秩父山地イヌブナ(Fagus japonica MAXIM.)天然林における堅果落下量と実生の消長

概要

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The fall of nuts and cupules and the survival of seedlings was studied in a natural beech forest in the Chichibu Mountains of Central Japan for three years (1984-1986) to clarify the regeneration dynamics of Fagus japonica MAXIM. The density of nut fall varied greatly from 310±99.64 nuts/m^2 in 1984 (a good mast year) to 0.08±0.16 nuts/m^2 in 1985 (a lean year). In 1984,the nut fall of F. japonica was not concurrent with that of the F. crenata in the same stand, and the ratio of sound nuts (31.9%) was nearly half of the sum of the percentages of empty husks and nuts damaged by insects, mammals and birds (39.8%, 15.5%, and 12.9%, respectively). Only 1.05% of the fallen sound nuts germinated, resulting in a density of 1.04 seedlings per 1.0m^2 in the following spring. A large number of the seedlings (about 98.6%) were infested by aphids (Phyllaphis fagi L.) and died by the end of June. The large variation in frequency and quantity of nut fall and the high mortality of seedlings suggest that the maintenance of seedling banks under the F. japonica canopy is tenuous. The successful regeneration of F. japonica forests is discussed, noting the relationships between seedling production, canopy gap formation, and sprouting.
日本生態学会の論文
1989-04-30