AbstractGap regeneration was studied in a typical primary evergreen broad‐leaved forest without Distylium racemosum, at the Kasugayama Forest Reserve, southwestern Japan and the results were compared with those from other primary evergreen broad‐leaved forests in southwestern Japan, where D. racemosum was the dominant species. Several common types of gap regeneration behavior were recognized among the major tree species and forests with or without D. racemosum consisted of three typical regeneration guilds which could be detected in the principal component analysis. Castanopsis cuspidata frequently regenerated in gaps from saplings recruited before gap formation in the forest without D. racemosum, although elsewhere, in forests with D. racemosum, it lacked advanced regeneration and regenerated in gaps from saplings recruited after gap formation. Some evergreen Quercus had their regenerations in gaps of the forest without D. racemosum, although elsewhere, in forests with D. racemosum, evergreen Quercus might not regenerate. The results indicate that tree species may change their regeneration behavior depending on the presence or absence of another key dominant species. This suggests that the presence and the dominance of a potential competitor induces shifts in the regeneration niche of other coexisting tree species.