The Regulation Of The Composition Of Three Shrub Species And Arbuscular Mycorrhizal Fungi On Soil Microhabitat In Daqingshan Mountain

The Daqingshan mountain in Inner Mongolia Autonomous Region are important ecological barrier for the region of Hohhot,Baotou,Beijing and Tianjin.Clematis fruticosa,Prunus mongolica and Spiraea pubescens are 3 typical native shrub species,which can form a well symbiotic relationship with arbuscular mycorrhizal fungi(AMF)in Daqingshan mountain.They can adapt well to the environment of arid sunny or semi-sunny slopes,and have a higher natural vegetation restoration potential.In order to explore the regulatory mechanism of shrub species composition and AMF to the stability of soil micro-ecological environment,the microhabitat in the rhizosphere soil of 3 native shrubs was investigated.The pure and mixed stands of C.fruticosa,P.mongolica and S.pubescens were selected,and the planting patterns(the treatments including monoculture and different mixed planting orders)and AMF inoculation(including inoculated with AMF and inoculated without AMF treatments)verification experiments were set.The rhizosphere soil of shrubs was collected.The soil chemical properties,soil microbial biomass and soil enzyme activities were determined,and the AMF community structure was estimated by Illumina Miseq sequencing technology.In order to explore the driving factors of soil AMF community structure and ecoenzymatic stoichiometry,the variations of micro-ecological environment in rhizosphere soil of different treatments were analyzed.The optimal planting pattern of native shrubs was selected combining with the changing rule of the seedling growth and micro-ecological environment in rhizosphere soil.This will provide a theoretical basis for the vegetation restoration in arid mountainous areas of western China.The main results were as followed:(1)The ratios of soil microbial biomass stoichiometries and ecoenzymatic stoichiometries related to phosphorus(P)were the lowest,and the soil microbial P limitation was the highest in S.pubescens pure stand.The ratios of soil microbial biomass stoichiometries and ecoenzymatic stoichiometries related to carbon(C)and P were lower,and the soil microbial C and P limitations were lower in C.fruticosa and S.pubescens mixed stand.(2)The AMF richness and diversity indexes were the highest and lowest in P.mongolica and S.pubescens pure stands,respectively.Compared with S.pubescens pure stand,the AMF richness of C.fruticosa and S.pubescens mixed stand was significantly increased.The spore density of the mixed stands was significantly higher than that of the pure stands.The dominant genus of AMF community in different shrub stands was Glomus.Compared with the pure shrub stands,the relative abundance of Glomus was decreased in the mixed stands,but the relative abundance of Diversispora and Claroideoglomus were increased.(3)Multiple linear regression analysis indicated that the AMF richness,Chao1 index,Shannon-Wiener and Simpson indexes were significantly affected by the soil microbial biomass C/nitrogen(N)ratio,microbial biomass N/P ratio and N acquisition enzyme activities,and the AMF richness was also significantly affected by the soil p H and microbial biomass P.Mantel test correlation analysis showed that the influencing factors of AMF community in the mixed shrub stands were less than that in the pure stands.There was a significant negative correlation between soil available P and the ratio of N and P acquisition enzymes.PLS-PM pathway analysis indicated that the main influencing factors of soil enzyme stoichiometry were soil available P and AMF diversity.(4)The height,ground diameter and nutrient concentrations of seedlings were different with shrub species.In the monoculture treatment,the height and ground diameter of seedlings were significantly increased by the inoculation treatment,but the nutrient concentrations of seedlings were not significantly affected by the inoculation treatment.The height,ground diameter and nutrient concentrations of 1-year-old seedlings were not affected by the inoculation treatment in the mixed planting treatment.(5)The soil available N,available P and soil enzyme stoichiometries were mainly affected by the inoculation treatment in the monoculture treatment.Compared with the monoculture treatment,the soil p H and microbial biomass C/N ratio were significantly reduced by the mixed planting treatment,but the glomalin-related soil protein,microbial biomass N,enzyme activities that related to C and N acquisition,and the stoichiometric ratios of P related enzymes were increased by the mixed planting treatment.(6)The effects of inoculation treatment on AMF richness and diversity indexes and community structure varied with planting patterns.Compared with the monoculture treatment,the spore density and mycorrhizal colonization rate of AMF were significantly increased by the mixed planting treatment.The AMF richness,Chao1 index,Shannon-Wiener and Simpson indexes were the highest in the C.fruticosa and S.pubescens mixed planting treatment.(7)The AMF richness and diversity indexes were significantly affected by the soil enzyme stoichiometric ratios related to N and P acquisition in the monoculture and mixed planting treatments.The influencing factors of AMF community composition in the mixed planting treatment were less than that in the monoculture treatment.PLS-PM pathway analysis showed that the main driving factors of soil enzyme stoichiometry were the shrub species and soil organic C in the monoculture treatment,but that were the AMF richness and diversity in the mixed planting treatment.(8)The soil micro-ecological environment was significantly improved by planted with C.fruticosa and inoculated with AMF in the first year,and the AMF community structure was further optimized by planted with S.pubescens in the second year.This study suggested that this planting pattern could be the optimal reference model for the vegetation restoration in Daqingshan mountains.