Study On Population Dynamics And Key Habitat Drivers Of Six Typical Waterfowl Species In Chenhu Wetland Nature Reserve

Exogenous factors such as land-use type change and human disturbance have seriously threatened the living conditions of animals and plants.As an important ecological barrier to maintain biodiversity,wetland can provide rich means of production for a variety of animals and plants such as waterfowl.However,there were still many challenges to scientifically and accurately monitor the current situation and trend of wetland environmental changes and clarify the habitat drivers of waterfowl population dynamics.There were abundant landscape elements in Chenhu Wetland Nature Reserve,which could provide an excellent habitat for waterfowl.However,there were some problems,such as habitat degradation,landscape fragmentation and enhancement of human disturbance.In order to explore the change law of waterfowl population under the influence of exogenous factors in Chenhu Wetland Nature Reserve,more targeted habitat restoration strategies and waterfowl protection measures could be put forward.In this study,the ecological types,feeding habits,habitat and protection levels of different waterfowls were comprehensively considered,and six typical waterfowls,including oriental stork,black stork,common crane,bean goose,falcated duck and great grested grebe,were selected as the study object in this study.Based on the survey data of waterfowl,water level,water quality,engineering measuresand land-use type changes from 2005 to 2020,combined with the field land-use type survey and wetland vegetation survey,the key habitat drivers of six typical waterfowl population dynamics were explored by using visual interpretation,landscape pattern analysis and Spearman rank correlation methods.It is hoped that targeted protection suggestions could be put forward for different types of waterfowl.The main results of this study are as follows:(1)From 2005 to 2009,the populations of oriental stork and black stork were small and had not been observed for many years.The number of common crane population fluctuated greatly.Taking 2016 as the boundary,the volatility of its population firstly decreased and then increased.There were a large number of bean geese.Taking 2013 as the boundary,the volatility of bean geese population firstly increased and then decreased.The populations of falcated duck and great grested grebe were relatively large,which showed a fluctuating and increasing trend on the whole.(2)According to the survey results in 2021,there were 270 species of wetland plants in Chenhu Wetland Nature Reserve,belonging to 65 families and 182 genera.Among them,the areas of reed community and carex rafflesiana community were the largest,859.78hm~2 and455.13hm~2,respectively.(3)From 2005 to 2020,the change of land-use types in Chenhu wetland nature reserve could be divided into two stages.From 2005 to 2016,the areas of shallow water areas,deep water areas,rivers and tidal flats were in the state of transferred out as a whole.In addition to the mutual transformation of lakes,rivers and tidal flats caused by the interannual change of water level,most shallow water areas,deep water areas,rivers and various tidal flats were transformed into aquaculture ponds and lotus root fields/paddy fields.From 2017 to 2020,affected by the policies of“Returning Farmland to Lake”and“Returning Livestock to Lake”,the Artificial Wetland was gradually transformed into Natural Wetland.In recent 16 years,the dominant landscape in Chenhu Wetland Reserve has changed from Artificial Wetland to Natural Wetland,and the degree of landscape fragmentation has decreased.(4)Oriental stork was alert and was most affected by disturbing and protective engineering measures,followed by black stork and bean geese.Landscape pattern dynamics was an important factor affecting six typical waterfowl species.Among them,the expansion of settlements and roads was the key habitat drivers for the decline of the population of oriental stork,common crane and great grested grebe.Limited by the habitat,the area,quantity and density of lakes were the primary factors affecting the population dynamics of falcated duck and great grested grebe,followed by the mudflat and cultivated land.The population of oriental stork and black stork was limited by the area and aggregation of lotus root field/paddy field,cultivated land,forest land,the area and and aggregation degree of settlements and roads.The water quality of Zhangjia lake had a significant negative impact on the population of bean geese,but in this study,the impact of water level and water quality on the population dynamics of the other five typical waterfowls was not significant.There are some habitat restoration strategies based on six typical waterfowl key habitat drivers.(1)We should increase habitat diversity and create a large number of open water habitats with small area and sheltered by tall plant communities such as reed and cattail.(2)According to the migration time of different waterfowl,the water level of the lake should be adjusted reasonably,and the exposure time and range of carex rafflesiana mudflats and other herb mudflats should be controlled.(3)It should be forbidden to carry out large-scale construction in the core area and buffer zone,and the construction time was regulated to avoid the overwintering period.(4)Habitat restoration measures such as enclosing carex rafflesiana and reed,and restoring aquatic animals and plants.(5)Through ecological compensation,farmers should be guided to adjust the planting structure of farmland around wetlands,increase the planting area of wheat and corn,and provide more abundant food resources for bean goose and common crane.