Additional file 1. Photographic overview of the experimental setup of the Fraxinus excelsior L. tree in the custom-built holder with carbon fiber tube designed to ensure stable and centered positioning of the tree during µCT scanning (A). The tree is equipped with two broadband point-contact AE sensors in a pvc spring-containing holder to continuously register AEs from the progressively dehydrating xylem (AE1, AE2), and a point dendrometer to continuously register xylem shrinkage. This potentiometer-type of dendrometer was selected, as its working principle does not generate a magnetic field, which would otherwise produce acoustic interference.