Tree-root anchorage: stability of trees based on real tree-root architecture

Abstract

Climate change impact on tree stability is often associated with higher risk of wind-throw due to higher frequency and magnitudes of the extremes of climate. Higher lateral loads due to increase in maximum wind and rainfall reduces tree anchorage due to a decrease in soil matric suction and consequently the overall strength in trunk-root-soil. This study made comparisons of the mechanical response of trees with different root architectures using static loading test conducted in the field and numerical analysis of laser-scanned root systems. For this case, Samanea saman, Khaya senegalensis and Syzygium grande were the tree species selected and analysed. The tree-root system models consisted of root system architectures obtained using 3D-laser scanning. A parametric analysis was conducted by varying the modulus of elasticity of the soil (Es) from 2.5 to 25 MPa and the results were compared with the static load tests to obtain the overall mechanical responses of the soil-tree root systems. The results showed important dependencies of the mechanical responses of the soil-tree root with the lateral load magnitudes with respect to the root architecture. The numerical models were also able to estimate the effective leeward and windward anchorage zones with different soil elastic modulus and rooting architectures to define the Tree Protection Zone (TPZ).