Abstract: Landscape patterns in seasonally inundated lake wetlands change significantly with the water level fluctuations. Shengjin Lake is a typical Yangtze-connected shallow-water lake, providing important staging and wintering habitats for waterbirds migrating along the East Asian-Australasian Flyway. The seasonally water-level-driven landscape changes may greatly impact wintering waterbirds in the lake. We conducted a supervised classification on Landsat images acquired in recent years using a maximum likelihood classifier (MLC) to quantify landscape patterns under different water levels. The relationship between water level and land-cover areas, as well as landscape indices, was investigated. Results showed that water level in Shengjin Lake showed obviously seasonal fluctuations. As the water level rose, area of open water increased, while the areas of grassland and mudflats decreased. Diversity and evenness of land-covers were also negatively correlated with the water level. Grassland and mudflats were mostly found in estuarine area in the upper and lower lake in winter, providing abundant food resources for diverse wintering waterbirds. However, the water level was still high for aquaculture during the early stage of the wintering season, resulting in limited grassland and mudflats exposed for waterbirds. Based on our findings, we suggest stepwise water recession plans in Shengjin Lake, allowing diverse habitats to be exposed gradually to provide essential foraging grounds for different waterbirds.

Key words: Shengjin Lake, water level, landscape pattern, wetland degradation