| Summary: | 碩士 === 國立屏東科技大學 === 森林系所 === 100 === The total study area is 288.37 ha, located in the forest compartments No. 23 of Hengchun working circle, Mudan Township, Pingtung County, Pingtung Forest District, Forest Bureau. In this section of Forest conversion, the afforestation area of Cinnamoun camphora and Acacia confuse was up to 191 ha from the past to now. The aiws of This study were to investigate the floristic structure of natural forests and artifical forests ceasing stand tending, explore the relationships between the plant distribution and environmental variables, and research on the current sere. Forty four plots (400 m2 each) were set up and investigated. Thirteen environmental variables were estimated for each plot. The vegetation was classified by two-way indicator species analysis (TWINSPAN) and Detrended correspondence analysis (DCA). The relationships between species and environmental variables were analyzed by Principal Component Analysis (PCA). Furthermore, the significance levels of the eigenvalues of the gradient axes and environment variables were tested by Monte Carlo permutation. By dominance-diversity cruves and the important-value index rank realize the dominance change of each level of vegetation, 365 kinds of vascular plants including 12 rare species were found. The vegetations were classified into five types by PCA, Gordonia axillaris－Adinandra formosana type, Castanopsis fabri－Symplocos modesta type, Saurauia tristyla v. oldhamii－Dysoxylum hongkongense type, Aglaia elliptifolia－Ficus nervosa type and Fraxinus griffithii－Ficus septica type. The axis one and two are significant. The main variables to the floristic variations are altitude, stands index, the herb coverage, the degree of management and the canopy coverage. Dominance-diversity cruves and important-value index rank showed the tree species for plantation were still alive in forest compartment, and the dominant species in south-east climatic region also were the characteristic species in this area. The plantations in this area are transforming from the later phase of secondary forests into natural forests.
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