Study Of Soil Physicochemical Properties And Bacterial Community Structure Of Urban Green Spaces In Beijing

As an important part of urban ecosystem,urban green space plays an important role in urban public health and landscape ecology.Bacteria are the most abundant and widely distributed microbial group in soil,which not only drives the biogeochemical cycle,but also plays an important role in the soil ecosystem of urban green space.This study analyzed the soil physical and chemical properties under different green space types and park ages and the composition,structure and diversity of bacterial communities in the inner city inside Beijing's 5th-ring,and analyzed the changes in the spatial and temporal characteristics of soil physical and chemical properties caused by different green land types and park ages.The influence of the community,and then the corresponding characteristics and laws of the soil bacterial community on the management of green space,the results of this study will help reveal the main problems of the green space soils in the urban area of Beijing,and comprehensively evaluate the soil quality.Including providing scientific basis,it also has important guiding significance for Beijing urban green space management plan.The main research results were as follows:(1)Green space types significantly affects the physical and chemical properties of the soil.The bulk density of different types of green spaces was 1.08?2.06 g/cm3,with an average of 1.60 g/cm3.Street green space shows a significantly higher content of bulk density than other three green space types.The soil pH values of different types of green spaces ranged from 6.92 to 8.49,and the soils of all the samples were alkaline.The pH of the street green space was significantly higher than that of the other three types of green spaces.The average contents of soil organic matter and total nitrogen in different types of green spaces were 17.61g/kg and 0.74g/kg,respectively.Among the four green space types,the organic matter and total nitrogen content of park green space were the highest.The average content of available nutrients were significantly higher in the park green spaces than other three green spaces.(2)Green space types significantly affects the composition,structure and diversity of soil bacterial communities.The soil bacterial diversity of different types of green spaces presents "park green space>attach green space>residential green space>street green space",and the soil bacterial richness of the different green spaces presents "attach green space>park green space>residential green space>street green space." There are some differences in the composition and structure of bacterial community in different types of green spaces at the level of phylum,class and genus.The main groups of soil bacterial phylum levels are Acidobacteria,Proteobacteria,Chloroflexi,Actinobacteria and Gemmatimonadetes,and there are significant differences in the relative abundance of various groups at the phylum level.Each subfamily in the genus is mainly composed,and there are also differences in various groups of bacteriological levels.The dominant genus of different green types includes RB41,Nitrospira,Sphingomonas and H16.There is also a significant difference in the relative abundance of the various groups,and a large number of unclassified bacterial communities are also detected.The main factors controlling the bacterial diversity and bacterial community structure of different types of green space soils were soil organic matter,total nitrogen,bulk density and pH.(3)Park age significantly affects the physical and chemical properties of soil.The soil bulk density of the old parks is 1.41?1.67 g/cm3,with an average of 1.56 g/cm3.The soil bulk density of the young parks is 1.44?1.69 g/cm3,and the average content is 1.62 g/cm3.The pH value of the old parks is between 6.49 and 7.20,and the pH value of the young parks is between 6.94 and 7.44.The average content of soil organic matter and total nitrogen in the old parks was 36.45g/kg and 1.43g/kg,respectively.The average content of soil organic matter and total nitrogen in the young parks was 23.22g/kg and 1.05g/kg.The average content of available nutrients in the old parks were significantly higher than in the young parks.(4)Park age significantly affected the composition,structure and diversity of soil bacterial communities.There are significant differences in soil bacterial diversity under different park ages,mainly because the diversity and richness of bacterial community in the old parks are significantly higher than those in the young parks.There are some differences in the composition and structure of bacterial community under different green space types.The main dominant groups of soil bacteria in the old parks and the young parks are Acidobacteria,Proteobacteria,Chloroflexi and Actinobacteria,and their relative abundances are significantly different between the old parks and the young parks.The main abundances of the class level Acidobacteria,Actinobacteria and Proteobacteria are mainly different under different park ages.The dominant genus of the young parks and the old parks includes RB41,Nitrospira,H16 and Sphingomonas.The main factors controlling soil bacterial diversity under different park ages were soil organic matter,total nitrogen and water content;the main factors controlling soil bacterial community structure under different park ages were soil organic matter and total nitrogen.