Sample preparation
All samples were collected before 9:00 in the morning. After cutting samples from a tree in air, large branches were immediately put in a water-filled bucket and a ca. 20 cm stem segment was cut from the stem base under water to avoid air entry as much as possible. The length of the remaining branch samples was between 80 and 160 cm, which was much longer than the maximum vessel length (MVLstem). Samples were covered up with a dark plastic bag, transferred to the lab within 10 min, and then rehydrated for more than two hours.