Responses of woody saplings mammalian herbivory in an exposed to chronic African savanna

Dario. A. Fornara, Johan T. Du Toit

    Research output: Contribution to journalArticle

    Abstract

    Suppressed growth forms of woody species are common where fire and herbivory are major ecosystem drivers, such as in African savannas. Nevertheless, despite their importance in maintaining plant population viability, woody plants in suppressed growth forms have received little attention in ecological studies. We measured a set of morpho-functional traits and investigated plant density variation in suppressed growth forms (hereafter we refer to them as saplings) of two common species, Acacia nigrescens and Acacia tortilis, across sites that had undergone very different histories of attack from large herbivores while fire had been absent for at least 13 y. We show that heavily browsed saplings have higher regrowth abilities, twice the number of stems produced by the main root crown and twice the root diameter at 5 cm soil depth, than lightly browsed saplings. This suggests that Acacia saplings are resilient to chronic herbivory and show high morphological plasticity. However, we show that mammalian herbivores can strongly limit sapling recruitment to mature size classes and possibly affect variation in sapling density between heavily and lightly browsed sites. Further studies should investigate whether the persistence of the sapling bank can be ascribed to the ``storage effect'' by which a plant's reproductive potential is ``stored'' in a suppressed growth form until a window of opportunity allows rapid maturity.
    LanguageEnglish
    Pages129-135
    JournalÉcoscience
    Volume15
    Issue number1
    Publication statusPublished - 2008

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    saplings
    savannas
    herbivores
    Acacia tortilis
    root crown
    Acacia
    woody plants
    plant density
    regrowth
    soil depth
    viability
    plant growth
    stems
    ecosystems

    Cite this

    Fornara, Dario. A. ; Du Toit, Johan T. / Responses of woody saplings mammalian herbivory in an exposed to chronic African savanna. In: Écoscience. 2008 ; Vol. 15, No. 1. pp. 129-135.
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    abstract = "Suppressed growth forms of woody species are common where fire and herbivory are major ecosystem drivers, such as in African savannas. Nevertheless, despite their importance in maintaining plant population viability, woody plants in suppressed growth forms have received little attention in ecological studies. We measured a set of morpho-functional traits and investigated plant density variation in suppressed growth forms (hereafter we refer to them as saplings) of two common species, Acacia nigrescens and Acacia tortilis, across sites that had undergone very different histories of attack from large herbivores while fire had been absent for at least 13 y. We show that heavily browsed saplings have higher regrowth abilities, twice the number of stems produced by the main root crown and twice the root diameter at 5 cm soil depth, than lightly browsed saplings. This suggests that Acacia saplings are resilient to chronic herbivory and show high morphological plasticity. However, we show that mammalian herbivores can strongly limit sapling recruitment to mature size classes and possibly affect variation in sapling density between heavily and lightly browsed sites. Further studies should investigate whether the persistence of the sapling bank can be ascribed to the ``storage effect'' by which a plant's reproductive potential is ``stored'' in a suppressed growth form until a window of opportunity allows rapid maturity.",
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    Fornara, DA & Du Toit, JT 2008, 'Responses of woody saplings mammalian herbivory in an exposed to chronic African savanna', Écoscience, vol. 15, no. 1, pp. 129-135.

    Responses of woody saplings mammalian herbivory in an exposed to chronic African savanna. / Fornara, Dario. A.; Du Toit, Johan T.

    In: Écoscience, Vol. 15, No. 1, 2008, p. 129-135.

    Research output: Contribution to journalArticle

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