Fire and fuel in Holocene northern Australian tropical savannas

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dc.contributor.authorRehn, Een_AU
dc.contributor.authorBird, MIen_AU
dc.contributor.authorRowe, Cen_AU
dc.contributor.authorUlm, Sen_AU
dc.contributor.authorWoodward, Cen_AU
dc.contributor.authorJacobsen, GEen_AU
dc.date.accessioned2023-08-20T21:26:27Zen_AU
dc.date.available2023-08-20T21:26:27Zen_AU
dc.date.issued2019-07-26en_AU
dc.date.statistics2023-04-13en_AU
dc.description.abstractFire has a long history of interaction with Australian ecosystems but poses a growing risk as future climate change is predicted to lengthen fire seasons and increase extreme fire weather. Tropical savannas cover almost one quarter (1.9 million km2) of the Australian land mass, and fire occurs here almost annually. A greater understanding of past fire regimes, and their environmental context, is essential for management and planning in an increasingly fire-prone landscape. Despite the central importance of fire in savanna ecosystems, the region remains understudied in Australian palaeofire research. In light of this knowledge gap, this study combines established and emerging optical and chemical methods for charcoal analysis in the context of northern Australian tropical savannas. This study presents three new Holocene palaeofire records from tropical savanna wetland sites in far northern Australia, each with diverse land-use histories. Three methods were applied to achieve a more comprehensive understanding of fire and fuels over time in tropical savannas. Charcoal abundance is presented for four size classes covering a local signal (>250 µm and 250-125 µm) and surrounding regional signal (125-63 µm and <63 µm). Particle morphology and aspect ratio are proposed indicators of fuel type (e.g. grass, leaf, wood). However, this technique derives primarily from temperate environments, notably from experimental burns and sites in the Northern Hemisphere. Our study tests methods developed in temperate, Northern Hemisphere settings on charcoal from the Australian tropical savanna. Fuel type data are discussed using a morphotype classification system, and a length-width ratio of ≥3.6 is used to identify macroscopic grass particles. We demonstrate the application of chemical quantification of pyrogenic carbon (PyC) as well as isotopic identification of fuel type. PyC abundance determined using hydrogen pyrolysis and δ13C composition (contribution of C3 versus C4 plants) are presented for the three sites and combined with the data generated using optical methods. All records are supported by 210Pb and 14C chronologies and XRF core scanner data on elemental composition. Preliminary results show negligible variations in fuel composition through time at each site, with broad correspondence between fuel type determined by morphology and isotope composition. Variations are apparent between different charcoal size classes (macroscopic and microscopic) in both abundance and fuel composition at all sites, reflecting differences in local and regional fire signals and highlighting the importance of size differentiation during analysis. This study is a step towards filling the palaeofire knowledge gap represented by northern Australia and is an important assessment of the application of existing palaeofire techniques to this unique context. © The Authors.en_AU
dc.identifier.citationRehn, E., Bird, M., Rowe, C., Ulm, S., Woodward, C., & Jacobsen, G. (2019). Fire and fuel in Holocene northern Australian tropical savannas. Paper presented to the 20th INQUA Congress 25th - 31st July 2019, Dublin, Ireland. Retrieved from: https://virtual.oxfordabstracts.com/#/event/public/574/submission/112en_AU
dc.identifier.conferenceenddate2019-07-31en_AU
dc.identifier.conferencename20th INQUA Congressen_AU
dc.identifier.conferencenameDublin, Irelanden_AU
dc.identifier.conferencestartdate2019-07-25en_AU
dc.identifier.urihttps://virtual.oxfordabstracts.com/#/event/public/574/submission/112en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15095en_AU
dc.language.isoenen_AU
dc.publisherInternational Union for Quaternary Research (INQUA)en_AU
dc.relation.urihttps://virtual.oxfordabstracts.com/#/event/public/574/submission/112en_AU
dc.subjectFiresen_AU
dc.subjectEcosystemsen_AU
dc.subjectClimatic changeen_AU
dc.subjectAustraliaen_AU
dc.subjectCharcoalen_AU
dc.subjectWetlandsen_AU
dc.subjectX-ray fluorescence analysisen_AU
dc.subjectQuaternary perioden_AU
dc.titleFire and fuel in Holocene northern Australian tropical savannasen_AU
dc.typeConference Abstracten_AU
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