Figure 1.

Vulnerability curves (VCs) reporting the relationship between stem-specific hydraulic conductivity (K_s) and xylem water potential (Ψ_xyl), as measured for healthy (H, closed circles, solid line) and desiccated (D, open circles, dashed line) P. nigra trees. The sigmoidal regressions are also reported. The Ψ_xyl inducing 20 (P₂₀) and 50 (P₅₀) % loss of K_s were −1.67 and −3.24 MPa, and −1.42 and −3.63 MPa for H and D group, respectively (fit-PLC, Duursma and Choat, 2016). The insets show the VC of H trees based on K_s data that were within the observable range for both populations (0.03–0.68 kg s⁻¹ MPa⁻¹ m⁻¹).