三峡工程对洞庭湖水力梯度及其湿地植物生长的影响

水力梯度是制约洞庭湖湿地植物生长的主要因素.通过分析三峡水库运行前后洞庭湖水力梯度的变化来研究其对洞庭湖湿地植物的影响,能为该区植物多样性及退化生态系统的恢复提供科学依据.研究表明,三峡工程的运行不同程度上降低了洞庭湖的水力梯度,且枯水期的影响大于丰水期.其中东洞庭湖受其影响最为明显,特别是在4月和10月,洞庭湖其他地段水力梯度变化较为平稳.三峡工程对洞庭湖湿地植物的影响是枯水期大于丰水期,除了4月和5月对洞庭湖湿地植物的生长产生不利的影响外,其他月份有着有利的影响或影响不大.

Effects of Three-Gorge Project on hydraulic gradient and vegetation growth in Dongting Lake wetland

The present paper aims to introduce the authors' research on the influence of the Three-Gorge Project on the vegetation growth in Dongting Lake wetland through studying the change of hydraulic gradient of Dongting Lake before and after the project put into operation. The study also aims to provide scientific bases for the further research of the botanical diversity and restoration of degenerated ecosystem in Dongting Lake area. As is known, hydraulic gradient is the main factor restricting the vegetation growth. The present study helps to disclose the following facts: 1)The influence on the fenny meadow may not be great from February to March of the following year. It is advantageous of swamp and billabong to conserve the bodies of aquicolous vegetation and germination of seeds in March. 2)In April, it is bad for the carex distributing in the east of Dongting Lake to grow. And in October, the effect on bulrush is very low because of the stable and steady growth of accumulation. 3) In May, higher hydraulic gradient may have certain bad effect on the bulrush distributing especially in the eastern Dongting. The growth of most vegetation in Dongting Lake will be subjected to the bad effect because of the higher hydraulic gradient. 4) In November, it is advantageous for the wetland vegetation because of the slight change of hydraulic gradient. 5)Due to the slight change of hydraulic gradient from June to September, there can not be found any great effect in the successive months of July, August and September.