Structure of primary Japanese beech ( <i>Fagus japonica</i> maxim.) forests in the Chichibu Mountains, central Japan, with special reference to regeneration processes

Abstract

Abstract The floristic composition, structure and dynamics of three primary Fagus japonica stands were investigated in the Chichibu Mountains. F. japonica was dominant [RD(%): 64.9–87.0] and showed a slightly inverse J‐shaped DBH class distribution in the quadrats [No. of canopy stems (H&gt;20m): 87–138/ha]. The stems of F. japonica for each size were distributed in the form of colonies, being scattered almost uniformly, and arranged in positive association with each other. Detailed examination of the bases of the stem groups forming colonies revealed that most of them originated from the bases of dead mother stems and that they were from common stools [No. of large stems (H&gt;10 m) per stool: 6–11]. Among six major canopy gaps observed, only one included stems sprouting from the outer part of F. japonica stools, while all the others were occupied by individuals of species other than F. japonica . After tree‐fall, several undercanopy F. japonica stems remained. Thus canopy gaps in these forest stands recovered through the sprouting of remaining F. japonica stools or by new sprouting of F. japonica individuals adjacent to the gaps. However, it was considered difficult to fill canopy gaps only with sprouts when the distance between the center of a gap and that of a stool surpasses the crown vector. Such places that are not fully occupied by sprouts will be filled by individuals of other canopy and/or under‐canopy species.