Shifts in rainfall patterns and increasing temperatures associated with climate change are predicted for most Neotropical dry forests in the following decades. Under these new scenarios, understanding the mechanisms driving plant drought responses is a priority due to their impact on ecosystem functioning. We measured leaf water potential at turgor loss point (πtlp) as a critical physiological determinant of a plant's tolerance to water stress. We also explored their relationship with 16 leaf and wood anatomy traits related to the leaf economics spectrum and hydraulic safety-efficiency trade-off. Drought tolerance, indexed by πtlp, ranged from -1.3 to -3.1 MPa among species, and was mainly linked to wood anatomy rather than leaf traits. Species with higher drought tolerance (lower πtlp) tended to have traits associated with high hydraulic safety, such as narrow vessels and pits, and low hydraulic efficiency measured as xylem potential hydraulic conductivity. Additionally, more drought-tolerant species showed high tissue investment, such as thick fibers and dense wood. The best model explained more than 50% of the variation in πtlp, and the most important traits were fiber wall thickness and water content. Our results highlight the high variability of woody species' drought responses and the importance of wood anatomy in explaining physiological responses to water deficit in tropical dry forests.
Drought tolerance, turgor loss point, wood anatomy traits, leaf traits