Seasonal Dynamics Of Soil Microbial Community Structure And Functional Diversity Of Plants In Extreme Arid Desert

Land desertification is a major ecological security issue affecting human survival and development,and desertification prevention and control is also an important part of our ecological civilization construction.Desert itself is relatively fragile to environmental changes.At the same time,most studies on the structure of soil microbial communities focus on spatial scales,while there are fewer studies on time spans,especially those involving seasonal changes in the structure and function of desert soil microbial communities.In desert areas,the soil is poor,and plants will form a "resource island" effect.Nutrients are more concentrated around plants,and the corresponding microorganisms grow and multiply in the rhizosphere of plants.And the change of seasons will cause the change of the surrounding environment conditions and then cause the difference of the microbial community.Studying the soil microbial community structure of different plants and seasons in extremely arid desert areas is beneficial to the restoration of vegetation in desert areas.In this paper,the Rhizosphere soils of five typical vegetation types,including Sympegma regelii,Nitraria sphaerocarpa,Salsola passerine,Reaumuria soongorica and Ephedra przewalskii,were taken as the research objects in summer,autumn and winter of 2019 and autumn and winter of 2020 in Anxi National Nature Reserve.Phospholipid fatty acid(PLFA)and Biolog ECO ecological plate method were used to explore the structure and functional metabolism of soil microbial community,and the relationship between them and soil physical and chemical properties was studied,so as to provide a basis for the prevention of land desertification and the restoration of desert vegetation.The main results are as follows:1.There were significant differences in the soil physical and chemical properties of extremely dry deserts between different plants and seasons,and there were significant interactions.Compared with vegetation changes,seasonal changes explained more differences in soil factors in 2019.Compared with summer and winter after snow,its soil physical and chemical properties were significantly lower in autumn.2.The soil microbial community structure in the extreme arid desert had significant differences between plants and seasons,and there were significant interactions.There were significant differences between vegetation types in 2020,and there were significant interactions.Its content was Gram-negative bacteria > Gram-positive bacteria >Actinomycetes > Fungi > AM fungi.In the summer and winter of 2019,the microbial content in S.regelii was significantly higher than that of the other four plants,while the lowest value of microbial PLFA was detected in E.przewalskii,and the difference in fungi/bacteria between autumn and summer plants was significant.3.The biomass of soil microorganisms included total PLFA,Gram-positive bacteria,Gram-negative,fungi,arbuscular mycorrhizal fungi and actinomycetes was significantly positively correlated with soil factors such as available phosphorus,PH and soil moisture,the ratio of fungi to bacteria was negatively correlated with soil organic carbon and soil moisture in 2019.4.There were significant differences in the utilization of six types of carbon sources by microorganisms in the 2019 and 2020 season.The utilization of some carbon sources was significantly different among plants.In terms of differences in the use of carbon sources,compared with vegetation,the six types of carbon sources were obviously more affected by the seasons.5.The six types of carbon sources were significantly positively correlated with nitrate nitrogen,PH,ammonia nitrogen,humidity,and available phosphorus.Gram-negative bacteria,fungi,AM fungi,actinomycetes,total PLFA,and the utilization rates of the six types of carbon sources were all positively correlated.Gram-positive bacteria were significantly positively correlated with polymers,amines,phenolic acids,and amino acids.Fungi/bacteria was significantly positively correlated with carbohydrates,carboxylic acids,amines,and phenolic acids.6.There were significant differences in carbon source metabolic diversity among soil microbial communities in two years different seasons,and the diversity index in autumn was significantly lower than that in summer and winter after snowmelt,but the difference among plants was not significant,and seasons accounted for most of the differences in carbon metabolism.