Root biomechanical features and wind erosion resistance of three native leguminous psammophytes for coastal dune restoration

Abstract

Taiwan is a subtropical mountainous island with fragile geological conditions and about 1566 km of coastline. Monsoon usually bring severe coastal erosion and dust storms. Canavalia lineata, Canavalia rosea and Vigna marina, three native pioneer leguminous psammophytes occurring on coastal sand dune areas, play important roles in reducing wind erosion in coastal regions. Nonetheless, its root biomechanical properties and wind erosion resistance are still unexplored. In this study, the root biomechanical properties of these plants were inspected using uprooting and tensile tests. Wind erosion resistance was estimated by wind tunnel tests. Our results showed that the growth charactersitics of C. lineata are superior than those of C. rosea and V. marina. Furthermore, the root pullout force of C. lineata (0.36 ± 0.04 kN) and C. rosea (0.36 ± 0.05 kN) are remarkably higher than that of V. marina (0.22 ± 0.02 kN). Root tensile strength of C. rosea (291.24 ± 11.89 MPa) plants is significantly greater than those of C. lineata (231.33 ± 9.47 MPa) and V. marina (95.78 ± 8.83 MPa) plants. Moreover, wind tunnel tests show that C. lineata has superior wind erosion resistance than C. rosea and V. marina. Altogether, these results clearly demonstrate that the priority species order for coastal dune restoration is: C. lineata > C. rosea > V. marina. These results contribute important strategy for ecological engineering of coastal management in sand dune areas.