Fluctuation in seed abundance has contrasting effects on the fate of seeds from two rapidly germinating tree species in an Asian tropical forest

The seed predator satiation hypothesis states that high seed abundance can satiate seed predators or seed dispersers, thus promoting seed survival. However, for rapidly germinating seeds in tropical forests, high seed abundance may limit dispersal as the seeds usually remain under parent trees for long periods, which may lead to high mortality due to rodent predation or fungal infestations. By tracking 2 species of rapidly germinating seeds (Pittosporopsis kerrii, family Icacinaceae; Camellia kissi, family Theaceae), which depend on dispersal by scatter-hoarding rodents, we investigated the effects of seed abundance at the community level on predation and seed dispersal in the tropical forest of Xishuangbanna Prefecture, Southwest China. We found that high seed abundance at the community level was associated with delayed and reduced seed removal, decreased dispersal distance and increased pre-dispersal seed survival for both plant species. High seed abundance was also associated with reduced seed caching of C. kissi, but it showed little effect on seed caching of P. kerrii. However, post-dispersal seed survival for the 2 plant species followed the reverse pattern. High seed abundance in the community was associated with higher post-dispersal survival of P. kerrii seeds, but with lower post-dispersal survival of C. kissi seeds. Our results suggest that different plant species derive benefit from fluctuations in seed production in different ways.