Bird Community Structure And Habitat Suitability Assessment In The Northern Experimental Area Of Yancheng National Nature Reserve,Jiangsu

The northern experimental area of Yancheng Nature Reserve is located in the coastal area of Jiangsu Province.Its unique geographical location and the special natural environment from environmental evolution make the place to be an important area to rest or overwinter for birds on East Asia-Australia path,which is one of the global migration channels.Along with the change of wetland utilization,the development along the beach has been increasingly strengthened.The number of construction projects in the northern experimental area of reserve has been increasing,and human activities such as aquaculture,salt industry,reclamation,port construction,and wind farms have been concentrated,which create tremendous pressure for the habitat of birds.Yancheng Nature Reserve has recently attracted the attention of many scholars because it is an important habitat for rare and endangered birds such as Grus japonensis to survive and reproduce.Researches mainly focus on the status and changes of rare birds,the patterns of bird communities in wintering period and the impact of wind farms on birds.In this study,the spatial and temporal pattern of bird community structure in the northern experimental area of Yancheng Nature Reserve was studied based on different habitat types and seasons.The establishment of habitat suitability model on five waterfowl species which based on quantitative indicators was used to evaluate the status of habitat suitability and to analyze the major reason of habitat loss and degradation.These can provide scientific basis for maintaining the bird diversity and the stability of the ecosystem within the reserve.Moreover,effective and reasonable implementation for management and protection procedures as well as the suggestions for the design and plan of coastal construction can also be given.The main results of this study are as follows.(1)There are 67 bird species from 12 orders,27 families were recorded from field surveys,of which 47 were waterfowl,accounting for 71.2%.The major floristic composition was palaearctic species and the residue type was dominated by migratory birds,accounting for 59.7%of the total,and most of them were summer migratory birds.The dominant species of birds in study area were Passer domesticus,Calidris ruficollis and Calidris temminckii.Five species of national key protected animals are Ciconia boyciana,Grus monacha,Grus grus,Falco tinnunculus and Falco subbuteo.(2)Under the support of 3S technology,a combination of supervised and unsupervised classification methods,supplemented by manual visual interpretation,was used in this study.Bird habitat classification map in study area was obtained from this.Combined with historical research data,habitat characteristics,feeding habits and status of activities,the habitat was divided into shallow sea waters,salt marshes,artificial wetlands,reeds,farmlands&woodlands,and human activity areas.(3)Through the analysis and researches on the distribution of different species of birds in different habitats,it was found that Laridae were mainly concentrated in shallow sea waters,and the distribution in salt marshes and artificial wetlands were similar,slightly inferior to shallow seawater.Ardeidae were mainly distributed in salt marshes and constructed wetlands.Charadriiformes were widely distributed in salt marsh habitats,which the ratio was up to 81.6%.Anseriformes,Gruidae and Ciconiidae were most in artificial wetlands.Passeriformes were mainly selected to inhabit in human activity areas,farmlands&woodlands and reeds.(4)The bird diversity showed that the artificial wetlands were the highest in different habitat types,and the human activity areas were the lowest,while the evenness index was the largest in the shallow sea waters and the smallest in human activity areas.The regression analysis showed that there was a significant negative correlation between evenness index and human disturbance(y=1.883x+1.738,R~2=0.903,P<0.05).The highest similarity index among different habitat types was between salt marshes and artificial wetlands,which the value was 0.565.(5)Bird migration is the major reason of significant seasonal changes of bird community structure in study area.Bird diversity in artificial wetlands and salt marshes were generally higher than in other habitat types.The seasonal trend showed autumn>spring>winter>summer,which was consistent with the seasonal changes in overall community structure of birds.Bird diversity index in shallow sea waters was highest in winter.The highest and lowest value of bird diversity index in reeds was in winter and summer,respectively.The diversity index of human activity areas and farmlands&woodlands changed smoothly during the four seasons,with no significant fluctuations.The similarity between different seasons was highest between spring and autumn,and lowest between summer and winter.(6)The assessment factors of natural geography and human activities were selected to establish a suitability assessment model of waterfowls in the northern experimental area of Yancheng Nature Reserve.The analysis results indicated that the overall habitat was in a good level,and the study area was dominated by more suitable grades.Habitats with unsuitable grades were mainly distributed on roads and its surrounding area,indicating that human activities were still the major reason of habitat loss and degradation.