Spatial heterogeneity of wildfires in Southern China during the Last Glacial Maximum

Liu, Binxu

GLOBAL AND PLANETARY CHANGE

2026

262

Liu, J; Su, T

Wildfire exerts significant influences on ecosystem succession, carbon cycles, and climate evolution; therefore, understanding the history of wildfire and its forcing factors in the geological past is of great importance. However, most paleofire records are confined to the Last Deglaciation (after 19 cal kyr BP), with few from earlier periods, hindering understanding of long-term spatiotemporal patterns of regional wildfire and climate. In this study, we reconstruct the relationship between wildfire and climate in southwestern China from similar to 33 to 14 cal kyr BP by analyzing polycyclic aromatic hydrocarbons (PAHs), organic carbon isotopes (delta C-13(org)), and geochemical elements from the Xujiaba (XJB) peatland on the Ailao Mountains in Yunnan Province. Our findings indicate that, on orbital timescales, wildfire activity increased from similar to 33 to 18 cal kyr BP and then decreased after that. Wildfire frequency was higher during Marine Isotope Stage (MIS) 2 than MIS 3. Cross-wavelet transform analysis reveals that wildfire activity was primarily driven by fluctuations in precipitation. Furthermore, by comparing paleofire records from central-eastern and southeastern China, we found an asynchronous pattern of wildfire activity in southern China during the Last Glacial Maximum (LGM). This pattern may be linked to regional hydroclimate heterogeneity between southwestern and central-eastern/southeastern China resulting from a weakened Asian monsoon and El Ni & ntilde;o-Southern Oscillation (ENSO) variability. This study provides important insights for understanding large-scale wildfire patterns, as well as forcing factors, during the LGM.