Responses Of Arbuscular Mycorrhizal Fungal Community And Nitrogen Absorption Function To Fertilization In Qinghai-Tibetan Alpine Meadow

Alpine meadow is a special kind of grassland.Global changes and human activities had caused a large degradation in Qinghai-Tibetan alpine meadow.Nowadays,fertilization is a common method used in Qinghai-Tibetan plateau area for grassland restoration.Arbuscular mycorrhizal fungi(AMF)can associate with most terrestrial plants,improve their nutrient uptake in exchange of carbon.Besides,AMF can regulate the plant population,community and ecosystem.Therefore,it's of great significance to study the AMF community and function in Qinghai-Tibetan alpine meadow.In one part of this study,we analyzed the responses of AMF community composition to nitrogen(N)and phosphorus(P)addition and investigated the environmental factors which drove the differences among the AMF community distribution based on field sampling and high throughput sequencing in Qinghai-Tibetan alpine meadow.In another part of this study,we calculated the relative N absorption contribution of AMF to Kobresia.pygmaea and analyzed the effects of N addition on this contribution based on field compartment mesh experiment and in situ 15N labeling in this meadow.As a result,we found that(1)N and P addition increased soil ammonium(NH4-N)&nitrate(NO3-N),total phosphorus(TP)&available phosphorus(AP),respectively.(2)N and P input had no effect on AMF colonization,OTU richness or diversity.(3)N and P addition had no effect on AMF community composition.However,soil organic carbon(SOC)and NO3-N were significantly positively correlative with AMF community composition.(4)SOC,NO3-N,TP and AP had positive correlation with AMF community distribution.SOC was the most correlative factor,which impact AMF community in low P condition while NO3-N,TP and AP influenced AMF community in high P condition.(5)The relative N absorption contribution of AMF to Kobresia.pygmaea on alpine meadow was 48.2%and was not affected by N input.