入侵植物互花米草——生物学、生态学及管理

Invasive Spartina alterniflora: biology, ecology and management

近20余年来,互花米草SpartinaalternifloraLoisel.在我国沿海及河口滩涂快速扩散,已成为我国海岸盐沼中最重要的入侵植物。本文介绍了互花米草的形态学、繁殖生物学、生物系统学、分布及全球范围内的入侵途径和历史,探讨了互花米草与沿海滩涂非生物环境、生物环境之间的相互作用及人类活动在互花米草成功入侵中的作用,并得出如下结论:互花米草的成功入侵是在人类活动的影响下,其入侵力(互花米草自身的生物学特性)与入侵生境的可入侵性(滩涂环境对入侵的抵抗力)相互作用的结果,其入侵可能对被入侵地的自然环境、生物多样性、生态系统乃至经济生活带来一系列影响。最后,提出对互花米草的控制只能通过早期预测并保持监控、一旦发现便及时根除的方法来进行。同时,我国应加强立法与相关知识的普及,最大限度地降低互花米草乃至其他外来生物入侵的可能性。

Smooth cordgrass Spartina alterniflora Loisel., a perennial rhizomatous grass native to the Atlantic and Gulf coasts of North America, spreads rapidly in estuaries and coastal salt marshes in the Pacific coast of North America, Europe, New Zealand and China, and has caused considerable effects on the invaded regions. We here describe a comprehensive account of its biology and ecology, and discuss the management of this invasive plant. S. alterniflora was intentionally introduced to China in 1979 for the purposes of erosion check, soil melioration and dike protection. However, its rapid elongation rates, high leaf area indices, high photosynthetic rates, long photosynthetic season and clonal growth make S. alterniflora an aggressive competitor with native salt marsh plants in the coastal regions in China. The estimates made for the year 2002 show that S. alterniflora covered 112000 hectares throughout the eastern China, from Guangxi （21° N） to Tianjin （39° N）, and is still spreading rapidly in the east coast of China. The successful invasion of S. alterniflora in non-native ranges is obviously the result of the interactions between its great invading ability and a high invasibility of the invaded ecosystems, which is further facilitated by human activities. On the basis of its population trend and potential impact on native ecosystems, S. alterniflora was officially placed on the list of most harmful invasive alien plants （nine species） in China in 2003. S. alterniflora invasions in the salt marshes have multiple effects on the abiotic and biotic properties and the functioning of the invaded ecosystems, including conversion of mudflats to Spartina meadows, loss of shorebirds＇ foraging habitats, alteration of ecosystem processes （e.g. carbon and nitrogen cycling）, decrease in abundance of native species, degradation of native ecosystems and their functions, and considerable economic loss. It is predicted that the environmental changes driven by human activities in the coastal regions （e.g. eutrophication, sea level rise and saltwater intrusion） may favour its further invasions in coastal ecosystems in the future. Like other invasive species, it is quite difficult, expensive and even impossible to eradicate S. alterniflora once it has successfully invaded the coastal ecosystems. Obviously, further intentional introductions of S. alterniflora should be banned in China, and effective control measures should be urgently taken, to minimize the negative impacts of S. alterniflora on native ecosystems in China.