基于EHI的洞庭湖生态系统健康综合评价

Comprehensive Assessment of Dongting Lake Ecosystem Health Using EHI

根据2012年3月至2015年12月对洞庭湖入湖断面、湖体断面和出湖口断面的水环境和湖体断面浮游生物的调查数据,采用生态系统健康指数(EHI)法和综合营养状态指数(TLI)法对洞庭湖生态系统健康状态进行定量综合评价。结果表明,洞庭湖湖体TLI值在45.5~49.4之间,整体处于中营养状态,但接近轻度富营养水平,EHI值在41.8~59.8之间,生态系统健康状态为中等。在空间分布上东洞庭湖TLI略高于其它湖区;西洞庭湖区EHI最高,而东洞庭湖区最低。季节性差异上,丰水期(9月)TLI最低而EHI最高,表明洞庭湖丰水期水体营养状况与生态系统健康状态均处于最佳水平。洞庭湖EHI、系统能(Ex)和结构系统能(Ex_(st))等生态指标均与TLI没有显著相关性。与1995-1997年相比,Ex、Ex_(st)和浮游动植物比值(ZB/PB)等生态指标均有明显下降,表明洞庭湖近20年来生态系统健康状况明显恶化。

Seasonal investigations on water environment and plankton were carried out from March 2012 to December 2015 in the three selected regions of Dongting Lake including inlet of the Lake, lake body and outlet of the Lake. Ecosystem health index（EHI） and comprehensive nutrition state index（TLI） were used to assess the ecosystem health state of the Lake. The re-sults showed that the Lake was at mesotrophy level with the TLI between 45.5~49.4 and the status of ecology system health was at medium level with the EHI between 41.8~59.8. EHI displayed a decreasing trend spatially as the Western, Southern,Eastern, while the TLI of Eastern Dongting Lake was a little higher than other regions. Besides, both TLI and EHI showed the best status in September. However there were no significant correlation between EHI, Ex and Exstwith TLI in Dongting Lake.Comparing with 1995 to 1997, the Ex, Exstand ZB/PB decreased significantly in 2012-2015. It showed that the status of ecology system health of Dongting Lake got worse significantly in the recent 20 years.