Study On Plant-soil Feedback Of Different Functional Groups Of Plants In Songnen Grassland

Since the proposal of plant-soil feedback,the interplay and interdependence between the aboveground and underground has been gradually recognized and now been a research hotspot among ecologists due to its significant contribution to the research on maintaining the structure and function of ecosystem.However,this conception,if applied alone,has limitions on the study of grassland,a key component of terrestrial ecosystem,considering the rich variety of plant species hereof.Therefore,a combination of plant functional groups with plant-soil feedback is suggested,which can simplify the complexity of grassland ecosystem and facilitate understanding on the interaction between grassland plants and soil.There have been little systematic study on the plant soil feedback or its inherent response mechanism among different plant functional groups so far.Meanwhile,most studies done focused on the monoculture level,only few under the community conditions,which has limited our ability to predict the feedback between species and communities.In this study,four main plant functional groups in Songnen grassland were selected as the research subject,and two pot experiments of single species and mixed species were set up to study the effect and response of plant functional group growth on the change of soil and microbial characteristics by two ways sterilization and non sterilization.The research conclusions indicated that:(1)There are significant differences in the plant-soil feedback effect between the main plant functional groups in Songnen grassland.At monoculture,Leymus chinensis,the C3 plants of Gramineae and Artemisia scoparia,the forbs,received negative feedback from other plants,and positive feedback acted on Chloris virigata,the C4 plants of Gramineae and Melilotus suaveolens,the leguminous plant.While there was negative feedback between C.virigata and M.suaveolens.When the soil microbial community regulated by plant specificity was removed,the feedback effect of C.virigata was changed from positive to negative,and the negative feedback to M.suaveolens was also changed to positive.Compared with the monoculture,the positive feedback effect between plant functional groups increased after mixed cropping,and only L.chinensis was significantly negative feedback.(2)According to the results of correlation and redundancy analysis between the growth characteristics of plant functional groups and soil physical and chemical properties,it is found that nitrate nitrogen and soil available nitrogen are the main factors affecting plant growth,indicating that soil nitrogen may be a potential factor affecting plant-soil feedback between different plant functional groups.Because the direction of feedback effect has changed after the removal of microbes,it indicates that soil microbes may also be the influencing factors of feedback.(3)Plant-soil feedback significantly changed the physical and chemical properties of soil in different plant functional groups,and these changes were also significantly different due to different plant functional groups.Compared with the blank control,the change of soil available nutrients was more obvious than that of mineral nutrients,except ammonium nitrogen,nitrate nitrogen and soil available nitrogen decreased significantly.(4)In the plant-soil feedback process,the feedback effect of soil on plants leads to significant differences in biomass of different plant functional groups.Compared with native soil,the biomass of L.chinensis decreased significantly in the soil of C.virigata and M.suaveolens.The biomass of C.virigata increased significantly in the soil of L.chinensis and A.scoparia.The biomass of M.suaveolens increased significantly in the soil of L.chinensis and A.scoparia,decreased in the soil of C.virigata most.The biomass of A.scoparia decreased significantly in the soil of other plants.In summary,this paper elaborates the plant soil feedback relationship of the main plant functional groups in Songnen grassland.The study of the effect of plant growth on soil and microbial characteristics reveals the potential influence factors of soil and microbial characteristics on plant characteristics in the process of plant-soil feedback.According to the response characteristics of different plant functional groups to soil feedback,the theory of "bottom-down" is proved again.In addition,the plant-soil feedback effect value and the net pairing feedback value between the two groups are used to explain the competition between the functional groups of plants,which enriches the theoretical knowledge of plant-soil feedback in the process of succession of functional groups of plants.At the same time,it also provides a theoretical reference for the study of the circulation process of mineral nutrients in the plant microorganism soil system and its influence during the succession of plant functional groups.