A Biomechanical Study of Potential Plants for Erosion Control and Slope Stabilization of Highland in Thailand

Soil bioengineering provides a sustainable method for erosion control and soil slope stabilization using vegetation with multiple co-benefits. This study evaluated ten plant species in Thailand’s highland regions for their soil bioengineering potential and additional benefits. Root architecture, tensile strength, and Young’s modulus were measured to compare biomechanical traits. G. sepium, F. griffithii, P. americana, B. asiatica, and C. arabica exhibited H-type roots with wide lateral spread, while M. denticulata and C. officinarum had VH-type roots with deep taproots and wide lateral extent. A. sutepensis showed M-type roots with most root matrix in the top 0.3 m, where C. cajan and C. sinensis had R-type roots with deep, oblique growth. Most species showed a negative power relationship between the root strength and Young’s modulus with the root diameter except C. cajan that showed a positive correlation. P. americana, F. griffithii, C. officinarum, and C. arabica showed relatively high values of 1 mm root tensile strength (exceeding 24 to 42 MPa), while M. denticulata, G. sepium, and B. asiatica exhibited intermediate root tensile strength (ranging from 8 to 19 MPa). A. sutepensis, C. cajan, and C. sinensis demonstrated the lowest root tensile strength, up to 7 MPa. It is advised to plan slope vegetation by selecting diverse plant species with varying root structures and benefits, addressing both engineering and socioeconomic needs of the sustainable nature-based solution.