西湖沉水植物恢复过程中物种多样性的变化

Change of Species Diversity during the Restoration Process of Submerged Macrophyte in Xihu Lake, Hangzhou

中国湖泊的富营养化与生态系统退化问题已非常严重,太湖、滇池、东湖、西湖等许多湖泊都出现了不同程度的富营养化现象,水生植被消亡、蓝藻水华频发,已经成为制约区域经济社会可持续发展的重要限制因素。沉水植物的恢复重建已成为富营养化水体生态修复的关键手段之一与研究热点。对国家"十二五"水专项的浙江杭州西湖的沉水植物恢复示范区中的物种多样性的变化特征进行了分析,依据植物种在示范区各水域的出现频率与各生活型植物种的组成,探讨了沉水植物恢复过程中植物种绝灭与定居特点。物种多样性指数分析表明:沉水植物恢复工程是沉水植物物种多样性不断增加的过程,恢复工程首先导致恢复示范区内特有种的出现,其次为稀有种。从植物的生活型来看,多年生沉水植物受示范工程的影响最大,而一年生沉水植物可存活于示范工程区的内部与外部,在示范工程区内沉水植物物种的绝灭速率小于定居速率。这表明,在湖泊恢复沉水植物,第一,必须要有一定的保护区域;第二,要合理利用湖泊资源,实行科学的湖泊管理制度;第三,有效恢复沉水植物群落需要经历一定时间与空间的生态重组过程。

The problems of eutrophication and ecosystem degradation in Chinese lakes have been very serious,and many lakes,such as Taihu Lake,Dianchi Lake,Donghu Lake and Xihu Lake,have experienced different degrees of eutrophication.The extinction of aquatic vegetation and the frequent occurrences of cyanobacterial blooms have become an important limiting factor in restricting the sustainable development of regional economy and society.Aquatic plants are the base of the lake food chain and play an important role in maintaining the balance of water ecosystem,controlling algae and purifying water quality.Among them,the restoration and reconstruction of submerged plants has become one of the key means of ecological restoration of eutrophication and research hotspot.This paper analyzed the changing characteristics of species diversity of submerged macrophyte,which was processed in the demonstration zone of the Xihu Lake,Hangzhou City,Zhejiang Province,during the National 12th five-year water project.Based on the frequency of occurrence and the life-form composition of submerged macrophyte species at different areas of restoration project,the colonization characteristics and extinction characteristics of submerged macrophyte species were discussed.The results of analysis,according to species diversity indexes,indicated that the engineering of submerged macrophyte restoration was indeed a process for biodiversity increasing.In particular,endemic species of submerged macrophyte born out firstly during the restoration process,and subsequently the rare species.In terms of the life-form composition,the results revealed that it was the perennial submerged macrophyte species that most severely affected by restoration process,whereas the annual species could live both inside and outside of the ecological restoration engineering area.Additionally,the extinction rate of submerged macrophyte in engineering area was demonstrated to be lower than the colonization rate.Conclusively,when conducting restorations of the submerged macrophyte in lakes,firstly,the particular protected areas for ecological restoration is necessary;secondly it is constructively suggested for reasonable utilization of lake resources,that is to say we need to implement a scientific lake management system,and the last suggestion is that an effective process of restoration engineering by submerged macrophyte needs an ecological restructuring process involves a certain amount of time and space.