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上谷關植被樣帶變遷之研究（1990年～2001年）
The Research Of The Succession Of Vegetation Transects At Upper Kukuan
摘要
本研究於1990年，在上谷關的臺電谷關訓練中心所屬之一處山坡地，設置2條長方形樣帶（樣帶A及樣帶B），進行調査離地0.5公尺處，直徑大於1公分之每木直徑、樹高、種類，予以編號、登錄相對位置，並於2001年重新調查，以探討次生林之變遷，以及再次干擾等影響。該調查之兩樣帶設於鄰近區域，樣帶A面積為0.09公頃，樣帶B為0.21公頃，但兩樣帶1990年之IS_(MO)相似性係數只有28.0 % ，顯示其乃不同植物社會組成之林分。此外，樣帶B於1996年賀伯颱風之際，曾受土石流干擾。1990年樣帶A底面積優勢為香楠、楓香、山黃麻，但於2001年時，非耐陰性樹種山黃麻之底面積減少，且存有較為耐遮陰的物種之重要值提高，例如：九節木、玉山紫金牛，導致兩調查年度的IS_(MO)相似性係數，只為68.8 %。樣帶A於11年後，底面積減少（4.5 m^2變為4.0 m^2）、密度則幾乎相同（237株變為238株），而死亡率為32.9 % ，新增率為33.3 %。樣帶B於2001年，物種優勢組成和未受干擾前，亦即1990年的調查紀錄相似，皆為山黃麻及相思樹。比較兩調査年度之IS_(MO)相似性係數達82.5%，組成與結構相似，但其變動實為原有個體大量死亡，2001年所見個體多為新加入者。植株個體有70.8 %死亡，新增率達178.8%，相對較樣帶A為高，顯示受到土石流大規模干擾的樣帶B植被，可於短時間內自我更新，而且，樣帶B於1990年之際，亦處於干擾過後狀態，始令其組成相似。本樣帶之次生植被結構為：樹冠層，約10-15公尺，以相思樹、山黃麻為主；次樹冠層，約4-6公尺，以石朴、白匏子、構樹及小葉桑為主；而灌木層，約為2～3公尺，組成有長梗紫麻、杜虹花、牛奶榕及臺灣山桂花等。綜合言之，上谷關兩樣帶11年後之變動大，但兩樣帶變遷各有不同。樣帶A之組成及結構已有轉變，可能為走向演替的另一階段，或只是短暫循環波動中的一波，尚待持續觀察。樣帶B因受到干擾，植物組成仍相似，而保持次生狀態，推測只要不再有大干擾，下一階段，物種應不會再有大變化，亦會漸有耐陰性物種進入，並進行自我疏伐。
並列摘要
We conducted two transects (A and B) at a hill-slope belong to Kukuan Training Station of Taiwan Power Company in the Upper Kukuan region in 1990. Every tree individual with a Diameter at 0.5 m height ＞ 1 cm was included to measure its diameter and tree height, identify its species, and then map its relative location. In 2001 ransect A and B were re-censused to know the 11-year change of this secondary forest and the effects of second disturbance. Transect A (0,09 ha) and transect B (0.21 ha) were located in neighbor regions but the Similarity Index was low (IS_(MO)=28.0 %) in 1990. It indicated that they were composed of different kind of vegetation. Moreover, transect B had been disturbed by mudslide caused by Herb Typhoon in 1996. In 1990, the basal-area dominant species of transect A were Mechilus zatkoensis Hayata, Liquidambar formosana Hance, and Trema orientalis (L.) Blume. Trema orientalis (L.) Blume, a shade-intolerant species, declines its basal area in 2001. Moreover, the Important Index of some shade-tolerant species, such as Psychatria rubra (Lour.) Poir and Ardisia cornudentata Mez ssp. morisonensis (Hayata) Yuen P. Yang, were increasing. These made the stand Similarity Index leave only 68.8 %. After 11 years, the basal area of transect A was decreasing (4.5 m^2 to 4.0 m^2), density was almost the same (237 to 238), the mortality was 32.9 %, and the recruitment rate was 33.3 %. The dominant species of transect B in 2001 was similar to those in 1990; before the disturbance of Herb Typhoon. They were Trema orientalis (L.) Blume and Acacia confusa Merr. The similarity between the conducted years was high (ISM0=82.5 %), but actually there have lots of individuals leaving and recruiting. The mortality of transect B was 70.8 %,and the recruitment rate was 178.8 %. Both of them were higher than those of transect A. It showed that natural vegetation could regenerate itself soon after a major disturbance, And the similarity of transect B between 1990 and 2001, indicated that transect B in 1990 was on the recovery stages of another disturbance. The secondary vegetation structures of this transect were: 1. Canopy layer, about 10～15 m, mainly composed of Trema orientalis (L.)Blume and Acacia confusa Merr.; 2. Subcanopy layer, about 4～6 m, mainly composed of Celtis formosana Hayata, Mallotus paniculatus (Lam.) Muell., Broussonetia papyrifera (L.)L'Herit. ex Vent., and Morus australis Poir.; 3. Shrub layer, about 2～3 m, mainly composed of Oreocnide pedunculata (Shirai) Masamune, Callicarpa formosana Rolfe, Ficus erecta Thunb. var. beecheyana (Hook. & Arn.) King, and Maesa perlarius (Lour.) Merr. var. formosana (Mez) Yuen P. Yang. After 11 years, the two transects in the Upper Kukuan region had large changes, and are different to each other. The composition and structure of transect A were probably shift to another stages of succession, or on one point of circular dynamic cycle. It needs continuous observation. Because of disturbance, the composition and structure of transect B was similar between the two census years, and retained to be a secondary forest. If there doesn't have any major disturbance, it is speculated that the composition of transect B won't change much, some shade-tolerant species will recruit in, and the forest will under go self-thinning in the future.