Study On The Habitat Suitability Of Dominant Andkey Waterbird Species Wintering In Shengjin Lake

Wetland is a transitional zone between land and water.It is one of the most biodiverse ecosystems on earth.It has such important functions as degrading pollution,purifying water,stabilizing water supply,preventing floods and maintaining ecosystem balance.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.At the same time,the degradation and loss of natural wetlands in Shengjin Lake also have an important impact on wintering waterfowls,and it is urgent to evaluate the habitat suitability of wintering waterfowls.In this paper,Shengjin Lake Nature Reserve as a research site,(1)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.(2)In the wintering season from 2015 to 2017,30 survey sampling sites were set up along the periphery of Shengjin Lake.Field surveys were conducted on the spatial distribution of waterbirds overwintering and their influencing factors.The general linear models were used to analyze the effects of each factor on the geese habitat and construct the habitat suitability model.The main findings are as follows:(1)Results showed that water level in Shengjin Lake showed obviously seasonal fluctuations.As the water level rise,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.(2)NDVI and mudflat area were positively correlated with the size of the population of White-fronted Goose(Anser albifrons);the grassland and mudflat area was positively correlated with the population size of Bean goose(A.fabalis).For both geese,the grassland and mudflats in the Shengjin Lake zone have high habitat suitability.The suitable habitat of Oriental White Stork(Ciconia boyciana)is the shallow water area in the northwest of Shengjin Lake.Hooded Crane(Grus monacha),due to its diet characteristics,is suitable for habitat for lakeside tidal flats and paddy fields along Yang Etou to She Gan and Tong Xinwei.The results of this study show the spatial pattern of habitat suitability of four waterbirds overwintered in Shengjin Lake,revealing the environmental factors that affect their habitat utilization and provide a scientific basis for the effective management and protection of wintering waterfowls.Simultaneously,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.