Changes in the fire resilience of Mediterranean trees in response to climate variability over the past 300 Years

Bulle I. Alberto, Justin Badeau, Frédéric Guibal, Aurèle Baretje, Jean-Christophe Domec, Christopher Carcaillet

With global warming, understanding the tree resilience to fire is still a scalding topic in ecology. Tree resilience would depend on fire intervals, and on interactions with atmospheric conditions, including temperature, precipitation, drought, and CO₂. These interactions would be exacerbated in Mediterranean ecosystems. We test this hypothesis by analysing variations in tree-ring widths following fires, using growth outside fire periods as reference. The study focused on black pine in Corsica as a model species to investigate long-term ecological responses to fire, based on fires spanning the past 300 years. Tree resistance and resilience to fire have progressively declined over the past three centuries, regardless of fire intervals and CO₂. Since the mid-19th century, recovery times have lengthened while resistance has weakened, correlating with precipitation and drought intensity. These results indicate that the combined effects of drought intensity and fires endanger tree survival by compounding their impacts on post-fire recovery.