ツガ天然林の更新 : IV.久保谷山周辺の温帯針葉樹林植生

抄録

The forest vegetation of Kubotani-yama area (Kochi Pref., Shikoku) consisted of six main types, of which three dominated by Tsuga covered 88% of the whole area (471 ha). It was found that 85-87% of number of tall canopy trees in Tsuga forests germinated during a single regeneration period of about 70 years brought about by extensive forest disturbance due to the visit of a big typhoon some 260 years ago. Remaining 13-15% are older trees which survived the typhoon. Seedling regeneration in newer and smaller wind-gaps was also detected, but not very frequent. Pinus densiflora stands were found in a limited area on relatively gentle slopes and presumably originated from old fields of shifting cultivation which prevailed in this district in former times. There was also some evidence of selective logging of Chamaecyparis obtusa trees more than 100 years ago. Otherwise the area remained almost intact, and the wind disaster 2.6 centuries ago played an decisive role in the development of present-day forest vegetation.