Spatial pattern dynamics over 10 years in a conifer/broadleaved forest, northern Japan.

摘要

The present study investigated stand dynamics during 10-year period in a conifer/broadleaved mixed forest in Hokkaido, northern Japan, focusing on spatially dependent recruitment, mortality and growth of two growth-form groups, deciduous broadleaved species and the dominant evergreen conifer Abies sachalinensis. The stand-level basal area was maintained over the 10-year period, while a compositional equilibrium at the individual species level was not confirmed. Univariate and bivariate spatial analyses revealed clustering of many of the constituent species. The absence of single-species patches suggested an ambiguous mosaic formed by co-occurrence of Abies and broadleaved trees. The trend towards an aggregated distribution of Abies and broadleaved trees was caused by spatially dependent recruitment rather than mortality. New recruits of broadleaved species were spatially associated with surviving broadleaved trees, while this was not the case for Abies. The degree of competitive effects on growth was not consistent over the 10-year period. Abies showed between-groups competition, but not within-group competition. In contrast, we found asymmetric competitions between the broadleaved trees. Our results suggest that Abies is not sufficiently competitively dominant to exclude broadleaved trees, and that the co-occurrence of the two growth-form groups might be maintained..