Bacterial Community Characteristics Of Different Forest Types

The geographical conditions of the cites are complex,the environmental conditions are variable,and the airborne microorganisms are greatly influenced by human activities.Therefore,the air microbial community structure and diversity characteristics are significantly different in different parts of the city.However,he air microbial communities are different in forest ecosystems and cities,the factors that affect the structure and diversity of air microbial communities may be more complex.In recent years,studies on forest air fungi have provided us with a good understanding of the community structure and diversity of air fungi in different forest environments,as well as the major affecting factors about the fungus concentration,community structure,and diversity of airborne fungi.However,little research about air bacterial communities in the forest environment has been conducted.It is necessary to study the community structure and diversity of air bacteria in the forest,and the environmental factors related to the forest air bacteria community.In this study,Fifty-four air bacterial samples were collected by impact sampling from the Cunninghamia Lanceolata(CL),coniferous and broad-leaved mixed forest(MF),broad-leaved forest(BF),litchi forest(LC),bamboo forest(PH),and inter-forest road(CK)for impact sampling,and they were subjected to 16 S rDNA high-throughput sequencing.As the same time,Environmental factors such as microclimate,canopy structure,and soil physical and chemical properties were collected.By analyzing the structural and diversity characteristics of air bacterial communities and the main influencing factors affecting air bacterial communities in different types of forest lands and forest roads,to promote our understanding of airborne bacterial communities in forest ecosystems.Main research results include:(1)Vegetation-covered forest areas have more specific types of air bacteria.In the five forest types(CL,MF,BF,LC,PH),the total number of OTUs obtained by classification decreased in turn.The number of OTU were 816,689,635,583,557 respectively,which was all larger than CK(520).The more types of airborne bacteria,the more typical airborne bacteria are found between plots and plots.The number of OTUs common to the three duplicate plots of CL,MF,BF,LC,PH,and CK are 247,236,239,250,255,244,respectively.The percentage of the total number of OTUs in the forest is increased in turn,which is inversely proportional to the total number of OTUs.(2)At the phylum and genus level,the dominant bacterial communities with abundance greater than 1% on different forest types and forest roads are the same,and their abundances are highly similar.Although the dominant bacterial community have low abundance,they are rich in species.At the phylum level,the dominant bacterial communities in the five forest types and forest roads were Proteobacteria and Firmicutes,accounting for 53.76% and 45.97% of the total.At the genus level,the dominant bacterial communities were Citrobacter,Acinetobacter,Pseudomonas,Bacillu,Enterococcus and Streptococcus,accounting for 55.53% of the total.The abundance of each phylum and major genus in CL and MF were higher than other forest types.And the two forest types with similar vegetation composition have more similar air bacterial community structure.The community structure of PH,LC,and CK were similar at the gate level,and the community structure of LC and BF;PH and CK were similar at the genus level.(3)Different woodland types and forest roads did not have significant effects on the bacterial richness and diversity of air,but they had significant effects on the phylogenetic diversity.The richness and evenness of air bacterial communities were higher in CL and lower in LC.There was little difference in air bacterial community diversity between CL and MF,CL and BF,and CK,PH and LC,while the diversity of bacterial communities in MF and CK and LC air was quite different.(4)Compared with the microclimate environment and canopy structure,soil physicochemical properties and enzyme content had a greater correlation with the air bacterial communities.The bacterial communities Citrobacter,Pseudomonas,Acinetobacter,Enterococcus,Streptococcus,and Leuconostoc are significantly associated with environmental factors.The genus of Leuconostoc was more related to the structure of the forest canopy,while the community structure and diversity characteristics of other genus was more related to the soil physicochemical properties(such as soil pH,Olsen-K,Olsen-P,acid phosphatase,soil urease,and soil temperature).Soil PH,Olsen-K,Olsen-P,and soil urease contents were clustered into one category,and acid phosphatase content and soil temperature were clustered into one another.The environmental effects of the two categories on the air bacterial community structure were opposite.