Study On The Soil Conservation And Slope Reinforcement Performance Of Three Southwest Mountain Pioneer Plants Based On Vegetation Concrete Technology

Appropriate pioneer species and planting density are the key factors affecting the effect of vegetation concrete ecological protection technology on soil and slope protection.To study the soil reinforcement and slope stabilization properties of southwest alpine pioneer plants in the application of vegetation-concrete structures,Elymus nutans,Festuca elata,and Poa annua were planted on the vegetation concrete substrate with the same density,and the plant growth indicators and soil slope protection performance indicators were measured,to reveal the differences in soil and slope protection performance of three mountain pioneer plants.Then,we took Elymus nutans as an example,set control,Ⅰ(1100 seeds/m~2),Ⅱ(2200 seeds/m~2),Ⅲ(3300 seeds/m~2),Ⅳ(4400seeds/m~2)andⅤ(5500 seeds/m~2)six seeding density treatment levels on the vegetation concrete substrate,the plant growth indicators and soil reinforcement and slope stabilization performance indicators of each treatment level were measured,and the correlation between the indicators was analyzed to reveal the sowing density on vegetation concrete impact of slope protection performance.The results were as follows:Plant species had an important effect on the slope protection performance of vegetation concrete.The growth conditions of the three plants on the concrete substrate of vegetation were significantly different.Among them,the number of tillers of Poa annua was the largest,and the root surface area and average root diameter of Festuca elata were the largest,the plant height,aboveground and underground biomass,and root length of Elymus nutans were the largest.Three kinds of plants had different interception effect on stems and leaves,and Elymus nutans had the best interception effect.Among them,the largest interception amount was Elymus nutans and the lowest was Poa annua,the maximum interception rate was highest in Elymus nutans and lowest in Festuca elata.Three plants significantly enhanced the scour resistance,erosion resistance,and shear strength of the vegetation concrete substrate.Compared with the blank control,the scour resistance increased by 103.28%～267.99%,the erosion resistance increased by 25.15%～84.00%,and the shear strength increased by 8.45%～18.04%.Among them,the scour and erosion resistance enhancement coefficient of Festuca elata root-soil complex was the largest,and the shear strength of Elymus nutans root-soil complex was the largest.Root surface area and root diameter were the key factors affecting scour resistance and erosion resistance,and shear performance was closely related to underground biomass and root length.The principal component analysis method was used to comprehensively evaluate the slope protection performance of three kinds of plants.The comprehensive evaluation of principal component analysis showed that the soil reinforcement and slope stabilization performance of the three plants was the highest in Festuca elata,followed by Elymus nutans,and the Poa annua worst.As density increased,aboveground biomass continually increased,and plant heights,root surface areas,root lengths,and underground biomass all first increased and then decreased.In contrast,tiller numbers and the average root diameter gradually decreased with increasing density.Increased density also resulted in increased maximum water interception levels by aboveground stems and leaves.The maximum water interception by the aboveground stems and leaves was 41.75%greater in the highest density treatment(V)compared to the lowest density treatment(I).However,the enhancement of erosion resistance and soil shear strength first increased and then decreased as density increased,with maximal values observed in the medium-high density treatment(IV).Sowing density was highly correlated with aboveground biomass,plant heights,tiller numbers,and the maximum level of water interception by stems and leaves.Thus,sowing density directly influenced soil reinforcement and slope stabilization properties of aboveground plant components.However,density was not significantly correlated with underground biomass,root lengths,root surface areas,the enhancement of erosion resistance,and soil shear strengths.Therefore,sowing density indirectly influenced soil reinforcement and slope stabilization of underground plant components.Following from these results,we suggest that the optimal sowing density of Elymus nutans is approximately 4400 seeds/m~2in their application within vegetation-concrete structures used for slope protection.