Epizoochorous seed dispersal in relation to seed availability – an experiment with a red fox dummy Hovstad, Knut Anders 1,2Ã ; Borvik, Silje 1,3 & Ohlson, Mikael 1,4 1 Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, PO Box 5003, NO-1432 A ˚ s, Norway 2 Norwegian Institute for Agriculture and Environmental Research, Grassland and Landscape Division, Kvithamar, NO-7500 Stjrdal, Norway; 3 E-mail silje.borvik@gmail.com; 4 E-mail mikael.ohlson@umb.no; Ã Corresponding author; E-mail knut.hovstad@bioforsk.no Abstract Questions: Is the red fox a potential vector for epizoochor- ous seed dispersal? Can seed attachment and retention be predicted from plant and seed traits? Location: Grasslands in southern Norway. Methods: Epizoochorous seed attachment on the red fox was studied by walking a dummy fox through the vegeta- tion and comparing seeds found on the dummy with the estimated seed availability in the vegetation. Seed reten- tion, i.e. the ability of different seeds to stay on the fox, was estimated in a separate experiment. Seed attachment and retention were related to plant and seed traits using statistical models that account for heteroscedasticity and zero-inflated data. Results: The majority of seeds attached to the fox origi- nated from a few species, but also species without specific seed traits that are supposed to enhance epizoochory attached at least some seeds to the fox. The probability of seed attachment was positively related to plant height, bristle and hooked seed appendages, and negatively re- lated to winged appendages, seed mass, and seed sphericity. Seed retention was positively related to the seed traits bristles, hooks and pappus. For several species, the results indicate a high potential for dispersal over long distances. Conclusions: In modern agricultural landscapes, large herbivores are often restricted in their mobility or are found at low densities, and other animal vectors may therefore be important for seed dispersal. In our study, a range of plant species were able to disperse by attaching seeds to, and having their seeds retained in, the fox fur some distance. We suggest that the red fox may be an important vector for epizoochorous seed dispersal in the agricultural landscape. Keywords: Dispersal vector; Epizoochory; Seed attachment; Seed retention; Seed traits; Vulpes vulpes. Nomenclature: Lid & Lid (1994). Abbreviation: AICc 5 Akaike’s Information Criterion cor- rected for small sample size; I seed 5 index representing the attachment potential of seeds; QAICc 5 AICc corrected for over-dispersion. Introduction Seed dispersal is a key process determining the population dynamics and spatial distribution of plants (Nathan & Muller-Landau 2000; Vandvik & Goldberg 2006). Although most seeds are dispersed over only a short distance from the mother plant (Harper 1977), dispersal over longer distances is important, as it provides plants with the opportu- nity to colonize new and distant habitats, and exchange genetic material between populations within metapopulations (Bohrer et al. 2005). Land- use changes have caused an extensive reduction and fragmentation of species-rich grasslands in Europe, and there is a growing body of evidence indicating that both the composition and diversity of grassland communities are limited by seed availability (Zobel et al. 2000; Vandvik & Goldberg 2006). Taken to- gether, this lends weight to the importance of seed dispersal to sustain plant diversity (Vandvik & Goldberg 2006; Zobel et al. 2006). Epizoochorous dispersal, i.e. dispersal of seeds on the exterior of animals, is an important mechan- ism for dispersal over intermediate and long distances and most likely plays a larger role in me- tapopulation dynamics than in the spatial distribution of seeds at a small scale (Nathan & Muller-Landau 2000; Higgins et al. 2003; Adriaens et al. 2007). There are two crucial steps in epi- zoochorous dispersal; first, the seed has to come in Journal of Vegetation Science 20: 455–464, 2009 & 2009 International Association for Vegetation Science