Central Die-back of Monoclonal Stands ofReynoutria japonicain an Early Stage of Primary Succession on Mount Fuji

摘要: Reynoutria japonicais a common perennial pioneer species on Japanese volcanoes. In volcanic desert (1500m above sea level) Mount Fuji (3776m), central Japan, this forms circular stands (patches). As patch develops, shoot density decreases in its centre (‘central die-back’). The die-back has been considered key process the early stages of primary succession, though mechanism unknown. The pattern development, population dynamics aerial shoots, and growth patterns below-ground organs were analysed order to investigate die-back, following traits are clarified: (1) areas occur most small patches (approx. 1m2) without later successional species; (2) characteristics dependent both their position within size; (3) despite large differences density, neither time course nor mortality differs between periphery patches; (4) rhizomes ofR. japonicagrow outwards with regular sympodial branching. From these results, it is concluded that interspecific intraspecific competition likely be cause phenomenon, but brought about intrinsically by rhizome systems. We also discuss importance facilitating establishment succession.