Data from: Wood anatomical and hydraulic traits of Tamarix species across a large Eurasian gradient show a stronger climatic than phylogenetic signal

Aim: Tamarisk (Tamarix) is the predominant but taxonomically complex genus
of the Tamaricaceae. The morphologically similar shrub or tree species
grow in arid, salt-influenced habitats of Eurasia and Africa. We sampled
woody shoots of seven species at the eastern margin (NW China;
T. ramosissima) and the centre (Uzbekistan; T. hispida)
of the Indo-Turanian region as well as at the eastern (Israel;
T. aphylla, T. negevensis, T. nilotica) and
western margin (southern Spain; T. boveana, T. gallica)
of the Mediterranean region, the two diversity centres of the genus. To
explore the drivers of intrageneric trait variability, we investigated
whether differences in the anatomical-hydraulic wood traits among the
species are related to climate or phylogeny. Location: Eurasia. Taxon:
Tamarix L. (Tamaricaceae). Methods: We determined features of wood anatomy
and calculated the hydraulic conductivity (kt) and the water potential at
50% loss of hydraulic conductance (P50). We related these traits to
climate variables and to the phylogenetic distances among the species.
Results: Tamarix nilotica, T. negevensis and
T. ramosissima exhibited large conduit areas, large hydraulic
diameters and high kt, whereas the Spanish species T. gallica and
T. boveana displayed high wood densities and a small fraction of
large conduits. The phylogenetically distant species T. aphylla
and T. hispida took intermediate positions. Tamarix ramosissima,
which grows in regions with cold winters and hot-dry summers, exhibited
the most negative P50 values, indicative of a low susceptibility to a
failure of the water-conducting system. Trait differences among the
species were unrelated to the species' phylogenetic relatedness but
correlated with climate variables. Main Conclusions: Despite strong
similarity in morphology and habitat preferences, Tamarix species
displayed significant differences in their anatomical-hydraulic traits.
These differences were related to climate conditions rather than phylogeny
and are indicative of specific local adaptations to environmental
conditions.