Applications of charcoal morphometry and morphology during the Cretaceous Period

Abstract

Wildfire regimes are intensifying globally due to anthropogenic climate change, necessitating improved methods for reconstructing past fire activity to inform future mitigation strategies. The Cretaceous period, particularly the Campanian stage, serves as a valuable analog for future greenhouse climates due to its elevated atmospheric CO₂ levels and absence of polar ice caps. This thesis refines the use of sedimentary charcoal as a proxy for paleofire and paleoecological reconstructions by conducting novel experimental and in situ analyses. We present novel data morphometrics based on aspect ratio (L:W), circularity, rectangularity, and feret diameter, revealing that charcoal morphology varies significantly at the tissue and component levels. Our findings indicate that Cretaceous wildfires were predominantly low-intensity surface fires fueled by ferns and small angiosperms, with taphonomic processes influencing charcoal preservation. These insights improve fire history reconstructions and underscore the importance of modern fuel reduction strategies, such as controlled burns, to mitigate future wildfire risks in warming climates.