Past Environmental Changes and Management Suggestions for Lakes in the Yangtze River Economic Belt

Lakes in the Yangtze River Economic Belt are mainly distributed in the Hengduan Mountain area in Southwest China and the flood plain area of the Yangtze-Huaihe River Basin in East China. The high spatial variability of natural environment and economic development have rendered the ecological and environmental problems of these lakes. Comprehensive improvement of the lake environment and their ecological states are important for regional development. In the absence of long-term monitoring data, past environmental changes based on lake sediments, also termed as paleolimnological studies, can provide historical information for the protection and restoration of these lakes. This study revealed better water quality in alpine lakes than low-altitude ones in southwest China, while the worst water quality in the shallow lakes in the Jianghuai region. Furthermore, based on paleolimnological analysis, this study provided a long-term perspective to reveal the evolution characteristics and the mechanisms responding to the changes in climate, hydrology and nutrition in different lakes of the two areas in the past century. Such research also elucidated the reasons of the lake degradation in recent years, and exhibited the advantage of paleolimnological studies in defining reference conditions for ecosystem restoration, management evaluation, community structure optimization during aquatic vegetation restoration, early warning signals of ecosystem critical transition, and ecological safety assessment. Aiming at above environmental problems faced by lakes in different regions, the study put forward several targeted measures for their protection and restoration.