Study On Soil Microbial Structure And Functional Characteristics Of Three Plantation Forests In The Semi-arid Areas Of Northwest Liaoning

The Northwestern Liaoning,which natural condition is quite harsh,has been the most serious region facing up with hazards of sandstorm in Liaoning,while artificial afforestation technique is the important measure to improve its ecosystem environment.In this study,three plantation forests,including Pinus sylvestris,Pinus tabuliformis and Populus L.were analyzed in soil microbial community structure and function.Meanwhile,soil chemical characteristics were determined to explore their correlation with metabolic activity and function of soil microbial community under different plantation forests in this area.The results showed that compared with Pinus sylvestris and Pinus tabuliformis,Populus L.can significantly increases soil dissolved organic carbon and available P,and reduce C/N.The carbon utilization capacity of soil microbial communities(AWCD)was following the order of Populus L.>Pinus sylvestris>Pinus tabuliformis.The Shannon diversity index,Simpson diversity index,and Mc Intosh diversity index of soil microbial community under the Populus × canadensis Moench were significantly higher than those of Pinus sylvestris and Pinus tabuliformis(P<0.05).Principal component analysis and heatmap plots indicated that soil microbial communities were divided into two different functional groups,especially between coniferous forests and broadleaf forest,and principal different carbon sources include Pyruvic acid methyl ester,i-erythritol,and 2-hydroxybenzoic acid.There were 9 dominant phyla of soil bacterial community,and Proteobacteria is the most dominant group under different plantations.The relative abundance of Proteobacteria in the soil of Populus L.was significantly higher than that of others(P<0.05).The relative abundance of Chloroflexi under Pinus tabuliformis was significantly lower than others(P<0.05).There were 5 dominant phyla of soil fungi community,and Ascomycota is the most dominant group under different plantations.The relative abundance of Olpidiomycota under Pinus sylvestris was significantly higher than that in Populus L.(P<0.05).The ACE index and Chao1 index of soil bacterial community in different plantations was following the order of Pinus sylvestris>Pinus tabuliformis>Populus L..The Shannon index and Simpson index of Populus L.were higher.The trends of Shannon index,Simpson index,ACE index and Chao 1index of soil fungal community under different plantation forests were the same,they were Populus L.>Pinus sylvestris>Pinus tabuliformis.At the same time,the results of heatmap analysis and NMDS analysis of fungal community composition in different plantation forests were similar to that of bacteria,that is,the composition of soil fungal community in coniferous forest and broad-leaved forest was quite different.In conclusion,the metabolic activities,composition and functional diversity of soil microbial community in Populus L.plantations were better than those in Pinus tabulaeformis and Pinus sylvestris plantations in this area.