Estimation of lateral root reinforcement in sugi [Cryptomeria japonica (L.f.) D. Don] and hinoki [Chamaecyparis obtusa (Siebold et Zucc.) Endl.] plantations using a root bundle model with Weibull survival function

Abstract

To effectively implement forest management designed to enhance the shallow landslide prevention function on forest slopes, it is important to correctly evaluate lateral root reinforcement. In this study, I estimated the lateral root reinforcement of sugi and hinoki plantations using a RBMw. Root pullout tests were conducted on lateral roots, and pullout force and displacement were measured. The results obtained were used to calculate parameters adopted for the RBMw, and root reinforcement was estimated by applying the model to the lateral root distribution data. Using this approach, estimated values of 6.0 and 6.8 kN/m² were obtained for the sugi and hinoki plantations, respectively, which were 43% and 46% of the values estimated using the conventional (Wu model) method. It is necessary to verify the results with actual measurements.