台灣北部福山地區雞屎樹屬(Lasianthus Jack)種間分佈型差異及其和環境梯度變化相關性之研究

Abstract

本研究目的為探討福山試驗林區雞屎樹屬(Lasianthus Jack，Rubiaceae)屬內各種在實驗林區範圍內的分佈情況，及其分佈型與林地內數種重要環境因數之間的關連性。於福山試驗林範圍內設置31個10×10 m2或20×5 m2樣區，並將每一樣區分別劃分成4個5×5 m2的小樣區，調查小樣區內所有的雞屎樹植株（包括小苗及幼樹），記錄每株雞屎樹的高度及樹冠覆蓋度。再選定7種較可能影響植種分佈的環境因數，於每一樣區內觀測記錄：1.海拔高度，2.坡度，3.樣區方位，4.地形，5.樹冠鬱閉度，6.土壤水分百分率，以及7.土壤pH值。調查所得之植物社會資料及樣區環境資料，運用降趨對應分析(Detrended Correspondence Analysis, DCA)，瞭解物種隨各項環境梯度的分佈變化情形。在福山試驗林共調查到雞屎樹屬植物9種及2變種：密毛雞屎樹(L. appressihirtus Simizu)、大葉密毛雞屎樹(L. appressihirtus Simizu var. maximus Simizu ex Liu & Chao)、文山雞屎樹(L. bunzanensis Simizu)、柯氏雞屎樹(L. curtisii King & Gamble)、琉球雞屎樹(L. fordii Hance)、台灣雞屎樹(L. formosensis Matsum.)、日本雞屎樹(L．japonicus Miq.)、粗毛日本雞屎樹(L. japonicus Miq. var. satsumensis (Matsum.) Makino)、小葉雞屎樹(L. microphyllus Elmer)、薄葉雞屎樹(L．microstachys Hayata)及圓葉雞屎樹(L. wallichii Wight)，由降趨對應分析結果可得知：海拔高度、坡度及地形3因數應為影響雞屎樹在福山試驗林分佈的關鍵因數；同時，針對琉球雞屎樹在試驗林出現的4種外部形態變異亦進行降趨對應分析之工作，結果顯示福山地區的琉球雞屎樹，植株密被短粗毛及幾乎不被毛的兩族群在生育地偏好上有產生差異的趨勢，尤其是針對海拔高度及坡度這兩項因數而言。

The subject of this research is to study the distribution of the species of genus Lasianthus Jack (Rubiaceae) in Fushan experimental forest, and the relationship between the distribution and several improtant environmental factors of the forest. We set 31 10×10 m2 or 20×5 m2 plots in Fushan, then divide each of them into 4 5×5 m2 small plots. Record the coverage and height of each Lasianthus sp. in the plot (including the seedling and sapling). By chooseing 7 environmental factors which could affect the distribution of species: 1. altitude, 2. slope, 3. aspect, 4. topology, 5. tree layer closure, 6. soil moisture (percentage), and 7. soil pH value, we record the 7 factors of each plots. After the investigation of the phytosociological datas and environmental datas of plots, we use DCA (detrended correspondence analysis) to understand the change pattern of species' IVI value along with teh environmental gradient. We record 9 species and 2 variaties of the genus Lasianthus Jack, in Fushan experimental forest. These are L. appressihirtus Simizu. L. appressihirtus Simizu var. maximus Simizu ex Liu & Chao, L. bunzanensis Simizu. curtisii King & Gamble. L. fordii Hance, L. formosensis Matsum.. L. japonicus Miq., L. japonicus Miq. var. satsumensis (Matsum.) Makino. L. microphyllus Elmer, L. microstachys Hayata, and L. wallichii Wight. From the result of DCA. we know that altitude, slope and topology should be the key factors to the distribution of the plants of L. species in Fushan. And. we also analyze the 4 morphological variances of L. fordii Hance by DCA. The result shows that there are some differences between the population of the variances which densely hirsute and which are glabrous or subglabrous. especially in altitude and slope, these two environmental factors.