Annals of Botany 78: 741-748, 1996
© 1996 Annals of Botany Company
Recruitment Processes and Species Coexistence in a Sub-boreal Forest in Northern Japan
The Institute of Low Temperature Science, Hokkaido University, Sapporo, 060, Japan
February 5, 1996 ; June 28, 1996
We investigated the recruitment of saplings (across the 2 m-height threshold) of six species,Picea jezoensis, Abies sachalinensis, Betula ermanii, Picea glehnii, Acer ukurunduense andSorbus commixta, in a sub-boreal forest, northern Japan. Data were collected in a 2.48-ha plot over six growing seasons (1989–1994). We used path analysis to analyse the relationships between the recruitment rates of saplings and the stand structural attributes such as mother tree abundance, stand crowdedness, stand stratification,Sasa bamboo density on the forest floor, and fallen log abundance. The combination of stand structural attributes affecting recruitment rates of the six sub-boreal forest tree species differed markedly among the species and corresponded to species composition. It is suggested that the size-structure dynamics of adult trees of the sub-boreal forest are regulated largely by different regeneration processes among the species and only slightly by interspecific competition between adult trees because interspecific competition between adult trees was not evident. The dynamics of species coexistence of the sub-boreal forest should be described as a process combining the diversity of recruitment processes of saplings of the component species and the diversity of interspecific competition between adult trees. We propose the boundary condition hypothesis for species coexistence in the sub-boreal forest, that the persistence of each component species is ascribed largely to the different recruitment processes of saplings (boundary conditions for adult tree growth dynamics) and only a little to interspecific adult tree competition.
Climax forest; safe site; regeneration niche; mode of competition; species diversity