PHENOLOGY, GROWTH AND ECOPHYSIOLOGICAL CHARACTERISTICS OF FALLOPIA-SACHALINENSIS

Fallopia (Polygonum) sachalinensis (Polygonaceae) is native to the Far East from where it was introduced into Europe and Northern America. I t has only recently appeared on the large alluvial plains of alpine ri vers, while it has formed monospecific stands in many habitats. In thi s study, we investigated some of the biological characteristics of thi s species in order to predict its invasiveness under the specific envi ronmental conditions of alpine alluvia. When compared to other plants which tend to monopolize space, F. sachalinensis appears to have a lif e cycle characterized by an early seasonal development. It exhibits a high growth rate - ca. 4 to 5 cm/day, and its productivity is associat ed with intrinsic characteristics of the species: abundant leaf cover, the appearance of branches when the leaves reach an optimal size on t he main stem, and favourable leaf orientation to capture high light in tensity. Another morphological characteristic is the presence of a lar ge medullary air cell containing a liquid rich in mineral salts which can be used by the plant when the demand for evaporation increases. Cl onal spread associated with an extraordinarily high rate of proliferat ion of below-ground organs, and mechanisms for adaptation to adverse c onditions are biological traits rendering F. sachalinensis an invader in alluvial plains along alpine rivers. There is a risk that such spec ies experience a demographic explosion in the geographical region unde r study.