Application and improvement of the forecasting method of beech (Fagus crenata) crop in Yamagata [Japan] Prefecture
2009
Matsui, T.(Yamagata Univ., Tsuruoka (Japan). Faculty of Agriculture) | Koyama, H. | Ito, S. | Takahashi, N.
According to the forecasting method of beech (Fagus crenata) crop which has already been reported in Hokkaido, more than 500 of female flowers/square m are required for a stand to be good seed year. Further, percentage of predation is affected by annual increase rate of flower density between two consecutive years and insects are saturated when flower density is more than 20 times as much as those of previous year. However, whether those prerequisites would also have been applied to the other part of Japan had not been tested. In this study, we investigated flower and seed production at eleven beech stands in Yamagata, northern part of mainland of Japan during five years from 2003-2007. Seed trap data revealed that, in these study areas, only 350 female flowers/square m and 10 times annual increase rate in flower number are required to be a good seed crop. These values were lower than those of beech stands in Hokkaido. Presumably, eclosion from pupa of Pseudopammene fagivora, a main predator of beech seeds, might be prevented due to the late snow disappearing in spring. Furthermore, mass flowering with over 350/square m female flowers always resulted in more than 10 times of flower production to those of previous year. Therefore, to predict the next year's seed crop, consideration might be required only for flower density of following year which could be estimated by the winter bud investigation. Prediction of beech seed crop for Tohoku district may contribute to solve the regional unique problems including forest management (promoting natural regeneration of beech at unsuccessful artificial plantations) and wildlife management.
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