Fig. 1.

Hydraulic and photosynthetic traits vary substantially across the continental United States. Spatial variations in community-weighted (A) water potential at which 50% of stem xylem conductivity is lost (P50), (B) HSM, or the difference between the minimum stem water potential typically experienced and the P50, (C) xylem conductivity per total area of leaves distal to the measured xylem segment (K_L), and (D) maximum photosynthetic rate (A_max). White space indicates nonforested regions or regions where trait coverage was less that 80% by stand basal area.