Soil Physical And Chemical Properties And Soil Bacterial Diversity In Various Forest Type Of Urban Forest

Urban forestry plays an important role in the construction of city ecological environment. Soil is the necessary fundamental substance for sustainable development and management of forest. As a result, research on soil nutrient distribution of urban forest and the soil microbial community is significant. This study will provide basic data and theoretical basis for management and improvement of urban forest environment, and it will speed up the construction process of city ecological environment.The urban forestry demonstration base of Northeast Forestry University is for sampling field. We collect eight soil samples on which grow different forest tree species as follow: F.mandshurica, J.mandshurica, P.tabulaeformis, P.amurense, L.gmelinii, Q.mongolica, B.platyphylla, P. sylvestnis var.mongolica. The effects of different forest types on the physical and chemical properties of soil are studied and analyzed, show that five soil index are the highest of J.mandshurica forests in all eight samples:5.464%of soil water content,7.273of pH value,26.47mu S/cm of conductivity, and22.713g/kg of organic carbon content,2.086g/kg of total nitrogen content. Total phosphorus content of Q.mongolica forest soil is0.8218g/kg as the highest of eight samples. Soil total potassium content of each samples are similar.By correlation analysis, soil water content is significant positive correlated to pH value, conductivity, total potassium and total nitrogen content. There is significantly positive correlation between soil pH value and conductivity, as well as between soil organic carbon content and total nitrogen content.The results of soil enzyme activity test show that the activities of soil peroxidase in different forest types are similar. The activity of polyphenol oxidase in J.mandshurica forests soil is the highest, and the lowest in P.amurense forests soil. Urease activity in J.mandshurica and F.mandshurica forests soil are much higher than the other six samples. Sucrase activity of P.amurense, J.mandshurica and F.mandshurica forests soil is higher, whereas three conifer samples are very low.The results of soil microbial community count are that the growth curve of bacteria in the soil is a logarithmic curve, and fungi show nearly S type curve. Actinomycetes display different growing curves among the samples. Growth curve of actinomycetes in B.platyphylla forest soil presents typical logarithmic curve, but some others such as P. sylvestnis var.mongolica, F.mandshurica, and J.mandshurica forest soil, whose curves are more stable, tend to be grow at a constant speed.454high-throughput sequencing is used for Metagenomics sequencing of bacterial colonies of eight samples, the result show that soil bacteria mainly include:Actinobacteria, Acidobacteria, Proteobacteria, Chloroflexi, Planctomycetes, Nitrospirae, Gemmatimonadetes, and Verrucomicrobia. These bacterial phyla above are the advantage phylum. The relative abundance of the bacteria is very significant positive/negative correlated with soil water content, soil pH value, soil conductivity and some other physical and chemical factors. The relative abundance of Proteobacteria occupies the largest proportion in all eight samples, the proportion of F.mandshurica, and J.mandshurica forests soil is the highest, reaching37.86%and37.19%respectively, which is the most advantage phylum of this two samples. While the relative abundances of the other six samples are low, they are all between20%and28%. The abundances of Actinobacteria are accounted for larger proportion in eight samples, which is up to42.7%in P.amurense sample, close to half of total bacterial numbers. And its proportion in B.platyphylla and P.amurense forests soil are40.3%and39.7%respectively. It shows a great difference for abundances of Actinobacteria among F.mandshurica, J.mandshurica forests soil and six other samples, which both are below20%, but still as the dominant phylum. This result is positive correlated with the soil water content, pH value, and soil conductivity.