Role of Uprooting in Composition and Dynamics of an Old‐growth Forest in Japan

Abstract

Seedling, sapling, and tree composition in several types of gap and nongap microsites were examined in an old—growth temperate mixed forest in western Japan. The distribution of species was not related to gap size (10—340 m²). Seedling communities on tip—up mounds and those on fallen boles of coniferous trees were rich and composed of pioneer species. In contrast, understory composition in gaps without uprooting did not differ from undisturbed forest. Dwarf bamboo, which dominates the forest floor and prevents tree regeneration, magnifies the effect of uprooting. Species with small, wind—dispersed seeds were found mainly on disturbed soil, while species with large, animal—dispersed seeds did not have any bias in distribution. Soil disturbance is a more important feature of the disturbance regime of this forest than is gap formation, with regards to maintaining species richness.