Abstract
Previous researches have been revealed that, in beech (Fagus crenata) forests, bad crop year likely to occur due to heavy insect attack when flower density in current year is not more than 10 times as much as those of the previous years. Thus, if the maximum flower density (Fmax) which is constant for all beech stands exists, a hypothesis can be proposed i.e. when female flower production reach up to more than 1/10 of Fmax in current year, the next year must result in a bad crop year. This suggests that we can predict the seed crop of two years later. Literature and field surveillance study investigating maximum flower and seed production in each of 25 beech forest suggested that Fmax should be 1200/m^2. Additionally, when 120 (Fmax1/10) flowers were produced, the next year tends to result in a bad crop year with high probability. This indicates that we can predict bad crop of two year later by winter bud examination, which enable us to plan more effectual forest restoration by natural regeneration or planting operation.
