Late Quaternary fire regimes of Australasia

S. D. Mooney (1) , S. P. Harrison (2) , P. J. Bartlein (3) , Anne-Laure Daniau (4) , J. Stevenson (5) , K. C. Brownlie (6) , S. Buckman (6) , M. Cupper (7) , J. Luly (8) , M. Black (1) , E. Colhoun (9) , E. D’costa (10) , J. Dodson , S. Haberle (5) , G. S. Hope (5) , P. Kershaw (11) , C. Kenyon (7) , M. Mckenzie (11) , N. Williams

1 UNSW - University of New South Wales [Sydney]
2 Macquarie University
3 University of Oregon [Eugene]
4 University of Bristol [Bristol]
5 ANU - Australian National University
6 University of Wollongong [Australia]
7 University of Melbourne
8 JCU - James Cook University
9 UoN - University of Newcastle [Callaghan, Australia]
10 University of Auckland [Auckland]
11 Monash University [Clayton]

We have compiled 223 sedimentary charcoal records from Australasia in order to examine the temporal and spatial variability of fire regimes during the Late Quaternary. While some of these records cover more than a full glacial cycle, here we focus on the last 70,000 years when the number of individual records in the compilation allows more robust conclusions. On orbital time scales, fire in Australasia predominantly reflects climate, with colder periods characterized by less and warmer intervals by more biomass burning. The composite record for the region also shows considerable millennial-scale variability during the last glacial interval (73.5e14.7 ka). Within the limits of the dating uncertainties of individual records, the variability shown by the composite charcoal record is more similar to the form, number and timing of DansgaardeOeschger cycles as observed in Greenland ice cores than to the variability expressed in the Antarctic ice-core record. The composite charcoal record suggests increased biomass burning in the Australasian region during Greenland Interstadials and reduced burning during Greenland Stadials. Millennial-scale variability is characteristic of the composite record of the subtropical high pressure belt during the past 21 ka, but the tropics show a somewhat simpler pattern of variability with major peaks in biomass burning around 15 ka and 8 ka. There is no distinct change in fire regime corresponding to the arrival of humans in Australia at 50 AE 10 ka and no correlation between archaeological evidence of increased human activity during the past 40 ka and the history of biomass burning. However, changes in biomass burning in the last 200 years may have been exacerbated or influenced by humans.

Mots clés: charcoal records; fire; biomass burning; vegetation-fire interactions; human impact on fire; Last Glacial Maximum; Holocene; Dansgaard-Oeschger variability; ENSO variability

Domaines: Sciences de l'environnement; Planète et Univers [physics]

S. D. Mooney, S. P. Harrison, P. J. Bartlein, Anne-Laure Daniau, J. Stevenson, et al.. Late Quaternary fire regimes of Australasia. Quaternary Science Reviews, 2011, 30 (1-2), pp.28-46. ⟨10.1016/j.quascirev.2010.10.010⟩. ⟨hal-03210816⟩