Reconstructing Holocene Vegetation, Fire, and Climate Interactions in the Mediterranean Using Speleothem Archives

Understanding the long-term interactions among vegetation, fire, and climate is critical for interpreting ecosystem responses to climatic perturbations. Project Prometheus investigates Holocene paleofire dynamics, vegetation shifts, and climate variability in the Mediterranean, using speleothem records from caves in Italy (Alps, Apennines, Sardinia) and the Balkans. By integrating multiple proxies, including polycyclic aromatic hydrocarbons (PAHs) as fire markers and n-alkanes as a proxy for vegetation composition and terrigenous input, this project aims to provide insights into the environmental drivers of fire activity from millennial to sub-centennial timescales, thus creating a high resolution fire history for the Mediterranean region. Speleothems offer a novel paleoenvironmental archive, and we apply an advanced hydrocarbon extraction protocol adapted from a study on Australian stalagmites1. This method, which includes slow acid dissolution in a clean-room setting to minimize contamination and maximize compound yields, has significantly improved the detection limits and expanded the range of PAHs identified2. Uranium-thorium (U-Th) dating ensures a precise chronological framework, enabling robust correlation between fire, vegetation, and climate proxies. Here we present results from the initial phase of the project, analyizing a dozen archives from Italy, Greece, and Northern Macedonia, at low resolution (millennial- and sub-millennial-scale). Preliminary results, will provide a first indication of technique effectiveness, archive quality, and regional historical variations (if any) in paleofire regimes. Comparative studies with paleofire data from lake sediments in Italy, where shifts in fire regimes have been previously documented, as well as with modern fire data derived from registries and satellite observations, will help contextualizing our findings within broader regional fire histories. This research advances our understanding of vegetation-wildfire-climate interactions in the Mediterranean by contributing high-resolution, multi-proxy reconstructions from an understudied archive. By linking past fire and vegetation responses to climatic variability, it provides critical context for assessing future ecosystem resilience and informing land management policies under changing climate conditions.