斗六丘陵植群生態之研究

Abstract

斗六丘陵位於雲林縣、南投縣交界處，研究區總面積約139 km2，海拔範圍100~1,305 m之間，主要為低海拔之丘陵地區，屬於熱帶濕潤氣候，所分布之次生林為八色鳥之重要棲息地，並包含湖山水庫預定地。本研究調查斗六丘陵植群組成及其環境因子，並分析各主要優勢樹種之族群結構，以探討植群之演替情形。總計調查74個樣區，於研究區範圍內維管束植物種類共記錄122科358屬525種，包括蕨類植物70種，裸子植物3種，被子植物452種。其中有55種臺灣特有種，10種稀有種，104種外來種(包含栽培種)，含括67種歸化種。經矩陣群團分析結果，共分出11個植群型，並依優勢種命名：1. 龍眼型；2. 香楠型；3. 千年桐型；4. 相思樹型；5. 豬母乳型；6. 麻竹型；7. 血桐-構樹型；8. 山黃麻型；9. 檳榔型；10. 孟宗竹型；11. 桂竹型等，其中千年桐型、相思樹型為人工林，龍眼型、麻竹型、檳榔型具不同程度之廢耕情形，可作為復舊生態之參考。族群結構分析方面，香楠型、豬母乳型之優勢樹種均呈現反J型分布，表示具有自行更新能力，如不再受干擾，未來可能發展成為榕楠林帶。依降趨對應分析之結果，植群分布序列與環境因子之相關性，以地形位置與全天光空域呈現顯著相關，坡度、坡向、水分指數等則無相關性。各型喬木層之物種歧異度以香楠型最高，其次為山黃麻型，以桂竹型最低。依植群圖繪製結果，斗六丘陵以耕地所佔的面積最大，約7,170 ha，佔總面積52％，闊葉林分布零星，常與竹林混生，面積約3,856 ha，佔總面積30％。依稀有植物保育評估結果，屬瀕危級(EN)的有圓葉布勒德藤1種，近危級(NT)的有鹿谷秋海棠、瓜葉馬兜鈴等2種，易危級(VU)的有岩生秋海棠、鴨腱藤等2種，其中瀕危級之圓葉布勒德藤需特別關注與保育。

Touliu submontane area is located between Yunlin County and Nantou County, and the total area is ca.139 km2. The altitudes of the area range from 100 to 1,305 m above sea level. They are the low-altitude hills with tropical humid climate. The secondary forests are the important habitats of Pitta nympha. In order to investigating the vegetation composition and the environmental factors of Touliu Area, 74 plots, were set up. Moreover, we analyzed their population structures and presumed their succession were analyzed and presumed. Totally 121 families, 357 genera, 525 taxus were recorded, including 55 endemic species, 7 rare species, 106 exotic plants, and 67 naturalized plant species. Based on Matrix Cluster Analysis (MCA), the vegetation were classified into 11 types: 1. Dimocarpus longan type; 2. Machilus zuihoensis type; 3. Aleurites montana type; 4. Acacia confusa type; 5. Ficus benguetensis type; 6. Dendrocalamus latiflorus type; 7. Macaranga tanarius-Broussonetia papyrifera type; 8. Trema orientalis type; 9. Areca catechu type; 10. Phyllostachys pubescens type; 11. Phyllostachys makinoi type. Population structure analysis revealed that most of the dominant species in Machilus zuihoensis type and Ficus benguetensis type were with inversely J-shaped form, which implies that the forests have the ability to self-regenerate. If there were no disturbance, the forest would possibly succeed toward the Ficus-Machilus zone. Based on detrended correspondence analysis (DCA), in terms of the environmental factors, the relationship between distribution of vegetation with toporgraphie position and whole light sky space (WLS) was significant. In overstory, Machilus zuihoensis type gained the highest score of the species diversity index. According to the vegetation mapping of study area, cultivated land occupied the most land area, and covered an area of 7,170 ha at 52％ The broadleaved forest was distributed brokenly, or mixed with bamboo forest, and occupied about 3,856 ha at 30％. An consvervation evaluation of rare plant, Bredia hirsuta var. rotundifolia was endangered, need concerning.