互花米草的两面性及其生态控制

Positive and negative effects of the non-native plant,Spartina alterniflora and its ecological control

互花米草是美国大西洋沿岸的本土植物,其高生产力、高繁殖率、高抗性和致密发达的地下部分等生物学特性使它能在沿海地区的抗风防浪、保滩护岸、促淤造陆、修复湿地和固定二氧化碳等方面发挥很好的正生态效应;然而,正是这与生俱来的生物学优势使该物种在引种地区侵占光滩,很快形成茂盛的单种优势群落,体现出很强的入侵性,从而也具有相当大的负生态效应。本文综述了互花米草的正负生态效应,分别从以下4个方面展开:抗风防浪的功效与改变景观的负作用,促淤造陆的功效与改变河口水文格局的负作用,固碳效应与释放温室气体的负作用,为一些物种提供营养与栖息地的同时对其他物种栖息环境的破坏性。研究证实,互花米草的本土化倾向已比较突出,如在超过100年引种历史的美国西部维拉帕湾、引种历史近40年的旧金山湾,以及引种历史近30年的我国大丰滩涂等。对于互花米草的生态控制,应结合各地的自然、社会、经济状况,因地制宜,如在一些生态脆弱(开发过度、缺乏大型植被、蚀退现象严重)的沿海地区,防灾减灾任务艰巨,根除互花米草须谨慎;在充分利用互花米草抗风防浪和促淤造陆后,可以适时围垦,以达到某些区域大面积减除的目标;此外,综合治理与利用相结合是较为科学的举措,既充分利用互花米草生物质(加工生产新食品、保健品、生物气等),又有效控制其种子飘落和扩繁,是一项生态工程,也是一种具有生态经济效益的利国利民之举。

Spartina alterniflora Loisel is a native plant along the Atlantic and Gulf coasts in America. With its high productivity, propagation, tolerance, dense and vigorous belowground parts, this species colonizes new mudflats, forms a monocuhure in intro- duced areas, and shows strong invasion potential, thus has negative ecological effects. This study aims to synthesize information on the positive and negative effects of S. alterniflora. Information on naturalization trends of this species is available from Willapa Bay, USA, with an introduction history of more than 100 years, in the San Francisco Bay, USA （ introduction history of nearly 40 y）, and on Chinese coasts （introduction history of 〉 30 y）. There are also positive effects： protecting the seashore from storms, modif- ying the landscape of mudflats ; accelerating land formation, changing the hydrological regime of estuaries ; fixing carbon, decreasing the release of greenhouse gasses; providing habitat and nutrients for some species. However, invsion by this plant also threatens re- gional biodiversity. S. alterniflora should be managed considering the possible benefits. For example, in some coastal regions with serious erosion, the eradication of this exotic should proceed prudently. In shoreline areas with higher sedimentation rate, and in polder reclamation areas, ways of utilisation would be an effective method. Using the vast biomass of this plant as new food source, health products, and biogas could limit its spreading and propagation, and such an ecological engineering could benefit both natural biodiversity and local people＇s income.