The investigation for the conservation of the Fagus crenata forest in southern limit of distribution area

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The structure of beech (Fagus crenata) stands and the regeneration regimes of beech were investigated at the ridge in Mt. Takakuma, which is the southern limit of beech distribution.(1) The height of beech in Takakuma is suppressed compared with the radial growh or the horizontal extension of the crown when the beech was taller than the shrub layer. Poor dominance of canopy tree species may be an indirect reason for such a change in the trade-off relationship between vertical and horizontal growth. However, although the height of beech in Takakuma was suppressed, death of beeches or obvious declines of radial growth were not observed.(2) The density of the basal area and beech trees in Takakuma was as low as that of other Pacific Ocean type beech forests. The proportion of small trees with <10cm in Dbh to canopy trees with >20cm in Dbh was lower in 0.5. Furthermore, there were no saplings less than 2m in height even though Sasa was absent, although the gap ratio exceeded 50% in Mt. Takakuma.(3) The nut production vas large in 1998, however there were remarkably few viable nuts because the proportion of empty nuts was nearly 80%. Although the mortality of nuts in winter season was low, there were no current seedlings whether Sasa was removed or not in the autumn of the mast year.(4) The beech in Takakuma did not regenerate successfully, and other canopy tree species or the community of shrubs with Sasa may replace the beech stands.