The Characteristics Of Soil Microbial Structure And Diversity On Nitraria Tangutorum Nebkhas Of Different Development Stages In Desert Steppe

Shrub hebkhas can prevent soil erosion and nutrient loss,provide higher soil nutrients,and affect the biogeochemical cycling process of ecosystems.However,ecological function of soil microbial diversity during the process of shrub development is less studied,so that knowledge of the biochemistry process of formation of the shrub fertile island still lack,it is difficult to explain phytogenic nebkha evolution mechanism and its influencing factors.In order to explore the development of soil microbial community structure and spatial distribution pattern on phytogenic nebkha of Nirtaria,This study analyzed various physical and chemical factors in soil bacterial and fungal communities,and their structure and diversity,in different evolution stages of the shrub hebkhas of Nirtaria.Various soil factors for bacteria and fungi were examined through Spearman correlation analysis.The influences of community structure and community diversity provided a basis for the stability of soil salinization ecosystem in desert steppes,and provide a reference for comprehensive understanding of the interacting mechanisms between soil nutrient transformation and microorganisms.The results showed that:1.The number of vegetation species in the mature stage of shrub hebkhas increased significantly,and the species composition changed significantly.There are significant differences in soil particle composition and nutrient content between the shrub hebkhas in different evolution stages.The main granules of the shrub hebkhas are composed of clay and silt;the shrub hebkhas of Nirtaria can increase the water content and conductivity of the soil and reduce the pH value of the soil as the evolutionary stage progresses.In the primary stage,the water content and conductivity of the middlepart of the shrub can be significantly improved,and the soil pH value can be lowered.The water storage capacity of the lower edge of the shrub is stronger at 20-40 cm.The soil nutrient contents of shrubs in different evolution stages have certain differences.With the evolution of the shrub hebkhas,the total nitrogen and organic carbon content in the soil can be increased,and the available phosphorus content is significantly improved in the topsoil of the shrub.2.Soil bacteria are at the phylum level with the small distinction among species amid different stages of evolution even if they vary in abundance exclusively.Among them,actinomycetes and proteobacteria are dominant bacteria,and both acidophilus and Bacteroides are characterized by higher abundance in the developmental stage than other evolutionary stages.There is a big difference in the abundance ratio between the order and the genus level.Both in the stages of primary,maturity and decline the 0-5cm and 10-20cm soil layers at the top of the shrub show a high degree of Rhizobium.The abundance of Clostridium was higher in developmental stage.The amount of Rhodococcus in the developmental stage of the 10-20 cm deep soil layer at the lower edge of the shrub was significantly higher than other evolutionary stages.3.The soil bacteria's observed species index in the middle of the shrub is higher than the top and bottom margins,and the bacterial abundance of the 5-10 cm deep soil layer is characterized by decline stage>maturation stage>primary stage>developmental stage;the diversity index of the community has a significant difference in the surface soil of the bottom shrub hebkhas,and its maturity stage is significantly higher than other evolution stages;the Chaol index and the ACE index increase with the evolution stage.The highest PD whole tree index is in the 0-5cm deep soil layer at the top of the shrub in the primary stage,and the difference in the preservation of the evolutionary species is the largest;the lowest PD whole tree index is in the 10-20cm deep soil layer at the lower edge of the sediment in the recession stage,which laver has the smallest difference in the preservation of evolutionary species.The soil bacterial community in the primary and developmental stages is more similar to the inter-pile ground.4.The shrubs at different evolution stages effect composition ratio and diversity of the fungal community.At the species level,the number of fungal species is mature stage>recession stage>development stage>primary stage.The dominant bacteria in the Ascomycota shrub heap,like the other bacteria,have different abundances in different evolution stages,and their abundances are mature stage>developmental stage>inter-pile ground>degraded stage>primary stage.The abundance of Basidiomycota in the recession stage was significantly lower than that in other evolution stages,and the abundance of the spores and bulbs was significantly higher than that of other stages-consistent with the change of the inter-substrate.The fungal community in the primary stage differs most from the developmental and maturity stage,while the fungal communities in the inter-substrate and declining stages are more similar.5.The observed species index of soil fungi showed an "N" type change trend with the evolution stages.The maximum value was 5-10 cm in the middle of the sand stage in the mature stage,and the minimum value was]0-20 cm in the top of the sand stage in the mature stage.The Shannon index and the Simpson index were significantly higher than the primary stage in the development and maturity stages,while the other spatial sequence positions of the shrub were not significantly different between different evolution stages;in the ACE index and the Chaol index,the abundance in recession stage is the highest;the PD whole tree index is the highest in the surface soil of the lower margin of the sand in the recession stage,and the difference in the preservation of the evolutionary species is the largest;the surface at the middle part of the shrub in the mature stage is the lowest of the PD whole tree index,and the difference in the preservation of the evolutionary species is the smallest.6.The correlation analysis between soil factors and soil microbial community structure indicated that the community composition of soil microbes was affected by various soil environmental factors,and the factors that had a greater impact on the microbial community composition of soil bacterial Communities were soil pH,clay and total nitrogen.The content of soil environmental factors had a great influence on the fungal community of the spores.The soil nutrient and soil particle composition had significant correlation with the fungal genera,and the clay content had a great influence on the fungal community composition of the shrub soil.