Zhang Siqi, a scientific staff member, marks the plant sample in Dongting Lake area, central China's Hunan Province, Oct. 24, 2018. Collecting soil in spring, testing lake water in summer, investigating plants in autumn and observing migrant birds in winter outlined nearly ten years of seasonal cycle daily life of nameless scientific researchers in the Dongting Lake area. They have worked hard to supply solutions to protection of the environment and biological diversity here. The scientific researchers from the Chinese Academy of Sciences (CAS) were praised as the doctors of Dongting Lake wetland. In order to supply scientific support for ecological remediation of Dongting Lake, the CAS established an observation and research center in Dongting Lake wetland. As the second-largest freshwater lake in China, Dongting Lake played an important role in maintaining ecological balance of the Yangtze River valley and also was an important habitat for migrant birds, milu deer, finless porpoise and etc. The ecology system of Dongting Lake faced environmental deterioration once upon a time due to various reasons, and had been improved year by year due to measures taken by local government. According to an investigation in January 2018, over 226,000 migrant birds spent the winter in Dongting Lake, up 23 percent from a year earlier. (Xinhua/Zhang Xiaoyu)