Leaf habit affects the distribution of drought sensitivity but not water transport efficiency in the tropics

<b>Abstract</b><br/><p>Considering the global intensification of aridity in tropical biomes due to climate change, we need to understand what shapes the distribution of drought sensitivity in tropical plants. We conducted a pantropical data synthesis representing 1117 species to test whether xylem-specific hydraulic conductivity (K<sub>S</sub>), water potential at leaf turgor loss (Ψ<sub>TLP</sub>), and water potential at 50% loss of K<sub>S</sub> (ΨP50) varied along climate gradients. The Ψ<sub>TLP</sub> and ΨP<sub>50</sub> increased with climatic moisture only for evergreen species, but K<sub>S</sub> did not. Species with high Ψ<sub>TLP</sub> and Ψ<sub>P50</sub> values were associated with both dry and wet environments. However, drought-deciduous species showed high Ψ<sub>TLP</sub> and ΨP<sub>50</sub> values regardless of water availability whereas evergreen species only in wet environments. All three traits showed a weak phylogenetic signal and a short half-life. These results suggest that environmental controls on trait variance, which in turn is modulated by leaf habit along climatic moisture gradients in the tropics.</p>