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Climatic warming strengthens a positive feedback between alpine shrubs and fire

Authors

  • James S. Camac,

    Corresponding author
    1. The Centre of Excellence for Environmental Decisions, School of BioSciences, The University of Melbourne, Parkville, Vic., Australia
    2. Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., Australia
    • Correspondence: James Camac, Centre of Excellence for Biosecurity Risk Analysis, School of BioSciences, The University of Melbourne, Melbourne, Vic. 3010, Australia, tel. +61 3 8344 0071, fax +61 3 9348 1620, e-mail: james.camac@gmail.com

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  • Richard J. Williams,

    1. Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., Australia
    2. Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
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  • Carl-Henrik Wahren,

    1. Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., Australia
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  • Ary A. Hoffmann,

    1. Research Centre for Applied Alpine Ecology, La Trobe University, Melbourne, Vic., Australia
    2. Bio21 Institute, School of BioSciences, The University of Melbourne, Melbourne, Vic., Australia
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  • Peter A. Vesk

    1. The Centre of Excellence for Environmental Decisions, School of BioSciences, The University of Melbourne, Parkville, Vic., Australia
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Abstract

Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold. Experimental warming also doubled growth rates of tall shrub seedlings and could potentially increase their survival. By contrast, warming had no effect on shrub recruitment, postfire tussock regeneration, or how tussock grass affected shrub seedling growth and survival. These findings indicate that warming, coupled with more frequent or severe fires, will likely result in an increase in the cover and abundance of evergreen shrubs. Given that shrubs are one of the most flammable components in alpine and tundra environments, warming is likely to strengthen an existing feedback between woody species abundance and fire in these ecosystems.

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