The Repsonses And Mechanisms Of Mebabolic Activity Of Soil Microorganisms With Halophysic Succession In The Yellow River Delta

There were complete succession sequences of "bare land-light plate-strong salt tolerant vegetation-mild salt tolerant vegetation" in the the Yellow River Delta.It was a natural laboratory to study the relationship between soil microbial catabolic diversity and the succession of salt vegetation.Currently,study of the diversity of soil microbial structure in the the Yellow River Delta were relatively more,while the relationship between the metabolic activity of soil microorganisms with halophytic succession and the relationship between metabolic activity and genetic diversity were relatively less.Biolog micro-plate technique(Biolog-Eco micro-plate and Biolog-FF micro-plate technique)and metagenomics technology(16SrDNA-PCR amplification technology and high-throughput sequencing technology)werer adopted and soil microbial metabolic activities with succession of halophytic vegetations were research,meanwhile,the mechanism of the soil microbial metabolic activity with salt vegetation succession were discussed.Otherwise,correlations of soil microbial metabolic diversity and genetic diversity were studied preliminarily.Catabolic avtivities of soil microorganisms with succession of halophytic vegetation were studied by the establishment of community level physiological profiles(CLPPs).CLPPs include:Average well color development;4 kinds of functional diversity index(Shannon-Wiener index,richness indexes,dominance(Simpson index),evenness index(Pielou evenness index);Principal component analysis;meanwhile,the different soil layers are divided into A layer and B layer in this study.This study will help to solve the changes in the metabolic diversity of soil microorganisms with the succession of halophytic vegetation,which foud out the environmental factors that affected the metabolic activity of soil micoorganisms,and further revealed the relationship between microbial genetic diversity and carbon source metabolism,and the conservation and recovery of the ecosystem in the Yellow River,which rovide important theoretical basis.A layer(0-20 cm)is the root layer,and the B layer(20-40cm)is a non-root layer.The results of the study show that:(1)With the succession of halophytic vegetation included “bare board-severe salt tolerant communities(Saline Seepweed,Angiospermae)-mild salt communities(Imperata and A.Venetum.),catabolic avtivities of soil microorganisms were improved,meanwhile,the metabolic diversity was increased significantly,and the index of functional diversity was continuously improved.soil environments of microorganisms were optimized.There were significant correlations between metabolic diversity and genetic diversity,with the succession of halophytic vegetation.(2)With the process of " bare land-severe salt tolerant communities(Saline Seepweed,Angiospermae)-mild salt communities(Imperata and A.Venetum.)",soil fertility(soil active organic matter,total nitrogen,alkali hydrolyzed nitrogen and so on)were increased continuously,while soil conductivity was dreased.With the succession of halophytic vegetation,soil qualies were improved.With the succession of halophytic vegetation,AWCD value,Shannon-Wiener index,richness,dominance and evenness index of soil bacteria in the A layer increased significantly(P<0.05).The types of metabolism of soil microorganisms were continuously enriched.Metabolic acitivies of soil bacteria in B layer showed an increasing trend in general,while fungal metabolic activity covered by Angiospermae was that of A.Venetum.Electrical conductivity,total nitrogen,alkali hydrolysable nitrogen and active organic matter are main factors that controlled catabolic activities of soil microbial communities.Total nitrogen,alkali hydrolysable nitrogen and active organic matter significantly promoted metabolic activity of soil bacterial;while soil salinity has a significant inhibitory effect on the growth of soil bacteria(P<0.01).(3)The metabolic activity of soil fungi also increased significantly with the succession of salt vegetation.The AWCDs of soil fungi covered by Imperata community were stronger than others.Meanwhile,AWCDs of soil fungi were weakest in bare land.In 20-40 cm soil layer,AWCDs of soil fungi covered by Angiospermae community were stronger than that of A.Venetum community,which disrupted that sort.Metabolic diversity indexes of soil fungi were significant increased with succession of halophytic vegetation in 0-20 cm soil layer,the 4 types of diversity index were increased significantly.Meanwhile,in 20-40 cm soil layer,metabolic diversity indexes of soil fungi covered by Imperata community were higher than others,while there was non-significant difference between bare land and A.Venetum.Soil physical and chemical properties have different effects on metabolic activity of soil fungi.EC,urease,catalase,alkali-hydrolysable nitrogen and soil active organic matter are main factors that controlled metabolism of soil fungal.Microbial genetic diversity and functional diversity of RDA analysis showed that:(1)The microbial phylum of were constantly enriched and the relative abundance was increased with the succession of halophytic vegetation,while the relative abundance of unclassified fungi decreased continuously.(2)In the soil of A layer,organic acids and carbohydrates metabolized by Acidobacteria were stronger,and the metabolic activities of the polymer were stronger for Firmicutes,and the metabolic activities of the Bacillus nitrificans and Verrucomicrobia is stronger on the polyol,but the relationship between the metabolic activity of the soil bacteria in B layer(non-root layer)and the genetic diversity is not significant.(3)In the soil of A layer,there was a significant positive correlation between the metabolic diversity of soil fungi and the relative abundance of Basidiomycetes and the Chytridiomycota,but there was a significant positive correlation between the metabolic diversity of fungi and the relative abundance of the Angiomycetes and Glomeromycota in the B layer soil.