Responses Of Arbuscular Mycorrhizal Fungi Community To Precipitation Changes And Nitrogen Deposition In Stipa Breviflora Desert Steppe

The desert steppe ecosystem plays an important role in terrestrial ecosystems.As an important feature of global change,precipitation change accompanied by nitrogen deposition affect the function of desert steppe ecosystem by regulating soil microbial community.This study was conducted to investigate the response of arbuscular mycorrhizal fungi to precipitation and nitrogen deposition in an attempt to comprehensively and systematically analyze the impacts of global changes on desert steppe ecosystems.The results provide important theoretical and practical significance for formulating scientific management countermeasures.This study was carried out at field control experiment of Stipa breviflora desert steppe site to investigate the response of AMF community to precipitation and nitrogen deposition in desert steppe.A split-plot experimental design was used with main plots natural rainfall（CK）,rainfall increase 30%（W）and rainfall decrease 30%（R）as well as submain plot 4nitrogen treatments 0（N0）,30（N30）,50（N50）and 100（N100）kg·hm^-2·a^-1,respectively.The main results are as follows:（1）Precipitation changes and nitrogen deposition altered AMF community in desert steppe.Rainfall increase has a promoting effect on the alpha diversity of AMF.Alpha diversity showed a trend of W>CK>R under the same nitrogen addition conditions.rainfall Decrease rainfall is the opposite.Nitrogen addition reduced the alpha diversity of AMF,with the highest Shannon index in CK-N0 which significantly decreased the alpha diversity of AMF 6.28%compared to CK-N0.The interaction between nitrogen deposition and precipitation changes has a antagonism effect.The Ace index in W-N100 increased by3.63%compared to CK-N0.At the same time,the interaction between water and nitrogen promotes significant changes in the community composition and Beta diversity of AMF.Whether nitrogen deposition reduces AMF diversity mainly depends on water content,and the negative effects of nitrogen deposition become stronger as the drought increases.（2）Soil and vegetation factors were changed significantly in the precipitation changes and nitrogen deposition scenarios.Rainfall increase has a positive compound effect on plant community diversity and aboveground biomass accumulation under nitrogen addition.Precipitation changes and nitrogen deposition have a significant impact on soil enzyme activity.The soil catalase activity was lowest in R-N100 and reduced significantly by 8.0%compared to CK-N0;The soil sucrase activity was highest in W-N0and was significantly increased by 13.76%,while was lowest in R-N100 and was significantly decreased by 17.46%compared to CK-N0;The soil urease activity is highest in W-N0 and was significantly increased by 21.47%,while was lowest in CK-N100 and significantly decreased by 37.18%compared to CK-N0.（3）Nitrogen deposition increases soil nitrate nitrogen content,and the drier the soil,the more nitrate nitrogen accumulates.The interaction between rainfall increase and nitrogen deposition is beneficial for plant community diversity and aboveground biomass accumulation,and the two have a synergistic effect.