Strict mast fruiting for a tropical dipterocarp tree: a demographic cost–benefit analysis of delayed reproduction and seed predation

Authors

  • Marco D. Visser,

    Corresponding author
    1. Van Hall Larenstein, Wageningen University and Research Centre, Larensteinselaan 26a, 6880 GB Velp, The Netherlands
    2. Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
      Correspondence author. E-mail: m.visser@science.ru.nl
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  • Eelke Jongejans,

    1. Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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  • Michiel van Breugel,

    1. Van Hall Larenstein, Wageningen University and Research Centre, Larensteinselaan 26a, 6880 GB Velp, The Netherlands
    2. Centre for Tropical Forest Science, Smithsonian Tropical Research Institute, Av. Roosevelt 401, Balboa, Ancón, Panamá, Republic of Panamá
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  • Pieter A. Zuidema,

    1. Institute of Environmental Biology, Ecology and Biodiversity, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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  • Yu-Yun Chen,

    1. Department of Natural Resources and Environmental Studies, National Donghwa University, Hualien, 974 Taiwan
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  • Abdul Rahman Kassim,

    1. Natural Forest Division, Forest Research Institute Malaysia, Kepong, Kuala Lumpur, Malaysia
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  • Hans de Kroon

    1. Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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  • Present address: Forest Ecology and Management, Centre for Ecosystem Studies, Wageningen University, Box 47, 6700 AA Wageningen, The Netherlands.

Correspondence author. E-mail: m.visser@science.ru.nl

Summary

1. Masting, the production of large seed crops at intervals of several years, is a reproductive adaptation displayed by many tree species. The predator satiation hypothesis predicts that starvation of seed predators between mast years and satiation during mast years decreases seed predation and thus enhances tree regeneration.

2. Mast fruiting comes at demographic costs such as missed reproduction opportunities and increased density-dependence of recruits, but it remains unknown if predator satiation constitutes a sufficiently large benefit for masting to evolve as a viable life-history strategy. So far, no studies have quantified the net fitness consequences of masting.

3. Using a long-term demographic data set of the dipterocarp Shorea leprosula in a Malaysian forest, we constructed stochastic matrix population models and performed a demographic cost–benefit analysis.

4. For observed values of mast frequency and seed predation rates, we show that strict masting strongly increases fitness compared with fruiting annually. Model results also show that the demographic costs of mast fruiting are very low compared to the demographic losses due to seed predation in a scenario of annual fruiting. Finally, we find that mast fruiting would still be selected for even at low levels of seed predation and when including additional costs such as decreased adult growth rates, limiting crop size and density-dependent seedling survival.

5.Synthesis. Our results are consistent with the predictions of the predator satiation hypothesis: mast fruiting increases fitness for a range of seed predation levels. Under seed predation pressure annually fruiting species are at a strong disadvantage and as a result a mast fruiting strategy may swiftly confer a fitness advantage. Our study shows that demographic modelling allows the weighing of fitness benefits and costs of life-history phenomena such as strict masting.

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