oa Wildfire, Climate and Landscape Evolution in the Western Sahel Across the Eocene-Oligocene Transition

Wildfire is an integral part of terrestrial ecosystems with their occurrence, intensity and frequency interlinked with complex feedback mechanisms involving climate, carbon cycling, landscape structure and vegetation. The Eocene-Oligocene Transition (EOT) is characterized by global cooling, decreasing atmospheric pCO2 and major global ecological restructuring. Terrestrial ecosystems during the EOT exhibited regionally variable responses, yet African biome changes remain under-studied ( Pound and Salzmann, 2017 ). Here we present a record of 3- to 7-ringed polycyclic aromatic hydrocarbons (PAHs) and long-chained n-alkane biomarkers from ODP Site 959 in the Gulf of Guinea to investigate Western Sahel wildfire, vegetation and precipitation dynamics across the EOT boundary condition shift. Long-chained n-alkane data suggest relatively minor changes in vegetation structure across the transition, while PAHs indicate a decrease in wildfire activity and a shift in burnt vegetation. These findings suggest that vegetation was not the primary driver of wildfire dynamics in the Western Sahel region, with precipitation patterns, atmospheric pCO2 or surfaces temperatures possibly playing a more dominant role in wildfire changes. These findings enhance our understanding of wildfire dynamics within the constraints of feedback mechanisms between climate, vegetation and carbon cycling in this region.