| Summary: | 碩士 === 國立臺灣大學 === 森林環境暨資源學研究所 === 101 === Seed dispersal is critical for the distribution of plant populations. Mistletoes is a groups of hemi-parasitic plants and their seeds are directly dispersed by flowerpeckers in Taiwan. Mistletoe seeds can establish only at particular safe sites of germination. Condition of seed deposit site, such as light, compatibility to host trees, and branch size, all affect the success of mistletoe seeds. Therefore, where mistletoe seeds are dispersed determines the establishment of the parasitic mistletoes. This study was aimed to determine the seed fate of Taxillus tsaii, and to examine how seed depositions are affected by the movement of flowerpecker. During July to September, 2011, I investigated the tree height, crown diameter and number of mistletoe plants of the major host (Camellia oleifera) of Taxillus tsaii in Lien-Hwa-Chi Research Center, and I counted the number of mistletoe seed deposition, exocarps of mistletoe fruits, and drop fruits attached to plants and on ground. I also recorded the movement of flowerpeckers among host trees and the horizontal distribution of mistletoe seeds on host plants. Results show that flowerpecker visit and seed deposition were higher in trees parasitized by mistletoes. The host trees that experimentally removed mistletoe flowers and fruits received significantly lower seed deposition, only about 15% of seed deposition of controls. I founded seed deposition were greater in larger crown trees. Trees with larger crown were parasitized by more mistletoes, offering more food resource for flowerpeckers and receiving more seed depositions in return. This positive feedback between mistletoes and flowerpeckers led to the clumpy distribution of mistletoes. About 45.6% of mistletoe fruits consumed and, after dispersed by flowerpeckers, seed deposition on the 40 sample hosts was only about half of fruit consumption, indicating frequent movement of flowerpeckers brought large percentage of seeds away from their previous hosts. Only 11.3% of the seed deposition was landed on safe sites, and most seeds were deposited on unsuitable sites (lower branch, mistletoe, and ground). This might because the defecated seeds of Taxillus tsaii are not as viscous as other mistletoe species and usually drop directly from cloaca, leading to decreased efficiency of seed dispersal. Flowerpeckers, as the only effective seed dispersers for mistletoes in Taiwan, provide benefit and limitation to the dispersal of mistletoes. Further studies are needed to examine their relationships in details.
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