Herbivory, growth rates, and habitat specialization in tropical tree lineages: implications for Amazonian beta-diversity

Authors

  • Greg P. A. Lamarre,

    1. Université Antilles Guyane, UMR Ecologie des Forêts de Guyane, 97310, Kourou, French Guiana
    2. INRA, UMR Ecologie des Forêts de Guyane, 97310, Kourou, French Guiana
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  • Christopher Baraloto,

    1. INRA, UMR Ecologie des Forêts de Guyane, 97310, Kourou, French Guiana
    2. Department of Biology, University of Florida, Gainesville, Florida 32611 USA
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  • Claire Fortunel,

    1. INRA, UMR Ecologie des Forêts de Guyane, 97310, Kourou, French Guiana
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  • Nallarett Dávila,

    1. Botany Graduate Program, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil
    2. Department of Integrative Biology, 1005 Valley Life Sciences Building Number 3140, University of California, Berkeley, California 94720 USA
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  • Italo Mesones,

    1. Department of Integrative Biology, 1005 Valley Life Sciences Building Number 3140, University of California, Berkeley, California 94720 USA
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  • Julio Grandez Rios,

    1. Department of Integrative Biology, 1005 Valley Life Sciences Building Number 3140, University of California, Berkeley, California 94720 USA
    2. Departamento de Biología, Universidad de la Amazonía Peruana, Iquitos, Peru
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  • Marcos Ríos,

    1. Departamento de Biología, Universidad de la Amazonía Peruana, Iquitos, Peru
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  • Elvis Valderrama,

    1. Departamento de Biología, Universidad de la Amazonía Peruana, Iquitos, Peru
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  • Magno Vásquez Pilco,

    1. Department of Integrative Biology, 1005 Valley Life Sciences Building Number 3140, University of California, Berkeley, California 94720 USA
    2. Departamento Forestal, Universidad de la Amazonía Peruana, Iquitos, Peru
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  • Paul V. A. Fine

    Corresponding author
    1. Department of Integrative Biology, 1005 Valley Life Sciences Building Number 3140, University of California, Berkeley, California 94720 USA
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  • Corresponding Editor: J. Cavender-Bares. For reprints of this Special Issue, see footnote 1, p. S1.

Abstract

Tropical plant diversity is extraordinarily high at both local and regional scales. Many studies have demonstrated that natural enemies maintain local diversity via negative density dependence, but we know little about how natural enemies influence beta-diversity across habitats and/or regions. One way herbivores could influence plant beta-diversity is by driving allocation trade-offs that promote habitat specialization across resource gradients. We therefore predicted that increasing resource availability should be accompanied by increasing herbivory rates and decreasing plant allocation to defense. Second, relative abundances within plant lineages are predicted to reflect patterns of habitat specialization and allocation trade-offs. A phylogenetic context is vital not only to compare homologous plant traits (including defense strategies) across habitat types, but also to connect evolutionary trade-offs to patterns of species diversification in each phylogenetic lineage.

We tested these predictions for trees in white-sand, clay terra firme, and seasonally flooded forests in Peru and French Guiana that represent the range of soil fertility, forest structure, and floristic compositions found throughout the Amazon region. We established 74 0.5-ha plots in these habitats and sampled all trees. Within 12 representative plots we marked newly expanding leaves of 394 saplings representing 68 species, including the most abundant species in each plot in addition to species from five focal lineages: Swartzia and Inga (Fabaceae), Protieae (Burseracaeae), Bombacoideae (Malvaceae), and Micropholis (Sapotaceae). We measured total leaf production rates for each sapling and calculated relative herbivory impact as the ratio between herbivory rate and leaf production rate.

Herbivory rates averaged 2.1% per month, did not correlate with leaf production rate, and were similar across habitats. Relative herbivore impacts exceeded leaf production rates for most species. Leaf production rate averaged 2.8%, was significantly higher in seasonally flooded forests than the other two habitats, and exhibited significant correlations with specific leaf area. Species with high herbivory rates exhibited significantly lower relative abundances in terra firme forests. Overall, focal species within lineages present contrasting patterns regarding their herbivory rates and leaf production rate within habitats. These results highlight why a lineage-based approach is necessary when attempting to connect hypotheses regarding evolutionary trade-offs to community assembly patterns.

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