雪山主峰沿線植群生態之研究

Abstract

本研究為了解雪山主峰線沿線之植群結構組成以及物種多樣性與環境因子之關係，彙整前人28個樣區並補設中低海拔18個樣區，自七家灣溪沿步道至雪山主峰(海拔3,886 m)共46個250 m2樣區，共記綠383種維管束植物。沿線植群依外觀形態可大致區分為森林、灌叢及草原等3類植群；森林植群依群團分析結果劃分為臺灣冷杉型、巒大花楸型、玉山圓柏型、臺灣二葉松型、臺灣雲杉型、狹葉高山櫟型、紅檜型、臺灣紅豆杉–臺灣灰木型、卡氏櫧–西施花型、高山櫟–鐵杉型、栓皮櫟–化香樹型等11個森林植群。以及玉山圓柏–玉山杜鵑型之灌叢植群和玉山箭竹–高山芒型、高山芒型、高山艾型等3個草本植群。排序結果顯示影響森林植群型分布之環境因子主要為海拔，其他因子如坡度、坡向及全天光空域之影響力不若海拔梯度明顯。各植群內的直徑級結構結果顯示各植群型多數優勢種之徑級分布圖呈現倒J型曲線，顯示其更新良好。α尺度物種多樣性之豐多度及豐富度沿海拔變化趨勢皆呈先小幅上升而後下降的單峰型態，均勻度則隨海拔梯度的變化無明顯之趨勢；β尺度之兩種相似性指數隨海拔梯度上升而上升。各植群型間各生活型於生活型譜之比重有異，各植群亞型之生活型結構組成亦有所差異，由植群之生活型譜可推測該植群於其生育地之生存策略。

The study compiled reviewer''s 28 plots and sampled 18 plots(10×25 m2) and recorded 383 species from 1,682 m to 3,886 m along the east trail of Mt. Shei. Vegetations can be broadly distinguished into three physiognomic categories: forest, shrub, and grassland communities. One shurb vegetation was Juniperus squamata-Rhododendron pseudochrysanthum type, and three grassland vegetations were Yushania niitakayamensis-Miscanthus transmorrisonensis, Miscanthus transmorrisonensis, and Artemisia oligocarpa type. Through cluster analysis, there are 38 forest sampled plots classified into 11 forest types: Abies kawakamii, Sorbus randaiensis, Juniperus squamata , Pinus taiwanensis , Cyclobalanopsis stenophylloides , Picea morrisonicola , Quercus variabilis-Platycarya strobilacea , Taxus sumatrana-Symplocos formosana , Castanopsis carlesii-Rhododendron ellipticum , Quercus spinosa-Tsuga chinensis and Chamaecyparis formosensis type. Furthermore, canonical correspondence analysis indicated the distribution of forest communities was significantly correlated with altitude. Moreover, population structure of most dominant species revealed anti-J-shaped that indicate their regeneration well in forest vegetations. In alpha diversity, species abundance and richness generally showed a slight increase initially and then decline gragually along altitudinal gradient. Eevenness index has no obvious trend. In beta diversity, two kinds of similarity index decline with the increasing elevation. The life-form spectrum representing the survival strategy during adverse season was different among plant communities along altitudinal gradient.