2. Abstract
The coordination of plant leaf water potential (ΨL)
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 ΨL than plants
with resistant xylem. We synthesized over 1600 ΨLobservations, 122 xylem embolism curves, and xylem anatomical
measurements of Quercus alba L., Liriodendrontulipifera L., and Acer saccharum Marsh. across ten
contrasting forests to evaluate if the paradigm linking conservative
ΨL 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
ΨL less strictly (anisohydric behavior) than the species
with xylem more resistant to embolism (e.g., A. saccharum andL. 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.