Architecture and development in Fagus japónica - Fagus crenata forest near Mount Takahara,Japan

Abstract. The architecture and development of forest eco-units in a mixed Japanese beech forest were studied by means of aerial photographs and belt-transects. Fagus japónica dominates in this forest because it has the ability to reproduce through root-collar sprouts. Each individual has a number of stems that reach the canopy. Two eco-unit types are recognized. Most abundant is the type dominated by multiple-stem F. japónica individuals (type A). The other type is dominated by other tall tree species, mostly Fagus crenata (type B). The most common cycle of development for type A is mature / stem-breakage / growing / mature. After stem-breakage, suppressed sprouts of the same individual replace the broken stem by growing quickly into the canopy. This accounts for the low coverage of patches in the early growing phases and the high coverage in mature phases in the aerial photographs. After uprooting off. japónica or after death of other canopy tree species, a seedling phase will be necessary, during which canopy species establish themselves from seed and F. japónica may establish itself from sprouts. Dwarf bamboo appeared to inhibit the establishment of seedlings but it does not affect the establishment of F. japónica sprouts. It is concluded that the dominance of F. japónica over other tall tree species is the result of F. japónica reproducing by sprouts.