Response Of Soil Microbial Community To Simulated Warming And Precipitation In River Source Wetland Of Qinghai Lake

Wetlands have the functions of water conservation,climate regulation and environmental improvement.As an important biological factor in the terrestrial ecosystem,soil microorganisms play an important role in regulating the soil nutrient cycle,organic matter decomposition and other soil ecosystem functions.This study takes the River Source Wetland soil of Qinghai Lake basin as the research object.Through the open-top chamber(OTC)and the simulated precipitation change device(increase precipitation by 25%,75%,and decrease precipitation by 25% and 75%),the macro-genome sequencing technology and the physical and chemical properties of the soil,the impact mechanism of warming and precipitation change on the soil microbial community of the source wetland of Qinghai Lake is discussed.The main research results are as follows:(1)The change of temperature and precipitation did not significantly affect the horizontal dominant flora of soil microbiota.The higher relative abundance of bacteria in this area were Proteobacteria,Actinomycetes,Fumonites,Bacteroides and Thick-walled bacteria,and the highest relative abundance of fungi was Ascomycetes.However,there were differences in the types of different microorganisms under the conditions of temperature and precipitation change,among which the precipitation change treatment belonged to the horizontal differential microorganisms,most of which belonged to Proteobacteria.(2)Soil microbial community in the River Source Wetland of Qinghai Lake αThe response of diversity to warming was obvious.The warming treatment increased the soil microbial richness of the same soil layer as the natural control,and the warming treatment of 10～20cm soil layer was significantly higher than the natural control(P< 0.05).The warming treatment reduced the species evenness of the same soil layer as the natural control.The diversity showed that the warming treatment of0～10cm soil layer was lower than the natural control,and the warming treatment of10～20cm soil layer was higher than the natural control.Under the condition of precipitation change,the richness index of the same soil layer showed that the natural control was higher than the precipitation change treatment;The species evenness index and diversity index of 0～10cm soil layer were the highest in-25% treatment,and the highest in+75% treatment of 10～20cm soil layer,but the Simpson index was the highest in-25% treatment of 10～20cm soil layer.(3)The soil p H of 0～10cm and 10～20cm was significantly increased by warming treatment(P< 0.05).The soil temperature,total nitrogen and total carbon showed a trend of 0～10cm>10～20cm under warming treatment.There were significant differences in soil moisture between different soil layers under the same treatment condition(P< 0.05)among the four precipitation treatments.Compared with the natural control,the soil moisture of 10～20 cm soil layer was significantly increased by+25% and+75% treatments(P< 0.05).Total carbon,total nitrogen,soil temperature and soil humidity all showed a trend of 0～10cm>10～20cm under the condition of precipitation change.(4)The warming treatment significantly improved the pathway of benzoic acid degradation and geraniol degradation,and significantly reduced the histidine metabolism and nucleotide-excision repair pathway.Under the condition of precipitation change,-75% treatment significantly improved bacterial chemotaxis,flagella components,MAPK signal pathway-yeast pathway,-25% treatment significantly improved non-homologous terminal pathway,+25% treatment significantly improved sphingolipids metabolism,AMPK signal pathway,steroid hormone biosynthesis pathway,and the above three precipitation treatments significantly reduced arginine and proline metabolism,bacterial invasion of epithelial cells and other pathways.The changes of temperature and precipitation did not significantly affect the abundance of carbon and nitrogen metabolism genes.(5)Under the condition of warming treatment,soil moisture,temperature and p H are the main factors affecting soil microbial community;Under the condition of precipitation change,soil temperature,total carbon and total nitrogen are the main factors affecting soil microbial community.In conclusion,this study explored the response mechanism of soil microbial community in the River Source Wetland of Qinghai Lake Basin on the Qinghai-Tibet Plateau under the conditions of simulated warming and precipitation changes.It was found that warming treatment and precipitation change had no significant effect on soil microbial dominant flora,which were all Proteobacteria.However,α diversity index and metabolic pathway were different in response to temperature increase and precipitation change.This study revealed the response characteristics of soil microbial community to temperature increase and precipitation change in the River Source Wetland of Qinghai Lake.The relevant research results can provide a scientific basis for understanding the effects of climate change on soil microbial community structure and metabolic pathway in the River Source wetland of Qinghai Lake ecosystem.