雪山主峰線臺灣冷杉族群結構研究

Study on population structure of Abies kawakamii (Hayata) Ito in East Xue Trail of Xue Mountain

臺灣冷杉（Abies kawakamii （Hayata） Ito）主要分布臺灣3,000-3,600 m高海拔山區，常以純林呈現，為臺灣特有種裸子植物。本研究於雪山主峰線探討臺灣冷杉不同林分之族群結構，並彙整製作靜態生命表，探討臺灣冷杉族群動態變化。沿雪山主峰線設置7個50 m×40 m之樣區，總計調查臺灣冷杉有800株，密度571株/ha，各樣區主要伴生木本植物有臺灣鐵杉、玉山圓柏、玉山杜鵑、巒大花楸等。由7個臺灣冷杉林樣區族群結構來看，可將雪山主峰線不同林分之臺灣冷杉徑級結構分成鐘形分布、雙峰分布及反J型分布等3種類型，其中以鐘形分布最為常見。然而彙整本區各樣區臺灣冷杉株數繪製臺灣冷杉族群徑級分布圖，則為反J型分布，反映出演替後期成熟林之結構特性；根據靜態生命表之結果，雪山主峰線臺灣冷杉族群之生存曲線近趨Deevey-III型，屬於小苗死亡率高，成熟後死亡率降低而漸趨穩定。依死亡曲線與致死率曲線發現臺灣冷杉在1-20 cm、60-80 cm，以及 >100 cm等3個死亡高峰期，分別反映出稚樹期、青壯期因競爭自疏死亡，而老齡木因生理衰老死亡的狀態。根據各樣區地被類型，以苔蘚植物為主之地被層，臺灣冷杉小苗數量較多，而玉山箭竹為優勢之地被類型，臺灣冷杉小苗數量較少，顯示玉山箭竹優勢對臺灣冷杉更新有一定之抑制作用。 Abies kawakamii (Hayata) Ito is the endemic species in Taiwan. It also forms pure forest type at the subalpine ecology at the altitude 3,000-3,600 m mountain area in Taiwan. We investigated the population structure of A. kawakamii at different stands in East Xue Trail of Xue Mountain and constructed static life table to discussion the population dynamics. Seven sampling plots (50 m×40 m) were set along the East Xue Trail of Xue Mountain. Totally investigated 800 stems of A. kawakamii, density is 571 numbers of stem/ha. The associated trees are Tsuga kawakamii, Juniperus squamata, Sorbus randiensis, and Rhododendron pseudochrysanthum. Analysis the diameter at breast height (DBH) class of A. kawakamii at 7 sampling plots in different stands, can divided population structure distribution into 3 types: bell shaped curve, two-peak shaped curve, and reverse-J-shaped curve. At the same time we synthesize all numbers of stem, the DBH class distribution belong to the reverse-J-shaped curve in the A. kawakamii forest type. Reverse-J-shaped curve can reflect the structure characteristic of mature forest at the post succession. Then according the results of the static life table, A. kawakamii seedlings have high ratio death rate. This survivor curve of A. kawakamii population is Deevey-III type in East Xue Trail of Xue Mountain. If the seedlings can growth to adult trees, the death rate would decrease to stable. According the death curve and killingpower curve, the DBH class at 1-20 cm, 60-80 cm, and >100 m stage had highly death ratio. This can reflect A. kawakamii at the sapling and adult period had self-thinning caused by competition, then old age wood physiologically grow to death. Furthermor, based on the understory vegetation type, at the moss dominance type the seedlings numbers of A. kawakamiiare highly than the Yushania niitakayamensis dominance type. It means the Bamboo dominates would impede A. kawakamii regeneration..