Regeneration Traits of Four Dominant Species in a Cool-Temperate Conifer-Hardwood Mixed Forest, Northern Japan

Abstract

Regeneration traits of four dominant species were studied during a decade in a cool-temperate conifer-hardwood mixed forest, northern Japan. Dominant species were three canopy species (Tilia japonica, Acer mono and Abies sachalinensis) and a subcanopy species Prunus ssiori. Regeneration traits differed among the four dominant species. The regeneration of a conifer Abies sachalinensis largely depends on major disturbances because its size structure was a bell-shaped pattern. The growth rate of the sub-canopy species Prunus ssiori increased faster with tree size than the other three species, and therefore, this species can reach reproductive stage faster. Although the number of recruits of Tilia japonica was less than the other three dominant species, about one-fourth of Tilia japonica regenerated by the sprouts. Thus, vegetative reproduction is important for the regeneration of Tilia japonica. On the contrary, many recruits were observed in Acer mono, and its recruits and saplings concentrated in canopy gaps, suggesting that the regeneration of Acer mono restricted to canopy gaps. Thus, clear differences in the regeneration traits were recognized in the four dominant species. This study suggests that the species-specific regeneration traits contribute to the species coexistence of the four dominant species through different regeneration niches.