Root Distribution and Root Cohesion of Two Herbaceous Plants in the Loess Plateau of China

In order to understand the root morphology distribution and mechanical properties of typical herbaceous plants, and to evaluate the ability of soil reinforcement by the plant roots, root morphology investigation, single root tensile test in laboratory and root cohesion evaluation by the Wu-Waldron model were carried out on two local representative herbaceous plants, Kochia scoparia (L.) Schrad and Artemisia sacrorum Ledeb. in the Loess Plateau of China. The results showed that the root morphological indexes (root number, single root diameter, root cross-sectional area, root surface area, root volume and root area ratio) of the two herbaceous plants decreased with the increase in soil depth, and the ratio of root to shallow soil layer was the highest in the 0-10 cm soil layer. The efficiency of root reinforcement could be higher in the shallow soil layer less than 10 cm. A positive correlation was observed between the root tensile force and root diameter in power function or exponential function, and a negative correlation was observed between the root tensile strength and root diameter in power function. The root cohesion of Kochia scoparia (2.73 kPa, or 0.92 kPa-1.37 kPa) was greater than that of Artemisia sacrorum (1.60 kPa, or 0.54 kPa-0.8 kPa), which could be used as the preferred herbaceous plant species for soil erosion control. The results could provide a scientific basis for selecting dominant species in the fields of ecological slope protection and soil and water conservation plant engineering in the loess area.