Root morphological and mechanical properties of Lespedeza bicolor Turcz. on slopes at different altitudes

Key message

Root morphology and tensile strength were affected by elevation, with changes in the former showing adaptation to the environment, and changes in the latter mainly influenced by root chemical composition.

Abstract

Plant roots have absorption and anchorage functions and play important roles in plant growth and slope stability. Root morphology and mechanics are closely related to root function and are influenced by various factors. However, the impact of elevation, which encompasses a range of environmental changes, has not been fully studied. This study aimed to investigate the responses of root morphology and root mechanics to environmental changes associated with elevation and to explore the possible effects of these responses on root reinforcement. We measured the morphological properties (length, diameter, and number), tensile strength, and chemical composition (cellulose, hemicellulose, and lignin contents) of the taproots and first- and second-order roots of Lespedeza bicolor Turcz. grown at three different elevations (986, 1839, and 2716 m). The lengths of both taproots and lateral roots decreased, while the diameter of lateral roots increased with increasing elevation. Additionally, there was a significant increase in root tensile strength as elevation increased, accompanied by an increase in cellulose content and a decrease in lignin content. Root tensile strength correlated positively with cellulose content and negatively with lignin content. The morphological and mechanical properties of L. bicolor roots are significantly influenced by elevation. Roots exhibit adaptive strategies in response to environmental factors such as hydrothermal conditions and soil nutrient availability. Cellulose and lignin have a significant impact on the biomechanical properties of roots. Regarding soil reinforcement, roots at lower elevations exhibit a more advantageous morphology. Conversely, roots at higher elevations possess greater biomass and tensile strength, making them more resistant to soil erosion under extreme environmental conditions.