Habitat complexity and invasive species: The impacts of gamba grass (Andropogon gayanus) on invertebrates in an Australian tropical savanna

Catherine Parr, Ben Ryan, Samantha Setterfield

    Research output: Contribution to journalArticle

    Abstract

    Habitat complexity is an important factor structuring local faunal assemblages. Many invasive plant species alter vegetation complexity because they are both functionally and structurally different from native flora. This study investigated the effects of an invasive grass (Andropogon gayanus Kunth.), which is invading undisturbed savannas in northern Australia. Although A. gayanus is a similar lifeform to that dominant in the native understory (i.e., a C4 grass), it is structurally different and significantly alters habitat complexity. We, therefore, hypothesized that there would be a substantial effect of the invasive grass on ant, spider, and other invertebrate assemblages. Contrary to our hypothesis, there was no effect of A. gayanus on ant species richness, abundance, or composition, nor were spiders or other invertebrates affected. Instead the change in weather conditions with season was more important in structuring the local invertebrate assemblages. Change in habitat complexity was most pronounced vertically, rather than horizontally at ground level, thus although there was a clear difference in the vertical structure between invaded and noninvaded habitats, the limited invertebrate response to different A. gayanus densities suggests some invertebrates are less sensitive to vertical changes in vegetation structure.
    Original languageEnglish
    Pages (from-to)688-696
    Number of pages9
    JournalBiotropica
    Volume42
    Issue number6
    DOIs
    Publication statusPublished - Nov 2010

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