Oecologia

, Volume 139, Issue 1, pp 45–54 | Cite as

Effects of dung and seed size on secondary dispersal, seed predation, and seedling establishment of rain forest trees

Plant Animal Interactions

Abstract

Seeds dispersed by tropical, arboreal mammals are usually deposited singly and without dung or in clumps of fecal material. After dispersal through defecation by mammals, most seeds are secondarily dispersed by dung beetles or consumed by rodents. These post-dispersal, plant-animal interactions are likely to interact themselves, as seeds buried by dung beetles are less likely to be found by rodents than unburied seeds. In a series of three experiments with seeds of 15 species in central Amazonia (Brazil), we determined (1) how presence and amount of dung associated with seeds influences long-term seed fate and seedling establishment, (2) how deeply dung beetles bury seeds and how burial depth affects seedling establishment, and (3) how seed size affects the interaction between seeds, dung beetles, and rodents. Our overall goal was to understand how post-dispersal plant-animal interactions determine the link between primary seed dispersal and seedling establishment. On average, 43% of seeds surrounded by dung were buried by dung beetles, compared to 0% of seeds not surrounded by dung (n=2,156). Seeds in dung, however, tended to be more prone than bare seeds to predation by rodents. Of seeds in dung, probability of burial was negatively related to seed size and positively related to amount of dung. Burial of seeds decreased the probability of seed predation by rodents three-fold, and increased the probability of seedling establishment two-fold. Mean burial depth was 4 cm (0.5–20 cm) and was not related to seed size, contrary to previous studies. Probability of seedling establishment was negatively correlated with burial depth and not related to seed size at 5 or 10 cm depths. These results illustrate a complex web of interactions among dung beetles, rodents, and dispersed seeds. These interactions affect the probability of seedling establishment and are themselves strongly tied to how seeds are deposited by primary dispersers. More generally, our results emphasize the importance of looking beyond a single type of plant-animal interaction (e.g., seed dispersal or seed predation) to incorporate potential effects of interacting interactions.

Keywords

Central Amazonia Plant-animal interactions Rain forest Seed fate 

Notes

Acknowledgements

We thank R. Bodmer, J. Brockmann, C. Chapman, F. Putz, T. Theimer, and three anonymous reviewers for comments on the manuscript. Financial and logistic support were provided by the Department of Zoology and College of Liberal Arts and Sciences at the University of Florida, the Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia (INPA), Smithsonian Institution, Lincoln Park Zoo, and Wildlife Conservation Society. All experiments in this study comply with current Brazilian laws. This is contribution number 419 in the INPA-Smithsonian-BDFFP technical series.

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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  1. 1.Centro de Investigaciones en EcosistemasUniversidad Nacional Autónoma de MéxicoMoreliaMexico
  2. 2.Department of ZoologyUniversity of FloridaGainesvilleUSA

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