| Vegetation restoration is one of the most effective ways to control soil erosion.The study of the changes in vegetation root systems and soil properties under different vegetation restoration modes and their impact on soil erosion processes is of great theoretical significance for the improvement of the red soil slope erosion theory and the allocation of vegetation restoration measures.This study takes five typical vegetation restoration modes in the southern red soil erosion area as the research object and uses bare land as the control.Soil samples were collected from six different vegetation restoration sites and washed in a slope variation water tank system.At the same time,soil physical and chemical properties and root system indicators were measured to quantitatively analyze the effects of root characteristics and soil properties under different vegetation restoration modes on soil erosion resistance in the red soil erosion area.The main conclusions are as follows:(1)The soil structure of different vegetation restoration sites has been effectively improved,with a decrease in soil bulk density and an increase in porosity.The soil shear strength,MWD,and organic matter content have all been effectively improved.Different vegetation restoration sites have different root characteristics.The grassland has the highest root length density,surface area,volume,mass density and root length density and root surface area of the diameter class D≤0.5mm.However,in terms of root volume density in different diameter classes,the forest has the largest root volume in the diameter class D>1mm.(2)In the vegetation root index,root mass density is the dominant factor of soil bulk density,porosity and MWD,root volume density of D > 1 mm diameter is the dominant factor of organic matter,root volume of 0 < D ≤ 0.5 mm diameter is the dominant factor of soil clay,silt and sand,root length density is the dominant factor of soil shear strength.(3)The soil detachment capacity and rill erodibility of different vegetation restoration sites showed different degrees of decline compared with bare land,and the soil critical shear force showed different degrees of increase.The critical shear stress of soil increased exponentially with the increase of soil bulk density and MWD,and decreased linearly with the increase of soil porosity,but had no correlation with vegetation roots.The soil rill erodibility decreased linearly with the increase of root mass density,decreased exponentially with the increase of soil bulk density and MWD,and increased exponentially with the increase of soil porosity.(4)Bare land,farmland,and orchards with no cover are more vulnerable to erosion,while soil in forest land,orchards with grass cover,and grasslands soils are basically not stripped.The soil separation ability decreased exponentially with the increase of root mass density,soil bulk density,organic matter content and MWD,decreased linearly with the increase of root surface area density and root volume density,and increased exponentially with the increase of soil porosity.The root mass density in the root index and the soil MWD in the soil physical and chemical properties index were the dominant factors of soil separation ability,and the effect of root mass density on soil separation ability was greater than that of soil MWD.In addition,a soil detachment capacity prediction model based on shear stress,root mass density,and soil MWD was established with good prediction performance(R2=0.95,NSE=0.92).It can be seen from the above that increasing the mass density of vegetation roots and improving the stability of aggregates can effectively reduce the soil separation ability.Therefore,in the process of vegetation restoration,reasonable ground cover management measures should be adopted,such as planting suitable herbaceous plants in orchards or woodlands,and no-tillage,less-tillage,or straw mulching in sloping farmland to improve root distribution and aggregate stability and control soil loss. |
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