Dispersal distance and achene quality of the rare anemochorous species Arnica montana L.: implications for conservation

In The Netherlands, Arnica montana (Asteraceae) is a rare plant species. Future survival in The Netherlands depends on its ability to disperse between source populations and habitats, newly created by man. Plumed Asteraceae achenes are often considered to disperse over large distances. Therefore, these species are expected to establish easily during vegetation restoration. In this paper, the flying capability of plumed achenes is investigated in a wind-tunnel experiment. An effort is made to establish the correlation between seed quality and flying ability. It was shown that A. montana achenes are inefficient dispersers. Pappus size is significantly, but weakly, positively correlated with achene mass. Heavier achenes, therefore, stay closer to the point of release than lighter ones. There was a positive correlation between achene weight and both germination and seedling quality. Consequently, germination and seedling quality declined considerably with increasing flying capability of the achenes. It seems that A. montana, despite its plumed achenes, is adapted to an environment where moderate dispersal distances are required, up to several metres. Only lowquality achenes reach larger distances. Since large distance dispersal is a prerequisite of establishment of new populations, establishment of this species on isolated sites the Dutch landscape will depend on transport by human activity.