Studies On Soil Feedback Of The Invasive Plant Alternanthera Philoxeroides

The invasion of alien species threatens global ecological security and agricultural security,causing huge economic losses.Soil organisms play an important role in the process of plant invasion.For example,plants can change the structure of soil biological communities,thereby regulating plant growth in the later period,that is plant-soil feedback.In this paper,the invasive plant Alternanthera philoxeroides was taken as the object,and the native plant Alternanthera sessilis was used as a reference to explore the regulation effect of plant-soil feedback on the invasion of A.philoxeroides.The research results are as follows:(1)With the increase of planting density,the plant root biomass,shoot biomass,total biomass,plant stem length of the invasive plant A.philoxeroides and the native plant A.sessilis increased significantly;The Beta diversity of the arbuscular mycorrhizal fungi of the invasive plant A.philoxeroides rhizosphere increased,while the Beta diversity of pathogenic fungi of the native plant A.sessilis rhizosphere increased.(2)The soil organisms invaded and domesticated by domestic plants significantly inhibited the growth of plants in the later period(ie,negative feedback of soil),and the negative feedback effect of the native plant A.sessilis on its own was significantly higher than that of A.philoxeroides.Soil organisms improved the suitability of of Agasicles hygrophila larva feeding on the leaves of A.sessilis,but had no significant effect on the suitability of A.hygrophila larva feeding on the leaves of A.philoxeroides.It shows that soil bioenergy can directly inhibit the growth of native plants or increase the risk of native plants being fed by insects,and promote the invasion of A.philoxeroides.(3)The feedback of soil organisms to invasive and native plants,and leaf-eating insects that feed on two plants is related to the occurrence of different fungi.The feedback effect of the soil on the shoot biomass of the native plant A.sessilis decreased with the increase of the occurrence of Powellomyces;the feedback effect of the soil on the biomass of the A.hygrophila feeding on the invasive plant A.philoxeroides increased with the increase of the occurrence of Gibellulopsis;the feedback effect of the soil on the biomass of A.hygrophila feeding on the native plant A.sessilis increased with the increase of the occurrence of arbuscular mycorrhizal fungi.(4)Compared with the native plant A.sessilis,the invasive plant A.philoxeroides has a more developed root system and a higher root-to-shoot ratio,and has a higher tolerance to biological(such as insect feeding)and abiotic(such as drought)stress.These traits may also promote their invasion.In summary,soil organisms can directly or indirectly improve the competitiveness of A.philoxeroides against to native plants;the more developed root system and higher root-to-shoot ratio make the A.philoxeroides highly resistant to biological and abiotic stresses,this may jointly promote the invasion of A.philoxeroides.This study provides good practical and theoretical support for further understanding of the interaction of soil organisms with A.philoxeroides and environmental factors on A.philoxeroides,and provides a useful reference for the study of other invasive plants.