Study On The Impact Of Onshore Wind Farm Developments On The Wintering Waterbirds And Their Conservation Strategies In The Coast Of Yangtze River Delta,China

Globally,climate change is one of the major challenges world is facing currently.Energy conservation and emission reduction,and the developing renewable energy are the key paths to cope with climate change.Wind energy has been developed rapidly in the world because of its advantage of clean and pollution-free.China has been the country with the largest total capacity of wind energy developments in the world since 2008.A large number of studies indicated that wind energy development will have variety of negative effects on birds,which falls into the direct and indirect effects.The direct effects include the collision risk caused by wind energy facilities;and indirect effects include the changes in the spatial and temporal distribution of birds,habitat loss,behavior changes and community structure changes result from wind energy development.Exploring the response of birds to wind farms and strategies for balancing the wind farm development and bird conservation are crucial.The Yangtze River Delta is the region with high economic development level,large population density,abundant wind resources and high energy demand in China.Wind farms in the coast of Yangtze River Delta are developing rapidly,and the capacity of wind farms in this region has reached 9,418.6 MW in 2019.Meanwhile,the coast of Yangtze River Delta is the important stopover and overwinter site along the East Asian-Australian Flyway,and more than millions of waterbirds stop and overwinter in this region every year.In this study,we selected the coast of Yangtze River Delta(covering from the Guanhe Estuary to the Yangtze River Estuary)as the study area,and did the surveys of waterbird communities,ducks(the dominant waterbird group)tracking and ducks' behavior observations in 2018-2021.Statistical methods include ANOVA,Generalized Linear Mixed Model,and Hierarchical Partitioning.From the perspective of taxonomic,functional and phylogenetic diversity of waterbird communities,distribution characteristics and habitat utilization of ducks,collision risk between ducks and wind farms,and the relationship between key waterbird habitats and wind farms,we qualified the impact of onshore wind farms and surrounding landscape structures on waterbirds.The main results are as follows:1 Waterbird community assembly in wind farm areas from functional and phylogenetic perspective.From December 2019 to February 2020,December 2020 to March 2021,the wintering waterbird diversity and landscape structure(Edge density of Aquaculture pond,farmland area,landscape compositional heterogeneity,and Normalized Difference Vegetation Index)of 53 study sites within 6 different levels of wind farm intensities in the coast of Yangtze River Delta were investigated and analyzed.The results showed that the taxonomic,functional and phylogenetic diversity of the wintering waterbird community were significantly different among the six wind farm intensities,and the wintering waterbird community was clustered in functional and phylogenetic,especially in the sites with the highest wind farm intensity(41-50).Environmental filtration leads to the waterbird communities assembly.There were no significant differences in landscape construction within 6 wind farm intensities.Results of the single-variable ordinary least squares regression and spatial auto regressive models showed that the taxonomic diversity and functional diversity of wintering waterbirds are significantly positively correlated with the normalized vegetation index,and significantly negatively correlated with the intensity of wind farm,landscape configuration heterogeneity,and the edge density of aquaculture ponds.Phylogenetic diversity of waterbirds was significantly correlated with the intensity of wind farms and the edge density of aquaculture ponds.The standardized effect size of functional and phylogenetic diversity was significantly positively correlated with landscape composition heterogeneity and farmland area.Results of hierarchical partitioning show that the wind farm intensity has highest independent explanation in explaining the waterbird species,functional and phylogenetic diversity.This study shows that wind farms and landscape structures dominate the waterbird community assembly jointly.It is suggested that the regions with low density of aquaculture ponds should be avoided in wind farm planning,and the number of wind turbines should be reduced to mitigate the impact on bird diversity.2 The dominant group's distribution and habitat use in response to onshore wind farms.From November 2018 to February 2019,November 2019 to January 2020,we conducted 7 duck surveys in 24 survey plots(3 habitats;artificial brackish marsh,paddy fields,and aquaculture ponds),and tracked 12 individual ducks using satellite tracking in Chongming Dongtan,Yangtze River Delta,China.Two-way ANOVA was applied to test ducks' abundance in three types of habitat in the site inside(IWF)and outside wind farm(OWF).The results showed that ducks' abundance in OWF was significantly higher than in IWF,and the ducks' abundance in the artificial brackish marsh was significantly higher than that in the aquaculture ponds and paddy fields.Based on 1,918 high-resolution satellite tracking records showed that the main habitat types of ducks were artificial brackish marsh and paddy fields during the day and night,respectively.Furthermore,grid-based analysis showed overlaps between ducks and wind farms were greater at night than during the day.According to resource selection functions,habitat use by wintering ducks was impacted by distance to water,land cover,human activity,and wind farm effects,and the variables predicted to have significant impacts on duck habitat use differed between day and night.Our study suggests that wintering ducks tend to avoid wind turbines at Chongming Dongtan,and landscape of paddy fields and artificial wetlands adjoining natural wetlands is crucial for wintering ducks.3 Collision risk between onshore wind farms and dominant group(ducks).From November 2018 to April 2019,November 2019 to January 2020,we recorded the duck's movements by combining 15 ducks' satellite tracking and 7 field surveys during dawn and dusk in the Yangtze River Delta,China.Based on 3,532high-resolution satellite tracking records from 15 ducks,it was found that distances between ducks' locations and nearest wind turbines in middle and later wintering periods were significantly higher than during early period.According to the collision risk analysis based on flight altitude,ducks inside wind farm tended to fly outside turbine rotor height range(45–135 m: between lowest and highest points the rotor tips)within 300 m from the dyke where the turbines were located,thus decreasing their collision risk.Observations of 544 ducks' behaviors during peak periods of movement(dawn and dusk)showed that ducks tended to fly below the minimum rotor tip height(< 45 m)when the turbines were rotating.These results suggest that ducks adopt behavioral avoidance strategies in response to wind farms.4 Relationship between key waterbird habitats and wind farms.From November 2019 to February 2020,November 2020 to March 2021,six field surveys were conducted on the waterbirds' species richness and abundance as well as habitat characteristics(upper tidal flat area,farmland area,and human activity)in 30 survey plots(15 river mouth area and 15 open coast area)in the Jiangsu coast of Yangtze River Delta.The results showed that the total species richness,total abundance,and each waterbird group's species richness and abundance in river mouth area were significantly higher than those in the open coast area.11 river mouth areas are defined as key waterbird habitats in this study.Total species richness,total abundance,and each waterbird group's species richness and abundance were significantly influenced by the upper tidal flats,which was the key habitat characteristics for waterbirds.Among the key waterbird habitats,Yipai River mouth,and the 300 m buffer of Yipai River mouth,in Xiangshui County were exposed by the highest wind farm intensity.It is recommended to manage the wind farm by developing the strategy of decommissioning or relocation to mitigate the impacts on birds.In conclusion,wind farms in the coast of Yangtze River Delta and the surrounding landscape structure dominate the construction of bird communities jointly.Distribution of ducks overlaps with wind farms,and habitat selection is significantly influenced by wind farms.Collision risk based on flight height is affected by wind farms presence and operational status.Discrepant exposure of wind farms exists around key waterbird habitats in the coast of Yangtze River Delta.It is suggested that key waterbird habitats and surrounding landscape of aquaculture pond and farmland should be avoided in the onshore wind farm planning in coastal wetlands,and areas with low edge density of aquaculture pond should be avoided.It is recommended to coordinate the decommissioning and/or relocation of wind farms in key bird habitats and the operation of wind turbines in the 0-300 m buffer of key bird habitats during the peak of duck activity by strategies of ecological compensation.