| Summary: | 碩士 === 國立臺灣大學 === 生態學與演化生物學研究所 === 105 === Bidens pilosa var. radiata is a perennial invasive plant in Taiwan. Eradication is the most often used method to inhibit the spread of invasive plants in Taiwan. In this research, I conducted a field survey to examine whether the method is applicable to control the population of B. pilosa var. radiata. After eradicating all plants growing in a farm, in Peitou, dominated by B. pilosa var. radiata, I found that annual species dominated the plots at the beginning of the succession but they died out soon, and subsequently, B. pilosa var. radiata became dominant again. Therefore, eradication alone cannot control the population of B. pilosa var. radiata. According to previous studies, planting suitable native species might be able to prevent the invasion of invasive plants after their removal. Sambucus chinensis and Urena lobata are two native perennial species producing seed size compatible to B. pilosa var. radiata. In the second part of this study, I evaluated whether planting these two native species could inhibit the population size of B. pilosa var. radiata after its eradication. I compared seed germination, seedling growth, physiological and growth traits of the three species and also investigated allelopathic effects. Results of seed germination experiments revealed that among the three species, B. pilosa var. radiata had the highest germination percentage, U. lobata had the fast germination rate at the temperature of 30 ̊C/25 ̊C, while S. chinensis did not germinate during the incubation period of 11 days. During the six weeks of culture period in winter, seedlings of U. lobata had higher plant height, accumulated more biomass and more leaf area than those of B. pilosa var. radiata. In summer, seedlings of U. lobata and B. pilosa var. radiata had similar plant height and biomass at the end of the 6-week of culture period. When the culture period was extended to 3 months, U. lobata accumulated more biomass than B. pilosa var. radiata. S. chinensis had similar biomass but lower plant height than B. pilosa var. radiata after 6 weeks of culture period. In general, I did not find that aquatic extracts of S. chinensis and U. lobata had apparent effect on seed germination and growth of B. pilosa var. radiata. According to these results, I suggested that sowing the seeds or planting the seedlings of U. lobata might be able to control the population size of B. pilosa var. radiata after the eradication treatment in summer. However, S. chinensis might not be a good candidate for the application.
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