大花咸豐草對鬼針的競爭優勢及入侵性探討

Implications of the invasiveness of Bidens pilosa L. var. radiata Sch. Bip. by studying its superiority over Bidens bipinnata L.

徐曉玫(Hsiao-Mei Hsu)

指導教授 ： 高文媛

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.02550

摘要

外來植物的入侵是全球性的現象，且對入侵地的環境及經濟都帶來衝擊。大花咸豐草 (Bidens pilosa L. var. radiata Sch. Bip.) 是目前台灣平地常見野草，被列入台灣危害力最高的二十種入侵植物之一。本研究嘗試初步探討其成功入侵的原因。在台南縣麻豆鎮一處廢耕的柚園中，比鄰生長著大花咸豐草及其同屬的歸化植物鬼針 (Bidens bipinnata L.)；在該地大花咸豐草數量遠超過鬼針，且威脅著鬼針的生存。本研究比較大花咸豐草和鬼針在生理、形態和生活史上的差異，探討在該廢耕柚園中，大花咸豐草爲何具有優勢，以期進ㄧ步了解其入侵成功的可能原因。根據前人對入侵植物的研究，本研究檢驗以下假設：一、大花咸豐草之生活史及生長策略異於鬼針，導致其比鬼針更適應環境；二、大花咸豐草對環境及生物因子展現的外表型可塑性比鬼針高；三、大花咸豐草具有相剋作用的潛力且抑制鬼針的生長。經測量實驗地植株及溫室土壤水分環境控制實驗中的植株葉片，發現大花咸豐草的光飽和淨光合作用速率和第二光合作用系統光使用效率並沒有高於鬼針。然而在模擬冬天的18 ℃環境下，大花咸豐草的種子發芽率、植株光合作用表現均優於鬼針，可能有助其在冬天繼續生長，進而取代鬼針。與鬼針相較，大花咸豐草開花時間較鬼針晚，葉部生物量、葉部面積及側枝比例都較鬼針多，如此可累積較多能量以供持續生長。莖部切片顯示其可能為多年生植物。又其植株倒伏後可行營養繁殖，應有利於族群的擴大。此外大花咸豐草具有相剋作用的潛力，並抑制鬼針種子的發芽，影響小苗的生長。推測以上各點特徵，使得大花咸豐草在該台南廢耕柚園中較鬼針具有競爭優勢，而這些特徵也可能是大花咸豐草成功入侵台灣的部分原因。

關鍵字

大花咸豐草 ； 鬼針 ； 入侵植物 ； 生活史 ； 外表型可塑性 ； 相剋作用

並列摘要

Invasion of exotic plants is a global phenomenon which often has highly impact on the environment and economics. Bidens pilosa L. var. radiata Sch. Bip., a common weed in lowland Taiwan, is listed as one of the twenty most noxious invasive plants in Taiwan. Thus, it is important to study the invasiveness of this weed. Bidens. pilosa var. radiata is found growing closely with Bidens bipinnata L., a naturalized species, and dominates an abandoned farm in Madou Town, Tainan County, Taiwan. Taking the advantage, I compared physiological, morphological and life history traits of these two species aiming to understand possible traits contributing to the invasiveness of B. pilosa var. radiata. I tested the current hypotheses regarding the superiority of invasive plants. Accordingly, B. pilosa var. radiata is expected to have (1) life history traits and growth strategies better adapted to the local environment than B. bipinnata, (2) higher phenotypic plasticity than B. bipinnata and (3) allelopathic potential that inhibits growth of B. bipinnata. Photosynthetic measurements of field plants and plants subjected to different water treatments in greenhouse reveal that the two species had similar photosaturated photosynthetic rate and potential quantum yield of PSII. However, under the winter temperature condition of 18 ℃, B. pilosa var. radiata perfomed better in germination and photosynthesis than B. bipinnata. Thus, B. pilosa var. radiata could have advantage over B. bipinnata in winter. Compared to B. bipinnata, B. pilosa var. radiata has a later onset of flowering and better ability for vegetative reproduction, allocates more resource to leaf, and has higher lateral branch ratio, thus could accumulate more energy for longer growth period. Stem anatomy reveals that B. pilosa var. radiata could have a life span of more than one year. It appears that the two species use different life history strategies. In addition, B. pilosa var. radiata has allelopathic potential that inhibits germination and growth of B. bipinnata. The differences in these traits between the two may explain why B. pilosa var. radiata outcompetes B. bipinnata in the experimental farm and may also account for its invasive success in Taiwan.

並列關鍵字

Bidens pilosa var. radiata ； Bidens bipinnata ； invasive plant ； life history ； phenotypic plasticity ； allelopathy potential

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