Japanese maple (Acer palmatum var. Matsumurae, Aceraceae) recruitment patterns: seeds, seedlings, and saplings in relation to conspecific adult neighbors.

We analyzed the spatial patterns among seeds, seedlings, saplings, and conspecific adult trees of the cool-temperate tree species Acer palmatum var. Matsumurae in a conifer-hardwood mixed forest in northern Japan, using two models that consider the influence of each adult within the neighborhood of the offspring. The results showed that recruitment patterns of each stage could be characterized and that significant shifts occur between successive stages. Sound seeds were more widely dispersed than unsound seeds; the mean dispersal distance (MDD) was 41.5 m for sound seeds, but only 12.6 m for unsound seeds. Most seedlings were located near conspecific adult trees, with a MDD of 14.3 m. Saplings, however, were more dispersed away from conspecific adult trees, with an MDD of more than 35 m. Light and gap distributions did not strongly affect the spatial distribution of the offspring; most saplings were located under nonconspecific canopies. These results suggest that the recruitment pattern of Japanese maple offspring is strongly affected by conspecific adult neighbors, rather than by light and gap distributions, with close proximity to conspecific adult trees reducing the growth and survival of seedlings during the transition to saplings.