Modelled dispersal patterns for wood and grass charcoal are different: implications for paleofire reconstruction

Vachula, Richard S., and Rehn, Emma (2022) Modelled dispersal patterns for wood and grass charcoal are different: implications for paleofire reconstruction. The Holocene. (In Press)

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Abstract

Sedimentary charcoal records provide useful perspectives on the long-term controls and behavior of fire in the Earth system. However, a comprehensive understanding of the nuances, biases, and limitations of charcoal as a fire proxy is necessary for reliable paleofire interpretations. Here, we use a charcoal dispersal model to answer the following questions: (1) How does the dispersal of wood and grass charcoal particles differ? (2) Do traditional conceptual models of charcoal dispersal reliably characterize grass charcoal dispersal? We find that small differences in shape (L:W) and density of grass and wood charcoal can cause substantial differences in particle dispersal and source area. Whereas the modelled dispersal of wood charcoal shows a localized deposition signal which decays with distance, grass charcoal shows more diffuse deposition lacking a localized center (for both >125 µm and >60 µm). Although paleofire research has typically not distinguished between fuel types, we show that the dispersal of charcoal derived from different fuels is unlikely to be uniform. Because differences in localization, production, and preservation could bias aggregate charcoal accumulation, caution should be taken when interpreting wood and grass-derived charcoal particles preserved in the same record. Additionally, we propose an alternative, dual background conceptual model of grass charcoal dispersal, as the traditional, two-component (peak and background) conceptual model does not accurately characterize the modelled dispersal of grass charcoal. Lastly, this mismatch of conceptualizations of dispersal mechanics implies that grass charcoal may not fit the criteria necessary for peak analysis techniques.

Item ID: 76791
Item Type: Article (Research - C1)
ISSN: 1477-0911
Keywords: charcoal source area; fire history; taphonomy; paleoecology
Copyright Information: The accepted version may be made open access in a non-commercial institutional repository without embargo.
Date Deposited: 14 Nov 2022 23:49
FoR Codes: 37 EARTH SCIENCES > 3709 Physical geography and environmental geoscience > 370905 Quaternary environments @ 40%
37 EARTH SCIENCES > 3704 Geoinformatics > 370401 Computational modelling and simulation in earth sciences @ 60%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280111 Expanding knowledge in the environmental sciences @ 50%
28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 50%
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