Recruitment in Dentaria bulbifera; the roles of dispersal,habitat quality and mollusc herbivory

Abstract. We investigated the effects of dispersal limitation, diaspore density, soil chemistry, disturbance and mollusc herbivory on the abundance and distribution of the perennial forest herb Dentaria bulbifera (Brassicaceae). After experimental sowing of bulbils in originally empty patches, juveniles of Dentaria emerged in 83% of plots. The seventh year after sowing, plants still persisted and were reproducing in several plots, demonstrating that the species is dispersal‐limited. However, long‐term survival of transplants was higher at sites where Dentaria occurred naturally, and this difference increased with time after sowing. Thus, the importance of local factors may only be expressed fully several years after colonisation. Differences in soil chemistry and disturbance treatment were not associated with differences in patch suitability. Removal of molluscs, however, significantly increased recruitment, and the effects of a single molluscicide treatment persisted after four years. We conclude that dispersal is not the only limitation to the distribution of Dentaria, and that local factors, such as mollusc herbivory, are also crucial.