Resources determine frugivore assemblages and fruit removal along an elevational gradient

• Is the interplay among habitat, frugivores and plants affected by climatic conditions?
• Increasing local resources enhanced the number of frugivores and fruit removal.
• Differences in resource importance along the elevational gradient.
• Climatic conditions indirectly affect fruit removal through changes in resources.

Geographic variation in the diversity, abundance or composition of plant and frugivore assemblages may have consequences for seed dispersal processes. Such variations may be related to climatic conditions as well as habitat characteristics such as fruit availability and forest complexity. Studying frugivore assemblages and seed dispersal processes along an elevational gradient can help to elucidate the interplay between the extent of dispersal services provided by frugivores and the geographic variability of the food resources. We studied frugivore assemblages on and fruit removal from 28 rowan trees (Sorbus aucuparia) along an elevational gradient in the Bavarian Forest, Germany. Both, the number of frugivore species and the number of frugivore individuals were significantly enhanced by high fruit availability. In both cases we found a slight interaction between elevation and fruit availability indicating a higher attractiveness of fruits for frugivores at lower than at higher elevations. A high number of frugivore individuals in turn significantly increased fruit removal from rowan trees. Here, we found a significant interaction between elevation and the number of frugivore individuals suggesting that the number of frugivores is of major importance for fruit removal particularly at lower elevations. Path analysis corroborated that the number of frugivore individuals indirectly mediated the effect of fruit availability on fruit removal. These findings suggest that fruit removal is rather influenced by changes in habitat characteristics than in climatic conditions across space.