Hydraulic traits of deciduous tree species: Do lessons learned from arid climates translate to eastern US temperate forests?

The coordination of plant leaf water potential (Ψ L ) regulation and xylem vulnerability to embolism is fundamental for understanding the tradeoffs between carbon uptake and risk of hydraulic damage. A legacy of observations in drylands suggests plants with vulnerable xylem more carefully regulate Ψ L than plants with resistant xylem. We synthesized over 1600 Ψ L observations, 122 xylem embolism curves, and xylem anatomical measurements of Quercus alba L., Liriodendron tulipifera L., and Acer saccharum Marsh. across ten contrasting forests to evaluate if the paradigm linking conservative Ψ L regulation to vulnerable xylem applies to temperate deciduous trees. Additionally, we explored generalizable patterns of hydraulic trait acclimation in relation to forest age and climate. Contrary to the dryland paradigm, we found that the tree species with the most vulnerable xylem (e.g., Q. alba ) regulated Ψ L less strictly (anisohydric behavior) than the species with xylem more resistant to embolism (e.g., A. saccharum and L. tulipifera ). This relationship was found across all sites, suggesting coordination among traits was largely unaffected spatio-temporal factors. Our findings indicate drought-response traits of temperate deciduous forest species are coordinated in fundamentally different ways than vegetation in arid climates.