Data from: Predicting climatic limits along a rainfall gradient of dipterocarp species based on leaf turgor loss point

Drought tolerance is an integral determinant of drought survival in trees;
thus, an accurate and rapid assessment of drought tolerance can lead to
improved prediction of forest responses to droughts. The osmometer method
enables the rapid determination of the leaf water potential at turgor loss
(πtlp), a key parameter of drought tolerance, from the osmotic potential
at full turgor (πsat). However, despite its wide applications, there have
been few validations in ever-wet tropical rainforests. Here, we assessed
the efficacy of the osmometer method in dipterocarps, a dominant tree
group in SE Asia in ever-wet Malaysia, and examined the linkage between
πtlp and distribution along a rainfall gradient. The πtlp determined using
conventional method was strongly and linearly correlated with the πsat
determined using an osmometer. The coefficients of our model were
statistically identical to those previously represented, but with a
slightly larger intercept (0.21 MPa). Species with more negative πtlp were
distributed in drier habitats, with a relatively larger variation in πtlp
for species confined to ever-wet climates than for those occurring in
ever-wet and seasonally dry climates. Some leaf traits, individual leaf
area and dry matter content, were associated with πtlp, but these traits
alone could not predict species distribution. We demonstrated the
robustness of osmometer method in ever-wet tropical rainforest species and
that πtlp is associated with current distribution along large-scale
moisture availabilities.