The Effect Of Adding N And Inoculating Microbes On Plant-soil Feedback In A Sub-alpine Meadow

The feedbacks between plant and soil can promote the succession of the plant communities and restoration of the ecosystem. Plant can change the characteristics of soil, on the contrary, soil can also effect plant performance, plant productivity and population abundance.In order to provide a basis for future decisions on effective grassland restoration programs and ecosystem management, as well as for further studies on carbon cycle under global change in this and other regions, we carry out an experiment to study the effect of nitrogen fertilization and inoculating microorganisms on plant-soil feedbacks in a sub-alpine meadow. We collected soil and seeds of six individual plant species from a sub-alpine meadow ecosystem in the eastern part of the Qing-Hai Tibetan Plateau. The soil was sterilized by y-irradiation (25kGy) and germinlated seeds were transplantd. We added N (NH4NO3solution) and inoculated microbes to study their effect on plant-soil feedbacks and to test whether soil N composition control plant community succession. The results of our study showed that:(1) Plants affected the characteristics of soil in a certain species-specific way.(2) Soil C mineralization rate was positively correlated with soil microbial biomass C. Soil microbe is a major player in the soil C mineralization, and inoculating microbiology promoted the process of soil C mineralization. However, this promotion effect depended on the level of N in the soil. Our study showed that high nitrogen and high microbial had the most rapid soil C mineralization rate.(3) Different concentrations of nitrogen and differdent combination of nitrogen and microbial community both have different effects of plants. Our study showed that low nitrogen and non-microbe inoculation were favorable for plant growth, further proved that the nitrogen was the limiting factor of plant community succession in sub-alpine meadow.