Low resource availability limits weed invasion of tropical savannas

Harley R. Taylor, Ian J. Radford, Charles Price, Pauline Grierson

    Research output: Contribution to journalArticlepeer-review

    9 Citations (Scopus)

    Abstract

    The savanna biome is one of the least invaded among global biomes, although the mechanisms underpinning its resistance to alien species relative to other biomes is not well understood. Invaders generally are at the resource acquisitive end of functional global plant trait variation and in low-resource savanna environments we might expect that successful invaders will only outperform native species under resource rich or highly disturbed conditions. However, invaders may also directly exploit resource stressed environments using resource conservative traits in some situations. It’s also possible that successful invaders and native species largely overlap in their trait profiles indicating site specific environmental factors are responsible for invader success in particular contexts rather than a general trait and functional divergence between invaders and native species. To address these various hypotheses, we compared a suite of morphological and physiological traits in graminoid and herbaceous native and co-occurring invasive plant species across a range of habitats in savannas of the Kimberley region of northern Australia. Invader grass species had traits associated with resource acquisition and fast growth rates, such as high SLA and leaf nutrient contents. In contrast, dominant native perennial grasses had traits characteristic of resource conservation and slow growth in resource stressed conditions. Trait profiles among invasive forbs and legumes exhibited stress tolerant traits relative to their native counterparts. Invaders also displayed strong divergence in reproductive traits, suggesting diverse responses to disturbance not indicated by leaf economic traits alone. These results suggest that savannas may be resistant to invaders with resource acquisitive traits due to their strong resource limitation.

    Original languageEnglish
    Pages (from-to)861-875
    Number of pages15
    JournalBiological Invasions
    Volume20
    Issue number4
    Early online date13 Oct 2017
    DOIs
    Publication statusPublished - 1 Apr 2018

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