| Summary: | 碩士 === 國立臺南大學 === 環境生態研究所碩士班 === 94 === The Takuanshan area is located at the southwest part of Yushan National Park in Taiwan. This study is aimed to investigate the composition, structure and the dynamics of the hemlock forest. A 1.8-ha permanent plot was established which is 180 m long and 100 m wide at altitudes of 2580-2640 m in Takuanshan area. All woody plants larger than 1cm DBH were tagged, identified, measured and mapped. A total of 3,921 individuals, which belonged to 32 species was found in this plot. This forest could be divide into three layers, canopy layer, second layer and understory layer. The canopy layer was dominated by Tsuga chinensis var. formosana, Chamaecyparis formosensis and Pinus armandii var. masteriana. The second layer was dominated by Eurya glaberrima, Pasania hancei var. ternaticupula and Schefflera taiwaniana. The understory layer was dominated by Yushania niitakayamensis and some ferns. The results of TWINSPAN showed that the permanent plot could be divided into three phases, gap phase, building phase and mature phase. The mature phase had the largest basal area (115.4 m2 /ha), then building phase (91.71m2 /ha), and the third gap phase (12.43 m2 /ha). But, the building phase had the largest density (2776 inds./ha), then gap phase (1782 inds./ha), and the third mature phase (1345 inds./ha). In gap phase, the density of Chamaecyparis formosensis was heigher than Tsuga chinensis var. formosana and Pasania hancei var. ternaticupula. In building phase, the density of Tsuga chinensis var. formosana was heigher than Chamaecyparis formosensis, and the average basal area of Tsuga chinensis var. formosana was heigher than Chamaecyparis formosensis and Pasania hancei var. ternaticupula. In mature phase, Tsuga chinensis var. formosana was the dominant species at this phase. The results showed that Tsuga chinensis var. formosana would exceed Chamaecyparis formosensis and Pasania hancei var. ternaticupula in this forest. The results of Canonical correspondence analysis showed that Tsuga chinensis var. formosana, Pasania hancei var. ternaticupula and Rhododendron rubropilosum had positive correlation with canopy openness and slope, while Chamaecyparis formosensis, Pinus armandii var. masteriana and Eurya glaberrima had positive correlation with aspect and altitude. The results can be applied for dynamic study and other related studies in the future.
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