XVI International Botanical Congess

We examined the effects of local plant abundance on the pollinator behaviour and plant reproductive success in artificial populations of different sizes and densities. Visitation rate of bumblebees was higher in large and sparse populations. Size and density treatments probably affected in the same direction, enlarging the habitat area and making the patch more visible to pollinators. At low plant density the bumblebees probed more flowers per plant than at higher density. Total seed yield was higher in sparse populations, which can be due to both pollination success and resource competition. For self-compatible L. viscaria resource availability may be a more important factor in determining the reproductive success, while self-incompatible plants are probably more sensitive to changes in pollinator abundance.