Indirect assessment of seed dispersal effectiveness for Solanum riparium (Solanaceae) based on habitat use and rate of fruit disappearance

Abstract

(*)The ability of a plant’s propagule to reach microhabitats with the adequate conditions for seed germination and sapling establishment will have a direct effect on the plant’s fitness. In the case of fleshy- fruited plants, the seeds are dispersed by frugivorous animals. One part of the seed dispersal process is the removal of the fruits, which contain the seeds, from the parental plant. Another important part of the dispersal process is where the seeds land, especially for species with specific light, temperature or humidity needs for germination, such as disturbance colonizers. Solanum riparium (Solanaceae) is a shade intolerant species found in forest gaps within a subtropical montane forest and along river and road edges in North-western Argentina. In this study I assess the relative importance of bats and birds as seed dispersers of S. riparium (Solanaceae) in forest gaps and river edges, based on data on fruit disappearance during the night and during the day. I also classify seed dispersers according to the habitat types in which they were caught with mist-nets. Diurnal and nocturnal fruit disappearance rate did not differ and neither did disappearance rate between habitats. The results of this study suggest that, based on habitat use, the best seed dispersers for S. riparium are the frugivorous birds Atlapetes citrinellus and Turdus rufiventris, commonly caught at river edges and forest gaps. Based on habitat use of the frugivorous bats studied here, Sturnira lilium and S. erythromos, they potentially disperse half of the seeds to forest gaps and river edges, which are appropriate sites for germination of S. riparium seeds, and half to the river bank, a place with high risk of seeds being washed away and destroyed by occasionally strong water currents.

(*)Picture: Pedro Blendinger