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SUMMARY Seeds of three plant species, Agrimonia eupatoria L., Geum rivale L. and Triglochin palustre L., were tested for their ability to remain attached in fur of fallow deer and domestic cattle under natural conditions in the field. The plant species are relatively common in managed semi‐natural pastures and all three species possess seed structures which enhance adhesive dispersal. The results indicate that seed morphology and the position of seeds on an animal's body influence the length of time that seeds are attached in fur. The relative adhesive seed dispersal ability of the plants (A. eupatoria> G. rivale> T. palustre) did not differ between the two investigated animal species. However, taking grooming behaviour into account, animal species may differ in dispersal efficiency. Seed morphological structures that increase the inherent capacity of adhesive dispersal may also be irritating to animals and initiate grooming. Potential dispersal distances were obtained for seeds on cattle, suggesting that adhesive seeds may disperse from tens of metres to a kilometre. The implications of the results of this study for plant dispersal in a fragmented landscape are discussed.

This study on epizoochory offers experimental data on retention times and potential dispersal distances of propagules of 13 plant species that commonly inhabit cultivated areas in the south of Sweden. Wood mouse Apodemus flavicollis was used as dispersal vector. Seven of the investigated species produce fruits that carry obvious hooks, barbs or bristles and for comparison the remaining six species, lacking such features, were also included. Excised fruits that initially carried appendages were used in a complementary comparison. Propagules were applied by hand to the back of the animals, which were which released in enclosures to move about freely. Observations were made continually until the seeds were dropped. The distance covered by the animals while moving was measured and the potential dispersal distances calculated. Small fruits were in general found to be more efficiently transported than large ones, but large propagules carrying appendages sometimes remained in place for considerable periods. The potential dispersal distances ranged up to nearly 30 m. The retention time was significantly enhanced by the presence of dispersal attributes. The behavioural pattern of the animals (grooming, movements) plays a significant part in the successful transportation of propagules. By comparing the result with similar experiments using fallow deer Dama dama and domestic cattle Bos taurus as dispersal vectors it can be stated that mice are surprisingly effective as seed dispersers. Large mammals disperse propagules on a larger scale (<1 km) compared with small mammals, that affect plant distribution more locally (<100 m). We consider adhesive dispersal a most significant component in plant metapopulation dynamics, considerably enhancing the probability of occasional propagules reaching suitable sites in a fragmented landscape.

Abstract. One of the most dramatic landscape changes during the 20th century in Sweden, like in most of Europe, has been the reduction and fragmentation of semi‐natural grasslands. Using a set of remnant semi‐natural grasslands, chosen to be as similar as possible, but differing in size, we have examined whether size of remnant fragments of traditionally managed semi‐natural grasslands in Sweden is related to patterns of species richness and composition. We focused on edge‐to‐interior relationships, since we expected that a possible impact from invasive habitat generalists would be manifested in a gradient from the edge of fragments to their interior. We found no relationship between size of grassland fragments and (a) overall species richness, (b) species richness at different spatial scales, and (c) abundance of some typical invader species or species characteristic of semi‐natural grasslands. However, the results indicated that larger grasslands have a comparatively larger number of species in the edges, whereas the opposite pattern was found in smaller grasslands. The similarity in species composition between the edge and the interior of the pastures also increased with grassland size. Thus, even though the overall species richness is still unaffected by reduction in grassland fragment size, the edges of smaller grasslands show signs of degradation, i.e. reduction in species richness and a decreased similarity to the grassland interior. We suggest that these kinds of effects may be early signs of fragmentation effects that in the future will result in species loss even if the present distribution of semi‐natural grasslands is maintained.

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