Abstract
Increasingly, recent dam projects have left forests that are above the expected normal water level. However, few researchers have investigated the changes in these inundated stands following first filling. We therefore investigated changes in the composition of the vegetation community after first filling at the Miharu Dam, Fukushima Prefecture, in the Tohoku district of Japan. This research was conducted on transects established in a forest dominated by Castanea crenata and Quercus serrata. A survey conducted in the year following first filling revealed that trees that were submerged for 53 days died. Significant changes were observed in the vegetation community in the lower parts of the slope, between EL. 326.0 and 329.0m, in areas that were submerged for about 37 days. Pioneer species such as Rubus crataegifolius increased in areas with decreased canopy cover. The main factor contributing to the changes in the community composition was probably the change in light conditions following the death of trees. The upper 4m (EL. 329.0-333.0m) of the 7m slope affected by first filling were inundated for less than 37 days. All trees in this area survived, and only minor changes were observed in the shrub and herb layers, suggesting that the forest was preserved.
