【摘要】 水盾草 (Cabombacaroliniana)是原产南北美洲的沉水植物 ,常被作为水族馆植物引种至世界各地 ,近年来开始入侵我国沉水植物群落。该文通过对其入侵水域 1 9个代表性地点的群落学调查和水质测试 ,研究其入侵生态系统的基本特征。结果表明 :水盾草入侵群落的水域类型均为水流平缓的中小型河流和湖泊 ,水质大多属中营养化和富营养化。水盾草在所调查的大部分沉水植物群落中基本上为优势种或共优种 ,并且其重要值与物种数呈显著负相关。群落间相似性系数 (Spatz指数 )大部分在 1 5 %～ 4 0 %之间 ,其大小主要与群落种类组成差异有关。水盾草的生物量与水体透明度呈显著正相关 ,生物量和优势度与溶解氧呈显著负相关 ,频度和生物量在 0 .4～ 1 .2m的水深处最高。水盾草入侵群落的共存种主要为金鱼藻 (Ceratophyllumdemersum)、苦草 (Vallisnerianatans)、黑藻(Hydrillaverticillata) ,以及菹草 (Potamogetoncrispus)、穗花狐尾藻 (Myriophyllumspicatum)等 ,它在群落中的优势度与金鱼藻无显著的相关性 ,但与黑藻和苦草呈显著负相关。估计水盾草在我国尚有较大扩散空间 ,水域众多、营养化程度较高的亚热带平原地区是其最适入侵区 ,应加强基础和防除研究更多还原

【Abstract】 Cabomba caroliniana (common names: Cabomba, Fanwort) is a submerged plant from the USA and South America that was introduced into China in the 1980s as an aquarium plant for its beautiful and finely dissected submerged foliage. Cabomba is now distributed widely throughout the Changjiang River Delta in East China and has become a dominant species in many submerged plant communities in this region. In order to better understand the ecology of Cabomba, we investigated 19 communities dominated by Cabomba and measured the species composition, habitat characteristics, and water quality parameters during the summers of 2001 and 2002. Our results showed that Cabomba was an aggressive invader of slow flowing, small to middle_sized rivers and lakes with silt substrates, particularly in waters that were nutrient rich. The average water quality characteristics of these ecosystems were: transparency = 0.60 m-1.45 m, pH value = 6.19-7.51, total nitrogen = 0.14-3.27 mg·L -1 , total phosphorus = 0.044-0.838 mg·L -1 , COD Cr = 1.96-8.15 mg·L -1 , DO = 1.23-7.32 mg·L -1 . These habitat characteristics are similar to those measured in its habitat in the USA and Australia. Suitable water depth was 0.4-1.2 m and varied among the study sites. Cabomba was the dominant or co_dominant species in most communities investigated, and its dominance was strongly negatively correlated with the total number of species in the community. It is highly probable that the species diversity decreased after invasion by Cabomba. The biomass of Cabomba had a significant positive correlation with water transparency, and its biomass and dominance had a strong negative relationship with dissolved oxygen in the water. This indicated that Cabomba preferred high light conditions like most other submerged plants but can tolerate lower dissolved oxygen concentrations. Most similarity coefficients as put forward by Spatz were 15%-40% for the 19 communities and were related to the number and composition ratio of the various species. The main co_dominant plants of the communities were Ceratophyllum demersum, Hydrilla verticillata, Vallisneria natans, Potamogeton crispus and Myriophyllum spicatum were somewhat common as well. It was noteworthy that these species are dominant in many submerged plant communities in the subtropics of China. The dominance of Cabomba was negatively correlated with H. verticillata and V. natans. This indicates that the invasion of Cabomba influenced the existence of the two species. In conclusion, Cabomba invaded the Changjiang River Delta, a relatively developed region in P. R. China, by escaping from aquaria. It quickly became widespread because of its comparatively better adaptability to these habitats and its stronger ability to spread vegetatively than many native submerged plants. The preferred habitat of Cabomba was slow flowing subtropical waters with high to moderate nutrient levels. The waters Cabomba inhabited were mostly polluted from industrial, agricultural, and domestic sewage runoff. Cabomba most easily invaded communities dominated by Ceratophyllum demersum, Hydrilla verticillata and Vallisneria natans; thus, these three species can be regarded as indicators of easily invasible communities. The invasion of Cabomba requires more basic research in order to establish effective measures to control the spread of this species in China.更多还原