In Mie and Fukui prefectures, many slope failures occurred in the forest slopes caused by heavy rainfall in 2004. The influence of standing trees for failed sediment was discussed. Study sites were located in former Miyagawa village in Mie prefecture and Miyama town in Fukui prefecture. The depth and width of slope failures, sedimentation stopped by the standing trees or flowing down through the stands were investigated by field surveys in each forest slope. In the case of slope failures of smaller than a10meter width, the ratio of slope failure areas were high at the younger stands, around5to15years old, for both sites. Also, the relationship between slope width and slope depth was found as follows. In the case of sedimentation, when the slope failures were small, the diameter at breast height of standing trees was large. When the slope failures were large, the diameter at breast height of standing trees was small in case of flowing down. The data of both cases were classified by discriminant analysis using factors of the diameter at breast height and slope failure depth.

Key words�Fslope failure, failed soil, sediment to standing tree, depth of slope failure, diameter at breast height