SPECIAL ISSUE “ Roles of revegetation for preventing Sediment Disaster ”
Relationship between tree root system and pull-out resistance under different soil conditions

Abstract

Abstract: In order to clarify the soil reinforcement ability of two tree species (Pinus thunbergii Parl. and Cryptomeria japonica (L. fil.) D. Don) , pull-out tests were carried out for evaluating the pull-out resistance of root segments of the tree species. Thereafter, we analyzed the relationship between root system parameters (i.e basal root diameter, number of branching, angle, root length, surface area, volume) and pull-out resistance. Our results suggest that the basal root diameter is the highest correlation with the pull-out resistance among parameters, and is the most suitable parameter to estimate the pull-out resistance in sites with different bulk density and soil hardness. The equations of the relationship between basal root diameter D (mm) and pull-out resistance T (N) are T＝19.4 × D ^1.5(R²＝0.716) for P. thunbergii and T＝33.6 × D ^1.5(R²＝0.792) for C. japonica.