| Summary: | 碩士 === 國立高雄師範大學 === 生物科技系 === 96 === The research site was located at Siaping area in Jhushan, Nantou, central Taiwan. This study aims to understand the stand structure and vegetation dynamics of the secondary forest in the abandoned field.
A total of 10 plots (20m×20m) were set up in the study site which covered an area of 2.2 ha with an elevation of about 155 meters above sea level. A total of 41 families, 73 genera, and 88 species of vascular plant were recorded, including Pteridophytes, Herbaceases, Lignosaes, and Monocotyledons.
According to the results by analysis of the dominant species with the Important Value Index (IVI) method, there were seven tree species with a IVI of greater than 10, including: Machilus zuihoensis, Litsea hypophaea, Mallotus paniculatus, Melia azedarach, Macaranga tanariusm, Capparis sikkimensis ssp. Formosana, and Bridelia tomentosa, with a total value of 254.53 occuring up to 85% of all the vegetation in the research sites. It showed that the dominant species were focused on these seven species and Machilus zuihoensis took possession with the IVI value of 109.73, becoming the most dominant species among them in the field.
There was one forest type determined by the analysis of TWINSPAN method, the Machilus zuihoensis forest type. The diameter structure in the area displayed invert J-shaped distribution. It indicated the growth of different tree species in the field was stable, except for Melia azedarach, which had a rotated S-shaped but tended toward J-shaped scatter, showing that its regeneration situation was weaker than the others.
The results of the trunk analysis of different Machilus zuihoensis samples showed that the biggest one was 15 years old. We conjectured that this forest was established at least 20 years if we put the previous 5 years under the dominantion of Miscanthus floridulus into the calculation.
Furthermore, the numerous seedlings of the gap species such as Litsea hypophaea, Capparis sikkimensis ssp. formosana and Bridelia tomentosa were widespread in the forest so we concluded that the stand development was moved to the understory recovery period.
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