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 (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 ΨL
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 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 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.