Abstract
The aim of the present study was to determine which factors affect the natural regeneration of tree species such as birch Betula spp. after clear-cutting Abies sachalinensis plantations in Hokkaido, Japan. To achieve this, the relationships between sapling density and the factors such as the presence/absence of scarification, the height of the undergrowth, and, in the case of birch saplings, the distance from adult birch trees were analyzed at five study sites. Sapling density was positively correlated with scarification and negatively correlated with undergrowth height, and scarification suppressed the height of the undergrowth. In addition, the density of birch saplings was negatively correlated with the distance from the adult trees. However, the density of birch saplings at the study sites was lower than has previously been recorded in preceding studies, indicating that the natural regeneration of this species may not be successful. This will have been due to a lower density of dispersed seeds.
