Studies on Phenology and Habitat of Helwingia japonica subsp. formosana at Chitou Area

• Main Authors: Wong, Huei-chen, 翁惠珍
• Other Authors: Ying, Shao-shun
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/06658951438397334180

碩士 === 國立臺灣大學 === 森林學研究所 === 88 === Abstract The population structure, phenology, sex ratio and fruiting ratio of Helwingia japonica subsp. formosana were studied in the forests of Chitou area. Other studies such as seed germination, reproduction and habitat conditions were also included. The study area is located on a north-facing slope (5-45%), and ranges in elevation from 1,200 m to 1,360 m. The soils are acid with a relatively high stone content. A total of 32 sample plots were examined. Within each plot, four line transects were set up. Along the transects, all individuals which reached a height of 1.3 m were measured and their Importance value index (IVI) were calculated. For other individuals (<1.3 m height), covers were measured as the intercepted length on line transects. TWINSPAN classification of the 32 plots, based on cover data, revealed two community types. The first type occurred in the stand of Cryptomeria japonica (L. f.) D. Don. The major herbaceous species were Alpinia intermedia Gagn., Alocasia macrorrhiza (L.) Schott & Endl. and Angiopteris lygodiifolia Roenst. The second type was found in the plantation of Chamaecyparis formosensis Matsum., and mainly dominated by Colocasia formsana Hayata, Zehneria mucronata (Blume) Miq., Polygonum chinense L., Glaphyropteridopsis erubescens (Hook.) Ching and Begonia laciniata Roxb. The results of CCA (canonical correspondence analysis) indicated that the strongest community-environment correlations involved canopy dominant type, moisture index and lower canopy closing. Field examination and germination study showed that Helwingia japonica appeared to be a shade-intolerant species with an inverse J-shaped population structure. The seeds showed a capacity for dormancy and had a high germination rate. Both sexual and asexual reproduction by sprouting seedlings seemed to be important means to maintain the populations in the fields. Keyword:Helwingia japonica subsp. formosana, Phenology, Habitat, Vegetation analysis Ⅱ