Description: Since the 1950s, secondary (substitution) forests known as Satoyama woods have been abandoned due to changes in human lifestyle. The aim of this study is to investigate the relationships between human activity and substitution forests to better understand the traditional management required to prevent succession to evergreen forest. One objective is to identify the tree species, their number of trunks (NT), and the basal area (BA) (collectively, the stand density) in the woods today, half a century after people abandoned the substitution forests. Another goal is to compare, over a 6-year period, the figures for total NT, BA, and the number of living, dead or fallen trunks between an abandoned substitution forest (a control plot) and a mown plot. NT decreased from 700 to 600 trunks/ha on the control, and from 600 to 400 trunks/ha on the mown plot, at ground level over 6 years. The total BA increased annually on the control plot but decreased from 48 to 38 m 2 /ha on the mown plot over 6 years. Many hydrophytes ( Alnus japonica , etc.), Quercus serrata , and other trees species were found dead on the mown plots. All Quercus myrsinaefolia (evergreen trees) were still alive by the sixth year. These results demonstrate that the vegetation in these forests succeeded to Quercetum myrsinaefoliae , Tyoische Subass., which is therefore shown to be the potential vegetation of succession over this timescale. If it is desired to maintain the traditional vegetation type, the results of this study suggest that it is necessary to manage the substitution forest to prevent succession to evergreen forest, which could be achieved by cutting Pleioblastus chino , climbing plants, and shade plants (evergreen trees).