A Root Pull-out Test for Evergreen Broad-leaved Trees in a Coastal Forest Located on a Pebble Beach

• Published in: Journal of the Japanese Forest Society Vol. 101; no. 4; pp. 168 - 172
• Main Authors: Otani, Tatsuya, Yoneda, Reiji, Noguchi, Hironori
• Format: Journal Article
• Language: Japanese
• Published: THE JAPANESE FORESTRY SOCIETY 01.08.2019
• Subjects: Cinnamomum camphora; Morella rubra; particle size composition; tensile strength
• ISSN: 1349-8509; 1882-398X
• DOI: 10.4005/jjfs.101.168

We conducted a root pull-out test using wind-fallen Cinnamomum camphora and Morella rubra trees located on a pebble beach. The effects of root diameter and sand-pebble particle size composition on the pull-out resistance were examined. The root pull-out resistance (kN) was expressed as a power function of the root basal diameter (mm). The sand-pebble particle size composition at the locations of 14 trees subjected to the test was classified into two types by cluster analysis. The root pull-out resistance had lower values at locations with a higher proportion of pebbles sized ＞5.6 mm. There was no difference between the two species in root pull-out resistance or in root tensile strength. The parameter in the power function of root diameter and pull-out resistance in this study was smaller than those observed in previous studies conducted in a montane forest and a sand beach. This suggests a smaller pull-out resistance of tree root in coastal forests on pebble beaches with rounded gravel than in other terrains.