The high degree of isolation of forest “islands” relative to “continental” forested areas creates a naturally fragmented landscape in the savanna ecosystem. Because fragmentation can affect the intensity and quality of biological interactions (e.g., seed dispersal) we examined the abundance and species richness of seed rain produced by birds and bats in three different parts of forest islands (center, edge, and exterior) located at the Estación Biológica del Beni, Bolivia. Despite the fact that we found higher species density of seeds in the seed rain at the center of forest islands, when comparing species richness corrected for observed differences in density, species richness was higher at the edge of islands. The three parts of the islands did not differ in total number of seeds. Three genera (Byrsonima, Ficus, and Piper) contributed the most seeds to the seed rain. We found differences in the abundance of dispersed seeds probably because of the variation related with the disturbance line, where the savanna matrix interacts with the forest islands. Carollia perspicillata, Carollia brevicauda, and Sturnira lilium were the bats that contributed most to seed dispersal within forest islands, and Schistochlamys melanopis and Tyranneutes stolzmanni were the most important birds. The movement of seeds produced by bats and birds within forest islands of the savanna is crucial to assure the continuity of ecological process and dynamics of these forest islands.

El tamaño de las semillas de Vismia glaziovii Ruhl. (Guttiferae) y suVismia glaziovii Ruhl. (Guttiferae) y su Vismia glaziovii relación con la velocidad de germinación y tamaño de la plántula ResumenEn el presente trabajo analicé la variabilidad intraespecifi ca del tamaño de las semillas de Vismia glaziovii Ruhl y su posible efecto sobre la velocidad de germinación y el tamaño de las plántulas. glaziovii Ruhl y su posible efecto sobre la velocidad de germinación y el tamaño de las plántulas. glaziovii Los resultados muestran que el tamaño de las semillas no varía signifi cativamente entre árboles de las que provenian, pero la variación del tamaño de semilla entre los frutos de cada árbol sí es signifi cativa. También, el tamaño de la semilla no infl uye sobre la velocidad de germinación ni sobre el tamaño de las plántulas. Sugerimos que la variabilidad en tamaño no sea sufi ciente como para indicar diferencias en la cantidad de recurso almacenado. Este estudio permitirá contribuir al conocimiento de algunos aspectos de la dinámica de semillas y la regeneración de esta especie.Palabras clave: Vismia glaziovii, tamaño de semillas, germinación, tamaño de plántulas, bosque montano, Bolivia. AbstractIn the present work I analyzed the variability of the seeds size of Vismia glaziovii Ruhl. and its Vismia glaziovii Ruhl. and its Vismia glaziovii possible effect on germination speed and its seedling size. The results show that the size of the seeds does not vary signifi cantly between trees from which they came; but the variation as large as seed between the fruits of each tree is signifi cant. Also, the size of the seed does not infl uence the speed of germination nor the seedling size. We suggested that variability in size is not suffi cient as indicator of differences in the amount of stored resource. This study will allow contributing to the knowledge of some aspects of the dynamics of seeds and the regeneration of this species.