Abstract
This study analyzed slope failure recurrences and the process of revegetation in the riparian zone of the Kushira River Basin, Kagoshima Prefecture. We used data from aerial photographs and a vegetation survey. Spatial distribution of slope failure scars and tree ages in the study area were analyzed using data from nine sets of aerial photographs taken in 1947, 1966, 1974, 1980, 1984, 1989, 1994, 2000 and 2006, respectively. This analysis revealed that many slope failures occurred on steeps lopes, and that vegetation downstream of a steep slope was inundated by slope failures, debris flows and floods frequently, and vegetation with different tree ages had distributed in a patchy state in the riparian zone of the Kushira River Basin. The number of trees and tree species peaked about 20 - 30 years after an inundation by slope failures, debris flows and floods, and then declined with time. About 60 year after an inundation, an apparent fixed value was achieved. Total volume of tree trunks showed a tendency to increase after reaching a fixed value of the number of trees and tree species at about 60 year after an inundation. Moreover, the dry density of topsoil declined with time after an inundation.
https://ror.org/03ss88z23 
