厳島(宮島)におけるモミ林の成立過程の考察 <論文>

Abies firma has still been controversial whether it is a climax forest species in the warm temperate region or not. This is because that in the warm temperate, the species is merely seen except in the remnant forest patches such as in the shrine gardens. Towards this question, we surveyed its distribution in a part of Itsukushima Island, Hiroshima Prefecture. In our observation, the mature trees with reproductive size (35 cm < D) were found mostly in valley bottom, while they were much less abundant in the ridge tops of the study site. Contrary to this, saplings (D < 1 cm) were much less in the valley bottom while these tree size classes are quite abundant in the ridge tops. Light environment in the valley bottom was very low in comparison to the ridge top due to the dense canopy. However, even in the valley bottom, middle size (1 ≤ D ≤ 35 cm) trees are quite abundant in the vicinity area of check dam where the vegetation was once opened for its construction. These fi ndings imply ecological characteristics of A. fi rma as a secondary species, namely, unless any disturbance happen occasionally, it can not continuously regenerate in the study site.