| Summary: | 碩士 === 國立臺灣大學 === 植物學研究所 === 83 === The purpose of this study is to understand the β-diversityalong an altitudi-nal gradient. A one-hectare transect, which is 500 m long and 20-40 m wide at altitudes of 220-467 m, was established on the northwestern ridgeof Nanjenshan, Kenting National Park. Inventory of woody plants in the transect was conducted, and DBH, height,and growth condition for each individual were recorded.
A total of 139 woody species, belonging to 49 families and 91 genera, were recorded. Among them 99 were trees, 30 shrubs and 10 lianas. The most dominant sprcies is ~u2;Ilex cochinchinese~u1; with an important value (IV) of 7.61% and 533 individuals; the second dominant one is Syzygium euphlebium with an important value of 6.02% and 200 individuals. In general, the forest showed a strong dominance, that is, 43.55% of the dominance were shared by the first ten species.
The result of Detrended-Cerresponding Analysis (DCA) showes
that the transect can be divided into three vegetation zones
along the altitudinal gradient. Four types of species distri-
bution pattern were classified based on the peak of dominance
along the altitudinal gradient. Dominance at the family level
also tends to change along the altitudinal gradient reveals that
a sharp transition from semitropical to temperate forest type.
15 species of six genera are found with congeneric niche
differensiation along the altitudinal gradient.
The slope of regression formula, Y=-0.0019x+0.5925, which is plotted by community coefficient to altitudinal differencies, is β-diversity. These result suggest high α-diversity and community changes when the altitudinal varies over the range of 300 m.
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