After Nitrogen Addition Northwest Liaoning Steppe Woodland Structure Of Soil Bacteria And Its Relationship With Soil Carbon And Nitrogen

In order to understand the effects of atmospheric nitrogen deposition on soil bacterial communities in sparse forest grassland ecosystem.In this study,the structure of soil bacteria community and the change of soil carbon and nitrogen were analyzed by means of artificial simulation of nitrogen deposition(0?10?25?40 and 80kgN ·hm-2 ·a-1)and high throughput analysis in the shrub grassland located in the northwest of Liaoning province.In this experiment,NO(blank control group),N10,N25,N40 and N80 were added into five gradients,and the 16S of rDNA in the treated soil was sequenced for three generations.1.The results showed that the abundance of bacteria would change with the amount of nitrogen.The abundance of bacterial community varied with the amount of nitrogen added.In the control soil,Firmicutes was dominant,its abundance was 37%,Proteobacteria and Bacteroidetes were 24.7%and 18.1%,and the abundance of Actinobacteria and Acidobacteria was 6.75%and 6.34%.With the increase of nitrogen,the advantage of Firmicutes,Proteobacteria,Bacteroidetes and the second dominant phylum were significantly decreased,while Actinobacteria,Acidobacteria and Chloroflexi had the advantage of increased,especially the dominance of Acidobacteria increased obviously.The results showed that the control soil,detected 172 bacterial genera,the dominant genus of Veillonella,its abundance was 18.9%,Escherichia,Clostridium and Bacteroides abundance at 4.2%-5.3%,followed by the dominant genera.Candidatus,Escherichia and Solibacter Clostridium became dominant genera in the N10 gradient,and their abundance was in 2.0%-3.3%.Under the N25 level,the dominant species was Aquabacterium,its abundance was 7.5%,Sphingomonas and Kaistobacter abundance in 2.3%-2.7%.Under the N40 gradient,Escherichia,Clostridium,Solibacte Candidatus and Sphingomonas were the dominant genera,and the abundance was in 1.2%-3.3%.In the N80 level,Sphingomonas,Kaistobacter,Solibacter Candidatus,Escherichia and Rhodoplanes abundance in the 1.3%-2.6%,there was no obvious advantage of bacteria.In summary,the change of soil bacterial structure after nitrogen addition,the Veillonella in the control soil was dominant,and the bacteria were detected.With the increase of nitrogen content,the dominance of Veillonella,Escherichia,Clostridium and Bacteroides decreased or disappeared,while the proportion of unknown bacteria increased significantly,and the dominant species changed from single to multiple.Bacterial phylumhad also changed with the amount of nitrogen added.In the control soil,Firmicutes was dominant,its abundance was 37%,Proteobacteria and Bacteroidetes were 24.7%and 18.1%,and the abundance of Actinobacteria and Acidobacteria was 6.75%and 6.34%.With the increase of nitrogen,the advantage of Firmicutes,Proteobacteria,Bacteroidetes and the second dominant phylum were significantly decreased,while Actinobacteria,Acidobacteria and Chloroflexi had the advantage of increased,especially the dominance of Acidobacteria increased obviously.2.Through the sequencing of soil microbial 16S rDNA high-throughput analysis,diversity index of Al rural forest steppe zone wheatgrass community soil bacteria In this experiment,the Chaol index of five gradients is N10>N80>N40>N25>NO.The ACE index is N80>N10>N40>N25>NO.The Simpson index is N10>N25>N40>N80>N0.The Shannon index is N10>N25>N80>N40>NO.Nitrogen treatment not only affected the composition and abundance of soil bacterial community,but also affected the abundance of functional groups.From the results of this experiment,we can conclude that nitrogen addition can help increase the abundance of most functional groups.Only two functional groups,namely nucleotide metabolism and cofactor and vitamin metabolism,are inhibited.3.Five gradients soil chemical properties were measured:The results showed that the contents of pH,ammonia nitrogen and nitrate nitrogen in soil were significantly different between the 5 gradients.The results showed that the contents of pH,ammonia nitrogen and nitrate nitrogen in soil were significantly different between the 5 gradients.The pH value of soil in this experiment was between 5.43-5.95,which was acidic.With the increase of nitrogen concentration,soil pH showed a decreasing trend.The content of NH4+-N in soil was 0.066 mg·kg-1-0.165 mg · kg-1,and its content was the lowest in NO nitrogen treatment plots,the highest in N80 treatment,and the difference was significant between the two groups.The content of nitrate in soil was in the range of 0.341 mg·kg-1-0.636mg· kg-1,the content of N80 soil samples was significantly higher than that of other concentrations.The total nitrogen content in the five groups was between 1.296g· kg-1-1.768 g·kg-1,no significant difference.The soil organic matter content of five gradients ranged from 3.699 g/kg-5.057g/kg,and there was no significant difference.There was no significant difference in carbon to nitrogen ratio(5.604-5.496).Therefore,the content of soil pH,ammonia nitrogen and nitrate nitrogen three indicators affect the structure of soil nutrients,which may be the factors affecting soil microbial community structure and abundance.4.From the distance map and community cluster analysis of the matrix composition of thermography can be seen that the bacterial abundance in the control group,there is a big difference with the increase of nitrogen treatment,and the advantage of category and genus of the bacterial community structure has undergone great changes,these changes can guess is caused by nitrogen.