三峡水库消落带外来植物组成及分布特征

目的]探究三峡水库消落带外来植物的物种组成及分布特征，为库区外来植物管理防控、生物多样性保护和生态安全管理提供理论支持和数据参考。方法]通过对库区消落带外来植物的实地调查，结合文献资料，研究外来植物的物种组成、原产地、引入途径、生活型及消落带外来植物的分布现状。结果]三峡水库消落带存在66种外来植物，隶属于22个科50属，其中菊科、豆科、茄科和苋科是三峡水库消落带外来植物的优势科，共有40种，占总种数约60.6%，菊科的数目最多，达到21种；外来植物中来源于美洲的物种最多，达到66.7%；生活型以一年生草本植物居多；花果期多集中于5—10月份；外来植物中分布最为广泛的物种是大狼杷草、喜旱莲子草、鬼针草、钻叶紫菀、小蓬草和土荆芥；三峡水库内库首和库中区域消落带分布的外来植物较多。结论]三峡水库消落带外来植物种类较多，分布广泛，在常年回水区外来植物入侵态势较为严重，入侵植物防控的形势不容乐观。建议结合消落带管理方法和消落带植物群落特征建立外来植物防治机制，积极采取相关措施，加强消落带外来植物扩散机制及其对本地生态系统影响的研究。

Composition and distribution characteristics of exotic plants in the water-level fluctuating zone of the Three Gorges Reservoir, China

Aim] In order to minimise the unwanted ecological effects of the Three Gorges Reservoir, we studied the species composition and distribution characteristics of exotic plants in the areas of the reservoir that is periodically inundated by the fluctuating water level.Method] Through field surveys of exotic plants in the fluctuating water zone, supplemented by literature data, the species composition, origin, introduction method, life form, and distribution status of exotic plants were studied.Result] In total, 66 species of exotic plants belonging to 22 families and 50 genera were recorded. Among them, Compositae, Leguminosae, Solanaceae, and Amaranthaceae were the dominant families, with a total of 40 species that accounted for approximately 60.6% of all the species identified. Species beloniging to the Compositae family had the largest number, with 21 species. Non-native the species from America were the most abundant, comprising 66.7% of all detected species. Annual herbs were the most common life form, and the flowering and fruiting periods were mainly from May to October. The most widely distributed species were Bidens frondosa L., Alternanthera philoxeroides (Mart.) Griseb., Bidens pilosa L., Symphyotrichum subulatum (Michx.) G. L. Nesom, Erigeron canadensis L., and Dysphania ambrosioides (Linnaeus) Mosyakin & Clemants. Overall, many exotic plants were distributed throughout the water-level fluctuating zone at the head and the middle of the Three Gorges Reservoir.Conclusion] There were numerous species of exotic plants widely distributed throughout the water-level fluctuation zone of the Three Gorges Reservoir. The invasion of exotic plants was severe, especially in the perennial backwater area, and the prevention and control of invasive plants was not effective. It is suggested that prevention and control mechanisms for exotic plants be combined with the management methods of the fluctuation zone. Moreover, these mechanisms should be created with the characteristics of the plant community in mind.