Effect of climate on ring-width and vessel variables of Vachellia macracantha from dry forest in Southern Ecuador

How do climatic conditions, particularly rainfall, influence the radial growth and vascular traits of Vachellia macracantha in tropical dry forests? This study aimed to measure the tree-ring width (TRW) and vascular variables (AVLA, TVLA, VDLA) of V. macracantha in the Tumbesian dry forest of southern Ecuador, construct chronologies for these variables, and analyze their relationship with precipitation. Using standard dendrochronological methods, we measured TRW and vascular traits, subsequently developing chronologies for both TRW and the vessel variables. These chronologies were correlated with precipitation data to assess climate-growth relationships. Results showed a positive correlation between precipitation and both TRW and AVLA, indicating that higher rainfall promotes radial growth and larger vessel lumen areas. In contrast, precipitation was negatively correlated with TVLA and VDLA, suggesting a decrease in vessel density and total lumen area under wetter conditions. These findings underscore the adaptability of V. macracantha to fluctuating water availability, demonstrating how it balances hydraulic efficiency and safety. By integrating dendrochronology and wood anatomy, this study provides critical insights into the growth dynamics of tropical dry forests and offers a robust foundation for conservation strategies in the face of changing climate conditions.