XRCT images reveal climate control on wound recovery after intense flood in Mediterranean riparian trees

Climate change could impair riparian vegetation dynamics through more intense and frequent climatic extreme events such as flash flooding. However, it is still poorly known how climate warming can also impair vegetation recovery through control on cellular traits after such extreme events. Here, we analyze how Mediterranean riparian tree species (namely Alnus glutinosa, Fraxinus angustifolia, and Salix atrocinerea) recover after wounds caused by intense floods using 239 X-ray computed tomography (XRCT) images taken on 30 trees. The XRCT imagery allowed to characterize wounds-related macroscopic parameters in different sections along the stems in three dimensions. Then, we quantified the annual wound closure rates by dating dendrochronologically each wound and measuring the annual overgrowth on the wounded area. Finally, we used linear mixed models to investigate how wound closure rates are affected by climate conditions. Our results show that wound closure varies between species. A. glutinosa and F. angustifolia presented higher wound recovery rates than S. atrocinerea. However, the statistical analyses suggest that F. angustifolia and S. atrocinerea tend to recover much less(more) during drier(wetter) years than A. glutinosa. Our results suggest that A. glutinosa could be more stressed under climate change in the Mediterranean region, where the cooccurrence of drier conditions with extreme flood events may increase.