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Small- and medium-sized rivers are facing a serious degradation of ecological function in water resource-scarce regions of Northern China. Reservoir ecological operation can restore the damaged river ecological environment. Research on reservoir ecological operation and watershed management of urban rivers is limited in cold regions of middle and high latitudes. In this paper, the urban section of the Yitong River was selected as the research object in Changchun, Northern China. The total ecological water demand and reservoir operation water (79.35 × 106 m3 and 15.52 × 106 m3, respectively) were calculated by the ecological water demand method, and a reservoir operation scheme was established to restore the ecological function of the urban section of the river. To examine the scientific basis and rationality of the operation scheme, the water quality of the river and physical habitat after carrying out the scheme were simulated by the MIKE 11 one-dimensional hydrodynamic-water quality model and the Physical Habitat Simulation Model (PHABSIM). The results indicate that the implementation of the operation scheme can improve the ecological environment of the urban section of the Yitong River. A reform scheme was proposed for the management of the Yitong River Basin based on the problems in the process of carrying out the operation schemes, including clarifying department responsibility, improving laws and regulations, strengthening service management, and enhancing public participation.

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Aims: Siberian crane (Grus leucogeranus) is a migratory, endangered species that uses the Songnen Plain as a main stopover area. Traditionally a wetland species, today most populations of Siberian cranes feed and rest during migratory stopovers in fields of corn (Zea mays). By examining the causes of this change in stopover habitat use, we can provide better protection for and potentially recovery of this declining species. Methods: We recorded the numbers of Siberian cranes and both food resource and habitat usage on stopover sites on the Songnen Plain from September 2020 to November 2021 in the study area. These data were collected and analyzed using Google Earth, ArcGIS 10.7. Results: Of the total number of Siberian cranes we observed, 72.7% were feeding on farmland, which was 2.66 times more than that of wetland habitats. Farmland has become the main feeding habitat for Siberian cranes. The total energy provided by farmland was 1.24-2.79 times as much as that provided by wetlands based on different harvesting methods, and the energy intake of Siberian cranes in farmland was about 1.56 times that of wetland. The daily feeding budget of Siberian cranes in farmland was 53.5% of their total time, which was 1.67 times more than that in wetlands. The feeding

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