Abstract
We investigated the effects of variation in seed density on small-rodent predation of Araucaria angustifolia seeds. Seed removal experiments were conducted simultaneously in two contrasting stands (seed-poor – planted with the slash pine Pinus elliottii and seed-rich – planted with A. angustifolia) outside the seed production period and also during the seed production period. Predator abundance (evaluated through live-trapping) did not vary significantly between stands. Tracking of thread-marked seeds indicated that rodents frequently move seeds away from the source point and that seed-carrying distance (range 3.91–8.30 m) is not significantly related to area or season. Seed removal rates were high in both areas outside the seed production period but during seed-producing months they were significantly lower in the seed-rich area, supporting the predator-satiation hypothesis. The A. angustifolia strategy of synchronous production of large seed crops but with high between-year variation is potentially successful at limiting the impacts of rodent predators.
Acknowledgements
We thank the Brazilian Federal Environment Agency (IBAMA) for authorizing our fieldwork in the SFPNF. This study was supported by the Fundação O Boticário de Proteção a Natureza (process # 0679/20022) and UNISINOS. While conducting this research work E.M.V. received a personal research grant (306347/2004-0) and J.F.R. received an undergraduate scholarship (501907/2004-1) from the Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil (CNPq). Two anonymous reviewers provided useful comments on an earlier version of the paper.