喀斯特坡地2种地埂篱根-土复合体抗剪和抗冲性能综合评价

分析喀斯特地区不同地埂篱根系的形态和力学特性，量化其根-土复合体抗剪和抗冲性能的强弱，探寻该地区地埂篱根系固土抗蚀性能的评价因子，为喀斯特坡地水土流失治理中植被恢复措施的科学应用提供参考。选取重庆酉阳龙潭槽谷为研究区，分上、中、下坡分别布设拉巴豆和光叶苕子2种地埂篱，采用根系扫描仪和电子万能试验机测定其根系形态和力学参数，应变控制式直剪仪测定复合体抗剪强度，原状土冲刷水槽法测定复合体抗冲指数。结果表明：(1)抗剪复合体中，拉巴豆平均根长密度和根表面积密度分别高出光叶苕子59.32%和16.86%;抗冲复合体中，拉巴豆平均根长密度、根表面积密度和根体积密度较之光叶苕子高出30.48%、57.78%、92.98%;拉巴豆根系极限抗拉力和抗拉强度均显著高于光叶苕子。(2)2种地埂篱根系均能增强土壤的抗剪和抗冲性能，其中拉巴豆和光叶苕子复合体粘聚力较之对照土体分别增强了113.06%—124.37%和51.56%—87.12%,抗冲指数最高达到对照土体的2.81倍和2.45倍。(3)不同坡位，下坡2种植物的根长密度显著高于上、中坡；拉巴豆根系抗拉特性在下坡表现最优，光叶苕子在上坡表现更好；拉巴...

Comprehensive evaluation of shear strength and anti-scourability of root-soil complex of two grass hedgerows in karst slope land

Grass hedgerows are beneficial for preventing soil erosion on karst slopes, and their roots play a vital role. This paper aimed to analyze the morphological and mechanical properties of the root system of different hedgerows, to quantify the shear strength and anti-scourability of the root-soil complex, to explore the evaluation factors of the soil erosion resistance of the hedgerows in karst area and to provide reference for the scientific application of plant restoration measures in soil erosion control on karst slopes. Dolichos lablab L. and Vicia villosa hedgerows were planted on the upper, middle and down slopes of karst bedding slope in Youyang, Chongqing. The physical properties, root morphology and fiber content, tensile properties, shear strength index and anti-scouring index of the root-soil complex were measured. (1) The mean root length density and root surface area density of Dolichos lablab L. were 59.32% and 16.86% higher than those of Vicia villosa in the shear complex. The mean root length density, root surface area density and root volume density of Dolichos lablab L. were 30.48%, 57.78% and 92.98% higher than those of Vicia villosa in the souring complex. The ultimate tensile force and tensile strength of Dolichos lablab L. root were significantly higher than those of the Vicia villosa. (2) The roots of the two kinds of grass hedgerows could enhance the shear strength and anti-scourability of soil. Compared with the control check, the cohesion of Dolichos lablab L. and Vicia villosa complex was 113.06%-124.37% and 51.56%-87.12%, respectively, and the anti-scouring index was 2.81 and 2.45 times higher than the control check. (3) In different slope positions, the root length density was significantly higher in the lower slope than in the upper and middle slope. The tensile strength of Dolichos lablab L. root was the best in the downslope and the Vicia villosa was the best in the upslope. The cohesion and anti-scouring index of Dolichos lablab L. complex were both downslope > middle slope > upslope. (4) The principal component analysis showed that the comprehensive scores of the shear strength and anti-scourability of the root-soil complex of the two kinds of grass hedgerows were the highest in the down slope. Root surface area density, root tensile strength and root lignin content had the highest contribution to the shear strength and anti-scourability performance of the root-soil complex, which could be used as important parameters to characterize the shear strength and anti-scourability of the root-soil complex. When grass hedgerow measures are implemented in karst areas, planting on the low slope should be carried out in order to give full play to the soil and water conservation effect.