3.1 Differences in xylem hydraulic and structural traits between branches and roots
P 50 root and P 50 branchwere positively correlated (r 2 = 0.72, P< 0.001), with roots being more vulnerable to cavitation than branches across a 96% of the studied species (Figure 1a). Compared with roots, 94% of the studied species showed higherK S branch values (Figure 1b). In addition, 79% of the species had highert 2/b 2 values in branches than in roots (Figure 1c), and about 98% of the species had roots with wider hydraulically weighted vessel or tracheid diameter than branches (Figure 1d). Additionally, all these root hydraulic and xylem anatomical traits were positively associated with the ones of the branch (Fig 1).