The Impact Of Removing Dasiphora Fruticosa And Simulating Warming On The Richness And Community Composition Of Soil Microorganism And Nematode In Alpine Meadow

Underground biomes play an important role in maintaining the function and stability of the ecosystem.Soil microorganisms and nematodes are important components of underground biome,and their richness and composition are affected by aboveground vegetation and climate warming.Due to climate change and human activities,shrub expansion is becoming more and more serious in the Qinghai-Tibet Plateau.At present,there are many studies on the patterns of aboveground and underground biome changes mediated by dominant shrubs or climate warming,However,few researches have combined the two factors to study the interaction mechanism of the two on the underground biome.In this study,Dasiphora fruticosa,a dominant shrub on the Qinghai-Tibet Plateau,was selected as the experimental material to study the effects and mechanisms of Dasiphora fruticosa and warming with their interaction on the richness and composition of soil microbial and nematode communities.In this study,soil microorganisms and nematodes were used as the research object,located on the eastern foothills of the Qinghai-Tibet Plateau in the alpine meadow area.The presence or absence of the dominant shrub Dasiphora fruticosa was controlled by removing experiment,and open-top chambers(OTCs)were used to control warming or not.Got four treatments: Without shrub Control(RN);With shrub Control(PN);Without shrub Warming(RW);With shrub Warming(PW).Through investigation of aboveground vegetation,determination of soil physiochemistry,high-throughput sequencing of microorganisms,identification of nematode communities and calculation of nematode functional indexes,to exploring the effects of Dasiphora fruticosa and warming with their interaction on these indexes.Through the construction of structural equation model,to explore the direct or indirect ways of the effects of Dasiphora fruticosa and warming on the richness of underground microbial community and nematode community through soil physiochemistry and aboveground vegetation richness.The results show that:1)The application of OTCs did increase the soil temperature,the soil temperature rose by 1.48? with shrub,and rose by 0.8? without shrub.The interaction between Dasiphora fruticosa and warming significantly affected soil organic carbon.Warming could reverse the negative effect of Dasiphora fruticosa on soil organic carbon.The soil total nitrogen content was significantly reduced by warming when Dasiphora fruticosa was removed.There was no significant effect on other physical and chemical indexes.The increase of soil organic carbon and total nitrogen under canopy by warming may due to the acceleration of soil nutrient cycling and decomposition of litter,which provides a good nutrient source for soil.2)Warming significantly increased soil fungi richness and increase about 12%,while Dasiphora fruticosa and warming with their interaction had no significant effect on soil bacterial richness.The community composition at the level of bacteria phylum was significantly changed by removing Dasiphora fruticosa,but not in fungi phylum.There were 16 indicator species OTU in the warming treatment of fungi,and the OTU with clear classification belonged to Ascomycota and Basidiomycota.There were 72 indicator species of OTUs in shrub treatment of bacteria,more than half of which belonged to Proteobacteria.The soil microbial community richness was not directly affected by Dasiphora fruticosa and Warming but warming could indirectly improve soil microbial community richness under Dasiphora fruticosa by affecting soil physiochemistry.3)The interaction between Dasiphora fruticosa and warming significantly affected the richness of soil nematode community.Dasiphora fruticosa had no significant effect on soil nematode community richness in the nature condition,but significantly increased soil nematode community richness after warming.The community composition of soil nematode was significantly changed by removing Dasiphora fruticosa.Omnivorous and predatory nematodes: Eudorylaimus and Epidorylaimus are the indicator species under RN,PN and PW treatments.Under the warming treatment,nematode richness was directly positively affected by Dasiphora fruticosa,while the soil nematode richness was not indirectly affected by soil physiochemistry?plant and soil microbial richness.The results of this study indicated that the soil microbial and nematode richness of Dasiphora fruticose was improved by applying warming treatment,soil microbial richness was indirectly regulated by the chemical properties,while soil nematodes richness was directly regulated by Dasiphora fruticosa and warming.The community composition of soil bacteria and nematodes was significantly changed by removing Dasiphora fruticosa.Our research is intended to reveal the dominant shrubs of Alpine Meadow on the Qinghai-Tibet Plateau,Dasiphora fruticosa and warming,as well as the ways and mechanisms of their interaction on the richness and composition of soil microbes and nematode communities,and help us to deeply understand the action mode and mechanism of the dominant above-ground plants and climate change on the underground biome,to providing theoretical basis for maintaining the stability of alpine meadow ecosystem.