Interaction of Fire, Vegetation, and Climate in Tropical Ecosystems: A Multiproxy Study Over the Past 22,000 Years

Abstract

Fire causes dramatic energy and matter exchanges between biosphere and atmosphere on a regional to global scale. Predicting fires, however, is hindered by the complex interplay of fire, climate, and vegetation. Paleo-fire records provide critical information beyond instrumental records that cover only the past few decades and may be used to assess the role of fire in large-scale and long-term environmental changes. Here we present a 22,000-year multiproxy record of fire regime from a sediment core retrieved offshore South Java, Indonesia. We use microcharcoal in combination with two molecular markers of burning, levoglucosan and polycyclic aromatic hydrocarbons, to reconstruct fire occurrence as well as fire intensity in the past. We show that fire occurrence and intensity were high during the Last Glacial Maximum (LGM; around 21,000 years ago) and low during the Heinrich Stadial 1 and the early Holocene. Both fire regime and vegetation in tropical regions with high annual rainfall were primarily controlled by rainfall seasonality. However, fire additionally stabilized the savannah (rainforest)-dominated ecosystem during the LGM (early Holocene) but caused transitions between the two vegetation types during the deglaciation and the late Holocene. Changes in fire regime are often not resolved in paleo-records (Archibald et al., 2018; Han et al., 2016). Charcoal, commonly used as a proxy to indicate past fire activity, is a carbonaceous material produced by incomplete combustion of biomass with temperatures between 280°C and 500°C (Whitlock & Larsen, 2002). Microcharcoal abundance in marine sediments reflects general fire occurrence on a

The response of wildfire regimes to Last Glacial Maximum carbon dioxide and climate

“…BA Our model results reproduce the global reduction of biomass burning at the LGM observed from ice cores and sedimentary charcoal records (Daniau et al, 2012;Harrison et al, 2022;Power et al, 2008;Rubino et al, 2016). Some studies have indicated the occurrence of high-intensity wildfires on the Palaeo-Agulhas Plain of South Africa, tropical regions, northern Australia, and central China at the LGM (Kraaij et al, 2020;Power et al, 2008;Rowe et al, 2021;Ruan et al, 2020;M. Song et al, 2023).…”

Indigenous impacts on north Australian savanna fire regimes over the Holocene

“…By contrast, charcoal particles are produced at all temperatures and thus reflects general fire frequency. This proxy is similar to PAH ratios used to determine changes in Indonesian fire regimes over the past 22,000 years 45 . For this study, samples were decarbonated by immersion in 2 M HCl for 3 h and measured for the total organic carbon abundance (TOC).…”

Negligible Quantities of Particulate Low‐Temperature Pyrogenic Carbon Reach the Atlantic Ocean via the Amazon River

“…Comparative studies on soils and aerosols have shown that the most commonly used extraction protocol for levoglucosan using MeOH or DCM:MeOH mixtures yielded comparable result (Cordell et al., 2014 ; Hopmans et al., 2013 ). While these comparisons were conducted on modern sample material, a study from a Pleistocene marine sediment core showed that MeOH extraction was on average five times more efficient than DCM:MeOH 9:1 (Ruan et al., 2020 ). While all modern marine and riverine sediment data sets reported here were produced using DCM: MeOH mixtures, the discussed Holocene lacustrine sediment records were produced using MeOH as extraction solvent (Elias et al., 2001 ; Hunsinger et al., 2008 ; Myers‐Pigg et al., 2017 ; Schreuder et al., 2018 ; Schupbach et al., 2015 ).…”