胸径、树高之生长明显大于对照区,而材积现存量则对照区仍大于疏伐区。在定期平均生长方面,胸径生长在疏伐13 a后,疏伐效果已减缓；而材积生长则在疏伐7 a后即明显超越对照区。行列疏伐保留带之留存木,在疏伐后6 a间,有较严重之风害,因此建议未来进行疏伐时,留存带应该扩大宽度,建议宽度在20 m以上,以减少风害。在林下地被植物调查方面,全区共调查到97种植物,Shannon 多样性指数达到1.78,而Simpson多样性指数则为0.66。在不同的疏伐处理下,保留带与对照区的种类丰富度均低于疏伐处理后的区域,反映出疏伐作业会造成不同的林下环境条件,进而影响地被植物的组成多样性。在林下天然更新树木的调查成果方面,全区共调查到66种、2010株树木,平均植株密度为941株蛐hm2,Shannon多样性指数达到2.92,Simpson多样性指数则为0.89。在不同的疏伐处理下,天然更新树木的组成多样性已接近显著差异。天然更新树木的数量上,保留带与对照区的林木密度均显著高于疏伐区域,反映出过去的各项森林施业过程(疏伐、下木栽植、抚育等)会实质地影响到林木的天然更新状态。
류삼인공림우24년생시,경불동대관지행렬소벌처리후,소벌대재식편백、홍회、태만삼、향삼4충림목,력경21 a후,목전지성활솔,불동대관성활솔차이불현저；단수충간성활솔차이현저,이태만삼최고59%,향삼최저31%。이기흉경화수고지생장,불동소벌대간부분수충지흉경、수고생장차이불현저；단수충간흉경、수고생장차이겁현저。보류대지류삼흉경、수고지생장명현대우대조구,이재적현존량칙대조구잉대우소벌구。재정기평균생장방면,흉경생장재소벌13 a후,소벌효과이감완；이재적생장칙재소벌7 a후즉명현초월대조구。행렬소벌보류대지류존목,재소벌후6 a간,유교엄중지풍해,인차건의미래진행소벌시,류존대응해확대관도,건의관도재20 m이상,이감소풍해。재림하지피식물조사방면,전구공조사도97충식물,Shannon 다양성지수체도1.78,이Simpson다양성지수칙위0.66。재불동적소벌처리하,보류대여대조구적충류봉부도균저우소벌처리후적구역,반영출소벌작업회조성불동적림하배경조건,진이영향지피식물적조성다양성。재림하천연경신수목적조사성과방면,전구공조사도66충、2010주수목,평균식주밀도위941주곡hm2,Shannon다양성지수체도2.92,Simpson다양성지수칙위0.89。재불동적소벌처리하,천연경신수목적조성다양성이접근현저차이。천연경신수목적수량상,보류대여대조구적림목밀도균현저고우소벌구역,반영출과거적각항삼림시업과정(소벌、하목재식、무육등)회실질지영향도림목적천연경신상태。
This study aims to investigate a Cryptomeria ( Cryptomeria japonica ) plantation which was row-thinned with different thinning regimes at age 24 and under-planted with 4 species:Taiwan yellow false-cypress ( Chamaecyparis obtusa var. formosana) , Taiwan red false-cypress ( Chamaecyparis formosensis) , Luanta-fir ( Cunninghamia konishii ) and Taiwania ( Taiwania cryptomerioides ) in the thinned areas. After 21 years, the survival rates of under-planting trees revealed significant differences in different planting species ( ranging from 59% in Taiwania to 31% in Luanta-fir) , but not so in different thinning treatments. The DBH and height growths of the under-planting trees also showed significant inter-specific differences, however the effect of different thinning treatments was not significant. The DBH and height growth of Cryptomeria in the reserve strips were significantly higher than that in the control area. However, the volume in the control area was still larger than that in the thinned areas. We also observed a decrease of thinning effect on the periodic annual increments of diameter 13 years after thinning. The volume growth in the thinned areas obviously exceeded that in the control area 7 years after thinning. Besides, due to the serious wind damages occurring in the retained Cryptomeria trees 6 years after thinning, we recommend adopting broader retaining strips ( >20 m) in thinning operations to prevent wind damages. In the investigation of ground-layer vegetation, 97 plant species were recorded, with the Shannon index of diversity reaching 1.78 and the Simpson index of diversity reaching 0.66 . The species richness was averagely lower in the retaining strips and control area than in the thinned areas, suggesting that different thinning treatments would create different environmental conditions in the understory and thus affect the composition and diversity of ground-layer vegetation. In the investigation of natural regeneration trees, 66 species and 2 010 trees ( 941 trees/hm2 , averagely ) were recorded, with the Shannon index of diversity reaching 2.92 and the Simpson index of diversity reaching 0.89 . The diversity of natural regeneration trees in different thinning treatments revealed marginally significant differences, while the tree densities showed significant increases in the retaining strips and control area. These results suggest that the previous forest operations ( thinning, under-planting, and tending etc. ) would substantially affect natural regeneration in the under-story.