Study On The Relationship Between Diversity Of Wintering Waterbirds And Environmental Factors At Caizi Lake

As an indispensable part of the wetland ecosystem,waterbirds play an irreplaceable role in maintaining the stability of the wetland ecosystem.Waterbirds are sensitive to changes in wetland environmental factors,which can directly or indirectly affect the species,quantity and distribution of waterbirds by changing habitat characteristics and food resources at different spatial scales.In the next few years,the Caizi Lake wetland will be used as a water transfer channel for the "Diversion from the Yangtze River to the Huaihe River" project,and rising water levels will lead to changes in the habitat.Therefore,it is of great significance to study the relationship between wintering waterbirds and environmental factors at Caizi Lake for guiding the scientific management of wetland.From October 2019 to January 2020,and from October 2020 to January 2021,the direct observation method was used to monthly investigate the wintering waterbirds at Caizi Lake.On this basis,using correlation analysis,multiple stepwise regression and spatial statistics were used to analyze the relationship between the temporal and spatial dynamics of waterbirds and environmental factors.The main research results are as follows:1.A total of 53 species,12 families,7 orders,were found at Caizi Lake.A total of 88,630 birds,44 species,12 families,7 orders,were investigated in 2019?2020.The number of waterbirds showed a trend of increasing first and then stabilizing,and the diversity index showed a trend of first decreasing and then increasing.A total of 117625 birds,45 species,12 families,7 orders,were investigated in 2019?2020.The number of waterbirds showed a trend of increasing first and then deincreasing,and the diversity index showed a trend of first decreasing,then increasing and then deincreasing.The number of waterbirds from October to December of 2020 is less than that from October to December of 2019,and the number of waterbords in January 2021 is significantly higher than that in January 2020.During the two wintering periods,there were differences in the species and quantity of waterbirds among the three lakes at Caizi Lake.The abundance and species of waterbirds in Baitu Lake and Caizi Lake was higher than that in Xizi Lake.2.It was found that water level,temperature and patch density are the key environmental factors that affect the time dynamics of wintering waterbirds at lake scale.The water level can affect the temporal dynamics of the total amount of waterbirds and sedge-eating waterbirds by affecting the outcropping of grass and mudflat in the wetland.In the early wintering period,the long-term maintenance of the high water level in the lake greatly reduces the suitable habitat for the zoobenthos-eating waterbirds,forcing the migratory zoobenthos-eating waterbirds to leave the original habitat and go to other lakes for wintering.With the decrease of water level,the exposure of tidal-flat area and increased the habitat area of rhizome-eating waterbirds,so that there was a significant negative correlation between water level and rhizome-eating waterbirds(R=-0.850,P=0.004).With the decrease of temperature,the total amount of waterbirds in the lake shows an upward trend,and there is a significant negative correlation between the total amount of waterbirds and the minimum temperature(R=-0.717,P=0.030),and the effect of temperature on waterbirds will be more obvious for sedge-eating waterbird(R=-0.833,P=0.005).With the increase of wetland patch density,along with the increase of wetland landscape fragmentation,habitat islets appeared in the lake,which provided suitable habitat and food resources for seed-feeding waterbirds.3.The spatial distribution characteristics of waterbirds will vary with the food resources for their own survival need.Habitat factors and human disturbance were the main factors affecting the spatial distribution of waterbirds.The distribution patterns of rhizome-eating waterbirds and sedge-eating waterbirds revealed significantly positive autocorrelations and clustered distributions(P<0.05,I>0),while those of seed-eating waterbirds,zoobenthos-eating waterbirds and fish-eating waterbirds showed non-autocorrelational and random distributions(P>0.05).Fish-eating waterbirds tended to choose the open water which has large areas,while the mudflats exposed by the wetland attracted Zoobenthos-eating waterbirds.The degradation of submerged vegetation led to the aggregation and distribution of Rhizome-eating waterbirds in farmland and grassland habitats.The quantity of sedge-eating waterbirds increased significantly because of the formation of vast grasslands.Seed-eating waterbirds were often distributed in low-vegetation and open water habitats.The distance to the nearest settlement or to the road had significant effects on tuber eaters,sedge eaters,seed eaters,and fish eaters(P<0.05).