Past fire severity and intensity identified in SE Australian sediments using boron isotopes and FTIR spectroscopy
Past fire severity and intensity identified in SE Australian sediments using boron isotopes and FTIR spectroscopy
Landscape-scale bushfires threaten lives, property, and biodiversity. Understanding how their characteristics have changed over time proves vital in improving management strategies and understanding future ecosystem responses. Therefore, there is an urgent need to develop novel proxies to extend our existing record of past fire characteristics, such as severity and intensity. Here, we use carbon and nitrogen contents, Fourier Transform Infrared (FTIR) spectroscopy, and boron isotopes in a sedimentary archive to investigate past fire events in Namadgi National Park (southeastern Australia) and estimate their characteristics such as fire intensity and severity. Strontium and neodymium isotopes were used to assess the possible catchment-scale erosion events following fire. The aromatic/aliphatic ratio of sediments showed that fire frequency and intensity have increased in the last 200 years compared to the previous 3000. Boron isotopes were influenced by both lithology and fire severity, where negative excursions may result from higher contributions of bark to mineral ash, whilst positive excursions in the isotope ratio result from higher contributions of leaves. Negative excursions in the B isotope ratio, coinciding with positive excursions in the aromatic/aliphatic ratio, were hypothesised to record low-severity fires that experienced longer residence times. This multi-proxy approach provides valuable insights into past fire characteristics. By improving our understanding of how fire characteristics have changed in the past, the results can inform mechanistic models to improve predictions of fire severity and intensity changes in the future.
Fire, Fire intensity, FTIR spectroscopy, Isotopes, Southeastern Australia
Ryan, Rebecca
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Lu, Shawn
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Lemarchand, Damien
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Thomas, Zoë
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Simkovic, Ivan
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Dlapa, Pavel
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Worthy, Martin
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Wasson, Robert
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Bradstock, Ross
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Haynes, Katharine
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Dosseto, Anthony
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1 September 2025
Ryan, Rebecca
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Lu, Shawn
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Lemarchand, Damien
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Thomas, Zoë
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Simkovic, Ivan
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Dlapa, Pavel
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Worthy, Martin
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Wasson, Robert
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Bradstock, Ross
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Haynes, Katharine
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Dosseto, Anthony
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Ryan, Rebecca, Lu, Shawn, Lemarchand, Damien, Thomas, Zoë, Simkovic, Ivan, Dlapa, Pavel, Worthy, Martin, Wasson, Robert, Bradstock, Ross, Haynes, Katharine and Dosseto, Anthony
(2025)
Past fire severity and intensity identified in SE Australian sediments using boron isotopes and FTIR spectroscopy.
Quaternary Science Reviews, 369, [109605].
(doi:10.1016/j.quascirev.2025.109605).
Abstract
Landscape-scale bushfires threaten lives, property, and biodiversity. Understanding how their characteristics have changed over time proves vital in improving management strategies and understanding future ecosystem responses. Therefore, there is an urgent need to develop novel proxies to extend our existing record of past fire characteristics, such as severity and intensity. Here, we use carbon and nitrogen contents, Fourier Transform Infrared (FTIR) spectroscopy, and boron isotopes in a sedimentary archive to investigate past fire events in Namadgi National Park (southeastern Australia) and estimate their characteristics such as fire intensity and severity. Strontium and neodymium isotopes were used to assess the possible catchment-scale erosion events following fire. The aromatic/aliphatic ratio of sediments showed that fire frequency and intensity have increased in the last 200 years compared to the previous 3000. Boron isotopes were influenced by both lithology and fire severity, where negative excursions may result from higher contributions of bark to mineral ash, whilst positive excursions in the isotope ratio result from higher contributions of leaves. Negative excursions in the B isotope ratio, coinciding with positive excursions in the aromatic/aliphatic ratio, were hypothesised to record low-severity fires that experienced longer residence times. This multi-proxy approach provides valuable insights into past fire characteristics. By improving our understanding of how fire characteristics have changed in the past, the results can inform mechanistic models to improve predictions of fire severity and intensity changes in the future.
Text
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Accepted/In Press date: 28 August 2025
e-pub ahead of print date: 1 September 2025
Published date: 1 September 2025
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© 2025 The Authors
Keywords:
Fire, Fire intensity, FTIR spectroscopy, Isotopes, Southeastern Australia
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Local EPrints ID: 506059
URI: http://eprints.soton.ac.uk/id/eprint/506059
ISSN: 0277-3791
PURE UUID: 545b6b7f-058e-4cda-821e-16e9d08df600
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Date deposited: 28 Oct 2025 17:37
Last modified: 29 Oct 2025 03:07
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Contributors
Author:
Rebecca Ryan
Author:
Shawn Lu
Author:
Damien Lemarchand
Author:
Zoë Thomas
Author:
Ivan Simkovic
Author:
Pavel Dlapa
Author:
Martin Worthy
Author:
Robert Wasson
Author:
Ross Bradstock
Author:
Katharine Haynes
Author:
Anthony Dosseto
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