Epizoochorous and post-dispersal processes in a rare plant species: Jurinea cyanoides (L.) Rchb. (Asteraceae)

It could be shown that establishment of J. cyanoides is possible after sheep-epizoochorous dispersal, but is severely limited by several factors. First, retention time is mostly short (only 18% of the diaspores remained in the fleeces >2 h). Thus, the seed shadow is concentrated around the place of attachment (mostly <5 m distance, maximum 17 m). Second, seedling emergence of dispersed achenes is severely limited by above-ground granivory (99%). Third, establishment is limited by seedling mortality (68%) due to summer drought. The seedlings germinated from achenes that had been incorporated into the soil (or into deeper parts of the bryophyte layer). The second experiment showed that sheep trampling significantly enhanced the incorporation of achenes into the soil compared with controls. Our study gives evidence that sheep can play a dual role: diaspore transport and facilitation of establishment by trampling.