Birds In Urban River Corridor Under Different Landscape Patterns Study On Diversity Differences And Their Causes

As an important indicator species to quantify the health of urban ecosystem,the survival and reproduction of bird community depend on the habitat environment,and the environmental factors are closely related to urban birds.Urban river corridor is an important part of urban ecosystem,which is both habitat and migration channel for birds.Based on the structural characteristics of urban river corridors,this study investigated the differences of bird diversity in urban river corridors,explored its causes,and clarified the key factors affecting bird diversity.The study selected Nanfei River in Hefei City as the research object,600 m on both sides of the middle line of the river as the research scope,using the land cover data,it was divided into five categories,such as farmland,water,forest,grassland and building.According to the land cover ratio,the habitats were divided into four types: natural area,built-up area,industrial area and farmland area.A total of 21 plots were selected to set bird survey transect lines,sites and plant survey quadrats.The relationship between urban bird diversity and landscape structure characteristics of urban river corridor was explored by quantifying land cover pattern with 100 m on each side of bird survey transits.Among the findings:1)According to the investigation of land cover pattern and vegetation structure in 21 sample plots,buildings and farmland cover are the main types of land cover.In the land cover,there were 8 transect lines with high forest cover area.Farmland and buildings accounted for relatively high 4 each;Water area and grassland accounted for 1 each.The landscape diversity index was between 0.18 and 1.55.The highest degree of grassland cover fragmentation was 75.10,and the degree of building and farmland patch fragmentation was low(8.17;11.09).100 species of 55 families and 93 genera were measured in the quadrangles,including 3365 trees,555 shrubs,1474.1 square meters of hedgerows and 2879.8 square meters of herbaceous ground cover.The tree diversity index ranged from 0.38 to 1.98,and the shrub richness index ranged from 0.53 to 1.81.The number of quadrat trees in various plots ranged from 70 to 300,the average height of trees ranged from 6.25 to 18.3m,the average DBH ranged from 52.5-151.5cm,and the average crown width ranged from 2.75 to 6.8m.2)A total of 5225 birds of 11 orders,32 families and 70 species were recorded in 21 transect lines in the river corridor plot of Nanfei River during the summer and winter investigation periods.The difference in order species composition between summer and winter was mainly manifested in winter and summer migrant birds.Meanwhile,the diversity index in summer(3.15)was higher than that in winter(2.97),and the evenness index in winter was higher than that in summer(0.77).Species similarity values between the pairs of 21 plots ranged from 0.345-0.824,and there were significant differences in bird richness,abundance,Shanno diversity index and Pielou evenness index among the four habitat types of natural area,built-up area,industrial area and farmland area(p < 0.05).The highest number of birds was 1515 in the built-up area(BD).The highest richness was 43 species in industrial zone(IDL).Agricultural area(RL)had the highest diversity and evenness index(2.97;0.86).3)This study concluded that land cover pattern,vegetation composition structure and environmental characteristics in urban river corridor landscape structure had different degrees of influence on bird diversity index,and natural area(NT)habitat and built-up area(BD)habitat were high quality bird habitat.The factors of landscape characteristics were divided into four aspects: farmland,water area,forest land cover and landscape diversity index.Vegetation characteristics can be summarized into three aspects: tree richness,diversity and shrub richness.The environmental characteristic factors can be attributed to three aspects: plot area,human disturbance and landscape shape index.Stepwise regression analysis showed that tree richness,tree diversity,farmland cover area proportion,landscape diversity index,water area proportion,plot area,human disturbance,shrub richness and landscape shape index were important factors affecting bird diversity difference in urban river corridor.The regression equations for predicting bird richness,abundance,Shannon diversity index and Pielou evenness index are obtained.Based on the above results,in order to better protect bird diversity in the city and give full play to the role of river corridor in the ecosystem,the boundary of the plot and the density of grassland and grassland between the surrounding areas should be enhanced in the planning and construction of urban river corridor.At the same time,the proportion of woodland and water cover area,canopy width and cover area of woodland should be increased,so as to avoid the unitary vegetation structure and provide more suitable habitat and food source for birds to survive and reproduce.