Diversity Of Waterbird Community Enhanced By Artificially Restoring Aquatic Vegetation At Shengjin Lake,China

The waterbird community is structured by environmental factors,eventually forming an organic complex through the interaction of various environmental factors.Changes in aquatic vegetation lead to differences in habitat characteristics and food resources,which could affect changes of waterbird community diversity in wetland directly or indirectly.In addition,the food abundance and availability,as well as the artificial disturbance are also important factors affecting the structure of waterbird community.Changes in foraging habitat affects the composition of waterbird foraging guilds,which in turn threating the stability of waterbird community structures.In recent years,in order to accelerate the restoration of wetlands,a largescale demonstration project of artificial vegetation restoration has been implemented in Shengjin Lake.The effect of restoration has greatly changed the local vegetation structure and characteristics.The change of vegetation would inevitably affect the waterbird community,as waterbirds have to depend on it for survival.Studying the influence of artificial vegetation restoration on waterbird community can help us to understand the succession of waterbird community and its response to environmental changes,and provide positive significance for the protection of wetland waterbirds.In this study,four types of waterbird habitats in the buffer and the experimental zone of Shengjin Lake National Nature Reserve were selected as the research area.Through the survey of waterbird assemblage,plant resource allocation and habitat characteristics,the differences among the study sites were clarified.Further the diversity of waterbird community and seasonal dynamic changes between sites were analyzed,and the impact of vegetation changes on the diversity of waterbird community were explored.The main research results are as follows:1.The waterbird richness at Shengjin Lake is relatively rich.A total of 37 species belonging to 13 families and 6 orders were recorded in four types of waterbird habitats in the buffer zone and experimental zones between August 2018 and September 2019.Thirty species belonging to 11 families and 6 orders were counted in the aquatic vegetation restoration area,including spot-billed duck,common teal,common moorhen and Eurasian spoonbill as the advantages species,observed large numbers of ducks foraging in deep water areas.A total of 24 species belonging to 9 families and 6 orders were counted in the Euryale ferox planting area,with the advantages being little grebe,spot-billed duck,common teal,common moorhen,and northern lapwing.Thirteen species belonging to 7 families and 5 orders were counted in the rice planting area,with bean goose and hooded crane as the dominant species.Fourteen species belonging to 6 families and 5 orders were counted in the freshwater aquaculture area,with the advantages being little grebe,spot-billed duck,common moorhen and the common coot.2.Seasonal changes in the waterbird communities in four study areas showed that the species and density of waterbirds in the aquatic vegetation restoration area were the highest in each of the four seasons.Except for summer,when the highest waterbird density in the Euryale ferox planting area was observed,the other three study areas had the highest waterbird density in winter.Comparison of species in each study area during winter,autumn and summer: the aquatic vegetation restoration area > the Euryale ferox planting area > the freshwater aquaculture area > the rice planting area;comparison of species in each study area during spring: the aquatic vegetation restoration area = the Euryale ferox planting area > the freshwater aquaculture area > the rice planting area.The evenness index is higher than that of the aquatic vegetation restoration areas and the Euryale ferox planting area in the rice planting area and the freshwater aquaculture area,while the seasonal differences of waterbird species in the four study areas are not obvious.3.Through the implementation of the aquatic vegetation restoration project,the restoration effect of various aquatic vegetation in aquatic vegetation restoration area was remarkable.In four study areas,a one-way ANOVA of seven habitat factors for the two winter periods 2017–2018 and 2018–2019 found that there was no significant difference in habitat factors in the 2018–2019 winter period compared to the 7 habitat factors of the Euryale ferox planting area,the freshwater aquaculture area,the rice planting area in the 2017–2018 winter period(P > 0.05).There was a significant increase in the area of all types of vegetation in the aquatic vegetation restoration area(proportion of the area of emerging vegetation,P < 0.05;the proportion of submerged vegetation area,P < 0.05;the proportion of floating vegetation area,P < 0.05),and the proportion of total mudflat area increased to 23.41%.4.The proportion of aquatic vegetation area and beach area are the key habitat factors affecting the structure of waterbird communities in winter.Pearson correlation indicates that the waterbird species and density were significantly positive correlation with floating,submerged,mudflat areas,and there was significantly negative correlation between waterbird species and disturbance level;the diversity index was negatively correlated with water depth,and there was significantly positive correlation between diversity index of waterbird and the proportion of emerging vegetation area and open water area;the evenness index was positively correlated with the proportion of water depth and surface area.5.The increasing trend of waterbird species is greater than the loss trend of species in the aquatic vegetation restoration area.The absolute value of Temporal Beta-diversity Index(TBI)of the restored aquatic vegetation area was the highest,while the species gains(C)was significantly greater than the species losses(B).At the foraging guild level,there was a significant increase in species number of wintering waterbirds from three foraging guilds in the restored aquatic vegetation area in the wintering period of 2018-2019 compared to 2017-2018(G3: Granivore guild;G4: Invertebrate guild;G5: Piscivore guild).The restoration of aquatic vegetation mainly increased the number of Anatidae species,including ruddy shelduck,common teal,common mallard,spot-billed duck,and common pochard.