LAUSR

Premise The synchronous highly variable flower or seed production among years within a population- i.e., masting - has been reported in numerous perennial plants. Although ecological advantages of masting are recognized as the enhancement of pollination efficiency and/or escape from predator attack, little is known about the degree of these advantages and the variation in masting behavior among populations of conspecific plants. Methods We observed flowering ramet density and reproductive success (fruit-set success and herbivorous damage) of a perennial herb, Veratrum album subsp. oxysepalum, across six lowland and six alpine populations in northern Japan during 2-3 years. We then analyzed the relationship between floral density and reproductive success to clarify the ecological significance of mast flowering. Furthermore, flowering intervals of individual plants were estimated by counting annual scars on rhizomes. Results Mast flowering was observed in the most populations, but flowering intervals of individual plants were shorter in the alpine populations compared with the lowland populations. Floral damage by stem borers (dipteran larvae) and seed predation by lepidopteran larvae were intense in the lowland populations. The seed production of individual ramets increased with higher floral density owing to the effective avoidance of floral-stem damage and seed predation. Although stem borers were absent in alpine habitat, seed predation decreased with higher floral density also in the alpine populations. Pollination success was independent of floral density in both of the alpine and lowland populations. Conclusions These results strongly support the predator satiation hypothesis for the mast flowering behavior in this species. This article is protected by copyright. All rights reserved.