Seed fall and phenological overlap in a guild of ant-dispersed herbs.

The timing of seed fall was studied in a guild of seven ant-dispersed forest herbs in NE-Zealand, Denmark. It is demonstrated, that the seed fall curves of Carex pilulifera, Melica uniflora and Luzula multiflora are remarkably different, representing logistic, hyperbolic, and linear relationships, respectively. The influence of environmental factors, and the significance to dispersal and predation, is discussed. It is suggested, that the three types of curves represent different strategies of seed fall. Simple, and explanded models of seed fall rate indicate that the density of seeds available to ants was more than 20 times greater for C. pilulifera than for M. uniflora. The observed phenological overlap of dispersal periods in the guild conformed to random expectations. Thus, the competition hypothesis was rejected, as there were no indications of a shift in phenology resulting from interspecific competition for the dispersal vector.