棲蘭山台灣檫樹繁殖技條葉部性狀之研究

台灣檫樹（Sassafras randaiense (Hay.) Rehder）為台灣落葉性特有闊葉樹種，經評估為易受害（vulnerable）之稀有植物，其亦為寬尾鳳蝶的主要食草，因此在生物及生態上的地位特殊，極具保育價值。本研究針對台灣檫樹冠層空間葉部形態和葉綠素指標值隨時間推移的變化，探討台灣檫樹的調適能力。以棲蘭山神木園區內台灣檫樹為調查對象，於民國87年7月至10月間，平均每14天量測樣木不同冠屬部位之葉長、寬，並以SPAD-502測計同一葉片的葉綠素指標值。利用重複觀測的層級（nested）試驗設計，第一層級為單木，次層級則為冠層垂直層次與水平部位，重複觀測6次。所得結果以SAS混合模式（Mixed Model）程序（Proc Mixed），進行變異分析，求出葉綠素指標值與葉部形態於不同林木位置之樣木間及其冠層空間位置上之變化，以判釋各參數與時間及空間的相關性。結果顯示台灣檫樹葉部性狀在樣木間的效應顯著；台灣檫樹冠層空間內葉綠素指標值及葉面積的變化在不同樹冠水平部位的差異顯著，而在垂直層次上的差異則不明顯。由台灣檫樹葉部形態在時間上的變異分析得知，葉面積之變異大，主要受葉長影響，但自我相關係數隨時間延長而相對降低。葉綠素指標值在10月上旬時變異增大，應與落葉現象有關。

關鍵字

台灣檫樹；葉部形態；葉綠素指標值；葉面積

並列摘要

Taiwan sassafras (Sassafras randaiense (Hay.) Rehder), a native deciduous broad-leaved species, is the sole food source for caterpillars of the endangered broad-tailed swallowtail butterfly (Agehana maraho Shiraki & Sonan). The tree species is also being regarded as a vulnerable species by some researchers. As a part of an ongoing project to understand the population biology and ecology of this species, this study focused on the dynamics of foliar attributes throughout a growing season. The attributes examined included leaf chlorophyll concentration (measured by SPDA-502 chlorophyll meter), leaf length, leaf width, and leaf size. Representing different shading conditions, five trees located at Chilan Shan, northeastern Taiwan, were selected for this study. The canopy of each tree was divided into nine regions; each region was a combination of a relative vertical position (top, middle, or bottom) and a relative horizontal position (outer, central, or inner). For each canopy region, 20 leaves growing on reproductive shoots were subjectively selected and repeatedly measured for six times (from July to October of 1998). The experiment design was thus a repeated-measure nested design with individual tree serving as the primary unit and each canopy region as the secondary unit. A mixed model ANOVA was used to analyze the data. The results showed that chlorophyll concentration, leaf width and leaf size differed significantly among individual trees; trees with an isolated canopy had higher chlorophyll concentration, wider and larger leaves during the observation period. The four attributes did not differ significantly alone the vertical direction. Leaves in the outer and central parts of the canopy had higher chlorophyll concentration and were longer, wider and bigger. In general, the variability of the four attributes increased throughout the growing season, with the last measurement having the greatest variance. The beginning of translocation of chlorophylls by some leaves at the last measurement led to the largest variance in chlorophyll concentration. The four attributes also showed different variation patterns through time. Consecutive measurements of leaf chlorophyll concentration and leaf width did not have a significant correlation. Consecutive measurements of individual leaf length and leaf size, however, had large and significant autocorrelation coefficients, and the autocorrelations decreased with increasing measurement lags.

並列關鍵字

Sassafras randaiense Rehder ； Foliar attribute ； Leaf chlorophyll concentration ； Leaf size

國際替代計量

棲蘭山台灣檫樹繁殖技條葉部性狀之研究

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