臺灣的降真香生物學研究

Abstract

本研究為調查臺灣地區芸香科 (Rutaceae) 降真香 (Acronychia pedunculata (L.) Miq.) 之物候學、生育地及植物社會、並進行種子發芽試驗，以瞭解其族群的基礎特性。臺灣的降真香族群數量零散且相對稀少，本研究共在台灣東北部及中西部兩處地區設立20個樣區，其海拔範圍分佈從5 ~ 770 m，利用樣區內對環境因子與各物種重要值的調查，進行雙向指標種分析、矩陣群團分析與降趨對應分析之後，降真香出現的植群社會可區分成5種植群型，若按照各群的優勢物種命名即：Ⅰ林投林型；Ⅱ相思樹林型；Ⅲ卡氏櫧─鴨腳木林型；Ⅳ-1九節木─樹杞亞型；Ⅳ-2紅楠─大明橘亞型。而樣區主要受水分梯度與地形位置兩項生育地環境因子的影響。物候觀察記錄則顯示，降真香全年常綠沒有明顯的落葉期，花期為5月到10月，果期為9月至隔年3月。且降真香的種子在未經過打破休眠的促進處理下，經過播種六個月後發芽率為5.6%。這些基本的研究結果可作為之後降真香保育或繁殖工作的參考。

Acronychia (Acronychia pedunculata (Linn.) Miq.), belonging to the family Rutaceae, is a tree species which widely distributed in Southeastern Asia, but somewhat rare to Taiwan. The study was aimed to basally biological study of the species, such as phenological observation, seed-germination test and vegetation analysis etc. A total of 20 plots were designed in northeastern and central parts of the Island, the elevations of the plots range from 5 to 770 meter above the sea level. At the plots, all ligneous plants which higher than 1.3 meter and diameter of breast height (DBH) more than 1 cm were recorded. By Two Way Indicators Species Analysis (TWINSPAN), Detrended Correspondence Analysis (DCA) and Cluster analysis, three vegetative types and two subtypes were revealed:Ⅰ. Pandanus odoratissimus type, Ⅱ. Acacia confusa type, Ⅲ. Castanopsis carlesii -Schefflera octophylla type, Ⅳ-1. Psychotria rubra -Ardisia sieboldii subtype and Ⅳ-2. Machilus thunbergii - Myrsine seguinii subtype. According to the vegetative analysis, distributions of Acronychia were signified by two environmental factors: moisture gradient class and topographic position. Additionally, Phenological observation indicated that Acronychia is an evergreen tree, its flowering period from May to October, and fruiting from September to May of next year. At last, seed-germination ratio was very low, only 5.6% in our tests. Such low germination ratio may be cause by without any treatment on seed dormancy.