Distribution Characteristics Of Shear Strength Of Root Soil Complex Of Natural Communities And Potential Slope Protection Plants In Loess Area

The root morphology and mechanical properties of plants are important factors affecting the function of slope protection.Through the spatial distribution characteristics of plant root morphology in soil and the characteristics of root tensile resistance,we can better understand the mechanical effect of plant root slope protection,which has an important theoretical reference value for the research of shear strengthening effect of root soil composite,and provides a theoretical guidance for the selection and spatial allocation of slope protection plants.In order to explore the mechanical effect of local plants on slope protection in the loess area,three natural communities,i.e.Bothriochloa ischaemum,Lespedeza davurica and Hippophae rhamnoides,and individual plants of two kinds of plants,i.e.Sophora viciifolia and Stipa bungeana,were selected in this experiment.The root soil composite samples were collected layer by layer by three-dimensional coordinate soil column sampling method,and the root samples were taken after soil removal and root cleaning to determine the shear strength of the root soil composite and its application in the soil The relationship between the shear strength of root soil complex and the parameters of root morphology was calculated and analyzed.The main results are as follows:(1)The root distribution indexes of three natural communities in loess area,such as the root length density,root surface area density and root biomass density,decreased with the increase of soil depth.In individuals,the root length density and root surface area density were concentrated in 0-30 cm soil layer and 40 cm away from the main root;the root length density was concentrated in 0-20 cm soil layer and 25 cm away from the main root.(2)With the increase of root diameter,the maximum tensile strength of the roots of Bothriochloa ischaemum,Lespedeza davurica,Hippophae rhamnoides,Sophora viciifolia and Stipa bungeana increased linearly;the root elongation of Bothriochloa ischaemum,Lespedeza davurica and Hippophae rhamnoides increased linearly with the increase of root diameter.With the increase of root diameter,the tensile strength of the roots decreased.(3)With the increase of gravity load and root biomass,the shear strength of the natural communities of Bothriochloa ischaemum,Lespedeza davurica,Hippophae rhamnoides and individual plant root soil complex increased gradually,and decreased with the increase of soil water content.The shear strength of root soil complex decreased with the increase of soil depth.Among them,the shear strength of the root soil complex in the rhizosphere of the spike is mainly in the depth of 0-60 cm soil layer,which is 1.5 times higher than that of the plain soil;the shear strength of the root system of Stipa bungeana is mainly in the depth of0-40 cm soil layer,which is 1.1 times higher than that of the plain soil.Therefore,through the study and analysis of the spatial distribution characteristics of root system,the tensile properties of single root and the shear strength characteristics of root soil complex of the three natural communities of Bothriochloa ischaemum,Lespedeza davurica and Hippophae rhamnoides,as well as the individual plants of Sophora viciifolia and Stipa bungeana,it can provide a reasonable theoretical basis for enhancing the stability of slope and selecting the appropriate types and configuration of slope protection plants.It has certain guiding significance.