Bird Community Structure And Its Relationships With Environmental Factors In Tiantong National Forest Park,Zhejiang Province

The study of the relationship between the distribution characteristics of birds and environmental factors is a hot topic of scientists in recent years,which helps to understand the important environmental factors of bird distribution,thus providing a theoretical basis for bird protection and environmental construction.In order to fully understand the relationship between bird distribution and environmental factors in Tiantong National Forest Park,from July 2017 to June 2018,the bird community in Tiantong National Forest Park was investigated and selected from 6 sample belts.Six different habitats were used to analyze the composition,community structure and community similarity of bird communities in habitats.The relationship between birds and environmental factors in Tiantong area was explored by using canonical correspondence analysis and BIOENV analysis.Key environmental factors affecting the distribution of birds in Tiantong area;cluster analysis is used to classify bird guilds according to the dependence of birds on forests,and the differences of environmental factors selection among birds within the guild are compared;and from the perspective of niche the difference between the same guild's choice of environmental factors in the model correspondence were analysed;the relsults are as follows: 1.Bird community structureA total of 87 species of birds were recorded,belonging to 11 orders and 33 families.According to the ecological guild: it is divided into songbirds,land birds,poultry,waders,raptors,poultry,and poultry.Among them,songbirds account for the largest variety,accounting for 78% of all species.According to the type of residence: there are 48 species of resident birds,accounting for 55% of the species of birds;24 species of migratory birds,including 19 species of winter migratory birds,accounting for 22% of bird species,5 species of summer migratory birds,14 species of brigade birds,and 1 species of fascinating birds.From the perspective of the fauna: 43 species in the Eastern Ocean,accounting for about 50% of the total species of birds;36 species of birds in the Palaearctic,accounting for 41% of the species of birds;8 species of widespread species.According to the composition of food,the number of omnivorous birds is the highest,accounting for 38%;followed by insectivores,the number is 32%;carnivorous birds,the number is 17%;the number of carnivorous birds,breeding birds,and grazing birds accounted for 13%.The research in this paper shows that the bird diversity index and richness index are the highest in the wintering period from the perspective of different seasons in birds.From the perspective of habitat,the bird diversity index is the highest in bamboo forest and the richness index is the highest in broad-leaved forest.The similarity coefficient was used to compare the similarity between different habitats.The results showed that the broad-leaved forest and coniferous and broad-leaved mixed forest had the highest similarity,the value was 0.680,the coniferous and broad-leaved mixed forest and farmland were the second,and the broad-leaved forest and wetland had the lowest similarity.Compared with different habitats in the same season,the abundance and diversity of birds are relatively abundant in broad-leaved forests,coniferous and broad-leaved mixed forests,and bamboo forests;Compared with different seasons in the same habitat,the bird richness is relatively abundant during the wintering and autumn migration periods.2.Analysis of birds-environmental factors in Tiantong National Forest ParkThis study used BIOENV analysis and Canonical Correspondence Analysis(CCA)to explore key environmental factors affecting the distribution of birds in the Tiantong area.In bird ecology,the BIOENV analysis method was used for the first time to analyze the relationship between bird distribution and environmental factor time.Through the correlation analysis between BIOENV abundance matrix and environmental factor matrix,the most closely related environmental factor subsets in spring migration period and bird distribution are tree height,tree diameter,tree cover,and herbaceous shrub coverage.The correlation coefficient is 0.534;the subset of environmental factors most closely related to bird distribution during breeding period is tree height,tree diameter,and tree coverage,with a correlation coefficient of 0.770;the key environmental factor subsets affecting bird distribution during autumn migration are tree diameter,The height of arbor,the coverage of arbor and the coverage of herbaceous shrubs were as high as 0.830.The key environmental factors affecting the distribution of birds during wintering were tree diameter,tree height and arbor coverage,and the correlation coefficient was 0.396.Canonical correspondence analysis establishes two matrices of habitat-species,habitat-environmental factors,and finally analyzes the relationship between species and environmental factors.In the research results of this paper,the positive correlation coefficient is the height of trees and the coverage of trees.The diameter of the tree and the diameter of the herbaceous shrub are basically the same as those of BIOENV.The canonical correspondence analysis can analyze the positively related environmental factors,and can also analyze the negative correlation environmental factors.In the results of this study,human direct interference is a negative correlation environmental factor that affects the distribution of most birds,but a relatively positive environmental factor for a small number of more loved ones.Among the disturbance factors,the distance from the artificial indirect interference factor has little effect on the bird distribution.The BIOENV analysis and the Canonical Correspondence Analysis(CCA)are basically consistent,indicating that the results of the two analyses are accurate and reliable.The results of the BIOENV analysis can more directly show the positive correlation between environmental factors and birds.The results of the Canonical Correlation Analysis(CCA)show the negative environmental correlation and weak correlation of environmental factors while showing the key environmental factors of bird distribution,which can make up for the defects of BIOENV.3.Analysis on the Selection of Environmental Factors by Birds in the Same GuildUsing the most distant neighbor cluster analysis method,according to the dependence of birds on forests,the birds are divided into forest-dependent species,forest generalists and non-forest species,and non-forest birds are also classified as completely non-forest birds and incomplete non-forest birds based on field observations.The group analysis found that the same species of birds were in different forestdependent groups at different times.Such as Chestnut Bulbul,in the spring migration period,autumn migration period and overwintering period,all belong to forestdependent species,but in the reproduction period they belong to non-forest birds.In order to explore whether there is consistency in the selection of environmental factors for the same guild of birds,the results of the corresponding bird species in the same bird guild are compared with the results of the model correspondence analysis.The results of the study showed that birds in the same guild did not have strict consistency in the selection of environmental factors.For example,in the forest-dependent species,the grey-cheeked fulvetta,the Chestnut Bulbul,and the Black-throated Tit are belong to the same guild in the spring relocation period,but in the CCA sorting chart,the greycheeked fulvetta is more inclined to the height of the pro-arbor,and the Black-throated Tit and the Chestnut Bulbul are more inclined to the degree of concealment.4.Niche analysis of the same group of birds in canonical correspondence analysisThe Levins index method was used to determine the niche breadth of birds in the habitat type dimension.The niche overlap was calculated by the niche overlap index proposed by Cowll and Futuyma.The niche analysis of the birds in the same group in the canonical correspondence analysis was conducted to investigate whether there was a high niche overlap between the birds in the same group.The results of the analysis showed that the birds in the same group did not show absolute high overlap values,that is,the variation was large,such as White Wagtail and Grey Wagtail,which were close to each other on the CCA sorting map and belonged to the same group of birds.The choice of environmental factors is very similar,but the niche overlap values are low.