Climate change and fragmentation are major threats to tropical dry forests in Colombia. As a consequence, improving our understanding of functional traits variation related to drought tolerance across environmental gradients becomes critical for predicting tree species responses to future climate change. We explored intraespecific variability of wood density, two leaf and five xylem anatomy traits across precipitation gradients in six tree species that occur in Colombian tropical dry forests. We sampled between four to ten populations per species, and at least five individuals per population. We determined wood density (WD), vessels diameter and density (VDi, VD), fiber (Fl) and vessels lenght (Vl) and pits (P) from wood cores, and from leaves we determine specific leaf area (SLA) and leaf dry matter content (LDMC). Climatic data were obtain from WorldClim.
Leaf traits were more labil than anatomic xylem traits. Drier populations showed higher LDMC and LMA than mesic populations in all species. In contrast, P, Fl and Vl did not vary across populations. Few species showed variations in VDi, with lower values in drier populations. The ability of tree species to modify leaf traits in response to differences in precipitation could facilitate its persistence in contrasting environments. However, xylem anatomy showed limited trait variation despite differences in precipitation, which could induce high levels of embolism and drought stress in drier places and seasons. Reductions in rainfall and increment in interanual variability predicted for the forests could expose those populations to greater drought stress and mortality.