The legacy of mid-Holocene fire on a Tasmanian montane landscape

Authors

  • Michael-Shawn Fletcher,

    Corresponding author
    1. Department of Resource Management and Geography, University of Melbourne, Parkville, VIC, Australia
    2. Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australia
    3. Institute of Ecology and Biodiversity, University of Chile, Santiago, Chile
    • Correspondence: Michael-Shawn Fletcher, Department of Resource Management and Geography, University of Melbourne, Parkville, VIC 3010, Australia.

      E-mail: msfl@unimelb.edu.au

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  • Brent B. Wolfe,

    1. Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON, Canada
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  • Cathy Whitlock,

    1. Institute on Ecosystems, Montana State University, Bozeman, MT, USA
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  • David P. Pompeani,

    1. Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA, USA
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  • Hendrik Heijnis,

    1. Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Kirrawee, DC NSW, Australia
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  • Simon G. Haberle,

    1. Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australia
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  • Patricia S. Gadd,

    1. Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Kirrawee, DC NSW, Australia
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  • David M. J. S. Bowman

    1. School of Plant Science, University of Tasmania, Hobart, TAS, Australia
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Abstract

Aim

To assess the long-term impacts of landscape fire on a mosaic of pyrophobic and pyrogenic woody montane vegetation.

Location

South-west Tasmania, Australia.

Methods

We undertook a high-resolution multiproxy palaeoecological analysis of sediments deposited in Lake Osborne (Hartz Mountains National Park, southern Tasmania), employing analyses of pollen, macroscopic and microscopic charcoal, organic and inorganic geochemistry and magnetic susceptibility.

Results

Sequential fires within the study catchment over the past 6500 years have resulted in the reduction of pyrophobic rain forest taxa and the establishment of pyrogenic Eucalyptus-dominated vegetation. The vegetation change was accompanied by soil erosion and nutrient losses. The rate of post-fire recovery of widespread rain forest taxa (Nothofagus cunninghamii and Eucryphia spp.) conforms to ecological models, as does the local extinction of fire-sensitive rain forest taxa (Nothofagus gunnii and Cupressaceae) following successive fires.

Main conclusions

The sedimentary analyses indicate that recurrent fires over several centuries caused a catchment-wide transition from pyrophobic rain forest to pyrophytic eucalypt-dominated vegetation. The fires within the lake catchment during the 6500-year long record appear to coincide with high-frequency El Niño events in the equatorial Pacific Ocean, signalling a potential threat to these highly endemic rain forests if El Niño intensity amplifies as predicted under future climate scenarios.

Ancillary