Evolution of fire regimes in East Java since the last glacial

Yanming Ruan, Mahyar Mohtadi, Sander Van Der Kaars, Lydie Dupont, Dierk Hebbeln, Ellen Hopmans, Stefan Schouten, Enno Schefuß

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Abstract

Fire causes dramatic energy and matter exchanges between the biosphere and atmosphere. The complex feedbacks between climate and vegetation complicates understanding how fire interacts with environmental changes (Archibald et al., 2018). Multiproxy paleo-records integrating these three critical parts of the Earth system are necessary to go beyond the short modern observational records and asses the role of fire in large-scale and long-term ecological changes.

Fire regime characteristics (such as frequency and intensity) are an important concept in describing fire (Bond and Keeley, 2005; Gill, 1975). Combining sedimentary charcoal and combustion-derived molecular markers (such as polycyclic aromatic hydrocarbons and monosaccharide anhydrates) is a promising way of more detailed fire regime reconstructions (Engling et al., 2014; Schüpbach et al., 2015). Their parallel detection allows not only reconstructing past fire frequency but also assessing fuel types and burning intensity.

Here we present polycyclic aromatic hydrocarbons (PAHs) together with charcoal data from a sediment core retrieved off East Java covering the past 22,000 years. Analyses of the monosaccharide anhydrates (levoglucosan, mannosan and galactosan) will be performed according to Schreuder et al. (2018). The results will be integrated with those presented here.

During the Last Glacial Maximum (22 to 18 kyrs before present), both high charcoal counts and total PAH concentrations indicate frequent fire occurrence. The dominance of low molecular weight PAHs implies relatively small fires, associated with lowland grass expansion and an extended dry season during that time. The last deglaciation (18 to 12 kyrs before present) is characterised by lower PAH concentrations but higher proportions of high molecular weight PAHs, implying a period of rare but more intense fires. Such a fire regime did not hamper the transition of the lowland vegetation from savannah into rainforest. The overall low charcoal counts and PAH concentrations during the Holocene indicate a low fire occurrence, probably due to the fire-resistance of closed-canopy vegetation.

The balance between frequency and intensity of fires observed spatially in modern ecology (Archibald et al., 2013; Murphy et al., 2013) thus likely is reflected in the temporal evolution of fire regimes in East Java.
Original languageEnglish
Title of host publication29th International Meeting on Organic Geochemistry, IMOG 2019
PublisherEuropean Association of Geoscientists and Engineers, EAGE
Pages1-2
Number of pages2
ISBN (Electronic)9789462823044
DOIs
Publication statusPublished - 2019
EventInternational Meeting on Organic Geochemistry (IMOG) 2019 - Gothenburg, Sweden
Duration: 1 Sept 20196 Sept 2019
Conference number: 29th

Publication series

Name29th International Meeting on Organic Geochemistry, IMOG 2019

Conference

ConferenceInternational Meeting on Organic Geochemistry (IMOG) 2019
Abbreviated titleIMOG 2019
Country/TerritorySweden
CityGothenburg
Period1/09/196/09/19

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