Résumé
Key messageOur study aims to define isotopic andanatomical responses to fires ofP. halepensis. Mainresults: decrease in tree growth and relative conduc-tivity and increase in water use efficiency.AbstractWe investigated the ecophysiological responsesof aPinus halepensisMill. stand surviving two wildfires insouthern France. Basal area, isotope composition andanatomical traits were analysed before and after fires, usingtree rings to assess the ecological responses of trees to heat-related damage. The years were determined based on thepresence of fire scars. Stable isotopes (d13C andd18O) weremeasured in tree rings before and after the ‘‘fire years’’.Anatomical observations allowed qualitative analysis ofthe scar region and quantification of tracheid size in treerings before and after the fire years. Relative and per-centage conductivity of earlywood and latewood far fromthe woundwood were estimated. Results showed a decreasein tree growth after the fire events accompanied by anincrease in13C-derived water use efficiency (WUEi) and adecrease in relative conductivity. The positive relationshipbetweend13C andd18O suggested that both isotopic vari-ations are mostly driven by changes in stomatal conduc-tance following fire events.P. halepensisproved to be astrong isohydric species, able to survive frequent fires withtemporary ecophysiological modifications and anatomicaladaptations. Our findings afford new insights into post-firesurvival strategies of this species in an environment wherefires are predicted to increase in frequency during thetwenty-first century