洪湖湿地生态系统演变及稳态转换关键驱动因子阈值研究

利用1990—2020年洪湖水环境监测数据和2011—2020年洪湖沉水植物调查数据,探讨洪湖湿地生态环境演化规律,识别稳态转换关键驱动因子并确定其阈值。研究结果表明:1990—2020年以来洪湖水质变化主要总结为5个阶段和3个时期,整体上呈现出不断恶化的趋势;2011—2020年以来洪湖沉水植物Margalef物种丰富度指数、Shannon-Wiener多样性指数、Simpson和Pielou均匀度指数分别降低32%、59%、60%和46%,特别是2016年洪涝灾害后沉水植物出现严重衰退;洪湖生态系统发生稳态转换的关键时期是2002和2011年,总磷是洪湖湿地生态系统稳态转换的关键驱动因子;清水态向浊水态转换的总磷阈值为0.092 mg/L,浊水态向清水态转化的阈值为0.051 mg/L。本研究可为洪湖入湖污染负荷削减量估算提供参考,为洪湖湿地生态修复的营养盐优先控制策略提供指导。

Evolution mechanism of Lake Honghu wetland ecosystem and regime shift crucial threshold

Based on the environment monitoring data from 1990 to 2020 and the aquatic plant survey data from 2011 to 2020 in Lake Honghu, the evolution mechanism and regime shift crucial threshold of Lake Honghu wetland are studied. The results showed that the evolution of water quality in Lake Honghu from 1990 to 2020 tended to be summarized into five stages and three periods, showing a deteriorating trend. From 2011 to 2020, the Margalef, Shannon-Wiener, Simpson and Pielou index of aquatic plants in Lake Honghu had decreased by 32%, 59%, 60% and 46% respectively, especially after the flood disaster in 2016. The crucial period for regime shift of Lake Honghu wetland ecosystem is 2002 and 2011 and total phosphorus is the key driving factor. The threshold value of total phosphorus from clean water to turbid water is 0.092 mg/L, and that from turbid water to clean water is 0.051 mg/L. This study provides a reference for the estimation of the pollution reduction load into Lake Honghu, and guidance for the priority control strategy of nutrients in the ecological restoration.