IMPLICATION TO THE SPATIO-TEMPORAL GENETIC STRUCTURE FOR MULTI-STEMMED CLUMPS OF FAGUS JAPONICA STAND, CENTRAL HONSHU, JAPAN

Fagus japonica is an endemic multi-stemmed canopy tree species, which is distributed Pacific side of central Honshu. This multi-stemmed unique growth form can be considered as a vegetative propagation by sprouting. It supposed to be that when a single genet established at a certain position, the clump would maintain longer period of time than each stem； when one stem was dead or fallen, another mature stem of the same genet can survive and keep the genet. However, it is not clear that this growth form contributes to the genetic structure for next generation. We use allozyme as a gene marker and clarify the contribution of multi-stemmed individual clump of F. japonica. By counting tree rings, each stem of F. japonica survives ca. 160 years. A mature size of F. japonica is known to be 60cm in circumference, and this size is ca. 100 years. It means that one stem of F. japonica contributes to sexual mating for about 60 years. Fagus japonica also has a mast-fruiting, like other Fagus species. It is important for a genet to remain where once established within a population, and contribute sexual mating in mast-fruiting year to inherent its genes. A mature clump had more than three mature stems. This is advantageous when one stem fell by forest disturbance, however, another stems can supplement its gap. The genetic parameter also showed that the differentiation of genetic variation was less than other Fagus species, which do not vegetatively propagate.