Data from: Addressing controversies in the xylem embolism resistance – vessel diameter relationship

Although xylem embolism is a key process during drought-induced tree
mortality, its relationship to wood anatomy remains debated. While the
functional link between bordered pits and embolism resistance is known,
there is no direct, mechanistic explanation for the traditional assumption
that wider vessels are more vulnerable than narrow ones. We used data from
20 temperate broad-leaved tree species to study the inter- and
intraspecific relationship of water potential at 50% loss of conductivity
(P50) with hydraulically-weighted vessel diameter (Dh) and tested its link
to pit membrane thickness (TPM) and specific conductivity (Ks) on species
level. Embolism-resistant species had thick pit membranes and narrow
vessels. While Dh was weakly associated with TPM, the P50 – Dh
relationship remained highly significant after accounting for TPM. The
interspecific pattern between P50 and Dh was mirrored by a link between
P50 and Ks, but there was no evidence for an intraspecific relationship.
Our results provide robust evidence for an interspecific P50 – Dh
relationship across our species. As a potential cause for the
inconsistencies in published P50 – Dh relationships, our analysis suggests
differences in the range of traits values covered, and the level of data
aggregation (species, tree, or sample level) studied.