洞庭湖生态风险评价及阶段性特征

采用“压力－响应”模式,按3个阶段评价了洞庭湖1991~2015年生态风险状况,并识别了不同阶段的主要压力源、胁迫因子及受影响较大的生态系统指标与生态系统服务.结果表明：（1）1991~2015年,洞庭湖生态风险总体呈不断增加趋势,期间造成洞庭湖生态风险增加的主要压力源发生了较大变化;主要胁迫因子和受影响大的生态系统指标也变化明显,而受影响较大的生态系统服务功能无明显变化.（2）不同阶段,洞庭湖生态风险影响因素不同,其中1991~2002年,受自然源和人为源共同影响;2003~2010年,自然源影响明显减弱,而人为源影响逐步增加;2011~2015年,自然源影响继续降低,而人为源的影响则进一步增加;（3）近年来洞庭湖生态风险增速虽有所减缓,但生态风险增加趋势尚未根本性改变,仍需加强洞庭湖保护治理,重点是进一步加强流域人为源的污染控制,同时密切关注自然源影响,尤其是水文情势变化所引起的生态风险增加问题.

The ecological risk assessment and stage characteristics of Dongting Lake

To protect Dongting Lake more effectively, it is very important to evaluate the ecological risk of Dongting Lake quantitatively. In this paper, the "Pressure-Response" model was adopted to evaluate the ecological risk status of Dongting Lake from the viewpoint of three stages from 1991 to 2015 and identify the main pressure source, stress factors and the main affected ecosystem indicators, ecosystem services of different stages. The results showed that (1) the ecological risk of Dongting Lake increased continuously from 1991 to 2015, and its main pressure source changed greatly. The main stress factors and the main affected ecosystem indicators were also changed obviously, but the main ecosystem services had no significant change. (2) The ecological risk factors of Dongting Lake were different at different stages. From 1991 to 2002, the ecological risk was influenced by both natural and social sources; From 2003 to 2010, the influence of natural sources was weakened, the influence of social sources began to emerge. From 2011 to 2015, the influence of natural sources was relatively small, and the influence of social sources was big. (3)Although the growth trend of ecological risks has slowed down in recent years, but which was still needed to strengthen protection and governance. It was to strengthen the pollution control of social sources continually in the basin, and to pay close attention to the changes of natural sources, especially the increasing of the ecological risk caused by the changes in hydrological conditions.