Simulation Study On The Biological Genetic Diversity Impacted By Landscape Pattern Of Zixing City

In recent years,due to the rapid development of urbanization,frequent human activities,reduced habitat area of species,and increased fragmentation of habitats,these factors have subtly changed the urban landscape pattern and living environment.Making landscape patterns and biodiversity Research on the relationship has received much attention.This paper takes ecological county-Zixing City and Zixing City National Wetland Park-Dongjiang Lake as the research object,and selects the protected species of Zixing City-the habitat of the great egret and the great egret to survive-the reed wetland as the research sample.The landscape genetics,landscape ecology principles and methods,remote sensing,GIS technology and landscape genetic simulation model were used to analyze the changes of biological genetic diversity under different landscape pattern of Zixing City and Dongjiang Lake.Exploring the reasons for the change of landscape pattern on zixing City and Dongjiang Lake Wetland Park in the past 16 years.Putting forward the optimization scheme of landscape ecological pattern of Zixing City,and the feasibility of the optimization scheme was proved by landscape genetic simulation.The results of the study will reveal the changes in landscape patterns and changes in biodiversity caused by increased urbanization and frequent human activities,Which will provide a new theoretical basis and basis for urban ecological construction planning and biodiversity conservation.The main findings of the paper are as follows:(1)By comparing the landscape pattern in 2003 and 2018,it is found that the area of construction land and cultivated land in Zixing City has increased significantly in 2018,and the degree of fragmentation has increased,the area of wetlands and forest land is gradually decreasing.The plaque density of the wetland increased from 0.0047 to 0.1505,the plaque density of the forest increased from 2.3172 to 3.9901,and the overall plaque density increased from 3.0553 to 6.7147.Based on the above data,the landscape pattern of Zixing City is fragmented.(2)Based on the 2017 landscape pattern,the minimum resistance model of Zixing City and minimum cost path of biological migration were constructed.According to the research results,making the reasonable landscape pattern optimization scheme and generate landscape ecological security pattern.The optimized landscape pattern simulation increased the forest area by 20584.6 hectares and the wetland area by 3790 hectares.Using landscape genetic simulation model to analyze three landscape pattern:under the landscape pattern in 2003,the difference between the Great Egret Ho(observed heterozygosity)and He(expected heterozygosity)is small,the Mantel r value is between 0-0.15,and the Fis statistic value is not obvious.Overall,the value are lower,It shows that the genetic diversity of the population under the landscape pattern in 2003 is relatively rich.In 2018,the difference between the observed heterozygosity and the expected heterozygosity increased significantly,the Mantel r value increased significantly.The rising rate between the 0-100 generations was the fastest,the 100-500 generation had no change and remained within the range of 0.5-0.6.The value of Fis changes significantly,the value shows an increasing trend compare with 2003.Which explain the landscape pattern has had an impact on biological genetic diversity in 2018 and is unfavorable.Through the optimized landscape pattern,the difference between the expected heterozygosity and observed heterozygosity is significantly reduced,and the Mantel r value is lower than that in 2018,It show that the optimized landscape pattern is conducive to the protection of population genetic diversity.(3)The remote sensing images of Zixing City in 2003 and 2018 were cropped to obtain remote sensing images of Dongjiang Lake Wetland Park,and then image preprocessing was performed to obtain the classification of landscape types of Dongjiang Lake Wetland Park.Using landcape pattern index analysis:in 2003,there were 4250 plaques in the region.the number of plaques was 4457 in 2018 the number of plaques increased by 474.Athough the overall plaque density index has decreased,the landscape pattern does not show too much fragnmentation.However,in the wetland landscape type,the number of plaques increased from 53 to 87,the proportion of plaques increased from 1.24%in 2003 to 1.84%in 2018,an increase of 0.6%,plaque density index.From 0.12 to 0.21,the wetland landscape presents a relatively obvious fragmentation trend.Through simulation studies,it shows that:under the landscape pattern of 2003,the difference between the observational heterozygosity Ho and the expected heterozygosity He about the reed is small,and the Mantel r value is between 0 and 0.1.It shows that the landscape pattern in 2003 has little effect on the genetic differentiation of Phragmites australis and rich in genetic diversity.Under the landscape pattern of 2018,the difference between Ho and He increased,the mantel r value increased linearly and was unstable,which indicated that the landscape pettern in 2018 had a significant impact on the genetic diversity of Phragmites australis and led to a decrease in genetic diversity of reeds.the landscape pettern in 2018 had a significant impact on the genetic diversity of Phragmites australis and led to a decrease in genetic diversity of reeds.