An ant-plant mesocosm experiment reveals dispersal patterns of myrmecochorous plants

Abstract

For Central European herbs, ants are one common dispersal vector acting at relatively small spatial scales. Though extensively studied concerning the dierent benefits to plants, specific dispersal patterns mediated by ants have been reportedly very sparsely and without any validation. Thus, we studied the seed dispersal pattern of a set of myrmecochorous plant species in a novel mesocosm experiment. We examined the seed dispersal distances of four forest herbs (Hollow Root-Corydalis cava (L.) Schweigg. & Korte, Alpine Squill-Scilla bifolia L., and Common Dog-violet-Viola riviniana Rchb. and the annual Ivy-leaved Speedwell-Veronica hederifolia L.) by the red ant Myrmica ruginodis Nylander in 8.25 m2 large plots under natural conditions with and without ants. In the presence of Myrmica ants, the bulb geophytes C. cava and S. bifolia showed a significantly higher fraction of dispersed seedlings and a maximum dispersal distance of 322 cm. Estimated by nearest neighbor analyses, distances between single C. cava seedlings were significantly higher in ant plots than in exclosures without ants. The annual species Veronica hederifolia showed a few dispersed seedlings in ant plots only, while the diplochorous hemicryptophyte Viola riviniana germinated in a widely scattered manner with distances up to 241 cm due to ballochorous dispersal in both ant and exclosure plots, but with a maximum of 324 cm only by means of ants. Our results indicate the escape from the mother plant and dispersal for distance as an important benefit for myrmecochorous species, potentially accompanied by benefits through reduced competition.