水盾草（Cabomba caroliniana）入侵生态系统特征的研究

【作者】 俞建；

【导师】 于明坚；

【作者基本信息】 浙江大学 ， 植物学， 2004， 硕士

【摘要】 水盾草(Cabomba caroliniana)是原产美国和南美巴西等地的多年生沉水植物。自1993年作为新记录报道以来，在中国华东水网地带大面积扩散，并在江苏太湖流域、浙江杭嘉湖平原、宁绍平原等水域成为沉水植物群落的优势种。本研究通过对其入侵水域19个代表性样地及所设置的6个固定样地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： 1、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。 2、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，并且其优势度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15～40％之间，其大小主要与群落种类组成差异有关。 3、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，金鱼藻和黑藻与水质间没有呈现显著的相关性。苦草是生物量和优势度与溶解氧呈显著的正相关。 4、水盾草的生物量与频度分布在4种主要水生植物中是最深的，其生物量的分布主要集中于1.2～1.6m的水深，金鱼藻的分布则是由浅水向深水递减性分布。而黑藻和苦草的分布水深介于两者间。 5、水盾草入侵群落的共存种主要为金鱼藻(Ceratophyllum demersum)、苦草(Vallisneria natans)、黑藻(Hydrilla verticillata)，以及菹草(Potamogeton crispus)、穗花狐尾藻(Myriophyllum spicatum)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。 6、群落的季节动态显示，有些群落在所调查季节中主要优势种都为水盾草(五常乡、柯岩镇和方桥镇)，另一些群落优势种则发生季节性变化(太湖乡、道场乡和陶堰镇)，如太湖乡冬季优势种均为菹草、其它季节为水盾草。 7、从种类组成来看，种类组成单一的群落，水盾草优势度均在50％以上；种类组成复杂的群落，其优势度随季节而变化。说明群落物种丰度与其对水盾草的易感性间有较密切的联系。 8、根据陶堰样地生物量在不同水深的季节动态显示，水盾草的最适生长水深在1.2～1.6m左右的水域，而本地种苦草和黑藻的最适水深在0.8～1m左右，金鱼藻则处于0～0.4m的水深。水盾草在陶堰样地季节动态显示最适水深比本地种大，表明在它们在沉水植物群落中处于不同生态位。 9、水质检测的季节动态显示，水盾草和苦草与水质因子有更密切的相关性。6个水质因子中，溶解氧的变化与两者的优势度更为密切相关，特别是与水盾草的优势度之间，4个样地(方桥水环境被破坏)显示呈负相关。更多还原

【Abstract】 Cabomba caroliniana (cabomba, fanwort) is a perennial aquatic plant originated from the United States, Brazil and other places of in South America. Since it was reported as a new record in 1993,C.Cabomba has been widely spread in the water bodies in eastern China, and becomes the dominance in the submerged plant communities of Taihu lake region in Jiangsu Province, Hangjiahu region and Ningshao Plains in Zhejiang Province. In order to find out the basic characters of the ecosystems invaded by C.Cabomba, community investigation through quadratic method, habitat record, and water quality test had been conducted in 19 typical sites and 6 fixed sites. The results show that:1 Cabomba was an aggressive invader into small or middling rivers or lakes which are slow flowing, most with silt substrate, esp. if they were nutrient rich or middling.2 Cabomba had been the dominant or co-dominant species in the most investigated submerged plant communities, and its dominance negatively correlated with the number of species markedly. Most similarity coefficients of nineteen communities put forward by Spate are 15~40%, and it is related to the number and composing ratio of various species observably.3 The biomass of fanwort has significantly positive correlation with transparency, and its biomass and dominance has markedly negative relationship with dissolved oxygen in the water. The biomass and dominance of Vallisneria natans have significantly positive correlation with dissolved oxygen. But the biomass and dominance of Ceratophyllum demersum and Hydrilla verticillata have no significantly correlation with water quality.4 The maximum biomass of native species and Cabomba were occurred in different depth of water. The suitable depth for Cabomba was approximately 1.2-1.6 meters, while it was approximately 0.8~1.0 meters for native species {Ceratophyllum demersum, Vallisneria natans and Hydrilla verticillata, etc.).5 The main coexisting plants of the communities were Ceratophyllum demersum, Hydrilla verticillata, and Vallisneria natans, Potamogeton crispus and Myriophyllum spicatum were often found as well. It was noteworthy that these species were dominant in many submerged plant communities in the subtropics of China. The dominance of Cabomba negatively correlated with H. verticillata and V. natans observably, it indicated that the invasion of fanwort influenced the existence of the two species.6 The dominant species of the communities were only occasionally changed with seasonsin some places, including the communities of Taihu, Daochang, and Taoyan. Where fanwort always dominated in the Taihu community except it was replaced by Potamogeton crispus in winter season.7 The dominance of Cabomba was also changed with seasons, however it kept a high level (importance value >50%) if the community was simple in species composition. Which means species simple communities can be easily invaded and quickly dominated by Cabomba.8 The maximum biomass of native species and Cabomba were occurred in different depth of water. The suitable depth for Cabomba was approximately 1.2-1.6 meters, while it was approximately 0.8-1.0 meters for native species (Ceratophyllum demersum and Vallisneria natans, etc.).And Hydrilla verticillata was approximately 0-0.4 meter. The suitable depth of Cabomba was always deeper than that of native species with the season changed, which means Cabomba can occupy a unique niche in the submerged plant communities.9 The seasonal dynamics showed that fanwort and Vallisneria natans had more compact correlation with water quality, in six factor of water quality, dissolved oxygen had most compact correlation with the biomass and dominance of fanwort and Vallisneria natans. Especially the biomass of fanwort had positive correlation with dissolved oxygen in 4 fixed sites.更多还原